Fever in subarachnoid hemorrhage: relationship to vasospasm and outcome

Clinical response to hypertensive hypervolemic therapy and outcome after subarachnoid hemorrhage

OBJECTIVE

Hypertensive hypervolemic therapy is widely used to treat symptomatic vasospasm after subarachnoid hemorrhage. Few data exist to support a relationship between early clinical response and mortality or functional outcome.

METHODS

In a prospective cohort of 580 subarachnoid hemorrhage patients, we studied 95 patients with acute symptomatic vasospasm who received stepwise volume expansion with crystalloid and/or 5% albumin solution followed by intravenous pressors to maintain systolic blood pressure between 180 and 220 mm Hg. We separately assessed the effects of volume expansion and induced hypertension on the neurological examination during the first 2 hours of each intervention. We used multivariate logistic regression analysis to calculate adjusted odds ratios assessing the relationship between clinical response to hypertensive hypervolemic therapy and 3-month outcome, as measured by the modified Rankin Scale.

RESULTS

Of 95 patients with symptomatic vasospasm, volume expansion was used in 94% (n = 89), of whom 43% had a clinical response; 85% of the patients (n = 81) received pressors, of whom 68% responded. Early clinical improvement attributable to either volume expansion or pressors was not related to the development of infarction on computed tomography, but response to either modality within 2 hours was independently protective against death (adjusted odds ratio, 0.03; P < 0.05) and death-or-severe-disability (modified Rankin Scale score, 4-6; adjusted odds ratio, 0.1; P < 0.05) after adjusting for age, Hunt-Hess grade, angioplasty, and aneurysm size.

CONCLUSION

Subarachnoid hemorrhage patients with symptomatic vasospasm who fail to demonstrate early clinical improvement in response to volume or pressor therapy are at high risk for death or disability. Urgent endovascular intervention in this high-risk patient cohort may be justified.

The evidence for hypothermia as a neuroprotectant in traumatic brain injury

This article reviews published experimental and clinical evidence for the benefits of modest hypothermia in the treatment of traumatic brain injury (TBI). Therapeutic hypothermia has been reported to improve outcome in several animal models of CNS injury and has been successfully translated to specific patient populations. A PubMed search for hypothermia and TBI was conducted, and important papers were selected for review. The research summarized was conducted at major academic institutions throughout the world. Experimental studies have emphasized that hypothermia can affect multiple pathophysiological mechanisms thought to participate in the detrimental consequences of TBI. Published data from several relevant clinical trials on the use of hypothermia in severely injured TBI patients are also reviewed. The consequences of mild to moderate levels of hypothermia introduced by different strategies to the head-injured patient for variable periods of time are discussed. Both experimental and clinical data support the beneficial effects of modest hypothermia following TBI in specific patient populations. Following on such single-institution studies, positive findings from multicenter TBI trials will be required before this experimental treatment can be considered standard of care.

PREDICTORS OF GLOBAL COGNITIVE IMPAIRMENT 1 YEAR AFTER SUBARACHNOID HEMORRHAGE

OBJECTIVE

We sought to determine the frequency, risk factors, and impact on functional outcome and quality of life (QOL) of global cognitive impairment 1 year after subarachnoid hemorrhage.

METHODS

We prospectively evaluated global cognitive status 3 and 12 months after hospitalization with the Telephone Interview for Cognitive Status in 232 subarachnoid hemorrhage survivors. Cognitive impairment was defined as a score of 30 or less (scaled 0 = worst, 51 = best). Logistic regression was performed to calculate adjusted odds ratios (AORs) for impairment at 1 year. Basic activities of daily living were evaluated with the Barthel Index, instrumental activities of daily living were assessed with the Lawton scale, and QOL was evaluated with the Sickness Impact Profile.

RESULTS

The frequency of cognitive impairment was 27% at 3 months and 21% at 12 months. After the effects of age, education, and race/ethnicity were controlled for, risk factors for cognitive impairment at 12 months included anemia treated with transfusion (AOR, 3.4; P = 0.006), any temperature level higher than 38.6°C (AOR, 2.7; P = 0.016), and delayed cerebral ischemia (AOR, 3.6; P = 0.01). Among cognitively impaired patients at 3 months, improvement at 1 year occurred in 34% and was associated with more than 12 years of education and the absence of fever higher than 38.6°C during hospitalization (P = 0.015). Patients with cognitive impairment at 1 year had worse concurrent QOL and less ability to perform instrumental and basic activities of daily living (all P &lt; 0.001).

CONCLUSION

Global cognitive impairment affects more than 20% of subarachnoid hemorrhage survivors at 1 year, is predicted by fever, anemia treated with transfusion, and delayed cerebral ischemia, and adversely affects functional recovery and QOL.

Relationship between energy balance and complications after subarachnoid hemorrhage

BACKGROUND

Subarachnoid hemorrhage patients are hypermetabolic and at risk for developing medical complications. A relationship was hypothesized between energy balance and complications following subarachnoid hemorrhage.

METHODS

Fifty-eight consecutive poor-grade subarachnoid hemorrhage patients (mean age, 58; range, 26-86; 66% women) were studied between 2005 and 2007. Caloric intake and energy expenditure were assessed. In-hospital complications over the first 14 days posthemorrhage were defined as renal failure, fever (>38.3 degrees C), any infection, anemia, hyperglycemia (>11 mmol/L), and myocardial infarction. Energy balance was calculated by subtracting energy expenditure from caloric intake.

RESULTS

Enteral nutrition was begun 1 day posthemorrhage (range, 0-5 days). Recommended (mean +/- SD) caloric intake was 28 +/- 3 kcal/kg/d, and the actual was 14 +/- 5 kcal/kg/d. Enteral nutrition accounted for 67% of caloric intake; propofol and dextrose infusions accounted for 33% of caloric intake. Cumulative energy balance over the first 7 days was -117 +/- 53 kcal/kg. The average energy balance during the first 7 days after subarachnoid hemorrhage significantly correlated with the total number of infectious complications (r = -0.5, P < .001) but not medical complications (r = -0.2, P = .1). After adjustment for Hunt-Hess grade, fever, hyperglycemia, and anemia, negative energy balance during the first 7 days after subarachnoid hemorrhage correlated with the number of infectious complications (P = .01).

CONCLUSIONS

Infectious complications after subarachnoid hemorrhage are associated with negative energy balance. Studies are needed to better understand the impact of negative energy balance on outcome after subarachnoid hemorrhage.

