SAN FRANCISCO — Therapeutic hypothermia after cardiac arrest appears to be of particular benefit in patients with ventricular fibrillation and those with a short duration of circulatory arrest, according to a poster presented by Dr. Mauro Oddo at the annual congress of the Society of Critical Care Medicine.
In the retrospective study of 109 consecutive patients admitted for out-of-hospital cardiac arrest, a significantly larger proportion of patients treated with hypothermia were able to return home and live independently than of those treated with normothermia.
Among 86 patients admitted with ventricular fibrillation (VF) as the initial rhythm, 24 of 43 (56%) treated with standard postresuscitation care together with hypothermia achieved this outcome, compared with 11 of 43 (26%) treated only with standard postresuscitation care.
The induced hypothermia was mild, wrote Dr. Oddo and his colleagues from University Hospital, Lausanne, Switzerland. The cooling process was external, involving ice bags and a cooling mattress to achieve a target internal temperature of 33° C for 24 hours. Outcomes for the 23 patients admitted with non-VF rhythms tended to be very poor whether or not they were treated with hypothermia. Only three of these patients survived. The two patients treated with hypothermia achieved total recovery, and the one who received only standard treatment was left with severe disability. This trend was not statistically significant.
Hypothermia appeared to provide significant benefit to patients in shock. Of the 17 patients admitted with shock and treated with hypothermia, 5 (29%) were able to return home and live independently, compared with none of the 14 patients in shock who were treated with normothermia.
A multivariate regression analysis revealed two independent predictors of good outcome: shorter time from collapse to return of spontaneous circulation (ROSC) and the application of hypothermia. The model predicted that the greatest benefit of hypothermia would be seen in patients whose time to ROSC was relatively short—10–30 minutes.
Robert Finn