Fever in subarachnoid hemorrhage: relationship to vasospasm and outcome

Fever after subarachnoid hemorrhage: risk factors and impact on outcome

OBJECTIVE

To identify risk factors for refractory fever after subarachnoid hemorrhage (SAH), and to determine the impact of temperature elevation on outcome.

METHODS

We studied a consecutive cohort of 353 patients with SAH with a maximum daily temperature (T(max)) recorded on at least 7 days between SAH days 0 and 10. Fever (>38.3 degrees C) was routinely treated with acetaminophen and conventional water-circulating cooling blankets. We calculated daily T(max) above 37.0 degrees C, and defined extreme T(max) as daily excess above 38.3 degrees C. Global outcome at 90 days was evaluated with the modified Rankin Scale (mRS), instrumental activities of daily living (IADLs) with the Lawton scale, and cognitive functioning with the Telephone Interview of Cognitive Status. Mixed-effects models were used to identify predictors of T(max), and logistic regression models to evaluate the impact of T(max) on outcome.

RESULTS

Average daily T(max) was 1.15 degrees C (range 0.04 to 2.74 degrees C). The strongest predictors of fever were poor Hunt-Hess grade and intraventricular hemorrhage (IVH) (both p < 0.001). After controlling for baseline outcome predictors, daily T(max) was associated with an increased risk of death or severe disability (mRS > or = 4, adjusted OR 3.0 per degrees C, 95% CI 1.6 to 5.8), loss of independence in IADLs (OR 2.6, 95% CI 1.2 to 5.6), and cognitive impairment (OR 2.5, 95% CI 1.2 to 5.1, all p < or = 0.02). These associations were even stronger when extreme T(max) was analyzed.

CONCLUSION

Treatment-refractory fever during the first 10 days after subarachnoid hemorrhage (SAH) is predicted by poor clinical grade and intraventricular hemorrhage, and is associated with increased mortality and more functional disability and cognitive impairment among survivors. Clinical trials are needed to evaluate the impact of prophylactic fever control on outcome after SAH.

THREE-DAY PHENYTOIN PROPHYLAXIS IS ADEQUATE AFTER SUBARACHNOID HEMORRHAGE

OBJECTIVE

Phenytoin (PHT) is widely administered after subarachnoid hemorrhage, often for several weeks or months. In addition to known side effects, PHT use has been correlated with cognitive disability and poor outcome. To reduce the rate of PHT complications, we converted from a multi-week prophylactic regimen to a 3-day course of treatment. This study evaluates the changes in seizure rates and adverse events.

METHODS

From July 1998 to June 2002, 453 patients with spontaneous subarachnoid hemorrhage were treated. In the first 9 months, 79 patients were administered PHT until discharged from the hospital, unless a drug reaction occurred first. In the last 39 months, PHT was discontinued 3 days after admission (370 patients), unless there was a history of epilepsy (four patients). This study represents a retrospective analysis of prospectively collected data, with follow-up periods of 3 to 12 months after discharge.

RESULTS

The 3-day PHT regimen produced a statistically significant reduction (P= 0.002) in the rate of PHT complications. In the first period, seven (8.8%) out of 79 patients experienced a hypersensitivity reaction, compared with two (0.5%) out of 370 patients in the second period. The percentage of patients having seizures, both short- and long-term, did not change significantly. In the first period, the seizure rate during hospitalization was 1.3%; in the second period, it was 1.9% (P= 0.603). At an average follow-up period of 6.7 months, three (5.7%) out of 53 survivors in the first period experienced a seizure (including those who had a seizure during hospitalization). In the second period, 12 (4.6%) out of 261 survivors experienced a seizure at an average follow-up period of 5.4 months (P= 0.573).

CONCLUSION

A 3-day regimen of PHT prophylaxis is adequate to prevent seizures in subarachnoid hemorrhage patients. Drug reactions are significantly reduced, but seizure rates do not change. Short-term PHT administration may be a superior treatment paradigm.

Cerebral pathophysiology and clinical neurology of hyperthermia in humans

Deliberate hyperthermia has been used clinically as experimental therapy for neoplastic and infectious diseases. Several case fatalities have occurred with this form of treatment, but most were attributable to systemic complications rather than central nervous system toxicity. Nonetheless, demyelating peripheral neuropathy and neurological symptoms of nausea, delirium, apathy, stupor, and coma have been reported. Temperatures exceeding 40 degrees C cause transient vasoparalysis in humans, resulting in cerebral metabolic uncoupling and loss of pressure-flow autoregulation. These findings may be related to the development of brain edema, intracerebral hemorrhage, and intracranial hypertension observed after prolonged therapeutic hyperthermia. Furthermore, deliberate hyperthermia critically worsens the extent of histopathological damage in animal models of traumatic, ischemic, and hypoxic brain injury. However, it is unknown whether these findings translate to episodes of spontaneous fever in neurologically injured patients. In a clinical setting fever is a strong prognostic marker of a patient's primary degree of neuronal damage, and a causal relation with long-term functional neurological outcome has not been established for most types of brain injury. Furthermore, in the neurosurgical intensive-care unit fever is extremely common whereas antipyretic therapy is only poorly effective. Therefore maintaining strict normothermia may be an impossible goal in many patients. Although there are several physiological arguments for avoiding exogenous hyperthermia in neurologically injured patients, there is no evidence that aggressive attempts at controlling spontaneous fever can improve clinical outcome.

