1
|
Cáceres E, Divani AA, Rubinos CA, Olivella-Gómez J, Viñan Garcés AE, González A, Alvarado Arias A, Bhatia K, Samadani U, Reyes LF. PaCO 2 Association with Outcomes of Patients with Traumatic Brain Injury at High Altitude: A Prospective Single-Center Cohort Study. Neurocrit Care 2024:10.1007/s12028-024-01982-8. [PMID: 38740704 DOI: 10.1007/s12028-024-01982-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 03/12/2024] [Indexed: 05/16/2024]
Abstract
BACKGROUND Partial pressure of carbon dioxide (PaCO2) is generally known to influence outcome in patients with traumatic brain injury (TBI) at normal altitudes. Less is known about specific relationships of PaCO2 levels and clinical outcomes at high altitudes. METHODS This is a prospective single-center cohort of consecutive patients with TBI admitted to a trauma center located at 2600 m above sea level. An unfavorable outcome was defined as a Glasgow Outcome Scale-Extended (GOSE) score < 4 at the 6-month follow-up. RESULTS We had a total of 81 patients with complete data, 80% (65/81) were men, and the median (interquartile range) age was 36 (25-50) years. Median Glasgow Coma Scale (GCS) score on admission was 9 (6-14); 49% (40/81) of patients had severe TBI (GCS 3-8), 32% (26/81) had moderate TBI (GCS 12-9), and 18% (15/81) had mild TBI (GCS 13-15). The median (interquartile range) Abbreviated Injury Score of the head (AISh) was 3 (2-4). The frequency of an unfavorable outcome (GOSE < 4) was 30% (25/81), the median GOSE was 4 (2-5), and the median 6-month mortality rate was 24% (20/81). Comparison between patients with favorable and unfavorable outcomes revealed that those with unfavorable outcome were older, (median age 49 [30-72] vs. 29 [22-41] years, P < 0.01), had lower admission GCS scores (6 [4-8] vs. 13 [8-15], P < 0.01), had higher AISh scores (4 [4-4] vs. 3 [2-4], P < 0.01), had higher Acute Physiology and Chronic Health disease Classification System II scores (17 [15-23] vs. 10 [6-14], P < 0.01), had higher Charlson scores (0 [0-2] vs. 0 [0-0], P < 0.01), and had higher PaCO2 levels (mean 35 ± 8 vs. 32 ± 6 mm Hg, P < 0.01). In a multivariate analysis, age (odds ratio [OR] 1.14, 95% confidence interval [CI] 1.1-1.30, P < 0.01), AISh (OR 4.7, 95% CI 1.55-21.0, P < 0.05), and PaCO2 levels (OR 1.23, 95% CI 1.10-1.53, P < 0.05) were significantly associated with the unfavorable outcomes. When applying the same analysis to the subgroup on mechanical ventilation, AISh (OR 5.4, 95% CI 1.61-28.5, P = 0.017) and PaCO2 levels (OR 1.36, 95% CI 1.13-1.78, P = 0.015) remained significantly associated with the unfavorable outcome. CONCLUSIONS Higher PaCO2 levels are associated with an unfavorable outcome in ventilated patients with TBI. These results underscore the importance of PaCO2 levels in patients with TBI and whether it should be adjusted for populations living at higher altitudes.
Collapse
Affiliation(s)
- Eder Cáceres
- Unisabana Center for Translational Science, School of Medicine, Universidad de La Sabana, Chía, Colombia.
- Department of Bioscience, School of Engineering, Universidad de La Sabana, Chía, Colombia.
- Department of Critical Care, Clínica Universidad de La Sabana, Chía, Colombia.
| | - Afshin A Divani
- Department of Neurology, The University of New Mexico, Albuquerque, NM, USA
| | - Clio A Rubinos
- Department of Neurology, University of North Carolina, Chapel Hill, NC, USA
| | - Juan Olivella-Gómez
- Department of Critical Care, Clínica Universidad de La Sabana, Chía, Colombia
| | | | - Angélica González
- Department of Critical Care, Clínica Universidad de La Sabana, Chía, Colombia
| | | | - Kunal Bhatia
- Department of Neurology, University of Mississippi Medical Center, Jackson, MS, USA
| | - Uzma Samadani
- Department of Neurosurgery, Minneapolis VA Health Care System, Minneapolis, MN, USA
| | - Luis F Reyes
- Unisabana Center for Translational Science, School of Medicine, Universidad de La Sabana, Chía, Colombia
- Department of Critical Care, Clínica Universidad de La Sabana, Chía, Colombia
- Pandemic Sciences Institute, University of Oxford, Oxford, UK
| |
Collapse
|
2
|
Caceres E, Divani AA, Rubinos CA, Olivella-Gómez J, Viñán-Garcés AE, González A, Alvarado-Arias A, Bathia K, Samadani U, Reyes LF. PaCO2 Association with Traumatic Brain Injury Patients Outcomes at High Altitude: A Prospective Single-Center Cohort Study. RESEARCH SQUARE 2024:rs.3.rs-3876988. [PMID: 38343855 PMCID: PMC10854293 DOI: 10.21203/rs.3.rs-3876988/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
Background partial pressure of carbon dioxide (PaCO2) is generally known to influence outcome in patients with traumatic brain injury (TBI) at normal altitudes. Less is known about specific relationships of PaCO2 levels and clinical outcomes at high altitudes. Methods This is a prospective single-center cohort of consecutive TBI patients admitted to a trauma center located at 2600 meter above sea level. An unfavorable outcome was defined as the Glasgow Outcome Scale-Extended (GOSE) < 4 at 6-month follow-up. Results 81 patients with complete data, 80% (65/81) were men, and median (IQR) age was 36 (25-50) years). Median Glasgow Coma Scale (GCS) on admission was 9 (6-14), 49% (40/81) were severe (GCS: 3-8), 32% (26/81) moderate (GCS 12 - 9), and 18% (15/81) mild (GCS 13-15) TBI. The median (IQR) Abbreviated Injury Score of the Head (AISh) was 3 (2-4). Frequency of an unfavorable outcome (GOSE < 4) was 30% (25/81), median GOSE was 4 (2-5), and 6-month mortality was 24% (20/81). Comparison between patients with favorable and unfavorable outcomes revealed that those with unfavorable outcome were older, median [49 (30-72) vs. 29 (22-41), P < 0.01], had lower admission GCS [6 (4-8) vs. 13 (8-15), P < 0.01], higher AIS head [4 (4-4) vs. 3(2-4), p < 0.01], higher APACHE II score [17(15-23) vs 10 (6-14), < 0.01), higher Charlson score [0(0-2) vs. 0 (0-0), P < 0.01] and higher PaCO2 (mmHg), mean ± SD, 39 ± 9 vs. 32 ± 6, P < 0.01. In a multivariate analysis, age (OR 1.14 95% CI 1.1-1.30, P < 0.01), AISh (OR 4.7 95% CI 1.55-21.0, P < 0.05), and PaCO2 (OR 1.23 95% CI: 1.10-1.53, P < 0.05) were significantly associated with the unfavorable outcomes. When applying the same analysis to the subgroup on mechanical ventilation, AISh (OR 5.4 95% CI: 1.61-28.5, P = 0.017) and PaCO2 (OR 1.36 95% CI: 1.13-1.78, P = 0.015) remained significantly associated with the unfavorable outcome. Conclusion Higher PaCO2 levels are associated with an unfavorable outcome in ventilated TBI patients. These results underscore the importance of PaCO2 level in TBI patients and whether it should be adjusted for populations living at higher altitudes.
Collapse
Affiliation(s)
| | - Afshin A Divani
- University of New Mexico - Albuquerque: The University of New Mexico
| | - Clio A Rubinos
- University of North Carolina at Chapel Hill Health Sciences Library: The University of North Carolina at Chapel Hill
| | | | | | | | - Alexis Alvarado-Arias
- University of Mississippi University Hospital: The University of Mississippi Medical Center
| | - Kunal Bathia
- University of Mississippi University Hospital: The University of Mississippi Medical Center
| | | | | |
Collapse
|
3
|
Veraar CM, Rinösl H, Kühn K, Skhirtladze-Dworschak K, Felli A, Mouhieddine M, Menger J, Pataraia E, Ankersmit HJ, Dworschak M. Non-pulsatile blood flow is associated with enhanced cerebrovascular carbon dioxide reactivity and an attenuated relationship between cerebral blood flow and regional brain oxygenation. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2019; 23:426. [PMID: 31888721 PMCID: PMC6937980 DOI: 10.1186/s13054-019-2671-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 11/13/2019] [Indexed: 12/16/2022]
Abstract
BACKGROUND Systemic blood flow in patients on extracorporeal assist devices is frequently not or only minimally pulsatile. Loss of pulsatile brain perfusion, however, has been implicated in neurological complications. Furthermore, the adverse effects of absent pulsatility on the cerebral microcirculation are modulated similarly as CO2 vasoreactivity in resistance vessels. During support with an extracorporeal assist device swings in arterial carbon dioxide partial pressures (PaCO2) that determine cerebral oxygen delivery are not uncommon-especially when CO2 is eliminated by the respirator as well as via the gas exchanger of an extracorporeal membrane oxygenation machine. We, therefore, investigated whether non-pulsatile flow affects cerebrovascular CO2 reactivity (CVR) and regional brain oxygenation (rSO2). METHODS In this prospective, single-centre case-control trial, we studied 32 patients undergoing elective cardiac surgery. Blood flow velocity in the middle cerebral artery (MCAv) as well as rSO2 was determined during step changes of PaCO2 between 30, 40, and 50 mmHg. Measurements were conducted on cardiopulmonary bypass during non-pulsatile and postoperatively under pulsatile blood flow at comparable test conditions. Corresponding changes of CVR and concomitant rSO2 alterations were determined for each flow mode. Each patient served as her own control. RESULTS MCAv was generally lower during hypocapnia than during normocapnia and hypercapnia (p < 0.0001). However, the MCAv/PaCO2 slope during non-pulsatile flow was 14.4 cm/s/mmHg [CI 11.8-16.9] and 10.4 cm/s/mmHg [CI 7.9-13.0] after return of pulsatility (p = 0.03). During hypocapnia, non-pulsatile CVR (4.3 ± 1.7%/mmHg) was higher than pulsatile CVR (3.1 ± 1.3%/mmHg, p = 0.01). Independent of the flow mode, we observed a decline in rSO2 during hypocapnia and a corresponding rise during hypercapnia (p < 0.0001). However, the relationship between ΔrSO2 and ΔMCAv was less pronounced during non-pulsatile flow. CONCLUSIONS Non-pulsatile perfusion is associated with enhanced cerebrovascular CVR resulting in greater relative decreases of cerebral blood flow during hypocapnia. Heterogenic microvascular perfusion may account for the attenuated ΔrSO2/ΔMCAv slope. Potential hazards related to this altered regulation of cerebral perfusion still need to be assessed. TRIAL REGISTRATION The study was retrospectively registered on October 30, 2018, with Clinical Trial.gov (NCT03732651).
