INDUCTION OF WHOLE-BODY HYPERTHEMIA WITH VENOVENOUS PERFUSION

Whole body hyperthermia can be used for the treatment of metastatic ca ncer and human immunodeficiency virus infections, The therapeutic effe cts of hyperthermia are dependent upon the actual temperature of the t arget tissues. Therefore, homogeneous distribution of heat and precise control of temperature gradients is critical. To describe heat distri bution during hyperthermia induced by venovenous perfusion, the author s used multiple channel temperature monitoring and a servo-regulated p erfusion/heat exchange system. Young swine were randomly assigned to e ither a heated group (perfusion-induced hyperthermia, target core temp erature at 43 degrees C, n = 6) or a control group (perfusion alone, t arget core temperature at 38 degrees C, n = 6). Blood was drained from the external jugular vein, heated with a computer assisted heat excha nge system, and reinfused through the femoral vein at a flow of 10 ml/ kg(-1)/min(-1). Temperature probes in the esophagus, right and left ty mpanic canals, brain, pulmonary artery, arterial and venous blood, rec tus spinae muscle, kidney, rectum, bone marrow, bladder, subcutaneous tissue, gluteus, and skin were simultaneously recorded. During the hea t induction phase, the maximum water temperature was 54 degrees C, wit h a heating gradient of the blood (blood in - blood out) at 6 degrees C. The maximum temperature difference between tissues was 3.6 degrees C (kidney and esophagus) during heat induction, but decreased to 1.75 degrees C during maintenance. Bone marrow temperature was consistently 1-2 degrees C below the average core temperature of 43 degrees C thro ughout the experiment, The authors conclude that venovenous perfusion can predictably induce hyperthermia, but is associated with heterogeno us temperature distribution among organs. Further studies are necessar y to evaluate different perfusion and heating patterns to achieve homo genous hyperthermia.