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

Human cord blood transplantation in a neonatal rat model of hypoxic-ischemic brain damage: functional outcome related to neuroprotection in the striatum

Human umbilical cord blood mononuclear cells (HUCB) have been shown to have a therapeutic role in different models of central nervous system (CNS) damage, including stroke. We evaluated the possible therapeutic potential of HUCB in P7 rats submitted to the Rice-Vannucci model of neonatal hypoxic-ischemic (HI) brain damage. Our results demonstrated that intraperitoneal transplantation of HUCB, 3 h after the HI insult, resulted in better performance in two developmental sensorimotor reflexes, in the first week after the injury. We also showed a neuroprotective effect in the striatum, and a decrease in the number of activated microglial cells in the cerebral cortex of treated animals. We suggest that HUCB transplantation might rescue striatal neurons from cell death after a neonatal HI injury resulting in better functional recovery.

Hypothermia reduces perihemorrhagic edema after intracerebral hemorrhage

BACKGROUND AND PURPOSE

The prognosis of spontaneous intracerebral hemorrhage (sICH) is poor because of the mass effect arising from the hematoma and the associated peri-hemorrhagic edema, leading to increased intracranial pressure. Because the efficacy of surgical and anti-edematous treatment strategies is limited, we investigated the effects of mild induced hypothermia in patients with large sICH.

METHODS

Twelve patients with supratentorial sICH >25 mL were treated by hypothermia of 35 degrees C for 10 days. Evolution of hematoma volume and perifocal edema was measured by cranial CT. Functional outcome was assessed after 90 days. These patients were compared to patients (n=25; inclusion criteria: sICH volume >25 mL, no acute restriction of medical therapy on admission) from the local hemorrhage data bank (n=312). Side effects of hypothermia were analyzed.

RESULTS

All patients from both groups needed mechanical ventilation and were treated in a neurocritical care unit. All hypothermic patients (mean age, 60+/-10 years) survived until day 90, whereas 7 patients died in the control group (mean age, 67+/-7 years). Absolute hematoma size on admission was 58+/-29 mL (hypothermia) compared to 57+/-31 mL (control). In the hypothermia group, edema volume remained stable during 14 days (day 1, 53+/-43 mL; day 14, 57+/-45 mL), whereas edema significantly increased in the control group from 40+/-28 mL (day 1) to 88+/-47 mL (day 14). ICH continuously dissolved in both groups. Pneumonia rate was 100% in the hypothermia group and 76% in controls (P=0.08). No significant side effects of hypothermia were observed.

CONCLUSIONS

Hypothermia prevented the increase of peri-hemorrhagic edema in patients with large sICH.

A systematic performance evaluation of brain and body temperature sensors using ultra-stable temperature references

The impact of a rise in the temperature of the human brain in patients who have suffered cerebral damage is not completely understood. Current studies are ambiguous; some show that a high brain temperature, and others a low brain temperature, is an indicator of poor prognosis. The reported effect is often very subtle, at the <0.5 degrees C level, and this may be due to the performance, or even the location of the temperature sensor. This study investigates the first of these issues, i.e. the performance of the sensor. Here performance validation is undertaken for three commonly used temperature sensors for brain and body temperature measurement, using ultra-stable temperature references. At body temperature all three sensor types performed within manufacturer's specifications. Given that only a small number of temperature sensors were tested, the indication is that, provided the sensors are located correctly, the small observed differences in temperature are real - though the issue of clinical significance is still to be addressed.

The role of mild hypothermia in air embolism-induced acute lung injury

BACKGROUND

Mild hypothermia has become an important treatment for ischemic brain injury. However, the role of mild hypothermia in air embolism-induced lung injury has not been explored. In this study, we investigated whether treatment with mild hypothermia before and synchronous with air infusion can attenuate acute lung injury induced by air embolism.

METHODS

In this rat model study (Sprague-Dawley rats), pulmonary air embolism was induced by venous infusion of air at a rate of 25 microL/min for 40 minutes. Control animals received no air infusion. The rats were randomly assigned to 2 control groups of normothermia (37 degrees C) and mild hypothermia (34 degrees C) and 3 air embolism groups of mild hypothermia induced before air infusion, normothermia with air infusion, and mild hypothermia induced synchronous with air infusion. At the end of the experiment, the variables of lung injury were assessed.

RESULTS

Air infusion elicited a significant increase in lung wet/dry weight ratio and protein, lactate dehydrogenase, and tumor necrosis factor-alpha concentration of the bronchoalveolar lavage fluid. Myeloperoxidase activity, neutrophil infiltration, and interstitial edema in lung tissue were also significantly increased. In addition, nuclear factor-kappaB activity was significantly increased in the lungs. Treatment with mild hypothermia before air infusion reduced increases in these variables, whereas mild hypothermia synchronous with air infusion had no significant effect on them.

CONCLUSIONS

Our study suggests that mild hypothermia before air infusion decreases air embolism-induced acute lung injury. The protective mechanism seems to be the inhibition of inflammation.

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 &lt; .001). AFC patients had higher rates of hyperglycemia (P &lt; .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.

