title: 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.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Emergency Medicine, Konkuk University School of Medicine, Konkuk University, Konkuk University Medical Center, Seoul, Republic of Korea.
authors.forename: Sang O
authors.initials: SO
authors.lastname: Park
authors.forename: Chong Kun
authors.initials: CK
authors.lastname: Hong
authors.forename: Dong Hyuk
authors.initials: DH
authors.lastname: Shin
authors.forename: Jun Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Seong Youn
authors.initials: SY
authors.lastname: Hwang
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D019454:Chronotherapy / Q000379:methods*; D005260:Female; D006323:Heart Arrest / Q000628:therapy*; D006801:Humans; D008297:Male; D008348:Manikins; D008875:Middle Aged; D009991:Oscillometry / Q000379:methods; D016544:Patient Simulation; D013016:Sound; D055815:Young Adult