Intracranial blood flow velocity after head injury: relationship to severity of injury, time, neurological status and outcome

Prognostic properties of the association between the S‑100B protein levels and the mean cerebral blood flow velocity in patients diagnosed with severe traumatic brain injury

Craniocerebral injury (CBI) is tissue damage caused by a sudden mechanical force. CBI can result in neurological, neuropsychological and psychiatric dysfunctions. Currently, the severity of CBI is assessed using the Glasgow Coma Scale, brain perfusion pressure measurements, transcranial Doppler tests and biochemical markers. This study aimed to determine the applicability of the S-100B protein levels and the time-averaged mean maximum cerebral blood flow velocity (V_mean) as a means of predicting the treatment outcomes of CBI in the first 4 days of hospitalization. The results validated the standard reference ranges previously proposed for the concentration of S-100B (0.05-0.23 µg/l) and the mean of cerebral blood flow velocity (30.9 to 74.1 cm/sec). The following stratification scheme was used to predict the success of treatment: Patients with a Glasgow Outcome Scale (GOS) score ≥4 or GOS <4 were stratified into ‘favorable’ and ‘unfavorable’ groups, respectively. The favorable group showed relatively constant levels of the S-100B protein close to the normal range and exhibited an increase in V_mean, but this was still within the normal range. The unfavorable group exhibited a high level of S-100B protein and increased V_mean outside of the normal ranges. The changes in the levels of S-100B in the unfavorable and favorable groups were -0.03 and -0.006 mg/l/h, respectively. Furthermore, the rate of decrease in the V_mean value in the unfavorable and favorable groups were -0.26 and -0.18 cm/sec/h, respectively. This study showed that constant levels of S-100B protein, even slightly above the normal range, associated with an increase in V_mean was indicative of a positive therapeutic outcome. However, additional research is required to obtain the appropriate statistical strength required for clinical practice.

Usability of the Level of the S100B Protein, the Gosling Pulsatility Index, and the Jugular Venous Oxygen Saturation for the Prediction of Mortality and Morbidity in Patients with Severe Traumatic Brain Injury

The high frequency of traumatic brain injury imposes severe economic stress on health and insurance services. The objective of this study was to analyze the association between the serum S100B protein, the Gosling pulsatility index (PI), and the level of oxygen saturation at the tip of the internal jugular vein (SjVO2%) in patients diagnosed with severe TBI. The severity of TBI was assessed by a GCS score ≤ 8 stratified by Glasgow outcome scale (GOS) measured on the day of discharge from the hospital. Two groups were included: GOS < 4 (unfavorable group (UG)) and GOS ≥ 4 (favorable group (UG)). S100B levels were higher in the UG than in the FG. PI levels in the UG were also substantially higher than in the FG. There were similar levels of SjVO2 in the two groups. This study confirmed that serum S100B levels were higher in patients with unfavorable outcomes than in those with favorable outcomes. Moreover, a clear demarcation in PI between unfavorable and FGs was observed. This report shows that mortality and morbidity rates in patients with traumatic brain injury can be assessed within the first 4 days of hospitalization using the S100B protein, PI values, and SjVO2.

Utility of Transcranial Doppler in Moderate and Severe Traumatic Brain Injury: A Narrative Review of Cerebral Physiologic Metrics

Since its creation in the 1980s, transcranial Doppler (TCD) has provided a method of non-invasively monitoring cerebral physiology and has become an invaluable tool in neurocritical care. In this narrative review, we examine the role TCD has in the management of the moderate and severe traumatic brain injury (TBI) patient. We examine the principles of TCD and the ways in which it has been applied to gain insight into cerebral physiology following TBI, as well as explore the clinical evidence supporting these applications. Its usefulness as a tool to non-invasively determine intracranial pressure, detect post-traumatic vasospasm, predict patient outcome, and assess the state of cerebral autoregulation are all explored.

Management of severe traumatic brain injury (first 24hours)

The latest French Guidelines for the management in the first 24hours of patients with severe traumatic brain injury (TBI) were published in 1998. Due to recent changes (intracerebral monitoring, cerebral perfusion pressure management, treatment of raised intracranial pressure), an update was required. Our objective has been to specify the significant developments since 1998. These guidelines were conducted by a group of experts for the French Society of Anesthesia and Intensive Care Medicine (Société francaise d'anesthésie et de réanimation [SFAR]) in partnership with the Association de neuro-anesthésie-réanimation de langue française (ANARLF), The French Society of Emergency Medicine (Société française de médecine d'urgence (SFMU), the Société française de neurochirurgie (SFN), the Groupe francophone de réanimation et d'urgences pédiatriques (GFRUP) and the Association des anesthésistes-réanimateurs pédiatriques d'expression française (ADARPEF). The method used to elaborate these guidelines was the Grade^® method. After two Delphi rounds, 32 recommendations were formally developed by the experts focusing on the evaluation the initial severity of traumatic brain injury, the modalities of prehospital management, imaging strategies, indications for neurosurgical interventions, sedation and analgesia, indications and modalities of cerebral monitoring, medical management of raised intracranial pressure, management of multiple trauma with severe traumatic brain injury, detection and prevention of post-traumatic epilepsia, biological homeostasis (osmolarity, glycaemia, adrenal axis) and paediatric specificities.