Hyperthermia and central nervous system injury

Fever is a common occurrence in patients following brain and spinal cord injury (SCI). In intensive care units, large numbers of patients demonstrate febrile periods during the first several days after injury. Over the last several years, experimental studies have reported the detrimental effects of fever in various models of central nervous system (CNS) injury. Small elevations in temperature during or following an insult have been shown to worsen histopathological and behavioral outcome. Thus, the control of fever after brain or SCI may improve outcome if more effective strategies for monitoring and treating hyperthermia were developed. Because of the clinical importance of fever as a potential secondary injury mechanism, mechanisms underlying the detrimental effects of mild hyperthermia after injury have been evaluated. To this end, studies have shown that mild hyperthermia (>37 degrees C) can aggravate multiple pathomechanisms, including excitotoxicity, free radical generation, inflammation, apoptosis, and genetic responses to injury. Recent data indicate that gender differences also play a role in the consequences of secondary hyperthermia in animal models of brain injury. The observation that dissociations between brain and body temperature often occur in head-injured patients has again emphasized the importance of controlling temperature fluctuations after injury. Thus, increased emphasis on the ability to monitor CNS temperature and prevent periods of fever has gained increased attention in the clinical literature. Cooling blankets, body vests, and endovascular catheters have been shown to prevent elevations in body temperature in some patient populations. This chapter will summarize evidence regarding hyperthermia and CNS injury.

Therapeutic temperature modulation in neurocritical care

The ability to effectively achieve and maintain long-term temperature control is an important goal that has been previously unachievable in the neurocritical care setting. Previous attempts have been limited by the inability to overcome physiologic defense mechanisms, short duration of action, or significant adverse effects. Recent advances in technology have made therapeutic temperature modulation feasible. In this review, current concepts of therapeutic temperature modulation are presented. New advances in technology may provide an important breakthrough in the ability to reduce fever-associated morbidity in neurocritically ill patients. What remains to be seen is whether the advantages of these technologies will outweigh the risks associated with therapeutic temperature modulation.

Medical complications after subarachnoid hemorrhage: new strategies for prevention and management

PURPOSE OF REVIEW

To summarize new concepts regarding the occurrence, prevention, and management of medical complications following subarachnoid hemorrhage.

RECENT FINDINGS

Data regarding the impact of common medical complications after subarachnoid hemorrhage on delayed cerebral ischemia and neurological outcome after subarachnoid hemorrhage are available from recent outcomes studies. Fever, anemia requiring transfusion, hyperglycemia, electrolyte abnormalities, pneumonia, hypertension, and neurogenic stunned myocardium and pulmonary edema occur frequently after subarachnoid hemorrhage. Fever, anemia, hyperglycemia, and acute hypoxia and hypotension related to neurogenic stunned myocardium have the greatest impact on mortality and functional outcome after subarachnoid hemorrhage. Potential treatment interventions for these complications include the development of acute resuscitation strategies to optimize cerebral perfusion in poor-grade patients, maintaining normothermia with systemic cooling devices, administration of erythropoietin to prevent severe anemia, preserving normoglycemia with continuous insulin infusions, and goal-directed hemodynamic support guided by brain tissue oxygenation.

SUMMARY

Clinical trials to investigate interventions targeted at preventing or treating common medical complications after subarachnoid hemorrhage are needed.

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 trails of induced hypothermia in patients with acute neurologic insults and describes methods of fever control.

The simplified acute physiology score to predict outcome in patients with subarachnoid hemorrhage

OBJECTIVE

Current prognosticators for patients with subarachnoid hemorrhage (SAH) do not take into account signs of extracerebral organ dysfunction. This may explain the only moderate predictive value of these prognosticators. We assessed the prognostic value of the simplified acute physiology score (SAPS) II in SAH patients.

METHODS

In a retrospective cohort study of 148 consecutive SAH patients, we related the SAPS II calculated within 24 hours after admission to clinical and initial computed tomographic imaging characteristics using the Mann-Whitney U test. We compared the prognostic value of the SAPS II with that of the World Federation of Neurosurgical Surgeons score, the patient's age, and the amount of blood showing in computed tomographic imaging for the occurrence of delayed cerebral ischemia using Cox proportional hazards modeling or, for poor outcome (death or dependence), logistic regression modeling.

RESULTS

In the univariate analysis, the SAPS II was the strongest prognosticator; in the multivariate model, the SAPS II was the only independent predictor for outcome (odds ratio, 1.08; 95% confidence interval, 1.06-1.11]). Patients in the highest tertile of SAPS II had a significantly higher risk of poor outcome than those in the lowest tertile (odds ratio, 30.9; 95% confidence interval, 9.9-96.7]). The SAPS II was also the only independent predictor for the occurrence of delayed cerebral ischemia (hazard ratio, 1.020; 95% confidence interval, 1.002-1.039]).

CONCLUSION

The SAPS II is a useful and reliable prognosticator in SAH patients. This score may provide more information than specific SAH scales in predicting poor outcome or the occurrence of delayed cerebral ischemia in some circumstances.

Impact of medical complications on outcome after subarachnoid hemorrhage

OBJECTIVE

Medical complications occur frequently after subarachnoid hemorrhage (SAH). Their impact on outcome remains poorly defined.

DESIGN

Inception cohort study.

PATIENTS

Five-hundred eighty patients enrolled in the Columbia University SAH Outcomes Project between July 1996 and May 2002.

SETTING

Neurologic intensive care unit.

INTERVENTIONS

Patients were treated according to standard management protocols.

MEASUREMENTS AND MAIN RESULTS

Poor outcome was defined as death or severe disability (modified Rankin score, 4-6) at 3 months. We calculated the frequency of medical complications according to prespecified criteria and evaluated their impact on outcome, using forward stepwise multiple logistic regression after adjusting for known predictors of poor outcome. Thirty-eight% had a poor outcome; mortality was 21%. The most frequent complications were temperature>38.3 degreesC (54%), followed by anemia treated with transfusion (36%), hyperglycemia>11.1 mmol/L (30%), treated hypertension (>160 mm Hg systolic; 27%), hypernatremia>150 mmol/L (22%), pneumonia (20%), hypotension (<90 mm Hg systolic) treated with vasopressors (18%), pulmonary edema (14%), and hyponatremia<130 mmol/L (14%). Fever (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.1-3.4; p=.02), anemia (OR, 1.8; 95% CI, 1.1-2.9; p=.02), and hyperglycemia (OR, 1.8; 95% CI, 1.1-3.0; p=.02) significantly predicted poor outcome after adjustment for age, Hunt-Hess grade, aneurysm size, rebleeding, and cerebral infarction due to vasospasm.

