EFFECTS OF NORMOVOLEMIC AND HYPERVOLEMIC HEMATOCRIT VARIATIONS ON MUSCLE-TISSUE OXYGEN-PRESSURE IN PATIENTS WITH CHRONIC ISCHEMIA OF THE CALF MUSCLE

It was the aim of the study to characterize the effects of normovolemi c and hypervolemic hemodilution on the muscle pO(2) in the tibialis an terior muscle of patients suffering from chronic arterial occlusive di sease (stage IIb according to the Fontaine classification) with a pain -free walking distance below 100 m. To compare various Hct levels (ran ging from 30% to 50%), normovolemic and hypervolemic hemodilution was performed either by subsequent withdrawal of whole blood and substitut ion with hydroxyethylstarch solution (200/0,5) or only by infusion of the same plasmaexpander. At rest, muscle pO(2) readings obtained by a polarographic method (micro-pt-needle electrodes) indicated clearly an impaired oxygen supply as compared to age-matched elderly volunteers. At the extreme ends of hematocrit in this study (Hct 33.75% and Hct 5 0.60%) muscle pO(2) was significantly decreased as compared to Hct ran ging from 38,57% to 45,38%. After a standardized pedal-ergometric exer cise test a significant increase of muscle pO(2) (2 alpha<0,005) was f ound at Hct 40% - 42%. Comparing normovolemic and hypervolemic hemodil ution, hypervolemia at Hct 40%-42% did not improve muscle pO(2) values after the pedalergometric exercise test. The data indicate, that norm ovolemic hemodilution towards the lower normal range (Hct 40% - 42%) c an indeed improve muscle pO(2) after pedalergometric exercise test in patients with severe intermittent claudication and concomitant increas ed Hct (Hct >45%), whereas hypervolemic hemodilution showed no increas e of muscle pO(2). Thus, normovolemic hemodilution should be the prefe rred hemodilution regimen in patients suffering from intermittent clau dication.