Collapse
Affiliation(s)
- Cecilia Maria Veraar
- Division of Cardiothoracic and Vascular Anaesthesia and Intensive Care Medicine, Department of Anaesthesia, Intensive Care Medicine, and Pain Medicine, Vienna General Hospital, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
| | - Harald Rinösl
- Department of Anaesthesia and Intensive Care Medicine, LKH Feldkirch, Feldkirch, Austria
| | - Karina Kühn
- Department of Anaesthesia, Intensive Care Medicine and Pain Medicine, Klinikum Traunstein, Traunstein, Germany
| | - Keso Skhirtladze-Dworschak
- Division of Cardiothoracic and Vascular Anaesthesia and Intensive Care Medicine, Department of Anaesthesia, Intensive Care Medicine, and Pain Medicine, Vienna General Hospital, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
| | - Alessia Felli
- Division of Cardiothoracic and Vascular Anaesthesia and Intensive Care Medicine, Department of Anaesthesia, Intensive Care Medicine, and Pain Medicine, Vienna General Hospital, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
| | - Mohamed Mouhieddine
- Division of Cardiothoracic and Vascular Anaesthesia and Intensive Care Medicine, Department of Anaesthesia, Intensive Care Medicine, and Pain Medicine, Vienna General Hospital, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
| | - Johannes Menger
- Division of Cardiothoracic and Vascular Anaesthesia and Intensive Care Medicine, Department of Anaesthesia, Intensive Care Medicine, and Pain Medicine, Vienna General Hospital, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
| | - Ekaterina Pataraia
- Department of Neurology, Vienna General Hospital, Medical University of Vienna, Vienna, Austria
| | - Hendrik Jan Ankersmit
- Division of Thoracic Surgery, Department of Surgery, Vienna General Hospital, Medical University of Vienna, Vienna, Austria
| | - Martin Dworschak
- Division of Cardiothoracic and Vascular Anaesthesia and Intensive Care Medicine, Department of Anaesthesia, Intensive Care Medicine, and Pain Medicine, Vienna General Hospital, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
| |
Collapse
|
4
|
Nordström CH, Koskinen LO, Olivecrona M. Aspects on the Physiological and Biochemical Foundations of Neurocritical Care. Front Neurol 2017; 8:274. [PMID: 28674514 PMCID: PMC5474476 DOI: 10.3389/fneur.2017.00274] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 05/29/2017] [Indexed: 12/25/2022] Open
Abstract
Neurocritical care (NCC) is a branch of intensive care medicine characterized by specific physiological and biochemical monitoring techniques necessary for identifying cerebral adverse events and for evaluating specific therapies. Information is primarily obtained from physiological variables related to intracranial pressure (ICP) and cerebral blood flow (CBF) and from physiological and biochemical variables related to cerebral energy metabolism. Non-surgical therapies developed for treating increased ICP are based on knowledge regarding transport of water across the intact and injured blood-brain barrier (BBB) and the regulation of CBF. Brain volume is strictly controlled as the BBB permeability to crystalloids is very low restricting net transport of water across the capillary wall. Cerebral pressure autoregulation prevents changes in intracranial blood volume and intracapillary hydrostatic pressure at variations in arterial blood pressure. Information regarding cerebral oxidative metabolism is obtained from measurements of brain tissue oxygen tension (PbtO2) and biochemical data obtained from intracerebral microdialysis. As interstitial lactate/pyruvate (LP) ratio instantaneously reflects shifts in intracellular cytoplasmatic redox state, it is an important indicator of compromised cerebral oxidative metabolism. The combined information obtained from PbtO2, LP ratio, and the pattern of biochemical variables reveals whether impaired oxidative metabolism is due to insufficient perfusion (ischemia) or mitochondrial dysfunction. Intracerebral microdialysis and PbtO2 give information from a very small volume of tissue. Accordingly, clinical interpretation of the data must be based on information of the probe location in relation to focal brain damage. Attempts to evaluate global cerebral energy state from microdialysis of intraventricular fluid and from the LP ratio of the draining venous blood have recently been presented. To be of clinical relevance, the information from all monitoring techniques should be presented bedside online. Accordingly, in the future, the chemical variables obtained from microdialysis will probably be analyzed by biochemical sensors.
Collapse
Affiliation(s)
| | - Lars-Owe Koskinen
- Department of Clinical Neuroscience, Division of Neurosurgery, Umeå University, Umeå, Sweden
| | - Magnus Olivecrona
- Faculty of Health and Medicine, Department of Anesthesia and Intensive Care, Section for Neurosurgery Örebro University Hospital, Örebro University, Örebro, Sweden
- Department for Medical Sciences, Örebro University, Örebro, Sweden
| |
Collapse
|
5
|
The anti-inflammatory properties of Satureja khuzistanica Jamzad essential oil attenuate the effects of traumatic brain injuries in rats. Sci Rep 2016; 6:31866. [PMID: 27535591 PMCID: PMC4989136 DOI: 10.1038/srep31866] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 07/26/2016] [Indexed: 01/29/2023] Open
Abstract
Traumatic brain injury (TBI) is a major health concern affecting the general public as well as military personnel. However, there is no FDA-approved therapy for the treatment of TBIs. In this work, we investigated the neurotherapeutic effects of the well-known natural Iranian medicine Satureja Khuzistanica Jamzad (SKJ) essential oil (SKEO) on the outcomes of diffused experimental TBI, with particular attention paid to its anti-inflammatory and anti-apoptotic effects. Male Wistar rats were treated with doses of 50, 100 and 200 (mg/kg, i.p) SKEO after induction of diffused TBIs. The results showed that injecting SKEO (200 mg/kg) 30 minutes after TBI significantly reduced brain oedema and damage to the blood-brain barrier (BBB) and limited the post-TBI increase in intracranial pressure. The veterinary coma scale (VCS) scores significantly improved in the treatment group. Also, inflammatory marker assays showed reduced levels of TNF-α, IL-1β, and IL-6 and increased IL-10 in the treated groups. Moreover, the immunohistochemical results indicated that SKEO not only reduced neuronal death and BBB permeability but also affected astrocytic activation. Overall, our data indicate potential clinical neurological applications for SKEO.
Collapse
|
6
|
Maa T, Yeates KO, Moore-Clingenpeel M, O'Brien NF. Age-related carbon dioxide reactivity in children after moderate and severe traumatic brain injury. J Neurosurg Pediatr 2016; 18:73-8. [PMID: 27035550 DOI: 10.3171/2016.1.peds15564] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The objective of this study is to assess carbon dioxide reactivity (CO2R) in children following traumatic brain injury (TBI). METHODS This prospective observational study enrolled children younger than 18 years old following moderate and severe TBI. Thirty-eight mechanically ventilated children had daily CO2R testing performed by measuring changes in their bilateral middle cerebral artery flow velocities using transcranial Doppler ultrasonography (TCD) after a transient increase in minute ventilation. The cohort was divided into 3 age groups: younger than 2 years (n = 12); 2 to 5 years old (n = 9); and older than 5 years (n = 17). RESULTS Children younger than 2 years old had a lower mean CO2R over time. The 2-5-year-old age group had higher mean CO2R than younger patients (p = 0.01), and the highest CO2R values compared with either of the other age groups (vs > 5 years old, p = 0.046; vs < 2 years old, p = 0.002). Having a lower minimum CO2R had a statistically significant negative effect on outcome at discharge (p = 0.0413). Impaired CO2R beyond Postinjury Day 4 trended toward having an effect on outcome at discharge (p = 0.0855). CONCLUSIONS Abnormal CO2R is prevalent in children following TBI, and the degree of impairment varies by age. No clinical or laboratory parameters were identified as risk factors for impaired CO2R. Lower minimum CO2R values are associated with worse outcome at discharge.
Collapse
|
7
|
da Costa L, van Niftrik CB, Crane D, Fierstra J, Bethune A. Temporal Profile of Cerebrovascular Reactivity Impairment, Gray Matter Volumes, and Persistent Symptoms after Mild Traumatic Head Injury. Front Neurol 2016; 7:70. [PMID: 27242655 PMCID: PMC4862985 DOI: 10.3389/fneur.2016.00070] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 04/25/2016] [Indexed: 12/25/2022] Open
Abstract
Objective Increased awareness around neurocognitive deficits after mild traumatic brain injury (mTBI) has progressed the search for objective, diagnostic, and monitoring tools, yet imaging biomarkers for mTBI and recovery are not established in clinical use. It has been suggested that mTBI impairs cerebrovascular reactivity (CVR) to CO2, which could be related to post-concussive syndrome (PCS). We investigate CVR evolution after mTBI using blood-oxygen-level dependent (BOLD) magnetic resonance imaging (MRI) and possible correlation with PCS. Methods A prospective cohort of 25 mTBI patients and 18 matched controls underwent BOLD MRI CVR measurements. A subset of 19 mTBI patients underwent follow-up testing. Visits took place at a mean of 63 and 180 days after injury. Symptoms were assessed with the Sport Concussion Assessment Tool 2 (SCAT2). Symptoms, CVR and brain volume [gray matter (GM), white matter (WM), and whole brain (WB)], age, and sex, were examined between groups and longitudinally within traumatic brain injury (TBI) patients. Results Traumatic brain injury participants were 72% males, mean age being 42.7 years. Control participants were 61% with mean age of 38.7 years. SCAT2 scores tended to improve among those mTBI patients with follow-up visits (p = 0.07); however, they did not tend to recover to scores of the healthy controls. Brain volumes were not statistically different between groups at the first visit (WM p = 0.71; GM p = 0.36). In mTBI patients, there was a reduction in GM volume between visits 1 and 2 (p = 0.0046). Although mean CVR indexes were similar (WM p = 0.27; GM p = 0.36; and WB p = 0.35), the correlation between SCAT2 and CVR was negative in controls (WM-r = −0.59; p = 0.010; GM-r = −0.56; p = 0.016; brain-r = −0.58; p = 0.012) and weaker and positive in mTBI (brain-r = 0.4; p = 0.046; GM-r = 0.4; p = 0.048). SCAT2 correlated with GM volume (r = 0.5215, p = 0.0075) in mTBI but not in controls (r = 0.2945, p = 0.2355). Conclusion There is a correlation between lower GM CVR indexes and lower performance on SCAT2 in patients with mTBI, which seems to be associated with more symptoms. This correlation seems to persist well beyond 120 days. mTBI may lead to a decrease in GM volume in these patients.
Collapse
Affiliation(s)
- Leodante da Costa
- Division of Neurosurgery, Department of Surgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada; Department of Medical Imaging, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada
| | | | - David Crane
- Brain Sciences Program, Sunnybrook Research Institute , Toronto, ON , Canada
| | - Jorn Fierstra
- Division of Neurosurgery, University Hospital Zurich , Zurich , Switzerland
| | - Allison Bethune
- Division of Neurosurgery, Department of Surgery, Sunnybrook Health Sciences Centre, University of Toronto , Toronto, ON , Canada
| |
Collapse
|
8
|
Donnelly J, Budohoski KP, Smielewski P, Czosnyka M. Regulation of the cerebral circulation: bedside assessment and clinical implications. Crit Care 2016; 20:129. [PMID: 27145751 PMCID: PMC4857376 DOI: 10.1186/s13054-016-1293-6] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Regulation of the cerebral circulation relies on the complex interplay between cardiovascular, respiratory, and neural physiology. In health, these physiologic systems act to maintain an adequate cerebral blood flow (CBF) through modulation of hydrodynamic parameters; the resistance of cerebral vessels, and the arterial, intracranial, and venous pressures. In critical illness, however, one or more of these parameters can be compromised, raising the possibility of disturbed CBF regulation and its pathophysiologic sequelae. Rigorous assessment of the cerebral circulation requires not only measuring CBF and its hydrodynamic determinants but also assessing the stability of CBF in response to changes in arterial pressure (cerebral autoregulation), the reactivity of CBF to a vasodilator (carbon dioxide reactivity, for example), and the dynamic regulation of arterial pressure (baroreceptor sensitivity). Ideally, cerebral circulation monitors in critical care should be continuous, physically robust, allow for both regional and global CBF assessment, and be conducive to application at the bedside. Regulation of the cerebral circulation is impaired not only in primary neurologic conditions that affect the vasculature such as subarachnoid haemorrhage and stroke, but also in conditions that affect the regulation of intracranial pressure (such as traumatic brain injury and hydrocephalus) or arterial blood pressure (sepsis or cardiac dysfunction). Importantly, this impairment is often associated with poor patient outcome. At present, assessment of the cerebral circulation is primarily used as a research tool to elucidate pathophysiology or prognosis. However, when combined with other physiologic signals and online analytical techniques, cerebral circulation monitoring has the appealing potential to not only prognosticate patients, but also direct critical care management.
