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Jufar AH, Lankadeva YR, May CN, Cochrane AD, Marino B, Bellomo R, Evans RG. Renal and Cerebral Hypoxia and Inflammation During Cardiopulmonary Bypass. Compr Physiol 2021; 12:2799-2834. [PMID: 34964119 DOI: 10.1002/cphy.c210019] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cardiac surgery-associated acute kidney injury and brain injury remain common despite ongoing efforts to improve both the equipment and procedures deployed during cardiopulmonary bypass (CPB). The pathophysiology of injury of the kidney and brain during CPB is not completely understood. Nevertheless, renal (particularly in the medulla) and cerebral hypoxia and inflammation likely play critical roles. Multiple practical factors, including depth and mode of anesthesia, hemodilution, pump flow, and arterial pressure can influence oxygenation of the brain and kidney during CPB. Critically, these factors may have differential effects on these two vital organs. Systemic inflammatory pathways are activated during CPB through activation of the complement system, coagulation pathways, leukocytes, and the release of inflammatory cytokines. Local inflammation in the brain and kidney may be aggravated by ischemia (and thus hypoxia) and reperfusion (and thus oxidative stress) and activation of resident and infiltrating inflammatory cells. Various strategies, including manipulating perfusion conditions and administration of pharmacotherapies, could potentially be deployed to avoid or attenuate hypoxia and inflammation during CPB. Regarding manipulating perfusion conditions, based on experimental and clinical data, increasing standard pump flow and arterial pressure during CPB appears to offer the best hope to avoid hypoxia and injury, at least in the kidney. Pharmacological approaches, including use of anti-inflammatory agents such as dexmedetomidine and erythropoietin, have shown promise in preclinical models but have not been adequately tested in human trials. However, evidence for beneficial effects of corticosteroids on renal and neurological outcomes is lacking. © 2021 American Physiological Society. Compr Physiol 11:1-36, 2021.
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Affiliation(s)
- Alemayehu H Jufar
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, Australia.,Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Yugeesh R Lankadeva
- Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia.,Department of Critical Care, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Victoria, Australia
| | - Clive N May
- Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia.,Department of Critical Care, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Victoria, Australia
| | - Andrew D Cochrane
- Department of Cardiothoracic Surgery, Monash Health and Department of Surgery (School of Clinical Sciences at Monash Health), Monash University, Melbourne, Victoria, Australia
| | - Bruno Marino
- Cellsaving and Perfusion Resources, Melbourne, Victoria, Australia
| | - Rinaldo Bellomo
- Department of Critical Care, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Victoria, Australia.,Department of Intensive Care, Austin Health, Heidelberg, Victoria, Australia
| | - Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, Australia.,Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
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2
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Avoiding use of total circulatory arrest in the practice of congenital heart surgery. Indian J Thorac Cardiovasc Surg 2020; 37:174-182. [PMID: 33603289 DOI: 10.1007/s12055-020-00955-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 03/21/2020] [Accepted: 04/22/2020] [Indexed: 11/27/2022] Open
Abstract
Deep hypothermic circulatory arrest (DHCA) technique has been an important armamentarium in the correction of congenital heart diseases. There have been many controversies and concerns associated with DHCA, particularly neurological damage. Selective ante grade cerebral perfusion (SACP) was introduced as an adjunct to DHCA with the objective of limiting the neurologic injury during aortic arch repairs. Over the past two decades, various aspects of cardiopulmonary bypass and DHCA have been studied and modified such as optimisation of flows, anti-inflammatory interventions, haematocrit, and temperature to improve neurologic outcomes. With the changes in practice of DHCA, outcomes have significantly improved but SACP intuitively appears attractive to offer better neuroprotection. The strategy of conduct of SACP is evolving and needs to be standardised for comparing outcomes. In this review we have discussed the various physiological and technical factors involved in conduct of SACP in paediatric cardiac surgery and outcomes with SACP.
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3
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Bojan M, Gioia E, Di Corte F, Berkia I, Tourneur T, Tourneur L, De Somer F. Lower limit of adequate oxygen delivery for the maintenance of aerobic metabolism during cardiopulmonary bypass in neonates. Br J Anaesth 2020; 124:395-402. [PMID: 32035629 DOI: 10.1016/j.bja.2019.12.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 11/16/2019] [Accepted: 12/09/2019] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The objective of cardiopulmonary bypass (CPB) is to maintain an adequate balance between oxygen delivery (Ḋo2) and consumption. The critical Ḋo2 is that at which consumption becomes supply dependent. This study aimed to identify the critical Ḋo2 in neonates, who have higher metabolic rates than adults. METHODS In a retrospective cohort of neonates, Ḋo2 was calculated from CPB parameters recorded during aortic cross-clamping. High lactate concentration measured after aortic unclamping (lactOFF) was used to identify anaerobic metabolism. Data were analysed using mixed linear and proportional odds regression models. The relationship between Ḋo2 and temperature was analysed in a subgroup of patients with lactOFF <2.5 mM, thought to have had balanced oxygen delivery and consumption. The estimated regression coefficient was further used to adjust hypothetical Ḋo2 thresholds, and Ḋo2 excursions below the threshold were quantified as magnitude-durations. The lowest threshold that provided magnitude-durations and linked with an increase in lactOFF was used as the lowest suitable (critical) Ḋo2 at 37°C. RESULTS Overall, 22 896 time points were analysed in 180 neonates. In 40 patients with lactOFF <2.5 mM, Ḋo2 varied by 22.87 (0.70) ml min-1 m-2 °C-1. When varying the Ḋo2 threshold between 340 and 380 ml min-1 m-2, excursions below the threshold were linked with incremental lactOFF. A 100 ml m-2 excursion below the 340 ml min-1 m-2Ḋo2 threshold increased the risk of a 1 mM increment in lactOFF by 22% (odds ratio: 1.22; 95% confidence interval: 1.02-1.45). CONCLUSIONS It was found that 340 ml min-1 m-2 is likely to represent the lowest suitable Ḋo2 required in neonates to maintain aerobic metabolism during normothermic CPB.