Fever control in the neuro-ICU: why, who, and when?

PURPOSE OF REVIEW

Fever in the neurocritical care setting is very common and has a negative impact on outcome of all disease types. Recent advances have made eliminating fever and maintaining normothermia feasible. However, important questions regarding indications and timing remain. The purpose of this review is to analyze the data surrounding the impact of fever across a range of neurologic injuries to better understand the optimal timing and duration of fever control.

RECENT FINDINGS

Meta-analyses have demonstrated that fever at onset and in the acute setting after ischemic brain injury, intracerebral hemorrhage, and cardiac arrest have a negative impact on morbidity and mortality. There are data to support that the impact of fever is sustained for longer durations after subarachnoid hemorrhage and traumatic brain injury. However, there are currently no prospective randomized trials demonstrating the benefit of fever control in these patient populations.

SUMMARY

The negative impact of fever after neurologic injury is well understood. Prospective randomized trials are needed to determine whether the beneficial impact of secondary injury prevention is outweighed by the potential infectious risk of prolonged fever control.

Peak body temperature predicts mortality in critically ill patients without cerebral damage

OBJECTIVES

We investigated whether mortality in intensive care unit (ICU) patients without cerebral damage is associated with fever manifestation and characteristics.

METHODS

Patients admitted to a medical-surgical ICU between October 2005 and July 2006 were prospectively studied. Exclusion criteria were acute brain injury, intracerebral/subarachnoid hemorrhage, ischemic stroke, and brain surgery. An ear-based or axillary thermometer was used to measure body temperature. The association between fever (ear-based temperature, >38.3 degrees C), fever characteristics, and ICU mortality was evaluated using univariate and multivariate analysis.

RESULTS

Two hundred and thirty-nine patients were enrolled. Fever was not associated with ICU mortality after adjustment for confounding patient factors. A significant dose-response increase of ICU mortality according to 1 degree C increments of peak body temperature was demonstrated, whereas peak body temperature was an independent predictor of ICU mortality.

CONCLUSION

These findings imply that, although fever is not generally associated with mortality in patients without cerebral damage, it can be harmful and should be suppressed when it becomes very high. Rigorous clinical trials are needed to help establish antipyretic therapy guidelines.

Role of inflammation (leukocyte-endothelial cell interactions) in vasospasm after subarachnoid hemorrhage

BACKGROUND

Delayed vasospasm is the leading cause of morbidity and mortality after aneurysmal subarachnoid hemorrhage (aSAH). This phenomenon was first described more than 50 years ago, but only recently has the role of inflammation in this condition become better understood.

METHODS

The literature was reviewed for studies on delayed vasospasm and inflammation.

RESULTS

There is increasing evidence that inflammation and, more specifically, leukocyte-endothelial cell interactions play a critical role in the pathogenesis of vasospasm after aSAH, as well as in other conditions including meningitis and traumatic brain injury. Although earlier clinical observations and indirect experimental evidence suggested an association between inflammation and chronic vasospasm, recently direct molecular evidence demonstrates the central role of leukocyte-endothelial cell interactions in the development of chronic vasospasm. This evidence shows in both clinical and experimental studies that cell adhesion molecules (CAMs) are up-regulated in the perivasospasm period. Moreover, the use of monoclonal antibodies against these CAMs, as well as drugs that decrease the expression of CAMs, decreases vasospasm in experimental studies. It also appears that certain individuals are genetically predisposed to a severe inflammatory response after aSAH based on their haptoglobin genotype, which in turn predisposes them to develop clinically symptomatic vasospasm.

CONCLUSION

Based on this evidence, leukocyte-endothelial cell interactions appear to be the root cause of chronic vasospasm. This hypothesis predicts many surprising features of vasospasm and explains apparently unrelated phenomena observed in aSAH patients. Therapies aimed at preventing inflammation may prevent and/or reverse arterial narrowing in patients with aSAH and result in improved outcomes.

Use of prolonged hypothermia to treat ischemic and hemorrhagic stroke

Therapeutic (induced) hypothermia (TH) has been extensively studied as a means to reduce brain injury following global and focal cerebral ischemia, intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH). Here, we briefly review the clinical and experimental evidence supporting the use of TH in each condition. We emphasize the importance of systematically evaluating treatment parameters, especially the duration of cooling, in each condition. We contend that TH provides considerable protection after global and focal cerebral ischemia, especially when cooling is prolonged (e.g., >24 h). However, there is presently insufficient evidence to support the clinical use of TH for ICH and SAH. In any case, further animal work is needed to develop optimized protocols for treating cardiac arrest (global ischemia), and to maximize the likelihood of successful clinical translation in focal cerebral ischemia.

Perioperative fever and outcome in surgical patients with aneurysmal subarachnoid hemorrhage

OBJECTIVE

We examined the incidence of perioperative fever and its relationship to outcome among patients enrolled in the Intraoperative Hypothermia for Aneurysm Surgery Trial.

METHODS

One thousand patients with initial World Federation of Neurological Surgeons grades of I to III undergoing clipping of intracranial aneurysms after subarachnoid hemorrhage were randomized to intraoperative normothermia (36 degrees C-37 degrees C) or hypothermia (32.5 degrees C-33.5 degrees C). Fever (> or =38.5 degrees C) and other complications (including infections) occurring between admission and discharge (or death) were recorded. Functional and neuropsychologic outcomes were assessed 3 months postoperatively. The primary outcome variable for the trial was dichotomized Glasgow Outcome Scale (good outcome versus all others).

RESULTS

Fever was reported in 41% of patients. In 97% of these, fever occurred in the postoperative period. The median time from surgery to first fever was 3 days. All measures of outcome were worse in patients who developed fever, even in those without infections or who were World Federation of Neurological Surgeons grade I. Logistic regression analyses were performed to adjust for differences in preoperative factors (e.g., age, Fisher grade, initial neurological status). This demonstrated that fever continued to be significantly associated with most outcome measures, even when infection was added to the model. An alternative stepwise model selection process including all fever-related measures from the preoperative and intraoperative period (e.g., hydrocephalus, duration of surgery, intraoperative blood loss) resulted in the loss of significance for dichotomized Glasgow Outcome Scale, but significant associations between fever and several other outcome measures remained. After adding postoperative delayed ischemic neurological deficits to the model, only worsened National Institutes of Health Stroke Scale score, Barthel Activities of Daily Living index, and discharge destination (home versus other) remained independently associated with fever.

