Clinical trial of an air-circulating cooling blanket for fever control in critically ill neurologic patients

Targeted Temperature Management in Brain Injured Patients

Evidence from animal models indicates that lowering temperature by a few degrees can produce substantial neuroprotection. In humans, hypothermia has been found to be neuroprotective with a significant impact on mortality and long-term functional outcome only in cardiac arrest and neonatal hypoxic-ischemic encephalopathy. Clinical trials have explored the potential role of maintaining normothermia and treating fever in critically ill brain injured patients. This review concentrates on basic concepts to understand the physiologic interactions of thermoregulation, effects of thermal modulation in critically ill patients, proposed mechanisms of action of temperature modulation, and practical aspects of targeted temperature management.

Targeted Temperature Management in Brain Injured Patients

Evidence from animal models indicates that lowering temperature by a few degrees can produce substantial neuroprotection. In humans, hypothermia has been found to be neuroprotective with a significant impact on mortality and long-term functional outcome only in cardiac arrest and neonatal hypoxic-ischemic encephalopathy. Clinical trials have explored the potential role of maintaining normothermia and treating fever in critically ill brain injured patients. This review concentrates on basic concepts to understand the physiologic interactions of thermoregulation, effects of thermal modulation in critically ill patients, proposed mechanisms of action of temperature modulation, and practical aspects of targeted temperature management.

Comparison of Two Surface Cooling Devices for Temperature Management in a Neurocritical Care Unit

Fever increases mortality and morbidity and length of stay in neurocritically ill patients. Various methods are used in the neuroscience intensive care unit (NSICU) to control fever. Two such methods involve the Arctic Sun hydrogel wraps and the Gaymar cooling wraps. The purpose of our study was to compare these two methods in neurocritical care patients who had temperature >37.5°C for more than three consecutive hours and that was refractory to standard treatments. Data of patients requiring cooling wraps for treatment of hyperthermia at an NSICU at an academic, tertiary referral center were retrospectively reviewed. The average temperature before cooling was 38.5°C ± 0.38°C and 38.4°C ± 0.99°C for the Gaymar and Arctic Sun groups, respectively (p = 0.89). The Gaymar group took on average 16 ± 21.9 hours to reach goal temperature, whereas the Arctic Sun group took 2.22 ± 1.39 hours (p = 0.08). The average time outside of the target temperature was 57.0 ± 58.0 hours in the Gaymar group compared with 13.7 ± 17.1 hours in the Arctic Sun group (p = 0.04). Average duration of using the cooling wraps was similar between the two groups; 81.8% of patients had rebound hyperthermia in the Gaymar group compared with 20% in the Arctic Sun group (p = 0.0089). The Arctic Sun group had a nonsignificant increased incidence of shivering compared with the Gaymar group (40% vs. 18.18%, p = 0.36). We found that Arctic Sun surface cooling device was more efficient in attaining the target temperature, had less incidence of rebound hyperthermia, and was able to maintain normothermia better than Gaymar cooling wraps. The incidence of shivering tended to be more common in the Arctic Sun group.

Paracetamol in fever in critically ill patients-an update

Fever, which is arbitrary defined as an increase in body temperature above 38.3°C, can affect up to 90% of patients admitted in intensive care unit. Induction of fever is mediated by the release of pyrogenic cytokines (tumor necrosis factor α, interleukin 1, interleukin 6, and interferons). Fever is associated with increased length of stay in intensive care unit and with a worse outcome in some subgroups of patients (mainly neurocritically ill patients). Although fever can increase oxygen consumption in unstable patients, on the contrary, it can activate physiologic systems that are involved in pathogens clearance. Treatments to reduce fever include the use of antipyretics. Thus, the reduction of fever might reduce the ability to develop an efficient host response. This balance, between harms and benefits, has to be taken into account every time we decide to treat or not to treat fever in a given patient. Among the antipyretics, paracetamol is one of the most common used. Paracetamol is a synthetic, nonopioid, centrally acting analgesic, and antipyretic drug. Its antipyretic effect occurs because it inhibits cyclooxygenase-3 and the prostaglandin synthesis, within the central nervous system, resetting the hypothalamic heat-regulation center. In this clinical review, we will summarize the use of paracetamol as antipyretic in critically ill patients (sepsis, trauma, neurological, and medical).

