title: Effect of continuous compressions and 30:2 cardiopulmonary resuscitation on global ventilation/perfusion values during resuscitation in a porcine model.
abstract: OBJECTIVE
  Rescue ventilations during bystander resuscitation, although previously considered essential, interrupt the continuity of chest compressions and might have deleterious effects in basic life support. This study was undertaken to analyze the global ventilation/perfusion values of continuous compressions and 30:2 cardiopulmonary resuscitation to determine the effectiveness for each approach in a porcine model of prolonged bystander cardiopulmonary resuscitation for ventricular fibrillation.
  
  
  METHODS
  Prospective, randomized animal study.
  
  
  METHODS
  A university animal research laboratory.
  
  
  METHODS
  Twenty-four male domestic pigs (n = 12/group) weighing 30 ± 2 kg.
  
  
  METHODS
  All animals had ventricular fibrillation induced by programmed electrical stimulation instruments and were randomized into two groups. Continuous compressions or 30:2 compression/rescue ventilation cardiopulmonary resuscitation was performed in each group.
  
  
  RESULTS
  Continuous respiratory variables, hemodynamic parameters, and blood gas analysis outcomes were recorded, and global ventilation/perfusion values were calculated. Alveolar minute volume and global ventilation/perfusion values decreased progressively after ventricular fibrillation, but cardiac output was stable. The global ventilation/perfusion value was higher in the ventilation cardiopulmonary resuscitation group than that in the continuous compression group (p < .0001) and was higher than normal. Coronary perfusion pressure was progressively decreased after 6 mins of cardiopulmonary resuscitation and greatly fluctuated in the ventilation cardiopulmonary resuscitation group. Coronary perfusion pressure was higher in the continuous compression group than that in the ventilation cardiopulmonary resuscitation group after 9 mins of cardiopulmonary resuscitation (p < .05). Values for pH and Pao2 progressively decreased, but there were no significant differences between the two groups, except for pH at 12 mins of cardiopulmonary resuscitation and Paco2 after 3 mins of cardiopulmonary resuscitation.
  
  
  CONCLUSIONS
  In the first 12 mins of cardiopulmonary resuscitation, continuous compressions could maintain relatively better coronary perfusion pressure, Pao2, and global ventilation/perfusion values than 30:2 cardiopulmonary resuscitation. Therefore, rescue ventilation during 12 mins of simulated bystander cardiopulmonary resuscitation did not improve hemodynamics or outcomes compared with compression-only cardiopulmonary resuscitation.
authors.affiliation: Department of Emergency Medicine, Beijing Chaoyang Hospital affiliated with Capital Medical University, Beijing, China.
authors.forename: Shuo
authors.initials: S
authors.lastname: Wang
authors.forename: Chunsheng
authors.initials: C
authors.lastname: Li
authors.forename: Xianfei
authors.initials: X
authors.lastname: Ji
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.forename: Zhiyu
authors.initials: Z
authors.lastname: Su
authors.forename: Junyuan
authors.initials: J
authors.lastname: Wu
mesh_terms: D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000502:physiology; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D004195:Disease Models, Animal; D004562:Electrocardiography; D006323:Heart Arrest / Q000628:therapy*; D006336:Heart Massage / Q000379:methods*; D006439:Hemodynamics / Q000502:physiology; D008297:Male; D012119:Respiration; D013552:Swine / Q000502:physiology; D014692:Ventilation-Perfusion Ratio / Q000502:physiology*