PHYSIOLOGICAL IMPLICATIONS OF HYPERBARIC-OXYGEN TENSIONS IN ISOLATED LIMB PERFUSION USING MELPHALAN - A PILOT-STUDY

Controversy exists concerning the optimal pO(2) of the perfusate durin g isolated limb perfusion (ILP) with melphalan. Therefore we studied t he implications of hyperbaric oxygen tensions in the perfusate. In 12 consecutive patients, subcutaneous pO(2) (Continucath 1000(R)), tissue and tumor pH, and blood gas values were monitored throughout the ILP procedure. ILP started with an oxygen flow through the bubble oxygenat or which was set routinely at one half of the flow of the perfusate; 3 0 min before the end of ILP, the oxygen flow was tripled. Mean arteria l pO(2) before and during ILP (before and after increasing the oxygen supply) was 19.4, 25.5 and 49.4 kPa, respectively. Mean subcutaneous p O(2) values before, during (before and after increasing the oxygen sup ply), and post-ILP, were 7.4, 10.1, 16.3, and 9.1 kPa, respectively. T issue pH values in the subcutis and muscle decreased during routine ox ygen supply (p = 0.001); muscle pH moved towards starting values after increase of the oxygen supply (p = 0.011). In 4 patients, tumor pH wa s recorded showing a rise after increasing the oxygen supply (from 7.1 0 to 7.22; p = 0.11). In conclusion, high pO(2) in the perfusate impro ves muscle pH during ILP. However, a concomitant rise in tumor pH may unfavorably influence the therapeutic effect of ILP, as it has been sh own that low pH increases the cytotoxicity of melphalan.