Stroke risk and outcomes in patients with traumatic brain injury: 2 nationwide studies

OBJECTIVE

To investigate whether patients with traumatic brain injury (TBI) have an increased risk of stroke or poststroke mortality.

PARTICIPANTS AND METHODS

Using Taiwan's National Health Insurance Research Database, we conducted a retrospective cohort study of 30,165 patients with new TBI and 120,660 persons without TBI between January 1, 2000, and December 31, 2004. The risk of stroke was compared between 2 cohorts through December 31, 2008. To investigate the association between in-hospital mortality after stroke and history of TBI, we conducted a case-control study of 7751 patients with newly diagnosed stroke between January 1, 2005, and December 31, 2008.

RESULTS

The TBI cohort had an increased stroke risk (hazard ratio [HR], 1.98; 95% CI, 1.86-2.11). Among patients with stroke, those with a history of TBI had a higher risk of poststroke mortality compared with those without TBI (odds ratio, 1.57; 95% CI, 1.13-2.19). In the TBI cohort, factors associated with stroke were history of TBI hospitalization (HR, 3.14; 95% CI, 2.77-3.56), emergency care for TBI (HR, 3.37; 95% CI, 2.88-3.95), brain hemorrhage (HR, 2.69; 95% CI, 2.43-2.99), skull fracture (HR, 3.00; 95% CI, 2.42-3.71), low income (HR, 2.65; 95% CI, 2.16-3.25), and high medical expenditure for TBI care (HR, 2.26; 95% CI, 2.09-2.43). The severity of TBI was also correlated with poststroke mortality.

CONCLUSIONS

Traumatic brain injury was associated with risk of stroke and poststroke mortality. The relationship between TBI and poststroke mortality does not seem to transcend all age groups. This research shows the importance of prevention, early recognition, and treatment of stroke in this vulnerable population.

Transcranial Doppler ultrasound: technique and application

Transcranial Doppler (TCD) ultrasound provides rapid, noninvasive, real-time measures of cerebrovascular function. TCD can be used to measure flow velocity in the basal arteries of the brain to assess relative changes in flow, diagnose focal vascular stenosis, or to detect embolic signals within these arteries. TCD can also be used to assess the physiologic health of a particular vascular territory by measuring blood flow responses to changes in blood pressure (cerebral autoregulation), changes in end-tidal CO2 (cerebral vasoreactivity), or cognitive and motor activation (neurovascular coupling or functional hyperemia). TCD has established utility in the clinical diagnosis of a number of cerebrovascular disorders such as acute ischemic stroke, vasospasm, subarachnoid hemorrhage, sickle cell disease, as well as other conditions such as brain death. Clinical indication and research applications for this mode of imaging continue to expand. In this review, the authors summarize the basic principles and clinical utility of TCD and provide an overview of a few TCD research applications.

[Non-invasive evaluation of intracranial pressure: how and for whom?]

The invasive monitoring of intracranial pressure is useful in circumstances associated with high-risk of raised intracranial pressure. However the placement of intracranial probe is not always possible and non-invasive assessment of intracranial pressure may be useful, particularly in case of emergencies. Transcranial Doppler measurements allow the estimation of perfusion pressure with the pulsatility index. Recently, new ultrasonographic methods of cerebral monitoring have been developed: the diameter of the optic nerve sheath diameter, a surrogate marker of raised intracranial pressure and the estimation of median shift line deviation.

The pathophysiology of concussions in youth

Mild traumatic brain injury, especially sport-related concussion, is common among young persons. Consequences of transient pathophysiologic dysfunction must be considered in the context of a developing or immature brain, as must the potential for an accumulation of damage with repeated exposure. This review summarizes the underlying neurometabolic cascade of concussion, with emphasis on the young brain in terms of acute pathophysiology, vulnerability, alterations in plasticity and activation, axonal injury, and cumulative risk from chronic, repetitive damage, and discusses their implications in the context of clinical care for the concussed youth, highlighting areas for future investigation.

Transcranial Doppler in children

Transcranial Doppler US, a non-invasive tool for evaluating the cerebral arteries, has evolved significantly during the last two decades. This review describes the practical procedure, and summarises and illustrates its established and "work-in-progress" indications in children. Indications for a transcranial Doppler US examination include, but are not limited to: (1) evaluation of cerebral blood flow velocities in the circle of Willis in patients with sickle cell anaemia to guide transfusion therapy; (2) diagnosis and follow-up of vasculopathy, such as moyamoya disease; (3) diagnosis and monitoring of acute cerebrovascular disorders in intensive care patients, in particular following traumatic brain injury, and during cardiovascular surgery; and (4) confirmation of a clinical diagnosis of brain death by documentation of cerebral circulatory arrest.

