Successful defibrillation in water: a preliminary study.

Mild hypothermia (32-34 deg C) treatment alleviates vital organ damage after cardiac arrest. A new cooling device, the Thermosuit operates by applying of a thin layer of water directly to the body surface. Hypothermic patients may experience sequential fibrillation. Therefore, we examined whether defibrillation could be administered safely and effectively in water. A 35 kg swine was anesthetized and placed inside the Thermosuit system. This consists of a water containing surround and pumping system. Conventional AED disposable defibrillation electrodes were applied to the animal's chest. Fibrillation was created by applying a 50-volt signal to a pacing wire introduced into the heart. Following a 30-second period of fibrillation, defibrillation was attempted using Medtronic AED 1000 defibrillator. Defibrillation voltage and current were measured. There were three test cases: dry in the system, wet in the functioning system, and damp. Cooling water in the system was contaminated with saline to simulate potential conditions in clinical application. In each fibrillation-defibrillation sequence, the heart was restarted successfully; this required less than 220 joules. Only a small difference was measured in the overall defibrillation voltage and current as applied to the electrodes for the different cases. Thus, underwater defibrillation is safe and can be performed effectively.

Phased chest and abdominal compression-decompression. A new option for cardiopulmonary resuscitation.

BACKGROUND: We describe a new manual method of phased chest and abdominal compression-decompression with a Lifestick resuscitator for cardiopulmonary resuscitation (CPR). METHODS AND RESULTS: Ventricular fibrillation (VF) was induced in 20 domestic pigs. After either 5 or 7 minutes of untreated VF, either phased chest and abdominal compression-decompression (Lifestick resuscitator) or precordial compression was initiated. Defibrillation was attempted at 2 minutes after the start of CPR. For the animals in which VF was untreated for 7 minutes, epinephrine was administered in doses of 20 micrograms/kg at 2 minutes after start of CPR. The coronary perfusion pressure generated by the Lifestick resuscitator was more than twofold greater (P < .01) than that generated by conventional precordial compression. Of 5 control animals, none were resuscitated after 5 minutes of VF. However, each of 5 animals treated with the Lifestick resuscitator was resuscitated (P < .01) and survived after 48 hours (P < .01). When untreated VF was prolonged to 7 minutes and epinephrine was administered, only 2 of the 5 control animals were resuscitated, and none of them survived for more than 4 hours. However, each of the Lifestick-treated animals was resuscitated and survived for more than 48 hours (P < .01). CONCLUSIONS: Phased chest and abdominal compression-decompression substantially increased hemodynamic efficacy of CPR and outcome in terms of successful resuscitation, 48-hour survival, and cerebral recovery.