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Efficacy of metronome sound guidance via a phone speaker during dispatcher-assisted compression-only cardiopulmonary resuscitation by an untrained layperson: a randomised controlled simulation study using a manikin
  1. Sang O Park1,
  2. Chong Kun Hong2,
  3. Dong Hyuk Shin3,
  4. Jun Ho Lee2,
  5. Seong Youn Hwang2
  1. 1Department of Emergency Medicine, Konkuk University School of Medicine, Konkuk University, Konkuk University Medical Center, Seoul, Republic of Korea
  2. 2Department of Emergency Medicine, Sungkyunkwan University School of Medicine, Samsung Changwon Hospital, Changwon, Republic of Korea
  3. 3Department of Emergency Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
  1. Correspondence to Professor Seong Youn Hwang, Department of Emergency Medicine, Sungkyunkwan University School of Medicine, Samsung Changwon Hospital, Changwon, Republic of Korea; 630-723. schsfc{at}


Aim Untrained laypersons should perform compression-only cardiopulmonary resuscitation (COCPR) under a dispatcher's guidance, but the quality of the chest compressions may be suboptimal. We hypothesised that providing metronome sounds via a phone speaker may improve the quality of chest compressions during dispatcher-assisted COCPR (DA-COCPR).

Methods Untrained laypersons were allocated to either the metronome sound-guided group (MG), who performed DA-COCPR with metronome sounds (110 ticks/min), or the control group (CG), who performed conventional DA-COCPR. The participants of each group performed DA-COCPR for 4 min using a manikin with Skill-Reporter, and the data regarding chest compression quality were collected.

Results The data from 33 cases of DA-COCPR in the MG and 34 cases in the CG were compared. The MG showed a faster compression rate than the CG (111.9 vs 96.7/min; p=0.018). A significantly higher proportion of subjects in the MG performed the DA-COCPR with an accurate chest compression rate (100–120/min) compared with the subjects in the CG (32/33 (97.0%) vs 5/34 (14.7%); p<0.0001). The mean compression depth was not different between the MG and the CG (45.9 vs 46.8 mm; p=0.692). However, a higher proportion of subjects in the MG performed shallow compressions (compression depth <38 mm) compared with subjects in the CG (median % was 69.2 vs 15.7; p=0.035).

Conclusions Metronome sound guidance during DA-COCPR for the untrained bystanders improved the chest compression rates, but was associated more with shallow compressions than the conventional DA-COCPR in a manikin model.

  • resuscitation
  • prehospital care, despatch
  • prehospital care, first responders
  • first responders

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