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Affiliation(s)
- Mirela Bojan
- Department of Anaesthesiology, Congenital Cardiac Unit, Marie Lannelongue Hospital, Le Plessis-Robinson, France.
| | - Enza Gioia
- Department of Anaesthesiology and Critical Care, Necker-Enfants Malades University Hospital; Paris, France
| | - Federica Di Corte
- Department of Anaesthesiology and Critical Care, Necker-Enfants Malades University Hospital; Paris, France
| | - Ilham Berkia
- Department of Paediatric Cardiac Surgery, Perfusion Unit, Necker-Enfants Malades University Hospital, Paris, France
| | - Tiffany Tourneur
- Department of Paediatric Cardiac Surgery, Perfusion Unit, Necker-Enfants Malades University Hospital, Paris, France
| | - Laurent Tourneur
- Department of Paediatric Cardiac Surgery, Perfusion Unit, Necker-Enfants Malades University Hospital, Paris, France
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4
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Stegeman R, Lamur KD, van den Hoogen A, Breur JMPJ, Groenendaal F, Jansen NJG, Benders MJNL. Neuroprotective Drugs in Infants With Severe Congenital Heart Disease: A Systematic Review. Front Neurol 2018; 9:521. [PMID: 30018590 PMCID: PMC6037764 DOI: 10.3389/fneur.2018.00521] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 06/13/2018] [Indexed: 12/20/2022] Open
Abstract
Background: Perinatal and perioperative brain injury is a fundamental problem in infants with severe congenital heart disease undergoing neonatal cardiac surgery with cardiopulmonary bypass. An impaired neuromotor and neurocognitive development is encountered and associated with a reduction in quality of life. New neuroprotective drugs during surgery are described to reduce brain injury and improve neurodevelopmental outcome. Therefore, our aim was to provide a systematic review and best-evidence synthesis on the effects of neuroprotective drugs on brain injury and neurodevelopmental outcome in congenital heart disease infants requiring cardiac surgery with cardiopulmonary bypass. Methods: A systematic search was performed in PubMed, Embase and the Cochrane Library (PRISMA statement). Search terms were “infants,” “congenital heart disease,” “cardiac surgery,” “cardiopulmonary bypass,” and “neuroprotective drug.” Data describing the effects on brain injury and neurodevelopmental outcome were extracted. Study quality was assessed with the Cochrane Risk of Bias Tool. Two reviewers independently screened sources, extracted data and scored bias. Disagreements were resolved by involving a third researcher. Results: The search identified 293 studies of which 6 were included. In total 527 patients with various congenital heart diseases participated with an average of 88 infants (13–318) per study. Allopurinol, sodium nitroprusside, erythropoietin, ketamine, dextromethorphan and phentolamine were administered around cardiac surgery with cardiopulmonary bypass. Allopurinol showed less seizures, coma, death and cardiac events in hypoplastic left heart syndrome (HLHS) infants (OR: 0.44; 95%-CI:0.21–0.91). Sodium nitroprusside resulted in lower post cardiopulmonary bypass levels of S100ß in infants with transposition of the great arteries after 24 (p < 0.01) and 48 (p = 0.04) h of treatment. Erytropoietin, ketamine and dextromethorphan showed no neuroprotective effects. Phentolamine led to higher S100ß-levels and cerebrovascular resistance after rewarming and at the end of surgery (both p < 0.01). Risk of bias varied between studies, including low (sodium nitroprusside, phentolamine), moderate (ketamine, dextromethorphan), and high (erytropoietin, allopurinol) quality. Conclusions: Allopurinol seems promising for future trials in congenital heart disease infants to reduce brain injury given the early neuroprotective effects in hypoplastic left heart syndrome infants. Larger well-designed trials are needed to assess the neuroprotective effects of sodium nitroprusside, erytropoietin, ketamine and dextromethorphan. Future neuroprotective studies in congenital heart disease infants should not only focus on the perioperative period, however also on the perinatal period, since significant brain injury already exists before surgery.
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Affiliation(s)
- Raymond Stegeman
- Department of Neonatology, University Medical Center Utrecht, Utrecht University, Wilhelmina Children's Hospital, Utrecht, Netherlands.,Department of Pediatric Cardiology, University Medical Center Utrecht, Utrecht University, Wilhelmina Children's Hospital, Utrecht, Netherlands.,Department of Pediatric Intensive Care, University Medical Center Utrecht, Utrecht University, Wilhelmina Children's Hospital, Utrecht, Netherlands
| | - Kaya D Lamur
- Department of Neonatology, University Medical Center Utrecht, Utrecht University, Wilhelmina Children's Hospital, Utrecht, Netherlands.,Department of Pediatric Cardiology, University Medical Center Utrecht, Utrecht University, Wilhelmina Children's Hospital, Utrecht, Netherlands.,Department of Pediatric Intensive Care, University Medical Center Utrecht, Utrecht University, Wilhelmina Children's Hospital, Utrecht, Netherlands
| | - Agnes van den Hoogen
- Department of Neonatology, University Medical Center Utrecht, Utrecht University, Wilhelmina Children's Hospital, Utrecht, Netherlands
| | - Johannes M P J Breur
- Department of Pediatric Cardiology, University Medical Center Utrecht, Utrecht University, Wilhelmina Children's Hospital, Utrecht, Netherlands
| | - Floris Groenendaal
- Department of Neonatology, University Medical Center Utrecht, Utrecht University, Wilhelmina Children's Hospital, Utrecht, Netherlands
| | - Nicolaas J G Jansen
- Department of Pediatric Intensive Care, University Medical Center Utrecht, Utrecht University, Wilhelmina Children's Hospital, Utrecht, Netherlands
| | - Manon J N L Benders
- Department of Neonatology, University Medical Center Utrecht, Utrecht University, Wilhelmina Children's Hospital, Utrecht, Netherlands
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5
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McLennan D, Caputo M, Taliotis D. Severe Aortic Stenosis and Severe Coarctation of the Aorta: A Hybrid Approach to Treatment. Front Surg 2017; 4:16. [PMID: 28367436 PMCID: PMC5355438 DOI: 10.3389/fsurg.2017.00016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/02/2017] [Indexed: 11/13/2022] Open
Abstract
Hybrid surgery is becoming more popular in the treatment of children with congenital heart disease, particularly small infants and neonates. We report a case of a patient with aortic stenosis (AS) and coarctation of the aorta (CoA). Case: a 1-month-old baby presented with severe AS and CoA. The decision was made to perform a hybrid surgical procedure. The patient underwent a lateral thoracotomy for repair of the CoA and carotid cutdown for aortic balloon valvuloplasty (AoVP).