CONCLUSIONS

Fever, anemia, and hyperglycemia affect 30% to 54% of patients with SAH and are significantly associated with mortality and poor functional outcome. Critical care strategies directed at maintaining normothermia, normoglycemia, and prevention of anemia may improve outcome after SAH.

Extracerebral organ dysfunction in the acute stage after aneurysmal subarachnoid hemorrhage

In patients with aneurysmal subarachnoid hemorrhage (SAH), secondary complications are an important cause of morbidity and case fatality. Delayed cerebral ischemia and hydrocephalus are important intracranial secondary complications. Potentially treatable extracranial complications are also frequently observed, and some are related to the occurrence of delayed cerebral ischemia and outcome. In addition to the occurrence of an inflammatory response and metabolic derangements, cardiac and pulmonary complications are the most common extracranial complications. This article provides an overview of the most common extracranial complications in patients with SAH and describes their effects on outcome and delayed cerebral ischemia.

Gender and family composition related to discharge destination and length of hospital stay after acute stroke

Informal care by family members still plays an important role in home care after acute stroke. This study determined the clinical and demographic factors, such as family structure, that predict discharge to home and length of hospital stay (LOS) after acute stroke hospitalization. We reviewed the sex, age, family structure before stroke, type of stroke, size of the lesion, activities of daily living (ADL) function at discharge, discharge destination, and LOS of stroke patients (114 cerebral infarctions and 44 intracerebral hemorrhages) admitted to a neurosurgical hospital. Patients with cerebral infarction were older than those with intracerebral hemorrhage (median 75 vs 66 years). Ninety-eight were discharged to home (62%). In the logistic regression analysis, low ADL function, medium or large infarction, and intracerebral hemorrhage (vs lacunar infarction) were significantly associated with discharge to a destination other than home. Of the patients discharged home, low ADL function was strongly associated with LOS in the multiple regression analysis. In addition, living with a spouse only had the opposite effect on LOS in men and women (p=0.050 and 0.071, respectively). LOS tended to be shorter for men with a wife, but longer for women with a husband. The structure and gender roles in a stroke patient's household may need further attention for the efficient use of hospital resources.

Fatores preditivos do prognóstico em vítimas de trauma craniencefálico

OBJETIVO: Definir os fatores preditivos de morbidade (seqüelas neurológicas) e letalidade, em vítimas de trauma craniencefálico. MÉTODO: Revisão consecutiva de 555 prontuários médicos de vítimas de trauma craniencefálico, internadas no ano de 2001, no Hospital Geral do Estado da Bahia. RESULTADOS: Verificaram-se taxas de morbidade de 19,6% e letalidade de 22,9%, com maior número de óbitos em homens a partir da terceira década de vida; os acidentes com meios de transporte foram responsáveis por 64 (50,4%) óbitos. Na análise multivariada, foram preditivos de letalidade a faixa etária a partir da terceira década, vítimas de acidentes com meios de transporte e a presença de febre. Febre foi o único fator preditivo de morbidade. CONCLUSÃO: Febre é um fator de risco independente e modificável de morbiletalidade no trauma craniencefálico.

The Effect of Hypothermia and Hyperthermia on Acute Brain Injury

The brain is extraordinarily susceptible to changes in temperature. Hyperthermia has been shown to exacerbate the biochemical cascade of secondary brain injury. Inversely, hypothermia limits the damaging effects of secondary brain injury. There has been a great deal of investigation regarding the detrimental effects of hyperthermia and the neuroprotection of hypothermia in animal studies. Within the last decade, clinical trials have begun to establish how the brain reacts to both temperature extremes. In the future, studies of hypothermia will continue in the quest of the optimal timing and degree of hypothermia. Hyperthermia will be examined in depth for its detrimental effects on an injured brain. Interventions for the prevention and treatment of hyperthermia will be explored. Nurses will implement cooling strategies to induce hypothermia, applying interventions to prevent complications, and they will also diagnose hyperthermia, deciding when and if to intervene pharmacologically and therapeutically. These advanced nursing actions will be guided by knowledge and understanding of available evidence. This article presents the pathophysiology of secondary brain injury and how it is affected by both hypothermia and hyperthermia. A review of the research leading up to clinical trials is explored, as well as a discussion of the future of temperature modulation for the brain injury patient. This information will help healthcare providers understand the effect that both hypothermia and hyperthermia have on the acutely injured brain.

Relationship between hyperglycemia and symptomatic vasospasm after subarachnoid hemorrhage*

OBJECTIVE

To determine the relationship between blood glucose levels (mg/dL) and occurrence of symptomatic vasospasm (VSP) and clinical outcomes after aneurysmal subarachnoid hemorrhage.

DESIGN

Retrospective observational study of 352 patients with subarachnoid hemorrhage admitted within 48 hrs of ictus between January 1995 and June 2002.

SETTING

Neurointensive care unit.

PATIENTS

Adult patients admitted after subarachnoid hemorrhage.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Variables included age; Hunt-Hess classification score; Fisher group; insulin use; infectious disease status; history of diabetes mellitus; and blood glucose values. Poor clinical outcome was defined by a modified Rankin score > or =3, and hyperglycemia was defined by a blood glucose level >140 mg/dL. Mean daily blood glucose values were assessed from admission to development of VSP or day 14. Mean admission blood glucose value, mean inpatient blood glucose value, insulin use, infectious disease status, Hunt-Hess classification score, Fisher group, and history of diabetes mellitus were entered in a Cox proportional hazards model. VSP occurred in 103 (29.2%) of 352 patients. Mean admission blood glucose values (176.6 +/- 40.3 mg/dL vs. 162.3 +/- 47.8 mg/dL; p = .01) and mean inpatient blood glucose values (166.2 +/- 24.7 mg/dL vs. 155.8 +/- 29.7 mg/dL; p = .001) were significantly higher in patients with VSP. Mean inpatient blood glucose value (relative risk, 1.01; 95% confidence interval, 1.0-1.03; p = .04), Hunt-Hess classification score > or =3 (relative risk, 2.23; 95% confidence interval, 1.21-3.99; p = .02), and Fisher group score of 3 (relative risk, 1.28; 95% confidence interval, 1.15-3.1; p = .05) increased the risk for VSP. Hyperglycemia was associated with longer length of stay in the neurointensive care unit (14.5 +/- 7.1 days vs. 11.6 +/- 5.4 days; p < .001) and poor outcome at discharge (modified Rankin score > or =3: 58.9% vs. 18.8%; p < .001).

