CHANGES IN MUSCLE BLOOD-FLOW DISTRIBUTION DURING HYPERTHERMIA

Blood flow is a critical parameter for obtaining satisfactory temperat ure distributions during clinical hyperthermia. This study examines th e changes in blood flow distribution in normal porcine skeletal muscle before, during and after a period of regional microwave hyperthermia. The baseline blood flow distribution during general anaesthesia and a fter the insertion of the thermal probes was established independently in order to isolate the changes due to hyperthermia. General anaesthe sia alone and thermocouple insertion during anesthesia had no signific ant effect on the muscle blood flow distribution. Regional microwave h eating generated a non-uniform blood flow distribution which was a fun ction of the tissue temperature distribution. Blood flow was greater i n those tissues samples in which higher temperatures were recorded and less in those sampled further from the applicators peak SAR (Specific Absorption Rate). The increase in blood flow appears to be primarily a local phenomenon. Although muscle blood flow may be considered to be uniform prior to heating, this does not hold during hyperthermia trea tment. Therefore, the non-uniform nature of the brood distribution dur ing heating should be incorporated into any practical bioheat transfer model.