Current-based transthoracic defibrillation.
This study examines in a prospective, multicenter trial the feasibility and advantage of current-based, transthoracic defibrillation. Current-based, damped, sinusoidal waveform shocks of 18, 25, 30, 35, or 40 amperes (A) were administered beginning with 25 A for polymorphic ventricular tachycardia (VT) and ventricular fibrillation (VF) or 18 A for monomorphic VT; success rates were compared with those of energy-based shocks beginning at 200 J for VF/polymorphic VT and 100 J for VT. The current-based shocks were delivered from custom-modified defibrillators that determined impedance in advance of any shock using a "test-pulse" technique; the capacitor then charged to the exact energy necessary to deliver the operator-selected current against the impedance determined by the defibrillator. Three hundred sixty-two patients received > 1 shock for VF, polymorphic VT, or monomorphic VT: 569 current- based shocks and 420 energy-based shocks. Current-based shocks of 35/40 A achieved success rates of up to 74% for VF/polymorphic VT; 30 A shocks terminated 88% of monomorphic VT episodes. Energy-based shocks of 300 J terminated 72% of VF/polymorphic VT; 200-J shocks terminated 89% of monomorphic VT. We could not demonstrate a significant increase in the success rate of current-based shocks over energy-based shocks for patients with high transthoracic impedance; this may be due to inadequate sample size. Thus, current-based defibrillation is clinically feasible and effective. A larger study will be needed to test whether current-based defibrillation is superior to energy-based defibrillation.
Kerber
R E
RE
University of Iowa Hospitals & Clinics, Iowa City, USA.
Kieso
R A
RA
Kienzle
M G
MG
Olshansky
B
B
Waldo
A L
AL
Carlson
M D
MD
Wilber
D J
DJ
Aschoff
A M
AM
Birger
S
S
Charbonnier
F
F
D004554:Electric Countershock / Q000379:methods*; D017097:Electric Impedance; D005240:Feasibility Studies; D006801:Humans; D011446:Prospective Studies; D017180:Tachycardia, Ventricular / Q000628:therapy*; D014693:Ventricular Fibrillation / Q000628:therapy*