Previous studies have described oxygen delivery (DO2) and oxygen consumption (VO2) relationships in patients with ARDS and other acute diseases that suggest occasions when VO2 may be dependent on the supply of oxygen, ie, DO2. We studied 127 postoperative patients who developed ARDS to evaluate the relationship of DO2 to VO2. We found a weak correlation between DO2 and VO2 in the total series (r = 0.49) as well as in several clinical subgroups of patients with ARDS. Moreover, we observed similar relationships in a concurrent group of 218 postoperative patients who did not develop ARDS. We also examined the DO2/VO2 data of individual patients with ARDS to identify instances where flow-dependent VO2 patterns developed into flow-independent VO2 patterns. We were able to identify an apparent plateau in the DO2/VO2 relationships in 29/50 (58 percent) patients where multiple measurements were obtained over a short period of time. Our data are consistent with the concept that the DO2/VO2 relationship in acutely ill early postoperative patients with and without ARDS is affected by antecedent circulatory problems that may lead to tissue hypoxia and tissue oxygen deficiencies that are manifest by flow dependency.