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

Targeted Temperature Management for Severe Subarachnoid Hemorrhage Using Endovascular and Surface Cooling Systems: A Nonrandomized Interventional Study Using Historical Control

BACKGROUND

Although targeted temperature management (TTM) may mitigate brain injury for severe subarachnoid hemorrhage (SAH), rebound fever correlates with poor outcomes.

OBJECTIVE

To study the effect of endovascular TTM after rewarming from initial surface cooling during a high-risk period for delayed cerebral ischemia.

METHODS

We studied patients with World Federation of Neurological Surgeons grade V SAH before and after the introduction of endovascular TTM. Both groups (36 patients each) were treated with TTM at 34 °C with conventional surface cooling immediately after SAH diagnosis, together with emergency aneurysm repair. When rewarmed to 36 °C, around 7 days later, the study group underwent TTM at 36 to 38 °C for 7 days with an endovascular cooling system. The control group was treated with antipyretics.

RESULTS

Sex, age, Glasgow Coma Scale score, modified Fisher computed tomography classification, aneurysm location, and treatment methods were not different between the study and control groups. Differences were detected in the incidence of fever >38 °C (13 vs 26 patients, P = .0021), duration of fever >38 °C (4.1 vs 18.8 hours, P = .0021), incidence of vasospasm-related cerebral infarction (17% vs 42%, P = .037), and the likelihood of excellent outcomes (0 and 1 on a modified Rankin Scale) at 6 months (42% vs 17%, P = .037). In endovascular TTM, shivering occurred more frequently in patients with better outcomes, requiring aggressive treatment to avoid fever.

CONCLUSION

Endovascular TTM at 36 to 38 °C after surface cooling was feasible and safely performed in patients with severe SAH. Combined TTM for 2 weeks was associated with a lower incidence of vasospasm-related infarction and may improve outcomes.

In a model of SAH-induced neurogenic fever, BAT thermogenesis is mediated by erythrocytes and blocked by agonism of adenosine A1 receptors

Neurogenic fever (NF) after subarachnoid hemorrhage (SAH) is a major cause of morbidity that is associated with poor outcomes and prolonged stay in the neurointensive care unit (NICU). Though SAH is a much more common cause of fever than sepsis in the NICU, it is often a diagnosis of exclusion, requiring significant effort to rule out an infectious source. NF does not respond to standard anti-pyretic medications such as COX inhibitors, and lack of good medical therapy has led to the introduction of external cooling systems that have their own associated problems. In a rodent model of SAH, we measured the effects of injecting whole blood, blood plasma, or erythrocytes on the sympathetic nerve activity to brown adipose tissue and on febrile thermogenesis. We demonstrate that following SAH the acute activation of brown adipose tissue leading to NF, is not dependent on PGE₂, that subarachnoid space injection of whole blood or erythrocytes, but not plasma alone, is sufficient to trigger brown adipose tissue thermogenesis, and that activation of adenosine A1 receptors in the CNS can block the brown adipose tissue thermogenic component contributing to NF after SAH. These findings point to a distinct thermogenic mechanism for generating NF, compared to those due to infectious causes, and will hopefully lead to new therapies.

Feasibility and Safety of Transnasal High Flow Air to Reduce Core Body Temperature in Febrile Neurocritical Care Patients: A Pilot Study

BACKGROUND

Fever is an important determinant of prognosis following acute brain injury. Current non-pharmacologic techniques to reduce fever are limited and induce a shivering response. We investigated the safety and efficacy of a novel transnasal unidirectional high flow air device in reducing core body temperature in the neurocritical care unit (NCCU) setting.

METHODS

This pilot study included seven consecutive patients in the NCCU who were febrile (> 37.5 °C) for > 24 h despite standard non-pharmacologic and first-line antipyretic agents. Medical grade high flow air was delivered transnasally using a standard continuous positive airway pressure machine with a positive pressure of 20 cmH₂O for 2 h. Core esophageal and tympanic temperature were continuously monitored.