Traumatic brain injury: neuroprotective anaesthetic techniques, an update

Traumatic brain injuries remain an area of great challenge to both neurosurgeons and neuroanaesthesiologists. The management of these injuries starts at the scene of the accident. However, strategies for preventing secondary brain injury and its sequelae are continuing to evolve. These strategies include the use of pharmacological and nonpharmacological techniques. Preventing hypoxia and the use of hypertonic saline have been shown to have favourable results on the outcome of these injuries. The use of isoflurane has been shown to have a neuronprotective effect. Propofol is thought to be the future drug of choice because of its neuroprotective properties, although these still need to be further proven through research. In this review an understanding of the pathophysiology of traumatic brain injury will be outlined in order to understand the effects of pharmacological and nonpharmacological agents on secondary brain injury.

Prehospital management of traumatic brain injury

The aim of this study was to review the current protocols of prehospital practice and their impact on outcome in the management of traumatic brain injury. A literature review of the National Library of Medicine encompassing the years 1980 to May 2008 was performed. The primary impact of a head injury sets in motion a cascade of secondary events that can worsen neurological injury and outcome. The goals of care during prehospital triage, stabilization, and transport are to recognize life-threatening raised intracranial pressure and to circumvent cerebral herniation. In that process, prevention of secondary injury and secondary insults is a major determinant of both short- and longterm outcome. Management of brain oxygenation, blood pressure, cerebral perfusion pressure, and raised intracranial pressure in the prehospital setting are discussed. Patient outcomes are dependent upon an organized trauma response system. Dispatch and transport timing, field stabilization, modes of transport, and destination levels of care are addressed. In addition, special considerations for mass casualty and disaster planning are outlined and recommendations are made regarding early response efforts and the ethical impact of aggressive prehospital resuscitation. The most sophisticated of emergency, operative, or intensive care units cannot reverse damage that has been set in motion by suboptimal protocols of triage and resuscitation, either at the injury scene or en route to the hospital. The quality of prehospital care is a major determinant of long-term outcome for patients with traumatic brain injury.

Transcranial Doppler for evaluation of cerebral autoregulation

Transcranial Doppler ultrasound (TCD) can measure cerebral blood flow velocity in the main intracranial vessels non-invasively and with high accuracy. Combined with the availability of non-invasive devices for continuous measurement of arterial blood pressure, the relatively low cost, ease-of-use, and excellent temporal resolution of TCD have stimulated the development of new techniques to assess cerebral autoregulation in the laboratory or bedside using a dynamic approach, instead of the more classical 'static' method. Clinical applications have shown consistent results in certain conditions such as severe head injury and carotid artery disease. Studies in syncopal patients revealed a more complex pattern due to aetiological non-homogeneity and methodological limitations mainly due to inadequate sample-size. Different analytical models to quantify autoregulatory performance have also contributed to the diversity of results in the literature. The review concludes with specific recommendations for areas where further validation and research are needed to improve the reliability and usefulness of TCD in clinical practice.

Changes in cerebral blood flow and oxygen extraction during post-resuscitation syndrome

INTRODUCTION

Most survivors of out-of-hospital cardiac arrest (OHCA) will die subsequently from post-anoxic encephalopathy. In animals, the severity of brain damage is mainly influenced by the duration of cardiac arrest and also by the cerebral blood flow (CBF) and oxygen extraction (CEO2) abnormalities observed during the post-resuscitation period. The aim of our study was to describe CBF and CEO2 modifications during the first 72 h in OHCA patients treated by induced mild hypothermia.

METHODS

Consecutive OHCA patients were studied every 12 h over 72 h. Diastolic flow velocities (dFV), mean flow velocities (mFV) and pulsatility index (PI) were assessed by transcranial doppler (TCD) as an estimate of CBF changes. Simultaneous measurements of CEO2 were obtained using retrograde jugular catheterisation.

RESULTS

Eighteen patients (61 [47-74] years) were studied (12 non-survivors and 6 survivors). At admission, mFV values were low (27.3 [21.5-33.6]cm/s) but reached normal values after 72 h (50.5 [36.7-58.1]cm/s). Initial PI values were high (1.6 [1.3-1.9]) but reached normal values after 72 h (1.04 [0.82-1.2]). No differences were found between survivors and non-survivors regarding these CBF estimates. CEO2 values were quite normal at admission (20.4 [11-27%]) but decreased over time in non-survivors until H72 (25.8% [19.3-31.1] versus 5.7% [5.1-11.5], p=0.02).

CONCLUSION

Cerebral haemodynamic and oxygenation values are altered considerably but evolve during the first 72 h following resuscitation after cardiac arrest. In particular, these changes may lead to a mismatch between CBF and CEO2 leading to a "luxurous perfusion" in non-survivors.

