title: Reduced effectiveness of vasopressin in repeated doses for patients undergoing prolonged cardiopulmonary resuscitation.
abstract: BACKGROUND
  The efficacy of repeated administration of vasopressin alone during prolonged cardiopulmonary resuscitation (CPR) remains unconfirmed. This study was conducted to estimate the effectiveness of the repeated administration of vasopressin vs. epinephrine for cardiopulmonary arrest (CPA) patients receiving prolonged CPR.
  
  
  METHODS
  We conducted a prospective randomized controlled study on patients who experienced out-of-hospital CPA. The patients were randomly assigned to receive a maximum of four injections of either 40IU of vasopressin (vasopressin group) or 1mg of epinephrine (epinephrine group) immediately after emergency room (ER) admission. Patients who received vasopressors before ER admission or suffered non-cardiogenic CPA were excluded after randomization.
  
  
  RESULTS
  In total, 336 patients were enrolled (vasopressin group, n=137; epinephrine group, n=118). No differences were found between these groups (vasopressin group vs. epinephrine group) in the rates of return of spontaneous circulation (ROSC) (28.7% vs. 26.6%), 24-h survival (16.9% vs. 20.3%), or survival to hospital discharge (5.6% vs. 3.8%). In a subgroup analysis by the Fisher's exact test, the rate of ROSC was higher in the vasopressin group than in the epinephrine group, among the patients whose arrests were witnessed (48.1% vs. 27.8%, p=0.010) or who received bystander CPR (68.0% vs. 38.5%, p=0.033). When the independent predictors of ROSC were calculated in the subgroup analysis, however, vasopressin administration (Odds ratio: 0.87-0.28) did not affect the outcome.
  
  
  CONCLUSIONS
  This is the first report of a possible vasopressin-alone resuscitation without additional epinephrine. However, repeated injections of either vasopressin or epinephrine during prolonged advanced cardiac life support resulted in comparable survival.
authors.affiliation: Department of Acute Medicine, Nihon University School of Medicine, Oyaguchi Kamimachi, Itabashi-ku, Tokyo, Japan. mukoyama@f8.dion.ne.jp
authors.forename: Takeo
authors.initials: T
authors.lastname: Mukoyama
authors.forename: Kosaku
authors.initials: K
authors.lastname: Kinoshita
authors.forename: Ken
authors.initials: K
authors.lastname: Nagao
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Tanjoh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016887:Cardiopulmonary Resuscitation; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006323:Heart Arrest / Q000401:mortality* / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome; D014662:Vasoconstrictor Agents / Q000008:administration & dosage*; D014667:Vasopressins / Q000008:administration & dosage*
chemical_list: D014662:Vasoconstrictor Agents; D014667:Vasopressins