Collapse
Affiliation(s)
- Joseph Donnelly
- />Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Hills Road, Cambridge, CB2 0QQ UK
| | - Karol P. Budohoski
- />Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Hills Road, Cambridge, CB2 0QQ UK
| | - Peter Smielewski
- />Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Hills Road, Cambridge, CB2 0QQ UK
| | - Marek Czosnyka
- />Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Hills Road, Cambridge, CB2 0QQ UK
- />Institute of Electronic Systems, Warsaw University of Technology, ul. Nowowiejska 15/19, 00-665 Warsaw, Poland
| |
Collapse
|
9
|
Baccaro FG, Romano M, Ciapponi A, López-Alcalde J. Indomethacin in controlling intracranial hypertension secondary to severe traumatic brain injury. Hippokratia 2015. [DOI: 10.1002/14651858.cd011725] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Fernando G Baccaro
- Hospital "Juan A. Fernández"; Intensive Care Unit; Cerviño 3356 Buenos Aires Argentina 1425
| | - Marina Romano
- Southern American Branch of the Iberoamerican Cochrane Centre; Argentine Cochrane Centre IECS, Institute for Clinical Effectiveness and Health Policy; Dr. Emilio Ravignani 2024 Buenos Aires Capital Federal Argentina C1414CPV
| | - Agustín Ciapponi
- Institute for Clinical Effectiveness and Health Policy; Argentine Cochrane Centre IECS - Southern American Branch of the Iberoamerican Cochrane Centre; Dr. Emilio Ravignani 2024 Buenos Aires Capital Federal Argentina C1414CPV
| | - Jesús López-Alcalde
- Iberoamerican Cochrane Centre - Biomedical Research Institute Sant Pau (IIB Sant Pau); Barcelona Cataluña Spain 08041
| |
Collapse
|
10
|
Harish G, Mahadevan A, Pruthi N, Sreenivasamurthy SK, Puttamallesh VN, Keshava Prasad TS, Shankar SK, Srinivas Bharath MM. Characterization of traumatic brain injury in human brains reveals distinct cellular and molecular changes in contusion and pericontusion. J Neurochem 2015; 134:156-72. [PMID: 25712633 DOI: 10.1111/jnc.13082] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Revised: 01/07/2015] [Accepted: 02/19/2015] [Indexed: 12/22/2022]
Abstract
Traumatic brain injury (TBI) contributes to fatalities and neurological disabilities worldwide. While primary injury causes immediate damage, secondary events contribute to long-term neurological defects. Contusions (Ct) are primary injuries correlated with poor clinical prognosis, and can expand leading to delayed neurological deterioration. Pericontusion (PC) (penumbra), the region surrounding Ct, can also expand with edema, increased intracranial pressure, ischemia, and poor clinical outcome. Analysis of Ct and PC can therefore assist in understanding the pathobiology of TBI and its management. This study on human TBI brains noted extensive neuronal, astroglial and inflammatory changes, alterations in mitochondrial, synaptic and oxidative markers, and associated proteomic profile, with distinct differences in Ct and PC. While Ct displayed petechial hemorrhages, thrombosis, inflammation, neuronal pyknosis, and astrogliosis, PC revealed edema, vacuolation of neuropil, axonal loss, and dystrophic changes. Proteomic analysis demonstrated altered immune response, synaptic, and mitochondrial dysfunction, among others, in Ct, while PC displayed altered regulation of neurogenesis and cytoskeletal architecture, among others. TBI brains displayed oxidative damage, glutathione depletion, mitochondrial dysfunction, and loss of synaptic proteins, with these changes being more profound in Ct. We suggest that analysis of markers specific to Ct and PC may be valuable in the evaluation of TBI pathobiology and therapeutics. We have characterized the primary injury in human traumatic brain injury (TBI). Contusions (Ct) - the injury core displayed hemorrhages, inflammation, and astrogliosis, while the surrounding pericontusion (PC) revealed edema, vacuolation, microglial activation, axonal loss, and dystrophy. Proteomic analysis demonstrated altered immune response, synaptic and mitochondrial dysfunction in Ct, and altered regulation of neurogenesis and cytoskeletal architecture in PC. Ct displayed more oxidative damage, mitochondrial, and synaptic dysfunction compared to PC.
Collapse
Affiliation(s)
- Gangadharappa Harish
- Department of Neurochemistry, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, Karnataka, India
| | - Anita Mahadevan
- Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, Karnataka, India
| | - Nupur Pruthi
- Department of Neurosurgery, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, Karnataka, India
| | | | | | | | - Susarla Krishna Shankar
- Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, Karnataka, India
| | | |
Collapse
|
11
|
Cerebral blood flow and transcranial doppler sonography measurements of CO2-reactivity in acute traumatic brain injured patients. Neurocrit Care 2015; 20:54-9. [PMID: 22700360 DOI: 10.1007/s12028-012-9727-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
BACKGROUND Cerebral blood flow (CBF) measurements are helpful in managing patients with traumatic brain injury (TBI), and testing the cerebrovascular reactivity to CO(2) provides information about injury severity and outcome. The complexity and potential hazard of performing CBF measurements limits routine clinical use. An alternative approach is to measure the CBF velocity using bedside, non-invasive, and transcranial Doppler (TCD) sonography. This study was performed to investigate if TCD is a useful alternative to CBF in patients with severe TBI. METHOD CBF and TCD flow velocity measurements and cerebrovascular reactivity to hypocapnia were simultaneously evaluated in 27 patients with acute TBI. Measurements were performed preoperatively during controlled normocapnia and hypocapnia in patients scheduled for hematoma evacuation under general anesthesia. MAIN FINDING AND CONCLUSION Although the lack of statistical correlation between the calculated reactivity indices, there was a significant decrease in TCD-mean flow velocity and a decrease in CBF with hypocapnia. CBF and TCD do not seem to be directly interchangeable in determining CO(2)-reactivity in TBI, despite both methods demonstrating deviation in the same direction during hypocapnia. TCD and CBF measurements both provide useful information on cerebrovascular events which, although not interchangeable, may complement each other in clinical scenarios.
Collapse
|
12
|
Severe traumatic brain injury management and clinical outcome using the Lund concept. Neuroscience 2014; 283:245-55. [DOI: 10.1016/j.neuroscience.2014.06.039] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 06/17/2014] [Accepted: 06/18/2014] [Indexed: 02/04/2023]
|
13
|
Rostami E, Engquist H, Enblad P. Imaging of cerebral blood flow in patients with severe traumatic brain injury in the neurointensive care. Front Neurol 2014; 5:114. [PMID: 25071702 PMCID: PMC4083561 DOI: 10.3389/fneur.2014.00114] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 06/16/2014] [Indexed: 12/21/2022] Open
Abstract
Ischemia is a common and deleterious secondary injury following traumatic brain injury (TBI). A great challenge for the treatment of TBI patients in the neurointensive care unit (NICU) is to detect early signs of ischemia in order to prevent further advancement and deterioration of the brain tissue. Today, several imaging techniques are available to monitor cerebral blood flow (CBF) in the injured brain such as positron emission tomography (PET), single-photon emission computed tomography, xenon computed tomography (Xenon-CT), perfusion-weighted magnetic resonance imaging (MRI), and CT perfusion scan. An ideal imaging technique would enable continuous non-invasive measurement of blood flow and metabolism across the whole brain. Unfortunately, no current imaging method meets all these criteria. These techniques offer snapshots of the CBF. MRI may also provide some information about the metabolic state of the brain. PET provides images with high resolution and quantitative measurements of CBF and metabolism; however, it is a complex and costly method limited to few TBI centers. All of these methods except mobile Xenon-CT require transfer of TBI patients to the radiological department. Mobile Xenon-CT emerges as a feasible technique to monitor CBF in the NICU, with lower risk of adverse effects. Promising results have been demonstrated with Xenon-CT in predicting outcome in TBI patients. This review covers available imaging methods used to monitor CBF in patients with severe TBI.
Collapse
Affiliation(s)
- Elham Rostami
- Section of Neurosurgery, Department of Neuroscience, Uppsala University , Uppsala , Sweden ; Department of Neuroscience, Karolinska Institutet , Stockholm , Sweden
| | - Henrik Engquist
- Department of Surgical Sciences, Anaesthesiology and Intensive Care, Uppsala University , Uppsala , Sweden
| | - Per Enblad
- Section of Neurosurgery, Department of Neuroscience, Uppsala University , Uppsala , Sweden
| |
Collapse
|
14
|
Krainik A, Villien M, Troprès I, Attyé A, Lamalle L, Bouvier J, Pietras J, Grand S, Le Bas JF, Warnking J. Functional imaging of cerebral perfusion. Diagn Interv Imaging 2013; 94:1259-78. [PMID: 24011870 DOI: 10.1016/j.diii.2013.08.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The functional imaging of perfusion enables the study of its properties such as the vasoreactivity to circulating gases, the autoregulation and the neurovascular coupling. Downstream from arterial stenosis, this imaging can estimate the vascular reserve and the risk of ischemia in order to adapt the therapeutic strategy. This method reveals the hemodynamic disorders in patients suffering from Alzheimer's disease or with arteriovenous malformations revealed by epilepsy. Functional MRI of the vasoreactivity also helps to better interpret the functional MRI activation in practice and in clinical research.
Collapse
Affiliation(s)
- A Krainik
- Clinique universitaire de neuroradiologie et IRM, CHU de Grenoble, CS 10217, 38043 Grenoble cedex, France; Inserm U836, université Joseph-Fourier, site santé, chemin Fortuné-Ferrini, 38706 La Tronche cedex, France; UMS IRMaGe, unité IRM 3T recherche, CHU de Grenoble, CS 10217, 38043 Grenoble cedex 9, France.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Hanak V, Somers VK. Cardiovascular and cerebrovascular physiology in sleep. HANDBOOK OF CLINICAL NEUROLOGY 2011; 98:315-25. [PMID: 21056194 DOI: 10.1016/b978-0-444-52006-7.00019-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Viktor Hanak
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN 55905, USA.
| | | |
Collapse
|
16
|
Abstract
OBJECTIVE To determine the reliability and safety of the apneic oxygenation test to diagnose brain death for the purpose of organ donation. DATE SOURCES Published scientific literature in Medline database, organ donation guidelines and neurophysiological principles described in medical textbooks. STUDY SELECTION Articles on brain death, apnea testing, and radionuclide scintigraphy. DATA EXTRACTION AND SYNTHESIS Hypercarbia with a target Paco2 of 60 mm Hg (8.0 kPa) must be reached before apnea is deemed consistent with brain death in some clinical guidelines, whereas a level of 50 mm Hg (6.7 kPa) is required in another. However, the sensitivity and specificity of the test are doubtful because some patients have commenced spontaneous respiration >60 mm Hg (8.0 kPa) and high levels of Paco2 may cause CO2 narcosis. Furthermore, the test may be harmful if the brain stem is responsive because hypercarbia may also cause intracranial hypertension and contribute to brain damage. Although guidelines for organ donation recommend the test as an essential component of brain death diagnosis, it is often not performed or performed inadequately. Wide variation in conduct of the test has prompted calls for standardization. CONCLUSIONS : The apneic oxygenation test is unreliable in the diagnosis of brain death. It is scientifically flawed and hypothesized to cause brain death. In lieu of this test, a reliable test of brain perfusion should be mandatory, whereas the apneic oxygenation test, if performed at all, should be restricted to demonstration of apnea after brain perfusion has been shown to be absent.