CONCLUSIONS

Mean inpatient blood glucose value is associated with the development of VSP and may represent a target for therapy to prevent VSP and improve clinical outcomes.

[Controlled mild-to-moderate hypothermia in the intensive care unit]

Controlled hypothermia is used as a therapeutic intervention to provide neuroprotection and (more recently) cardioprotection. The growing insight into the underlying pathophysiology of apoptosis and destructive processes at the cellular level, and the mechanisms underlying the protective effects of hypothermia, have led to improved application and to a widening of the range of potential indications. In many centres hypothermia has now become part of the standard therapy for post-anoxic coma in certain patients, but for other indications its use still remains controversial. The negative findings of some studies may be partly explained by inadequate protocols for the application of hypothermia and insufficient attention to the prevention of potential side effects. This review deals with some of the concepts underlying hypothermia-associated neuroprotection and cardioprotection, and discusses some potential clinical indications as well as reasons why some clinical trials may have produced conflicting results. Practical aspects such as methods to induce hypothermia, as well as the side effects of cooling are also discussed.

Decrease in platelet count as an independent risk factor for symptomatic vasospasm following aneurysmal subarachnoid hemorrhage

Object. Increased platelet consumption is expected in patients with cerebral vasospasm, according to data from clinical and experimental studies. The authors investigated sequential changes in platelet counts in patients with subarachnoid hemorrhage (SAH) and the difference in platelet consumption between patients with and those without symptomatic vasospasm (SV). Variables related to platelet count as well as other clinical and radiological variables were analyzed as independent predictors of SV.

Methods. One hundred consecutive patients who had undergone surgery within 48 hours after SAH onset were entered in the study. Clinical and radiological variables and blood cell counts, including red blood cells, white blood cells, and platelets, after SAH were retrospectively examined. Twenty of these variables were entered into univariate and multivariate analyses to determine predictors for SV.

After SAH, the platelet count decreased to a minimum and then increased rapidly to levels greater than those recorded on admission. This change was specific to SAH, and platelet consumption was more severe in patients with SV than in those without. There were three independent predictors of SV: a ratio of the lowest platelet count and the admission count greater than 0.7 (odds ratio [OR] 0.322, 95% confidence interval [CI] 0.124–0.834, p = 0.0196) and a history of hypertension (OR 0.338, 95% CI 0.126–0.906, p = 0.0311) were negatively significant (that is, decreases the occurrence of SV), and a Fisher Grade 3 (OR 4.42, 95% CI 1.48–13.2, p = 0.0077) was positively significant (that is, increases the occurrence of SV).

Conclusions. The association between a decrease in platelet count and the occurrence of SV indicates the important role of platelets in the pathophysiology of vasospasm following SAH.

Influence of data resolution and interpolation method on assessment of secondary brain insults in neurocritical care

Continuous monitoring of physiologic vital signs is routine in neurocritical care. However, this patient information is usually only recorded intermittently (most often hourly) in the medical record. It is unclear whether this is sufficient to represent the occurrence of secondary brain insults (SBIs) or whether more frequent data collection will provide more comprehensive information for patient care. In 16 patients, physiologic data were acquired concurrently via two methods: per clinical routine, usually hourly, in the medical record (MR) and every minute via a custom data acquisition system (DA). SBIs were defined as a mean arterial pressure<90 mmHg, an intracranial pressure>20 mmHg or a temperature>37.5 degrees C. Number of events, cumulative duration of events and area under the curve (AUC) were compared between the two methods and 95% limits of agreement were assessed for various methods of MR data interpolation. For all three parameters, analysis of the DA and MR data frequently differed with regard to number of events, total duration of events and AUC. MR data tended to underestimate the number of total events. 95% limits of agreement were most narrow for trapezoidal interpolation of MR data, but even these limits were fairly broad. Assessment of secondary brain insults is highly dependent on (1) the temporal resolution of the method used to acquire patient data and on (2) the interpolation method if data are acquired intermittently. High frequency data acquisition may be necessary for more precise evaluation of secondary brain injury in neurocritical care.

Clinical trial of a novel surface cooling system for fever control in neurocritical care patients

OBJECTIVE

To compare the efficacy of a novel water-circulating surface cooling system with conventional measures for treating fever in neuro-intensive care unit patients.

DESIGN

Prospective, unblinded, randomized controlled trial.

SETTING

Neurologic intensive care unit in an urban teaching hospital.

PATIENTS

Forty-seven patients, the majority of whom were mechanically ventilated and sedated, with fever > or =38.3 degrees C for >2 consecutive hours after receiving 650 mg of acetaminophen.

INTERVENTIONS

Subjects were randomly assigned to 24 hrs of treatment with a conventional water-circulating cooling blanket placed over the patient (Cincinnati SubZero, Cincinnati OH) or the Arctic Sun Temperature Management System (Medivance, Louisville CO), which employs hydrogel-coated water-circulating energy transfer pads applied directly to the trunk and thighs.

MEASUREMENTS AND MAIN RESULTS

Diagnoses included subarachnoid hemorrhage (60%), cerebral infarction (23%), intracerebral hemorrhage (11%), and traumatic brain injury (4%). The groups were matched in terms of baseline variables, although mean temperature was slightly higher at baseline in the Arctic Sun group (38.8 vs. 38.3 degrees C, p = .046). Compared with patients treated with the SubZero blanket (n = 24), Arctic Sun-treated patients (n = 23) experienced a 75% reduction in fever burden (median 4.1 vs. 16.1 C degrees -hrs, p = .001). Arctic Sun-treated patients also spent less percent time febrile (T > or =38.3 degrees C, 8% vs. 42%, p < .001), spent more percent time normothermic (T < or =37.2 degrees C, 59% vs. 3%, p < .001), and attained normothermia faster than the SubZero group median (2.4 vs. 8.9 hrs, p = .008). Shivering occurred more frequently in the Arctic Sun group (39% vs. 8%, p = .013).

