OXYGEN DELIVERY AND OXYGEN-UPTAKE IN POSTOPERATIVE AND SEPTIC PATIENTS

Pathologic dependency of V̇O2 on ḊO2 has been reported in postoperative and septic patients. We studied the influence of an artifact due to calculation of V̇O2 from CO and AV content difference. In 13 postoperative and seven septic patients, the relationships between ḊO2 and cV̇O2 and between ḊO2 and mV̇O2 were analyzed by linear regression. In ten patients, cV̇O2 and ḊO2 were significantly correlated, but in only two of these patients mV̇O2 also correlated with ḊO2. In two patients, there was a significant correlation between mV̇O2 and ḊO2. The main contribution to the correlation and to the slope of the regression line between cV̇O2 and ḊO2 may be due to mathematic coupling of cV̇O2 and ḊO2. With cV̇O2, erroneous conclusions concerning the V̇O2-ḊO2 relationship may be drawn. In four patients, ḊO2 and mV̇O2 were significantly related, reflecting either physiologic coupling or pathologic supply dependency of V̇O2.