Comparison between the use of whole blood versus a diluted perfusate in regional isolated perfusion by continuous monitoring of transcutaneous oxygen tension: a pilot study.
In 12 successive women (median age, 58 [39-89] years) who were treated with regional isolated perfusion for melanoma of the lower extremities, peroperative continuous monitoring of the transcutaneous oxygen tension (PtcO2) was performed as an indicator for tissue oxygenation and (sub)cutaneous perfusion. Regional perfusion started using whole blood as perfusate with a hematocrit of 40.7 +/- 4.9. After 40 min of drug circulation the perfusate was diluted to a hematocrit of 25.3 +/- 4.9, a value usually applied in perfusion. Flow rates (mean 51.2 +/- 14.4 mL/min/L perfused tissue) were kept at a level that caused no systemic leakage and no more than 10-cm increase above starting venous pressure. Oxygen supply was set at one half of the flow of the perfusate (in mL/min). The mean PtcO2 during the first part of perfusion, in which seven patients could achieve preperfusion levels for at least some of the time, was significantly higher than during the last part, in which no patient reached the preperfusion level (30.8 mm Hg vs 23.5 mm Hg; p = .0019). The mean maximal decrease in PtcO2 after dilution was 21.3 +/- 11.6 mm Hg. Venous blood gases of the perfusate also deteriorated after dilution. Two patients encountered a grade III and two a grade IV toxicity reaction after perfusion. We conclude that increasing the hematocrit of the perfusate to physiologic levels by using whole blood can guarantee a physiologic tissue oxygenation at relatively low flow rates. However, physiologic tissue oxygenation on its own is not enough to prevent toxicity after perfusion.