Oxygen Affinity of Erythrocytes and Pulmonary Gas Exchange in Patients on Continuous Ambulatory Peritoneal Dialysis

Abstract

In 11 patients on continuous ambulatory peritoneal dialysis 2,3-diphosphoglycerate, oxygen (O₂) affinity of red cells (P₅₀), blood gases, ventilation, and O₂ consumption were studied. Contrary to patients on maintenance hemodialysis, 2,3-diphosphoglycerate and P₅₀ were normal in patients on continuous ambulatory peritoneal dialysis; they were correlated with each other. Arterial O₂ pressure was normal; under the conditions of dialysis with 35 mmol lactate per liter dialysis fluid a slight metabolic acidosis persisted; it was combined with a moderate respiratory alkalosis. Position had no influence upon pulmonary gas exchange with the exception of the alveolo-arterial gradient which was elevated when the abdominal cavity was filled with dialysis fluid and the patients assumed the supine position. Ventilation was in the normal range, whereas O₂ consumption was low, possibly due to a reduction in muscle mass in some of the patients. It is concluded that pulmonary gas exchange and erythrocyte O₂ transport were normal and that O₂ requirements tended to be low in this group of patients on continuous ambulatory peritoneal dialysis.

Factors That Affect Oxygen Affinity of Hemoglobin in Chronic Hemodialysis Patients

“…The low correlation coeffi cients between P50std and hemoglobin and between P50std and 2,3-DPG in our study are in accord with some reports [5,14], but are contrary to the others [2,15]. The discrepancy seems to be due to the states of acid-base balance of the subjects.…”

“…The discrepancy seems to be due to the states of acid-base balance of the subjects. The patients who were nonacidotic showed good correlation between these parameters [2,15]. On the other hand, those who were acidotic showed poor correlations [5,14], Acidosis influences Hb-0 2 affinity directly (through Bohr's effect) and indirectly (through decreasing 2,3-DPG), thus may complicate the relationship between Hb, 2,3-DPG, and P5(,std.…”