Whole-body hyperthermia: a review of theory, design and application.

The intentional induction of elevated body temperature to treat malignant lesions has its origins in the 18th century. The mechanism of heat-induced cell death is not clear; however, heat induces a variety of cellular changes. For heat to exert a therapeutic effect, pathogens (bacteria, viruses, or neoplastic tissues) need to be susceptible within temperature ranges that do not exert deleterious effects on normal tissues. Hyperthermia has been used successfully to treat isolated neoplastic lesions of the head and neck, regional tumors such as melanoma of the limb, and is under investigation as either an adjunct to, or therapy for, locally disseminated and systemic diseases. The clinical utility of perfusion hyperthermia has evolved into three approaches - isolated organ or limb, tumorous invasion of a cavity, and systemic or metastatic spread. When whole-body hyperthermic treatment has been tried, it has been induced in the patient by submersion in hot wax or liquid, wrapping in plastic, encasement in a high-flow water perfusion suit, or by extracorporeal perfusion. Our group has developed an extracorporeal method, veno-venous perfusion-induced systemic hyperthermia, that was used first to safely heat swine homogenously to an average body temperature of 43 degrees C for 2 h. More recently, a Phase I clinical trial has been completed in which all patients were safely heated to 42 or 42.5 degrees C for 2 h and survived the 30-day study period. We have been sufficiently encouraged by these results and are continuing to develop this technology.

Leukocyte filtration in lung transplantation.

Controlled reperfusion of the transplanted lung has been used in nine consecutive patients to decrease manifestations of lung reperfusion injury. An extracorporeal circuit containing a roller pump, heat exchanger and leukodepleting filter is primed with substrate-enhanced reperfusion solution mixed with approximately 2000 ml of the patient's blood. This solution is slowly recirculated to remove leukocytes prior to reperfusion. When the pulmonary anastomoses are completed, the pulmonary artery is cannulated through the untied anastomosis using a catheter containing a pressure lumen for measurement of infusion pressure. An atrial clamp is left in place on the patient's native atrial cuff to decrease the risk of systemic air embolism during the brief period of reperfusion from the extracorporeal reservoir. During reperfusion, the water bath to the heat exchanger is kept at 35 degrees C and the flow rate for reperfusion solution is between 150 and 200 m/min, keeping the pulmonary artery pressure <14 mmHg. Eight of nine patients were ventilated on 40% inspired oxygen within a few hours of operation and 7/9 were extubated on or before postoperative day 1. Six of nine patients are long-term survivors.