Life-saving effect of pyridoxalated hemoglobin-polyoxyethylene conjugate on carbon monoxide intoxication of rabbits

We examined whether pyridoxalated hemoglobin-polyoxyethylene conjugate (PHP) could be life-relievable for carbon monoxide (CO) intoxication. Toxic gas (O2, 5.0%; CO2, 16.0%; CO, 1.8%; and N2, 77.2%) was inhaled by rabbits anesthetized with urethane and the following parameters were measured: blood pressure, arterial and venous Po2, Pco2, pH, and carboxyhemoglobin (COHb). When mean blood pressure reached 0 or 20 mm Hg as an index after inhalation of the toxic gas, the toxic gas was switched to air; intravenous infusion of physiological saline or PHP (1.2 g/20 ml/kg/30 min) was simultaneously initiated. In the experiment using 0 mm Hg blood pressure, PHP prolonged the survival time and exhibited significant temporary recovery of P02 and Pco2 in comparison with saline. In the experiment using the 20 mm Hg blood pressure, a significant difference in each parameter was observed between the saline and PHP groups. Two of 8 animals in the saline group died without any recovery of each parameter. All 6 animals in the PHP group survived and each parameter recovered. PHP accelerated recovery from high COHb concentrations, low arterial and venous Po2, reduction of arterial and venous Pco2, and elevations of pH and blood pressure. These results suggest that PHP treatment during the early stage of CO intoxication is life-saving and effective in facilitating the recovery of various functions.