[Dependence of O2 uptake on O2 transport--a myth or reality?]

According to the concept of supply dependence of oxygen uptake, an improvement of tissue oxygenation in critically ill patients may be obtained by an increase in systemic oxygen transport. A critical review of available clinical data suggests that a positive correlation between calculated oxygen uptake and oxygen delivery does not necessarily imply a 'pathological' dependence of both parameters. Possible pitfalls in the interpretation of results, like mathematical coupling of data, alterations in oxygen demand due to variations in sedation and the calorigenic effect of catecholamines, are discussed.