title: Use of an inspiratory impedance valve improves neurologically intact survival in a porcine model of ventricular fibrillation.
abstract: BACKGROUND
  This study evaluated the potential for an inspiratory impedance threshold valve (ITV) to improve 24-hour survival and neurological function in a pig model of cardiac arrest.
  
  
  RESULTS
  Using a randomized, prospective, and blinded design, we compared the effects of a sham versus active ITV on 24-hour survival and neurological function. After 6 minutes of ventricular fibrillation (VF), followed by 6 minutes of cardiopulmonary resuscitation (CPR) with either a sham or an active valve, anesthetized pigs received 3 sequential 200-J shocks. If VF persisted, they received epinephrine (0.045 mg/kg), 90 seconds of CPR, and 3 more 200-J shocks. A total of 11 of 20 pigs (55%) in the sham versus 17 of 20 (85%) in the active valve group survived for 24 hours (P<0.05). Neurological scores were significantly higher with the active valve; the cerebral performance score (1=normal, 5=brain death) was 2.2+/-0.2 with the sham ITV versus 1.4+/-0.2 with the active valve (P<0.05). A total of 1 of 11 in the sham versus 12 of 17 in the active valve group had completely normal neurological function (P<0.05). Peak end-tidal CO2 (PETCO2) values were significantly higher with the active valve (20.4+/-1.0) than the sham (16.8+/-1.5) (P<0.05). PETCO2 >18 mm Hg correlated with increased survival (P<0.05).
  
  
  CONCLUSIONS
  Use of a functional ITV during standard CPR significantly improved 24-hour survival rates and neurological recovery. PETCO2 and systolic blood pressure were also significantly higher in the active valve group. These data support further evaluation of ITV during standard CPR.
authors.affiliation: Cardiac Arrhythmia Center, Department of Medicine, University of Minnesota, Minneapolis 55455, USA. klurie@resqcpr.com
authors.forename: Keith G
authors.initials: KG
authors.lastname: Lurie
authors.forename: Todd
authors.initials: T
authors.lastname: Zielinski
authors.forename: Scott
authors.initials: S
authors.lastname: McKnite
authors.forename: Tom
authors.initials: T
authors.lastname: Aufderheide
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Voelckel
mesh_terms: D000818:Animals; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood / Q000378:metabolism; D016887:Cardiopulmonary Resuscitation / Q000295:instrumentation*; D003326:Coronary Circulation; D005260:Female; D006323:Heart Arrest / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D006439:Hemodynamics; D009420:Nervous System / Q000503:physiopathology*; D010100:Oxygen / Q000097:blood; D015656:Respiratory Mechanics; D013552:Swine; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen