title: A trial of an impedance threshold device in out-of-hospital cardiac arrest.
abstract: BACKGROUND
  The impedance threshold device (ITD) is designed to enhance venous return and cardiac output during cardiopulmonary resuscitation (CPR) by increasing the degree of negative intrathoracic pressure. Previous studies have suggested that the use of an ITD during CPR may improve survival rates after cardiac arrest.
  
  
  METHODS
  We compared the use of an active ITD with that of a sham ITD in patients with out-of-hospital cardiac arrest who underwent standard CPR at 10 sites in the United States and Canada. Patients, investigators, study coordinators, and all care providers were unaware of the treatment assignments. The primary outcome was survival to hospital discharge with satisfactory function (i.e., a score of ≤3 on the modified Rankin scale, which ranges from 0 to 6, with higher scores indicating greater disability).
  
  
  RESULTS
  Of 8718 patients included in the analysis, 4345 were randomly assigned to treatment with a sham ITD and 4373 to treatment with an active device. A total of 260 patients (6.0%) in the sham-ITD group and 254 patients (5.8%) in the active-ITD group met the primary outcome (risk difference adjusted for sequential monitoring, -0.1 percentage points; 95% confidence interval, -1.1 to 0.8; P=0.71). There were also no significant differences in the secondary outcomes, including rates of return of spontaneous circulation on arrival at the emergency department, survival to hospital admission, and survival to hospital discharge.
  
  
  CONCLUSIONS
  Use of the ITD did not significantly improve survival with satisfactory function among patients with out-of-hospital cardiac arrest receiving standard CPR. (Funded by the National Heart, Lung, and Blood Institute and others; ROC PRIMED ClinicalTrials.gov number, NCT00394706.).
authors: Department of Emergency Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA. taufderh@mcw.edu
authors: Tom P
authors: TP
authors: Aufderheide
authors: Graham
authors: G
authors: Nichol
authors: Thomas D
authors: TD
authors: Rea
authors: Siobhan P
authors: SP
authors: Brown
authors: Brian G
authors: BG
authors: Leroux
authors: Paul E
authors: PE
authors: Pepe
authors: Peter J
authors: PJ
authors: Kudenchuk
authors: Jim
authors: J
authors: Christenson
authors: Mohamud R
authors: MR
authors: Daya
authors: Paul
authors: P
authors: Dorian
authors: Clifton W
authors: CW
authors: Callaway
authors: Ahamed H
authors: AH
authors: Idris
authors: Douglas
authors: D
authors: Andrusiek
authors: Shannon W
authors: SW
authors: Stephens
authors: David
authors: D
authors: Hostler
authors: Daniel P
authors: DP
authors: Davis
authors: James V
authors: JV
authors: Dunford
authors: Ronald G
authors: RG
authors: Pirrallo
authors: Ian G
authors: IG
authors: Stiell
authors: Catherine M
authors: CM
authors: Clement
authors: Alan
authors: A
authors: Craig
authors: Lois
authors: L
authors: Van Ottingham
authors: Terri A
authors: TA
authors: Schmidt
authors: Henry E
authors: HE
authors: Wang
authors: Myron L
authors: ML
authors: Weisfeldt
authors: Joseph P
authors: JP
authors: Ornato
authors: George
authors: G
authors: Sopko
mesh_terms: D000368:Aged; D016887:Cardiopulmonary Resuscitation / Q000295:instrumentation*; D004632:Emergency Medical Services; D005260:Female; D006801:Humans; D008297:Male; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality / Q000628:therapy*; D016896:Treatment Outcome