Background: Out-of-hospital cardiac arrest (OHCA) in children is rare and can potentially result in severe neurological impairment. Our study aimed to identify characteristics of and factors associated with favourable neurological outcome following the resuscitation of children by the Swiss helicopter emergency medical service. Materials and methods: This retrospective observational study screened the Swiss Air-Ambulance electronic database from 01-01-2011 to 31-12-2021. We included all primary missions for patients ≤ 16 years with OHCA. The primary outcome was favourable neurological outcome after 30 days (cerebral performance categories (CPC) 1 and 2). Multivariable linear regression identified potential factors associated with favourable outcome (odd ratio – OR). Results: Having screened 110,331 missions, we identified 296 children with OHCA, which we included in the analysis. Patients were 5.0 [1.0; 12.0] years old and 61.5% (n = 182) male. More than two-thirds had a non-traumatic OHCA (67.2%, n = 199), while 32.8% (n = 97) had a traumatic OHCA. Thirty days after the event, 24.0% (n = 71) of patients were alive, 18.9% (n = 56) with a favourable neurological outcome (CPC 1 n = 46, CPC 2 n = 10). Bystander cardiopulmonary resuscitation (OR 10.34; 95%CI 2.29–51.42; p = 0.002) and non-traumatic aetiology (OR 11.07 2.38–51.42; p = 0.002) were the factors most strongly associated with favourable outcome. Factors associated with an unfavourable neurological outcome were initial asystole (OR 0.12; 95%CI 0.04–0.39; p < 0.001), administration of adrenaline (OR 0.14; 95%CI 0.05–0.39; p < 0.001) and ongoing chest compression at HEMS arrival (OR 0.17; 95%CI 0.04–0.65; p = 0.010). Conclusion: In this study, 18.9% of paediatric OHCA patients survived with a favourable neurologic outcome 30 days after treatment by the Swiss helicopter emergency medical service. Immediate bystander cardiopulmonary resuscitation and non-traumatic OHCA aetiology were the factors most strongly associated with a favourable neurological outcome. These results underline the importance of effective bystander and first-responder rescue as the foundation for subsequent professional treatment of children in cardiac arrest.

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.

Defibrillation often fails in patients in hypothermic cardiac arrest with shockable rhythms. In patients with core temperatures (Tc) ≤30°C the success rate, optimal number, timing of defibrillations, and factors including rewarming associated with successful defibrillation are not well known. To determine the success rate of defibrillation in patients in hypothermic cardiac arrest with shockable rhythms. We studied Tc at defibrillation attempt, number of shocks, and factors facilitating defibrillation. This was a retrospective observational study from the International Hypothermia Registry of patients with hypothermic cardiac arrest (Tc ≤30°C) and shockable rhythms undergoing defibrillation attempts before and during rewarming with or without extracorporeal life support. We performed multivariate binomial logistic regression to analyse the probability of defibrillation success according to the defibrillation temperature and ECLS rewarming. Thirty-seven patients with cardiac arrest, shockable rhythm, and Tc ≤30°C were included. Defibrillation was attempted in 20 patients before rewarming and in 17 during rewarming. The overall success rate was 22/37 (59%). Both the success rate of defibrillation (100% [17/17] vs. 25% [5/20]; P<0.001) and Tc at the time of the defibrillation attempt (29.0°C [28.0-30.0°C] vs 25.8°C [24.0-26.2°C]; P<0.001) were higher if defibrillation was performed during rewarming. No defibrillation attempt was successful at Tc <24.8°C. Defibrillation attempts can be successful before rewarming at Tc ≤30°C. The success rate is higher during rewarming and at a higher Tc. Tc is a strong and independent predictor of defibrillation success. Defibrillation at Tc <25°C is unlikely. These findings require confirmation in larger studies.