title: [The effect of different methods of counting of rescue crew on the quality of cardiopulmonary resuscitation].
abstract: OBJECTIVE
  To compare the effective power of external chest compression and degree of exhaustion of rescue crew using different methods of counting, in order to establish a more appropriate and standard method of counting.
  
  
  METHODS
  Forty-eight subjects who had received formal training in basic life support (BLS) and advanced life support (ALS) were recruited randomly from doctors and nurses working in the emergency departments. The methods of counting were randomly selected which was performed first, and then they performed continuous chest compressions for 3 minutes using two different methods of counting with 30 minutes apart on the manikin, which was used in the hospital for cardiopulmonary resuscitation (CPR) training. The total number of compressions was recorded, and the number of those which were considered satisfactory, the peak heart rate of the performer and the time to reach peak heart were all recorded. Feeling of fatigue and discomfort was evaluated by self-reported survey results with the use of a visual analogue scale (VAS).
  
  
  RESULTS
  The total number of compressions attempted, the effective power of external chest compression and the mean compression depth when rescuers counted form 1 to 10, which were repeated for 3 times, were greater than those when rescuers counted from 1 to 30 during 3 minutes of CPR [(202.40+/-6.52) times vs. (173.50+/-5.68) times, (67.48+/-2.00)% vs. (57.81+/-2.00)%, (4.45+/-0/.34) cm vs. (4.05+/0.21) cm, all P<0.01]. The VAS scores (22.15+/-3.09) was lower than that when rescuers counted them from 1 to 30 (31.10+/-4.09, P<0.01). The time to reach peak heart rate [(124.88+/-5.40) s] was longer than that when rescuers counted them from 1 to 30 [(106.15+/-6.80) s, P<0.01]. There was no difference in peak heart rate between two methods of counting.
  
  
  CONCLUSIONS
  The effective power of external chest compression is greater when rescuers counted from 1 to 10 with repetition for 3 times than that when rescuers counted continuously from 1 to 30 during CPR. The method of counting from 1 to 10 with repetition for 3 times can save physical energy of rescue crew, so it can improve the quality of CPR to some extent.
authors.affiliation: Emergency Department of West China Hospital, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhan
authors.forename: Qing
authors.initials: Q
authors.lastname: He
authors.forename: Ya-xiong
authors.initials: YX
authors.lastname: Zhou
mesh_terms: D000328:Adult; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D005221:Fatigue; D005260:Female; D006336:Heart Massage / Q000379:methods*; D006801:Humans; D008297:Male; D008348:Manikins; D011446:Prospective Studies; D011786:Quality Control; D055815:Young Adult