CONCLUSION

These findings suggest that fever is associated with worsened outcome in surgical subarachnoid hemorrhage patients, although, because the association between fever and the primary outcome measure for the trial is dependent on the covariates used in the analysis (particularly operative events and delayed ischemic neurological deficits), we cannot rule out the possibility that fever is a marker for other events. Only a formal trial of fever treatment or prevention can address this issue.

Hyperthermia and fever control in brain injury

Fever in the neurocritical care setting is common and has a negative impact on outcome of all disease types. Meta-analyses have demonstrated that fever at onset and in the acute setting after ischemic brain injury, intracerebral hemorrhage, and cardiac arrest has a negative impact on morbidity and mortality. Data support that the impact of fever is sustained for longer durations after subarachnoid hemorrhage and traumatic brain injury. Recent advances have made eliminating fever and maintaining normothermia feasible. However, there are no prospective randomized trials demonstrating the benefit of fever control in these patient populations, and important questions regarding indications and timing remain. The purpose of this review is to analyze the data surrounding the impact of fever across a range of neurologic injuries to better understand the optimal timing and duration of fever control. Prospective randomized trials are needed to determine whether the beneficial impact of secondary injury prevention is outweighed by the potential risks of prolonged fever control.

Fever burden and functional recovery after subarachnoid hemorrhage

OBJECTIVE

Fever is associated with worse outcome after subarachnoid hemorrhage, but there are few prospective data to quantify this relationship.

METHODS

We prospectively enrolled consecutive aneurysmal or cryptogenic subarachnoid hemorrhage patients and recorded the highest core temperature each calendar day for Day 0 (the day of hemorrhage) through Day 13. Fever burden was defined as the daily highest core temperature minus 100.4 degrees F, summed from admission through Day 13 (temperatures <100.4 degrees F did not contribute to or subtract from fever burden). Outcomes were assessed at 14 days or at the time of hospital discharge with the National Institutes of Health Stroke Scale and modified Rankin Scale, and at 28 days and 3 months with the modified Rankin Scale. Improvement was analyzed with repeated measures analysis of variance.

RESULTS

We prospectively enrolled 94 patients. From 14 days to 28 days to 3 months, functional improvement was related to cumulative fever burden, admission neurological grade, aneurysm obliteration procedure, admission computed tomographic score, vasospasm, and external ventricular drainage. Good-grade patients had worse functional outcomes with increased fever burden, and poor-grade patients improved more over time when fever burden was higher (time by World Federation of Neurological Surgeons grade by fever burden interaction, P < 0.001). Patients with vasospasm (P = 0.04) and patients with higher computed tomographic scores (P = 0.002) had worse 14-day outcomes but improved more over time. Bacteremia and ventriculitis were uncommon (<or=5%) and were not associated with higher fever burden.

CONCLUSION

Cumulative fever burden was associated with worse outcomes in good-grade patients and potential late recovery in poor-grade patients. Effective fever control in febrile subarachnoid hemorrhage patients may improve functional outcomes and hasten recovery.

Therapeutic hypothermia and controlled normothermia in the intensive care unit: practical considerations, side effects, and cooling methods

BACKGROUND

Hypothermia is being used with increasing frequency to prevent or mitigate various types of neurologic injury. In addition, symptomatic fever control is becoming an increasingly accepted goal of therapy in patients with neurocritical illness. However, effectively controlling fever and inducing hypothermia poses special challenges to the intensive care unit team and others involved in the care of critically ill patients.

OBJECTIVE

To discuss practical aspects and pitfalls of therapeutic temperature management in critically ill patients, and to review the currently available cooling methods.

DESIGN

Review article.

INTERVENTIONS

None.

MAIN RESULTS

Cooling can be divided into three distinct phases: induction, maintenance, and rewarming. Each has its own risks and management problems. A number of cooling devices that have reached the market in recent years enable reliable maintenance and slow and controlled rewarming. In the induction phase, rapid cooling rates can be achieved by combining cold fluid infusion (1500-3000 mL 4 degrees C saline or Ringer's lactate) with an invasive or surface cooling device. Rapid induction decreases the risks and consequences of short-term side effects, such as shivering and metabolic disorders. Cardiovascular effects include bradycardia and a rise in blood pressure. Hypothermia's effect on myocardial contractility is variable (depending on heart rate and filling pressure); in most patients myocardial contractility will increase, although mild diastolic dysfunction can develop in some patients. A risk of clinically significant arrhythmias occurs only if core temperature decreases below 30 degrees C. The most important long-term side effects of hypothermia are infections (usually of the respiratory tract or wounds) and bedsores.

CONCLUSIONS

Temperature management and hypothermia induction are gaining importance in critical care medicine. Intensive care unit physicians, critical care nurses, and others (emergency physicians, neurologists, and cardiologists) should be familiar with the physiologic effects, current indications, techniques, complications and practical issues of temperature management, and induced hypothermia. In experienced hands the technique is safe and highly effective.

[Deleterious role of hyperthermia in neurocritical care]

Fever is a secondary brain injury and may worsen neurological prognosis of neurological intensive care unit (NICU) patients. In response to an immunological threat, fever associates various physiological reactions, including hyperthermia. Its definition may vary but the most commonly used threshold is 37.5 degrees C. In animal studies, hyperthermia applied before, during or after cerebral ischemia may increase the volume of ischemic lesions. The mechanism of this effect may include increase in blood brain barrier permeability, increase in excitatory amino acid release and increase in free radical production. In NICU patients, fever is frequent, occurring in up to 20-30% of patients. Moreover, after haemorrhagic stroke, fever has been reported in 40-50% of patients. In half of the patients, fever may be related to an infectious cause but in more than 25% of patients, hyperthermia may be of central origin. After ischemic stroke, hyperthermia during the first 72 hours is associated with an increase in infarct size and increase in morbidity and mortality. This holds true also after subarachnoid haemorrhage. After traumatic brain injury, fever is not related to mortality but may increase morbidity. Whereas no causal link has been established between fever and unfavourable outcome, it seems reasonable to treat hyperthermia in patients suffering from brain injuries. In such patients, antipyretics have a moderate efficacy. In case of failure, they should be replaced by physical cooling techniques.

