Effects of altitude on biceps brachii and erector spinae muscles oxygen saturation during basic cardiopulmonary resuscitation: a simulation study

Objective: To assess biceps brachii and erector spinae muscular oxygen saturation (SmO2) by near infrared spectroscopy (NIRS), during 10 minutes of resuscitation at simulated altitudes of 600, 3000 and 5000 m before and after carrying out a simulation program for adaptation to hypoxia. Performing and maintaining a good-quality cardiopulmonary resuscitation (CPR) at higher altitudes may pose a significant challenge to resuscitators due to decrease in arterial oxygen saturation. This fact adversely effects the quality of resuscitation. Methods: Participants performed 10 minutes of CPR on a mannequin in the laboratory in environments that simulated altitudes. Subsequently, a standardized altitude conditioning protocol was carried out using intermittent hypoxia. The participants performed CPR again under the conditions and altitudes previously referred to. Results: Initial heart rate (HR) at 5000 > 3000 m, and both > 600 m. HR at each altitude was higher conditioning at the end of CPR. The SmO2 of both muscles showed no differences at the beginning and at the end of CPR and was higher in both muscles after the conditioning program before and at the end of CPR. In both muscles, SmO2 values before and after conditioning show a slightly increasing trend during CPR. Conclusion: NIRS use allows developing an optimum training plan. The rescuer will know his limits and optimize his performance. The improvement in physical performance and recovery capacity induced by intermittent hypoxia conditioning programs increases the quality of CPR in prolonged cardiac arrests and in adverse conditions, such as at high altitudes.