Critical Care Management of Increased Intracranial Pressure

Increased intracranial pressure (ICP) is a pathologic state common to a variety of serious neurologic conditions, all of which are characterized by the addition of volume to the intracranial vault. Hence all ICP therapies are directed toward reducing intracranial volume. Elevated ICP can lead to brain damage or death by two principle mechanisms: (1) global hypoxic-ischemic injury, which results from reduction of cerebral perfusion pressure (CPP) and cerebral blood flow, and (2) mechanical compression, displacement, and herniation of brain tissue, which results from mass effect associated with compartmentalized ICP gradients. In unmonitored patients with acute neurologic deterioration, head elevation (30 degrees), hyperventilation (pCO2 26-30 mmHg), and mannitol (1.0-1.5 g/kg) can lower ICP within minutes. Fluid-coupled ventricular catheters and intraparenchymal pressure transducers are the most accurate and reliable devices for measuring ICP in the intensive care unit (ICU) setting. In a monitored patient, treatment of critical ICP elevation (>20 mmHg) should proceed in the following steps: (1) consideration of repeat computed tomography (CT) scanning or consideration of definitive neurosurgical intervention, (2) intravenous sedation to attain a quiet, motionless state, (3) optimization of CPP to levels between 70 and 110 mmHg, (4) osmotherapy with mannitol or hypertonic saline, (5) hyperventilation (pCO2 26-30 mmHg), (6) high-dose pentobarbital therapy, and (7) systemic cooling to attain moderate hypothermia (32-33°C). Placement of an ICP monitor and use of a stepwise treatment algorithm are both essential for managing ICP effectively in the ICU setting.

Perioperative thermoregulation and heat balance

Core body temperature is normally tightly regulated to within a few tenths of a degree. The major thermoregulatory defences in humans are sweating, arteriovenous shunt vasoconstriction, and shivering. The core temperature triggering each response defines its activation threshold. General anaesthetics greatly impair thermoregulation, synchronously reducing the thresholds for vasoconstriction and shivering. Neuraxial anaesthesia also impairs central thermoregulatory control, and prevents vasoconstriction and shivering in blocked areas. Consequently, unwarmed anaesthetised patients become hypothermic, typically by 1-2°C. Hypothermia results initially from an internal redistribution of body heat from the core to the periphery, followed by heat loss exceeding metabolic heat production. Complications of perioperative hypothermia include coagulopathy and increased transfusion requirement, surgical site infection, delayed drug metabolism, prolonged recovery, shivering, and thermal discomfort. Body temperature can be reliably measured in the oesophagus, nasopharynx, mouth, and bladder. The standard-of-care is to monitor core temperature and to maintain normothermia during general and neuraxial anaesthesia.

Fever and therapeutic normothermia in severe brain injury: an update

PURPOSE OF REVIEW

Fever is common in the ICU among patients with severe brain injury. Fever has been consistently shown to exacerbate brain injuries in animal models and has been consistently associated with poor outcome in human studies. However, whether fever control improves outcome and the ideal means of fever control remain unknown. This review will address recent literature on the impact of fever on severe brain injury and on interventions to maintain normothermia.

RECENT FINDINGS

Current guidelines generally recommend maintenance of normothermia after brain injury but have scant recommendations on methods to do this. Observational trials have continued to demonstrate the association between fever and poor outcome after severe brain injury. Recent trials have shown the efficacy of more aggressive approaches to fever reduction, whereas a large randomized trial showed the relative ineffectiveness of acetaminophen alone for fever control. Several studies have also described the impact of fever and of fever control on brain physiology.

SUMMARY

The value of therapeutic normothermia in the neurocritical care unit (NCCU) is increasingly accepted, yet prospective trials that demonstrate a functional benefit to patients are lacking.

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.

Treatment of fever after stroke: conflicting evidence

Approximately 50% of patients hospitalized for stroke develop fever. In fact, experimental evidence suggests that high body temperature is significantly correlated to initial stroke severity, lesion size, mortality, and neurologic outcome. Fever occurring after stroke is associated with poor outcomes. We investigated the etiology of fever after stroke and present evidence evaluating the efficacy and safety of interventions used to treat stroke-associated fever. Oral antipyretics are only marginally effective in lowering elevated body temperature in this population and may have unintended adverse consequences. Nonpharmacologic approaches to cooling have been more effective in achieving normothermia, but whether stroke outcomes can be improved remains unclear. We recommend using body temperature as a biomarker and a catalyst for aggressive investigation for an infectious etiology. Care must be taken not to exceed the new standard of a maximum acetaminophen dose of 3 g/day to avoid patient harm.

Intracranial hemorrhage

Intracranial hemorrhage is a life-threatening condition, the outcome of which can be improved by intensive care. Intracranial hemorrhage may be spontaneous, precipitated by an underlying vascular malformation, induced by trauma, or related to therapeutic anticoagulation. The goals of critical care are to assess the proximate cause, minimize the risks of hemorrhage expansion through blood pressure control and correction of coagulopathy, and obliterate vascular lesions with a high risk of acute rebleeding. Simple bedside scales and interpretation of computed tomography scans assess the severity of neurological injury. Myocardial stunning and pulmonary edema related to neurological injury should be anticipated, and can usually be managed. Fever (often not from infection) is common and can be effectively treated, although therapeutic cooling has not been shown to improve outcomes after intracranial hemorrhage. Most functional and cognitive recovery takes place weeks to months after discharge; expected levels of functional independence (no disability, disability but independence with a device, dependence) may guide conversations with patient representatives. Goals of care impact mortality, with do-not-resuscitate status increasing the predicted mortality for any level of severity of intraparenchymal hemorrhage. Future directions include refining the use of bedside neuro-monitoring (electroencephalogram, invasive monitors), novel approaches to reduce intracranial hemorrhage expansion, minimizing vasospasm, and refining the assessment of quality of life to guide rehabilitation and therapy.

Induced hypothermia for trauma: current research and practice

Induction of hypothermia with the goal of providing therapeutic benefit has been accepted for use in the clinical setting of adult cardiac arrest and neonatal hypoxic-ischemic encephalopathy (HIE). However, its potential as a treatment in trauma is not as well defined. This review discusses potential benefits and complications of induced hypothermia (IH) with emphasis on the current state of knowledge and practice in various types of trauma. There is excellent preclinical research showing that in cases of penetrating trauma with cardiac arrest, inducing hypothermia to 10 degrees C using cardiopulmonary bypass (CPB) could possibly save those otherwise likely to die without causing neurologic sequelae. A human trial of this intervention is about to get underway. Preclinical studies suggest that inducing hypothermia may be useful to delay cardiac arrest in penetrating trauma victims who are hypotensive. There is potential for IH to be used in cases of blunt trauma, but it has not been well studied. In the case of traumatic brain injury (TBI), clinical trials have shown conflicting results, despite almost uniform efficacy seen in preclinical experiments. Major studies are analyzed and ways to standardize its use and optimize future clinical trials are discussed. More preclinical and clinical research is needed to better define whether there could be a role for IH in the case of spinal cord injuries.

Impact of Induced Normothermia on Outcome After Subarachnoid Hemorrhage

OBJECTIVE

Fever during the first week after subarachnoid hemorrhage (SAH) is associated with poor outcome; however, eliminating fever has not been shown to improve outcome. We sought to explore the potential impact of induced normothermia using advanced fever control (AFC) methods on outcome after SAH.

METHODS

We identified 40 consecutive febrile patients enrolled in the Columbia University SAH Outcomes Project between 2003 and 2005 who underwent AFC (37°C) with a surface cooling device during the first 14 days after SAH and randomly matched by age, Hunt and Hess grade, and SAH sum score to 80 SAH patients who underwent conventional fever control between 1996 and 2004. Average daily fever burden was calculated as the time and extent (°C × hours) above 37°C. Poor outcome was defined as death or moderate to severe disability (modified Rankin Scale score of 4 or higher). A multivariate analysis was performed to identify factors associated with poor outcome 12 months after SAH.

RESULTS

The fever burden was lower over 14 days in the AFC patients as compared with the patients receiving conventional fever control (P < .001). AFC patients had higher rates of hyperglycemia (P < .01) and arrhythmias (P = .02). Higher admission Hunt and Hess grade on admission and the development of pneumonia (P = .02) were associated with an increased risk for poor outcome at 12 months (P = .04), whereas AFC was associated with a reduced risk (P = .004) after adjusting for age, arrhythmia, and anemia.

CONCLUSION

Elimination of fever with AFC may be associated with improved outcome after SAH. A prospective randomized trial of AFC vs conventional fever control is warranted.

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.

[Therapeutic hypothermia in neurocritical patients]

Induced hypothermia in neurocritical patients is one of the most promising neuroprotective therapies in the last decade. Unfortunately, the promising results obtained in experimental studies have had an unequal reflection in the different diseases that affect the neurocritical patient. The use of therapeutic hypothermia is clearly established in patients with neurological deterioration after cardiac arrest. On the contrary, its use in patients with traumatic brain injury is highly controversial. There is not enough evidence in stroke and hemorrhagic patients to support its use except in clinical trials. Nowadays, the greater understanding of the pathophysiology of secondary brain damage, the go od clinical results obtained in randomized clinical trials in patients with cerebral anoxia after ventricular fibrillation and the new cooling methods that have appeared have improved the interest of hypothermia in neurocritical patients. Induced hypothermia has a role in the intensive care unit. Critical care physicians should be familiar with the physiologic effects, current indications, techniques, and complications of induced hypothermia. This review elaborates on the clinical implications of hypothermia research in traumatic brain injury, anoxic, brain injury, stroke and intracerebral hemorrhage.

Cooling therapy for acute stroke

BACKGROUND

Increased body temperatures are common in patients with acute stroke and are associated with poor outcome. In animal models of focal cerebral ischaemia, temperature-lowering therapy reduces infarct volume. In patients with acute stroke, lowering temperature may therefore improve outcome. This is an update of a Cochrane review first published in 1999.

OBJECTIVES

To assess the effects of pharmacological and physical strategies to reduce body or brain temperature in patients with acute stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group trials register (last searched December 2007). In addition, we searched MEDLINE and EMBASE (January 1998 to December 2007). We scanned references and contacted authors of included trials. For the previous version of this review, the authors contacted pharmaceutical companies and manufactures of cooling equipment in this field.

SELECTION CRITERIA

We considered all completed randomised or non-randomised controlled clinical trials, published or unpublished, where pharmacological or physical strategies or both to reduce temperature were applied in patients with acute ischaemic stroke or intracerebral haemorrhage. Outcome measures were death or dependency (modified Rankin Scale score >/= 3) at the end of follow up, and adverse effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the inclusion criteria, assessed trial quality, and extracted and cross-checked the data.

MAIN RESULTS

We included five pharmacological temperature reduction trials and three physical cooling trials involving a total of 423 participants. We found no statistically significant effect of pharmacological or physical temperature-lowering therapy in reducing the risk of death or dependency (odds ratio (OR) 0.9, 95% confidence interval (CI) 0.6 to 1.4) or death (OR 0.9, 95% CI 0.5 to 1.5). Both interventions were associated with a non-significant increase in the occurrence of infections.

AUTHORS' CONCLUSIONS

There is currently no evidence from randomised trials to support routine use of physical or pharmacological strategies to reduce temperature in patients with acute stroke. Large randomised clinical trials are needed to study the effect of such strategies.

Clinical review: Critical care management of spontaneous intracerebral hemorrhage

Intracerebral hemorrhage is by far the most destructive form of stroke. The clinical presentation is characterized by a rapidly deteriorating neurological exam coupled with signs and symptoms of elevated intracranial pressure. The diagnosis is easily established by the use of computed tomography or magnetic resonance imaging. Ventilatory support, blood pressure control, reversal of any preexisting coagulopathy, intracranial pressure monitoring, osmotherapy, fever control, seizure prophylaxis, treatment of hyerglycemia, and nutritional supplementation are the cornerstones of supportive care in the intensive care unit. Dexamethasone and other glucocorticoids should be avoided. Ventricular drainage should be performed urgently in all stuporous or comatose patients with intraventricular blood and acute hydrocephalus. Emergent surgical evacuation or hemicraniectomy should be considered for patients with large (>3 cm) cerebellar hemorrhages, and in those with large lobar hemorrhages, significant mass effect, and a deteriorating neurological exam. Apart from management in a specialized stroke or neurological intensive care unit, no specific medical therapies have been shown to consistently improve outcome after intracerebral hemorrhage.

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.

Temperature monitoring and perioperative thermoregulation

Most clinically available thermometers accurately report the temperature of whatever tissue is being measured. The difficulty is that no reliably core-temperature-measuring sites are completely noninvasive and easy to use-especially in patients not undergoing general anesthesia. Nonetheless, temperature can be reliably measured in most patients. Body temperature should be measured in patients undergoing general anesthesia exceeding 30 min in duration and in patients undergoing major operations during neuraxial anesthesia. Core body temperature is normally tightly regulated. All general anesthetics produce a profound dose-dependent reduction in the core temperature, triggering cold defenses, including arteriovenous shunt vasoconstriction and shivering. Anesthetic-induced impairment of normal thermoregulatory control, with the resulting core-to-peripheral redistribution of body heat, is the primary cause of hypothermia in most patients. Neuraxial anesthesia also impairs thermoregulatory control, although to a lesser extent than does general anesthesia. Prolonged epidural analgesia is associated with hyperthermia whose cause remains unknown.

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.

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.

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.

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.

Comparison of cooling methods to induce and maintain normo- and hypothermia in intensive care unit patients: a prospective intervention study

Background

Temperature management is used with increased frequency as a tool to mitigate neurological injury. Although frequently used, little is known about the optimal cooling methods for inducing and maintaining controlled normo- and hypothermia in the intensive care unit (ICU). In this study we compared the efficacy of several commercially available cooling devices for temperature management in ICU patients with various types of neurological injury.

Methods

Fifty adult ICU patients with an indication for controlled mild hypothermia or strict normothermia were prospectively enrolled. Ten patients in each group were assigned in consecutive order to conventional cooling (that is, rapid infusion of 30 ml/kg cold fluids, ice and/or coldpacks), cooling with water circulating blankets, air circulating blankets, water circulating gel-coated pads and an intravascular heat exchange system. In all patients the speed of cooling (expressed as°C/h) was measured. After the target temperature was reached, we measured the percentage of time the patient's temperature was 0.2°C below or above the target range. Rates of temperature decline over time were analyzed with one-way analysis of variance. Differences between groups were analyzed with one-way analysis of variance, with Bonferroni correction for multiple comparisons. A p < 0.05 was considered statistically significant.

Results

Temperature decline was significantly higher with the water-circulating blankets (1.33 ± 0.63°C/h), gel-pads (1.04 ± 0.14°C/h) and intravascular cooling (1.46 ± 0.42°C/h) compared to conventional cooling (0.31 ± 0.23°C/h) and the air-circulating blankets (0.18 ± 0.2°C/h) (p < 0.01). After the target temperature was reached, the intravascular cooling device was 11.2 ± 18.7% of the time out of range, which was significantly less compared to all other methods.

Conclusion

Cooling with water-circulating blankets, gel-pads and intravascular cooling is more efficient compared to conventional cooling and air-circulating blankets. The intravascular cooling system is most reliable to maintain a stable temperature.

Therapeutic hypothermia for global and focal ischemic brain injury--a cool way to improve neurologic outcomes

BACKGROUND

Therapeutic hypothermia (TH) has been employed as a neuroprotective strategy for a wide array of clinical problems since the late 1940s. Animal studies have determined that the neuroprotective effect of hypothermia is pleiotropic, impacting many steps in both the ischemic cascade and reperfusion injury. Interest in the neuroprotective effects of TH for ischemic brain injury has been resurgent, fueled by both recent positive and negative clinical trials. A review of preclinical and clinical reports on TH in adult patients is provided in this article.

REVIEW SUMMARY

Animal data and several large clinical studies of mild to moderate TH (32 degrees C-34 degrees C) for global cerebral ischemia describe favorable neurologic outcomes, with few adverse effects. However, clinical implementation for global ischemia remains poor. Some animal data support a role for TH in focal cerebral ischemia, if instituted soon after the onset of ischemia, and in the setting of reperfusion. Clinical studies of TH for focal cerebral ischemia have so far been equivocal. The available data suggest that, despite sharing some common components in the ischemic cascade, focal and global cerebral ischemia are pathophysiologically disparate, and may respond to different neuroprotective strategies.

CONCLUSION

TH is a safe, effective neuroprotective strategy for global cerebral ischemia. Because of the neuroprotective efficacy of TH in adult comatose survivors of cardiac arrest, neurologists should advocate the implementation of this strategy. TH for focal ischemia is a promising therapeutic option, but requires more basic and clinical investigation.

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.

Intranasal selective brain cooling in pigs

BACKGROUND

Special clinical situations where general hypothermia cannot be recommended but can be a useful treatment demand a new approach, selective brain cooling. The purpose of this study was to selectively cool the brain with cold saline circulating in balloon catheters introduced into the nasal cavity in pigs.

MATERIAL AND METHODS

Twelve anaesthetised pigs were subjected to selective cerebral cooling for a period of 6 h. Cerebral temperature was lowered by means of bilaterally introduced nasal balloon catheters perfused with saline cooled by a heat exchanger to 8-10 degrees C. Brain temperature was measured in both cerebral hemispheres. Body temperature was measured in rectum, oesophagus and the right atrium. The pigs were normoventilated and haemodynamic variables were measured continuously. Acid-base and electrolyte status was measured hourly.

RESULTS

Cerebral hypothermia was induced rapidly and within the first 20 min of cooling cerebral temperature was lowered from 38.1+/-0.6 degrees C by a mean of 2.8+/-0.6 to 35.3+/-0.6 degrees C. Cooling was maintained for 6 h and the final brain temperature was 34.7+/-0.9 degrees C. Concomitantly, the body temperature, as reflected by oesophageal temperature was decreased from 38.3+/-0.5 to 36.6+/-0.9 degrees C. No circulatory or metabolic disturbances were noted.

CONCLUSIONS

Inducing selective brain hypothermia with cold saline via nasal balloon catheters can effectively be accomplished in pigs, with no major disturbances in systemic circulation or physiological variables. The temperature gradients between brain and body can be maintained for at least 6 h.

Fever management practices of neuroscience nurses: national and regional perspectives

Neuroscience patients with fever may have worse outcomes than those who are afebrile. However, neuroscience nurses who encounter this common problem face a translational gap between patient-outcomes research and bedside practice because there is no current evidence-based standard of care for fever management of the neurologically vulnerable patient. The aim of this study was to determine if there are trends in national practices for fever and hyperthermia management of the neurologically vulnerable patient. A 15-item mailed questionnaire was used to determine national and regional trends in fever and hyperthermia management and decision making by neuroscience nurses. Members of the American Association of Neuroscience Nurses were surveyed (N = 1,225) and returned 328 usable surveys. Fewer than 20% of respondents reported having an explicit fever management protocol in place for neurologic patients, and 12.5% reported having a nonspecific patient protocol available for fever management. Several clear and consistent patterns in interventions for fever and hyperthermia management were seen nationally, including acetaminophen administration at a dose of 650 mg every 4 hours, ice packs, water cooling blankets, and tepid bathing. However, regional differences were seen in intervention choices and initial temperature to treat.

Fever control and its impact on outcomes: what is the evidence?

Fever is common in a variety of neurological disorders. There is abundant experimental evidence suggesting that fever leads to, or exacerbates, neuronal injury in conditions such as cerebral ischemia and traumatic brain injury. However, conclusive evidence linking control of fever to improved outcomes is lacking. It has been difficult to design studies looking at the impact of fever control on outcome, in part because traditional methods of fever control are ineffective. Recently, several new devices to control temperature have become available. These devices appear to be more effective than conventional means and might allow us to design studies that definitively answer the question: "Does controlling fever improve outcome?"

The endovascular operating room as an extension of the intensive care unit: changing strategies in the management of neurovascular disease

Technological advances within the field of endovascular neurosurgery have influenced the management of the neurovascular patient within the intensive care unit (ICU). The endovascular operating room has, in fact, become an extension of the ICU in certain cases. Given the rapid development of new endovascular technologies, it is more important than ever for neurosurgeons to remain intimately involved with the care of their patients within the ICU. This article offers an overview of the evolution in ICU management of neurovascular disease and provides a framework for the incorporation of the endovascular operating room in the intensive care management of patients with this disease.

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.

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.

Body temperature management after severe traumatic brain injury: methods and protocols used in the United Kingdom and Ireland

OBJECTIVE

To establish whether there is consensus in the management of body temperature in patients with severe traumatic brain injury (TBI) admitted to hospitals in the United Kingdom and Ireland for neurosurgical intensive care.

METHODS

Permission was granted from the Society of British Neurosurgeons (SBNS) and the Local Research Ethics Committee to undertake the survey. A senior member of nursing staff from all adult neurosurgical units, excluding our own, was contacted by telephone.

