Skrifvars MB, Soreide E, Sawyer KN, et al. - Researchers examined the links between ischemia and hypothermia duration, ie, the hypothermic to ischemic ratio (H/I ratio), with mortality among patients involved in a trial on two durations of targeted temperature management (TTM) at 33°C. In the TTH48 trial, 24 and 48 hours of TTM was compared among patients following cardiac arrest. They computed hypothermia time from the return of spontaneous circulation (ROSC) until the patient reached 37°C following TTM and the ischemic time from CA to ROSC. There were 338 patients in total. It was shown in a Cox regression model incorporating factors related to outcome in univariate analysis that the outcome was significantly predicted by logarithmically transformed H/I ratio. After removing an outlier, no interaction was evident between time to ROSC and intervention group or hypothermia duration in quartiles with death. Overall, experts found no consistent proof of a modification of the effect of TTM depending on ischemia duration.