Successful Defibrillation at a Core Temperature of 18.2 Degrees Celsius

Environmental Hypothermia

Although a rare diagnosis in the Emergency Department, hypothermia affects patients in all environments, from urban to mountainous settings. Classic signs of death cannot be interpreted in the hypothermic patient, thus resulting in the mantra, "No one is dead until they're warm and dead." This comprehensive review of environmental hypothermia covers the clinical significance and pathophysiology of hypothermia, pearls and pitfalls in the prehospital management of hypothermia (including temperature measurement techniques and advanced cardiac life support deviations), necessary Emergency Department diagnostics, available rewarming modalities including extracorporeal life support, and criteria for termination of resuscitation.

Associations between prehospital defibrillation and outcomes of out-of-hospital cardiac arrests presumed to be caused by hypothermia: A nationwide observational study with epidemiological analysis

This study aimed to clarify the epidemiology of out of-hospital cardiac arrest (OHCA) cases caused by hypothermia. The associations between the presence/absence of shockable initial electrocardiography rhythm, prehospital defibrillation and the outcomes of OHCA were also investigated. This study involved the retrospective analysis of prospectively collected, nationwide, population-based data for OHCA cases caused by hypothermia. One thousand five hundred seventy-five emergency medical service (EMS)-confirmed OHCA cases with hypothermia, recorded between 2013 and 2019, were extracted from the Japanese nationwide database. The primary outcome was neurologically favorable 1-month survival, defined as cerebral performance category 1 or 2. The secondary outcome was 1-month survival. OHCA cases with hypothermia occurred more frequently in the winter. In approximately half (837) of the hypothermic OHCA cases, EMS was activated in the morning (6:00 am to 11:59 am). Shockable initial electrocardiogram rhythms were recorded in 30.8% (483/1570) of cases. prehospital defibrillation was attempted in 96.1% (464/483) of cases with shockable rhythms and 25.8% (280/1087) of cases with non-shockable initial rhythms. EMS-witnessed cases, prolonged transportation time intervals and prehospital epinephrine administration were associated with rhythm conversion in cases with non-shockable initial rhythms. Binominal logit test followed by multivariable logistic regression revealed that shockable initial rhythms were associated with better outcomes. prehospital defibrillation was not significantly associated with better outcomes, regardless of the type of initial rhythm (shockable or non-shockable). Transportation to high-level emergency hospitals was associated with better outcomes (adjusted odds ratio: 2.94, 95% confidence interval: 1.66-5.21). In hypothermic OHCA, shockable initial rhythm but not prehospital defibrillation is likely to be associated with better neurologically favorable outcomes. In addition, transport to a high-level acute care hospital may be appropriately considered despite prolonged transport. Further investigation, including core temperature data in analyses, is necessary to determine the benefit of prehospital defibrillation in hypothermic OHCA.

Successful Pre-Rewarming Resuscitation after Cardiac Arrest in Severe Hypothermia: A Retrospective Cohort Study from the International Hypothermia Registry

The aim of our study is to investigate successful pre-rewarming resuscitation after hypothermic cardiac arrest (HCA). The hypothermic heart may be insensitive to defibrillation when core temperature is below 30 °C and after successful defibrillation, sinus rhythm often returns into ventricular fibrillation. Recurrent defibrillation attempts may induce myocardial injury. Discrepancy exists concerning pre-rewarming defibrillation between the guidelines of the European Resuscitation Council and American Heart Association. The International Hypothermia Registry (IHR) gathers hypothermia cases. The primary outcome was survival. Secondary outcomes were the characteristics of defibrillation, the effect of Adrenaline administration under 30 °C, and the duration of CPR. Of the 239 patients, eighty-eight were in cardiac arrest at arrival of the rescue team. Successful pre-rewarming resuscitation was obtained in 14 patients. The outcome showed: seven deaths, one vegetative state, two patients with reversible damage, and four patients with full recovery. A total of five patients had a shockable rhythm, and defibrillation was successful in four patients. The response rate to Adrenaline was reported as normal in six patients. There were no statistically significant differences in the presence of a shockable rhythm, the success of defibrillation, and the effect on Adrenaline administration between the survivors and non-survivors. Successful resuscitation in severe hypothermia is possible before active rewarming and arrival in the hospital, thus improving the chance of survival.

Rewarming From Hypothermic Cardiac Arrest Applying Extracorporeal Life Support: A Systematic Review and Meta-Analysis

Introduction: This systematic review and meta-analysis aims at comparing outcomes of rewarming after accidental hypothermic cardiac arrest (HCA) with cardiopulmonary bypass (CPB) or/and extracorporeal membrane oxygenation (ECMO). Material and Methods: Literature searches were limited to references with an abstract in English, French or German. Additionally, we searched reference lists of included papers. Primary outcome was survival to hospital discharge. We assessed neurological outcome, differences in relative risks (RR) of surviving, as related to the applied rewarming technique, sex, asphyxia, and witnessed or unwitnessed HCA. We calculated hypothermia outcome prediction probability score after extracorporeal life support (HOPE) in patients in whom we found individual data. P < 0.05 considered significant. Results: Twenty-three case observation studies comprising 464 patients were included in a meta-analysis comparing outcomes of rewarming with CPB or/and ECMO. One-hundred-and-seventy-two patients (37%) survived to hospital discharge, 76 of 245 (31%) after CPB and 96 of 219 (44 %) after ECMO; 87 and 75%, respectively, had good neurological outcomes. Overall chance of surviving was 41% higher (P = 0.005) with ECMO as compared with CPB. A man and a woman had 46% (P = 0.043) and 31% (P = 0.115) higher chance, respectively, of surviving with ECMO as compared with CPB. Avalanche victims had the lowest chance of surviving, followed by drowning and people losing consciousness in cold environments. Assessed by logistic regression, asphyxia, unwitnessed HCA, male sex, high initial body temperature, low pH and high serum potassium (s-K+) levels were associated with reduced chance of surviving. In patients displaying individual data, overall mean predictive surviving probability (HOPE score; n = 134) was 33.9 ± 33.6% with no significant difference between ECMO and CPB-treated patients. We also surveyed 80 case reports with 96 victims of HCA, who underwent resuscitation with CPB or ECMO, without including them in the meta-analysis. Conclusions: The chance of surviving was significantly higher after rewarming with ECMO, as compared to CPB, and in patients with witnessed compared to unwitnessed HCA. Avalanche victims had the lowest probability of surviving. Male sex, high initial body temperature, low pH, and high s-K+ were factors associated with low surviving chances.