Resuscitation center designation: recommendations for emergency medical services practices

Regionalization of medical resources by designating specialty receiving centers, such as trauma and stroke centers, within emergency medical services (EMS) systems is intended to ensure the highest-quality patient care in the most efficient and fiscally responsible fashion. Significant advances in the past decade such as induction of therapeutic hypothermia following resuscitation from cardiac arrest and a time-driven, algorithmic approach to management of septic patients have created compelling arguments for similar designation for specialized resuscitative interventions. Resuscitation of critically ill patients is both labor- and resource-intensive. It can significantly interrupt emergency department (ED) patient throughput. In addition, clinical progress in developing resuscitation techniques is often dependent on the presence of a strong research infrastructure to generate and validate new therapies. It is not feasible for many hospitals to make the commitment to care for large numbers of critically ill patients and the accompanying investigational activities, whether in the prehospital, ED, or inpatient arena. Because of this, the question of whether EMS systems should designate specific hospitals as "resuscitation centers" has now come center stage. Just as EMS systems currently delineate criteria and monitor compliance for trauma, ST-elevation myocardial infarction (STEMI), and stroke centers, strong logic now exists to develop similar standards for resuscitation facilities. Accordingly, this discussion reviews the current applicable trends in resuscitation science and presents a rationale for resuscitation center designation within EMS systems. Potential barriers to the establishment of such centers are discussed and strategies to overcome them are proposed.

Bench-to-bedside review: Hypothermia in traumatic brain injury

Traumatic brain injury remains a major cause of death and severe disability throughout the world. Traumatic brain injury leads to 1,000,000 hospital admissions per annum throughout the European Union. It causes the majority of the 50,000 deaths from road traffic accidents and leaves 10,000 patients severely handicapped: three quarters of these victims are young people. Therapeutic hypothermia has been shown to improve outcome after cardiac arrest, and consequently the European Resuscitation Council and American Heart Association guidelines recommend the use of hypothermia in these patients. Hypothermia is also thought to improve neurological outcome after neonatal birth asphyxia. Cardiac arrest and neonatal asphyxia patient populations present to health care services rapidly and without posing a diagnostic dilemma; therefore, therapeutic systemic hypothermia may be implemented relatively quickly. As a result, hypothermia in these two populations is similar to the laboratory models wherein systemic therapeutic hypothermia is commenced very soon after the injury and has shown so much promise. The need for resuscitation and computerised tomography imaging to confirm the diagnosis in patients with traumatic brain injury is a factor that delays intervention with temperature reduction strategies. Treatments in traumatic brain injury have traditionally focussed on restoring and maintaining adequate brain perfusion, surgically evacuating large haematomas where necessary, and preventing or promptly treating oedema. Brain swelling can be monitored by measuring intracranial pressure (ICP), and in most centres ICP is used to guide treatments and to monitor their success. There is an absence of evidence for the five commonly used treatments for raised ICP and all are potential 'double-edged swords' with significant disadvantages. The use of hypothermia in patients with traumatic brain injury may have beneficial effects in both ICP reduction and possible neuro-protection. This review will focus on the bench-to-bedside evidence that has supported the development of the Eurotherm3235Trial protocol.

Cerebral magnetic resonance biomarkers in neonatal encephalopathy: a meta-analysis

OBJECTIVE

Accurate prediction of neurodevelopmental outcome in neonatal encephalopathy (NE) is important for clinical management and to evaluate neuroprotective therapies. We undertook a meta-analysis of the prognostic accuracy of cerebral magnetic resonance (MR) biomarkers in infants with neonatal encephalopathy.

METHODS

We reviewed all studies that compared an MR biomarker performed during the neonatal period with neurodevelopmental outcome at > or =1 year. We followed standard methods recommended by the Cochrane Diagnostic Accuracy Method group and used a random-effects model for meta-analysis. Summary receiver operating characteristic curves and forest plots of each MR biomarker were calculated. chi(2) tests examined heterogeneity.

RESULTS

Thirty-two studies (860 infants with NE) were included in the meta-analysis. For predicting adverse outcome, conventional MRI during the neonatal period (days 1-30) had a pooled sensitivity of 91% (95% confidence interval [CI]: 87%-94%) and specificity of 51% (95% CI: 45%-58%). Late MRI (days 8-30) had higher sensitivity but lower specificity than early MRI (days 1-7). Proton MR spectroscopy deep gray matter lactate/N-acetyl aspartate (Lac/NAA) peak-area ratio (days 1-30) had 82% overall pooled sensitivity (95% CI: 74%-89%) and 95% specificity (95% CI: 88%-99%). On common study analysis, Lac/NAA had better diagnostic accuracy than conventional MRI performed at any time during neonatal period. The discriminatory powers of the posterior limb of internal capsule sign and brain-water apparent diffusion coefficient were poor.

CONCLUSIONS

Deep gray matter Lac/NAA is the most accurate quantitative MR biomarker within the neonatal period for prediction of neurodevelopmental outcome after NE. Lac/NAA may be useful in early clinical management decisions and counseling parents and as a surrogate end point in clinical trials that evaluate novel neuroprotective therapies.

