Transcranial Doppler sonography mean flow velocity during infusion of ultrapurified bovine hemoglobin.

A number of studies have shown that polymerized bovine hemoglobin (HBOC-201) does not cause clinically significant side effects. This has been demonstrated in spite of the fact that a primary increase in oxygen extraction ratio has been associated with an increase in systemic vascular resistance (SVR) and a decrease in cardiac index (CI). The current study investigated the effects of HBOC-201 on cerebral circulation. Middle cerebral artery mean flow velocity (Vm) was measured using Transcranial Doppler sonography. After institutional review board approval and informed consent were obtained, 12 patients (mean age 59+/-10 years), scheduled for hepatic resection, were enrolled. Anesthesia during the induction period consisted of etomidate (0.3 mg/kg), fentanyl (3 mcg/kg), and vecuronium (0.1 mg/kg). Anesthesia during the maintenance period consisted of isoflurane (0.64-0.8 vol%)/O2/N2O (FiO2=0.3), fentanyl, and vecuronium. End-tidal carbon dioxide partial pressure (PetCO2), arterial carbon dioxide partial pressure (PaCO2), mean arterial blood pressure (MAP), CI, SVR, mean flow velocity, and pulsatility index were measured in each patient. Hemodilution was performed in all patients, followed by randomized assignment to two groups: Group 1 (n=6) received 0.4 g/kg HBOC-201, Group 2 (n=6) received a corresponding volume of hydroxyethyl starch (mw 70,000). Measurements were taken at six points (PMs): before hemodilution (PM 1); following hemodilution (PM2); and at 3, 10, 20, and 30 minutes (PM 3-6) after infusion of HBOC-201 or starch. Systemic vascular resistance rose in Group 1 as compared with Group 2, with significant differences at PM 3-6. The greatest difference was at PM 6 (Group 2=1071 dyne x s x cm(-5); Group 1=2154 dyne x s x cm(-5)). Cardiac indices were significantly lower in Group 1 (1.7-1.8 l/minute x m(-2)) than in Group 2 (2.4-2.7 l/minute x m(-2)) after PM 3. After hemodilution, mean flow velocity showed an insignificant increase in both groups, ranging from 39 to 46 cm/second. Although SVR increased significantly following HBOC-201 -infusion, the results of this study did not reveal changes in cerebral blood flow that establish significant group-to-group differences.