Collapse
|
17
|
|
18
|
Sturnegk P, Mellergård P, Yonas H, Theodorsson A, Hillman J. Potential use of quantitative bedside CBF monitoring (Xe-CT) for decision making in neurosurgical intensive care. Br J Neurosurg 2008; 21:332-9. [PMID: 17676451 DOI: 10.1080/02688690701411574] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
During a 3-year period, mobile xenon-computerized tomography (Xe-CT) for bedside quantitative assessment of cerebral blood flow was used as an integrated tool for decision making during the care of complicated patients in our neurosurgical intensive care units (NSICU), in an attempt to make a preliminary evaluation regarding the usefulness of this method in routine work in the neurosurgical intensive care. With approximately 200 studies involving 75 patients, we identified six different categories where the use of bedside Xe-CT significantly influenced (or, with more experience, could have influenced) the decision making, or facilitated the handling of patients. These categories included identification of problems not apparent from other types of monitoring, avoidance of adverse effects from treatment, titration of standard treatments, evaluation of the vascular resistance reserve, assessment of adequate perfusion pressure and better utilization of resources from access to the bedside cerebral blood flow (CBF) technology. We conclude that quantitative bedside measurements of CBF could be an important addition to the diagnostic and monitoring arsenal of NSICU-tools.
Collapse
Affiliation(s)
- P Sturnegk
- Department of Neurosurgery, University Hospital, Linköping, Sweden
| | | | | | | | | |
Collapse
|
19
|
Puppo C, Lopez L, Farina G, Caragna E, Moraes L, Iturralde A, Biestro A. Indomethacin and cerebral autoregulation in severe head injured patients: a transcranial Doppler study. Acta Neurochir (Wien) 2007; 149:139-49; discussion 149. [PMID: 17195048 DOI: 10.1007/s00701-006-1074-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Accepted: 11/10/2006] [Indexed: 10/23/2022]
Abstract
OBJECTIVE To assess the effect of indomethacin on cerebral autoregulation, systemic and cerebral haemodynamics, in severe head trauma patients. DESIGN Prospective, controlled clinical trial, with repeated measurements. SETTINGS A 12-bed adult general intensive care unit in a third level referral university hospital. PATIENTS 16 severely head injured patients, 14 males, age range 17-60. INTERVENTIONS Indomethacin was administrated as a load plus continuous infusion. Indomethacin reactivity was assessed as the estimated cerebral blood flow change elicited by the load. Dynamic and static cerebral autoregulation tests were performed before indomethacin administration, and during its infusion. MEASUREMENTS AND MAIN RESULTS Systemic and cerebral haemodynamic changes were assessed through continuous monitoring of mean arterial pressure, transcranial Doppler cerebral blood flow velocity, intracranial pressure, cerebral perfusion pressure, and jugular venous oxygen saturation. Indomethacin loading dose was immediately followed by a cerebral blood flow median decrease of 36 or 29% (p = ns) evaluated by two different methods, by an ICP decrease and by an AVDO(2) increase from 3.52 to 6.15 mL/dL (p = 0.002). Dynamic autoregulation increased from a median of 28 to 57% (p<0.05) during indomethacin infusion; static autoregulation also increased, from a median of 72 to 89% (p = ns). CONCLUSIONS Indomethacin decreased intracranial pressure and cerebral blood flow, and increased cerebral perfusion pressure, while maintaining tissue properties of further extracting O(2). The increase in both autoregulatory values reveals an enhancement of cerebral microvasculature reactivity under indomethacin, during hypertensive and--especially--during hypotensive situations.
Collapse
Affiliation(s)
- C Puppo
- Intensive Care Unit, Clinics Hospital, Universidad de la República, Montevideo, Uruguay.
| | | | | | | | | | | | | |
Collapse
|
20
|
Rao GSU, Pillai SV. Cerebrovascular Reactivity to Carbon Dioxide in the Normal and Abnormal Cerebral Hemispheres Under Anesthesia in Patients With Frontotemporal Gliomas. J Neurosurg Anesthesiol 2006; 18:185-8. [PMID: 16799345 DOI: 10.1097/01.ana.0000211000.56151.df] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Cerebral pathology may alter the cerebrovascular reactivity to carbon dioxide (CO2). In the present study, in patients with brain tumors, we examined the cerebral vascular reactivity to CO2 in the cerebral hemispheres with and without tumors under intravenous and inhalational anesthesia. Twenty-nine patients undergoing craniotomy for frontotemporal gliomas were randomized to receive intravenous anesthesia with propofol or inhalational anesthesia with isoflurane. Cerebral blood flow velocity in the middle cerebral artery (VMCA) and pulsatality index were measured under normocapnia and hypocapnia in the normal cerebral hemisphere and the hemisphere with tumor. Hypocapnia significantly decreased the VMCA in both the cerebral hemispheres under both the anesthetic techniques (P < 0.006). The percentage change in VMCA was similar between the hemispheres with and without tumor both under isoflurane (3.45 +/- 4.11% on the normal side and 2.91 +/- 2.40% on the tumor side; mean difference 0.54 +/- 1.31%; 95% CI -2.18 to +3.27) and propofol anesthesia (2.32 +/- 2.64% on the normal side and 1.69 +/- 4.04% on the tumor side; mean difference 0.63 +/- 1.2%; 95% CI -1.83 to +3.10). The changes in pulsatality index also were not significantly different between the hemispheres. In conclusion, cerebrovascular response to hypocapnia is similar between the normal and the abnormal cerebral hemispheres both under intravenous and inhalational anesthesia.
Collapse
|
21
|
Abstract
BACKGROUND Cerebral edema is a potentially devastating complication of various acute neurologic disorders. Its successful treatment may save lives and preserve neurologic function. REVIEW SUMMARY Different pathophysiological mechanisms are responsible for the formation of cytotoxic and vasogenic edema. Yet, these 2 types of edema often coexist and their treatment tends to overlap, with the exception of corticosteroids, which should be only used to ameliorate vasogenic edema. Currently available to control brain swelling include osmotic agents (with emphasis on mannitol and hypertonic saline solutions), corticosteroids, hyperventilation, sedation (propofol, barbiturates), neuromuscular paralysis, hypothermia, and surgical interventions. This article discusses the indications, advantages, and limitations of each treatment modality following an evidence-based approach. CONCLUSIONS The therapy for brain edema remains largely empirical. More research aimed at enhancing our understanding of the pathophysiology of cerebral edema is needed to identify new and more effective forms of treatment.
Collapse
|
22
|
Nordström CH. Physiological and biochemical principles underlying volume-targeted therapy--the "Lund concept". Neurocrit Care 2005; 2:83-95. [PMID: 16174975 DOI: 10.1385/ncc:2:1:083] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The optimal therapy of sustained increase in intracranial pressure (ICP) remains controversial. The volume-targeted therapy ("Lund concept") discussed in this article focuses on the physiological volume regulation of the intracranial compartments. The balance between effective transcapillary hydrostatic and osmotic pressures constitutes the driving force for transcapillary fluid exchange. The low permeability for sodium and chloride combined with the high crystalloid osmotic pressure (approximately 5700 mmHg) on both sides of the blood-brain barrier (BBB) counteracts fluid exchange across the intact BBB. Additionally, variations in systemic blood pressure generally are not transmitted to these capillaries because cerebral intracapillary hydrostatic pressure (and blood flow) is physio-logically tightly autoregulated. Under pathophysiological conditions, the BBB may be partially disrupted. Transcapillary water exchange is then determined by the differences in hydrostatic and colloid osmotic pressure between the intra- and extracapillary compartments. Pressure autoregulation of cerebral blood flow is likely to be impaired in these conditions. A high cerebral perfusion pressure accordingly increases intracapillary hydrostatic pressure and leads to increased intracerebral water content and an increase in ICP. The volume-targeted "Lund concept" has been evaluated in experimental and clinical studies to examine the physiological and biochemical (utilizing intracerebral microdialysis) effects, and the clinical experiences have been favorable.
Collapse
|
23
|
Abstract
The optimal therapy of sustained increase in intracranial pressure (ICP) is still controversial. The "Lund concept" is based on the physiological volume regulation of the intracranial compartments. In addition to its other functions the blood-brain barrier (BBB) is the most important regulator of brain volume. Water exchange across the intact BBB is counteracted by the low permeability to crystalloids (mainly Na+ and Cl-) combined with the high osmotic pressure (5,700 mmHg) on both sides of the BBB. If the BBB is disrupted transcapillary water transport will be determined by the differences in hydrostatic and colloid osmotic pressure between the intra- and extracapillary compartments. Under pathological conditions pressure autoregulation of cerebral blood flow is often impaired and intracapillary hydrostatic pressure will depend on variations in systemic blood pressure. The "Lund concept" can be summarized in four paragraphs: I. Reduction of stress response and cerebral energy metabolism; II. Reduction of capillary hydrostatic pressure; III. Maintenance of colloid osmotic pressure and control of fluid balance; IV. Reduction of cerebral blood volume. The efficacy of the treatment protocol has been evaluated in experimental and clinical studies regarding the physiological and biochemical (utilizing intracerebral microdialysis) effects. The clinical experiences have been favourable.
Collapse
Affiliation(s)
- C H Nordström
- Department of Neurosurgery, Lund University Hospital, Lund, Sweden.
| |
Collapse
|
24
|
Nordström CH. Volume-targeted therapy of increased intracranial pressure. ACTA NEUROCHIRURGICA. SUPPLEMENT 2004; 86:355-60. [PMID: 14753468 DOI: 10.1007/978-3-7091-0651-8_76] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Fluid exchange across the intact blood-brain barrier (BBB) is counteracted by the low permeability to crystalloids (mainly Na+ and Cl-) combined with the high osmotic pressure (5,700 mm Hg) on both sides of the BBB. If the BBB is disrupted transcapillary water transport will be determined by the differences in hydrostatic and colloid osmotic pressure between the intra- and extracapillary compartments. Under these pathological conditions pressure autoregulation of cerebral blood flow is likely to be impaired and intracapillary hydrostatic pressure will depend on variations in systemic blood pressure. The volume targeted "Lund concept" can be summarized under four headings: A. Reduction of stress response and cerebral energy metabolism: B. Reduction of capillary hydrostatic pressure; C. Maintenance of colloid osmotic pressure and control of fluid balance: D. Reduction of cerebral blood volume. The efficacy of the protocol has been evaluated in experimental and clinical studies regarding the physiological and biochemical (utilizing intracerebral microdialysis) effects and the clinical experiences have been favourable.
