Heat turn-over during hyperthermic peritoneal perfusion. An experimental study.

In order to study heat turnover, 3 experimental models of chemotherapeutic hyperthermic intraperitoneal perfusion (CHIP) were tested, using 15 rabbits divided into 3 separate groups of 5 animals each. A normal saline perfusate, containing a standard concentration of 10 mg of methotrexate per liter, was recycled through the peritoneal cavity, transmitting, in every group, 6,000 calories of heat. In model I, heat transmission was achieved by a high temperature gradient, in model II by the increased thermocapacity of a great priming volume of perfusate, using a peritoneal expander, and in model III by a high flow rate. The rectal and oesophageal temperatures were recorded and the indications converted to calories. The bowel showed a statistically higher heat uptake in model III, whereas thermodilution was more important in model I and especially in model II. The results indicated that the ideal model of CHIP must combine efficiency and safety. The temperature gradient must be ample, but within safe limits, only for cost-efficiency reasons. The priming volume ought to be abundant enough to achieve homogeneity and constancy of heating, but not excessive, in order to avoid abdominal distension and bodily thermo-dilution. Under these conditions, the target level of heating, always calculated in calories, must be administered by appropriate adjustment of the perfusion flow rate.