Successful use of therapeutic hypothermia in an opiate induced out-of-hospital cardiac arrest complicated by severe hypoglycaemia and amphetamine intoxication: a case report

The survival to discharge rate after unwitnessed, non-cardiac out-of-hospital cardiac arrest (OHCA) is dismal. We report the successful use of therapeutic hypothermia in a 26-year old woman with OHCA due to intentional poisoning with heroin, amphetamine and insulin.The cardiac arrest was not witnessed, no bystander CPR was initiated, the time interval from the call to ambulance arrival was 9 minutes and the initial cardiac rhythm was asystole. Eight minutes of advanced cardiac life support resulted in ROSC.Upon hospital admission, the patient's pupils were dilated. Her arterial lactate was 17 mmol/l, base excess -20, pH 6.9 and serum glucose 0.2 mmol/l. During the first 24 hours in the ICU, the patient developed maximally dilated pupils not reacting to light and became increasingly haemodynamically unstable, requiring both inotropic support and massive fluid resuscitation. After 1 week in the ICU, however, she made an uneventful recovery with a Cerebral Performance Category of 1 at hospital discharge and at a follow up examination at 6 months.

CONCLUSION

According to most prognostic factors, the patient had a statistical chance for survival of less than 1%, not taking into account her severe state of hypoglyaemia. We suggest that this case exemplifies the need for more studies on the use of TH in non-coronary causes of OHCA.

The use of systemic hypothermia for the treatment of an acute cervical spinal cord injury in a professional football player

STUDY DESIGN

Case Report.

OBJECTIVE

We will describe the injury and clinical course of an NFL Football player who sustained a complete spinal cord injury and was treated with conventional care in addition to modest systemic hypothermia.

SUMMARY OF BACKGROUND DATA

Systemically induced moderate hypothermia is a potentially neuroprotective intervention in acute spinal cord injury. However, case descriptions of human patients receiving systemic hypothermia after spinal cord injuries are lacking in the literature.

METHODS

Here, we present the case of a National Football League player who sustained a complete (ASIA A) spinal cord injury from a C3/4 fracture dislocation. Moderate systemic hypothermia was instituted immediately after his injury, in addition to standard medical/surgical treatment, including, surgical decompression and intravenous methylprednisolone.

RESULTS

The patient experienced significant and rapid neurologic improvement, and within weeks of his injury was walking with harness assistance. Since that time, the patient has continued to make significant progress in his rehabilitation (now ASIA D).

CONCLUSION

The extent to which this hypothermia contributed to his neurologic recovery is difficult to determine. It is hoped that this case will draw attention to the need for further preclinical and clinical studies to elucidate the role of hypothermia in acute spinal cord injury. Until these studies are completed, it is impossible to advocate for systemic hypothermia as a standard of care.

Small temperature variations alter edaravone-induced neuroprotection of cortical cultures exposed to prolonged hypoxic episodes

BACKGROUND

Edaravone, a free radical scavenger, has been shown to be neuroprotective in vivo and in vitro. However, the impact of small temperature variations on its neuroprotective actions remains unknown.

METHODS

We examined the degree of neuroprotection conferred by various concentrations of edaravone on cortical cultures exposed to prolonged hypoxia (24 h) under three conditions: mild hypothermia (32 degrees C), normothermia (37 degrees C), and mild hyperthermia (39 degrees C). The survival of cortical neurones from E16 Wistar rats (SR) was evaluated using photomicrographs taken before and after exposure to hypoxia.

RESULTS

The mean survival of neurones exposed to hypoxia at normothermia was 14.7 (sem 1.8)%. The addition of 50 microM edaravone significantly improved the mean survival to 40.5 (4.7)%. This improvement was noted at higher doses of edaravone (5 microM < or =) but not at lower doses (< or =500 nM). With mild hypothermia and prolonged hypoxia without edaravone, neuroprotection was significantly improved with a mean survival of 63.0 (5.2)%. This neuroprotective effect was not enhanced with the addition of edaravone, even at the highest dose. Hypoxia-induced neurotoxicity was aggravated by mild hyperthermia as reflected by a mean survival of 9.1 (2.1)%. However, higher concentrations of edaravone inhibited the deleterious effect of mild hyperthermia, thereby demonstrating a significant neuroprotective effect. The survival of neurones subjected to both hyperthermia and edaravone was the same as that of neurones exposed to normothermia and edaravone.

CONCLUSIONS

Temperature is a potential factor in determining whether edaravone confers a neuroprotective effect when applied during prolonged hypoxic insults.

The evidence for hypothermia as a neuroprotectant in traumatic brain injury

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

Favorable influence of subclinical hypothyroidism on the functional outcomes in stroke patients