Collapse
Affiliation(s)
- C H Nordström
- Department of Neurosurgery, Lund University Hospital, Lund, Sweden.
| |
Collapse
|
25
|
Johnston AJ, Steiner LA, Gupta AK, Menon DK. Cerebral oxygen vasoreactivity and cerebral tissue oxygen reactivity. Br J Anaesth 2003; 90:774-86. [PMID: 12765894 DOI: 10.1093/bja/aeg104] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
There has long been an appreciation that cerebral blood flow is modulated to ensure adequate cerebral oxygen delivery in the face of systemic hypoxaemia. There is increasing appreciation of the modulatory role of hyperoxia in the cerebral circulation and a consideration of the effects of such modulation on the maintenance of cerebral tissue oxygen concentration. These newer findings are particularly important in view of the fact that cerebrovascular and tissue oxygen responses to hyperoxia may change in disease. Such alterations provide important insights into pathophysiological mechanisms and may provide novel targets for therapy. However, before the modulatory effects of hyperoxia can be used for diagnosis, to predict prognosis or to direct therapy, a more detailed analysis and understanding of the physiological concepts behind this modulation are required, as are the limitations of the measurement tools used to define the modulation. This overview summarizes the available information in this area and suggests some avenues for further research.
Collapse
Affiliation(s)
- A J Johnston
- University of Cambridge Department of Anaesthetics, Box 93 and Academic Neurosurgery, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK.
| | | | | | | |
Collapse
|
26
|
Johnston AJ, Steiner LA, Balestreri M, Gupta AK, Menon DK. Hyperoxia and the cerebral hemodynamic responses to moderate hyperventilation. Acta Anaesthesiol Scand 2003; 47:391-6. [PMID: 12694135 DOI: 10.1034/j.1399-6576.2003.00078.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND A reduction in the arterial partial pressure of CO2 (PaCO2) leads to a rapid reduction in cerebral blood flow (CBF). However, despite continuing hypocapnia there is secondary recovery of CBF over time as a result of increases in lactic acid production. Hyperoxia is thought to modulate the production of lactic acid. This study examined the kinetics of middle cerebral artery flow velocity (MCA FV) reduction during hyperventilation, and its modulation by hyperoxia. METHODS Cerebral blood flow was assessed using transcranial Doppler ultrasound in nine healthy, awake human volunteers. Subjects were ventilated, via a mouthpiece, to achieve a stable end-tidal CO2 (PETCO2). After a 20-min baseline period the minute volume on the ventilator was passively increased by approximately 20% to reduce PETCO2 by 0.75-1 kPa. After a 10-min stabilization period the new PETCO2 level was maintained at a constant level for 20 min, and MCA FV recovery was measured during this 20-min period. Subjects undertook the protocol breathing air and breathing 100% oxygen. RESULTS The PETCO2 level was (mean +/- SD) 4.9 +/- 0.4 kPa (normoxia baseline), 4.0 +/- 0.3 kPa (normoxia hyperventilation), 4.6 +/- 0.4 kPa (hyperoxia baseline) and 3.9 +/- 0.4 kPa (hyperoxia hyperventilation). CO2 reactivity was significantly lower with normoxia than hyperoxia (16.5 +/- 3.8 vs. 21.2 +/- 4.6 % kPa-1; P< 0.05). Middle cerebral artery FV recovery was significantly more rapid with normoxia than hyperoxia (0.23 +/- 0.17 vs. 0.08 +/- 0.1 % baseline min-1; P< 0.01). CONCLUSIONS Our results suggest that cerebral hemodynamic responses to moderate hyperventilation are different in normoxic and hyperoxic conditions. Clinical assessment of CO2 reactivity and CBF recovery during hyperventilation should take the degree of arterial oxygenation into account.
Collapse
Affiliation(s)
- A J Johnston
- Department of Anaesthetics, Addenbrooke's Hospital, University of Cambridge, Academic Neurosurgery, Addenbrooke's Hospital, Cambridge, UK.
| | | | | | | | | |
Collapse
|
27
|
Steinmeier R, Bauhuf C, Hübner U, Hofmann RP, Fahlbusch R. Continuous cerebral autoregulation monitoring by cross-correlation analysis: evaluation in healthy volunteers. Crit Care Med 2002; 30:1969-75. [PMID: 12352028 DOI: 10.1097/00003246-200209000-00004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE In a former study, we applied cross-correlation (CC) analysis to recordings of arterial blood pressure (BP), intracranial pressure (ICP), and intracranial blood flow velocity (FV). A lack of significant time delay and a positive correlation coefficient of slow oscillations between these parameters was interpreted as indicative of impaired cerebral autoregulation, whereas a significant time delay and a negative correlation was regarded as preserved autoregulation. To test this hypothesis, cross-correlation was applied on recordings of BP and FV (CC [BP --> FV]) in healthy volunteers with a presumably preserved cerebral autoregulation. DESIGN Study of a diagnostic test. SUBJECTS A total of 17 healthy volunteers. MEASUREMENTS AND MAIN RESULTS BP was recorded by using a tonometric device, and bilateral FV in the middle cerebral arteries (MCA) was measured by transcranial Doppler sonography. Signals were sampled at a resting horizontal position for 29 mins. Cluster analysis showed a mean +/- sd time delay for CC [BP --> FV(MCA right)] of 6.45 +/- 2.1 secs, and for CC [BP --> FV(MCA left) ] of 6.09 +/- 1.8 secs. The mean correlation coefficient was -.33 +/-.17 for the left and -.36 +/-.09 for the right side. In about 30%, differing results with a correlation coefficient between -.2 and.2 and a time delay near zero were found. Cross-correlation between left and right FV showed a mean time delay of 0.09 +/- 0.18 secs, with a mean correlation coefficient of.82 +/-.16. CONCLUSION Spontaneous slow oscillations of BP and FV were detected, and cross-correlation analysis showed a negative correlation and a positive time delay in about 70% of the examinations. These findings corroborate the hypothesis that CC [BP --> FV] might be able to assess the status of cerebral autoregulation continuously. The observed time delay between BP and FV oscillations is in good agreement with former studies on the dynamic properties of cerebral autoregulation.
Collapse
Affiliation(s)
- Ralf Steinmeier
- Department of Neurosurgery, University of Erlangen-Nürnberg, Erlangen, Germany.
| | | | | | | | | |
Collapse
|
28
|
Grände PO, Asgeirsson B, Nordström CH. Volume-targeted therapy of increased intracranial pressure: the Lund concept unifies surgical and non-surgical treatments. Acta Anaesthesiol Scand 2002; 46:929-41. [PMID: 12190792 DOI: 10.1034/j.1399-6576.2002.460802.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Opinions differ widely on the various treatment protocols for sustained increase in intracranial pressure (ICP). This review focuses on the physiological volume regulation of the intracranial compartments. Based on these mechanisms we describe a protocol called 'volume-targeted' ('Lund concept') for treatment of increased ICP. The driving force for transcapillary fluid exchange is determined by the balance between effective transcapillary hydrostatic and osmotic pressures. Fluid exchange across the intact blood-brain barrier (BBB) is counteracted by the low permeability to crystalloids (mainly Na+ and Cl-) combined with the high osmotic pressure (5500 mmHg) on both sides of the BBB. This contrasts to most other capillary regions where the osmotic pressure is mainly derived from the plasma proteins (approximately 25 mmHg). Accordingly, the level of the cerebral perfusion pressure (CPP) is of less importance under physiological conditions. In addition cerebral intracapillary hydrostatic pressure (and cerebral blood flow) is physiologically tightly autoregulated, and variations in systemic blood pressure are generally not transmitted to these capillaries. If the BBB is disrupted, transcapillary water transport will be determined by the differences in hydrostatic and colloid osmotic pressure between the intra- and extracapillary compartments. Under these pathological conditions, pressure autoregulation of cerebral blood flow is likely to be impaired and intracapillary hydrostatic pressure will depend on variations in systemic blood pressure. The volume-targeted 'Lund concept' can be summarized under four headings: (1) Reduction of stress response and cerebral energy metabolism; (2) reduction of capillary hydrostatic pressure; (3) maintenance of colloid osmotic pressure and control of fluid balance; and (4) reduction of cerebral blood volume. The efficacy of the protocol has been evaluated in experimental and clinical studies regarding the physiological and biochemical (utilizing intracerebral microdialysis) effects, and the clinical experiences have been favorable.
Collapse
Affiliation(s)
- P-O Grände
- Department of Anesthesiology and Intensive Care, Lund University Hospital, Sweden
| | | | | |
Collapse
|
29
|
Vavilala MS, Lee LA, Lam AM. Cerebral blood flow and vascular physiology. ANESTHESIOLOGY CLINICS OF NORTH AMERICA 2002; 20:247-64, v. [PMID: 12165993 DOI: 10.1016/s0889-8537(01)00012-8] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The cerebral circulation is tightly regulated to meet the brain's metabolic demands. Although the mechanism is not fully understood, the major physiologic influences on cerebral blood flow have been well documented. In this chapter the basic vascular anatomy, and physiologic control of the cerebral circulation are reviewed. Clinical implications are emphasized.
Collapse
Affiliation(s)
- Monica S Vavilala
- Department of Anesthesiology, Harborview Medical Center, Box 359724, 325 Ninth Avenue, Seattle, WA 98104, USA
| | | | | |
Collapse
|
30
|
Eker C, Hagstadius S, Lindén A, Schalén W, Nordström CH. Neuropsychological assessments in relation to CBF after severe head injuries. Acta Neurol Scand 2001; 104:142-7. [PMID: 11551233 DOI: 10.1034/j.1600-0404.2001.00345.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To determine whether neuropsychological outcome is related to cerebral blood flow (CBF) early in the recovery phase. MATERIAL AND METHODS Twelve consecutive patients (mean age of 30 years, range 15-48 years) with severe traumatic brain injuries were subjected to a neuropsychological test battery at admission to the rehabilitation unit and after 3, 6 and 12 months. CBF measurements were performed at admission and 6 and 12 months later with a high-resolution, two-dimensional regional cerebral blood flow system with 254 stationary detectors after 1 min of (133)Xe inhalation (70-100 MBq/l). RESULTS AND CONCLUSION Mean CBF values were within normal range already in the early post-acute phase and remained virtually unchanged during the first year of rehabilitation. A correlation was found between the individual CBF level and neuropsychological outcome 1 year after injury, particularly with regard to verbal memory capacity, reasoning capacity, and information processing speed.
Collapse
Affiliation(s)
- C Eker
- Department of Clinical Neuroscience, Lund University Hospital, S-221 85 Lund, Sweden
| | | | | | | | | |
Collapse
|
31
|
Payen JF, Briot E, Tropres I, Julien-Dolbec C, Montigon O, Decorps M. Regional cerebral blood volume response to hypocapnia using susceptibility contrast MRI. NMR IN BIOMEDICINE 2000; 13:384-391. [PMID: 11114061 DOI: 10.1002/1099-1492(200011)13:7<384::aid-nbm655>3.0.co;2-v] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We used steady-state susceptibility contrast MRI to evaluate the regional cerebral blood volume (rCBV) response to hypocapnia in anesthetised rats. The rCBV was determined in the dorsoparietal neocortex, the corpus striatum, the cerebellum, as well as blood volume in extracerebral tissue (group 1). In addition, we used laser-Doppler flow (LDF) measurements in the left dorsoparietal neocortex (group 2), to correlate changes in CBV and in cerebral blood flow. Baseline values, expressed as a percentage of blood volume in each voxel, were higher in the brain regions than in extracerebral tissue. Hypocapnia (P(a)CO(2) approximately 25 mmHg) resulted in a significant decrease in CBV in the cerebellum (-17 +/- 9%), in the corpus striatum (-15 +/- 6%) and in the neocortex (-12 +/- 7%), compared to the normocapnic CBV values (group 1). These changes were in good agreement with the values obtained using alternative techniques. No significant changes in blood volume were found in extracerebral tissue. The CBV changes were reversed during the recovery period. In the left dorsoparietal neocortex, the reduction in LDF (group 2) induced by hypocapnia (-21 +/- 8%) was in accordance with the values predicted by the Poiseuille's law. We conclude that rCBV changes during CO(2) manipulation can be accurately measured by susceptibility contrast MRI. Abbreviations used: ANOVA analysis of variance CBF cerebral blood flow CBV cerebral blood volume CPMG Carr-Purcell-Meiboom-Gill FiO(2) fractional inspired oxygen ICP intracranial pressure LDF laser-Doppler flow MABP mean arterial blood pressure MRI magnetic resonance imaging MTT mean transit time PaCO(2) arterial partial pressure of carbon dioxide PaO(2) arterial partial pressure of oxygen PET positron emission tomography rCBV regional cerebral blood volume SPECT single-photon emission computed tomography
Collapse
Affiliation(s)
- J F Payen
- Unité mixte INSERM-Université Joseph Fourier: U438, LRC CEA, H opital Albert Michallon, BP 217, 38043 Grenoble, France.
| | | | | | | | | | | |
Collapse
|
32
|
|
33
|
Eker C, Asgeirsson B, Grände PO, Schalén W, Nordström CH. Improved outcome after severe head injury with a new therapy based on principles for brain volume regulation and preserved microcirculation. Crit Care Med 1998; 26:1881-6. [PMID: 9824083 DOI: 10.1097/00003246-199811000-00033] [Citation(s) in RCA: 147] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To assess the new "Lund therapy" of posttraumatic brain edema, based on principles for brain-volume regulation and improved microcirculation. DESIGN A prospective, nonrandomized outcome study over a 5-yr period on severely head-injured patients with increased intracranial pressure, comparing the results with a historical control group with the same selection criteria for patients who were treated according to conventional principles. SETTING General intensive care unit of a university hospital. PATIENTS Fifty-three consecutive head-injured patients with a Glasgow Coma Score of <8, and with increased intracranial pressure (>25 mm Hg), despite conventional treatment. INTERVENTIONS Interstitial fluid resorption was obtained by lowering intracapillary hydrostatic pressure, by preserving normal colloid osmotic pressure, and by maintaining a normovolemic (normal albumin/serum and hemoglobin/serum), not overtransfused patient. Intracapillary pressure was reduced by the combination of precapillary vasoconstriction (low-dose thiopental, dihydroergotamine) and reduction of mean arterial pressure, the latter attained with a beta1-antagonist (metoprolol 0.2 to 0.3 mg/kg/24 hrs iv) and an alpha2-agonist (clonidine 0.4 to 0.8 microg/kg x 4 to 6 iv). Clonidine, in combination with normovolemia, also improves microcirculation by reducing catecholamines in plasma. Intracranial blood volume was reduced by arterial (low-dose thiopental sodium and dihydroergotamine) and large-vein (dihydroergotamine) vasoconstriction. The start dose of dihydroergotamine (maximum 0.9 microg/kg/hr) was successively reduced toward discontinuation within 4 to 5 days. MEASUREMENTS AND MAIN RESULTS There were 8% of patients who died and the neurologic conditions of 13% remained severely damaged, compared with 47% and 11%, respectively, for the control group. CONCLUSIONS The low mortality compared with previous outcome studies strongly indicates that this therapy improves outcome for severe head injuries. However, a randomized, controlled study is needed to reach general acceptance of this new therapy.
Collapse
Affiliation(s)
- C Eker
- Department of Rehabilitation, Lund University Hospital, Sweden
| | | | | | | | | |
Collapse
|
34
|
Ichai C, Ciais JF, Grimaud D. [The internal environment and intracranial hypertension]. ANNALES FRANCAISES D'ANESTHESIE ET DE REANIMATION 1998; 16:435-44. [PMID: 9750595 DOI: 10.1016/s0750-7658(97)81476-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intracranial pressure depends on cerebral tissue volume, cerebrospinal fluid volume (CSFV) and cerebral blood volume (CBV). Physiologically, their sum is constant (Monro-Kelly equation) and ICP remains stable. When the blood brain barrier (BBB) is intact, the volume of cerebral tissue depends on the osmotic pressure gradient. When it is injured, water movements across the BBB depend on the hydrostatic pressure gradient. CBV depends essentially on cerebral blood flow (CBF), which is strongly regulated by cerebral vascular resistances. In experimental studies, a decrease in oncotic pressure does not increase cerebral oedema and intracranial hypertension (ICHT). On the other hand, plasma hypoosmolarity increases cerebral water content and therefore ICP, if the BBB is intact. If it is injured, neither hypoosmolarity nor hypooncotic pressure modify cerebral oedema. Therefore, all hypotonic solutes may aggravate cerebral oedema and are contra-indicated in case of ICHT. On the other hand, hypooncotic solutes do not modify ICP. The osmotic therapy is one of the most important therapeutic tools for acute ICHT. Mannitol remains the treatment of choice. It acts very quickly. An i.v. perfusion of 0.25 g.kg-1 is administered over 20 minutes when ICP increases. Hypertonic saline solutes act in the same way, however they are not more efficient than mannitol. CO2 is the strongest modulating factor of CBF. Hypocapnia, by inducing cerebral vasoconstriction, decreases CBF and CBV. Hyperventilation is an efficient and rapid means for decreasing ICP. However, it cannot be used systematically without an adapted monitoring, as hypocapnia may aggravate cerebral ischaemia. Hyperthermia is an aggravating factor for ICHT, whereas moderate hypothermia seems to be beneficial both for ICP and cerebral metabolism. Hyperglycaemia has no direct effect on cerebral volume, but it may aggravate ICHT by inducing cerebral lactic acidosis and cytotoxic oedemia. Therefore, infusion of glucose solutes is contra-indicated in the first 24 hours following head trauma and blood glucose concentration must be closely monitored and controlled during ICHT episodes.
Collapse
Affiliation(s)
- C Ichai
- Département d'anesthésie-réanimation, hôpital Saint-Roch, Nice, France
| | | | | |
Collapse
|
35
|
ter Minassian A, Melon E, Leguerinel C, Lodi CA, Bonnet F, Beydon L. Changes in cerebral blood flow during PaCO2 variations in patients with severe closed head injury: comparison between the Fick and transcranial Doppler methods. J Neurosurg 1998; 88:996-1001. [PMID: 9609293 DOI: 10.3171/jns.1998.88.6.0996] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECT The aim of this study was to reassess whether middle cerebral artery blood flow velocity (MCAv) variations measured by transcranial Doppler ultrasonography during acute PaCO2 manipulation adequately reflect cerebral blood flow (CBF) changes in patients with severe closed head injury. METHODS The study was performed by comparing MCAv variations to changes in CBF as assessed by measurements of the difference in the arteriovenous content in oxygen (AVDO2). The authors initiated 35 CO2 challenges in 12 patients with severe closed head injury during the acute stage. By simultaneous recording of systemic and cerebral hemodynamic parameters, 105 AVDO2 measurements were obtained. Patients were stratified into two groups, "high" and "low," with respect to whether their resting values of MCAv were greater than 100 cm/second during moderate hyperventilation. Four patients displayed an elevated MCAv, which was related to vasospasm in three cases and to hyperemia in one case. The PaCO2 and intracranial pressure levels were not different between the two groups. The slope of the regression line between 1 divided by the change in (delta)AVDO2 and deltaMCAv was not different from identity in the low group (1/deltaAVDO2 = 1.08 x deltaMCAv - 0.07, r = 0.93, p < 0.001) and significantly differed (p < 0.05) from the slope of the high group (1/deltaAVDO2 = 1.46 x deltaMCAv - 0.4, r = 0.83, p < 0.001). CONCLUSIONS In patients with severe closed head injury, MCAv variations adequately reflect CBF changes as assessed by AVDO2 measurements in the absence of a baseline increase in MCAv. These observations indicate that both moderate variations in PaCO2 and variations in cerebral perfusion pressure do not act noticeably on the diameter of the MCA. The divergence from the expected relationship in the high group seems to be due to the heterogeneity of CO2-induced changes in cerebrovascular resistance between differing arterial territories.
Collapse
Affiliation(s)
- A ter Minassian
- Department of Anesthesia, Hôpital Henri Mondor, Créteil, France.
| | | | | | | | | | | |
Collapse
|
36
|
Paolin A, Rodriguez G, Betetto M, Simini G. Cerebral hemodynamic response to CO2 after severe head injury: clinical and prognostic implications. THE JOURNAL OF TRAUMA 1998; 44:495-500. [PMID: 9529177 DOI: 10.1097/00005373-199803000-00012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To study the cerebrovascular reactivity to CO2 after severe head injury to establish the clinical and prognostic relevance of CO2 reactivity. METHODS Cerebrovascular reactivity to CO2 was studied in 20 patients with severe head injuries at 3.0+/-1.8 days after trauma onset. Two cerebral blood flow studies were performed to measure CO2 reactivity: the first study in a condition of normocapnia and the second study in a condition of relative hypocapnia. RESULTS Global reactivity was superimposable to that found in awake, normocapnic subjects and did not correlate with age and Glasgow Coma Scale score but was dependent on the type of brain lesion. Moreover, reactivity correlated with outcome in patients studied after the first 3 days after trauma. CONCLUSIONS Our data suggest that cerebrovascular reactivity is (a) almost preserved after a severe head injury; (b) significantly influenced by type of brain lesion; (c) prognostically relevant only in patients studied after the first 3 days after trauma.
Collapse
Affiliation(s)
- A Paolin
- Anaesthesia and Critical Care Department, S. Maria dei Battuti Hospital, Treviso, Italy
| | | | | | | |
Collapse
|
37
|
Kirkeby OJ, Rise IR, Risöe C. Local variations in the cerebral microcirculatory response to hypercapnia and haemorrhage. Acta Neurochir (Wien) 1997; 139:981-6. [PMID: 9401661 DOI: 10.1007/bf01411310] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This study evaluates local variations of the cerebral vasomotor responses to hypercapnia and haemorrhagic hypotension in a pig model. Four laser Doppler flow probes were used in each pig. There was considerable variation in laser Doppler signals between the four probes in baseline recordings. The increases in flow after CO2 administration in 7 pigs had a mean coefficient of variation of 0.43 +/- 0.31, and the flow changes after blood loss in another 7 pigs had a mean coefficient of variation of 0.45 +/- 0.34. The range of flow changes within each animal was large; the probe with the highest CO2 response showed on the average a 273% +/- 157% larger CO2 response than the probe with the lowest CO2 response. Correspondingly, the probe with the best preserved blood flow after blood loss had on the average a flow value of 93% +/- 12% of the baseline value, while the probe that changed most with haemorrhage had a flow value of 44% +/- 24% of the baseline value. Single laser Doppler recordings have been used for the monitoring of cerebral blood flow in neurosurgical critical care, but our results suggest that a single laser Doppler flow probe is not an adequate method to monitor vasoreactivity in neurosurgical patients because flow signals from one probe may be unrepresentative for other sites in the brain.