RESUSCITATION AND CRITICAL CARE OF POOR-GRADE SUBARACHNOID HEMORRHAGE

AS OUTCOMES HAVE improved for patients with aneurysmal subarachnoid hemorrhage, most mortality and morbidity that occur today are the result of severe diffuse brain injury in poor-grade patients. The premise of this review is that aggressive emergency cardiopulmonary and neurological resuscitation, coupled with early aneurysm repair and advanced multimodality monitoring in a specialized neurocritical care unit, offers the best approach for achieving further improvements in subarachnoid hemorrhage outcomes. Emergency care should focus on control of elevated intracranial pressure, optimization of cerebral perfusion and oxygenation, and medical and surgical therapy to prevent rebleeding. In the postoperative period, advanced monitoring techniques such as continuous electroencephalography, brain tissue oxygen monitoring, and microdialysis can detect harmful secondary insults, and may eventually be used as end points for goal-directed therapy, with the aim of creating an optimal physiological environment for the comatose injured brain. As part of this paradigm shift, it is essential that aggressive surgical and medical support be linked to compassionate end-of-life care. As neurosurgeons become confident that comfort care can be implemented in a straightforward fashion after a failed trial of early maximal intervention, the usual justification for withholding treatment (survival with neurological devastation) becomes less relevant, and lives may be saved as more patients recover beyond expectations.

Hyperthermia during anaesthesia and intensive care unit stay

Nosocomial hyperthermia (fever) occurs in about 30% of all medical patients at some time during their hospital stay. In patients admitted to the intensive care unit with severe sepsis the incidence of hyperthermia is greater than 90%, while in a specialized neurological critical care unit the incidence is reported as 47%. In contrast, hyperthermia during anaesthesia is rare owing to the impairment of thermoregulation by anaesthetic agents. This article is designed to give an overview on the various causes of hyperthermia with special emphasis on fever during general and regional anaesthesia in general and neurological critical care patients.

Brain injury and fever: hospital length of stay and cost outcomes

Fever has been shown to be related to extended hospital stays in neurologically injured patients. We performed meta-analyses of the impact of fever on length of stay (LOS) in the Intensive Care Unit (ICU) and for total hospital length of stay, including all recent scholarship published since 1/1/1995 pertaining to thermoregulation of neurogenic fever and length of hospital stay. We also developed estimates of the financial impact on hospital costs. Fever was shown to have a large, statistically significant impact on both ICU and hospital LOS. For ICU LOS, combined effect size g = .88, Z = 4.24, P < .0001. For hospital LOS, g = .79, Z = 2.2, P = .0278. Mean additional ICU days = 5.7 days; mean additional hospital days = 8.5 days. We estimate that fever added an average of $17,414 in hospital cost to total hospital stays; mean $13,672 (95% Confidence Interval [CI]: $10,074, $17,270) in additional ICU costs and mean $3,742 (CI: -$1,203, $8,820) in additional routine costs.

Theoretical evaluations of therapeutic systemic and local cerebral hypothermia

PURPOSE

To simulate cerebral temperature behaviour with hypothermia treatment applying different cooling devices and to find the optimal brain temperature monitoring.

METHODS

Models based on hourly temperature values recorded in patients with severe aneurysmal subarachnoid hemorrhage, taking MRI data, thermal conductive properties, metabolism and blood flow into account were applied to different scenarios of hypothermia.

RESULTS

Systemic hypothermia by endovascular cooling leads to an uniform temperature decrease within the brain tissue. Cooling with head caps lead to 33 degrees C only in the superficial brain while the deep brain remains higher than 36 degrees C. Cooling with neckbands lead to 35.8 degrees C for dry and 32.8 degrees C for wet skin in the deep brain.

CONCLUSIONS

With head caps temperatures below 36 degrees C cannot be reached in the deep brain tissue, whereas neckbands, covering the carotid triangles, may lead to hypothermic temperatures in the deep brain tissue. Temperature sensors have to be applied at least 2 cm below the cortical surface to give values representative for deep brain tissue.

THERAPEUTIC HYPOTHERMIA IN PATIENTS WITH ANEURYSMAL SUBARACHNOID HEMORRHAGE, REFRACTORY INTRACRANIAL HYPERTENSION, OR CEREBRAL VASOSPASM

OBJECTIVE

To evaluate the feasibility and safety of mild hypothermia treatment in patients with aneurysmal subarachnoid hemorrhage (SAH) who are experiencing intracranial hypertension and/or cerebral vasospasm (CVS).

METHODS

Of 441 consecutive patients with SAH, 100 developed elevated intracranial pressure and/or symptomatic CVS refractory to conventional treatment. Hypothermia (33–34°C) was induced and maintained until intracranial pressure normalized, CVS resolved, or severe side effects occurred.

RESULTS

Thirteen patients were treated with hypothermia alone, and 87 were treated with hypothermia in combination with barbiturate coma. Sixty-six patients experienced poor-grade SAH (Hunt and Hess Grades IV and V) and 92 had Fisher Grade 3 and 4 bleedings. The mean duration of hypothermia was 169 ± 104 hours, with a maximum of 16.4 days. The outcome after 1 year was evaluated in 90 of 100 patients. Thirty-two patients (35.6%) survived with good functional outcome (Glasgow Outcome Scale [GOS] score, 4 and 5), 14 (15.5%) were severely disabled (GOS score, 3), 1 (1.1%) was in a vegetative state (GOS score, 2), and 43 (47.8%) died (GOS score, 1). The most frequent side effects were electrolyte disorders (77%), pneumonia (52%), thrombocytopenia (47%), and septic shock syndrome (40%). Of 93 patients with severe side effects, 6 (6.5%) died as a result of respiratory or multi-organ failure.

CONCLUSION

Prolonged systemic hypothermia may be considered as a last-resort option for a carefully selected group of SAH patients with intracranial hypertension or CVS resistant to conventional treatment. However, complications associated with hypothermia require elaborate protocols in general intensive care unit management.

The burden of the systemic inflammatory response predicts vasospasm and outcome after subarachnoid hemorrhage

INTRODUCTION

Subarachnoid hemorrhage (SAH) can trigger immune activation sufficient to induce the systemic inflammatory response syndrome (SIRS). This may promote both extra-cerebral organ dysfunction and delayed cerebral ischemia, contributing to worse outcome. We ascertained the frequency and predictors of SIRS after spontaneous SAH, and determined whether degree of early systemic inflammation predicted the occurrence of vasospasm and clinical outcome.

