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(Circulation. 2002;106:373.)
© 2002 American Heart Association, Inc.

Basic Science Reports

Decompression-Triggered Positive-Pressure Ventilation During Cardiopulmonary Resuscitation Improves Pulmonary Gas Exchange and Oxygen Uptake

Axel Kleinsasser, MD; Karl H. Lindner, MD; Andreas Schaefer, MD; Alexander Loeckinger, MD

From the Department of Medicine, Division of Physiology, University of California, San Diego (A.K.), and the Department of Anesthesiology and Critical Care Medicine, Leopold-Franzens University, Innsbruck, Austria (K.H.L., A.S., A.L.).

Correspondence to Axel Kleinsasser, MD, Department of Medicine, Division of Physiology, University of California, San Diego, 9500 Gilman Dr, CA 92093-0623A. E-mail akleinsasser{at}ucsd.edu

Background— Intermittent positive-pressure ventilation (IPPV) is the "gold standard" of ventilation during cardiopulmonary resuscitation (CPR), but continuous positive airway pressure (CPAP) is increasingly discussed as an alternative. This study investigated hemodynamics and pulmonary gas exchange applying CPAP enhanced with pressure support ventilation (CPAP^PSV) during CPR.

Methods and Results— Twenty-four pigs were subjected to ventricular fibrillation and CPR with CPAP^PSV, CPAP, or IPPV. Measurements were taken before (hemodynamics, blood gases, inert gas measurements) and 10 (hemodynamics, blood gases) and 20 (hemodynamics, blood gases, inert gas measurements) minutes after induction of ventricular fibrillation. Although no significant intergroup differences in hemodynamics were found, arterial partial pressure of oxygen (PaO₂) was significantly higher during CPAP^PSV compared with CPAP or IPPV (98±10, 61±27, and 71±30 mm Hg, respectively, P<0.05). CPAP^PSV resulted in an alveolar-arterial partial pressure of oxygen difference of 56±17 mm Hg, whereas during CPAP, 83±21 mm Hg was detected, and during IPPV, 98±29 mm Hg was detected (P<0.05). Pulmonary blood flow to lung units with a normal A/ ratio in percent of cardiac output was 76±17% during CPAP^PSV, 61±21% during CPAP (P<0.01), and 54±13% during IPPV (P<0.01). Oxygen uptake (O₂) was significantly higher during CPAP^PSV than with the other ventilation modes (P<0.05) and comparable to the baseline value in intragroup comparison. Return of spontaneous circulation was recorded in 8 of 8 animals in the CPAP^PSV group, in 6 of 8 in the CPAP group, and in 3 of 8 in the IPPV group.

Conclusions— CPAP^PSV provides a straightforward and effective alternative to IPPV or CPAP during CPR that provides significantly higher PaO₂ and O₂.

Key Words: heart arrest • cardiopulmonary resuscitation • lung • oxygen