Survival of cardiac arrest patients on ski slopes: A 10-year analysis of the Northern French Alps Emergency Network.

AIM: Intense physical activity, cold and altitude make mountain sports a cause of increased risk of out-of-hospital cardiac arrest (OHCA). The difficulties of pre-hospital management related to this challenging environment could be mitigated by the presence of ski-patrollers in ski areas and use of helicopters for medical rescue. We assess whether this particular situation positively impacts the chain of survival compared to the general population. METHODS: Analysis of prospectively collected data from the cardiac arrest registry of the Northern French Alps Emergency Network (RENAU) from 2004 to 2014. RESULTS: 19,341 OHCAs were recorded during the period, including 136 on-slope events. Compared to other OHCAs, on-slope patients were younger (56 [40-65] vs. 66 [52-79] years, p<0.001) and more often in shockable initial rhythm (41.2% vs 20.1%, p<0.001). Resuscitation was more frequently started by a witness (43.4% vs 26.8%, p<0.001) and the time to the first electric shock was shorter (7.5min vs 14min, p<0.001), whereas time to the advanced life support (ALS) rescue arrival did not differ. The 30-day survival rate was higher for on-slope arrests (21.3% vs 5.9%, p<0.001, RR=3.61). In multivariate analysis, on-slope CA remained a positive 30-day survival factor with a 2.6 odds ratio (95% confidence interval, 1.42-4.81, p=0.002). CONCLUSION: Despite difficult access and management conditions, patients undergoing OHCAs on ski slopes presented a higher survival rate, possibly explained by a healthier population, the efficiency of resuscitation by ski-patrols and similar time to ALS facilities compared to other cardiac arrests.

The impact of hypothermia on serum potassium concentration: A systematic review.

BACKGROUND: Blood potassium is the main prognostic biomarker used for triage in hypothermic cardiac arrest. The aim of this review was to assess the impact of hypothermia on blood potassium levels and compare the underlying pathophysiological theories. METHODS: The Medline electronic database was searched via PubMed for articles published from January 1970 to December 2016. The search strategy included studies related to hypothermia and potassium levels. The relevant literature on clinical studies and experimental studies was reviewed by the authors. RESULTS: Among the 50 studies included in the review, 39 (78%) reported a decrease in blood potassium levels upon hypothermia onset. Hypothermic hypokalaemia is linked to an intracellular shift rather than an actual net loss. The intracellular shift is caused by a variety of factors such as enhanced functioning of Na+K+ATPase, beta-adrenergic stimulation, pH and membrane stabilisation in deep hypothermia. In contrast, hypothermia can act as an aggravating factor in severe trauma with hyperkalaemia being an indicator of an irreversible state of cell death. An increase in the blood potassium level during hypothermia may result from a lack of enzyme functioning at cold temperatures and blocked active transport. CONCLUSION: Hypothermia causes an initial decrease of potassium levels; however, the final stage of hypothermic cardiac arrest can induce hyperkalaemia due to cell lysis and final depolarisation. Better understanding the physiopathology of potassium levels during accidental hypothermia could be critically important to better select patients who could benefit from aggressive resuscitation therapy such as extracorporeal cardiopulmonary resuscitation.