RESULTS

Mean age was 40 ± 14 yo, and 72% (5/7 patients) were men. Five patients had intracerebral or intraventricular hemorrhage, one subject had transverse myelitis, and the remaining patient had anoxic brain injury due to a cardiac arrest. After 2 h of cooling, core temperature was significantly lower than the baseline pre-cooling temperature (37.3 ± 0.5 °C vs. 38.4 ± 0.6 °C; p < 0.002). Mean transnasal airflow rate was 57.5 ± 6.5 liters per minute. Five of the seven subjects were normothermic at the end of the 2-h period. One subject with severe hyperthermia (39.7 °C) and the other with multiple interruptions to therapy due to technical reasons did not cool. The core temperature within 30 min of cessation of airflow increased and was similar to the pre-cooling baseline temperature (38.3 ± 0.4 °C vs. 38.4 ± 0.6 °C, p = NS). Rate of core cooling was 0.6 ± 0.15 °C per hour at this flow rate. No shivering response was observed. No protocol-related adverse events occurred.

CONCLUSIONS

High flow transnasal air in a unidirectional fashion lowers core body temperature in febrile patients in the NCCU setting. No adverse events were seen, and the process showed no signs of shivering or any other serious side effects during short-term exposure. This pilot study should inform further investigation.

[Catheter-related thrombosis during intravascular temperature management]

We report on a case of catheter-related thrombosis after 7‑day catheter placement during intravascular temperature management (IVTM), in spite of the use of prophylactic anticoagulants. There were no clinical sequelae. According to the literature, occult thrombosis during ITVM could be more frequent than previously reported and dedicated monitoring for potential thrombosis may be indicated. However, a study comparing IVTM with surface cooling found no differences in clinical outcome. Therefore, n either of the methods can be recommended over the other. Further studies should evaluate the rate of occult thrombosis during the use of both cooling methods.

Intraoperative mild hypothermia for postoperative neurological deficits in people with intracranial aneurysm

BACKGROUND

Rupture of an intracranial aneurysm causes aneurysmal subarachnoid haemorrhage, which is one of the most devastating clinical conditions. It can be classified into five Grades using the Hunt-Hess or World Federation of Neurological Surgeons (WFNS) scale. Grades 4 and 5 predict poor prognosis and are known as 'poor grade', while grade 1, 2, and 3 are known as 'good grade'. Disturbances of intracranial homeostasis and brain metabolism are known to play certain roles in the sequelae. Hypothermia has a long history of being used to reduce metabolic rate, thereby protecting organs where metabolism is disturbed, and may potentially cause harm.

OBJECTIVES

To assess the effect of intraoperative mild hypothermia on postoperative death and neurological deficits in people with ruptured or unruptured intracranial aneurysms.

SEARCH METHODS

We updated the search in the Cochrane Stroke Group Trials Register (August 2015), the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 8), WHO International Clinical Trials Registry Platform (ICTRP; December 2015), MEDLINE (1950 to September 2015), EMBASE (1980 to September 2015), Science Citation Index (1900 to September 2015), and 11 Chinese databases (September 2015). We also searched ongoing trials registers (September 2015) and scanned reference lists of retrieved records.

SELECTION CRITERIA

We included only randomised controlled trials that compared intraoperative mild hypothermia (32°C to 35°C) with control (no hypothermia) in people with ruptured or unruptured intracranial aneurysms.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials and assessed the risk of bias for each included study. We presented data as risk ratio (RR) and risk difference (RD) with 95% confidence intervals (CI).

MAIN RESULTS

We included three studies, enrolling 1158 participants. Each study reported an increased rate of recovery with intraoperative mild hypothermia, but the effect sizes were not sufficient for certainty. A total of 1086 of the 1158 participants (93.8%) had good grade aneurysmal subarachnoid haemorrhage. Seventy-six of 577 participants (13.1%) who received hypothermia and 93 of 581 participants (16.0%) who did not receive hypothermia were dead or dependent (RR 0.82; 95% CI 0.62 to 1.09; RD -0.03; 95% CI -0.07 to 0.01, moderate-quality evidence) after three months.Reported unfavourable outcomes did not differ between participants with or without hypothermia. The quality of evidence for these outcomes remains unclear because the outcomes were reported in a variety of ways. No decompressive craniectomy or corticectomy was reported. Thirty-six of 577 (6.2%) participants with hypothermia and 40 of 581 (6.9%) participants without hypothermia had infarction. Thirty-four of 577 (6%) participants with hypothermia and 32 of the 581 (5.5%) participants without hypothermia had clinical vasospasm (temporary deficits).Duration of hospital stay was not reported. Only one study with 112 participants reported discharge destinations: 43 of 55 (78.2%) participants with hypothermia and 39 of 57 (68.4%) participants in the control group were discharged home. The remaining participants were discharged to other facilities.Thirty-nine of 577 (6.8%) participants with hypothermia and 39 of 581 (6.7%) participants without hypothermia had infections. Six of 577 (1%) participants with hypothermia and 6 of 581 (1%) participants without hypothermia had cardiac arrhythmia.