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Affiliation(s)
- Daniel McLennan
- Department of Cardiology, Bristol Royal Hospital for Children, University of Bristol , Bristol , UK
| | - Massimo Caputo
- Department of Cardiac Surgery, Bristol Heart Institute, University of Bristol , Bristol , UK
| | - Demetris Taliotis
- Department of Cardiology, Bristol Royal Hospital for Children, University of Bristol , Bristol , UK
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6
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Abstract
Children and particularly neonates present unique challenges during CPB. Patient age, size, underlying anatomy and surgical strategy influence the perfusion techniques and the construction of the CPB circuit. The normal changes in physiology in the first weeks of life impact upon surgical technique and outcome of repair. Limited surgical access necessitates alternative cannulation strategies. Deep hypothermia, low flow CPB and circulatory arrest are frequently used. An understanding of the related pathophysiology is therefore required to make the correct choices and to optimise patient outcome.
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Affiliation(s)
- T J Jones
- Birmingham Children's Hospital, Steelhouse Lane, Birmingham, UK.
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7
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Hirsch JC, Jacobs ML, Andropoulos D, Austin EH, Jacobs JP, Licht DJ, Pigula F, Tweddell JS, Gaynor JW. Protecting the infant brain during cardiac surgery: a systematic review. Ann Thorac Surg 2012; 94:1365-73; discussion 1373. [PMID: 23006704 DOI: 10.1016/j.athoracsur.2012.05.135] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 05/15/2012] [Accepted: 05/25/2012] [Indexed: 11/26/2022]
Abstract
Prevention of brain injury during congenital heart surgery has focused on intraoperative and perioperative neuroprotection and neuromonitoring. Many strategies have been adopted as "standard of care." However, the strength of evidence for these practices and the relationship to long-term outcomes are unknown. We performed a systematic review (January 1, 1990 to July 30, 2010) of neuromonitoring and neuroprotection strategies during cardiopulmonary bypass (CPB) in infants of age 1 year or less. Papers were graded individually and as thematic groups, assigning evidence-based medicine and American College of Cardiology/American Heart Association (ACC/AHA) level of evidence grades. Consensus scores were determined by adjudication. Literature search identified 527 manuscripts; 162 met inclusion criteria. Study designs were prospective observational cohort (53.7%), case-control (21.6%), randomized clinical trial (13%), and retrospective observational cohort (9.9%). Median sample size was 43 (range 3 to 2,481). Primary outcome was evidence of structural brain injury or functional disability (neuroimaging, electroencephalogram, formal neurologic examination, or neurodevelopmental testing) in 43%. Follow-up information was reported in only 29%. The most frequent level of evidence was evidence-based medicine level 4 (33.3%) or ACC/AHA class IIB: level B (42%). The only intervention with sufficient evidence to recommend "the procedure or treatment should be performed" was avoidance of extreme hemodilution during CPB. Data supporting use of current neuromonitoring and neuroprotective techniques are limited. The level of evidence is insufficient to support effectiveness of most of these strategies. Well-designed studies with correlation to clinical outcomes and long-term follow-up are needed to develop guidelines for neuromonitoring and neuroprotection during CPB in infants.
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Affiliation(s)
- Jennifer C Hirsch
- Department of Cardiac Surgery, University of Michigan Medical Center, Mott Children's Hospital, Ann Arbor, Michigan 48109-4204, USA.
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8
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Amir G, Ramamoorthy C, Riemer RK, Hanley FL, Reddy VM. Deep brain hyperthermia while rewarming from hypothermic circulatory arrest. J Card Surg 2010; 24:606-10. [PMID: 19740304 DOI: 10.1111/j.1540-8191.2009.00883.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Neurologic injury is a feared and serious long-term complication of cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA). Postoperative hyperthermia was found to enhance postischemic neurologic injury. The use of core temperature as the reference point through CPB assumes parallel changes in brain temperature. We tested the hypothesis that regional and deep brain temperature (DBT) differ during cooling, DHCA, and rewarming. METHODS Neonatal piglets (n = 9) were subject to CPB and cooled to rectal temperature (RT) of 18 degrees C, 30 minutes of DHCA were initiated, and subsequently the piglets were rewarmed to RT of 36.5 degrees C and weaned from CPB. Temperature probes were inserted into the DBT targeting the caudate and thalamic nuclei, their position confirmed by pathology. Superficial brain temperature was measured by a temperature probe inserted extradurally. RT, nasopharyngeal (NPT), and tympanic (TT) temperatures were recorded. RESULTS During cooling the deep brain cooled faster and to lower temperatures compared to RT and TT; NPT reflected DBT accurately. During rewarming DBT was significantly higher than RT and TT. By the end of rewarming the difference between the deep brain and the RT reached statistical significance (30 minutes: 35.1 +/- 0.7 vs. 32.3 +/- 0.7 p < 0.05, respectively, 40 minutes: 37.5 +/- 0.3 vs. 34.7 +/- 0.8 p < 0.05, respectively). CONCLUSION Deep brain hyperthermia routinely occurs during the last stages of rewarming following DHCA. DBT is accurately reflected by NPT and is directly correlated with inflow temperature. Therefore, during rewarming inflow temperatures should not exceed 36 degrees C and NPT should be closely monitored.
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Affiliation(s)
- Gabriel Amir
- Department of Cardiothoracic Surgery, Pediatric Division, Schneider Children's Medical Center of Israel, Rabin Medical Center, Petach Tikva, Israel.
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9
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Schlunt ML, Brauer SD. Anesthetic management for the pediatric patient undergoing deep hypothermic circulatory arrest. Semin Cardiothorac Vasc Anesth 2007; 11:16-22. [PMID: 17484170 DOI: 10.1177/1089253206297411] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Early definitive repair of complex congenital heart defects is now advocated. For the completion of many of these repairs, the use of deep hypothermic circulatory arrest (DHCA) is an absolute necessity. Unfortunately, there is undeniable neurologic morbidity, as well as other complications associated with DHCA. Anesthesiologists can aid in minimizing these unfortunate complications with the appropriate anesthetic management. Areas of current controversy in managing pediatric patients undergoing DHCA, which will be covered in this article, include cardiopulmonary bypass strategies (low-flow cardiopulmonary bypass versus DHCA), arterial blood gas management, hemodilution effects, glucose management, and the use of steroids, barbiturates, and antifibrinolytics. Every institution varies in their techniques, and there is always some new insight to be gained from discussion of these differences. At this time, anesthesiologists and surgeons alike are striving to gain further understanding of what truly occurs with the use of DHCA and in turn apply this clinically to provide better care for all pediatric patients undergoing this unique management.
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10
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Amir G, Ramamoorthy C, Riemer RK, Davis CR, Hanley FL, Reddy VM. Visual light spectroscopy reflects flow-related changes in brain oxygenation during regional low-flow perfusion and deep hypothermic circulatory arrest. J Thorac Cardiovasc Surg 2006; 132:1307-13. [PMID: 17140947 DOI: 10.1016/j.jtcvs.2006.04.056] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Revised: 03/30/2006] [Accepted: 04/04/2006] [Indexed: 10/23/2022]
Abstract
OBJECTIVES Regional low-flow perfusion has been used to minimize ischemic brain injury during complex heart surgery in children. However, optimal regional low-flow perfusion remains undetermined. Visible light spectroscopy is a reliable method for continuous determination of capillary oxygen saturation (SgvO2). We used visible light spectroscopy to follow deep and superficial brain SgvO2 during cardiopulmonary bypass, regional low-flow perfusion, and deep hypothermic circulatory arrest. METHODS Visible light spectroscopy probes were inserted into the superficial and deep brain of neonatal (3.9-4.5 kg) piglets, targeting the caudate and thalamic nuclei. The piglets were subjected to cardiopulmonary bypass and cooled to a rectal temperature of 18 degrees C using pH stat. Regional low-flow perfusion was initiated through the innominate artery at 18 degrees C, and pump flows were adjusted to 40, 30, 20, and 10 mL/kg/min for 10-minute intervals followed by 30 minutes of deep hypothermic circulatory arrest. Regional low-flow perfusion was reestablished, and flows were increased in a stepwise manner from 10 to 40 mL/kg/min. SgvO2 was continuously monitored. Carotid flow was measured using a flow probe, and cerebral blood flow (milliliters per kilogram body weight per minute) was calculated. RESULTS There were no significant differences between the deep and superficial brain tissue oxygenation during regional low flow brain perfusion before deep hypothermic circulatory arrest. However, after deep hypothermic circulatory arrest, the superficial brain SgvO2 was lower than the deep brain SgvO2 (24 +/- 12 vs 55.3 +/- 8, P = .05, at flows of 30 mL/kg/min, and 34.2 +/- 17 vs 62.5 + 8, P = .06, at a flow rate of 40 mL/kg/min). During regional low-flow perfusion, SgvO2 was maintained at flows of 30 to 40 mL/kg/min (cerebral blood flows of 15 to 21 mL/kg/min and 19 to 24 mL/kg/min, respectively), but was significantly lower at pump flows of 20 mL/kg/min (cerebral blood flow of 10 to 14 mL/kg/min) and 10 mL/kg/min (cerebral blood flow of 5 to 9 mL/kg/min) compared with the values obtained just before regional low-flow perfusion (pre-deep hypothermic circulatory arrest, 37 +/- 6 vs 65.5 +/- 4.4, P < .05, and 21.6 +/- 3.7 vs 65.5 +/- 4.4, P < .01, respectively; and post-deep hypothermic circulatory arrest, 32 +/- 4.5 vs 65.5 +/- 4.4, P < .05, and 16.6 +/- 4.7 vs 65.5 +/- 4.4, P < .01, respectively). CONCLUSIONS Regional low-flow perfusion at pump flows of 30 to 40 mL/kg/min with resulting cerebral blood flows of 14 to 24 mL/kg/min was adequate in maintaining both deep and superficial brain oxygenation. However, lower pump flows of 20 and 10 mL/kg/min, associated with cerebral blood flow of 9 to 14 mL/kg/min, resulted in significantly reduced SgvO2 values.
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Affiliation(s)
- Gabriel Amir
- Division of Pediatric Cardiac Surgery, LPCH, Stanford Medical Center, Stanford, Calif, USA.
