Influence of high altitude after a prior ascent on physical exhaustion during cardiopulmonary resuscitation: a randomised crossover alpine field experiment.

Performing BLS CPR causes exhaustion both at base level and at a high altitude. A further increase during CPR might imply a physiological reserve for adapting to additional physical exertion at high altitude. Phases of ventilation are much needed recovery-periods, but heart rates remain very high. Subjective measures of exhaustion, such as the BORG-scale, might lead to rescuers' overestimation of their own performance.