title: Effect of rescue breathing during cardiopulmonary resuscitation on lung function after restoration of spontaneous circulation in a porcine model of prolonged cardiac arrest.
abstract: OBJECTIVE
  The destruction of the pulmonary structure after cardiopulmonary resuscitation may lead to lung function breakdown. The aim of this study was to investigate lung function after cardiopulmonary resuscitation and the influence of rescue breathing on lung function.
  
  
  METHODS
  Prospective, randomized animal study.
  
  
  METHODS
  A university animal research laboratory.
  
  
  METHODS
  Twenty-eight male domestic pigs weighing 30 ± 2 kg.
  
  
  METHODS
  The animals were randomized into three groups: continuous compressions (n = 12), 30:2 compression/rescue ventilation cardiopulmonary resuscitation (n = 12), and sham cardiopulmonary resuscitation (n = 4). Ventricular fibrillation was induced in the continuous compressions and compression/rescue ventilation groups.
  
  
  RESULTS
  Cardiac output, extravascular lung water, and airway resistance were measured at baseline and 1, 2, and 4 hrs after restoration of spontaneous circulation. Thoracopulmonary compliance, lower inflection point, and dead space were calculated. Lung ventilation/perfusion scans with Tc were performed 48 hrs before the experiment and 24 hrs after restoration of spontaneous circulation. Conventional histopathology evaluation was performed. Dead space, airway resistance, lower inflection point, and extravascular lung water significantly increased and compliance decreased after restoration of spontaneous circulation in the continuous compressions and compression/rescue ventilation groups. Lung injury was more severe in the continuous compressions group. Significant differences were found between the two groups in the three time points after restoration of spontaneous circulation (p < 0.05). Variables of the sham cardiopulmonary resuscitation group remained stable during the whole protocol. Poor ventilation/perfusion and mismatch were found after restoration of spontaneous circulation, but the injury was mitigated in the compression/rescue ventilation group. Histopathology injury in the compression/rescue ventilation group was also improved.
  
  
  CONCLUSIONS
  Appropriate rescue breathing during cardiopulmonary resuscitation does not influence the prognosis of cardiac arrest or the hemodynamics after restoration of spontaneous circulation but can improve lung function and alleviate lung injury.
authors.affiliation: Department of Emergency Medicine, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Chaoyang District, Beijing, China.
authors.forename: Shuo
authors.initials: S
authors.lastname: Wang
authors.forename: Jun-Yuan
authors.initials: JY
authors.lastname: Wu
authors.forename: Zhi-Jun
authors.initials: ZJ
authors.lastname: Guo
authors.forename: Chun-Sheng
authors.initials: CS
authors.lastname: Li
mesh_terms: D055371:Acute Lung Injury / Q000209:etiology / Q000517:prevention & control*; D000818:Animals; D016887:Cardiopulmonary Resuscitation / Q000009:adverse effects / Q000379:methods*; D006323:Heart Arrest / Q000628:therapy*; D006439:Hemodynamics; D008297:Male; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D011897:Random Allocation; D012129:Respiratory Function Tests; D013552:Swine