Temporal trends in chest compression quality during a metronome-guided CPR simulation: a secondary analysis of the RITMICO study.

BACKGROUND

High-quality cardiopulmonary resuscitation (CPR) is essential for improving outcomes after out-of-hospital cardiac arrest. The RITMICO study evaluated a newly developed double-click metronome, providing separate auditory cues for the compression and release phases, compared with a standard metronome. This secondary analysis investigated temporal changes in chest compression (CC) quality during prolonged manikin-based CPR simulations and explored factors associated with these trajectories.

METHODS

477 volunteers (54% male; mean age 34 ± 12 years) were included in the analysis. Compression depth, compression rate, and chest compression release velocity (CCRV) were recorded using an automated external defibrillator with CC quality analysis technology. Simulations were divided into 21 consecutive 5-s intervals, and median values for each metric were analyzed using linear mixed-effects models with subject-specific random effects.

RESULTS

Compression depth and CCRV progressively declined over time, indicating early deterioration in CPR quality during prolonged compressions. Compared with the standard metronome, the double-click metronome produced consistently higher values for all CPR quality metrics throughout the simulation (all p < 0.05). It also delayed the decline of CCRV below the suggested threshold, indicating better preservation of chest recoil quality. Male participants maintained compression depth and CCRV longer than female participants.

CONCLUSIONS

CPR quality deteriorated early during prolonged simulated chest compressions, particularly with respect to chest recoil. The use of a double-click metronome was associated with better preservation of CPR quality over time and a later deterioration in CCRV. These findings support a potential role for the double-click metronome in maintaining CPR quality during prolonged resuscitation, although confirmation in real-world clinical settings is needed.