AUTHORS' CONCLUSIONS

It remains possible that intraoperative mild hypothermia could prevent death or dependency in activities of daily living in people with good grade aneurysmal subarachnoid haemorrhage. However, the confidence intervals around this estimate include the possibility of both benefit and harm. There was insufficient information to draw any conclusions about the effects of intraoperative mild hypothermia in people with poor grade aneurysmal subarachnoid haemorrhage or without subarachnoid haemorrhage. We did not identify any reliable evidence to support the routine use of intraoperative mild hypothermia. A high-quality randomised clinical trial of intraoperative mild hypothermia for postoperative neurological deficits in people with poor grade aneurysmal subarachnoid haemorrhage might be feasible.

Using vascular closure devices following out-of-hospital cardiac arrest?

OBJECTIVES AND BACKGROUND

Despite a generally broad use of vascular closure devices (VCDs), it remains unclear whether they can also be used in victims from out-of-hospital cardiac arrest (OHCA) treated with mild therapeutic hypothermia (MTH).

METHODS

All victims from OHCA who received immediate coronary angiography after OHCA between January 1(st) 2008 and December 31(st) 2013 were included in this study. The operator decided to either use a VCD (Angio-Seal™) or manual compression for femoral artery puncture. The decision to induce MTH was based on the clinical circumstances.

RESULTS

76 patients were included in this study, 46 (60.5%) men and 30 (39.5%) women with a mean age of 64.2 ± 12.8 years. VCDs were used in 26 patients (34.2%), and 48 patients (63.2%) were treated with MTH. While there were significantly more overall vascular complications in the group of patients treated with MTH (12.5% versus 0.0%; p=0.05), vascular complications were similar between patients with VCD or manual compression, regardless of whether or not they were treated with MTH.

CONCLUSION

In our study, the overall rate of vascular complications related to coronary angiography was higher in patients treated with mild therapeutic hypothermia, but was not affected by the application of a vascular closure device. Therefore, our data suggest that the use of VCDs in victims from OHCA might be feasible and safe in patients treated with MTH as well, at least if the decision to use them is individually carefully determined.

Postsurgical meningitis complicated by severe refractory intracranial hypertension with limited treatment options: the role of mild therapeutic hypothermia

Intracranial hypertension is a commonly encountered neurocritical care problem. If first-tier therapy is ineffective, second-tier therapy must be initiated. In many cases, the full arsenal of established treatment options is available. However, situations occasionally arise in which only a narrow range of options is available to neurointensivists. We present a rare clinical scenario in which therapeutic hypothermia was the only available method for controlling intracranial pressure and that demonstrates the efficacy and safety of the Thermogard (Zoll, Chelmsford, Massachusetts, United States) cooling system in creating and maintaining a prolonged hypothermic state. The lifesaving effect of hypothermia was overshadowed by the unfavorable neurologic outcome observed (minimally conscious state on intensive care unit discharge). These results add further evidence to support the role of therapeutic hypothermia in managing intracranial pressure and provide motivation for finding new strategies in combination with hypothermia to improve neurologic outcomes.

Modest cooling therapies (35ºC to 37.5ºC) for traumatic brain injury

BACKGROUND

Animal models of traumatic brain injury suggest that induced normothermia (36.5 or 37 ºC), compared to induced hyperthermia (39 ºC), improves histopathological and neurobehavioural outcomes. Observational clinical studies of patients with TBI suggest an association between raised body temperature and unfavourable outcome, although this relationship is inconsistent.

