BLOOD-OXYGEN PARAMETERS IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE - AN EVALUATION OF MEASURED AND CALCULATED 2,3-DIPHOSPHOGLYCERATE CONCENTRATIONS

48 simultaneous arterial and venous blood samples from 15 patients with chronic obstructive pulmonary disease (COPD) were evaluated for calculated p50 and measured and calculated 2,3-diphosphoglycerate (DPG) concentration. 23 samples (48 %) demonstrated a leftward shift in the calculated in vivo p50, whereas both measured and calculated DPG showed 5 % below and 28 % above reference range. Measured DPG was significantly higher than calculated DPG in the leftshifted group, whereas there was no significant difference in the non-leftshifted group. Mean arterial pH was alkalotic in the leftshifted group and significantly higher than mean pH in the non-leftshifted group. It is concluded that DPG concentration cannot be calculated by the algorithm in patients with COPD and a leftward shift in the oxygen dissociation curve.