Collapse
Affiliation(s)
- O J Kirkeby
- Institute for Surgical Research, The National Hospital, Oslo, Norway
| | | | | |
Collapse
|
38
|
Nilsson F, Nilsson T, Edvinsson L, Björkman S, Nordström CH. Effects of dihydroergotamine and sumatriptan on isolated human cerebral and peripheral arteries and veins. Acta Anaesthesiol Scand 1997; 41:1257-62. [PMID: 9422289 DOI: 10.1111/j.1399-6576.1997.tb04641.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Pharmacological cerebral vasoconstriction has recently been suggested as treatment for patients with increased intracranial pressure (ICP) after severe traumatic brain lesions. Hypothetically, a moderate constriction of precapillary resistance vessels might be advantageous since it decreases intracapillary blood pressure, and a contraction of cerebral veins might effectively reduce intracranial blood volume and ICP. This report examines the in vitro effects of two vasoconstrictors, dihydroergotamine (DHE) and sumatriptan, which may be considered for treatment of increased ICP. METHODS The reactivity of isolated small human cerebral subcutaneous and omental arteries and veins were studied during exposure to different concentrations of DHE and sumatriptan. RESULTS Both sumatriptan and DHE induced concentration-dependent contractions in human cerebral arteries and veins and 50% of maximum contractions were obtained at significantly lower concentrations of DHE than of sumatriptan. The maximum contraction of cerebral arteries was significantly higher with sumatriptan than with DHE. Both drugs caused contractions of subcutaneous arteries at concentrations of 10(-7)-10(-6)M, which is within the therapeutic concentration range of sumatriptan, while no effect was obtained in omental vessels. CONCLUSIONS Both DHE and sumatriptan cause contraction of isolated human cortical arteries and veins at very low concentrations. The differences observed between the two drugs may be explained by the fact that DHE is an alpha-adrenergic as well as a 5-HT agonist while sumatriptan acts specifically on 5-HT receptors. The study supports the hypothesis underlying the use of DHE for the treatment of increased ICP in patients with severe traumatic brain lesions.
Collapse
Affiliation(s)
- F Nilsson
- Department of Anaesthesia and Intensive Care, and Experimental Research, Malmö University Hospital, Sweden
| | | | | | | | | |
Collapse
|
39
|
Grände PO, Asgeirsson B, Nordström CH. Physiologic principles for volume regulation of a tissue enclosed in a rigid shell with application to the injured brain. THE JOURNAL OF TRAUMA 1997; 42:S23-31. [PMID: 9191692 DOI: 10.1097/00005373-199705001-00005] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Preservation of a high cerebral perfusion (mean arterial) pressure to prevent ischemia has become the primary focus during treatment of severe head trauma because ischemia is favored as a triggering mechanism behind intracellular brain edema development and poor outcome. A high cerebral perfusion pressure, however, simultaneously may increase the hydrostatic vasogenic edema. The present paper evaluates the mechanisms behind the vasogenic edema by analyzing the physiologic hemodynamic mechanisms controlling the volume of a tissue that is enclosed in a rigid shell, possesses capillaries permeable for solutes, and has depressed autoregulation. RESULTS AND CONCLUSIONS We contend that in the long run, the interstitial volume in such a tissue can be reduced only through reduction in arterial inflow pressure providing an otherwise optimal therapy to improve microcirculation. Therefore we argue, in contrast to the conventional view, that antihypertensive and antistress therapy may be of value by reducing the interstitial tissue volume during treatment of brain edema, and that the problem with ischemia during such therapy can be handled when considering an otherwise optimal intensive care. These physiologic principles of interstitial tissue volume regulation form the basic concept for the "Lund therapy" of severe head injuries, which is a new and controversial therapy of posttraumatic brain edema.
Collapse
Affiliation(s)
- P O Grände
- Department of Anaesthesia and Intensive Care, University Hospital and University of Lund, Sweden
| | | | | |
Collapse
|
40
|
Ono Y, Morikawa S, Inubushi T, Shimizu H, Yoshimoto T. T2*-weighted magnetic resonance imaging of cerebrovascular reactivity in rat reversible focal cerebral ischemia. Brain Res 1997; 744:207-15. [PMID: 9027380 DOI: 10.1016/s0006-8993(96)01079-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Cerebrovascular carbon dioxide (CO2) reactivity is an important hemodynamic index in cerebrovascular disease. In the present study T2*-weighted magnetic resonance image (T2* WI) was evaluated as a non-invasive method to investigate changes in CO2 reactivity. Fourteen rats were subjected to permanent or, 30 and 90 min of temporary middle cerebral artery occlusion. A series of T2* WIs and diffusion-weighted magnetic resonance images (DWI) was performed hourly under normo- and hypercapnic conditions. Triphenyltetrazolium chloride (TTC) staining of brain sections was obtained at the end of experiment to evaluate ischemic damage. During ischemia, a 4-6% signal increase upon hypercapnia was observed on T2* WI in the non-ischemic hemisphere, while no such reactivity was seen in the putamen and cortex ipsilateral to the MCA occlusion. After reperfusion, CO2 reactivity recovered in the putamen and cortex in the 30 min ischemia group and in the cortex alone of the 90 min ischemia groups. The areas with irreversible CO2 reactivity dysfunction coincidentally revealed no recovery on DWI and lack of TTC staining. The results indicate that T2* WI can be used to monitor changes in CO2 reactivity after various ischemic insults that may indicate tissue viability.
Collapse
Affiliation(s)
- Y Ono
- Department of Neurosurgery, Tohoku University School of Medicine, Sendai, Japan
| | | | | | | | | |
Collapse
|
41
|
Smielewski P, Czosnyka M, Kirkpatrick P, McEroy H, Rutkowska H, Pickard JD. Assessment of cerebral autoregulation using carotid artery compression. Stroke 1996; 27:2197-203. [PMID: 8969780 DOI: 10.1161/01.str.27.12.2197] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND AND PURPOSE A simple method of testing cerebral autoregulation by observing transcranial Doppler changes in middle cerebral artery flow velocity (FV) during a brief ipsilateral carotid artery compression (the transient hyperemic response test) was studied in 11 normal healthy volunteers. The aim of this study was to assess the reliability of the method and to compare derived autoregulatory indices with those of a standard noninvasive test of autoregulation, Aaslid's leg-cuff test. METHODS Volunteers were subjected to repeated carotid compressions and leg-cuff tests at different levels of CO2. Hypercapnia was induced using inhalation of a mixture of 5% CO2 in air. Hypocapnia was induced by moderate hyperventilation. To assess the influence of the duration of carotid compression, a series of carotid compressions lasting 3, 4, 5, 7, and 9 seconds were performed in random sequence. Monitored parameters included ipsilateral FV, end-tidal CO2, and arterial blood pressure. The transient hyperemic response ratio (THRR), calculated as the maximum increase of FV divided by baseline values after release of the carotid compression, was taken as the autoregulation index. This index was compared with the rate of autoregulation index derived from the leg-cuff test. RESULTS Both tests were significantly associated with end-tidal CO2 (ANOVA, P < .000001 for both carotid compression and cuff test). There was a linear correlation between THRR and autoregulation index (r = .86). However, the reproducibility of the THRR was more consistent than for the autoregulation index from single tests (13% versus 46%, respectively; P < .0001). Although the influence of the duration of carotid compression on THRR values was significant for carotid compressions lasting up to 5 seconds, there was no relation to the relative magnitude of FV drop during the compression. CONCLUSIONS Brief (> 5 seconds) carotid artery compression provides an index of cerebral autoregulation that is reproducible and is affected by CO2 tension in a fashion similar to autoregulatory indices derived from a standard leg-cuff test. The simplicity of the method provides a potentially useful addition to other noninvasive autoregulation tests for clinical assessments, particularly when repeated measurements are required.
Collapse
Affiliation(s)
- P Smielewski
- MRC Cambridge Centre for Brain Repair and Academic Neurosurgical Unit, Addenbrooke's Hospital, University of Cambridge, UK
| | | | | | | | | | | |
Collapse
|
42
|
Mélot C, Berré J, Moraine JJ, Kahn RJ. Estimation of cerebral blood flow at bedside by continuous jugular thermodilution. J Cereb Blood Flow Metab 1996; 16:1263-70. [PMID: 8898700 DOI: 10.1097/00004647-199611000-00022] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The Kety-Schmidt technique can be regarded as the reference method for the measurement of cerebral blood flow (CBF). However, the method is somewhat cumbersome for routine use in the intensive care unit (ICU) at the beside. The continuous thermodilution technique developed many years ago for the measurement of coronary sinus blood flow can be applied for the measurement of jugular blood flow (JBF). However, the measurement of JBF by thermodilution has never been validated using the Kety-Schmidt reference method. We first validate the continuous thermodilution in vitro by comparison with a volumetric flow. The thermodilution method is accurate for flows between 50 and 900 ml min-1 with a mean difference volumetric-thermodilution flow of -1 +/- 18 ml min-1 (mean +/- SD), and precise with a coefficient of variability ranging between 1.21% and 2.50%. In vivo accuracy was assessed by comparing in 15 comatose patients CBF measured using the Kety-Schmidt (CBFKS) method and estimated from JBF measured by thermodilution (CBFTH) at four levels of arterial PaCO2 (25, 30, 35, and 40 mm Hg). The mean difference CBFKS-CBFTH is -0.9 +/- 3.6 ml min-1 100 g-1. In vivo precision of the method was good, with a coefficient of variability of 4.1% in mean. We conclude that jugular continuous thermodilution technique is a reliable method for estimating CBF at the bedside. This technique allows repeated measurements jugular bulb blood sampling for brain metabolic studies.
Collapse
Affiliation(s)
- C Mélot
- Department of Intensive Care, Erasme University Hospital, Brussels, Belgium
| | | | | | | |
Collapse
|
43
|
Nichols JS, Beel JA, Munro LG. Detection of impaired cerebral autoregulation using spectral analysis of intracranial pressure waves. J Neurotrauma 1996; 13:439-56. [PMID: 8880608 DOI: 10.1089/neu.1996.13.439] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Successful resuscitation following severe traumatic brain injury (TBI) requires rapid evaluation of intracranial pressure (ICP), cerebrovascular reactivity (autoregulation), and cerebral metabolism. During impaired autoregulation, inadequate cerebral blood flow (CBF) can lead to ischemia while excessive CBF can result in elevated ICP. Without information regarding the state of autoregulation, treatment of either situation may ameliorate one problem but exacerbate the other. It has been hypothesized that fast Fourier transform (FFT) analysis of arterial blood pressure (BP) and ICP waves can differentiate states of intact and impaired autoregulation. BP and ICP waves were recorded in canines before and after ischemic injury during arterial normotension, hypertension, and hypotension induced with dopamine or nitroprusside infusion. Transfer functions (TFn) were calculated from FFT spectra as ratios of ICP and BP harmonic peak amplitudes to distinguish states of vasoreactivity. During normotension and hypertension, autoregulation was intact and TF1 averaged 0.05. During hypotension, TF1 averaged 0.22 (8 x baseline, p < 0.010). During impaired autoregulation following ischemic injury, TF1 averaged 0.50 (18 x baseline, p < 0.010; 2 x nitroprusside levels, p < 0.01). This large difference in TF relative to baseline extended over a large range of BP (60 < BP < 180 mm Hg). Based on these data and previous results, it was estimated that TF can differentiate impaired autoregulation from effects solely related to elevated ICP or active vasodilation for ICP < 30-40 mm Hg. This suggests that for specific, but widely applicable physiologic conditions, spectral analysis can identify states of impaired autoregulation and, as an adjunct to traditional monitoring techniques, aid in acute resuscitation and prevention of secondary injury in TBI.
