Introduction. Previous studies have suggested that differences in rescuer strength and compression shift cycle are strongly associated with the quality of chest compression. We hypothesised that changing the shift cycle from two minutes to one would have a positive effect on the quality of chest compression in two-rescuer cardiopulmonary resuscitation (CPR), regardless of rescuer strength.

Methods.Thirty-nine senior medical students participated in this prospective, simulation-based, crossover study. After evaluation of muscle strength using a handgrip dynamometer, each participant was required to perform two sets of compressions separated by a 15-minute rest. Participants started with either four cycles of chest compressions for one minute followed by a one-minute rest (1-MCS), or with two cycles of chest compressions for two minutes followed by a two-minute rest (2-MCS). After a 15-minute break, participants switched groups and performed the other set of compressions. Mean compression depth (MCD), mean adequate compression (MAC), and adequate compression ratio (ACR) per minute were measured for each group. Subjective fatigue was reported after the completion of each set of compression cycles. Results. Rescuer strength was strongly correlated with MCD (p <0.01), MAC ratio (p <0.01), and ACR (p <0.01), and cycle group was correlated with MCD (p <0.01) and ACR (p =0.03). Subjective fatigue with 1-MCS was lower than with 2-MCS, regardless of rescuer strength.

Conclusion. We found that the quality of chest compressions could be improved by changing the shift cycle from two minutes to one, regardless of rescuer strength. Therefore, reducing the existing shift cycle recommended in guidelines for two rescuers could be beneficial.

Key words: CPR, fatigue, hand strength

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