Preliminary study of hypothermia induced by intraperitoneal cooling in rabbits after cardiopulmonary resuscitation

Abstract

Objective To explore the safety and rate of intraperitoneal cooling in rabbits after cardiopulmonary resuscitation(CPR). Method There were two experiments. In the experiment one: 15 healthy adult NewZealand rabbits were divided into five groups as per the various amounts, 30, 40, 60, 80, and 100 mL/kg, of priming volume of 4 ℃ cold balanced salts solution injected into peritoneal cavity of rabbits. After injection of priming cold solution, the tympanic temperature between 33 ℃～ 35 ℃. For the maintenance of this mild hypothermia, a intraperitoneal infusion device(patent number ZL200820201265) was connected to the rabbits. The rabbits were rewarmed by using the same device after 12-hour hypothermia. The biochemical parameters were assayed during the experiment. After the rabbits were sacrificed, the liver, ileocecal junction of intestine and kidneys were removed to fix them in 3 % formalin, and examined by using H.E. staining. In the experiment two, another 12 healthy adult New Zealand rabbits were induced into ventricular fibrillation by alternating electric current and then gave CPR for 2 minutes. After return of spontaneous circulation(ROSC), the priming volume of 4 ℃ cold liquid was infused into peritoneal cavity of rabbits, and then the rabbits were connected to the intraperitoneal cooling device to maintain hypothermia for 12 hours. Matched-pairs t test was used for the comparison of biomarkers before and after intraperitoneal cooling. A two-tailed value of P < 0.05 was considered statistically significant. Results In the experiment one, the tympanic temperature of rabbits with priming volume of 80 mL/kg cold solution was decreased quickly reaching the target temperature in(30±2.00) minutes. During the induction of hypothermia, the intraperitoneal temperature reached the target temperature in less than 10 minutes, and was 1 -2℃ lower than the tympanic temperature during the maintenance of hypothermia. The intraperitoneal cooling did not cause damage in the liver, ileocecal junction of intestine and kidney, and did not alter the biomarkers. In the experiment two, the tympanic temperature of rabbits after ROSC was decreased quickly after intraperitoneal infusion of 80 mL/kg 4 ℃ cold solution, and reached the target temperature in(26.00±6.99) minutes, and the intraperitoneal temperature was lowered to reach the target temperature in less than 10 minutes. This cooling method after CPR didn' t disturbance water-electrolyte and acid-base balance. Conclusions The intraperitoneal cooling can safely and quickly induce hypothermia after CPR in rabbits. Key words: Hypothermia; Peritoneal cavity cooling; Cardiopulmonary resuscitation; Rabbit