Hemodynamics and Oxygen Transport after Partial and Total Blood Exchange with Pyridoxalated Polyhemoglobin in Dogs

The effects of a pyridoxalated polyhemoglobin solution (SFH-PLP)n-solution) on cardiovascular hemodynamics and oxygen transport were investigated in a model of partial and total blood exchange in seven dogs. Cardiac output, mean arterial pressure and heart rate were essentially unchanged, even after total blood exchange, due to the long plasma half-disappearance time of (SFH-PLP)n (36 h) and due to the addition of albumin to the solution. The oxygen-binding capacity of (SFH-PLP)n was 1.1 to 1.2 ml O2/g hb. Oxygen availability was reduced to about 50%, resulting from the low hemoglobin concentration and the decreased oxygen-binding capacity of (SFH-PLP)n. Since cardiac output did not increase, O2-consumption was maintained by an increase in O2-extraction from 21 to about 50%. However the decrease in mixed venous PO2 to values not below 30 mmHg (4.00 kPa) proves the sufficient unloading capacity of (SFH-PLP)n. The adequate tissue oxygenation of (SFH-PLP)n could be demonstrated by the lack of a metabolic acidosis, the essentially unchanged PO2-histograms of the skeletal muscle and the only moderate decrease in mixed venous PO2. Four dogs survived for more than 3 days; three of them were long-term survivors. This suggests that oxygen supply was maintained by (SFH-PLP)n until red blood cells were restored.