[Hemoglobin-oxygen affinity in acute respiratory and circulatory disorders in patients following open heart surgery]

Hemodynamic parameters, lung gas exchange, hemoglobin, acid-base balance, gases, blood lactate and pO2 have been studied in 105 patients with acute cardiorespiratory disturbances (CRD) after open heart surgery. The actual P50 was determined by the venous point, using the Severinghaus blood gas analyser. The method of multidimensional regression analysis was used to study the contribution of some factors determining oxyhemoglobin dissociation curve (ODC) shift. It has been shown that CRD are characterized not only by Bohr's effect and temperature impact but also by ODC shifts, which cannot be accounted for by changes in erythrocyte 2,3-diphosphoglycerate concentration. As hypoxia is universal for any CRD the index of mixed venous blood saturation with O2 (Sv-O2) was considered as a factor determining hypoxic ODC shift and a numerical contribution of hypoxia to P50 changes has been determined. The coefficient in delta Sv-O2 was 0.0025-0.0030 15% Sv-O2 changes were in Bohr's effect equivalent to ODC shift, with pH changing by 0.1. The role of hypoxia in the changes of Hb-O2 affinity in CRD is discussed.