title: Effect of mattress and bed frame deflection on real chest compression depth measured with two CPR sensors.
abstract: OBJECTIVE
  Implementation of chest compression (CC) feedback devices with a single force and deflection sensor (FDS) may improve the quality of CPR. However, CC depth may be overestimated if the patient is on a compliant surface. We have measured the true CC depth during in-hospital CPR using two FDSs on different bed and mattress types.
  
  
  METHODS
  This prospective observational study was conducted at Tampere University Hospital between August 2011 and September 2012. During in-hospital CPR one FDS was placed between the rescuer's hand and the patient's chest, with the second attached to the backboard between the patient's back and the mattress. The real CC depth was calculated as the difference between the total depth from upper FDS to lower FDS.
  
  
  RESULTS
  Ten cardiac arrests on three different bed and mattress types yielded 10,868 CCs for data analyses. The mean (SD) mattress/bed frame effect was 12.8 (4) mm on a standard hospital bed with a gel mattress, 12.4 (4) mm on an emergency room stretcher with a thin gel mattress and 14.1 (3) mm on an ICU bed with an emptied air mattress. The proportion of CCs with an adequate depth (≥50 mm) decreased on all mattress types after compensating for the mattress/bed frame effect from 94 to 64%, 98 to 76% and 91 to 17%, in standard hospital bed, emergency room stretcher and ICU bed, respectively (p<0.001).
  
  
  CONCLUSIONS
  The use of FDS without real-time correction for deflection may result in CC depth not reaching the recommended depth of 50 mm.
authors.affiliation: Critical Care Medicine Research Group, Department of Intensive Care Medicine, Tampere University Hospital and University of Tampere, PO Box 2000, FI-33521 Tampere, Finland; Emergency Medical Services, Department of Emergency Medicine, Turku University Hospital, PO Box 52, FI-20521 Turku, Finland. Electronic address: marko.sainio@fimnet.fi.
authors.forename: Marko
authors.initials: M
authors.lastname: Sainio
authors.affiliation: Critical Care Medicine Research Group, Department of Intensive Care Medicine, Tampere University Hospital and University of Tampere, PO Box 2000, FI-33521 Tampere, Finland; School of Medicine, University of Tampere, FI-33014 University of Tampere, Finland.
authors.forename: Heidi
authors.initials: H
authors.lastname: Hellevuo
authors.affiliation: School of Health Sciences, University of Tampere, FI-33014 University of Tampere, Finland.
authors.forename: Heini
authors.initials: H
authors.lastname: Huhtala
authors.affiliation: Critical Care Medicine Research Group, Department of Intensive Care Medicine, Tampere University Hospital and University of Tampere, PO Box 2000, FI-33521 Tampere, Finland; Emergency Medical Services, Department of Emergency Medicine, Tampere University Hospital, PO Box 2000, FI-33521 Tampere, Finland.
authors.forename: Sanna
authors.initials: S
authors.lastname: Hoppu
authors.affiliation: Laerdal Medical AS, PO Box 377, N-4002 Stavanger, Norway.
authors.forename: Joar
authors.initials: J
authors.lastname: Eilevstjønn
authors.affiliation: Critical Care Medicine Research Group, Department of Intensive Care Medicine, Tampere University Hospital and University of Tampere, PO Box 2000, FI-33521 Tampere, Finland; Department of Surgical Sciences, Anaesthesiology and Intensive Care, Uppsala University, SE-751 85 Uppsala, Sweden.
authors.forename: Jyrki
authors.initials: J
authors.lastname: Tenhunen
authors.affiliation: Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, Helsinki University Central Hospital and Institute of Clinical Medicine, University of Helsinki, PO Box 340, FI-00029 HUS Helsinki, Finland.
authors.forename: Klaus T
authors.initials: KT
authors.lastname: Olkkola
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001513:Beds; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011312:Pressure; D011446:Prospective Studies
keywords: Beds; Cardiopulmonary resuscitation; Feedback; Mattresses; Resuscitation; Sensor