Profound Hypothermia (<10°C) Compared with Deep Hypothermia (15°C) Improves Neurologic Outcome in Dogs After Two Hoursʼ Circulatory Arrest Induced to Enable Resuscitative Surgery

Deaths from uncontrollable hemorrhage might be prevented by arresting the circulation under protective hypothermia to allow resuscitative surgery to repair these injuries in a bloodless field. We have shown previously that in hemorrhagic shock, circulatory arrest of 60 minutes under deep hypothermia (tympanic membrane temperature, Ttm = 15°C) was the maximum duration of arrest that allowed normal brain recovery. We hypothesize that profound cerebral hypothermia (Ttm < 10°C) could extend the duration of safe circulatory arrest. In pilot experiments, we found that the cardiopulmonary system did not tolerate arrest at a core (esophageal) temperature (Tes) of