Study objective: Assisted ventilation may adversely affect out-of-hospital cardiac arrest outcomes. Passive ventilation offers an alternate method of oxygen delivery for these patients. We compare the adjusted neurologically intact survival of out-of-hospital cardiac arrest patients receiving initial passive ventilation with those receiving initial bag-valve-mask ventilation.
Methods: The authors performed a retrospective analysis of statewide out-of-hospital cardiac arrests between January 1, 2005, and September 28, 2008. The analysis included consecutive adult out-of-hospital cardiac arrest patients receiving resuscitation with minimally interrupted cardiopulmonary resuscitation (CPR) consisting of uninterrupted preshock and postshock chest compressions, initial noninvasive airway maneuvers, and early epinephrine. Paramedics selected the method of initial noninvasive ventilation, consisting of either passive ventilation (oropharyngeal airway insertion and high-flow oxygen by nonrebreather facemask, without assisted ventilation) or bag-valve-mask ventilation (by paramedics at 8 breaths/min). The authors determined adjusted neurologically intact survival from hospital and public records and by telephone interview and mail questionnaire. The authors compared adjusted neurologically intact survival between ventilation techniques by using generalized estimating equations.
Results: Among the 1,019 adult out-of-hospital cardiac arrest patients in the analysis, 459 received passive ventilation and 560 received bag-valve-mask ventilation. Adjusted neurologically intact survival after witnessed ventricular fibrillation/ventricular tachycardia out-of-hospital cardiac arrest was higher for passive ventilation (39/102; 38.2%) than bag-valve-mask ventilation (31/120; 25.8%) (adjusted odds ratio [OR] 2.5; 95% confidence interval [CI] 1.3 to 4.6). Survival between passive ventilation and bag-valve-mask ventilation was similar after unwitnessed ventricular fibrillation/ventricular tachycardia (7.3% versus 13.8%; adjusted OR 0.5; 95% CI 0.2 to 1.6) and nonshockable rhythms (1.3% versus 3.7%; adjusted OR 0.3; 95% CI 0.1 to 1.0).
Conclusion: Among adult, witnessed, ventricular fibrillation/ventricular tachycardia, out-of-hospital cardiac arrest resuscitated with minimally interrupted cardiac resuscitation, adjusted neurologically intact survival to hospital discharge was higher for individuals receiving initial passive ventilation than those receiving initial bag-valve-mask ventilation.