Subclinical hypothyroidism (SCH) is thought to have an influence on stroke outcomes. However, few reports demonstrate a favorable relationship between the two. We evaluated this association in acute ischemic stroke. From Jan 2005 to June 2008, 756 acute ischemic stroke patients were recruited within seven days of onset. The patients with overt hypothyroidism/hyperthyroidism or other medical conditions that may affect thyroid function were excluded. Thyroid stimulating hormone (TSH) and free thyroxine (FT4) levels were measured within two days. Patients were divided into two groups: the SCH group (TSH > 5.0 microU/mL and normal FT4 levels) and the control group. Stroke outcomes were assessed using two different criteria. In the first outcome model, favorable outcomes [I] were simply defined by modified Rankin Scale (mRS) scores (<or= 1), while the favorable outcomes [II] were defined as follows: a) a mRS score of 0, if the baseline National Institute of Health Stroke Scale (NIHSS) scores were < 8, b) a mRS score of 0 or 1, if the NIHSS scores were 8-14, c) a mRS score 0-2, if the NIHSS scores were >14. The changes in mRS scores and the proportion of patients with favorable outcomes [I] or [II] at the 30(th) and 90(th) day were compared between the two patient groups. Of the 756 patients, 31 (4.1%) were patients with SCH. More patients from the SCH group showed improvement in NIHSS scores on the 30(th) day compared to the control group (48.4% vs. 25.3%, p=.006). In addition, the proportion of patients who exhibited favorable outcomes [I] was significantly higher in the SCH group on the 90(th) day (74.2% vs. 55.3%, p=.027) and that trend was seen as early as the 30(th) day (p=.102). Similarly, the proportion of the patients with favorable outcomes [II] was significantly greater in the SCH group both on the 30(th) (29.0% vs. 14.6%, p=.039) and 90(th) day (58.0% vs. 31.0%, p=.003). We found that acute ischemic stroke patients with SCH at admission were more likely to show favorable functional outcomes than those without SCH. We can suggest preconditioning before the stroke combined with a reduced response to stress as a possible protective mechanism.

Persisting mild hypothermia suppresses hypoxia-inducible factor-1alpha protein synthesis and hypoxia-inducible factor-1-mediated gene expression

The transcription factor hypoxia-inducible factor-1 (HIF-1) plays an essential role in regulating gene expression in response to hypoxia-ischemia. Ischemia causes the tissue not only to be hypoxic but also to be hypothermic because of the hypoperfusion under certain circumstances. On the other hand, the induced hypothermia is one of the most common therapeutic modalities to extend tolerance to hypoxia. Although hypoxia elicits a variety of cellular and systemic responses at different organizational levels in the body, little is known about how hypoxia-induced responses are affected by low temperature. We examined the influence of mild hypothermic conditions (28-32 degrees C) on HIF-1 in both in vitro and in vivo settings. In vitro experiments adopting cultured cells elucidated that hypoxia-induced HIF-1 activation was resistant to 4-h exposure to the low temperature. In contrast, exposure to the low temperature as long as 24 h suppressed HIF-1 activation and the subsequent upregulation of HIF-1 target genes such as VEGF or GLUT-1. HIF-1alpha protein stability in the cell was not affected by hypothermic treatment. Furthermore, intracellular ATP content was reduced under 1% O(2) conditions but was not largely affected by hypothermic treatment. The evidence indicates that reduction of oxygen consumption is not largely involved in suppression of HIF-1. In addition, we demonstrated that HIF-1 DNA-binding activity and HIF-1-dependent gene expressions induced under 10% O(2) atmosphere in mouse brain were not influenced by treatment under 3-h hypothermic temperature but were inhibited under 5-h treatment. On the other hand, we indicated that warming ischemic legs of mice for 24 h preserved HIF-1 activity. In this report we describe for the first time that persisting low temperature significantly reduced HIF-1alpha neosynthesis under hypoxic conditions, leading to a decrease in gene expression for adaptation to hypoxia in both in vitro and in vivo settings.

Management of intracranial pressure

Although intracranial hypertension may arise from diverse pathology, several basic principles remain paramount to understanding its dynamics; however, the management of elevated intracranial pressure (ICP) may be very complex. Initial management of common ICP exacerbants is important, such as addressing venous outflow obstruction with upright midline head positioning and treating agitation and pain with sedation and analgesia. Surgical decompression of mass effect may rapidly improve ICP elevation, but the impact on outcome is unclear. Considerable effort has been put forth to understand the roles of multimodal intensive care monitoring, osmolar therapy, cerebral metabolic suppression, and temperature augmentation in the advanced management of elevated ICP. Establishing a protocol-driven approach to the management of ICP enables the rapid bedside assessment of multiple physiologic variables to implement appropriate treatments, which limit the risk of developing secondary brain injury.

Neurologic complications in non-neurological intensive care units

BACKGROUND

Neurologists are frequently called to evaluate patients in the intensive care units who are not waking up. This often poses a diagnostic and prognostic dilemma.

REVIEW SUMMARY

The initial evaluation starts with abstracting the prehospital and in-hospital history, followed by bedside clinical and neurologic examination to establish a differential diagnosis. The subsequent work-up is based on clinical suspicion where reversible life-threatening causes should be immediately identified. After confirming the diagnosis and implementation of the appropriate medical management, a prompt family meeting and counseling is recommended. The role of neurologists in clinical diagnosis and prognostication of the coma patient, as well as diagnosing brain death is instrumental.

CONCLUSIONS

In this review, we explore a practical systematic approach to patients with decreased level of consciousness. The most common causes of impaired alertness in different non-neurologic critical care units and commonly used prognostication tools are presented. Finally a brief introduction of hypothermia, a novel therapeutic approach is also discussed.

