European society of intensive care medicine study of therapeutic hypothermia (32-35 °C) for intracranial pressure reduction after traumatic brain injury (the Eurotherm3235Trial)

[Increased intracranial pressure and brain edema]

In primary and secondary brain diseases, increasing volumes of the three compartments of brain tissue, cerebrospinal fluid, or blood lead to a critical increase in intracranial pressure (ICP). A rising ICP is associated with typical clinical symptoms; however, during analgosedation it can only be detected by invasive ICP monitoring. Other neuromonitoring procedures are not as effective as ICP monitoring; they reflect the ICP changes and their complications by other metabolic and oxygenation parameters. The most relevant parameter for brain perfusion is cerebral perfusion pressure (CPP), which is calculated as the difference between the middle arterial pressure (MAP) and the ICP. A mixed body of evidence exists for the different ICP-reducing treatment measures, such as hyperventilation, hyperosmolar substances, hypothermia, glucocorticosteroids, CSF drainage, and decompressive surgery.

Study of therapeutic hypothermia (32 to 35°C) for intracranial pressure reduction after traumatic brain injury (the Eurotherm3235Trial): outcome of the pilot phase of the trial

Background

Clinical trials in traumatic brain injury (TBI) are challenging. Previous trials of complex interventions were conducted in high-income countries, reported long lead times for site setup and low screened-to-recruitment rates.

In this report we evaluate the internal pilot phase of an international, multicentre TBI trial of a complex intervention to assess: design and implementation of an online case report form; feasibility of recruitment (sites and patients); feasibility and effectiveness of delivery of the protocol.

Methods

All aspects of the pilot phase of the trial were conducted as for the main trial. The pilot phase had oversight by independent Steering and Data Monitoring committees.

Results

Forty sites across 12 countries gained ethical approval. Thirty seven of 40 sites were initiated for recruitment. Of these, 29 had screened patients and 21 randomized at least one patient. Lead times to ethics approval (6.8 weeks), hospital approval (18 weeks), interest to set up (61 weeks), set up to screening (11 weeks), and set up to randomization (31.6 weeks) are comparable with other international trials. Sixteen per cent of screened patients were eligible. We found 88% compliance rate with trial protocol.

Conclusion

The pilot data demonstrated good feasibility for this large international multicentre randomized controlled trial of hypothermia to control intracranial pressure. The sample size was reduced to 600 patients because of homogeneity of the patient group and we showed an optimized cooling intervention could be delivered.

Trial registration

Current Controlled Trials: ISRCTN34555414.

Effect of neuroprotective therapies (hypothermia and cyclosporine a) on dopamine-induced apoptosis in human neuronal SH-SY5Y cells

INTRODUCTION

This study aimed to evaluate the effect of hypothermia and CyA on neuronal survival after induced injury in a neuronal model.

METHODS

Human neuroblastoma SH-SY5Y cells were seeded and allowed to grow. To determine whether lower temperatures protect from dopamine-induced apoptosis, cells were treated with dopamine at 100 µM, at 300 µM or without dopamine and incubated at 32 °C or 37 °C for 24 hours. To assess the effect of CyA, cells were pre-incubated with CyA at 37 °C and after dopamine was added.

RESULTS

After 24 hours of incubation at 37 °C, 100 µM and 300 µM dopamine induced 42% (SD = 21) and 58% (SD = 7.9) apoptotic SH-SY5 cells, respectively. In cultures at 32 °C dopamine-induced apoptosis could be reversed by hypothermia [7% (SD = 1.4) and 3.45% (SD = 1.1) for 100 µM and 300 µM, respectively], similar to levels obtained in non-treated cells [2.4% (SD = 1.5)]. Cyclosporine A treatment did not render the expected result, since CyA-pre-treated cells and SH-SY5Y cells showed higher levels of apoptosis than those observed with dopamine alone

CONCLUSIONS

Hypothermia has a marked protective effect against apoptotic cell death induced by dopamine in a human neuroblastic cell line. The neuroprotective effect of CyA described with other apoptotic cell death stimuli was not demonstrated with our experimental conditions.

Hypothermia in neurocritical care

Hypothermia has long been recognized as an effective therapy for acute neurologic injury. Recent advances in bedside technology and greater understanding of thermoregulatory mechanisms have made this therapy readily available at the bedside. Critical care management of the hypothermic patient can be divided into 3 phases: induction, maintenance, and rewarming. Each phase has known complications that require careful monitoring. At present, hypothermia has only been shown to be an effective neuroprotective therapy in cardiac arrest survivors. The primary use of hypothermia in the neurocritical care unit is to treat increased intracranial pressure.

