THE EFFECTS OF INCREASED DOSES OF BOVINE HEMOGLOBIN ON HEMODYNAMICS AND OXYGEN-TRANSPORT IN PATIENTS UNDERGOING PREOPERATIVE HEMODILUTION FOR ELECTIVE ABDOMINAL AORTIC-SURGERY

In two consecutive studies (Study A and Study B), we evaluated the eff ects of increasing doses of HBOC-201, a bovine hemoglobin-based oxygen carrier, on hemodynamics and oxygen transport in patients undergoing preoperative hemodilution for elective abdominal aortic surgery. After the induction of anesthesia and the exchange of 1 L of blood for 1 L of lactated Ringer's solution, 24 patients (12 in each study) were ran domly assigned to receive, within 30 min, a predetermined volume of ei ther HBOC-201 or 6% hydroxyethyl starch (Study A 6.9 mL/kg; Study B 9. 2 mL/kg). Monitored variables included systemic and pulmonary arterial pressures, arterial and mixed venous blood gases, and calculations of cardiac index (CI), systemic (SVRI) and pulmonary (PVRI) vascular res istance indices, oxygen delivery index (Do(2)I), oxygen consumption in dex (Vo(2)I), and oxygen extraction ratio (O2ER). In both studies, the infusion of HBOC-201 was associated with increases in SVRI (Study A 1 21%; Study B 71%) and PVRI (Study A 70%; Study B 53%) and with a decre ase in CI (29% both studies). Hemodilution with HBOC-201 maintained th e arterial oxygen content at levels higher than hemodilution with hydr oxyethyl starch, but the advantage of a greater oxygen-carrying capaci ty was offset by the increase in SVRI, with a resulting net decrease i n both CI and Do(2)I (Study A 30%; Study B 28%); Vo(2)I was maintained by increased O2ER. In terms of hemodynamics and oxygen transport, hem odilution with bovine hemoglobin in these doses provided no apparent b enefit over hemodilution with hydroxyethyl starch. Implications: Bovin e hemoglobin in doses ranging between 55 and 97 g of hemoglobin increa sed vascular resistance and decreased cardiac output in anesthetized s urgical patients. In terms of hemodynamics and oxygen transport, hemod ilution with bovine hemoglobin in these doses provided no apparent ben efit over hemodilution with hydroxyethyl starch.