title: Effects of AED device features on performance by untrained laypersons.
abstract: OBJECTIVE
  Our study evaluates the impact of features of automated external defibrillators (AEDs) on the performance and speed of untrained laypersons to deliver a shock and initiate CPR after a shock.
  
  
  METHODS
  This was a randomized trial of volunteer laypersons without AED or advanced medical training. Subjects were assigned to use one of six different models of AEDs on a manikin in simulated cardiac arrest. No instructions on AED operation were provided. Primary endpoints were shock delivery and elapsed time from start to shock. Secondary endpoints included time to power-on, initiation of CPR, adequacy of pad placement and subjects' ratings of ease of use (1=very easy, 5=very difficult).
  
  
  RESULTS
  Most subjects (109/120; 91%) were able to deliver a shock. Median time from start of scenario to shock delivery was 79 s (IQR: 67-99). Of the 11 participants who did not deliver shock, eight never powered on the device. Time to power-on was shorter in devices with open lid (median 12s, IQR 8-27 s) and pull handle (17s, IQR 9-20s) mechanisms than with a push button (37s, IQR 18-69 s; p=0.000). Pad position on the manikin was judged adequate for 86 (77%) of the 111 subjects who placed pads. Devices which gave more detailed voice instruction for pad placement had higher rates of adequate pad position [38/39 (97%) versus 50/73 (68%), p=0.001]. With AEDs that provided step-by-step CPR instruction, 49/58 (84%) subjects began CPR compared to 26/51 (51%) with AEDs that only prompted to start CPR (p=0.01). Participants rated all the models easy to use (overall mean 1.48; individual device means 1.28-1.71).
  
  
  CONCLUSIONS
  Most untrained laypersons were successful in delivering a shock. Device features had the most impact on these functions: ability and time to power-on device, adequacy of pad position and initiation of CPR.
authors.affiliation: Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA. mosessovn@upmc.edu
authors.forename: Vincent N
authors.initials: VN
authors.lastname: Mosesso
authors.forename: Alan H
authors.initials: AH
authors.lastname: Shapiro
authors.forename: Karen
authors.initials: K
authors.lastname: Stein
authors.forename: Kelly
authors.initials: K
authors.lastname: Burkett
authors.forename: Henry
authors.initials: H
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016887:Cardiopulmonary Resuscitation / Q000193:education* / Q000295:instrumentation; D002983:Clinical Competence; D047548:Defibrillators / Q000592:standards*; D004521:Educational Measurement / Q000706:statistics & numerical data*; D004554:Electric Countershock / Q000295:instrumentation*; D005260:Female; D005500:Follow-Up Studies; D006323:Heart Arrest / Q000628:therapy*; D006801:Humans; D008297:Male; D008348:Manikins; D008875:Middle Aged; D011187:Posture; D011446:Prospective Studies; D013997:Time Factors; D055815:Young Adult