Feasibility and analysis of thermal parameters for the whole-body-hyperthermia system IRATHERM-2000

The infrared system IRATHERM-2000, with water-filtered infrared A wavelengt h underwent 20 treatments of whole body hyperthermia in conjunction with ch emotherapy. In all the sessions, the aimed systemic temperature (41.8 degre es C, maximum 42.0 degrees C) could be achieved and maintained for 60 min. Due to increasing clinical experience, the unnegligible local toxicity, exh ibited as heat-induced superficial lesions, and neurotoxicity, could be red uced during the course of the study. Data from three other series accomplis hed at the von Ardenne Clinic, totalling 120 heat sessions, were available and included for a comparative analysis. Analysis of the toxicity shows tha t a correlation exists between thermal side-effects and heat-up periods (un til steady-state), maximum temperatures, and superficial thermal doses. The time needed to reach the plateau seems to correlate with fluid loss, which , thus, indirectly influences toxicity, and most importantly the initial po wer level. The typical heat-up time in such a standard set-up amounts to 10 0-150 min, for a temperature rise from 37.5 to 42.0 degrees C. Evaluation o f the energy balance reveals a highly patient-specific range for the reacti ve evaporation in the IRATHERM system, resulting in a power (heat) loss of up to 1400 W via sweat production of similar to 2 l/h. In order to counterb alance this effect, an accordingly high infrared power, ranging from 1200-1 500 W, needs to be delivered, resulting in a significant thermal skin expos ition. Concepts used to reduce the heat loss by reactive evaporation includ e prevention of convection by appropriate sealing of the heating chamber an d increasing the humidity by a nebulizer. For the more trained user, the he at-up time can be considerably shortened, particularly, in the introductory phase of the heating process, by employing higher, but still tolerable, pa tient-specific power levels. However, such a strategy requires, due to high er risks, close monitoring of skin temperatures together with a considerabl e amount of clinical experience. The results of the IRATHERM pilot study we re compared, not only with previous groups where the IRATHERM was applied, but also with results of various other investigators where the Enthermics R adiant Heat Device was employed. In the authors' opinion, improved understa nding of the mechanisms and crucial parameters underlying whole body hypert hermia, will enable a controllable and tolerable therapy through proficient contribution to equipment and methods.