Decompression-triggered positive-pressure ventilation during cardiopulmonary resuscitation improves pulmonary gas exchange and oxygen uptake.
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.


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 (PaO(2)) 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 VA/Q 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 (VO(2)) 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 PaO(2) and VO(2).
Kleinsasser
Axel
A
Department of Medicine, Division of Physiology, University of California, San Diego 92093-0623, USA. akleinsasser@ucsd.edu
Lindner
Karl H
KH
Schaefer
Andreas
A
Loeckinger
Alexander
A
D000818:Animals; D001158:Arteries / Q000737:chemistry; D001784:Blood Gas Analysis; D016887:Cardiopulmonary Resuscitation; D006323:Heart Arrest / Q000175:diagnosis / Q000378:metabolism / Q000628:therapy*; D006439:Hemodynamics; D008168:Lung / Q000098:blood supply / Q000378:metabolism / Q000503:physiopathology; D005741:Noble Gases / Q000032:analysis; D010101:Oxygen Consumption; D011175:Positive-Pressure Respiration / Q000379:methods*; D011659:Pulmonary Gas Exchange; D012129:Respiratory Function Tests; D013552:Swine
D005741:Noble Gases