METHODS

Retrospective analysis of prospectively collected data on 276 consecutive patients admitted to a neurosciences intensive care unit with acute, non-traumatic SAH between 2002 and 2005. A daily SIRS score was derived by summing the number of variables meeting standard criteria (HR >90, RR >20, Temperature >38 degrees C, or <36 degrees C, WBC count <4,000 or >12,000). SIRS was considered present if two or more criteria were met, while SIRS burden over the first four days was calculated by averaging daily scores. Regression modeling was used to determine the relationship among SIRS burden (after controlling for confounders including infection, surgery, and corticosteroid use), symptomatic vasospasm, and outcome, determined by hospital disposition.

RESULTS

SIRS was present in over half the patients on admission and developed in 85% within the first four days. Factors associated with SIRS included poor clinical grade, thick cisternal blood, larger aneurysm size, higher admission blood pressure, and surgery for aneurysm clipping. Higher SIRS burden was independently associated with death or discharge to nursing home (OR 2.20/point, 95% CI 1.27-3.81). All of those developing clinical vasospasm had evidence of SIRS, with greater SIRS burden predicting increased risk for delayed ischemic neurological deficits (OR 1.77/point, 95% CI 1.12-2.80).

CONCLUSIONS

Systemic inflammatory activation is common after SAH even in the absence of infection; it is more frequent in those with more severe hemorrhage and in those who undergo surgical clipping. Higher burden of SIRS in the initial four days independently predicts symptomatic vasospasm and is associated with worse outcome.

Temperature management in acute neurologic disorders

Temperature management in acute neurologic disorders has received considerable attention in the last 2 decades. Numerous trials of hypothermia have been performed in patients with head injury, stroke, and cardiac arrest. This article reviews the physiology of thermoregulation and mechanisms responsible for hyperpyrexia. Detrimental effects of fever and benefits of normalizing elevated temperature in experimental models are discussed. This article presents a detailed analysis of trials of induced hypothermia in patients with acute neurologic insults and describes methods of fever control.

Impact of fever on outcome in patients with stroke and neurologic injury: a comprehensive meta-analysis

BACKGROUND AND PURPOSE

Many studies associate fever with poor outcome in patients with neurological injury, but this relationship is blurred by divergence in populations and outcome measures. We sought to incorporate all recent scholarship addressing fever in brain-injured patients into a comprehensive meta-analysis to evaluate disparate clinical findings.

METHODS

We conducted a Medline search for articles since January 1, 1995 (in English with abstracts, in humans) and hand searches of references in bibliographies and review articles. Search terms covered stroke, neurological injury, thermoregulation, fever, and cooling. A total of 1139 citations were identified; we retained 39 studies with 67 tested hypotheses contrasting outcomes of fever/higher body temperature and normothermia/lower body temperature in patients with neurological injury covering 14431 subjects. A separate meta-analysis was performed for each of 7 outcome measures. Significance was evaluated with Zc developed from probability values or t values. Correlational effect size, r (es), was calculated for each study and used to derive Cohen's d unbiased combined effect size and relative risk.

RESULTS

Fever or higher body temperature was significantly associated with worse outcome in every measure studied. Relative risk of worse outcome with fever was: mortality, 1.5; Glasgow Outcome Scale, 1.3; Barthel Index, 1.9; modified Rankin Scale, 2.2; Canadian Stroke Scale, 1.4; intensive care length of stay, 2.8; and hospital length of stay, 3.2.

CONCLUSIONS

In the pooled analyses covering 14431 patients with stroke and other brain injuries, fever is consistently associated with worse outcomes across multiple outcome measures.

Medical Management of Patients with Aneurysmal Subarachnoid Haemorrhage

Treating patients with aneurysmal subarachnoid haemorrhage is taking care of acutely ill patients, and should be performed in centres where a multidisciplinary team is available 24 hours a day 7 days a week, and where enough patients are managed to maintain and improve standards of care. There is no medical management that improves outcome by reducing the risk of rebleeding, therefore occlusion of the aneurysm, nowadays preferably by means of coiling, remains an important goal in treating patients with aneurysms. Because the poor outcome after subarachnoid haemorrhage is caused to a large extent by complications other than rebleeding, proper medical management to prevent and treat these complications is therefore essential. On basis of the available evidence, oral (not intravenous) nimodipine should be standard care in patients with subarachnoid haemorrhage. It is rational to refrain from treating hypertension unless cardiac failure develops and to aim for normovolaemia, even in case of hyponatraemia. There is no evidence for prophylactic hypervolaemia, and the strategy of hypervolaemia and hypertension in patients with secondary cerebral ischaemia is based on case reports and uncontrolled observational series of patients. Magnesium sulphate and statins are promising therapies, and large trials on effectiveness in improving clinical outcome are underway. There is no evidence for prophylactic use of anti epileptic drugs, and routine use of corticosteroids should be avoided.

Physical antipyresis in critically ill adults

Nurses use a variety of methods to cool critically ill patients, even though there are no guidelines for the treatment of temperature elevation in this population. In order to determine whether physical methods of antipyresis, such as the application of cooling blankets, are appropriate for use in the ICU, and if so which methods are best, the authors conducted a literature review. Their findings raise concerns about whether external cooling methods should be used at all in the absence of hyperthermia or cerebral damage. In addition, the authors give an overview of the causes and effects of temperature elevation, focusing mostly on fever.A literature review examines external cooling methods for use in the ICU. The findings raise some doubts.

Induced hypothermia and fever control for prevention and treatment of neurological injuries

Increasing evidence suggests that induction of mild hypothermia (32-35 degrees C) in the first hours after an ischaemic event can prevent or mitigate permanent injuries. This effect has been shown most clearly for postanoxic brain injury, but could also apply to other organs such as the heart and kidneys. Hypothermia has also been used as a treatment for traumatic brain injury, stroke, hepatic encephalopathy, myocardial infarction, and other indications. Hypothermia is a highly promising treatment in neurocritical care; thus, physicians caring for patients with neurological injuries, both in and outside the intensive care unit, are likely to be confronted with questions about temperature management more frequently. This Review discusses the available evidence for use of controlled hypothermia, and also deals with fever control. Besides discussing the evidence, the aim is to provide information to help guide treatments more effectively with regard to timing, depth, duration, and effective management of side-effects. In particular, the rate of rewarming seems to be an important factor in establishing successful use of hypothermia in the treatment of neurological injuries.

Occurrence and outcome of fever in critically ill adults

OBJECTIVE

Although fever is common in the critically ill, only a small number of studies have specifically investigated its epidemiology in the intensive care unit (ICU). The objective of this study was to describe the occurrence of fever in the critically ill and assess its effect on ICU outcome.

DESIGN

Retrospective cohort. Fever was defined by temperature > or = 38.3 degrees C and high fever by > or = 39.5 degrees C.

SETTING

Calgary Health Region during 2000-2006.

PATIENTS

All adults (> or = 18 yrs) admitted to ICUs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 24,204 ICU admission episodes occurred among 20,466 patients; 35% were classified as medical, 33% as cardiac surgical, 16% as other surgical, and 15% as trauma/neurologic. The cumulative incidence of fever and high fever was 44% and 8% and the incidence density was 24.3 and 2.7 per 100 days of ICU admission, respectively. The incidence density of fever was higher in trauma/neuro patients, males, younger patients, and was lower in those with admission Acute Physiology and Chronic Health Evaluation II scores > or = 25. Seventeen percent and 31% of patients with fever and high fever had associated positive cultures. Resolution of fever and high fever occurred in 27% and 53% of patients before ICU discharge and prolonged fever and high fever lasting for 5 or more days in the ICU occurred in 18% and 11% of febrile patients, respectively. Although the presence of fever was not associated with increased ICU mortality (13% vs. 12%; p = .08), high fever was associated with significantly increased risk for death (20.3% vs. 12%, p < .0001). After controlling for confounding factors using multivariable logistic regression models, the influence of fever on the ICU mortality varied significantly according to its timing of onset, degree, and main admission category.

CONCLUSIONS

Fever is common in patients admitted to the ICU and its occurrence and impact on outcome varies among defined patient populations.

Hyperthermia as an early sign of intracranial hemorrhage in full-term neonates

BACKGROUND

Intracranial hemorrhage (ICH) in full-term infants is uncommon and is a rare cause of neonatal fever. This study was conducted to estimate the incidences of ICH and fever in a hospital-based population, and to determine if the clinical features of neonatal ICH with and without hyperthermia differ.

METHODS

We selected 315 afebrile neonates who received cranial ultrasonography screening from 2003 to 2004 as the control group, and 153 neonates diagnosed with fever from 1998 to 2004 as the study group. During the same period, 28 full-term neonates with birth weights >2500g and ICH in the first week of life were enrolled retrospectively. They were divided into hyperthermia (n=11) and nonhyperthermia (n=17) groups.

RESULTS

Three babies in the control group and 11 in the study group had ICH; the incidence of ICH in the hyperthermia group was significantly higher (3/315 vs. 11/153; p < 0.001). Compared with the nonhyperthermia group, the hyperthermia group had Less cyanosis (2/11 vs. 10/17; p = 0.04), Less lymphocyte predominance (33.7 vs. 80%; p = 0.032), higher neutrophil/lymphocyte ratio (1.9 vs. 0.3; p = 0.006), higher erythrocyte/leukocyte ratio (425 vs. 79.5; p = 0.05) in cerebrospinal fluid and an increased incidence of subarachnoid hemorrhage accompanied by intracerebral parenchymal hemorrhage (4/11 vs. 0/17; p = 0.016).

CONCLUSION

The incidence of ICH was higher in febrile than in afebrile neonates. ICH presenting with hyperthermia might go unrecognized, because its other symptoms are subtle and a neutrophil predominance in the cerebrospinal fluid might result in a misdiagnosis of meningitis. ICH in the interior brain tended to manifest more commonly as hyperthermia than did ICH in the superficial brain. A cranial image examination should be considered in the evaluation of neonatal fever.

Use of induced hypothermia for neuroprotection: indications and application

Therapeutic temperature regulation has become an exciting field of interest. Mild-to-moderate hypothermia is a safe and feasible management strategy for neuroprotection and control of intracranial pressure in neurological catastrophies such as traumatic brain injury, subarachnoid and intracerebral hemorrhage, and large hemispheric stroke. Fever is associated with worse neurological outcome in patients with brain injury, normothermia may be of benefit in this patient population. The efficacy of mild-to-moderate hypothermia has been proven for neuroprotection after cardiac arrest with ventricular fibrillation as initial rhythm, and after neonatal asphyxia. Application of hypothermia and fever control in neurocritical care, available cooling technologies and systemic effects and complications of hypothermia will be discussed.

Continuous low dose diclofenac sodium infusion to control fever in neurosurgical critical care

INTRODUCTION

Aim of this randomized prospective clinical trial is to compare two methods of antipyretics and evaluate their efficacy in controlling fever during the acute phase of brain damage.

METHODS

Twenty-two febrile comatose patients: 12 severe traumatic brain injury and 10 subarachnoid hemorrhage divided in 2 groups: Diclofenac low-dose infusion (10 patients) and extemporaneous boluses of NSAIDs (CTRL, 12 patients). The primary outcome measure was length of time with temperature>38 degrees C. Secondary outcome measures were: 1) to assess the effects of each antipyretic strategy on intracranial pressure (ICP), cerebral perfusion pressure (CPP), mean arterial pressure (MAP) and heart rate; 2) to monitor adverse effects of each antipyretic strategy. The baseline characteristics in the two treatment groups were similar.

RESULTS

Primary findings: percentage of time per patient with temperature>38 degrees C was significantly lower (P<0.0001) in the DCF group, 4% (0-22%), vs. 34% (8-56%) in CTRL group. In addition, mean T degrees , max T degrees were lower in DCF than in CTRL (P<0.05). Secondary findings: CPP and MAP were significantly higher in DCF group (P<0.05) while ICP was not different (NS). However, if ICP pre randomization was <25 mmHg, CTRL suffered a worst ICP (24+/-11 vs. 16+/-7 P=0.01), MAP (89+/-10 vs. 104+/-10 P=0.01) and CPP (75+/-10 vs. 94+/-17 P=0.01) compared to DCF. No differences between the two treatment were recorded when ICP>or=25 mmHg before randomization. There was no gastrointestinal or intracranial bleeding.

CONCLUSIONS

Low dose DCF infusion is a potential useful strategy for a successful control temperature better than intermittent NSAIDs dosing, minimizing potentially brain-damaging effects of fever.