Effects of unilateral decompressive craniectomy on patients with unilateral acute post-traumatic brain swelling after severe traumatic brain injury

Introduction

Acute post-traumatic brain swelling (BS) is one of the pathological forms that need emergent treatment following traumatic brain injury. There is controversy about the effects of craniotomy on acute post-traumatic BS. The aim of the present clinical study was to assess the efficacy of unilateral decompressive craniectomy (DC) or unilateral routine temporoparietal craniectomy on patients with unilateral acute post-traumatic BS.

Methods

Seventy-four patients of unilateral acute post-traumatic BS with midline shifting more than 5 mm were divided randomly into two groups: unilateral DC group (n = 37) and unilateral routine temporoparietal craniectomy group (control group, n = 37). The vital signs, the intracranial pressure (ICP), the Glasgow outcome scale (GOS), the mortality rate and the complications were prospectively analysed.

Results

The mean ICP values of patients in the unilateral DC group at hour 24, hour 48, hour 72 and hour 96 after injury were much lower than those of the control group (15.19 +/- 2.18 mmHg, 16.53 +/- 1.53 mmHg, 15.98 +/- 2.24 mmHg and 13.518 +/- 2.33 mmHg versus 19.95 +/- 2.24 mmHg, 18.32 +/- 1.77 mmHg, 21.05 +/- 2.23 mmHg and 17.68 +/- 1.40 mmHg, respectively). The mortality rates at 1 month after treatment were 27% in the unilateral DC group and 57% in the control group (p = 0.010). Good neurological outcome (GOS Score of 4 to 5) rates 1 year after injury for the groups were 56.8% and 32.4%, respectively (p = 0.035). The incidences of delayed intracranial hematoma and subdural effusion were 21.6% and 10.8% versus 5.4% and 0, respectively (p = 0.041 and 0.040).

Conclusions

Our data suggest that unilateral DC has superiority in lowering ICP, reducing the mortality rate and improving neurological outcomes over unilateral routine temporoparietal craniectomy. However, it increases the incidence of delayed intracranial hematomas and subdural effusion, some of which need secondary surgical intervention. These results provide information important for further large and multicenter clinical trials on the effects of DC in patients with acute post-traumatic BS.

Trial registration

ISRCTN14110527

Hypoxia-induced cell damage is reduced by mild hypothermia and postconditioning with catalase in-vitro: application of an enzyme based oxygen deficiency system

Mild hypothermia and pharmacological postconditioning are widespread therapeutical treatment options that positively influence the clinical outcome after tissue hypoxia. In the study presented, a two-enzyme based in-vitro oxygen deficiency model in combination with cultured HT-1080 fibrosarcoma cells was employed to mimic the in-vivo situation of hypoxia and to evaluate the influence of mild hypothermia and postconditioning with catalase on hypoxia-mediated cell damage. Using the in-vitro oxygen deficiency model, partial pressure of oxygen was rapidly reduced to levels below 5mmHg in the culture media and cells responded with an increased expression of hypoxia inducible factor-1 on protein level. Hypoxia resulted in significant cell rounding and retraction of cytoplasmic cell extensions. Evaluation of cytotoxicity revealed a 3.5-fold increase in lactate dehydrogenase levels which was accompanied by 40-fold elevated levels of hydrogen peroxide. The hypoxia-induced increase of lactate dehydrogenase was 2.5-fold reduced in the hypothermia group, although morphological correlates of cytotoxicity were still visible. Hypothermia did not significantly influence hydrogen peroxide concentrations in the culture media. Pharmacological postconditioning with catalase however dose-dependently decreased hypoxia-induced lactate dehydrogenase release. This cytoprotective effect was accompanied by a dose-dependent, up to 50-fold reduction of hydrogen peroxide concentrations and retention of normal cell morphology. We suggest that the described in-vitro oxygen deficiency model is a convenient and simple culture system for the investigation of cellular and subcellular events associated with oxygen deficiency. Moreover, our in-vitro results imply that catalase postconditioning may be a promising approach to attenuate hypoxia-induced and hydrogen peroxide-mediated cell and tissue damage.

Active cooling in traumatic brain-injured patients: a questionable therapy?

Hypothermia is shown to be beneficial for the outcome after a transient global brain ischaemia through its neuroprotective effect. Whether this is also the case after focal ischaemia, such as following a severe traumatic brain injury (TBI), has been investigated in numerous studies, some of which have shown a tendency towards an improved outcome, whereas others have not been able to demonstrate any beneficial effect. A Cochrane report concluded that the majority of the trials that have already been published have been of low quality, with unclear allocation concealment. If only high-quality trials are considered, TBI patients treated with active cooling were more likely to die, a conclusion supported by a recent high-quality Canadian trial on children. Still, there is a belief that a modified protocol with a shorter time from the accident to the start of active cooling, longer cooling and rewarming time and better control of blood pressure and intracranial pressure would be beneficial for TBI patients. This belief has led to the instigation of new trials in adults and in children, including these types of protocol adjustments. The present review provides a short summary of our present knowledge of the use of active cooling in TBI patients, and presents some tentative explanations as to why active cooling has not been shown to be effective for outcome after TBI. We focus particularly on the compromised circulation of the penumbra zone, which may be further reduced by the stress caused by the difference in thermostat and body temperature and by the hypothermia-induced more frequent use of vasoconstrictors, and by the increased risk of contusional bleedings under hypothermia. We suggest that high fever should be reduced pharmacologically.

