ELECTRICAL DEFIBRILLATION TO TREAT VENTRICULAR FIBRILLATION IN A CONTROLLED, NON-RANDOMIZED PILOT IN SWINE. KW V~n
MgtQr, HT Swanson. S Sheos. D Ross. PG Herch. K Buechter. N McSwain. F Kriedt. SF Gottlieb. R Gonzalez. G Anstadt. Baromedical Reseamh Institute. New Orleans. Louisiana 70114.

In a controlled, matched, non-randomized pilot study, the safety and efficacy of resuscitation in a hyperbaric chamber was explored with swine. 6 swine were arrested in a 60" double-lock HBO chamber on surface by alternating current applied to epicardium by catheter wire after mid sternal thoracotomy followed by pericardotomy. After 15 mine of V-fib (VI=), the animals had a direct mechanical ventricular assistance device (DMVAD) applied over the pericardotomized ventricles.

The animals were taken to 165 fsw, 60 few, or left on surface. 20 minutes after induction of VF the animals were placed by ventilator on 100% OZ. 25 minutes post-arrest, the animals had the DMVAD removed and, if necessary, were electrically defibrillated (ED) by heart paddles applied directly to the heart wall. Results were as follows:

Surfeoe it 92Surfeoe it 10060 few It 9660 few it 98165 few ~ 88165 f.w it 101Total Time of FibDefib FailedDefib Failed26 mine1 S - 25 mine15 - 26 mine49 mineRequired time for defib attempt--1 rain$pon ROSCSpon ROSCROSC et 24 mineDefib by ED Attempts.2 tries (20 end 50 J) ureeolvable eeystole6 triu {20, 35, 50 J, X 4) unrelmlvable' uystole.1 try (20 J) Suoeesefu I DefibSport ROSC No ED requiredNo ED Required6 ED's within firet 35 min felled. Spon ROSC at 49 minOnen chest ED on swine ventilated with 100¶O. can be accomplished safely at
0, 60, and 165 fsw in a hyperbaric chamber under our conditions. ED appears to be more efficacious in promoting defib at increased O2 pressures afforded at 60 fsw and at 165 fsw than at surface following prolonged cardiac arrest.