Collapse
Affiliation(s)
- J S Nichols
- Division of Neurological Surgery, Provenant Saint Anthony Central Hospital, Denver, Colorado, USA
| | | | | |
Collapse
|
44
|
Nilsson F, Nilsson T, Edvinsson L, Rosén I, Björkman S, Messeter K, Nordström CH. Sumatriptan-induced cerebral vasoconstriction as treatment of experimental intracranial hypertension. Acta Anaesthesiol Scand 1996; 40:612-20. [PMID: 8792894 DOI: 10.1111/j.1399-6576.1996.tb04497.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Increased intracranial pressure (ICP) is a major cause of mortality in severe head injuries and pharmacologically induced cerebral vasoconstriction has been suggested as a possible treatment. In the present study a porcine model of increased ICP was utilized to study the changes in cerebral haemodynamics and energy metabolism induced by a selective 5-hydroxytryptamine1 agonist (sumatriptan). METHODS ICP was raised by inflation of two balloons covering both parieto-occipital regions extradurally. The animals were randomized into four groups receiving sumatriptan. 0.01 mg.kg-1 (A), 0.03 mg.kg-1 (B), 0.1 mg.kg-1 (C), and 0.5 mg.kg-1 (D) intravenously over 10 min. Measurements of cerebral blood flow (CBF), arterio-venous oxygen content difference (CavO2), and jugular venous pH (vpH) were performed 5, 20, 40, 60, and 75 min after start of the infusion. ICP, mean arterial pressure, and EEG were recorded continuously. Direct effects of sumatriptan were also compared in cortical arteries and veins in vitro. RESULTS Significant decreases in ICP were obtained in groups A, B, and C while group D exhibited a progressive increase in ICP. Significant reductions in CBF, increase in CavO2, and slowing of EEG were observed in groups B, C, and D. Sumatriptan caused moderate constriction of the arteries and a more pronounced dilatation of veins in vitro. CONCLUSION The results indicate that a low dose of sumatriptan has the potential to reduce a raised ICP. High doses of sumatriptan cause a further increase of ICP possibly by dilatation of intracerebral veins.
Collapse
Affiliation(s)
- F Nilsson
- Department of Anaesthesia and Intensive Care, Malmö University Hospital, Sweden
| | | | | | | | | | | | | |
Collapse
|
45
|
Dahl B, Bergholt B, Cold GE, Astrup J, Mosdal B, Jensen K, Kjaersgaard JO. CO(2) and indomethacin vasoreactivity in patients with head injury. Acta Neurochir (Wien) 1996; 138:265-73. [PMID: 8861694 DOI: 10.1007/bf01411736] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The purpose of this study was to compare the effect of hyperventilation and indomethacin on cerebral circulation, metabolism and pressures in patients with acute severe head injury in order to see if indomethacin may act supplementary to hyperventilation. Fourteen severely head injured patients entered the study. Intracranial pressure (ICP), mean arterial blood pressure (MABP) and cerebral perfusion pressure (CPP) were monitored continuously. Within the first four days after the trauma the CO(2) and indomethacin vasoreactivities were studied by measurements of cerebral blood flow (CBF) (Cerebrograph 10a, intravenous (133)Xe technique) and arterio-venous difference of oxygen (AVdO(2)). Ischaemia was evaluated from changes in CBF, saturation of oxygen in the jugular bulb (SvjO(2)), lactate and lactate/oxygen index (LOI). Data are presented as medians and ranges, results are significant unless otherwise indicated. Before intervention ICP was well controlled ,(14.8 (9-24) mmHg) and basic CBF level was 39.1 (21.6-75.0) ml/100 g/min). The arterio-venous oxygen differences were generally decreased (AVdO(2) = 4.3 (1.8-8.1) ml/100 ml) indicating moderate luxury perfusion. Levels of CMRO(2) were decreased (1.54 (0.7-3.2) ml/100 g/min) as well. During hyperventilation (delta PaCO(2)=0.88 (0.62-1.55) kPa) CBF decreased with 11.8 (-33.4-29.7) %/kPa and ICP decreased with 3.8 (0-10) mmHg. AVdO(2) increased 34.0 (4.0-139.2) %/kPa, MABP was unchanged, CMRO(2) and CPP increased (delta CPP = 3.9 (-10-20) mmHg). AVD (lactate) and LOI were unchanged. No correlations between CBF responses to hypocapnia and outcomes were observed. An i.v. bolus dose of indomethacin (30 mg) decreased CBF 14.7 (-16.7-57.4)% and ICP decreased 4.3 (-1-17) mmHg. AVdO(2) increased 27.8 (-40.0-66.7)%, MABP (delta MABP = 4.9 (-2-21) mmHg) and CPP (delta CPP = 8.7 (3-29) mmHg) increased while CMRO2 was unchanged. No changes in AVd (lactate) and LOI indicating cerebral ischaemia were found. Compared to hyperventilation (changes per 1 kPa, at PaCO(2) level = 4.05 kPa) the changes in MABP, CPP and CBF were significantly greater after indomethacin, while the changes in AVdO(2), ICP, SvjO(2) and LOI were of the same order of magnitude. No correlation between relative reactivities to indomethacin and CO(2), evaluated from changes in CBF and AVdO(2), or between the decrease in ICP after the two procedures were found. Thus, some patients reacted to indomethacin but not to hyperventilation, and vice versa. These results suggest that indomethacin and hyperventilation might act independently, or in a complementary fashion in the treatment of patients with severe head injury.
Collapse
Affiliation(s)
- B Dahl
- Department of Neuroanaesthesia, Arhus University Hospital, Arhus, Denmark
| | | | | | | | | | | | | |
Collapse
|
46
|
Cruz J. Cerebrovascular reactivity. J Neurosurg 1996; 84:306-8. [PMID: 8592244 DOI: 10.3171/jns.1996.84.2.0306a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
|
47
|
Lillywhite N, Matta B. Loss of cerebral pressure autoregulation and vasoreactivity to carbon dioxide after cerebral hypoxia. Anaesth Intensive Care 1996; 24:91-3. [PMID: 8669662 DOI: 10.1177/0310057x9602400116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- N Lillywhite
- Department of Anaesthesia, Ipswich Hospital, Suffolk, United Kingdom
| | | |
Collapse
|
48
|
Smielewski P, Kirkpatrick P, Minhas P, Pickard JD, Czosnyka M. Can cerebrovascular reactivity be measured with near-infrared spectroscopy? Stroke 1995; 26:2285-92. [PMID: 7491652 DOI: 10.1161/01.str.26.12.2285] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND AND PURPOSE We used near-infrared spectroscopy (NIRS) to monitor the cerebral oxygenation changes during CO2 reactivity tests. METHODS Fifty healthy volunteers were examined (age range, 19 to 68 years). The monitored parameters were as follows: transcranial Doppler (TCD) time-averaged middle cerebral artery flow velocity end-tidal CO2 (EtCO2); change in concentration of cerebral oxyhemoglobin (HbO2), deoxyhemoglobin (Hb), and total hemoglobin; mean arterial blood pressure; peripheral arterial oxygen saturation (SaO2); and extracranial tissue perfusion with the use of cutaneous laser-Doppler flowmetry. The examination protocol included both hypercapnia and hypocapnia. The cerebrovascular reactivity indexes were calculated as follows: TCD, relative change in flow velocity per 1 kPa increase in EtCO2; NIRS, absolute change in HbO2, Hb, and total hemoglobin concentration (micromoles per liter) per 1 kPa increase in EtCO2. RESULTS Mean middle cerebral artery flow velocity was found to be 58 cm/s at a mean baseline EtCO2 of 4.7 kPa. Mean cerebrovascular reactivities were as follows: TCD, 24%/kPa (SEM, 1.1); HbO2, 2.06 mumol/L per kilopascal (SEM, 0.08); Hb, -0.63 mumol/L per kilopascal (SEM, 0.09); and total hemoglobin concentration, 1.44 mumol/L per kilopascal (SEM, 0.1). Statistical analysis revealed significant correlation between reactivities calculated with the use of NIRS and TCD (P < .001). Although some fluctuations were observed in SaO2 and laser-Doppler flux, they were not correlated with either EtCO2 or NIRS. CONCLUSIONS NIRS signal changes in HbO2, Hb, and total hemoglobin concentration are very sensitive to alterations in EtCO2, which are largely independent of extracranial tissue perfusion. NIRS may be developed as an alternative method for testing cerebrovascular reactivity and may be of particular clinical importance when the ultrasound window is poor.
Collapse
Affiliation(s)
- P Smielewski
- Medical Research Council Cambridge Centre for Brain Repair and Academic Neurosurgical Unit, Addenbrooke's Hospital, University of Cambridge, UK
| | | | | | | | | |
Collapse
|
49
|
Nilsson F, Messeter K, Grände PO, Rosén I, Ryding E, Nordström CH. Effects of dihydroergotamine on cerebral circulation during experimental intracranial hypertension. Acta Anaesthesiol Scand 1995; 39:916-21. [PMID: 8848892 DOI: 10.1111/j.1399-6576.1995.tb04198.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Different cerebral vasoconstrictors have recently been suggested for the treatment of raised intracranial pressure (ICP), in patients with severe traumatic brain lesions. Such treatment may be associated with severe side effects. A porcine model simulating an intracranial mass lesion was utilized to examine the haemodynamic cerebral effects of dihydroergotamine (DHE), a recently introduced pharmacological treatment for raised intracranial pressure. Intracranial hypertension was induced by inflation of two tonometric gastric balloons placed extradurally covering the parieto-occipital region bilaterally. The animals were randomized into one group with six animals receiving 1.0 mg of DHE i.v. followed by a continuous infusion of 0.2 mg/h (high dose) and another group of six animals receiving 0.15 mg i.v. followed by 0.03 mg/h (low dose). Measurements of cerebral blood flow (CBF) and arterio-venous difference in oxygen content (CaVO2) were performed by 5, 20 and 60 min after the DHE infusion. Intracranial pressure (ICP), mean arterial blood pressure (MAP) and cerebral electrical activity (EEG) were recorded continuously. In both groups infusion of DHE caused a lasting decrease in ICP probably achieved mainly by a decrease in cerebral blood volume due to constriction of both arterial and venous capacitance vessels. In the group treated with high-dose DHE, but not in that given low-dose DHE, a progressive increase in CaVO2, a fall in jugular venous pH and an increase in EEG delta activity were observed indicating cerebral hypoxia. The study supports the view that DHE may be a valuable tool in the pharmacological treatment of increased ICP in traumatic brain lesions but underscores the importance of a proper dosage.
Collapse
Affiliation(s)
- F Nilsson
- Department of Anaesthesia and Intensive Care, Malmö General Hospital, Lund University, Sweden
| | | | | | | | | | | |
Collapse
|
50
|
Levy B, Bollaert PE, Nace L, Larcan A. Intracranial hypertension and adult respiratory distress syndrome: usefulness of tracheal gas insufflation. THE JOURNAL OF TRAUMA 1995; 39:799-801. [PMID: 7473982 DOI: 10.1097/00005373-199510000-00039] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The management of increased intracranial pressure (ICP) in patients with an associated acute lung injury is difficult. High levels of PaCO2 as tolerated for permissive hypercapnia are deleterious for cerebral circulation. In such circumstances, tracheal gas insufflation (TGI), which was recently proposed to reduce PaCO2, may be of benefit. We report the cases of two patients with severe adult respiratory distress syndrome and head trauma complicated with elevated ICP. The introduction of TGI decreased PaCO2 by 17 and 26%, decreased ICP, and increased calculated cerebral perfusion pressure. We conclude that TGI could be added to a pressure-targeted strategy of ventilatory management when severe adult respiratory distress syndrome was associated to an intracranial hypertension.
Collapse
Affiliation(s)
- B Levy
- Polyvalent Intensive Care Unit, Central Hospital, Nancy, France
| | | | | | | |
Collapse
|