Transcranial doppler ultrasonography as an early outcome forecaster following severe brain injury

Knowledge of post-traumatic cerebral haemodynamic disturbances might be beneficial for predicting the management outcome when measuring the basal cerebral arteries blood flow velocity by ultrasonic transcranial Doppler device immediately after severe head injury. Thirty patients who sustained severe brain injury underwent an early blood velocity measuring by transcranial Doppler ultrasonography during a 1-year period of study. The standard technique of measuring the mean blood flow velocity in the middle cerebral artery was applied. The outcome was assessed at 6-month follow-up by the Glasgow Outcome Score. The middle cerebral artery low blood flow velocity, and the increased values of the pulsatility index significantly correlated to an unfavourable outcome. Transcranial Doppler ultrasonography for measuring the middle cerebral artery blood flow velocity has been proved worthy as a possible predictor of severe head injury management outcome. This non-invasive and simple procedure could be engaged in the daily management of severely brain-injured patients.

Transcranial Doppler ultrasound goal-directed therapy for the early management of severe traumatic brain injury

OBJECTIVE

To evaluate the usefulness of early transcranial Doppler ultrasound (TCD) goal-directed therapy after severe traumatic brain injury initiated before invasive cerebral monitoring is available.

DESIGN

Prospective, observational clinical study.

SETTING

Surgical intensive care unit, university hospital.

PATIENTS AND PARTICIPANTS

Twenty-four severely brain-injured patients.

INTERVENTIONS

All patients had TCD measurements immediately on admission (T0) and when invasive cerebral monitoring was available (T1). TCD was considered abnormal when two out of three measured values were outside the following limits: Vm<30 cm/s, Vd<20 cm/s, PI > 1.4. When admission TCD was abnormal, attending physicians modified treatment to increase cerebral perfusion pressure.

MEASUREMENTS AND RESULTS

Admission TCD was performed 18+/-11 min (T0) after admission, whereas cerebral invasive monitoring was available 242+/-116 min (T1) after admission. At T0, 11 (46%) patients had abnormal TCD values (group 1) and 13 had normal TCD values (group 2); mean arterial pressure was comparable between groups. All group 1 patients received mannitol and/or norepinephrine. At T1, mean arterial pressure was increased compared to admission in group 1 (105+/-17 mmHg vs. 89+/-15 mmHg, p<0.05) and only two patients had still an abnormal TCD. Although group 1 patients had higher intracranial pressure than those of group 2 (32+/-13 mmHg vs. 22+/-10 mmHg, p<0.01), both cerebral perfusion pressure and jugular venous oxygen saturation were comparable between the groups.

CONCLUSIONS

The use of TCD at hospital admission allows identification of severely brain-injured patients with brain hypoperfusion. In such high-risk patients, early TCD goal-directed therapy can restore normal cerebral perfusion and might then potentially help in reducing the extent of secondary brain injury.

Applications of transcranial Doppler in the ICU: a review

OBJECTIVE

Transcranial Doppler (TCD) ultrasonography is a technique that uses a hand-held Doppler transducer (placed on the surface of the cranial skin) to measure the velocity and pulsatility of blood flow within the intracranial and the extracranial arteries. This review critically evaluates the evidence for the use of TCD in the critical care population.

DISCUSSION

TCD has been frequently employed for the clinical evaluation of cerebral vasospasm following subarachnoid haemorrhage (SAH). To a lesser degree, TCD has also been used to evaluate cerebral autoregulatory capacity, monitor cerebral circulation during cardiopulmonary bypass and carotid endarterectomies and to diagnose brain death. Technological advances such as M mode, colour Doppler and three-dimensional power Doppler ultrasonography have extended the scope of TCD to include other non-critical care applications including assessment of cerebral emboli, functional TCD and the management of sickle cell disease.

CONCLUSIONS

Despite publications suggesting concordance between TCD velocity measurements and cerebral blood flow there are few randomized controlled studies demonstrating an improved outcome with the use of TCD monitoring in neurocritical care. Newer developments in this technology include venous Doppler, functional Doppler and use of ultrasound contrast agents.

Posttraumatic vasospasm: the epidemiology, severity, and time course of an underestimated phenomenon: a prospective study performed in 299 patients

OBJECT

The purpose of this prospective study was to evaluate the cumulative incidence, duration, and time course of cerebral vasospasm after traumatic brain injury (TBI) in a cohort of 299 patients.

METHODS

Transcranial Doppler (TCD) ultrasonography studies of blood flow velocity in the middle cerebral and basilar arteries (VMCA and VBA, respectively) were performed at regular intervals during the first 2 weeks posttrauma in association with 133Xe cerebral blood flow (CBF) measurements. According to current definitions of vasospasm, five different criteria were used to classify the patients: A (VMCA > 120 cm/second); B (VMCA > 120 cm/second and a Lindegaard ratio [LR] > 3); C (spasm index [SI] in the anterior circulation > 3.4); D (VBA > 90 cm/second); and E (SI in the posterior circulation > 2.5). Criteria C and E were considered to represent hemodynamically significant vasospasm. Mixed-effects spline models were used to analyze the data of multiple measurements with an inconsistent sampling rate. Overall 45.2% of the patients demonstrated at least one criterion for vasospasm. The patients in whom vasospasm developed were significantly younger and had lower Glasgow Coma Scale scores on admission. The normalized cumulative incidences were 36.9 and 36.2% for patients with Criteria A and B, respectively. Hemodynamically significant vasospasm in the anterior circulation (Criterion C) was found in 44.6% of the patients, whereas vasospasm in the BA-Criterion D or E-was found in only 19 and 22.5% of the patients, respectively. The most common day of onset for Criteria A, B, D, and E was postinjury Day 2. The highest risk of developing hemodynamically significant vasospasm in the anterior circulation was found on Day 3. The daily prevalence of vasospasm in patients in the intensive care unit was 30% from postinjury Day 2 to Day 13. Vasospasm resolved after a duration of 5 days in 50% of the patients with Criterion A or B and after a period of 3.5 days in 50% of those patients with Criterion D or E. Hemodynamically significant vasospasm in the anterior circulation resolved after 2.5 days in 50% of the patients. The time course of that vasospasm was primarily determined by a decrease in CBF.