OBJECTIVES

To assess the effects of modest cooling therapies (defined as any drug or physical therapy aimed at maintaining body temperature between 35 ºC and 37.5 ºC) when applied to patients in the first week after traumatic brain injury.

SEARCH METHODS

The most recent search was run on 23(rd) September 2013. We searched the Cochrane Injuries Group's Specialised Register, The Cochrane Library (CENTRAL), MEDLINE (OvidSP), Embase (OvidSP), ISI WOS: SCI-EXPANDED (1970) & CPCI-S (1990), PubMed and trials registries together with reference checking.

SELECTION CRITERIA

All completed randomised, controlled and placebo-controlled trials published or unpublished, where modest cooling therapies were applied in the first week after traumatic brain injury.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the selection criteria to relevant trials.

MAIN RESULTS

We were unable to find any randomised controlled trials of modest cooling therapies after traumatic brain injury.

AUTHORS' CONCLUSIONS

In order to further explore the preliminary findings provided by animal models and observational clinical studies that suggests there may be a beneficial effect of modest cooling for TBI, randomised trials designed to explore the effect of these interventions on patient-centred outcomes are needed.

Drug-induced hypothermia in stroke models: does it always protect?

Ischemic stroke is a common neurological disorder lacking a cure. Recent studies show that therapeutic hypothermia is a promising neuroprotective strategy against ischemic brain injury. Several methods to induce therapeutic hypothermia have been established; however, most of them are not clinically feasible for stroke patients. Therefore, pharmacological cooling is drawing increasing attention as a neuroprotective alternative worthy of further clinical development. We begin this review with a brief introduction to the commonly used methods for inducing hypothermia; we then focus on the hypothermic effects of eight classes of hypothermia-inducing drugs: the cannabinoids, opioid receptor activators, transient receptor potential vanilloid, neurotensins, thyroxine derivatives, dopamine receptor activators, hypothermia-inducing gases, adenosine, and adenine nucleotides. Their neuroprotective effects as well as the complications associated with their use are both considered. This article provides guidance for future clinical trials and animal studies on pharmacological cooling in the setting of acute stroke.

Keep the brain cool--endovascular cooling in patients with severe traumatic brain injury: a case series study

BACKGROUND

As brain temperature is reported to be extensively higher than core body temperature in traumatic brain injury (TBI) patients, posttraumatic hyperthermia is of particular relevance in the injured brain.

OBJECTIVE

To study the influence of prophylactic normothermia on brain temperature and the temperature gradient between brain and core body in patients with severe TBI using an intravascular cooling system and to assess the relationship between brain temperature and intracranial pressure (ICP) under endovascular temperature control.

METHODS

Prospective case series study conducted in the neurologic intensive care unit of a tertiary care university hospital. Seven patients with severe TBI with a Glasgow Coma Scale score of 8 or less were consecutively enrolled. Prophylactic normothermia, defined as a target temperature of 36.5°C, was maintained using an intravascular cooling system. Simultaneous measurements of brain and urinary bladder temperature and ICP were taken over a 72-hour period.

RESULTS

The mean bladder temperature in normothermic patients was 36.3 ± 0.4°C, and the mean brain temperature was determined as 36.4 ± 0.5°C. The mean temperature difference between brain and bladder was 0.1°C. We found a significant direct correlation between brain and bladder temperature (r = 0.95). In 52.4% of all measurements, brain temperature was higher than core body temperature. The mean ICP was 18 ± 8 mm Hg.

CONCLUSION

Intravascular temperature management stabilizes both brain and body core temperature; prophylactic normothermia reduces the otherwise extreme increase of intracerebral temperature in patients with severe TBI. The intravascular cooling management proved to be an efficacious and feasible method to control brain temperature and to avoid hyperthermia in the injured brain. We could not find a statistically significant correlation between brain temperature and ICP.