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11
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Amir G, Ramamoorthy C, Riemer RK, Reddy VM, Hanley FL. Neonatal Brain Protection and Deep Hypothermic Circulatory Arrest: Pathophysiology of Ischemic Neuronal Injury and Protective Strategies. Ann Thorac Surg 2005; 80:1955-64. [PMID: 16242503 DOI: 10.1016/j.athoracsur.2004.12.040] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2004] [Revised: 12/20/2004] [Accepted: 12/28/2004] [Indexed: 11/15/2022]
Abstract
Deep hypothermic circulatory arrest (DHCA) has been used for the past 50 years in the surgical repair of complex congenital cardiac malformations and operations involving the aortic arch; it enables the surgeon to achieve precise anatomical reconstructions by creating a bloodless operative field. Nevertheless, DHCA has been associated with immediate and late neurodevelopmental morbidities. This review provides an overview of the pathophysiology of neonatal hypoxic brain injury after DHCA, focusing on cellular mechanisms of necrosis, apoptosis, and glutamate excitotoxicity. Techniques and strategies in neonatal brain protection include hypothermia, acid base blood gas management during cooling, and pharmacologic interventions such as the use of volatile anesthetics. Surgical techniques consist of intermittent cerebral perfusion during periods of circulatory arrest and continuous regional brain perfusion.
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Affiliation(s)
- Gabriel Amir
- Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California 94305, USA.
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12
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MacDonald MJ, Hanley FL, Reddy VM. Arch reconstruction without circulatory arrest: current clinical applications and results of therapy. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 2004; 5:95-103. [PMID: 11994869 DOI: 10.1053/pcsu.2002.31503] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Laboratory and clinical data have confirmed the deleterious effects of deep hypothermic circulatory arrest. Long-term data and rigorous neuropsychiatric data are currently sparse, but that which are available show adverse outcomes following circulatory arrest, and therefore support the use of continuous perfusion techniques. There are no available long-term data on continuous perfusion techniques with respect to neurologic outcomes, but using these techniques the incidence of postoperative seizures or other neurologic events is rare. Currently available bypass systems and microsurgical techniques have allowed continuous flow and regional perfusion to become practical alternatives. Several innovative techniques for avoiding circulatory arrest during neonatal aortic arch reconstruction for univentricular and biventricular hearts are described. It would appear prudent and desirable to provide continuous perfusion now that long-term survival after repair of even the most complex cardiac anomalies including single ventricle defects is commonplace.
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Affiliation(s)
- Malcolm J MacDonald
- Department of Cardiothoracic Surgery, Stanford University Medical Center, Stanford, CA, USA
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13
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Ito T. Effect of deep hypothermia on cerebral hemodynamics during selective cerebral perfusion with systemic circulatory arrest. THE JAPANESE JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY : OFFICIAL PUBLICATION OF THE JAPANESE ASSOCIATION FOR THORACIC SURGERY = NIHON KYOBU GEKA GAKKAI ZASSHI 2002; 50:109-15. [PMID: 11968717 DOI: 10.1007/bf02913471] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE We studied the effect of deep hypothermia on cerebral hemodynamics during selective cerebral perfusion with systemic circulatory arrest. METHODS Ten anesthesized pigs were placed on cardiopulmonary bypass and cooled to a rectal temperature of 22 degrees C (n = 5) or 15 degrees C (n = 5). During selective cerebral perfusion, the descending aorta was clamped and perfusion of the lower body was discontinued. As the pump flow was changed, we monitored the perfusion pressure, local cerebral blood flow, and local cerebral oxygenation using laser Doppler flowmetry and near-infrared spectroscopy. We also measured the free flow of the left internal thoracic artery during selective cerebral perfusion. RESULTS Perfusion pressure and local cerebral blood flow decreased as the pump flow decreased. Oxygenated and deoxygenated hemoglobin in cerebral tissue remained unchanged at a perfusion flow of 10 ml/kg/min, whereas oxygenated hemoglobin decreased and deoxygenated hemoglobin increased progressively and reciprocally as the pump flow decreased. The pump flow for maintaining perfusion pressure above 35 mmHg with stabilized local cerebral oxygenation was significantly higher at 15 degrees C than at 22 degrees C. The internal thoracic artery free flow was higher at 15 degrees C than at 22 degrees C. CONCLUSIONS Selective hypothermic cerebral perfusion with systemic circulatory arrest produces an extracranial shunt through the internal thoracic artery, especially under deep hypothermia. Our data suggests that selective cerebral perfusion during deep hypothermia is best managed by perfusion pressure control rather than by flow control.
