The oxygen delivery/consumption controversy. Approaches to management of the critically ill.

There is no doubt that physiologic dependence of VO2 on DO2 occurs in patients in shock. Whether pathologic dependence of VO2 on DO2 occurs in the critically ill has not yet been conclusively shown, partly because of the problem of mathematical coupling of shared measurement error of cardiac output and arterial oxygen content in many studies. In our opinion, contradicting RCTs of increased DO2 and the problems encountered in the RCTs to date do not support the practice of increasing DO2 to supranormal levels. Finally, we suggest that until technology is available to better assess DO2 and VO2 of vital organs and tissues, the clinician can negotiate this controversial area in individual patients by applying careful clinical assessment and judgement of patient response to changes in DO2.