title: Effects of compression-to-ventilation ratio on compression force and rescuer fatigue during cardiopulmonary resuscitation.
abstract: BACKGROUND
  Although increasing consecutive compressions during cardiopulmonary resuscitation (CPR) is beneficial to patients, it possibly affects the workload and, ultimately, the quality of CPR. This study examines the effects of compression-to-ventilation ratio on external chest compression performance of rescuers.
  
  
  METHODS
  Subjects were 17 health care providers. Each participant performed CPR with 3 compression-to-ventilation ratios: 15:2, 30:2, and 50:5. The duration of CPR was 5 minutes in each group, with a rest period of 50 minutes in between. The manikin was equipped with a 6-axis force load cell to measure the force applied. An 8-camera digital motion analysis system was used to collect the 3-dimensional trajectory information. Data were compared using the crossover design. Ratings of perceived exertion and body area discomfort were measured.
  
  
  RESULTS
  The mean compression forces (in Newtons) delivered at 1 minute 20 seconds to 1 minute 40 seconds and at 4 minutes 20 seconds to 4 minutes 40 seconds were 494.65 ± 53.58 and 478.64 ± 50.29, respectively (P = .047), for compression-to-ventilation ratios of 15:2; 473.57 ± 49.69 and 435.59 ± 56.79, respectively (P < .001), for ratios of 30:2; and 468.44 ± 38.05 and 442.18 ± 43.40, respectively (P = .012), for ratio of 50:5. Diminished compression force in the ratio 50:5 was observed at 1 minute 20 seconds, and in the 30:2 ratio, it was observed at 4 minutes 20 seconds. The mean joint angles in each group did not differ significantly between 1 minute 20 seconds and 4 minutes 20 seconds. The Ratings of Perceived Exertion Scale was 3.38 ± 1.64 in 15:2, 4.06 ± 1.43 in 30:2, and 4.35 ± 1.54 in 50:5 (P = .045). Waist discomfort was noted in 50:5 after 4 minutes 20 seconds of external chest compression.
  
  
  CONCLUSIONS
  Rescuer fatigue must be considered when raising the consecutive compression during CPR. Switching the compressor every 2 minutes should be followed where possible.
authors.affiliation: Department of Emergency Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chih-Hsien
authors.initials: CH
authors.lastname: Chi
authors.forename: Jui-Yi
authors.initials: JY
authors.lastname: Tsou
authors.forename: Fong-Chin
authors.initials: FC
authors.lastname: Su
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D016887:Cardiopulmonary Resuscitation / Q000523:psychology / Q000706:statistics & numerical data*; D005221:Fatigue; D005260:Female; D006336:Heart Massage / Q000523:psychology / Q000706:statistics & numerical data*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D005082:Physical Exertion; D013997:Time Factors; D013996:Time and Motion Studies