Intraoperative mild hypothermia for postoperative neurological deficits in intracranial aneurysm patients

BACKGROUND

Rupture of an intracranial aneurysm causes aneurysmal subarachnoid haemorrhage, which is one of the most devastating clinical conditions. Clinically, it can be classified into five grades using the Hunt-Hess or World Federation of Neurological Surgeons (WFNS) scale. Grades 4 and 5 predict poor prognosis and are called 'poor grade', while grade 1, 2, and 3 are known as 'good grade'. Disturbances of intracranial homeostasis and brain metabolism are known to play certain roles in the sequelae. Hypothermia has a long history of being used to reduce metabolism rate, thereby protecting organs in cases where metabolism is disturbed and potentially harmful.

OBJECTIVES

To assess the effect of intraoperative mild hypothermia on postoperative death and neurological deficits in patients with intracranial aneurysms (ruptured or unruptured).

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (September 2011), the Cochrane Central Register of Controlled Trials (CENTRAL 2011, Issue 3), MEDLINE (1950 to September 2011), EMBASE (1980 to September 2011), Science Citation Index (1900 to September 2011) and 11 Chinese databases (September 2011). We also searched ongoing trials registers (September 2011) and scanned reference lists of retrieved records.

SELECTION CRITERIA

We included only randomised controlled trials comparing intraoperative mild hypothermia (32°C to 35°C) with control (no hypothermia) in patients with intracranial aneurysms (ruptured or unruptured).

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials and assessed the risk of bias for each included study. We presented data as risk ratio (RR) with 95% confidence intervals (CI).

MAIN RESULTS

We included three studies enrolling 1158 patients. Each study observed an increased rate of good recovery with intraoperative mild hypothermia, but the effect sizes were not sufficient for statistical significance. A total of 76 of 577 patients (13.1%) who received hypothermia and 93 of 581 patients (16.0%) who did not receive hypothermia were dead or dependent. A total of 1086 of the1158 patients (93.8%) had good-grade aneurysmal subarachnoid haemorrhage. A random-effects meta-analysis resulted in a summarised RR of 0.82 (95% CI 0.62 to 1.09, P value 0.17). In patients with poor-grade aneurysmal subarachnoid haemorrhage, one of seven in the hypothermia group and one of six in the control group were dead or dependent (RR 0.86, 95% CI 0.07 to 10.96, P value 0.91). In patients without subarachnoid haemorrhage, three of 30 patients (10%) in the hypothermia group, and four of 29 patients (13.8%) in the control group were dead or dependent (RR 0.72, 95% CI 0.18 to 2.96, P value 0.65).

AUTHORS' CONCLUSIONS

In patients with good-grade aneurysmal subarachnoid haemorrhage, intraoperative mild hypothermia might prevent death or dependency in activities of daily living for a few of them. However, the confidence intervals include the possibility of both benefit and harm. There is no evidence that intraoperative mild hypothermia is harmful. This treatment should not be routinely applied. In patients with poor-grade aneurysmal subarachnoid haemorrhage or without subarachnoid haemorrhage, there are insufficient data to draw any conclusions. A high-quality randomised clinical trial of intraoperative mild hypothermia for postoperative neurological deficits in patients with poor-grade aneurysmal subarachnoid haemorrhage might be feasible.

The effect of decompressive hemicraniectomy on brain temperature after severe brain injury

BACKGROUND

Animal studies have shown that even a small temperature elevation of 1°C can cause detrimental effects after brain injury. Since the skull acts as a potential thermal insulator, we hypothesized that decompressive hemicraniectomy facilitates surface cooling and lowers brain temperature.

METHODS

Forty-eight patients with severe brain injury (TBI = 38, ICH = 10) with continuous brain temperature monitoring were retrospectively studied and grouped into "hemicraniectomy" (n = 20) or "no hemicraniectomy" (n = 28) group. The paired measurements of core body (T Core) and brain (T Br) temperature were recorded at 1-min intervals over 12 ± 7 days. As a surrogate measure for the extent of surface heat loss from the brain, ∆T Core-Br was calculated as the difference between T Core and T Br with each recording. In order to accommodate within-patient temperature correlations, mixed-model regression was used to assess the differences in ∆T Core-Br between those with and without hemicraniectomy, adjusted for core body temperature and diagnosis.

