OPTIMAL HEMATOCRIT IN PATIENTS WITH PERIPHERAL OCCLUSIVE ARTERIAL-DISEASE (POAD) - EXERCISE-INDUCED MUSCLE-TISSUE PO2 AFTER ISOVOLEMIC HEMODILUTION

Isovolumetric hemodilution (IHD) is an established therapeutic procedu re to improve chronic ischemia in patients suffering from intermittend claudication of the lower limbs. It is, however, still subject of dis cussion at which hematocrit the relation between blood flow properties and oxygen carrying capacity of blood is at its optimum in this defin ed ischemic disease. The aim of the present study was to characterize the influence of hematocrit variations on the muscle tissue oxygen sup ply as the defined muscle tissue pO2 in these patients at rest and aft e exercise. Design, Material, and Methods: IHD was performed twice wit hin 14 days in 23 patients (age: 41 - 72yrs) with a painfree walking d istance less than 100 by withdrawl of whole blood and subsequent infus ion of the same amount of a 10% hydroxyethyl starch solution 200/0.5 ( HAES steril 10%, Fesenius, Oberusrsel Germany). Measurements of muscle tissue pO2 in the anterior tibial muscle (micro needle-electrode meth od according to Ehrly and Schroeder) were performed regularly three da ys before and after pedalergometric exercise in parallel to several ot her hemodynamic and hemorheological tests. Results: At rest muscle tis sue pO2 reading revealed an impaired oxygen supply at high (51%) and l ow (34%) hematocrit values whereas an increase was found with hematoci rt levels in ther normal range (approx. 40%). After. excercise, signif icant increase of the muscle tissue pO2 was found exclusively at hemat ocrit levels of 40% - 42%. This increase was accompanied by a ''normal isation'' of the execise induced pattern of ''reactive hypoxia'' as de fined by micro-needle-electrodes. Conclusion: In patients suffering fr om intermittent claudication IHD towards a hematocrit of 40% - 42% res ulted in improvement of muscle tissue oxygen supply and execise condit ions. Further reduction of hematocrit to hematocrit levels below 38% i mpairs muscle tissue oxygenation. Thus, for conservative treatment str ategies, isovolemic hemodilution should be applied regularly and ''opt imal hematocrit'' is the lower boderline of the normal range (40% - 42 %).