Oxygen delivery and oxygen uptake in postoperative and septic patients.

Pathologic dependency of VO2 on DO2 has been reported in postoperative and septic patients. We studied the influence of an artifact due to calculation of VO2 from CO and AV content difference. In 13 postoperative and seven septic patients, the relationships between DO2 and cVO2 and between DO2 and mVO2 were analyzed by linear regression. In ten patients, cVO2 and DO2 were significantly correlated, but in only two of these patients mVO2 also correlated with DO2. In two patients, there was a significant correlation between mVO2 and DO2. The main contribution to the correlation and to the slope of the regression line between cVO2 and DO2 may be due to mathematic coupling of cVO2 and DO2. With cVO2, erroneous conclusions concerning the VO2-DO2 relationship may be drawn. In four patients, DO2 and mVO2 were significantly related, reflecting either physiologic coupling or pathologic supply dependency of VO2.