title: Is CPR quality improving? A retrospective study of out-of-hospital cardiac arrest.
abstract: OBJECTIVE
  To evaluate the quality of cardiopulmonary resuscitation (CPR) performed by a physician-manned ambulance, and assess whether it changed with time influenced by developing scientific evidence and guideline changes.
  
  
  METHODS
  A retrospective, observational study of all cardiac arrest patients (except trauma) older than 18 years treated between May 2003 and December 2006 by the physician-manned ambulance in Oslo. CPR quality was assessed from continuous electronic recordings from the defibrillators (LIFEPAK 12, Physio-Control or a modified Heartstart 4000, Philips Medical Systems). Ventilations were assessed from changes in transthoracic impedance, chest compressions from transthoracic impedance for LIFEPAK 12 and from an accelerometer for Heartstart 4000 (nine patients). Values are given as mean+/-S.D. and differences analysed with ANOVA and unpaired Student's t-test with Bonferroni correction.
  
  
  RESULTS
  Forty-eight of 169 consecutive cases were excluded from CPR quality analysis, 47 due to missing defibrillator data and one due to a short arrest time (<1min). Hands-off intervals (fraction of time without spontaneous circulation where no chest compressions are given) were reduced from 0.18+/-0.11 in 2003 to 0.10+/-0.06 in 2006 (p=0.03). Compression and ventilation rates were significantly reduced from 122+/-12 and 16+/-3min(-1), respectively in 2003 to 111+/-10 and 12+/-3 in 2006 (p<0.0001 and p=0.001). In 2003-2004 10% were discharged alive versus 16% in 2005-2006 (p=0.3, Chi-square test).
  
  
  CONCLUSIONS
  High quality CPR is achievable out-of-hospital, and the improvement with time could reflect developing scientific evidence focusing on reducing hands-off intervals and hyperventilation.
authors.affiliation: Institute for Experimental Medical Research, Ulleval University Hospital, University of Oslo, N-0407 Oslo, Norway. t.m.olasveengen@medisin.uio.no
authors.forename: Theresa M
authors.initials: TM
authors.lastname: Olasveengen
authors.forename: Lars
authors.initials: L
authors.lastname: Wik
authors.forename: Jo
authors.initials: J
authors.lastname: Kramer-Johansen
authors.forename: Kjetil
authors.initials: K
authors.lastname: Sunde
authors.forename: Morten
authors.initials: M
authors.lastname: Pytte
authors.forename: Petter A
authors.initials: PA
authors.lastname: Steen
mesh_terms: D000368:Aged; D016887:Cardiopulmonary Resuscitation / Q000592:standards* / Q000639:trends; D004632:Emergency Medical Services / Q000592:standards* / Q000639:trends; D005260:Female; D005500:Follow-Up Studies; D006323:Heart Arrest / Q000401:mortality / Q000628:therapy*; D006801:Humans; D008297:Male; D009664:Norway / Q000453:epidemiology; D011785:Quality Assurance, Health Care / Q000379:methods*; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends