Hypothermia in the hospital phase at 32-34 ° C improves neurological outcome in patients resuscitated after ventricular fibrillation out of the hospital environment. In a normal brain hypothermia reduces the cerebral metabolic rate by 6% for each degree of reduction in temperature above 28 ° C. Mild hypothermia can also suppress some chemical reactions post reperfusion, including the production of free radicals, release of excitatory amino acids and calcium release, leading to mitochondrial damage and apoptosis. In addition to these potential benefits hypothermia may also have adverse effects such as arrhythmias, infections and coagulopathies. Induced hypothermia in the pre-hospital phase can result in a better performance compared to the one set only at the hospital.
This study randomized 1364 patients seen by cardiac arrest out of the hospital with rapid intravenous infusion of 2 liters of saline at 4 ° C with sedation and neuromuscular blockade versus conventional treatment. The primary end point was survival and neurological status at discharge. Survival was similar between both groups for both patients with ventricular fibrillation at baseline (62.7 versus 64.3 %, p = 0.69 ) and for those with a different rhythm to ventricular fibrillation (19.2 versus 16.3%). The intervention did not improve neurologic status at discharge. Patients receiving an infusion of saline at 4 ° C showed a higher incidence of new cardiac arrest (26 versus 21 %, P = 0.008).
Conclusion:
Pre-hospital hypothermia does not improve survival or neurologic outcome in patients with extra- hospital cardiac arrest. It was a higher incidence of new cardiac arrest in the hypothermia branch.
Francis Kim
2013-11-17
Original title: Randomized Clinical Trial of Pre-hospital Induction of Mild Hypothermia in Out-of-Hospital Cardiac Arrest Patients Using a Rapid Infusion of 4oC Normal Saline
