Preparation and Evaluation of Hemoglobin‐Polyethylene Glycol Conjugate (Pyridoxalated Polyethylene Glycol Hemoglobin) as an Oxygen‐Carrying Resuscitation Fluid

Human hemoglobin was pyridoxalated and subsequently coupled with the activated ester of polyethylene glycol (PEG) to provide an oxygen-carrying resuscitation fluid. The PEG conjugate of pyridoxalated hemoglobin (pyridoxalated PEG hemoglobin) has a longer half-life in the circulation (12.8 h) than does hemoglobin (2.2 h) when the solutions are exchange-transfused by approximately 60%. The P50 of pyridoxalated PEG hemoglobin, which is the partial pressure of oxygen at which one-half of the absorbed oxygen is released, was 21.3 +/- 1.4 mm Hg (mean +/- SD, n = 5) (37 degrees C, pH = 7.4), which is close to that of human whole blood (25.9 +/- 0.6 mm Hg). The colloidal osmotic pressure and the viscosity were 36.5 +/- 2.4 mm Hg (n = 5) and 2.6 +/- 0.4 cp (n = 5), respectively. The results indicate that the pyridoxalated PEG hemoglobin solution has favorable properties for use as an oxygen-carrying resuscitation fluid.