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Affiliation(s)
- Tsutomu Ito
- Division of Cardiovascular Surgery, Department of Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, Tokyo 160-8582, Japan
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14
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Stephenson ER, Myers JL. Pediatric cardiopulmonary bypass. Ann Thorac Surg 2001; 72:2176-7. [PMID: 11789830 DOI: 10.1016/s0003-4975(01)02996-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- E R Stephenson
- Pediatric Cardiovascular Surgery, Penn State Children's Hospital, Penn State Hershey Medical Center, Hershey 17033, USA
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Jaggers J, Ungerleider RM. Cardiopulmonary bypass in infants and children. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 2001; 3:82-109. [PMID: 11486188 DOI: 10.1053/tc.2000.6033] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cardiopulmonary bypass (CPB) systems have evolved from futuristic visions of surgical pioneers to a safe and efficient tool in the therapy of treatment of cardiac disorders. There are many significant differences in the physiology between neonates and adult patients. There are currently very few congenital cardiac malformations that cannot be addressed effectively with surgical therapy. Yet, the necessity of CPB in the repair of these patients can still result in significant morbidity. A clearer understanding of the effects of CPB, hypothermia, and circulatory arrest is evolving and there is a considerable amount of research in these areas. It seems likely that modification of current CPB systems, minimization of exposure, and surgical techniques to avoid or limit the adverse effects may reduce mortality and morbidity in the future. The problems faced in these complex patients and procedures require that infant and neonatal cardiac surgery be performed in specialized centers with a multidisciplinary approach and specialized personnel. Future improvements in technology will likely result in improved long term outcome for children with congenital cardiac disease. Copyright 2000 by W.B. Saunders Company
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Affiliation(s)
- James Jaggers
- Division of Thoracic Surgery, Pediatric Cardiac Surgery, Duke University Medical Center, Durham, NC
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Sungurtekin H, Boston US, Cook DJ. Bypass flow, mean arterial pressure, and cerebral perfusion during cardiopulmonary bypass in dogs. J Cardiothorac Vasc Anesth 2000; 14:25-8. [PMID: 10698388 DOI: 10.1016/s1053-0770(00)90051-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To determine if normal cardiopulmonary bypass (CPB) pump flows maintain cerebral perfusion in the context of reduced mean arterial pressure at 33 degrees C. DESIGN A prospective investigation. SETTING Animal CPB research laboratory. PARTICIPANTS Seven dogs that underwent CPB. INTERVENTIONS Seven dogs underwent CPB at 33 degrees C using alpha-stat management and a halothane, fentanyl-midazolam anesthetic. Cerebral blood flow was measured using the sagittal sinus outflow technique. After control measurements at 70 mm Hg, cerebral physiologic values were determined under four conditions in random order: (1) mean arterial pressure of 60 mm Hg achieved by a reduction in pump flow, (2) mean arterial pressure of 60 mmHg determined by partial opening of a femoral arterial-to-venous reservoir shunt, (3) mean arterial pressure of 45 mm Hg by reduced pump flow, and (4) mean arterial pressure of 45 mm Hg by shunt. A 9F femoral arterial-to-venous reservoir shunt was controlled by a screw clamp. MEASUREMENTS AND MAIN RESULTS Except for the controlled variables of mean arterial pressure and bypass flow, physiologic determinants of cerebral blood flow (temperature, PaCO2 and hematocrit) did not differ under any of the CPB conditions. Pump flow per se was not a determinant of cerebral perfusion. Cerebral blood flow and cerebral oxygen delivery did not differ with changes in pump flow if mean arterial pressure did not differ. Cerebral blood flow depended on mean arterial pressure under all pump flow conditions, however. CONCLUSIONS Over the range of flows typical in adult CPB at 33 degrees C, pump flow does not have an effect on cerebral perfusion independent of its effect on mean arterial pressure. A targeted pump flow per se is not sufficient to maintain cerebral perfusion if mean arterial blood pressure is reduced.
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Affiliation(s)
- H Sungurtekin
- Department of Anesthesiology, Mayo Foundation and Mayo Clinic, Rochester, MN, USA
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Pigula FA, Nemoto EM, Griffith BP, Siewers RD. Regional low-flow perfusion provides cerebral circulatory support during neonatal aortic arch reconstruction. J Thorac Cardiovasc Surg 2000; 119:331-9. [PMID: 10649209 DOI: 10.1016/s0022-5223(00)70189-9] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE Because of concerns regarding the effects of deep hypothermia and circulatory arrest on the neonatal brain, we have developed a technique of regional low-flow perfusion that provides cerebral circulatory support during neonatal aortic arch reconstruction. METHODS We studied the effects of regional low-flow perfusion on cerebral oxygen saturation and blood volume as measured by near-infrared spectroscopy in 6 neonates who underwent aortic arch reconstruction and compared these effects with 6 children who underwent cardiac repair with deep hypothermia and circulatory arrest. RESULTS All the children survived with no observed neurologic sequelae. Near-infrared spectroscopy documented significant decreases in both cerebral blood volume and oxygen saturations in children who underwent repair with deep hypothermia and circulatory arrest as compared with children with regional low-flow perfusion. Reacquisition of baseline cerebral blood volume and cerebral oxygen saturations were accomplished with a regional low-flow perfusion rate of 20 mL x kg(-1) x min(-1). CONCLUSIONS Regional low-flow perfusion is a safe and simple bypass management technique that provides cerebral circulatory support during neonatal aortic arch reconstruction. The reduction of deep hypothermia and circulatory arrest time required may reduce the risk of cognitive and psychomotor deficits.
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Affiliation(s)
- F A Pigula
- Department of Pediatric Cardiothoracic Surgery, Children's Hospital of Pittsburgh, Pittsburgh, PA 15213, USA.
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Affiliation(s)
- M J Elliott
- Cardiothoracic Unit, The Great Ormond Street Hospital for Children NHS Trust, London, UK.
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Affiliation(s)
- L K Davies
- Department of Anesthesiology, University of Florida, Gainesville, USA
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Abstract
Neurological injury is a major and often debilitating complication of congenital heart disease and open-heart surgery. Paradoxically, the full impact of this complication has been underscored by the marked decrease in mortality and the rescue of infants with desperate and previously lethal heart conditions. Although recent focus has been on mechanisms of brain injury originating during open-heart surgery, this article also emphasizes the importance of mechanisms initiated or perpetuated during the preoperative and postoperative periods. In addition to the usually implicated mechanism of hypoxia-ischemia, recent genetic advances suggest an important role for genetic deletion syndromes. Inflammatory cascades have been implicated in the end-organ injury seen after cardiopulmonary bypass and might play a role in neurological dysfunction. These mechanisms are reviewed, with an emphasis on recent developments in our understanding of brain injury in this population.
