title: Rescuer's position and energy consumption, spinal kinetics, and effectiveness of simulated cardiac compression.
abstract: BACKGROUND
  Cardiopulmonary resuscitation is often performed in compromised conditions and for long periods.
  
  
  OBJECTIVE
  To compare energy expenditure, compression effectiveness, and kinetics of the spine during simulated chest compression with the rescuer in different positions.
  
  
  METHODS
  A 3-group design with 36 nurses (26 females) and 20 male emergency medical technicians was used. Participants performed chest compressions on a mannequin while kneeling on the floor, standing, or kneeling on the bed at the edge of the mattress (bed mount). Oxygen consumption and effectiveness of chest compression were recorded. Muscle moment and power at the lumbosacral joint were determined by recording motions of the lower limbs and pelvis with an electromagnetic tracking device and measuring ground reaction forces with a force plate.
  
  
  RESULTS
  A total of 80% of chest compressions delivered by male rescuers (vs 40% delivered by females) were effective, irrespective of position. Male rescuers consumed less oxygen when delivering chest compressions while standing than while kneeling (P = .03), but effective compression ratio also was lower. In female rescuers, effective compressions correlated positively with oxygen consumption in the standing (r = 0.42, P = .04) and bed-mount (r = 0.53, P = .008) positions. Administering chest compressions while standing involved a larger moment magnitude and required more power than doing so while kneeling.
  
  
  CONCLUSIONS
  Administering chest compressions while standing demands more power but consumes less oxygen than doing so while kneeling, perhaps because fewer cardiac compressions delivered while standing are effective.
authors.affiliation: Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong. rsajones@polyu.edu.hk
authors.forename: Alice Y M
authors.initials: AY
authors.lastname: Jones
authors.forename: Raymond Y W
authors.initials: RY
authors.lastname: Lee
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D019245:Compressive Strength; D004634:Emergency Medical Technicians; D004636:Emergency Service, Hospital; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008348:Manikins; D009726:Nurses; D010101:Oxygen Consumption / Q000502:physiology; D010865:Pilot Projects; D011187:Posture; D012737:Sex Factors; D013131:Spine / Q000502:physiology*