CONCLUSIONS

The incidence of vasospasm after TBI is similar to that following aneurysmal subarachnoid hemorrhage. Because vasospasm is a significant event in a high proportion of patients after severe head injury, close TCD and CBF monitoring is recommended for the treatment of such patients.

Trans-cranial Doppler in severe head injury: Evaluation of pattern of changes in cerebral blood flow velocity and its impact on outcome

BACKGROUND

Trans-cranial Doppler (TCD) studies after head injury have been done in the first 24 hours after injury and do not specify the exact interval between injury and time of recordings. We have studied cerebral blood flow changes in patients with severe head injury using serial TCD starting within 6 hours after trauma, and present our findings and its correlation with clinical outcome.

METHODS

Thirty-two patients with closed severe brain injuries formed the study group. Six-hourly serial TCD studies were done starting within 6 hours after trauma until 48 hours after trauma or death of the patient, whichever was earlier. Flow velocities of the extracranial internal carotid (V(EC-ICA)) and middle cerebral artery (V(MCA)) were recorded to identify vasospasm, hyperemia, or oligemia. Serial changes in flow velocities were correlated with the clinical outcome of the patients at 12 months' follow-up after injury.

RESULT

Oligemia (n = 30) and vasospasm (n = 2) were the earliest changes observed within 6 hours of trauma. In the oligemia group, persistent oligemia (n = 14), hyperemia (n = 6), normal flow velocity (n = 5), and vasospasm developing within 24 hours (n = 5) were observed. Eight patients developed vasospasm after 24 hours. All patients with persistent oligemia and vasospasm developing within 24 hours had poor outcome.

CONCLUSION

Oligemia is the most common change within 6 hours of head injury. Persistence of oligemia beyond 24 hours is associated with poor outcome. Early (within 24 hours posttrauma) onset of vasospasm is associated with poor outcome; however, delayed (>24 hours after trauma) vasospasm is not associated with poor outcome.

Transcranial Doppler to detect on admission patients at risk for neurological deterioration following mild and moderate brain trauma

OBJECTIVE

To investigate the contribution of transcranial Doppler measurements obtained in the emergency room for detecting patients with secondary neurological deterioration after mild or moderate brain trauma.

DESIGN AND SETTING

Prospective cohort study in the emergency room in a university teaching hospital.

PATIENTS

Seventy-eight adult patients admitted to the emergency room after a traumatic brain injury (TBI), including 42 patients with Glasgow Coma Score 14-15 and 36 with 9-13.

MEASUREMENTS AND RESULTS

All patients had transcranial Doppler measurements on both middle cerebral arteries and computed tomography on admission. Neurological outcome was assessed 7 days after trauma. Of the patients included 7 and 10 had secondary neurological deterioration after mild and moderate TBI, respectively. On admission these groups of patients had significantly more injuries on computed tomography using the Trauma Coma Data Bank classification and higher pulsatility index using transcranial Doppler than the patients having no subsequent neurological worsening.

CONCLUSIONS

Increased pulsatility index after mild or moderate TBI is a reason for concern about the possibility of further neurological deterioration. Computed tomography and Doppler measurements could be combined to detect on admission patients at risk for secondary neurological deterioration in order to improve their initial disposition.

[Prognostic factors in severe head injury]

The knowledge of the so called prognostic factors or indicators involved in severe head injury (SHI) is an issue of great interest to make predictions about the future of patients with this pathology. Those indicators constitute the basic elements of the different prognostic formulas or models carried out in order to make predictions in SHI. The mentioned models, therefore, will be constructed by a group of variables (prognostic indicators or factors) and several scales (prognostic scales) that are useful for measuring the final outcome of these patients. In this paper we resume, after an exhaustive review of the literature, the knowledge about the prognostic factors related to SHI. These indicators have been classified as follows: clinical, radiological, physiological, and biochemical. Moreover, we have briefly described the prognostic scales more commonly used in SHI.

