EFFECTS OF DANTROLENE ON COOLING TIMES AND CARDIOVASCULAR PARAMETERS IN AN IMMATURE PORCINE MODEL OF HEATSTROKE

Objective: To evaluate the effects of dantrolene on cooling times and cardiovascular parameters in an immature porcine model of heatstroke. Design: Prospective, randomized, controlled, multigroup study. Setting : Research animal laboratory. Subjects: Yorkshire piglets (n = 16), 4 to 5 wks of age, 3.5 to 4.5 kg of body weight. Interventions: Animals were slowly heated with a radiant heat source to 43 degrees C and then maintained at this temperature for 30 mins. The animals were then rem oved from the heat source and randomized into one of four groups to re ceive either conventional cooling methods consisting of fluid resuscit ation with 0.9% sodium chloride solution, sponging with room temperatu re water, mechanical fanning, and gastric lavage with iced 0.9% sodium chloride solution (group 1), conventional cooling methods and dantrol ene (group 2), conventional cooling methods and dantrolene's vehicle m annitol (group 3), or no treatment (group 4). Cooling times, defined a s the time required to reach a core body temperature of 38.5 degrees C , and cardiovascular parameters for each group were then compared. Mea surements and Main Results: Animals in groups 1, 2, and 3 had signific antly (p < .05) lower core body temperatures than animals that receive d no treatment at the conclusion of the experiment. Piglets in groups 2 and 3 had faster cooling times than piglets in group 1 (p < .05). Ho wever, there was no statistically significant difference in cooling ti mes between the animals in groups 2 and 3. There were no statistically significant differences in heart rate, mean arterial pressure, centra l venous pressure, pulmonary artery occlusion pressure, or systemic va scular resistance index between animals in groups 1, 2, or 3. Group 3 piglets had higher cardiac indices and stroke indices than the piglets in the other groups (p < .05). Conclusions: Therapeutic interventions with conventional cooling or conventional cooling and dantrolene prov ided significant improvement in cardiovascular function in an immature porcine heatstroke model. Dantrolene, given with conventional cooling methods, offered no significant improvement in cardiovascular paramet ers compared with conventional cooling methods alone. Dantrolene signi ficantly shortened the cooling time compared with conventional cooling but did not significantly shorten the cooling time compared with its vehicle, mannitol. Although dantrolene significantly shortened the coo ling time, it did not appear to be superior compared with conventional cooling methods in treating heatstroke in this immature porcine heats troke model.