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Original Investigation
Caring for the Critically Ill Patient
December 4, 2018

Effect of Early Sustained Prophylactic Hypothermia on Neurologic Outcomes Among Patients With Severe Traumatic Brain InjuryThe POLAR Randomized Clinical Trial

Author Affiliations
  • 1Australian and New Zealand Intensive Care Research Centre, Monash University, Melbourne, Victoria, Australia
  • 2Departments of Intensive Care, Alfred Hospital, Melbourne, Victoria, Australia
  • 3Irish Critical Care Clinical Trials Network, University College Dublin-Clinical Research Centre at St Vincent’s University Hospital, Dublin, Ireland
  • 4Department of Anaesthesia and Intensive Care Medicine, St Vincent's University Hospital, Dublin, Ireland
  • 5School of Medicine and Medical Sciences, University College Dublin, Dublin, Ireland
  • 6Ambulance Victoria, Melbourne, Victoria, Australia
  • 7School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
  • 8Centre of Excellence in Traumatic Brain Injury Research, Monash University, Melbourne, Victoria, Australia
  • 9Emergency Medicine, Hamad Medical Corporation, Dhueta, Qatar
  • 10Emergency and Trauma Centre, Alfred Hospital, Melbourne, Victoria, Australia
  • 11Service de Réanimation Chirurgicale, Pôle d'Anesthésie et Réanimation Chirurgicale, Centre Hospitalier Universitaire de Besancon, Besançon, France
  • 12Department of Anaesthesia and Intensive Care Medicine, Hôpital de La Cavale Blanche, CHRU de Brest, Brest, France
  • 13UFR de médecine et des sciences de la santé, Université de Bretagne Occidenta, Brest, France
  • 14Department of Critical Care Medicine, Auckland City Hospital, Auckland, New Zealand
  • 15Intensive Care Unit, Royal Melbourne Hospital, Melbourne, Victoria, Australia
  • 16Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
  • 17Queensland Ambulance Service, Brisbane, Queensland, Australia
  • 18Neurosurgery, Alfred Hospital, Melbourne, Victoria, Australia
  • 19Department of Surgery, Monash University, Melbourne, Victoria, Australia
  • 20Department of Surgery, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
  • 21Radiology, Alfred Hospital, Melbourne, Victoria, Australia
  • 22Intensive Care Unit, Royal Perth Hospital, Perth, Western Australia, Australia
JAMA. 2018;320(21):2211-2220. doi:10.1001/jama.2018.17075
Visual Abstract.
Visual Abstract.
Prophylactic Hypothermia and Neurologic Outcomes in Patients With Severe TBI
Prophylactic Hypothermia and Neurologic Outcomes in Patients With Severe TBI
Key Points

Question  Does early prophylactic hypothermia improve long-term neurologic outcomes in patients with severe traumatic brain injury?

Findings  In this randomized clinical trial that included 511 adults, the proportion of patients with favorable neurologic outcomes at 6 months was 48.8% after hypothermia vs 49.1% after normothermia, a difference that was not statistically significant.

Meaning  These findings do not support the use of early prophylactic hypothermia in patients with severe traumatic brain injury.

Abstract

Importance  After severe traumatic brain injury, induction of prophylactic hypothermia has been suggested to be neuroprotective and improve long-term neurologic outcomes.

Objective  To determine the effectiveness of early prophylactic hypothermia compared with normothermic management of patients after severe traumatic brain injury.

Design, Setting, and Participants  The Prophylactic Hypothermia Trial to Lessen Traumatic Brain Injury–Randomized Clinical Trial (POLAR-RCT) was a multicenter randomized trial in 6 countries that recruited 511 patients both out-of-hospital and in emergency departments after severe traumatic brain injury. The first patient was enrolled on December 5, 2010, and the last on November 10, 2017. The final date of follow-up was May 15, 2018.

Interventions  There were 266 patients randomized to the prophylactic hypothermia group and 245 to normothermic management. Prophylactic hypothermia targeted the early induction of hypothermia (33°C-35°C) for at least 72 hours and up to 7 days if intracranial pressures were elevated, followed by gradual rewarming. Normothermia targeted 37°C, using surface-cooling wraps when required. Temperature was managed in both groups for 7 days. All other care was at the discretion of the treating physician.

Main Outcomes and Measures  The primary outcome was favorable neurologic outcomes or independent living (Glasgow Outcome Scale–Extended score, 5-8 [scale range, 1-8]) obtained by blinded assessors 6 months after injury.

Results  Among 511 patients who were randomized, 500 provided ongoing consent (mean age, 34.5 years [SD, 13.4]; 402 men [80.2%]) and 466 completed the primary outcome evaluation. Hypothermia was initiated rapidly after injury (median, 1.8 hours [IQR, 1.0-2.7 hours]) and rewarming occurred slowly (median, 22.5 hours [IQR, 16-27 hours]). Favorable outcomes (Glasgow Outcome Scale–Extended score, 5-8) at 6 months occurred in 117 patients (48.8%) in the hypothermia group and 111 (49.1%) in the normothermia group (risk difference, 0.4% [95% CI, –9.4% to 8.7%]; relative risk with hypothermia, 0.99 [95% CI, 0.82-1.19]; P = .94). In the hypothermia and normothermia groups, the rates of pneumonia were 55.0% vs 51.3%, respectively, and rates of increased intracranial bleeding were 18.1% vs 15.4%, respectively.

Conclusions and Relevance  Among patients with severe traumatic brain injury, early prophylactic hypothermia compared with normothermia did not improve neurologic outcomes at 6 months. These findings do not support the use of early prophylactic hypothermia for patients with severe traumatic brain injury.

Trial Registration  clinicaltrials.gov Identifier: NCT00987688; Anzctr.org.au Identifier: ACTRN12609000764235

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