[Minor head injury management in Spain: a multicenter national survey]

INTRODUCTION AND OBJECTIVES

Despite of the high incidence of minor head injury, there is still controversy and disparity of criteria regarding its management. The lack of consensual protocols and clinical guidelines can lead to deficiencies in the attention to these patients and to inadequate use of resources. The objective of this study has been to describe the present situation of the management of this entity in the neurosurgical departments of the Spanish public hospitals, and to compare it with other European countries.

MATERIAL AND METHODS

A 57-item questionnaire regarding different aspects of minor head injury was designed and distributed to the 66 neurosurgical departments of the Spanish National Health System between December 1999 and February 2000.

RESULTS

A 83.3% of responses were obtained. More than 92,000 patients per year are assisted at the Spanish third-level hospitals (general hospitals) after suffering a minor head injury. In-hospital on duty neurosurgeons are not available in 49.1% of the Spanish neurosurgical departments. Only in 7.3% of the centres the neurosurgeon is the first physician that assists these patients. However, in 52.7% of the hospitals neurosurgical evaluation is required if the patient refers transient loss of consciousness. A GCS score of 13 is still included in the group of minor head injuries in 29.1% of the centres. Although 89.1% of the surveyed neurosurgical departments considered as satisfactory the attention they provide to these patients, 85.5% think that it would be convenient to elaborate clinical guidelines. Cranial x-ray is considered a useful diagnostic tool by only 38.2% of the centres, however, 89.1% of them still use it as a routine. CT-scan is systematically indicated in all patients after suffering a mild head trauma only in 5.5% of the centres, although it is completely available in 74.5% of them. The study of economical costs shows that choosing cranial CT as screening tool in these patients would mean a 40.6% reduction in costs compared to a management based on x-ray plus in-hospital observation.

CONCLUSIONS

This study shows the inter-hospital variability of minor head injury management in Spain. Clinical guidelines are considered as positive and necessary. Although the Spanish situation is similar to that in other European countries, following the tendency toward a broader cranial CT utilisation, would improve diagnosis profitability and economical efficiency. The results of this study may contribute to the creation of consensual protocols and clinical guidelines in our country that help in daily practice decision-making optimising assistance quality.

Pediatric trauma. Anesthesia management

Prevention of childhood injury remains the cornerstone of reducing the number of children who present for post-traumatic surgical intervention. Beyond prevention, the next best step is the accurate diagnosis and treatment of traumatic injury. Anesthesiologists contribute to this step by providing timely resuscitation and optimal care to avoid secondary injury. This article classifies trauma in children into different categories depending on the location of the injury. Trauma, of course, is rarely focal, and is often a multisystem entity. With knowledge in management for each subset of trauma, one may be efficient in prioritizing injury and have a good understanding of the appropriate management of the pediatric patient with multiple traumatic injuries.

Severe traumatic brain injury

In western countries, injuries remain the leading cause of death in young adults (Jennett B. Epidemiology of head injury. J Neurol Neurosurg Psychiatry 1996; 60: 362-369). Worldwide, injuries are estimated to account for 15% of the burden of death and disability, and are projected to account for 20% in 2020 (Ad Hoc Committee on Health Research Relating to Future Intervention Options. Investing in Health Research and Development (Document TDR/Gen/96.1). Geneva: World Health Organisation, 1996). In developing countries road traffic injuries in particular are increasing in incidence and injuries are projected to be the third leading cause of death and disability worldwide by 2020 (Ad Hoc Committee on Health Research Relating to Future Intervention Options. Investing in Health Research and Development (Document TDR/Gen/96.1). Geneva: World Health Organisation, 1996). Head injury accounts for up to half of all deaths from trauma (Kraus J. Epidemiology of head injury. In: Cooper PR, Ed. Head Injury, 3rd ed. Baltimore, MD: William Wilkins, 1993), and in addition to causing death often causes severe and long-lasting functional impairment in survivors.

Evaluating the outcome of severe head injury with transcranial Doppler ultrasonography

The authors conducted a study to determine the value of transcranial Doppler (TCD) ultrasonography in evaluating the outcome of severely head injured patients and to correlate the TCD values with those obtained from intracranial pressure (ICP) and cerebral perfusion pressure (CPP) monitoring. The authors conducted a prospective study of 125 patients with severe head injury (Glascow Coma Scale scores of less than 9) who underwent TCD ultrasonography according to the standard technique of insonating the middle cerebral artery (MCA) and measuring the mean blood flow velocity and pulsatility index within the first 24 hours of admission. The ICP and CPP values, as well as other clinical, analytical, and neuroimaging data, were also recorded. After 6 months, outcome was evaluated using the Glasgow Outcome Scale. Moderate disability and complete recovery were considered "good" outcome; death, vegetative state, and severe disability were considered "poor." In 67 patients (54%) good outcome was demonstrated whereas in 58 (46%) it was poor. The mean blood flow velocity of the MCA in patients with good outcome was 44 cm/second; in those with poor outcomes it was 36 cm/second (p < 0.003). The mean PI in cases of good outcome was 1 whereas in poor outcome was 1.56 (p < 0.0001). The correlations of ICP and CPP to PI were statistically significant (r2 = 0.6; p < 0.0001). When performed in the first 24 hours of severe head injury, TCD ultrasonography is valid in predicting the patient's outcome at 6 months and correlates significantly with ICP and CPP values.