RESULTS

All 33 adult neurosurgical centres participated. Six units had a formal written protocol for the management of body temperature. For the remainder (27 units), interest was expressed in a protocol for temperature management particularly for those patients with intractable hyperthermia/fever. Administration of the antipyretic paracetamol was the most common 'first-line' treatment (13 units). Other 'first-line' methods were: circulating air-cooling blankets (9 units), water-filled cooling blankets (6 units), tepid sponging or wet soaks (2 units), convection fans (2 units) and administration of cold fluids via the gut or circulation (1 unit). When 'first-line' methods failed to bring about a fall in temperature, different combinations of these methods were used.

CONCLUSIONS

From this survey, it is evident that there is no consensus in the approach to temperature management in neurosurgical intensive care patients with severe TBI. Review and rationalisation of systems of care may be required in an effort to develop evidence-based nationwide guidelines.

Induction of hypothermia in patients with various types of neurologic injury with use of large volumes of ice-cold intravenous fluid

OBJECTIVE

Mounting evidence suggests that mild to moderate hypothermia can mitigate neurologic and myocardial injury. The speed of induction appears to be a key factor in determining its efficacy. However, even when the fastest currently available cooling techniques are used, reaching target temperatures takes at least 2 hrs and usually longer. We hypothesized that infusion of refrigerated fluids could be a safe accessory method to increase cooling speed.

DESIGN

Prospective intervention study.

SETTING

University teaching hospital.

PATIENTS

One hundred thirty-four patients with various types of neurologic injury (postanoxic encephalopathy, subarachnoid hemorrhage, or traumatic brain injury).

MEASUREMENTS AND MAIN RESULTS

Hypothermia was induced in 134 patients with various types of neurologic injury, by means ice-water cooling blankets and infusion of refrigerated (4 degrees C) saline (110 patients) or saline and colloids (24 patients). An average volume of 2340 +/- 890 mL of refrigerated fluids was infused in 50 mins. Core temperatures decreased from 36.9 +/- 1.9 degrees C to 34.6 +/- 1.5 degrees C at t = 30 mins and to 32.9 +/- 0.9 degrees C at t = 60 mins (target temperature: 32 degrees C-33 degrees C). Monitoring of blood pressure, heart rhythm, central venous pressure, blood gasses, electrolyte and glucose levels, and platelet and white blood cell count revealed no additional adverse effects. Mean arterial pressure increased by 15 mm Hg, with larger increases in blood pressure occurring in hemodynamically unstable patients. No patient developed pulmonary edema.

CONCLUSIONS

Induction of hypothermia by means of cold-fluid infusion combined with ice-water cooling blankets is safe, efficacious, and quick. Because the speed of cooling is important to increase its protective effects, we recommend that cold-fluid infusion be used in all patients treated with induced hypothermia. This should be combined with another method to safely and accurately maintain hypothermia once target temperatures have been reached.

Treatment of intracerebral haemorrhage

Apart from management in a specialised stroke or neurological intensive care unit, until very recently no specific therapies improved outcome after intracerebral haemorrhage (ICH). In a recent phase II trial, recombinant activated factor VII (eptacog alfa) reduced haematoma expansion, mortality, and disability when given within 4 h of ICH onset; a phase III trial (the FAST trial) is now in progress. Ventilatory support, blood-pressure reduction, intracranial-pressure monitoring, osmotherapy, fever control, seizure prophylaxis, and nutritional supplementation are the cornerstones of supportive care in intensive care units. Ventricular drainage should be considered in all stuporous or comatose patients with intraventricular haemorrhage and acute hydrocephalus. Given the lack of benefit seen in a the recent STICH trial, emergency surgical evacuation within 72 h of onset should be reserved for patients with large (>3 cm) cerebellar haemorrhages, or those with large lobar haemorrhages, substantial mass effect, and rapidly deteriorating condition.

Comparing the effectiveness of two types of cooling blankets for febrile patients

A randomized controlled trial was conducted to compare the effectiveness of airflow- and waterflow-cooling blankets for febrile patients in intensive care unit. More patients in the airflow than in the waterflow-cooling blanket group reached the desired temperature of <38 degrees C at the end of 8h (94.1 versus 60.0%, chi2=2.86, P=0.047). Patients in the airflow blanket group also took less time than those in the waterflow blanket group to achieve the desired temperature (3.1 and 5.7h, respectively, U=2.00, P<0.001). These findings suggest that the airflow blanket is the cooling blanket of choice for febrile patients when external cooling is needed.