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Affiliation(s)
- A J du Plessis
- Department of Neurology, Children's Hospital, Boston, MA 02115, USA
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Abstract
PURPOSE To analyze studies of neurological injury after open-heart surgery in infants and children and to discuss the effects of cardiopulmonary bypass, hypothermia and deep hypothermic circulatory arrest on cerebral blood flow, cerebral metabolism and brain temperature. SOURCE Articles were obtained from the databases, Current Science and Medline, from 1966 to present. Search terms include cardiopulmonary bypass (CPB), hypothermia, cerebral blood flow (CBF), cerebral metabolism and brain temperature. Information and abstracts obtained from meetings on the topic of brain and cardiac surgery helped complete the collection of information. PRINCIPAL FINDINGS In adults the incidence of neurological morbidity is between 7 to 87% with stroke in about 2-5%, whereas the incidence of neurological morbidity increases to 30% in infants and children undergoing cardiopulmonary bypass. Besides the medical condition of the patient, postoperative cerebral dysfunction and neuronal ischaemia associated with cardiac surgery in infants and small children are a combination of intraoperative factors. Deep hypothermic circulatory arrest impairs CBF and cerebral metabolism even after termination of CPB. Inadequate and/or non-homogenous cooling of the brain before circulatory arrest, as well as excessive rewarming of the brain during reperfusion are also major contributory factors. CONCLUSION Newer strategies, including the use of low-flow CPB, pulsatile CPB, pH-stat acid-base management and a cold reperfusion, are being explored to ensure better cerebral protection. Advances in monitoring technology and better understanding of the relationship of cerebral blood flow and metabolism during the different modalities of cardiopulmonary bypass management will help in the medical and anaesthetic development of strategies to improve neurological and developmental outcomes.
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Affiliation(s)
- H L Pua
- Department of Anaesthesia, Hospital for Sick Children, University of Toronto, Ontario, Canada
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Zimmerman AA, Burrows FA, Jonas RA, Hickey PR. The limits of detectable cerebral perfusion by transcranial Doppler sonography in neonates undergoing deep hypothermic low-flow cardiopulmonary bypass. J Thorac Cardiovasc Surg 1997; 114:594-600. [PMID: 9338645 DOI: 10.1016/s0022-5223(97)70049-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Neurologic morbidity including seizures, abnormal neurologic function, and delayed psychomotor development continue to be significant problems for some patients undergoing operations for congenital heart disease, particularly for those subjected to deep hypothermic circulatory arrest. The technique of low-flow cardiopulmonary bypass has been advocated to decrease the incidence of neurologic sequelae. Our study examined the limits of detectable blood flow in the middle cerebral artery during low-flow cardiopulmonary bypass in 28 neonates undergoing the arterial switch procedure. METHODS Cerebral blood flow velocity was measured noninvasively in the M1 segment of the middle cerebral artery with a 2 MHz range-gated pulsed-wave transcranial Doppler sonographic probe that was placed over the left temporal window. As part of the initiation of a planned period of deep hypothermic circulatory arrest, the cardiopulmonary bypass flow rate was decreased in stages to five low-flow rates (50, 40, 30, 20, and 10 ml/kg per minute). After a period of stabilization, cerebral blood flow velocities were recorded at each of the five low-flow rates and reported as a percentage of baseline. RESULTS All 28 neonates had detectable perfusion in the middle cerebral artery at flow rates of 30 ml/kg per minute or higher. At flows of 20 and 10 ml/kg per minute, one and eight, respectively, of the 28 neonates had no detectable perfusion in the middle cerebral artery. CONCLUSIONS Our data show that cerebral perfusion can be detected by transcranial Doppler sonography in the middle cerebral artery in some neonates at bypass pump flows as low as 10 ml/kg per minute. However, when transcranial Doppler sonography was used in our patient population, a minimum bypass flow rate of 30 ml/kg per minute was needed to detect cerebral perfusion in all neonates.
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Affiliation(s)
- A A Zimmerman
- Department of Anesthesia, Children's Hospital and Harvard Medical School, Boston, Mass, USA
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Chow G, Roberts IG, Edwards AD, Lloyd-Thomas A, Wade A, Elliott MJ, Kirkham FJ. The relation between pump flow rate and pulsatility on cerebral hemodynamics during pediatric cardiopulmonary bypass. J Thorac Cardiovasc Surg 1997; 114:568-77. [PMID: 9338642 DOI: 10.1016/s0022-5223(97)70046-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVES Neurologic impairment, at least partly ischemic in origin, has been reported in up to 25% of infants undergoing cardiopulmonary bypass, with or without circulatory arrest. Controversy continues about the effect of pump flow, pulsatile or nonpulsatile, on the brain and in particular on cerebral blood flow. This study examines the relationship between pump flow rate and cerebral hemodynamics during pulsatile and nonpulsatile cardiopulmonary bypass. METHOD Near-infrared spectroscopy was used to determine cerebral blood flow and cerebral blood volume (measured as concentration change) in a randomized crossover study. Pulsatile and nonpulsatile flow were used for six 5-minute intervals at each of three different pump flow rates (0.6, 1.2, and 2.4 L x m2 x min(-1)) in 40 patients, median age 2 months (range 2 weeks to 20 years 5 months). The relations between pulsatile flow, pump flow rate, cerebral blood flow, hemoglobin concentration change (cerebral blood volume), mean arterial pressure, arterial carbon dioxide tension, and hematocrit value were prospectively examined by means of multivariate analysis. RESULTS Cerebral blood flow decreased 36% per L x m(-2) x min(-1) decrease in pump flow rate and was associated with changes in mean arterial pressure but did not differ according to pulsatility. Change in hemoglobin concentration was unrelated to changes in pulsatility of pump flow. CONCLUSION Cerebral blood flow is related to pump flow rate. Pulsatile flow delivered with a Stöckert pump does not increase cerebral blood flow or alter hemoglobin concentration during cardiopulmonary bypass in children.
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Affiliation(s)
- G Chow
- Department of Neurosciences, Institute of Child Health (UCL)/Great Ormond Street Hospital for Children, London, United Kingdom
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du Plessis AJ. Cerebral hemodynamics and metabolism during infant cardiac surgery. Mechanisms of injury and strategies for protection. J Child Neurol 1997; 12:285-300. [PMID: 9378896 DOI: 10.1177/088307389701200501] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
There is an established link between congenital heart disease and acquired brain injury, which relates to the dependence of the nervous system on a consistent and responsive supply of oxygen and glucose. The advances in the field of infant cardiac surgery have presented new and different challenges to the arena of child neurology. This review provides an overview of the mechanisms of neurologic injury and cerebral hemodynamics and metabolism during cardiac surgery. This review discusses current and future strategies for the management of children with congenital heart disease.
