Hyperthermic resuscitation is safe and effective after hemorrhagic shock in dogs

To show that resuscitation from hypothermic, hemorrhagic shock using 65 degrees C intravenous fluid results in a more rapid return to euthermia compared with 40 degrees C intravenous fluid, without significant endothelial or hemolytic injury.

Fourteen anesthetized beagles (10-12 kg) were cooled to a core temperature of 30 degrees C and hemorrhaged to a mean arterial pressure of 40 to 45 mm Hg for 30 minutes. The animals were randomized to receive either 65 degrees C or 40 degrees C intravenous fluid through a specially designed catheter at a rate of 80% of their blood volume per hour until euthermic (37 degrees C) or for 2 hours.

Blood pressure, pulmonary artery pressure, heart rate, and core temperature were continuously monitored. Blood samples were collected at baseline, after hemorrhage, 2 hours of resuscitation, and at postmortem examination after 7 days of survival. Laboratory measurements included complete blood count, plasma-free hemoglobin, and osmotic fragility. Values were compared using the Student's paired or unpaired t test with p approximately 0.05 indicating significance. Postmortem examination included light microscopy of the proximal superior vena cava or right atrium.

Animals receiving 65 degrees C intravenous fluid warmed 3.6 degrees C/hour, significantly faster than the 40 degrees C animals (1.9 degrees C/hour). There were no significant differences in plasma-free hemoglobin or osmotic fragility. Endothelial injuries were found in two animals in each group. These defects occurred along the path of catheter insertion and not at the infusion site.

Central intravenous fluid at 65 degrees C is a more rapid means of treating hypothermia than standard 40 degrees C intravenous fluid. It is safe even in hypovolemic animals.