Early changes in middle cerebral artery blood flow velocity after head injury

OBJECT

This study was designed to investigate the incidence of early abnormalities in the cerebral circulation after head injury by relating the results of the initial computerized tomography (CT) scan with transcranial Doppler (TCD) ultrasound readings to see if the side of injury and the outcome can be predicted by using these modalities.

METHODS

Transcranial Doppler ultrasound measurements were obtained in the emergency room in 22 head-injured patients less than 3 hours after injury. The middle cerebral artery (MCA) was insonated using a standard technique. The TCD measurements in each MCA were examined individually; of 39 measurements, 22 (56%) showed a low mean blood flow velocity, 27 (69%) demonstrated a high pulsatility index (PI), and 18 (46%) showed both abnormalities. The side of the cerebrovascular abnormality measured by TCD ultrasound did not appear to be an accurate predictor of the side of the injury as determined on the initial CT scan. Of 13 patients in whom either a space-occupying hematoma or signs of swelling were shown on the initial CT scan, 10 (77%) had an increased PI in one or both MCAs, which is an indication of high flow resistance.

CONCLUSIONS

Transcranial Doppler ultrasound examinations performed while patients are in the emergency room may have a role in determining treatment priorities, especially in those with multiple injuries.

Transiently increased basilar artery flow velocity following severe head injury: a time course transcranial Doppler study

BACKGROUND AND PURPOSE

Transcranial Doppler ultrasonography has been used to study changes in cerebral hemodynamics following head injury. However, most studies evaluated the anterior circulation and little information exists on transcranial Doppler of the vertebrobasilar arteries after head injury.

METHODS

Thirty-two patients with a Glasgow Coma Scale (GCS) score between 4-8 and 11 patients with a GCS score between 9-14 were studied using transcranial Doppler ultrasonography for the first 10 days after injury. Daily variations in the mean blood flow velocities of all major cerebral arteries were recorded.

RESULTS

In patients with GCS score between 4-8, the mean blood flow velocities in the middle cerebral and basilar arteries gradually increased beginning on day 2 postinjury and peaked on the 4th-5th day after injury. Those changes were more prominent, and appeared earlier, in the basilar artery. The ratio between the mean flow velocities of the middle cerebral artery and the basilar artery during the first 4 days was significantly lower than in normal controls, indicating a particular increase of flow velocity in the basilar artery. Nineteen out of 32 patients (60%) with severe head injury showed mean blood flow velocity increased over 75 cm/sec in the basilar artery. Mean blood flow velocity >90 cm/sec in the basilar artery, compatible with vasospasm, was observed in 12 of 32 patients (37%). Spasm in the middle cerebral artery was observed in 12 (37%) of patients; 10 of them also had evidence of basilar artery spasm. On the whole, 14 of 32 (43%) patients had evidence of spasm either in the middle cerebral or basilar arteries or in both. In 5 of 11 patients (50%) with moderate head injury (GCS score 9-14), blood flow velocity in the basilar artery greater than 75 cm/sec was observed, but in only two of them it reached the values over 90 cm/sec. Vasospasm in the middle cerebral artery was noted in one patient.

CONCLUSIONS

A significant number of patients develop increased flow velocities compatible with vasospasm in the basilar artery after severe head injury. This phenomenon may represent an additional factor that contributes to the poor outcome of severely head-injured patients.

Transcranial Doppler ultrasonography in the neurocritical care unit

TCD ultrasonography is a noninvasive means to study the cerebral vasculature. By varying the depth and angle of insonation of a pulsed sound wave, the direction and velocity profile of the cerebral arteries can be ascertained. This can be used to identify areas of focal stenosis and increased resistance and to estimate the adequacy of cerebral flow. TCD ultrasonography commonly is used in SAH to detect cerebral vasospasm. Many centers interpret rising velocities as increasing vessel narrowing and initiate medical strategies based on these values. TCD use in head trauma is less clearly defined. TCD ultrasonography is considered an acceptable confirmatory test for the determination of brain death. TCD ultrasonography is capable of studying dynamic cerebrovascular processes. By being able to determine vessel patency, TCD may become a useful adjuvant to thrombolytic therapy. Continuous monitoring of flow velocities and profiles along with testing to cerebrovascular reserve promises to be a future active area of research.

Identification of posttraumatic ischemia and hyperperfusion by determination of the effect of induced arterial hypertension on carbon dioxide reactivity

BACKGROUND AND PURPOSE

Both ischemia and hyperperfusion are known phenomena that follow traumatic brain injury. Cerebral carbon dioxide reactivity is diminished in both conditions. Differentiation is important because ischemia is thought to be a major factor of secondary neuronal loss and is potentially amenable to therapy by manipulation of cerebral perfusion pressure.

METHODS

The response of transcranial Doppler-based carbon dioxide reactivity to pharmacologically induced hypertension was studied sequentially in 29 patients with severe to moderate head injury to identify ischemia and luxury perfusion. After simultaneous baseline registration of the carbon dioxide reactivity of both middle cerebral arteries by two-channel transcranial Doppler, systolic arterial pressure was raised approximately 20 mm Hg by means of phenylephrine (Neosynephrine) infusion, and the carbon dioxide reactivity test was repeated.

RESULTS

A significant improvement of impaired (< 2%/mm Hg) carbon dioxide reactivity after arterial pressure was raised by 20 mm Hg (signaling ischemia) was found in 32 of 124 evaluated middle cerebral arteries. Further deterioration of impaired reactivity occurred in only four tested hemispheres. While ischemic conditions were identified during the entire study period, hyperperfusion was encountered only after day 3.

CONCLUSIONS

Ischemia after traumatic brain injury is a frequent phenomenon, whereas hyperperfusion is rare. Whether therapeutic optimization of carbon dioxide reactivity can improve the outcome of head-injury patients needs to be evaluated in further studies.

Elevated transcranial Doppler flow velocities after severe head injury: cerebral vasospasm or hyperemia?

Sixty-seven patients (45 males and 22 females) aged 2 to 70 years (mean 36 years) who had suffered closed head injury were investigated with daily transcranial Doppler (TCD) recordings. A total of 470 TCD recordings (mean 7) were made during Days 1 to 14 after admission. Blood flow velocities were determined in the middle cerebral artery (MCA) and the extracranial internal carotid artery (ICA). Twenty-seven (40%) of the 67 patients demonstrated traumatic subarachnoid hemorrhage (tSAH) on the first computerized tomography (CT) scan after the injury. Flow velocities exceeded 100 cm/second in 22 patients. Eleven (41%) of the 27 patients who showed tSAH on the first CT scan developed velocities greater than 100 cm/second, as compared to 11 (28%) of 40 patients without tSAH on CT. Two patients in whom a thick layer of tSAH was revealed on the first CT scan had MCA flow velocities exceeding 200 cm/second for several days. Measurements of cerebral blood flow (CBF) with single-photon emission CT (SPECT) were performed in six tSAH patients who showed TCD flow velocities exceeding 120 cm/second (uni- or bilaterally) to determine whether the increase in velocity reflected vasospasm or hyperemia. The SPECT studies verified ischemia in five patients but revealed general hyperemia in one. The bilateral increase in MCA flow velocities in the latter case was due to high-volume flow through the MCA secondary to elevated CBF rather than arterial narrowing. In one patient with a thick layer of subarachnoid blood on a CT scan obtained at admission, MCA flow velocities exceeded 220 cm/second bilaterally on Day 8 after the head injury. A SPECT measurement obtained on the same day reflected bilateral ischemia. In this patient flow velocities decreased, with a corresponding normalization of CBF, after 5 days of intravenous nimodipine administration. The MCA/ICA ratio correlated well with the distribution of CBF in the six patients studied using SPECT. This report suggests that vasospasm is an important secondary posttraumatic insult in patients suffering severe head injury and, in some cases, is probably treatable by administration of intravenous calcium channel blockers.

Management of raised intracranial pressure

This review has been written at an unfortunate time. Novel questions are being asked of the old therapies and there is an abundance of new strategies both to lower ICP and protect the brain against cerebral ischaemia. In the United Kingdom, the problem is to ensure that appropriate patients continue to be referred to centres where clinical trials of high quality can be undertaken. One of the success stories of the past decade has been the decline in the number of road accidents as a result of seat belt legislation, improvements in car design and the drink/driving laws. Hence, fortunately there are fewer patients with head injuries to treat and it is even more important that patients are appropriately referred if studies to assess efficacy of the new strategies are not to be thwarted. The nihilistic concept that intensive investigation with ICP monitoring for patients with diffuse head injury or brain swelling following evacuation of a haematoma or a contusion has no proven beneficial effect on outcome, requires revision. A cocktail of therapies may be required that can be created only when patients are monitored in sufficient detail to reveal the mechanisms underlying their individual ICP problem. Ethical problems may arise over how aggressively therapy for intracranial hypertension should be pursued and for how long. There has always been the concern that cranial decompression or prolonged barbiturate coma may preserve patients but with unacceptably severe disability. Some patients may be salvaged from herniating with massive cerebral infarction with the use of osmotherapy but is the outcome acceptable? Similar considerations apply to some children with metabolic encephalopathies. Where such considerations have been scrutinised in patients with severe head injury, the whole spectrum of outcomes appears to be shifted so that the number of severe disabilities and persistent vegetative states are not increased. However, it is important to be sensitive to such issues based on experience of the particular cause of raised intracranial pressure in a given age group.

Transcranial Doppler-sonography in severe head injury

Ischaemic brain damage is present in over 90% of patients suffering from fatal head injury. Early detection and treatment of ischemia may improve outcome after head trauma. Monitoring of blood flow velocity of the middle cerebral artery by noninvasive transcranial doppler ultrasound provides an alternate means of identifying cerebral ischaemia.