title: The capability of professional- and lay-rescuers to estimate the chest compression-depth target: a short, randomized experiment.
abstract: BACKGROUND
  In CPR, sufficient compression depth is essential. The American Heart Association ("at least 5cm", AHA-R) and the European Resuscitation Council ("at least 5cm, but not to exceed 6cm", ERC-R) recommendations differ, and both are hardly achieved. This study aims to investigate the effects of differing target depth instructions on compression depth performances of professional and lay-rescuers.
  
  
  METHODS
  110 professional-rescuers and 110 lay-rescuers were randomized (1:1, 4 groups) to estimate the AHA-R or ERC-R on a paper sheet (given horizontal axis) using a pencil and to perform chest compressions according to AHA-R or ERC-R on a manikin. Distance estimation and compression depth were the outcome variables.
  
  
  RESULTS
  Professional-rescuers estimated the distance according to AHA-R in 19/55 (34.5%) and to ERC-R in 20/55 (36.4%) cases (p=0.84). Professional-rescuers achieved correct compression depth according to AHA-R in 39/55 (70.9%) and to ERC-R in 36/55 (65.4%) cases (p=0.97). Lay-rescuers estimated the distance correctly according to AHA-R in 18/55 (32.7%) and to ERC-R in 20/55 (36.4%) cases (p=0.59). Lay-rescuers yielded correct compression depth according to AHA-R in 39/55 (70.9%) and to ERC-R in 26/55 (47.3%) cases (p=0.02).
  
  
  CONCLUSIONS
  Professional and lay-rescuers have severe difficulties in correctly estimating distance on a sheet of paper. Professional-rescuers are able to yield AHA-R and ERC-R targets likewise. In lay-rescuers AHA-R was associated with significantly higher success rates. The inability to estimate distance could explain the failure to appropriately perform chest compressions. For teaching lay-rescuers, the AHA-R with no upper limit of compression depth might be preferable.
authors: Municipal Ambulance Service Vienna, MA 70, Berufsrettung der Stadt Wien, Austria; Department of Emergency Medicine, Medical University of Vienna, Austria.
authors: Raphael
authors: R
authors: van Tulder
authors: Department of Emergency Medicine, Medical University of Vienna, Austria.
authors: Roberta
authors: R
authors: Laggner
authors: Department of Emergency Medicine, Medical University of Vienna, Austria.
authors: Calvin
authors: C
authors: Kienbacher
authors: University Hospital Tulln, Hospital Association Lower Austria, Austria.
authors: Bernhard
authors: B
authors: Schmid
authors: Municipal Ambulance Service Vienna, MA 70, Berufsrettung der Stadt Wien, Austria.
authors: Andreas
authors: A
authors: Zajicek
authors: Municipal Ambulance Service Vienna, MA 70, Berufsrettung der Stadt Wien, Austria.
authors: Jochen
authors: J
authors: Haidvogel
authors: Municipal Ambulance Service Vienna, MA 70, Berufsrettung der Stadt Wien, Austria.
authors: Dieter
authors: D
authors: Sebald
authors: Department of Emergency Medicine, Medical University of Vienna, Austria.
authors: Anton N
authors: AN
authors: Laggner
authors: Department of Emergency Medicine, Medical University of Vienna, Austria. Electronic address: harald.herkner@meduniwien.ac.at.
authors: Harald
authors: H
authors: Herkner
authors: Department of Emergency Medicine, Medical University of Vienna, Austria.
authors: Fritz
authors: F
authors: Sterz
authors: Department of Emergency Medicine, Medical University of Vienna, Austria; Department of Emergency Medicine, Wilheminenspital, Vienna Hospital Association, Vienna, Austria.
authors: Philip
authors: P
authors: Eisenburger
mesh_terms: D000328:Adult; D016887:Cardiopulmonary Resuscitation / Q000193:education*; D002983:Clinical Competence; D060731:Emergency Responders; D005260:Female; D006323:Heart Arrest / Q000628:therapy*; D006336:Heart Massage; D006801:Humans; D008297:Male; D008348:Manikins; D008875:Middle Aged; D011787:Quality of Health Care; D015203:Reproducibility of Results; D055815:Young Adult
keywords: Cardiac arrest; Cardiopulmonary resuscitation; Chest compression; Manikin