Venovenous perfusion-induced systemic hyperthermia: Hemodynamics, blood flow, and thermal gradients

Background. Thermal events during extracorporeal venovenous perfusion-induc ed systemic hyperthermia (VV-PISH) were studied and related to determinatio n of whole-body and regional thermal isoeffect doses. Methods. Swine (n = 6, 77 +/- 4.5 kg) were heated to a target temperature o f 43 degrees C for 120 minutes using VV-PISH. Colored microspheres were inj ected during preheat, heat induction, maintenance, cool down, and after dec annulation. The esophageal, tympanic, rectal, pulmonary artery, bladder, bo ne marrow, kidney, brain, blood, lung, and airway temperatures were recorde d continuously. The thermal dose, thermal exchange, metabolic heat producti on, heat loss to the environment, the change in body heat, and the thermal isoeffect dose were studied at 15-minute intervals. Results. W-PISH increased heart rate and cardiac output and caused a redist ribution of blood flow favoring the thoracoabdominal organs. Greatest therm al exchange occurred during the heating phase (total 2,162 +/- 143 kJ), met abolic heat production contributed in all phases (274 +/- 9 kJ), the greate st change in body heat occurred during heating (1,310 +/- 309 kJ) with a to tal delivered thermal dose of 298 +/- 21 kJ, and the total whole body therm al isoeffect dose at 100 +/- 5 minutes. Conclusions. W-PISH is feasible, is capable of transferring sufficient heat , causes a redistribution of blood flow favoring the thoracoabdominal organ s, and facilitates calculation of whole-body and regional thermal isoeffect doses. (C) 2000 by The Society of Thoracic Surgeons.