BOVINE HEMOGLOBIN PRESERVES TISSUE OXYGEN -TENSION IN POSTSTENOTIC SKELETAL-MUSCLE

We investigated the effects of ultrapurified polymerized bovine hemogl obin (HBOC-201) on skeletal muscle tissue oxygen tension when applied before establishment of a nearly complete arterial stenosis. Methods: Twelve foxhounds were anaesthetized IV and mechanically ventilated wit h 30% oxygen in air. Catheters were inserted into the right femoral ar tery and vein for measurements of haemodynamic parameters and blood-ga s sampling. Arterial blood flow of the left popliteal artery was measu red by an electromagnetic flow probe. Skeletal muscle tissue oxygen te nsion (tpo(2)) was measured in the left gastrocnemic muscle using a st epwise-driven polarographic needle probe, creating histograms from 200 single tpO(2) measurements. Following isovolaemic haemodilution with Ringer's solution to a target haematocrit of 20%, the animals were ran domly assigned to receive either 200 ml of predonated fresh blood (gro up 1) or 200 ml of HBOC-201 (MW 32000-500000; Hb 13+/-1 g . dl(-1); gr oup 2). After a 15-min stabilization period, a 95% artificial stenosis of the left popliteal artery was established. While animals of group 1 received two applications of 200 ml 6% hetastarch (HES, 200000; 0.5) , animals of group 2 received 200 mi Ringer's solution 45 and 75 min a fter establishment of the arterial stenosis, respectively. Variables w ere measured at baseline, after haemodilution and application of the r espective compound, and 30, 60 and 90 min after establishment of the s tenosis. Results: Demographic data, muscle temperature and arterial bl ood gases did not differ between groups. With the exception of a highe r mean pulmonary artery pressure in HBOC-201-treated animals, haemodyn amics did not differ between groups. In both groups oxygen delivery an d oxygen consumption of the muscle decreased in parallel to the decrea sing blood flow during arterial stenosis. In contrast, oxygen extracti on ratio increased after infusion of HBOC-201 and remained unchanged d uring stenosis (P<0.05). In group 1, the tpO(2) decreased during steno sis when compared to baseline (P<0.001) and remained decreased after a dministration of HES. In contrast, administration of 200 ml of HBOC-20 1 before establishment of the arterial stenosis sustained the tpO(2) v alues at nearly baseline levels during stenosis. Skeletal muscle tissu e oxygen tension was higher after HBOC-201 infusion during stenosis wh en compared to HES infusion (P<0.001). Conclusion: These data suggest that haemoglobin solutions can reach poststenotic tissues. The increas ed oxygen extraction after application of HBOC-201 is associated with improved skeletal muscle oxygen tension during severe arterial stenosi s.