Cardiac arrest: High-energy shocks were not clearly better than low-energy shocks.

Clinical bottom line (level 2b-)

  1. Patients with ventricular fibrillation who were given a high-energy shock (400+ J), had no clear difference in defibrillation or discharge from hospital than those given a low-energy shock (200-299J).
  2. Patients given an intermediate-energy shock (300 to 399J)had no clear difference in defibrillation or discharge from hospital than those given a low-energy shock.
Morgan et al: Mayo Clinic Proceedings 1984; 59: 829-834
Expires October 2003

The study

Single-blinded ?concealed quasi-randomised trial with intention-to-treat
Setting: multicentre, USA

101 patients (aged range 11 to 94 years; mean 65, 73% male) ventricular fibrillation and underwent electrical shock

Excluded if
  • ventricular tachycardia or flutter without fibrillation
  • resident in coronary intensive care units
  • incomplete data recorded on protocol forms


    • Note:
  • one patient was entered into the trial twice.
  • prospective trial


    • Control Group: (n = 33, 33 analysed): low-energy defibrillation-200-299 J
    Experimental Group: (n = 36, 36 analysed): intermediate-energy defibrillation- 300-399 J
    Experimental Group: (n = 32, 32 analysed): high-energy defibrillation- 400-499 J
    Electrical shocks were delivered using LifePak 6 or 911 defibrillators. All shocks were delivered by means of conventional electrodes placed on the chest wall at the right upper apex at the fifth interspace at the anterior axillary line. Electrode paste, commercial pads or saline-soaked gauze was placed between the electrodes and the skin.
    100% followed for ?
    Outcome notes:
    • successful defibrillation with shock 1 (versus high-energy shock) : ventricular fibrillation converted to any other rhythm

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    successful defibrillation with shock 1 (versus high-energy shock) unknown 13
    (39.39%)    		 18
    (56.25%)    		 28%
    (-17% to 55%)    		 16.86%
    (-7.09% to 40.80%)    		 6
    (NNT = 2 to infinity;
    NNH = 14 to infinity)
    discharged from hospital (versus high energy shock) unknown 4
    (12.1%)    		 3
    (9.38%)    		 -3%
    (-22% to -2%)    		 -2.75%
    (-17.78% to 12.29%)    		 -36
    (NNT = 8 to infinity;
    NNH = 6 to infinity)
    successful defibrillation by shock 1 (versus intermediate-energy shock) unknown 13
    (39.4%)    		 21
    (58.33%)    		 31%
    (-10% to 57%)    		 18.94%
    (-4.24% to 42.12%)    		 5
    (NNT = 2 to infinity;
    NNH = 24 to infinity)
    discharged from hospital (versus intermediate-energy shock) unknown 4
    (12.1%)    		 1
    (2.78%)    		 -11%
    (-27% to 4%)    		 -9.34%
    (-21.71% to 3.02%)    		 -11
    (NNT = 33 to infinity;
    NNH = 5 to infinity)

    Comments

    1. This small study does not support the use of higher levels of electrical energy for the initial treatment of ventricular fibrillation.
    2. The study was too small to show any clear differences between the two groups.
    3. Emergency resuscitation teams consisted of a medical resident, anaesthesiology resident, pharmacist and two to four nurses, who are all trained in basic cardiopulmonary resuscitation; in addition, the medical and anaesthesiology residents are certified in advanced cardiac life support according to American Heart Association standards.

    Citation

    1. Morgan JP, Hearne SF, Raizes GS, et al: High-energy versus low-energy defibrillation: Experience in patients (excluding those in the intensive care unit) at Mayo Clinic-affiliated hospitals. Mayo Clinic Proceedings 1984; 59: 829-834
    Contributor: Clare Wotton and Musab Hayatli, October 1999
    Reviewer: Kenneth Ballew

    Clinical Question.
    Patient ventricular fibrillation
    Intervention or Exposure high-energy defibrillation
    Comparison low-energy defibrillation
    Outcome survival