[Regulation of blood oxygen transport function in patients after open-heart surgery].

The oxygen transport function of the blood was studied in 223 patients in the early postoperative period after open-heart surgery, which included correction of acquired cardiac valve defects and aortocoronary bypass. The studied parameters comprised central hemodynamics, pulmonary gas exchange, oxygen supply and utilization, acid-base status, blood gas and lactate content, as well as erythrocytic 2,3-diphosphoglycerate (DPG); Boehringer Mannheim reagents (FRG) were used. The venous blood P50 was calculated using a Severinghaus device. It was found, that the Bohr effect and temperature changes are the major factors controlling the Hb affinity to oxygen. No coefficient modifications in pH and T were detected. Patients with cardiac and pulmonary disorders showed, along with the Bohr effect and temperature influences, an additional shift of the oxyhemoglobin dissociation curve. A positive relationship was revealed between the 2,3-DPG level and standard P50 value. However, the coefficient was low (0.010) at 2,3-DPG and insufficiently stable. It is most probable, that 2,3-DPG mediates the buffer effect eliminating the drastic P50 deviations and is not completely responsible for additional ODC shifts in cardiopulmonary disorders. A quantitative relationship between hypoxia and Hb affinity to oxygen was revealed. The coefficient at SO2 Y varied from -0.0025 to -0.0030 by one percent of changes in the latter. Reduction in SO2 by 15 percent in cardiopulmonary patients was equivalent to the Bohr effect at a pH fall by 0.1 unit.