Physiological Response of Quality Cardiopulmonary Resuscitation, Crossover Trial on Mannequin in Extreme Temperature Conditions.

Background: To determine the relationship between physiological fatigue and the quality of cardiopulmonary resuscitation (CPR) in trained resuscitators in hostile thermal environments (extreme cold and heat) simulating the different conditions found in an out-of-hospital cardiorespiratory arrest.

Methods: Prospective observational study involving 60 students of the health sciences with training in resuscitation, who simulated CPR on a mannequin for 10 min in different thermal environments: thermo-neutral environment (21 °C and 60% humidity), heat environment (41 °C and 98% humidity) and cold environment (-35 °C and 80% humidity). Physiological parameters (heart rate and lactic acid) and CPR quality were monitored.

Results: We detected a significant increase in the number of compressions per minute in the "heat environment" group after three minutes and in the mean rate after one minute. We observed a negative correlation between the total number of compressions and mean rate with respect to mean depth. The fraction of compressions (proportion of time in which chest compressions are carried out) was significant over time and the mean rate was higher in the "heat environment". Physiological parameters revealed no differences in heart rate depending on the resuscitation scenario; however, there was a greater and faster increase in lactate in the "heat environment" (significant at minute 3). The total proportion of participants reaching metabolic fatigue was also higher in the "heat environment".

Conclusions: A warm climate modifies metabolic parameters, reducing the quality of the CPR maneuver.