Effects of a voice metronome on compression rate and depth in telephone assisted, bystander cardiopulmonary resuscitation: an investigator-blinded, 3-armed, randomized, simulation trial
van Tulder R, Roth D, Krammel M, Laggner R, Schriefl S, Kienbacher C, Hartmann AL, Novosad H, Chwojka CC, Havel C, Schreiber W, Herkner H
Affiliation of the authors
Department of Emergency Medicine, Medical University of Vienna, Austria. Department of General Anaesthesiology, Intensive Care and Pain Management, Viena, Austria. NOTRUF NOE GmbH, Emergency Call and Coordination Centre, Lower Austria, Viena, Austria.
van Tulder R, Roth D, Krammel M, Laggner R, Schriefl S, Kienbacher C, et al. Effects of a voice metronome on compression rate and depth in telephone assisted, bystander cardiopulmonary resuscitation: an investigator-blinded, 3-armed, randomized, simulation trial. Emergencias. 2015;27:357-63
Summary
Objective.
We investigated the effect on compression rate and depth of a conventional metronome and a voice metronome in simulated telephone-assisted, protocol-driven bystander Cardiopulmonary resucitation (CPR) compared to standard instruction.
Methods.
Thirty-six lay volunteers performed 10 minutes of compression-only CPR in a prospective, investigator-blinded, 3-arm study on a manikin. Participants were randomized either to standard instruction (“push down firmly, 5 cm”), a regular metronome pacing 110 beats per minute (bpm), or a voice metronome continuously prompting “deep-deepdeep-
deeper” at 110 bpm. The primary outcome was deviation from the ideal chest compression target range (50 mm compression depth x 100 compressions per minute x 10 minutes = 50 m). Secondary outcomes were CPR quality measures (compression and leaning depth, rate, no-flow times) and participants’ related physiological response (heart rate,
blood pressure and nine hole peg test and borg scales score). We used a linear regression model to calculate effects.
Results.
The mean (SD) deviation from the ideal target range (50 m) was –11 (9) m in the standard group, –20 (11) m in the conventional metronome group (adjusted difference [95%, CI], 9.0 [1.2-17.5 m], P=.03), and –18 (9) m in the voice metronome group (adjusted difference, 7.2 [–0.9–15.3] m, P=.08). Secondary outcomes (CPR quality measures and physiological response of participants to CPR performance) showed no significant differences.
Conclusion. Compared to standard instruction, the conventional metronome showed a significant negative effect on the chest compression target range. The voice metronome showed a non-significant negative effect and therefore cannot be recommended for regular use in telephone-assisted CPR.
