title: Improving standard cardiopulmonary resuscitation with an inspiratory impedance threshold valve in a porcine model of cardiac arrest.
abstract: To improve the efficiency of standard cardiopulmonary resuscitation (CPR), we evaluated the potential value of impeding respiratory gas exchange selectively during the decompression phase of standard CPR in a porcine model of ventricular fibrillation. After 6 min of untreated cardiac arrest, anesthetized farm pigs weighing 30 kg were randomized to be treated with either standard CPR with a sham valve (n = 11) or standard CPR plus a functional inspiratory impedance threshold valve (ITV(TM)) (n = 11). Coronary perfusion pressure (CPP) (diastolic aortic minus right atrial pressure) was the primary endpoint. Vital organ blood flow was assessed with radiolabeled microspheres after 6 min of CPR, and defibrillation was attempted 11 min after starting CPR. After 2 min of CPR, mean +/- SEM CPP was 14 +/- 2 mm Hg with the sham valve versus 20 +/- 2 mm Hg in the ITV group (P < 0.006). Significantly higher CPPs were maintained throughout the study when the ITV was used. After 6 min of CPR, mean +/- SEM left ventricular and global cerebral blood flows were 0.10 +/- 0.03 and 0.19 +/- 0.03 mL. min(-1). g(-1) in the Control group versus 0.19 +/- 0.03 and 0.26 +/- 0.03 mL. min(-1). g(-1) in the ITV group, respectively (P < 0.05). Fifteen minutes after successful defibrillation, 2 of 11 animals were alive in the Control group versus 6 of 11 in the ITV group (not significant). In conclusion, use of an inspiratory impedance valve during standard CPR resulted in a marked increase in CPP and vital organ blood flow after 6 min of cardiac arrest.
authors.affiliation: Department of Medicine, Cardiovascular Division, Cardiac Arrhythmia Center, University of Minnesota, Minneapolis 55455, USA. lurie002@tc.umn.edu
authors.forename: K G
authors.initials: KG
authors.lastname: Lurie
authors.forename: W G
authors.initials: WG
authors.lastname: Voelckel
authors.forename: T
authors.initials: T
authors.lastname: Zielinski
authors.forename: S
authors.initials: S
authors.lastname: McKnite
authors.forename: P
authors.initials: P
authors.lastname: Lindstrom
authors.forename: C
authors.initials: C
authors.lastname: Peterson
authors.forename: V
authors.initials: V
authors.lastname: Wenzel
authors.forename: K H
authors.initials: KH
authors.lastname: Lindner
authors.forename: N
authors.initials: N
authors.lastname: Samniah
authors.forename: D
authors.initials: D
authors.lastname: Benditt
mesh_terms: D000818:Animals; D001784:Blood Gas Analysis; D016887:Cardiopulmonary Resuscitation / Q000295:instrumentation*; D006323:Heart Arrest / Q000628:therapy*; D006439:Hemodynamics / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D012121:Respiration, Artificial / Q000295:instrumentation*; D015656:Respiratory Mechanics / Q000502:physiology; D013552:Swine