Blood oxygen tension and oxyhemoglobin saturation in hypoxemia due to right to left shunt or low inspired oxygen concentration. An experimental study of the effects of changes in blood oxygen affinity.
Oxygen tension, oxyhemoglobin saturation, and pH were measured in arterial and in venous blood from heart, brain, kidney, liver, gut and pulmonary artery in anesthetized hypoxemic dogs during a reduction of blood oxygen affinity due to increasing acidosis caused by the administration of CO2 and NH4Cl (pH range 7.40-6.80). In dogs with hypoxemia due to right to left shunt (anastomosis between inferior vena cava and left atrium), a reduction in blood oxygen affinity was followed by increasing Pao2 and Pvo2 at unchanged Sao2. In dogs with hypoxemia caused by alveolar hypoxia, or a combination of alveolar hypoxia and right to left shunt, a reduction of blood oxygen affinity was followed by arterial and venous desaturation at unchanged Pao2 values. Infusions of sodium bicarbonate or blood transfusions with reduced 2,3-diphosphoglycerate (2,3-DPG)-concentrations, if given to patients suffering from hypoxemia due to right to left shunt, may reduce the Pao2. Such therapy should be prescribed with caution.
D000138:Acidosis / Q000150:complications; D000328:Adult; D000818:Animals; D004285:Dogs; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007035:Hypothermia / Q000097:blood* / Q000209:etiology; D007231:Infant, Newborn; D008297:Male; D010100:Oxygen / Q000097:blood*; D010108:Oxyhemoglobins / Q000032:analysis*; D010313:Partial Pressure; D011650:Pulmonary Alveoli / Q000378:metabolism
D010108:Oxyhemoglobins; D010100:Oxygen