Enhanced O 2 Transportation During Cardiopulmonary Bypass in Piglets by the use of Inositol Hexaphosphate Loaded Red Blood Cells

A continuous lysing and resealing of erythrocytes permitted internalization of inositol hexaphosphate (IHP), a strong allosteric effector of Hb, leading to significant rightward shifts of the HbO₂ dissociation curve. Twelve piglets were put on cardiopulmonary bypass (CPB) with the heart beating, cooled to 25° C then rewarmed to 37° C before weaning off CPB. AoP, LV pressure, PAP, and cardiac output (CO) were monitored. Blood samples were taken before CPB, at 25° C, at 30° C, at 37° C and after CPB for assessment of blood gases, arterio-venous difference in O₂ content, lactates, P₅₀ (partial pressure of O₂ at 50% Hb saturation), and ionogram. Control group I included five pigs where the CPB circuit was primed with Ringer's lactate solution and porcine blood. In group II (n=5), priming was done with Ringer's lactate solution and IHP loaded erythrocytes. P₅₀ was significantly higher during CPB than before surgery in group II (20%), but not in group I (1%). There was a significant increase in VO2 in group II (6.02 ml/min) compared to group I (4.03 ml/min) (p < 0.05) after CPB. Hemodynamics improved after CPB in group II (mean AoP 42 mmHg and syst LVP 70 mmHg) compared to group I (AoP 25 mmHg and syst LVP 22.5 mmHg). These preliminary results show that O₂ transportation at the end of CPB is enhanced and myocardial function is improved in piglets with the use of IHP erythrocytes.