Blood flow changes measured with laser Doppler flowmetry during hyperthermia

Thirty dogs were heated with interstitial RF hyperthermia through four pairs of electrodes placed in the rear leg muscle, 6 cm distal to the femoral head. During one hour of 43 degrees C treatment, perfusion rates increased from the control value of 10 ml/min/100 gm to 39 ml/min/100 gm after 8 minutes of treatment. This initial increase in perfusion, most likely a reactive hyeremia due to the interstitial treatment, decreased back to the control level within minutes. This first peak was followed by a second peak at 40 min of treatment. This second peak reached 46 ml/min/100 gm. Following treatment, perfusion rates were measured in tissue at various times over the next week. At 4 hours following treatment, blood flow dropped to 17 ml/min/100 gm. The blood flow continued to drop over the next 48 hours, reaching 12 ml/min/100 gm. By the end of the week, the blood flow had returned to an average of 19 ml/min/100 gm.<>