Prehospital cooling in cardiac arrest--the next frontier?

Therapeutic hypothermia (TH) in unconscious survivors of out-of-hospital cardiac arrest (OHCA) is now a well-documented part of post-resuscitation care. Implementation of TH into daily clinical practice has been far more successful in the Scandinavian countries than in the rest of the world. Still, many questions remain. One of them is whether prehospital cooling will result in better outcomes.

Prehospital resuscitated cardiac arrest patients: role for induced hypothermia

This article is a support paper for the National Association of EMS Physicians' position paper on induced therapeutic hypothermia in resuscitated cardiac arrest patients. Induced hypothermia is one of the newest treatments aimed at increasing the dismal neurologically intact survival rate for out-of-hospital cardiac arrest patients. Two landmark studies published in 2002 by the New England Journal of Medicine led to the American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care IIa recommendation of cooling unconscious adult patients with return of spontaneous circulation after out-of-hospital cardiac arrest due to ventricular fibrillation to 32 degrees C to 34 degrees C for 12 to 24 hours. Despite many limitations of those studies, the AHA also suggests that this therapy may be beneficial for patients with non-ventricular fibrillation arrests. However, the literature is lacking in answers with regard to the best methods to utilize in cooling patients. While avoiding delay in the initiation of cooling seems logical, the literature is also lacking evidence indicating the ideal time at which to implement cooling. Furthermore, it remains unclear as to which patients may benefit from induced hypothermia. Finally, the literature provides no evidence to support mandating induced hypothermia in the prehospital setting. Given limited prehospital resources, sometimes consisting of only two providers, attention first needs to be given to providing the basic care with the utmost skill. Once the basics are being delivered expertly, consideration can be given to the use of prehospital cooling for the resuscitated cardiac arrest patient in the setting of continued cooling in the hospital.

Intraoperative hypothermia during vascular neurosurgical procedures

Increasing evidence in animal models and clinical trials for stroke, hypoxic encephalopathy for children, and traumatic brain injury have shown that mild hypothermia may attenuate ischemic damage and improve neurological outcome. However, it is less clear if mild intraoperative hypothermia during vascular neurosurgical procedures results in improved outcomes for patients. This review examines the scientific evidence behind hypothermia as a treatment and discusses factors that may be important for the use of this adjuvant technique, including cooling temperature, duration of hypothermia, and rate of rewarming.

Mechanisms of action, physiological effects, and complications of hypothermia

BACKGROUND

Mild to moderate hypothermia (32-35 degrees C) is the first treatment with proven efficacy for postischemic neurological injury. In recent years important insights have been gained into the mechanisms underlying hypothermia's protective effects; in addition, physiological and pathophysiological changes associated with cooling have become better understood.

OBJECTIVE

To discuss hypothermia's mechanisms of action, to review (patho)physiological changes associated with cooling, and to discuss potential side effects.

DESIGN

Review article.

INTERVENTIONS

None.

MAIN RESULTS

A myriad of destructive processes unfold in injured tissue following ischemia-reperfusion. These include excitotoxicty, neuroinflammation, apoptosis, free radical production, seizure activity, blood-brain barrier disruption, blood vessel leakage, cerebral thermopooling, and numerous others. The severity of this destructive cascade determines whether injured cells will survive or die. Hypothermia can inhibit or mitigate all of these mechanisms, while stimulating protective systems such as early gene activation. Hypothermia is also effective in mitigating intracranial hypertension and reducing brain edema. Side effects include immunosuppression with increased infection risk, cold diuresis and hypovolemia, electrolyte disorders, insulin resistance, impaired drug clearance, and mild coagulopathy. Targeted interventions are required to effectively manage these side effects. Hypothermia does not decrease myocardial contractility or induce hypotension if hypovolemia is corrected, and preliminary evidence suggests that it can be safely used in patients with cardiac shock. Cardiac output will decrease due to hypothermia-induced bradycardia, but given that metabolic rate also decreases the balance between supply and demand, is usually maintained or improved. In contrast to deep hypothermia (<or=30 degrees C), moderate hypothermia does not induce arrhythmias; indeed, the evidence suggests that arrhythmias can be prevented and/or more easily treated under hypothermic conditions.

CONCLUSIONS

Therapeutic hypothermia is a highly promising treatment, but the potential side effects need to be properly managed particularly if prolonged treatment periods are required. Understanding the underlying mechanisms, awareness of physiological changes associated with cooling, and prevention of potential side effects are all key factors for its effective clinical usage.

Fever in the critically ill medical patient

Fever, commonly defined by a temperature of >or=38.3 degrees C (101 degrees F), occurs in approximately one half of patients admitted to intensive care units. Fever may be attributed to both infectious and noninfectious causes, and its development in critically ill adult medical patients is associated with an increased risk for death. Although it is widespread and clinically accepted practice to therapeutically lower temperature in patients with hyperthermic syndromes, patients with marked hyperpyrexia, and selected populations such as those with neurologic impairment, it is controversial whether most medical patients with moderate degrees of fever should be treated with antipyretic or direct cooling therapies. Although treatment of fever may improve patient comfort and reduce metabolic demand, fever is a normal adaptive response to infection and its suppression is potentially harmful. Clinical trials specifically comparing fever management strategies in neurologically intact critically ill medical patients are needed.

