title: The effects of nifedipine on ventricular fibrillation mean frequency in a porcine model of prolonged cardiopulmonary resuscitation.
abstract: We assessed the effects of a calcium channel blocker versus saline placebo on ventricular fibrillation mean frequency and hemodynamic variables during prolonged cardiopulmonary resuscitation (CPR). Before cardiac arrest, 10 animals were randomly assigned to receive either nifedipine (0.64 mg/kg; n = 5) or saline placebo (n = 5) over 10 min. Immediately after drug administration, ventricular fibrillation was induced. After 4 min of cardiac arrest and 18 min of basic life support CPR, defibrillation was attempted. Ninety seconds after the induction of cardiac arrest, ventricular fibrillation mean frequency was significantly (P < 0.01) increased in nifedipine versus placebo pigs (mean +/- SD: 12.4 +/- 2.1 Hz versus 8 +/- 0.7 Hz). From 2 to 18.5 min after the induction of cardiac arrest, no differences in ventricular fibrillation mean frequency were detected between groups. Before defibrillation, ventricular fibrillation mean frequency was significantly (P < 0.05) increased in nifedipine versus placebo animals (9.7 +/- 1.2 Hz versus 7.1 +/- 1.3 Hz). Coronary perfusion pressure was significantly lower in the nifedipine than in the placebo group from the induction of ventricular fibrillation to 11.5 min of cardiac arrest; no animal had a return of spontaneous circulation after defibrillation. In conclusion, nifedipine, but not saline placebo, prevented a rapid decrease of ventricular fibrillation mean frequency after the induction of cardiac arrest and maintained ventricular fibrillation mean frequency at approximately 10 Hz during prolonged CPR; this was nevertheless associated with no defibrillation success.
  
  
  CONCLUSIONS
  This study evaluates the effects of a calcium channel blocker on ventricular fibrillation mean frequency, hemodynamic variables, and resuscitability during prolonged cardiopulmonary resuscitation (CPR) in pigs. Nifedipine, but not saline placebo, prevented a rapid decrease of ventricular fibrillation mean frequency after the induction of cardiac arrest and maintained ventricular fibrillation mean frequency at approximately 10 Hz during prolonged CPR but did not improve resuscitability.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Leopold-Franzens-University, Innsbruck, Austria.
authors.forename: Karl H
authors.initials: KH
authors.lastname: Stadlbauer
authors.forename: Klaus
authors.initials: K
authors.lastname: Rheinberger
authors.forename: Volker
authors.initials: V
authors.lastname: Wenzel
authors.forename: Claus
authors.initials: C
authors.lastname: Raedler
authors.forename: Anette C
authors.initials: AC
authors.lastname: Krismer
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Strohmenger
authors.forename: Sven
authors.initials: S
authors.lastname: Augenstein
authors.forename: Horst G
authors.initials: HG
authors.lastname: Wagner-Berger
authors.forename: Wolfgang G
authors.initials: WG
authors.lastname: Voelckel
authors.forename: Karl H
authors.initials: KH
authors.lastname: Lindner
authors.forename: Anton
authors.initials: A
authors.lastname: Amann
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000627:therapeutic use*; D016887:Cardiopulmonary Resuscitation; D003326:Coronary Circulation / Q000187:drug effects; D004562:Electrocardiography; D006323:Heart Arrest / Q000503:physiopathology; D006439:Hemodynamics / Q000187:drug effects; D009543:Nifedipine / Q000627:therapeutic use*; D013552:Swine; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000517:prevention & control*
chemical_list: D002121:Calcium Channel Blockers; D009543:Nifedipine