Non-infectious fever in the neurological intensive care unit: incidence, causes and predictors

BACKGROUND AND OBJECTIVE

Non-infectious causes of fever are often considered in critical neurological patients but their true significance has not been formally studied. The aim of this study was to evaluate the incidence, causes and predictors of fever in patients with acute neurological/neurosurgical disease and no documented infection.

METHODS

Prospective data collection of consecutive patients admitted to the neurological intensive care unit (NICU) of an academic medical centre for more than 48 h was carried out. Fever was defined as body temperature > or = 101 degrees F (38.3 degrees C) documented on at least one measurement for 2 consecutive days. Patients were enrolled only if a diagnostic workup, including cultures of > or = 2 body samples, was performed before antibiotic use. Febrile patients with no proven evidence of infection were considered to have non-infectious fever.

RESULTS

93 patients were included in the final analysis. Fever was non-infectious in 31 patients (33%). There were no differences between the infectious and non-infectious fever groups in terms of age, use and duration of invasive catheters, daily duration of fever and number of days with fever. Documented infections tended to be more common among febrile patients with traumatic brain injury (52% vs 36%; p = 0.06). Non-infectious fever was more frequent among patients with subarachnoid haemorrhage (48% vs 18%; p = 0.01) in whom it was associated with vasospasm (p = 0.03) and symptomatic vasospasm (p = 0.05). Non-infectious fever started earlier (mean 2.6 vs 4 days; p = 0.007) and onset of fever within the first 72 h of admission predicted negative evaluation for infection (p = 0.01). Subarachnoid haemorrhage and fever onset within the first 72 h were independent predictors of non-infectious fever on multivariable analysis.

CONCLUSIONS

Fever in the absence of documented infections occurs commonly in the NICU, especially among patients with subarachnoid haemorrhage and vasospasm. Early onset of fever predicts a non-infectious cause.

The systemic implications of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is analogous to a pathophysiological watershed, disrupting brain integrity and function and precipitating an array of systemic derangements including cardiovascular, respiratory, endocrine, hematological, and immune dysfunction. Extracerebral organ dysfunction is closely linked to the magnitude of the primary neurological insult, suggesting neurogenic, neuroendocrine and neuroimmunomodulatory mechanisms. Systemic organ involvement is associated with increased mortality and neurological impairment, even after adjustment for other outcome predictors such as the severity of the initial neurological injury. This may be a reflection of secondary brain injury precipitated by hypoxemia, circulatory failure, fever, or hyperglycemia, all of which have been linked to adverse clinical outcomes. Interventions to avert or reverse these and other perturbations need to be tested in clinical trials as they represent opportunities to improve survival and neurological recovery in patients with SAH.

Cumulative dose of hypertension predicts outcome in intracranial hemorrhage better than American Heart Association guidelines

BACKGROUND

Hypertension is common after intracranial hemorrhage (ICH) and may be associated with higher mortality and adverse neurologic outcome. The American Heart Association recommends that blood pressure be maintained at a mean arterial pressure (MAP) less than 130 mm Hg to prevent secondary brain injury.

OBJECTIVES

To prospectively evaluate whether a new method of assessing hypertension in ICH more accurately identifies patients at risk for adverse outcomes.

METHODS

The authors prospectively studied all patients presenting to two University of California, San Francisco hospitals with acute ICH from June 1, 2001, to May 31, 2004. Factors related to acute hospitalization were recorded in a database, including all charted vital signs for the first 15 days. Patients were followed up for one year, with their modified Rankin Scale (mRS) score at 12 months as primary outcome. Hypertension dose was determined as the area under the curve between patient MAP and a cut point of 110 mm Hg while in the emergency department (ED). The dose was adjusted for time spent in the ED (dose/time(ed) [d/t(ed)]). Hypertension dose was divided into four categories (none, and progressive tertiles). Multivariate logistic regression was used to calculate the odds ratio for adverse mRS by tertiles of d/t(ed).

RESULTS

A total of 237 subjects with an ED average (+/-SD) length of stay of 3.42 (+/-3.7) hours were enrolled. In a multivariate logistic regression model controlling for the effects of age, volume of hemorrhage, presence of intraventricular hemorrhage, race, and preexisting hypertension, there was a 4.7- and 6.1-fold greater likelihood of an adverse neurologic outcome (by mRS) at one and 12 months, respectively, in the highest d/t(ed) tertile relative to the referent group without hypertension.

CONCLUSIONS

Hypertension after acute ICH is associated with adverse neurologic outcome. The dose of hypertension may more accurately identify patients at risk for adverse outcomes than the American Heart Association guidelines and may lead to better outcomes if treated when identified in this manner.

Predictors and clinical implications of shivering during therapeutic normothermia

BACKGROUND

Shivering during induced normothermia (IN) remains a therapeutic limitation. We investigated potential risk factors and clinical implications of shivering during IN.

METHODS

Post hoc analysis was performed on 24 patients enrolled in a clinical trial of an automated surface cooling system to achieve IN. Hyponatremia was defined as serum levels <136 mmol/L and hypomagnesaemia as levels <1.5 mg/dL. Continuous heat energy transfer (kcal/h) was averaged hourly. Glasgow Coma Scale (GCS) scores were recorded every 2 h. Shivering status was documented hourly. Mixed effects modeling was used to determine clinical measures associated with shivering. Generalized estimating equation (GEE) models were used to compare baseline-adjusted repeated-measures GCS scores.

RESULTS

About of 24 (39%) patients demonstrated shivering. Shivering was associated with men (67% vs. 21%, P = 0.03), hyponatremia (44% vs. 7%, P = 0.03), and hypomagnesaemia (56% vs. 7%, P = 0.02). The average kcal/h (158 +/- 645 kcal/h vs. 493 +/- 645 kcal/h, P = 0.03) was greater in shivering patients. Shivering was positively associated with increases in heart rate (P < 0.001), respiratory rate (P < 0.001), and kcal/h (P < 0.001). Non-shivering patients showed a greater increase from baseline GCS (GEE, P = 0.02) at 24 h. No differences in sedative doses or fever burden were noted between shiverers and non-shiverers.

CONCLUSIONS

Men, hyponatremia, and hypomagnesaemia may predispose febrile patients treated with IN to shivering. Shivering dramatically increases the amount of heat transfer required to maintain normothermia, and may be associated with adverse effects on level of consciousness.

Effectiveness of an intravascular cooling method compared with a conventional cooling technique in neurologic patients

Fever is common among neurologic patients and is usually treated by antipyretic drugs and external cooling. An alternative method for temperature management may be an intravascular approach. The aim of the study was to compare the effectiveness and the therapeutic costs of this new method with conventional treatment in neurologic patients. Twenty-six patients who suffered from subarachnoid hemorrhage or traumatic brain injury with febrile episodes were included the study and were randomized into 2 different groups. In the "Conventional" group, fever was treated with antipyretic drugs and/or surface cooling techniques to achieve a body core temperature of 36.5 degrees C. In the "CoolGard" group, patients were treated with an intravascular cooling catheter (Coolgard, Alsius, CA). We compared the effectiveness of these 2 approaches by calculating the mean deviation from 36.5 degrees C during a 48-hour period (fever burden). We found a significant difference in the fever burden [CoolGard: -0.49 to 1.22 (median -0.06) degrees C vs. Conventional: 1.05-2.34 (median 1.41) degrees C, P<0.05]. Costs varied significantly between the CoolGard and the Conventional groups, with markedly higher daily costs in the CoolGard group [CoolGard: 15 to 140 US dollars (USD) (median 39 USD) vs. Conventional: 1 to 9 USD (median 5 USD), P<0.05]. The effectiveness of the intravascular cooling catheter is excellent compared with conventional cooling therapies.

Medical management of cerebral edema

✓Cerebral edema is frequently encountered in clinical practice in critically ill patients with acute brain injury from diverse origins and is a major cause of increased morbidity and death in this subset of patients. The consequences of cerebral edema can be lethal and include cerebral ischemia from compromised regional or global cerebral blood flow (CBF) and intracranial compartmental shifts due to intracranial pressure gradients that result in compression of vital brain structures. The overall goal of medical management of cerebral edema is to maintain regional and global CBF to meet the metabolic requirements of the brain and prevent secondary neuronal injury from cerebral ischemia. Medical management of cerebral edema involves using a systematic and algorithmic approach, from general measures (optimal head and neck positioning for facilitating intracranial venous outflow, avoidance of dehydration and systemic hypotension, and maintenance of normothermia) to specific therapeutic interventions (controlled hyperventilation, administration of corticosteroids and diuretics, osmotherapy, and pharmacological cerebral metabolic suppression). This article reviews and highlights the medical management of cerebral edema based on pathophysiological principles in acute brain injury.

Increased Risk of Deep Venous Thrombosis with Endovascular Cooling in Patients with Traumatic Head Injury

Endovascular therapeutic hypothermia has been shown to preserve neurological function and improve outcomes; however, its use and potential complications have not been fully described in patients with traumatic head injuries. We believe that the use of endovascular cooling leads to deep venous thrombosis (DVT) in this high-risk population. We performed a retrospective review of 11 patients with severe head injuries admitted to our Level I trauma center surgical intensive care unit who underwent intravascular cooling. Duplex sonograms were obtained after 4 days at catheter removal or with clinical symptoms that were suspicious for DVT. Patients had a mean age of 23.2 (range, 16–42) years and an Injury Severity Score of 31.9 (range, 25–43). The overall incidence of DVT was 50 per cent. The DVT rate was 33 per cent if catheters were removed in 4 days or less and 75 per cent if removed after 4 days (risk ratio = 2.25; odds ratio = 6; P = ns). An elevated international normalized ratio upon admission was protective against DVT (no DVT = 1.26 vs DVT = 1.09; P = 0.02). Inferior vena cava filters were placed in most patients with DVT. The use of endovascular cooling catheters is associated with increased risk of DVT in patients with traumatic head injuries. Therefore, we discourage the use of endovascular cooling devices in this patient population.

Synergistic effects of ethanol and hyperthermia on carotid artery vasoconstriction

BACKGROUND

Heatstroke is a serious condition and clinical studies indicate that vascular stroke increases with excessive consumption of alcohol (ethanol). It was our objective to test the influence of ethanol on cerebral perfusion at normal and higher temperatures.

METHODS

Recording of isometric tension in rabbit carotid artery strips in organ baths with different concentrations of ethanol at 37 degrees C and during hyperthermia (39-43 degrees C) and scintigraphic cerebral imaging of a radioactive isotope in the control situation and during hyperthermia.

RESULTS

Stepwise heating induced reproducible reversible graded contraction, proportional to temperature. At high concentrations (toxic levels), ethanol induced an increase in tension and heating potentiated these responses. Extracellular Mg(2+) potentiated both heat-induced contraction and ethanol-induced contraction while extracellular Ca(2+) had no effect on these responses. During hyperthermia and ethanol scintigraphic isotope uptake was reduced in cortical and cerebellar regions.

CONCLUSIONS

Carotid artery vasomotor tone is temperature dependent and heating induces vasoconstriction. Alcohol (ethanol) at 37 degrees C elicited carotid artery contraction at high concentrations (toxic levels) but at any concentration during elevated temperature (39-43 degrees C). Ethanol potentiated the effect of hyperthermia-induced vasoconstriction and reduced cerebral perfusion as shown by radionuclide imaging. The synergistic effect of ethanol and hyperthermia may induce heat stroke and brain damage.

A study of possible correlation between subarachnoid haemorrhage related vasospasm and the post-bleed blood platelet count chart in a Caucasian population

INTRODUCTION

There has been controversy about the aetiology and pathophysiology of subarachnoid haemorrhage (SAH) related vasospasm. Several pathogenic factors like endothelin and adhesion molecules have been discussed. A recently published study concerning an exclusively Asian population suggested a relationship between SAH related vasospasm and the blood platelet count. The aim of our study was to examine this relationship in a European population.

METHOD

We carefully reviewed 88 patients with aneurysmal SAH (54 females, 34 males; mean age 52.5 years, range from 22 to 78 years) treated in our centre with regard to the occurrence of vasospasm and the blood platelet count in a ten day interval after initial SAH. Symptomatic vasospasm was defined as a focal neurological deficit or deterioration in the level of consciousness with or without confirmation of infarction on a CT scan. Thirty-seven patients (42%) developed clinically relevant vasospasm.

RESULTS

There was no statistically significant correlation between the blood platelet count chart (maximum and minimum values) and vasospasm or clinical outcome; we also found no gender or age-related influence on the above mentioned relationships.

CONCLUSIONS

In our opinion there appears to be a difference between Caucasian and Asian populations regarding the influence of platelets in the pathophysiology of SAH and vasospasm.