CONCLUSION

The Arctic Sun Temperature Management System is superior to conventional cooling-blanket therapy for controlling fever in critically ill neurologic patients.

Length of stay and mortality in neurocritically ill patients: impact of a specialized neurocritical care team

OBJECTIVE

To determine predictors of in-hospital and long-term mortality and length of stay in patients admitted to the neurosciences critical care unit.

DESIGN

Retrospective analysis of a prospectively collected database.

SETTING

Neurosciences critical care unit of a large academic tertiary care hospital.

PATIENTS

Adult patients (n = 2381) admitted to our neurosciences critical care unit from January 1997 to April 2000.

INTERVENTIONS

Introduction of a specialized neurocritical care team.

MEASUREMENTS AND MAIN RESULTS

Data obtained from the database included demographics, admission source, length of stay, neurosciences critical care unit and hospital disposition, admission Acute Physiology and Chronic Health Evaluation (APACHE) III score, and principal and secondary diagnoses. The introduction of a neurocritical care team in September 1998 was also collected, as was death at 1 yr after admission. Univariate analysis was carried out using Student's t-test, Mann-Whitney U test, or chi-square test (significance, p < .05). A logistic regression model was used to create a prediction model for in-hospital and long-term mortality. A general linear model was used to determine predictors of length of stay (after log transformation). Independent predictors of in-hospital mortality included APACHE III (odds ratio, 1.07 [1.06-1.08]) and admission from another intensive care unit (odds ratio, 2.9 [1.4-6.2]). The presence of a neurocritical care team was an independent predictor of decreased mortality (odds ratio, 0.7 [0.5-1.0], p = .044). Admission after the neurocritical care team was implemented was associated with reduced length of stay in both the neurosciences critical care unit (4.2 +/- 4.0 vs. 3.7 +/- 3.4, p < .001) and the hospital (9.9 +/- 8.0 vs. 8.4 +/- 6.9, p < .0001). There was no difference in readmission rates to the intensive care unit or discharge disposition to home before and after the neurocritical care team was established. The availability of the neurocritical care team was not associated with significant changes in long-term mortality. Factors independently associated with long-term mortality included female gender, admission from another intensive care unit, APACHE III score, and being moderately disabled before admission.

CONCLUSION

Introduction of a neurocritical care team, including a full-time neurointensivist who coordinated care, was associated with significantly reduced in-hospital mortality and length of stay without changes in readmission rates or long-term mortality.

Elevated body temperature independently contributes to increased length of stay in neurologic intensive care unit patients

OBJECTIVE

Elevated temperature results in worse outcome in experimental models of cerebral ischemia and brain trauma. In critically ill neurologic and neurosurgical patients, elevated body temperature is common and is associated with neurologic deterioration and poor outcome. We sought to determine whether, after controlling for age, severity of illness, and complications, elevated body temperature remained an important predictor of intensive care unit (ICU) and hospital length of stay, mortality rate, and hospital disposition in a large cohort of patients emergently admitted to a neurologic ICU.

DESIGN

Prospectively collected data (demographics, diagnosis, Acute Physiology and Chronic Health Evaluation II score, Glasgow Coma Scale score, daily maximum temperature, complications, disposition) were retrospectively reviewed.

SETTING

A 20-bed neurology/neurosurgery ICU in a tertiary care academic, level I trauma, referral center.

SUBJECTS

From 6,759 admissions, those admitted after an elective procedure with length of stay < or = 1 day, those <18 yrs old, and those with incomplete data were excluded, leaving 4,295 patients for this analysis. First, a hierarchical multiple regression analysis was performed to determine whether elevated body temperature was an independent predictor of length of stay. Second, a path analysis was performed to define the relationships among elevated body temperature, complications, and length of stay. Finally, a matched, weighted sample was developed to quantify the difference in length of stay.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We measured ICU and hospital length of stay, mortality rate, and discharge disposition. The presence of elevated body temperature was associated with a dose-dependent longer ICU and hospital length of stay, higher mortality rate, and worse hospital disposition. The most important predictor of ICU length of stay was the number of complications (beta =.681) followed by elevated body temperature (beta =.143). In the matched, weighted population, the presence of elevated body temperature was associated with 3.2 additional ICU days and 4.3 additional hospital days.

CONCLUSION

In a large cohort of neurologic ICU patients, after we controlled for severity of illness, diagnosis, age, and complications, elevated body temperature was independently associated with a longer ICU and hospital length of stay, higher mortality rate, and worse outcome.

Effect of acute physiologic derangements on outcome after subarachnoid hemorrhage

OBJECTIVE

To determine the effect that acute physiologic derangements have on outcome after subarachnoid hemorrhage (SAH) and to design a composite score summarizing these abnormalities.

DESIGN

Prospective observational study.

SETTING

Neuroscience intensive care unit in a tertiary care academic center.

PATIENTS

Consecutive cohort of 413 patients with SAH admitted within 3 days of SAH onset with 3-month modified Rankin Scale scores.

INTERVENTIONS

None.

RESULTS

Among 20 physiologic variables assessed within 24 hrs of admission, four were independently associated with death or severe disability (modified Rankin Scale score, 4-6) at 3 months in a multivariate analysis: arterio-alveolar gradient of >125 mm Hg (odds ratio [OR], 4.5; 95% confidence interval [CI], 2.7-7.6), serum bicarbonate of <20 mmol/L (OR, 2.9; 95% CI, 1.6-5.6), serum glucose of >180 mg/dL (OR, 2.8; 95% CI, 1.6-4.8), and mean arterial pressure of <70 or >130 mm Hg (OR, 1.7; 95% CI, 1.0-2.9). Based on their proportional contribution to outcome, we constructed the SAH Physiologic Derangement Score (SAH-PDS; range, 0-8) by assigning the following weights for abnormal findings: arterio-alveolar gradient, 3 points; bicarbonate, 2 points; glucose, 2 points; and mean arterial pressure, 1 point. After controlling for known predictors of death or severe disability (age, admission neurologic status, loss of consciousness, aneurysm size, intraventricular hemorrhage, and rebleeding), the SAH Physiologic Derangement Score was independently associated with poor outcome (OR, 1.3 for each point increase; 95% CI, 1.1-1.6). By contrast, the systemic inflammatory response syndrome score and the Acute Physiology and Chronic Health Evaluation II physiologic subscore did not add predictive value to the model.

CONCLUSION

Acute interventions specifically targeting hypoxemia, metabolic acidosis, hyperglycemia, and cardiovascular instability may improve the outcome of SAH patients. The SAH Physiologic Derangement Score may prove useful for rapidly quantifying the severity of important physiologic derangements in acute SAH.

Controlled normothermia in neurologic intensive care

Preclinical studies of cerebral ischemia and trauma find increased brain tissue injury and worsened functional outcomes if the brain temperature exceeds 39 degrees C. Several retrospective studies of patients with new-onset stroke, intracerebral hemorrhage, or subarachnoid hemorrhage support these observations. However, fever is very common among these patients early after the onset of their disease, particularly if they are in the ICU for a week or more, and brain temperatures are likely to be as much as 2 degrees C higher than rectal temperatures. Finally, intravascular temperature modulation has been shown to be more effective for preventing fever than conventional methods, such as antipyretic medications or surface-cooling techniques. Further study is needed to establish if such better control of temperature will lead to improved outcomes.

Severe traumatic head injury in adults: which patients are at risk of early hyperthermia?

OBJECTIVE

Prevention of secondary insults, such as hyperthermia, is a major goal after traumatic brain injury. The aim of our study was to identify risk factors for early hyperthermia in severe head-injured patients.

DESIGN

Retrospective cohort study.

SETTING

A 17-bed multidisciplinary ICU of a 700-bed teaching hospital.

PATIENTS

A total of 101 adult patients admitted from January 1999 to December 2001 requiring continuous monitoring of intracranial pressure according to international guidelines.

MEASUREMENT AND RESULTS

Forty-four patients experienced early hyperthermia (at least one episode of body temperature >38.5 degrees C within the first 2 days). On univariate analysis five variables were associated with early hyperthermia: sex; body temperature; white blood cell count on admission; prophylactic use of acetaminophen; and diabetes insipidus within 2 days. On multivariate analysis, white blood cell count >14.5 x 10(9)/l on admission (odds ratio, 7.1; 95% confidence interval, 2.4-20.5; p=0.001) and a body temperature on admission >36 degrees C (odds ratio, 6.7; 95% confidence interval, 2.3-20.1) were strong risk factors of early hyperthermia. Prophylactic use of acetaminophen was negatively associated with early hyperthermia (odds ratio, 0.1; 95% confidence interval, 0.02-0.4). Patients who experienced early hyperthermia were less prone to have good recovery (GOS=5; p=0.03). More patients with severe or moderate disability (GOS=3 or 4) experienced early hyperthermia ( p=0.01).

CONCLUSION

We identified a subgroup of patients at high risk of early hyperthermia, which is common in severe head-injured patients. These results could have clinical implications for prevention of hyperthermia after traumatic brain injury in adults.

Treatment of fever in the neurologic intensive care unit with a catheter-based heat exchange system

CONTEXT

Elevated temperature worsens injury in experimental focal and global ischemia and brain trauma. Fever is common in patients with acute neurologic illness and independently predicts poor outcome. Conventional means of treating fever are not very effective in this population.

OBJECTIVE

To study the effectiveness of a catheter-based heat exchange system in reducing elevated temperatures in critically ill neurologic and neurosurgical patients. DESIGN, INTERVENTION, SETTING, AND POPULATION: This was a prospective randomized, non-blinded trial that compared conventional treatment of fever (acetaminophen and cooling blankets) with conventional treatment plus an intravascular catheter-based heat exchange system (Alsius, Irvine, CA). Patients admitted to one of 13 neurologic intensive care units in academic medical centers were eligible if they a) suffered subarachnoid hemorrhage, intracerebral hemorrhage, ischemic infarction, or traumatic brain injury; b) had a temperature >38 degrees C on two occasions or for >4 continuous hrs; and c) required central venous access.

MAIN OUTCOME MEASURE

The fever burden (area under the curve >38 degrees C) for 72 hrs was compared in an intention to treat analysis. Safety of the catheter system was monitored.

RESULTS

A total of 296 patients were enrolled over 20 months. Forty-one percent had subarachnoid hemorrhage, 24% had traumatic brain injury, 23% had intracerebral hemorrhage, and 13% had ischemic stroke. The groups were matched in terms of age, body mass index, sex, and Glasgow Coma Scale score distribution. Fever burden was 7.92 vs. 2.87 degrees C-hrs in the conventional group and catheter groups, respectively (64% reduction, p <.01). There was no higher rate of infection or the use of sedatives, narcotics, or antibiotics in the catheter group. The catheter did not significantly increase risk to the patient beyond that of a central catheter.

CONCLUSIONS

The addition of this catheter-based cooling system to conventional management significantly improves fever reduction in neurologic intensive care unit patients.

Application of therapeutic hypothermia in the ICU: opportunities and pitfalls of a promising treatment modality. Part 1: Indications and evidence

OBJECTIVE

Hypothermia has been used for medicinal purposes since ancient times. This paper reviews the current potential clinical applications for mild hypothermia (32-35 degrees C).

DESIGN AND SETTING

Induced hypothermia is used mostly to prevent or attenuate neurological injury, and has been used to provide neuroprotection in traumatic brain injury, cardiopulmonary resuscitation, stroke, and various other disorders. The evidence for each of these applications is discussed, and the mechanisms underlying potential neuroprotective effects are reviewed. Some of this evidence comes from animal models, and a brief overview of these models and their limitations is included in this review.

