The hemodynamic effects of cell-free hemoglobin during general and epidural anesthesia

Although hemoglobin-based oxygen carriers (HBOC) are now being investigated , the effects of HBOC solutions during regional anesthesia have never been analyzed. Therefore, we investigated the hemodynamic changes after HBOC inf usion during general anesthesia and thoracic epidural anesthesia. Sheep wer e assigned to three different groups: a) a control group with six unanesthe tized sheep; b) six sheep with a halothane anesthesia (2.0 vol. % in oxygen ); and c) six awake sheep with a thoracic epidural anesthesia with bupivaca ine. After a period of stabilization, all 18 animals received 100 mg/kg of the HBOC pyridoxalated hemoglobin polyoxyethylene conjugate. The infusion o f the HBOC caused a significant increase in mean arterial pressure and pulm onary artery pressure in both the control and epidural anesthesia groups. A nesthesia with halothane reduced the effects of the HBOC-solution on mean a rterial pressure but did not abolish the increase in pulmonary artery press ure. Our results demonstrate that vasoconstriction caused by HBOC solutions is not abolished by epidural anesthesia, but halothane anesthesia may alte r the hemodynamic effects of HBOC solutions. Implications: We evaluated the effects of epidural anesthesia and halothane anesthesia on the vasoconstri ctive properties of a cell-free hemoglobin solution. The vasoconstriction c aused by a cell-free hemoglobin solution was similar in unanesthetized shee p and sheep with thoracic epidural anesthesia and was reduced in sheep with halothane anesthesia.