title: A swine model of pseudo-pulseless electrical activity induced by partial asphyxiation.
abstract: BACKGROUND
  The incidence of pulseless electrical activity (PEA) as a presenting rhythm during cardiac arrest is increasing. The current animal models of PEA arrest, post-countershock or total asphyxiation, unreliably generate PEA for a specific time period. Neither of these models predictably generate pseudo-PEA. The purpose of this study was to create an animal model of pseudo-PEA that will allow for a prolonged time period in this arrest state for future research.
  
  
  METHODS
  In a laboratory setting, five ventilated swine on inhaled anesthesia and 100% oxygen with continuous EKG recordings were instrumented with central aortic and venous pressure-transducing catheters. Animals were then switched to intravenous anesthesia while being ventilated with a 16% oxygen/84% nitrogen mix. Continuous EKG, aortic and venous pressures were recorded to a computerized data collection program. Arterial blood gas samples were taken every 10min. Time until onset of pseudo-PEA, duration of pseudo-PEA, and cardiac rhythm during pseudo-PEA were recorded.
  
  
  RESULTS
  Mean time to onset of pseudo-PEA was 80.6+/-47.3min. Mean duration of pseudo-PEA was 18.6+/-6.2min. Mean arterial pH at pseudo-PEA onset was 7.20+/-0.05 with a mean associated base excess of -11.4+/--5.94. No significant differences were noted in other recorded variables.
  
  
  CONCLUSIONS
  Partial asphyxiation using a 16% oxygen/84% nitrogen mix is a reliable laboratory method to create a prolonged state of pseudo-PEA in a swine model. The mechanism generating pseudo-PEA is hypoxemia-induced systemic acidosis. This model will allow sufficient time in this low-flow cardiac state for future research to be conducted.
authors.affiliation: Department of Surgery, Division of Emergency Medicine, University of Colorado at Denver and Health Sciences Center, 12401 East 17th Avenue B215, Aurora, CO 80045, United States. todd.larabee@uchsc.edu
authors.forename: Todd M
authors.initials: TM
authors.lastname: Larabee
authors.forename: Norman A
authors.initials: NA
authors.lastname: Paradis
authors.forename: Jason
authors.initials: J
authors.lastname: Bartsch
authors.forename: Lisa
authors.initials: L
authors.lastname: Cheng
authors.forename: Charles
authors.initials: C
authors.lastname: Little
mesh_terms: D000818:Animals; D001237:Asphyxia / Q000150:complications / Q000503:physiopathology*; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D004195:Disease Models, Animal; D004562:Electrocardiography; D006323:Heart Arrest / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D011674:Pulse; D013552:Swine