RESULTS

The duration of cooling and speed of re-warming appear to be key factors in determining whether hypothermia will be effective in preventing or mitigating neurological injury. Some other potential usages of hypothermia, such as its use in the peri-operative setting and its application to mitigate cardiac injury following ischemia and reperfusion, are also discussed.

CONCLUSIONS

Although induced hypothermia appears to be a highly promising treatment, it should be emphasized that it is associated with a number of potentially serious side effects, which may negate some or all of its potential benefits. Prevention and/or early treatment of these complications are the key to successful use of hypothermia in clinical practice. These side effects, as well as various physiological changes induced by cooling, are discussed in a separate review.

Therapeutic hypothermia

Hypothermia is common during anaesthesia and surgery owing to anaesthetic-induced inhibition of thermoregulatory control. Perioperative hypothermia is associated with numerous complications. However, for certain patient populations, and under specific clinical conditions, hypothermia can provide substantial benefits. Lowering core temperature to 32-34 degrees C may reduce cell injury by suppressing excitotoxins and oxygen radicals, stabilizing cell membranes, and reducing the number of abnormal electrical depolarizations. Evidence from animal studies indicates that even mild hypothermia provides substantial protection against cerebral ischaemia and myocardial infarction. Mild hypothermia has been shown to improve outcome after cardiac arrest in humans. Randomized trials are in progress to evaluate the potential benefits of mild hypothermia during aneurysm clipping and after stroke or acute myocardial infraction. However, as hypothermia can cause unwanted side-effects, further research is needed to better quantify the risks and benefits of therapeutic hypothermia.

Leukocytosis as an independent risk factor for cerebral vasospasm following aneurysmal subarachnoid hemorrhage

OBJECT

The identification of patients at an increased risk for cerebral vasospasm after subarachnoid hemorrhage (SAH) may allow for more aggressive treatment and improved patient outcomes. Note, however, that blood clot size on admission remains the only factor consistently demonstrated to increase the risk of cerebral vasospasm after SAH. The goal of this study was to assess whether clinical, radiographic, or serological variables could be used to identify patients at an increased risk for cerebral vasospasm.

METHODS

A retrospective review was conducted in all patients with aneurysmal or spontaneous nonaneurysmal SAH who were admitted to the authors' institution between 1995 and 2001. Underlying vascular diseases (hypertension or chronic diabetes mellitus), Hunt and Hess and Fisher grades, patient age, aneurysm location, craniotomy compared with endovascular aneurysm stabilization, medications on admission, postoperative steroid agent use, and the occurrence of fever, hydrocephalus, or leukocytosis were assessed as predictors of vasospasm. Two hundred twenty-four patients were treated for SAH during the review period. One hundred one patients (45%) developed symptomatic vasospasm. Peak vasospasm occurred 5.8 +/- 3 days after SAH. There were four independent predictors of vasospasm: Fisher Grade 3 SAH (odds ratio [OR] 7.5, 95% confidence interval [CI] 3.5-15.8), peak serum leukocyte count (OR 1.09, 95% CI 1.02-1.16), rupture of a posterior cerebral artery (PCA) aneurysm (OR 0.05, 95% CI 0.01-0.41), and spontaneous nonaneurysmal SAH (OR 0.14, 95% CI 0.04-0.45). A serum leukocyte count greater than 15 x 10(9)/L was independently associated with a 3.3-fold increase in the likelihood of developing vasospasm (OR 3.33, 95% CI 1.74-6.38).

CONCLUSIONS

During this 7-year period, spontaneous nonaneurysmal SAH and ruptured PCA aneurysms decreased the odds of developing vasospasm sevenfold and 20-fold, respectively. The presence of Fisher Grade 3 SAH on admission or a peak leukocyte count greater than 15 x 10(9)/L increased the odds of vasospasm sevenfold and threefold, respectively. Monitoring of the serum leukocyte count may allow for early diagnosis and treatment of vasospasm.

Natural hypothermia immediately after transient global cerebral ischemia induced by spontaneous subarachnoid hemorrhage

OBJECT

Spontaneous subarachnoid hemorrhage (SAH) has an aspect of graded transient global cerebral ischemia. The purpose of the present study was the documentation of sequential changes in body temperature immediately after SAH-induced transient global cerebral ischemia in humans.

METHODS

Patients admitted within 12 hours after the initial onset of SAH were examined retrospectively (426 patients). Patients with unruptured cerebral aneurysms served as a control group (73 patients). Body temperature measured at the axilla on admission was analyzed. The grade of SAH was established according to the Glasgow Coma Scale (GCS): Grade I, GCS Score 15; Grade II, GCS Score 11 to 14; Grade III, GCS Score 8 to 10; Grade IV, GCS Score 4 to 7; and Grade V, GCS Score 3. The mean body temperature of patients in the control group was 36.49 +/- 0.45 degrees C (mean +/- standard deviation). The mean body temperature of patients in the SAH group who had been admitted within 4 hours of onset for Grades I to V were significantly different (p < 0.001, analysis of variance [ANOVA]): 36.26 +/- 0.7 degrees C, 59 patients; 35.98 +/-0.85 degrees C, 73 patients; 35.52 +/- 0.79 degrees C, 25 patients; 35.9 +/- 1.09 degrees C, 108 patients; and 35.56 +/- 1.14 degrees C, 73 patients, respectively. These values were significantly lower than those in control volunteers, except for patients with Grade I SAH. The reduction in body temperature was unrelated to the location of the cerebral aneurysm and was not the product of circadian rhythm. The temperatures of patients in the SAH group who were admitted beyond 4 hours after onset for each grade were significantly different (p < 0.01, ANOVA): 36.8 +/- 0.91 degrees C, 36 patients; 36.74 +/- 0.68 degrees C, 31 patients; 36.73 +/- 0.38 degrees C, three patients; 37.41 +/- 1.37 degrees C, 17 patients; and 38.9 degrees C, one patient, respectively. These values were significantly higher than those in patients admitted within 4 hours of SAH onset for all grades except Grade V, and significantly higher than control values in patients with Grades I and IV SAH.

CONCLUSIONS

These results indicate that body temperature falls and then rises immediately after the SAH-induced transient global cerebral ischemia without cardiac arrest in humans. The reduction in temperature may be a natural cerebral protection mechanism that is activated shortly after ischemic insult.

Safety and efficacy of a novel intravascular cooling device to control body temperature in neurologic intensive care patients: a prospective pilot study

OBJECTIVE

To determine the safety and efficacy of a novel intravascular cooling device (Cool Line catheter with Cool Gard system) to control body temperature (temperature goal <37 degrees C) in neurologic intensive care patients.

DESIGN

A prospective, uncontrolled pilot study in 51 consecutive neurologic intensive care patients.

SETTING

A neurologic intensive care unit at a tertiary care university hospital.

PARTICIPANTS

Patients were 51 neurologic intensive care patients with an intracranial disease requiring a central venous catheter due to the primary (intracranial) disease. We excluded patients under the age of 19 yrs and those with active cardiac arrhythmia, full sepsis syndrome, bleeding diathesis and infection, or bleeding at the site of the intended catheter insertion. Male to female ratio was 31:20, and the median age was 55 yrs (range, 24-85 yrs). Forty-four of 51 patients (86.3%) had an initial Glasgow Coma Scale score of 3, three patients had a Glasgow Coma Scale score of 9, one patient presented with an initial Glasgow Coma Scale score of 11, two patients had an initial Glasgow Coma Scale score of 13, and one patient had an initial Glasgow Coma Scale score of 15. The mean initial tissue injury severity score was 45.1 and the median initial tissue injury severity score 45.0 (range, 19-70).

INTERVENTIONS

Patients were enrolled prospectively in a consecutive way. Within 12 hrs after admission, the intravascular cooling device (Cool Line catheter) was placed, the temperature probe was located within the bladder (by Foley catheter), and the Cool Gard cooling device was initiated. This Cool Gard system circulates temperature-controlled sterile saline through two small balloons mounted on the distal end of the Cool Line catheter. The patient's blood is gently cooled as it is passed over the balloons. The Cool Gard system has been set with a target temperature of 36.5 degrees C. The primary purpose and end point of this study was to evaluate the cooling capacity of this intravascular cooling device. Efficacy is expressed by the calculation formula of fever burden, which is defined as the fever time product ( degrees C hours) under the fever curve.

MEASUREMENTS AND MAIN RESULTS

The cooling device was in operation for a mean of 152.4 hrs. The ease of insertion was judged as easy in 42 of 51 patients; in a single patient, the catheter was malpositioned within the jugular vein, requiring early removal. The rate of infectious and noninfectious complications (nosocomial pneumonia, bacteremia, catheter-related ventriculitis, pulmonary embolism, etc.) was comparable to the rate usually observed in our neurologic intensive care patients with such severe intracranial diseases. The total fever burden within the entire study period of (on average) 152.4 hrs was 4.0 degrees C hrs/patient, being equivalent to 0.6 degrees C hrs/patient and day. Thirty of 51 patients showed an elevation of the body temperature (>37.9 degrees C) within 24 hrs after termination of the cooling study. One awake patient (subarachnoid hemorrhage, Glasgow Coma Scale score 15) experienced mild to moderate shivering throughout the entire period of 7 days. The mortality rate was 23.5%.

CONCLUSION

This novel intravascular cooling device (Cool Line catheter and Cool Gard cooling device) was highly efficacious in prophylactically controlling the body temperature of neurologic intensive care patients with very severe intracranial disease (median Glasgow Coma Scale score, 3-15). Morbidity and mortality rates were consistent with the ranges reported in the literature for such neurologic intensive patients.

Cyclooxygenase inhibitors attenuate endothelin ET(B) receptor-mediated contraction in human temporal artery

It is well documented that endothelin ET(B) receptor-mediated contraction develops in artery segments incubated in culture and that the reaction is augmented by proinflammatory cytokines, but little is known of the mechanisms involved. Segments of human temporal artery were incubated in organ culture for 2 days in the absence or presence of interleukin-1 beta (IL-1 beta), with or without nonsteroidal anti-inflammatory drugs, glucocorticoids or a nitric oxide synthase inhibitor. Thereafter, contractions were induced by the selective endothelin ET(B) receptor agonist, sarafotoxin S6c. Acetylsalicylic acid, indomethacin, nimesulide and rofecoxib were all effective in eliminating the increase in endothelin ET(B) receptor-mediated contraction induced by interleukin-1 beta, but only indomethacin and rofecoxib significantly reduced the spontaneous development of this reaction in cultured arteries. Dexamethasone and methylprednisolone augmented the reaction, and the nitric oxide synthase inhibitor had no effect. The results clearly indicate a role for cyclooxygenase, most likely cyclooxygenase-2, in endothelin ET(B) receptor-mediated contraction in this preparation.

Management of hyperthermia in traumatic brain injury

Recently there has been much interest in the use of hypothermia in the management of the brain-injured patient and its effect on outcome. Most of these studies examine the use of hypothermia compared with normothermia of 37 degrees C and have failed to demonstrate a benefit in the treatment groups, but what is normothermia in the brain-injured patient? Good epidemiologic evidence suggests that the vast majority of patients admitted to an ICU environment will develop a fever. The development of fever is clearly associated with a worse prognosis. There is now a better understanding of the possible mechanism of harm of fever and the side effects of cooling. Several treatment options for controlling temperature are discussed. Despite a sound physiologic argument for controlling fever in the brain-injured patient, there is no evidence that doing so will improve outcome.

Subarachnoid Hemorrhage

Patients presenting with subarachnoid hemorrhage from aneurysmal rupture benefit from early repair of the aneurysm. Recent advances in endovascular technology now allow informed discussion of the merits of surgical versus endovascular repair of the aneurysm. Patients need close observation in an intensive-care unit following subarachnoid hemorrhage to diagnose and treat the multiple complications that result. These complications include hydrocephalus, fever, neurogenic pulmonary and cardiac dysfunction, and the development of delayed cerebral ischemia from vasospasm. There exist effective medical and endovascular treatments for cerebral vasospasm.