Hypothermia in multisystem trauma

Exsanguinating hemorrhage is a common clinical feature of multisystem trauma that results in death or severe disability. Cardiovascular collapse resulting from hemorrhage is unresponsive to conventional methods of cardiopulmonary resuscitation. Even when bleeding is controlled rapidly, adequate circulation cannot be restored in time to avoid neurologic consequences that appear after only 5 mins of cerebral ischemia and hypoperfusion. Reperfusion adds further insult to injury. A novel solution to this problem would be to institute a therapy that makes cells and organs more resistant to ischemic injury, thereby extending the time they can tolerate such an insult. Hypothermia can attenuate some effects of ischemia and reperfusion. Accumulating preclinical data demonstrate that hypothermia can be induced safely and rapidly to achieve emergency preservation for resuscitation during lethal hemorrhage. Hypothermia may be an effective therapeutic approach for otherwise lethal traumatic hemorrhage, and a clinical trial to determine its utility is warranted.

Reliability issues in human brain temperature measurement

Introduction

The influence of brain temperature on clinical outcome after severe brain trauma is currently poorly understood. When brain temperature is measured directly, different values between the inside and outside of the head can occur. It is not yet clear if these differences are 'real' or due to measurement error.

Methods

The aim of this study was to assess the performance and measurement uncertainty of body and brain temperature sensors currently in use in neurocritical care. Two organic fixed-point, ultra stable temperature sources were used as the temperature references. Two different types of brain sensor (brain type 1 and brain type 2) and one body type sensor were tested under rigorous laboratory conditions and at the bedside. Measurement uncertainty was calculated using internationally recognised methods.

Results

Average differences between the 26°C reference temperature source and the clinical temperature sensors were +0.11°C (brain type 1), +0.24°C (brain type 2) and -0.15°C (body type), respectively. For the 36°C temperature reference source, average differences between the reference source and clinical thermometers were -0.02°C, +0.09°C and -0.03°C for brain type 1, brain type 2 and body type sensor, respectively. Repeat calibrations the following day confirmed that these results were within the calculated uncertainties. The results of the immersion tests revealed that the reading of the body type sensor was sensitive to position, with differences in temperature of -0.5°C to -1.4°C observed on withdrawing the thermometer from the base of the isothermal environment by 4 cm and 8 cm, respectively. Taking into account all the factors tested during the calibration experiments, the measurement uncertainty of the clinical sensors against the (nominal) 26°C and 36°C temperature reference sources for the brain type 1, brain type 2 and body type sensors were ± 0.18°C, ± 0.10°C and ± 0.12°C respectively.

Conclusions

The results show that brain temperature sensors are fundamentally accurate and the measurements are precise to within 0.1 to 0.2°C. Subtle dissociation between brain and body temperature in excess of 0.1 to 0.2°C is likely to be real. Body temperature sensors need to be secured in position to ensure that measurements are reliable.

Edaravone for the treatment of acute cerebral infarction: role of endothelium-derived nitric oxide and oxidative stress

Thrombolytic therapy is the most effective therapeutic strategy for the prevention of brain injury and reduction of mortality in patients with acute cerebral infarction. A combination of established thrombolytic therapy and effective neuronal protection therapy has more beneficial effects for patients with acute cerebral infarction. Edaravone (chemical name: 3-methyl-1-phenyl-2-pyrazolin-5-one) is a strong, novel scavenger of free radicals. Several lines of evidence have shown that edaravone has preventive effects on brain injury following ischaemia and reperfusion in patients with brain attack. This review focuses on putative mechanisms underlying the beneficial effects of edaravone on the atherosclerotic process in patients with stroke and on the possibility of edaravone-induced extension of the therapeutic time window in patients with acute cerebral infarction.

Hypothermia for traumatic head injury

BACKGROUND

Hypothermia has been used in the treatment of head injury for many years. Encouraging results from small trials and laboratory studies led to renewed interest in the area and some larger trials.

OBJECTIVES

To estimate the effect of mild hypothermia for traumatic head injury on mortality and long-term functional outcome complications.

SEARCH STRATEGY

We searched the Injuries Group Specialised Register, Current Controlled Trials MetaRegister of trials, Zetoc, ISI Web of Science: Science Citation Index Expanded (SCI-EXPANDED) and Conference Proceedings Citation Index-Science (CPCI-S), CENTRAL (The Cochrane Library), MEDLINE and EMBASE. We handsearched conference proceedings and checked reference lists of all relevant articles. The search was last updated in January 2009.

SELECTION CRITERIA

Randomised controlled trials of hypothermia to a maximum of 35 degrees C for at least 12 consecutive hours versus control in patients with any closed traumatic head injury requiring hospitalisation. Two authors independently assessed all trials.

DATA COLLECTION AND ANALYSIS

Data on death, Glasgow Outcome Scale and pneumonia were sought and extracted, either from published material or by contacting the investigators. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for each trial on an intention-to-treat basis.

MAIN RESULTS

We found 23 trials with a total of 1614 randomised patients. Twenty-one trials involving 1587 patients reported deaths. There were fewer deaths in patients treated with hypothermia than in the control group (OR 0.84, 95% CI 0.67 to 1.05). Nine trials with good allocation concealment showed no decrease in the likelihood of death compared with the control group, and this result was not statistically significant (OR 1.08, 95% CI 0.79 to 1.47). Twenty-one trials involving 1587 patients reported data on unfavourable outcomes (death, vegetative state or severe disability). Patients treated with hypothermia were less likely to have an unfavourable outcome than those in the control group (OR 0.76, 95% CI 0.61 to 0.93). Nine trials with good allocation concealment showed patients treated with hypothermia were less likely to have an unfavourable outcome than those in the control group, but the reduction was small and non-significant (OR 0.91, 95% CI 0.69 to 1.20). Hypothermia treatment was associated with a slight increase in the odds of pneumonia (OR 1.31, 95% CI 0.93 to 1.86) but there was a reduction in pneumonia for trials with good allocation concealment (4 trials analysed separately, 294 patients, OR 0.79, 95% CI 0.49 to 1.27) although in both cases the results are not statistically significant.

AUTHORS' CONCLUSIONS

There is no evidence that hypothermia is beneficial in the treatment of head injury. Hypothermia may be effective in reducing death and unfavourable outcomes for traumatic head injured patients, but significant benefit was only found in low quality trials. Low quality trials have a tendency to overestimate the treatment effect. The high quality trials found no decrease in the likelihood of death with hypothermia, but this finding was not statistically significant and could be due to the play of chance. Hypothermia should not be used except in the context of a high quality randomised controlled trial with good allocation concealment.

[Hypothermia for intracranial hypertension]

There is a large body of experimental evidence showing benefits of deliberate mild hypothermia (33-35 degrees C) on the injured brain as well as an improvement of neurological outcome after cardiac arrest in humans. However, the clinical evidence of any benefit of hypothermia following stroke, brain trauma and neonatal asphyxia is still lacking. Controversial results have been published in patients with brain trauma or neonatal asphyxia. Hypothermia can reduce the elevation of intracranial pressure, through mechanisms not completely understood. Hypothermia-induced hypocapnia should have a role on the reduction of intracranial pressure. The temperature target is unknown but no additional benefit was found below 34 degrees C. The duration of deliberate hypothermia for the treatment of elevated intracranial pressure might be at least 48 hours, and the subsequent rewarming period must be very slow to prevent adverse effects.

Commentary: physical approaches for the treatment of epilepsy: electrical and magnetic stimulation and cooling

Physical approaches for the treatment of epilepsy currently under study or development include electrical or magnetic brain stimulators and cooling devices, each of which may be implanted or applied externally. Some devices may stimulate peripheral structures, whereas others may be implanted directly into the brain. Stimulation may be delivered chronically, intermittently, or in response to either manual activation or computer-based detection of events of interest. Physical approaches may therefore ultimately be appropriate for seizure prophylaxis by causing a modification of the underlying substrate, presumably with a reduction in the intrinsic excitability of cerebral structures, or for seizure termination, by interfering with the spontaneous discharge of pathological neuronal networks. Clinical trials of device-based therapies are difficult due to ethical issues surrounding device implantation, problems with blinding, potential carryover effects that may occur in crossover designs if substrate modification occurs, and subject heterogeneity. Unresolved issues in the development of physical treatments include optimization of stimulation parameters, identification of the optimal volume of brain to be stimulated, development of adequate power supplies to stimulate the necessary areas, and a determination that stimulation itself does not promote epileptogenesis or adverse long-term effects on normal brain function.

Cooling combined with immediate or delayed xenon inhalation provides equivalent long-term neuroprotection after neonatal hypoxia-ischemia

Hypothermia (HT) improves outcome after neonatal hypoxia-ischemia. Combination therapy may extend neuroprotection. The noble anesthetic gas xenon (Xe) has an excellent safety profile. We have shown earlier that 3 h of 50% Xe plus HT (32 degrees C) additively gives more protection (72%) than either alone (HT=31.1%, Xe=10.2%). Factors limiting clinical use include high-cost and specialist administration requirements. Thus, combinations of 1 h of 50% Xe were administered concurrently for either the first (1 h(Immediate)Xe) or last (1 h(Delayed)Xe) of 3 h of posthypoxic-ischemic HT as compared with 3 h of 50%Xe/HT to investigate how brief Xe exposure with a delay would affect efficacy. An established neonatal rat hypoxia-ischemia model was used. Serial functional neurologic testing into adulthood was performed, followed by neuropathological examination. Xenon with HT was more effective with longer Xe duration (3 h versus 1 h) (P=0.015). However, 1 h Xe/3 h HT resulted in better neuroprotection than 3 h HT alone (P=0.03), this significant effect was also present with 1 h Xe after a 2-h delay. One (immediate or with a delay) or 3 h Xe also significantly improved motor function (P=0.024). Females had significantly better motor scores than males, but no sex-dependent difference in pathology results. The neuroprotection of short, delayed Xe treatment would allow transport to specialist facilities to receive Xe.

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

BACKGROUND

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

OBJECTIVE

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

DESIGN

Review article.

INTERVENTIONS

None.

MAIN RESULTS

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

CONCLUSIONS

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

[Deleterious role of hyperthermia in neurocritical care]

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