title: A higher chest compression rate may be necessary for metronome-guided cardiopulmonary resuscitation.
abstract: OBJECTIVE
  Metronome guidance is a simple and economical feedback system for guiding cardiopulmonary resuscitation (CPR). However, a recent study showed that metronome guidance reduced the depth of chest compression. The results of previous studies suggest that a higher chest compression rate is associated with a better CPR outcome as compared with a lower chest compression rate, irrespective of metronome use. Based on this finding, we hypothesized that a lower chest compression rate promotes a reduction in chest compression depth in the recent study rather than metronome use itself.
  
  
  METHODS
  One minute of chest compression-only CPR was performed following the metronome sound played at 1 of 4 different rates: 80, 100, 120, and 140 ticks/min. Average compression depths (ACDs) and duty cycles were compared using repeated measures analysis of variance, and the values in the absence and presence of metronome guidance were compared.
  
  
  RESULTS
  Both the ACD and duty cycle increased when the metronome rate increased (P = .017, <.001). Average compression depths for the CPR procedures following the metronome rates of 80 and 100 ticks/min were significantly lower than those for the procedures without metronome guidance.
  
  
  CONCLUSIONS
  The ACD and duty cyle for chest compression increase as the metronome rate increases during metronome-guided CPR. A higher rate of chest compression is necessary for metronome-guided CPR to prevent suboptimal quality of chest compression.
authors.affiliation: Department of Emergency Medicine, Yonsei University College of Medicine, Seodaemun-Gu, Seoul 120-752, Republic of Korea. hendrix74@gmail.com
authors.forename: Tae Nyoung
authors.initials: TN
authors.lastname: Chung
authors.forename: Sun Wook
authors.initials: SW
authors.lastname: Kim
authors.forename: Je Sung
authors.initials: JS
authors.lastname: You
authors.forename: Young Soon
authors.initials: YS
authors.lastname: Cho
authors.forename: Sung Phil
authors.initials: SP
authors.lastname: Chung
authors.forename: Incheol
authors.initials: I
authors.lastname: Park
mesh_terms: D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D018592:Cross-Over Studies; D006336:Heart Massage / Q000379:methods*; D006801:Humans; D016544:Patient Simulation; D013997:Time Factors