Oxygen uptake/oxygen supply dependency: Fact or fiction?

Abstract

More than a decade ago, observations of co‐variance between VO₂ and DO₂ led to the identification of a condition known as pathological O₂ supply dependency. This condition was subsequently observed in critically ill patients with sepsis and acute circulatory failure. More recently, other authors have challenged the existence of this condition, often citing methodological problems or mathematical coupling to account for spurious observations in the earlier studies. Here, we review the evidence for and against pathological O₂ supply dependency. We find that many of the arguments have some validity but only in specific circumstances. We conclude, therefore, that pathological O₂ supply dependency is a hallmark of acute circulatory failure and that an effective therapeutic approach should be based on an evaluation of organ system function in each individual case. Parameters such as blood lactate, pHi and veno‐arterial Pco₂ may be useful in this respect.