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Affiliation(s)
- A J du Plessis
- Department of Neurology, Children's Hospital, Boston, MA 02115, USA
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Dexter F, Kern FH, Hindman BJ, Greeley WJ. The brain uses mostly dissolved oxygen during profoundly hypothermic cardiopulmonary bypass. Ann Thorac Surg 1997; 63:1725-9. [PMID: 9205174 DOI: 10.1016/s0003-4975(97)00297-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND During profoundly hypothermic cardiopulmonary bypass, cerebral venous oxygen saturation increases (eg, to 98% at 15 degrees C). We reanalyzed results of clinical studies to learn why. METHODS One hundred sixty-eight cerebral oxygen transport measurements were available from 96 infants and children undergoing profoundly hypothermic cardiopulmonary bypass during repair of congenital heart defects. RESULTS Dissolved oxygen accounted for 2% to 17% of arterial oxygen content, depending on the arterial oxygen partial pressure and hemoglobin concentration. The fraction of the cerebral metabolic rate for oxygen obtained from dissolved oxygen depended on pump flow, temperature, hemoglobin concentration, and arterial oxygen partial pressure (all p < 10(-3)). For "full-flow" cardiopulmonary bypass, temperatures less than 18 degrees C, and arterial oxygen partial pressure measurements more than 180 mm Hg, the mean +/- standard deviation of the fraction of cerebral metabolic rate for oxygen obtained from dissolved oxygen equaled 77% +/- 19%. CONCLUSIONS Dissolved oxygen satisfies most of the brain's oxygen requirements during profound hypothermic cardiopulmonary bypass. This result reflects four properties of profound hypothermic cardiopulmonary bypass: (1) increases in hemoglobin's oxygen affinity due to profound hypothermia (which impairs oxygen transfer from hemoglobin to cerebral tissue), (2) use of hemodilution, (3) use of high arterial oxygen partial pressure, and (4) low cerebral metabolic rate of oxygen.
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Affiliation(s)
- F Dexter
- Department of Anesthesia, University of Iowa, Iowa City 52242, USA
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Kurth CD, Steven JM, Nicolson SC, Jacobs ML. Cerebral oxygenation during cardiopulmonary bypass in children. J Thorac Cardiovasc Surg 1997; 113:71-8; discussion 78-9. [PMID: 9011704 DOI: 10.1016/s0022-5223(97)70401-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Previous work has found cerebral oxygen extraction to decrease during hypothermic cardiopulmonary bypass in children. To elucidate cardiopulmonary bypass factors controlling cerebral oxygen extraction, we examined the effect of perfusate temperature, pump flow rate, and hematocrit value on cerebral hemoglobin-oxygen saturation as measured by near infrared spectroscopy. METHODS Forty children less than 7 years of age scheduled for cardiac operations with continuous cardiopulmonary bypass were randomly assigned to warm bypass, hypothermic bypass, hypothermic low-flow bypass, or hypothermic low-hematocrit bypass. For warm bypass, arterial perfusate was 37 degrees C, hematocrit value 23%, and pump flow 150 ml/kg per minute. Hypothermic bypass differed from warm bypass only in initial perfusate temperature (22 degrees C); hypothermic low-flow bypass and low-hematocrit bypass differed from hypothermic bypass only in pump flow (75 ml/kg per minute) and hematocrit value (16%), respectively. Cerebral oxygen saturation was recorded before bypass (baseline), during bypass, and for 15 minutes after bypass had been discontinued. RESULTS In the warm bypass group, cerebral oxygen saturation remained at baseline levels during and after bypass. In the hypothermic bypass group, cerebral oxygen saturation increased 20% +/- 2% during bypass cooling (p < 0.001), returned to baseline during bypass rewarming, and remained at baseline after bypass. In the hypothermic low-flow and hypothermic low-hematocrit bypass groups, cerebral oxygen saturation remained at baseline levels during bypass but increased 6% +/- 2% (p = 0.05) and 10% +/- 2% (p < 0.03), respectively, after bypass was discontinued. CONCLUSIONS In children, cortical oxygen extraction is maintained during warm cardiopulmonary bypass at full flow and moderate hemodilution. Bypass cooling can decrease cortical oxygen extraction but requires a certain pump flow and hematocrit value to do so. Low-hematocrit hypothermic bypass and low-flow hypothermic bypass can also alter cortical oxygen extraction after discontinuation of cardiopulmonary bypass.
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Affiliation(s)
- C D Kurth
- Department of Anesthesia, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, 19104, USA
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Chapter 1 Hypothermia in relation to the acceptable limits of ischemia for bloodless surgery. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s1873-9792(96)80003-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Abstract
Temperature induces depression of cerebral perfusion and cerebral oxygen metabolism in particular, and this seems to explain why a reduced pump flow above a critical level is well tolerated during hypothermic cardiopulmonary bypass with apparent full metabolic recovery afterward. It only partly explains why a longer period of hypothermic circulatory arrest leads to a protracted recovery of cerebral perfusion and cerebral metabolism. This review suggests there is evidence that energy metabolism can easily be compromised during and after rewarming after hypothermic cardiopulmonary bypass with low flow and with circulatory arrest. Although data indicate that cerebral metabolism and cerebral energy state are better after low flow than after circulatory arrest, the risk of energy crises appears imminent with both techniques.
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Affiliation(s)
- J van der Linden
- Division of Cardiothoracic Anaesthesia and Intensive Care, Huddinge University Hospital, Stockholm, Sweden
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