[Increased intracranial pressure and brain edema]

In primary and secondary brain diseases, increasing volumes of the three compartments of brain tissue, cerebrospinal fluid, or blood lead to a critical increase in intracranial pressure (ICP). A rising ICP is associated with typical clinical symptoms; however, during analgosedation it can only be detected by invasive ICP monitoring. Other neuromonitoring procedures are not as effective as ICP monitoring; they reflect the ICP changes and their complications by other metabolic and oxygenation parameters. The most relevant parameter for brain perfusion is cerebral perfusion pressure (CPP), which is calculated as the difference between the middle arterial pressure (MAP) and the ICP. A mixed body of evidence exists for the different ICP-reducing treatment measures, such as hyperventilation, hyperosmolar substances, hypothermia, glucocorticosteroids, CSF drainage, and decompressive surgery.

Deep hypothermia protects against acute hypoxia in vivo in rats: a mechanism related to the attenuation of oxidative stress

There is growing interest in using hypothermia to prevent hypoxic damage in clinical and experimental models, although the mechanisms regulated by hypothermia are still unclear. As reactive oxygen and nitrogen species are the main factors causing cellular damage, our objective was to study the scope of hypothermia in preventing hypoxia-induced oxidative damage. We analysed systemic and hepatic indicators of oxidative stress after an acute hypoxic insult (10% oxygen in breathing air) in normothermic (37°C body temperature) and hypothermic conditions (22°C) in rats. Exposure to hypoxia resulted in tissue damage (aspartate aminotransferase increased from 54.6 ± 6.9 U l(-1) in control animals to 116 ± 1.9 U l(-1) in hypoxia, and alanine aminotransferase increased from 19 ± 0.8 to 34 ± 2.9 U l(-1)), oxidative stress (nitric oxide metabolites increased from 10.8 ± 0.4 μM in control rats to 23 ± 2.7 μM in hypoxia, and thiobarbituric reactive substances increased from 3.3 ± 0.2 to 5.9 ± 0.4 nm) and antioxidant consumption (reduced/oxidized glutathione ratio changed from 9.8 ± 0.3 to 6.8 ± 0.3). In contrast, when hypothermia was applied prior to hypoxia, the situation was reversed, with a reduction in aspartate aminotransferase (from 116 ± 1.9 in hypoxic animals to 63 ± 7.8 U l(-1) in animals exposed to hypothermia followed by hypoxia), alanine aminotransferase (from 34 ± 2.9 to 19 ± 0.9 U l(-1)), oxidative stress (nitric oxide metabolites decreased from 23 ± 2.7 to 17.8 ± 1.9 μM and thiobarbituric acid-reactive substances decreased from 5.9 ± 0.4 to 4.3 ± 0.2 nm) and antioxidant preservation (reduced/oxidized glutathione ratio changed from 6.8 ± 0.3 to 11.1 ± 0.1). Hypoxia induced a decrease in liver enzymatic antioxidant activities even during hypothermia. Both treatments, hypoxia and hypothermia, produced a similar increase in hepatic caspase-3 activity. In conclusion, hypothermia prevented the tissue damage and oxidative stress elicited by hypoxia. Our results provide new evidence concerning the protective mechanism of hypothermia in vivo.

Cooling in intracerebral hemorrhage (CINCH) trial: protocol of a randomized German-Austrian clinical trial

BACKGROUND

Intracerebral hemorrhage accounts for up to 15% of all strokes and is frequently associated with poor functional outcome and high mortality. So far, there is no clear evidence for a specific therapy, apart from general stroke unit or neurointensive care and management of secondary complications. Promising experimental and pilot clinical data support the use of therapeutic hypothermia after intracerebral hemorrhage.

AIMS

The study aims to determine if therapeutic hypothermia improves survival rates and reduces cerebral lesion volume after large intracerebral hemorrhage compared with conventional treatment.

MATERIAL AND METHODS

The Cooling in IntraCerebral Hemorrhage trial is a prospective, multicenter, interventional, randomized, parallel, two-arm (1 : 1) phase II trial with blinded end-point adjudication. Enrolment: 50 patients (age: 18 to 65 years) with large (25 to 64 ml on cranial computertomography), primary intracerebral hemorrhage of the basal ganglia or thalamus within 6 to 18 h after symptom onset are randomly allocated to therapeutic hypothermia for eight-days or conventional temperature management. In the therapeutic hypothermia group, a target temperature of 35.0°C is achieved by endovascular catheters and followed by slow controlled rewarming. Data analysis is based on the intent-to-treat population. The primary outcome measure of the study is the development in total lesion volume on cranial computertomography (intracerebral hemorrhage plus perihemorrhagic edema on day 8 ± 0.5 and day 1 ± 0.5 after intracerebral hemorrhage) and the mortality after 30 days. Secondary end-points are the in-hospital mortality, mortality, and functional outcome (modified Rankin Scale and Barthel-Index) after 90 and 180 days. Safety measures include any adverse events associated with therapeutic hypothermia.

DISCUSSION

In the face of a lack of evidence-based therapies for patients with large intracerebral hemorrhage, new promising approaches are desperately needed, but need evaluation in randomized controlled trials.

CONCLUSION

The results of Cooling in IntraCerebral Hemorrhage trial are believed to directly influence future therapy of large intracerebral hemorrhage.

Hypothermia for acute brain injury--mechanisms and practical aspects

Hypothermia is widely accepted as the gold-standard method by which the body can protect the brain. Therapeutic cooling--or targeted temperature management (TTM)--is increasingly being used to prevent secondary brain injury in patients admitted to the emergency department and intensive care unit. Rapid cooling to 33 °C for 24 h is considered the standard of care for minimizing neurological injury after cardiac arrest, mild-to-moderate hypothermia (33-35 °C) can be used as an effective component of multimodal therapy for patients with elevated intracranial pressure, and advanced cooling technology can control fever in patients who have experienced trauma, haemorrhagic stroke, or other forms of severe brain injury. However, the practical application of therapeutic hypothermia is not trivial, and the treatment carries risks. Development of clinical management protocols that focus on detection and control of shivering and minimize the risk of other potential complications of TTM will be essential to maximize the benefits of this emerging therapeutic modality. This Review provides an overview of the potential neuroprotective mechanisms of hypothermia, practical considerations for the application of TTM, and disease-specific evidence for the use of this therapy in patients with acute brain injuries.

Decompressive craniectomy – friend or foe?

Decompressive craniectomy (DC) is the surgical management removing part of the skull vault over a swollen brain used to treat elevated intracranial pressure that is unresponsive to maximal medical therapy. The commonest indication for DC is traumatic brain injury (TBI) or middle cerebral artery (MCA) infarction, though DC has been reported to have been used for treatment of aneurysmal subarachnoid haemorrhage and venous infarction. Despite an increasing number of reports supportive of DC, the controversy over the suitability of the procedure and criteria for patient selection remains unresolved. Although the majority of published studies are retrospective, the recent publication of several randomised prospective studies prompts a re-evaluation of the use of DC. We review the literature concerning the pathophysiology, indication, surgical techniques and timing, complications and long-term effects of DC (including reversal with cranioplasty), in order to rationalise its use. We conclude that at the time of this review, though we cannot support the routine use of DC in TBI or MCA stroke, there is evidence that early and aggressive use of DC in TBI patients with intracranial haematomas or younger malignant MCA stroke patients may improve outcome. Though the results of the DECRA trial suggest that primary DC may worsen outcome, the decision to perform DC after diffuse TBI is still individualised. We await the results of the RESCUEicp trial to ascertain whether an evidence-based protocol for its use can be agreed in the future.

Early hospital care of severe traumatic brain injury

Head injury is one of the major causes of trauma-related morbidity and mortality in all age groups in the United Kingdom, and anaesthetists encounter this problem in many areas of their work. Despite a better understanding of the pathophysiological processes following traumatic brain injury and a wealth of research, there is currently no specific treatment. Outcome remains dependant on basic clinical care: management of the patient's airway with particular attention to preventing hypoxia; avoidance of the extremes of lung ventilation; and the maintenance of adequate cerebral perfusion, in an attempt to avoid exacerbating any secondary injury. Hypertonic fluids show promise in the management of patients with raised intracranial pressure. Computed tomography scanning has had a major impact on the early identification of lesions amenable to surgery, and recent guidelines have rationalised its use in those with less severe injuries. Within critical care, the importance of controlling blood glucose is becoming clearer, along with the potential beneficial effects of hyperoxia. The major improvement in outcome reflects the use of protocols to guide resuscitation, investigation and treatment and the role of specialist neurosciences centres in caring for these patients. Finally, certain groups are now recognised as being at greater risk, in particular the elderly, anticoagulated patient.