RESULTS

A total of 295,883 temperature data pairs were collected (median [IQR] per patient: 5047 [3125-8457]). Baseline characteristics were similar for age, sex, diagnosis, incidence of sepsis, Glasgow Coma Scale score, ICU mortality, and ICU length of stay between the two groups. The mean difference in ∆T Core-Br was 1.29 ± 0.87°C for patients with and 0.80 ± 0.86°C for patients without hemicraniectomy (P < 0.0001). In mixed-model regression, accounting for temperature correlations within patients, hemicraniectomy and higher T Core were associated with greater ∆T Core-Br (hemicraniectomy: estimated effect = 0.60, P = 0.003; T Core: estimated effect = 0.21, P < 0.0001).

CONCLUSIONS

Hemicraniectomy is associated with modestly but significantly lower brain temperature relative to core body temperature.

Fever management in SAH

An electronic literature search through August 2010 was performed to obtain articles describing fever incidence, impact, and treatment in patients with subarachnoid hemorrhage. A total of 24 original research studies evaluating fever in SAH were identified, with studies evaluating fever and outcome, temperature control strategies, and shivering. Fever during acute hospitalization for subarachnoid hemorrhage was consistently linked with worsened outcome and increased mortality. Antipyretic medications, surface cooling, and intravascular cooling may all reduce temperatures in patients with subarachnoid hemorrhage; however, benefits from cooling may be offset by negative consequences from shivering.

Therapeutic hypothermia for out-of-hospital cardiac arrest: an update for neurosurgeons

BACKGROUND

Neurosurgeons have been familiar with the idea that hypothermia is protective against various types of brain injuries, including traumatic brain injury (TBI). Recent randomized controlled trials, however, have failed to demonstrate the efficacy of therapeutic hypothermia (TH) in patients with TBI. On the other hand, TH becomes popular in the treatment of out-of-hospital cardiac arrest (OHCA) survivors, after randomized controlled trials have shown that survival rate and functional outcome is improved with the use of TH in selected patients. We believe that knowledge on the recent progress in TH for OHCA is useful for neurosurgeons, because feedback of information obtained in the treatment of OHCA may revitalize the interest in TH for neurosurgical disorders, particularly TBI.

METHODS

A review of the literature was conducted with the use of PubMed.

RESULTS

Various cooling techniques and devices have been developed and trialed in the treatment of OHCA survivors, including prehospital cooling with bolus ice-cold saline, endovascular cooling catheters, and new generation surface cooling devices, some of which have already been known to neurosurgeons. The efficacy of these new methods and devices has been demonstrated in many preliminary studies, and phase III trials are also expected.

CONCLUSIONS

Neurosurgeons and critical care medicine physicians pursue the same goal of rescuing the brain from the secondary injury despite the difference in etiology (focal trauma vs. global ischemia), with the presumption that earlier and faster implementation of TH will result in better outcome. Thoughtful application of knowledge and techniques obtained in OHCA to TBI under a rigorously controlled situation will make a small, but significant difference in the outcome of TBI victims.

Current and future role of therapeutic hypothermia

Therapeutic moderate hypothermia has been advocated for use in traumatic brain injury, stroke, cardiac arrest-induced encephalopathy, neonatal hypoxic-ischemic encephalopathy, hepatic encephalopathy, and spinal cord injury, and as an adjunct to aneurysm surgery. In this review, we address the trials that have been performed for each of these indications, and review the strength of the evidence to support treatment with mild/moderate hypothermia. We review the data to support an optimal target temperature for each indication, as well as the duration of the cooling, and the rate at which cooling is induced and rewarming instituted. Evidence is strongest for prehospital cardiac arrest and neonatal hypoxic-ischemic encephalopathy. For traumatic brain injury, a recent meta-analysis suggests that cooling may increase the likelihood of a good outcome, but does not change mortality rates. For many of the other indications, such as stroke and spinal cord injury, trials are ongoing, but the data are insufficient to recommend routine use of hypothermia at this time.

Methods of cooling: practical aspects of therapeutic temperature management

OBJECTIVES

To review traditional and newer means of inducing, maintaining, and withdrawing therapeutic hypothermia and normothermia. To suggest treatment algorithms for temperature modulation and review neuromonitoring options.

DESIGN

A review of current literature describing methods of performing therapeutic temperature management and neuromonitoring during the cooling, maintenance, and decooling periods. Algorithms for performing therapeutic temperature management are suggested.

RESULTS

Temperature management can be safely and effectively performed using traditional or newer modalities. Although traditional means of cooling are feasible and efficacious, modern devices utilizing feedback loops to maintain steady body temperature and prevent overcooling have advantages in ease of application, patient safety, maintenance of target temperature, and control of decooling. Neuromonitoring options should be adapted to an individual patient and situation.

CONCLUSIONS

Intensivists should be familiar with techniques to induce, maintain, and withdraw therapeutic temperature management, and select the most appropriate method for a given patient and situation.

Methodologic challenges in the design and conduct of hyperacute stroke research

Stroke is the third leading cause of death in the United States and the leading cause of adult disability, consistently ranking in the top 10 of leading diagnostic categories encountered by practitioners in emergency and critical care settings. Despite its prevalence and clinical significance, only tissue plasminogen activator for ischemic stroke has been shown to reduce 3-month mortality and disability in phase III clinical trials, whereas for hemorrhagic stroke, no medicinal treatment has yet to demonstrate a similar reduction in mortality or disability. This article describes challenges inherent in the design and conduct of hyperacute stroke trials. Sample heterogeneity associated with pathophysiologic stroke mechanisms, the neurovascular territory implicated, systemic and intracranial hemodynamics, risk factor profiles, and patient access to requisite healthcare services are reviewed as contributors challenging enrollment into well-designed studies. Current controversies associated with designation of endpoints are presented and strategies to enhance trial design, and subsequent enrollment, are discussed. Recommendations are made for future clinical research into phenomena associated with hyperacute stroke.

Modest cooling therapies (35 degrees C to 37.5 degrees C) for traumatic brain injury

BACKGROUND

A recent retrospective study suggested that after traumatic brain injury, patients with a raised body temperature have an unfavourable outcome compared to patients that have a normal body temperature.

OBJECTIVES

To assess the effects of modest cooling therapies (defined as any drug or physical therapy aimed at maintaining body temperature between 35 degrees C and 37.5 degrees C) when applied to patients in the first week after traumatic brain injury.

SEARCH STRATEGY

We searched the Cochrane Injuries Group's Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 3), MEDLINE (1950 to 2008), EMBASE (1980 to 2008), the National Research Register, Zetoc and the Current Controlled Trials MetaRegister of controlled trials. We also contacted investigators, pharmaceutical companies and the manufacturers of cooling equipment. The searches were conducted August to September 2007 and updated in April 2008.

SELECTION CRITERIA

All completed randomised, controlled or placebo-controlled trials published or unpublished, where modest cooling therapies were applied in the first week after traumatic brain injury.

DATA COLLECTION AND ANALYSIS

Two authors independently searched for relevant trials.

MAIN RESULTS

We were unable to find any randomised, placebo-controlled trials of modest cooling therapies after traumatic brain injury.

AUTHORS' CONCLUSIONS

There is no evidence that interventions aimed at reducing body temperature to between 35 degrees C and 37.5 degrees C in the first week after TBI improves patient outcomes. Trials designed to explore the effect of these interventions on patient-centred outcomes are needed.

Antipyretic treatment of noninfectious fever in children with severe traumatic brain injury

OBJECTIVE

The purpose of this study was to describe the treatment of noninfectious fever in children with severe traumatic brain injury (TBI).

MATERIALS AND METHODS

We conducted a retrospective study to compare type of and response to antipyretic treatment strategies in children less than or equal to 17 years and Glasgow Coma Scale (GCS) score less than 9.

RESULTS

The average admission GCS score was 4. Forty children (35 boys, 5 girls), age 7.8 +/- 5.2 years, had noninfectious fever. Seventy percent (28 of 40) received acetaminophen only, and 30% (12 of 40) received acetaminophen plus either ibuprofen or physical cooling. Time to next febrile episode was longer in patients receiving combination therapy than those receiving monotherapy (p = 0.03). Fever refractory to treatment dose or strategy occurred in more than 40% of the patients.

CONCLUSIONS

Early combination antipyretic therapy may be needed to effectively maintain normothermia in children with severe TBI.