Metabolic Assessment of Tissue Oxygenation

Abstract

From the early days of critical care medicine, physiological monitoring techniques have been introduced in the intensive care unit (ICU) to help clinicians recognize hypoperfusion and tissue hypoxia. As a broad generalization, these monitoring techniques have three characteristics in common: They are complex, expensive, and invasive. None of these physiological monitoring techniques is more ubiquitous or controversial than the pulmonary artery (PA) catheter, a device originally developed to monitor central pressures but whose use was extended to measure cardiac output, systemic oxygen transport, and O₂ consumption. Although the PA catheter has provided much insight into the physiology of pulmonary oxygenation in critically ill patients, it is questionable whether this information is relevant to the assessment of peripheral tissue oxygenation. Clinical experience with measures of systemic O₂ delivery and consumption catheter has demonstrated that systemic measures of oxygenation are insensitive markers of cellular hypoxia. Moreover, there is growing evidence that the PA catheter itself may be an independent risk of mortality in many patients.

Key Words:

Metabolism - oxygen transport - hypoxia