Cardiac arrest from accidental hypothermia, a rare condition with potentially excellent neurological outcome, if you treat it right.

86 In this issue Schober et al. report the experience of the University ospital Vienna, Austria, a tertiary referral centre, in the treatment f patients with cardiac arrest due to accidental hypothermia.1 The uthors screened 3800 cardiac arrest patients treated from 1991 to 010. Overall, 18 patients were identified with presumed hypotheric cardiac arrest (core temperature of <28 ◦C) and a return of pontaneous circulation. Of these, 50% (n = 9) survived to hospial discharge and all of those (100%, n = 9) survived with good eurologic outcome. Although the patient sample size is small, he outcome is markedly better compared with studies involvng normothermic cardiac arrest patients and similar to previously ublished accidental hypothermia case series.2 Patients who cool to a low core temperature before developng cardiac arrest are somewhat protected from ischaemia given hat cerebral oxygen consumption decreases by ∼6% per 1 ◦C f cooling.3 In normothermic cardiac arrest without cardiopulonary resuscitation (CPR), ischaemia >∼3–5 min is associated ith considerable neurologic injury. With deep hypothermic cirulatory arrest (DHCA), usually 18–20 ◦C, ≤30 min of cardiac arrest s commonly used to facilitate aortic surgery without neurologic ysfunction. In the absence of CPR almost all patients will sufer neurologic dysfunction with >60 min of cardiac arrest, even n the presence of deep hypothermia. Traditional CPR may proide ≤40% of normal cerebral blood flow and is therefore used uring cardiac arrest to provide oxygen delivery during resusciation attempts.4 In hypothermic cardiac arrest, patients are able o tolerate prolonged periods of CPR (≥5 h) with good neurologic utcome.5 In accidental hypothermia case series; patients typically have a ood neurological outcome or do not survive to hospital discharge. xplanations for the good outcomes may include deep hypotheric conservation during relatively short (<60 min) non-asphyctic ardiac arrest, or an undetectable low flow state prior to emerency medical services (EMS) assessment complicated by rescue ollapse (i.e. cardiac arrest) at first contact. The hypothermic yocardium is extremely irritable and the simple process of ositioning and transporting a patient may be enough to trigger systole or ventricular fibrillation.6 The non-survivors are likely mix of normothermic cardiac arrest with subsequent cooling,