Effects of normovolemic and hypervolemic hematocrit variations on muscle tissue oxygen pressure in patients with chronic ischemia of the calf muscle

Abstract

It was the aim of the study to characterize the effects of normovolemic and hypervolemic hemodilution on the muscle p02 in the tibialis anterior muscle of patients suffering from chronic arterial occlusive disease (stage lIb according to the Fontaine classification) with a pain-free walking distance below 100 m. To compare various Hct levels (ranging from 30% to 50%), normovolemic and hypervolemic hemodilution was performed either by subsequent withdrawal of whole blood and substitution with hydroxyethylstarch solution (200/0,5) or only by infusion of the same plasmaexpander. At rest, muscle p02 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 50.60%) muscle p02 was significantly decreased as compared to Hct ranging from 38,57% to 45,38%. After a standardized pedal-ergometric exercise test a significant increase of muscle p02 (2a 45%), whereas hypervolemic hemodilution showed no increase of muscle p02. Thus, normovolemic hemodilution should be the preferred hemodilution regimen in patients suffering from intermittent claudication.