Influence of a 100-M Simulated In-Water Rescue on Cardiopulmonary Parameters

Abstract

Objective: Cardiopulmonary resuscitation (CPR) after a drowning episode is performed under fatigue conditions. However, the characterization of CPR in this context is still unknown. Our purpose was to investigate the effect of a 100-m simulated in-water rescue on CPR and physiological parameters in trained certified lifeguards.

Methods: Thirty trained certified lifeguards (age 24.6 ± 3.8 yrs; height 178.2 ± 7.4 cm and weight 76.9 ± 10.6 kg) completed two protocols using an adult manikin: (i) 4-min CPR after 4-min baseline conditions (CPR), and (ii) 4-min CPR after a 100-m simulated in-water rescue in the sea (CPR Rescue), both with a compression-ventilation ratio of 30:2. Physiological parameters of the subjects were continuously measured (breath-by-breath) during baseline and CPR conditions, using a telemetric portable gas analyzer (K4b ² , Cosmed, Rome, Italy) and CPR techniques analyzed using two HD video cameras (Sony, HDR PJ30VE, Japan).

Results: The 100-m simulated in-water rescue induced higher values of physiological related parameters all over the 4-min CPR exercise (e.g. Tidal Volume: 1.5 ± 0.4 and 2.4 ± 0.5 L; VO₂: 15.9 ± 3.9 and 22.8 ± 3.2 ml.kg^-1.min^-1; R: 0.9 ± 0.1 and 1.2 ± 0.1, for CPR and CPR Rescue, respectively). However, the compression rate was higher in CPR Rescue compared to the CPR in the first (cycle 3: 85 ± 12 vs. 78 ± 9 s) and last three complete cycles (cycle 12: 100 ± 12 and 85 ± 12 s), and, in both conditions, it increased from the first to the last CPR complete cycle.

Conclusions: Fatigue induced by the 100-m simulated in-water rescue had a strong physiological expression but a minimal impact on CPR performance. Key words: CPR; fatigue; lifeguards; VO₂.