Through a glass darkly: the lung as a window to monitor oxygen consumption, energy metabolism, and severity of critical illness

Abstract

Medical diagnosis and therapeutic monitoring for critical illness require adaptation of laboratory analyses to the bedside. These are greatly helped by the modification of physiological and biochemical data-acquisition techniques to increase the number and accuracy of noninvasive variables that can be obtained from the patient. This paper addresses the choice of noninvasive measurements and is largely directed at the assessment of oxygen debt as a measure of the severity of ischemic and septic metabolic processes. Especially considered are those noninvasive measures of cardiorespiratory adequacy, key variables that need to be considered together with the metabolic function to adequately reflect the patient's state of accommodation to critical illness or injury. I describe a noninvasive sensor system linked to a computer work-station that functions in a pattern recognition mode to permit classification of patients as to the type and severity of their physiological adaptation. This system can serve as a sophisticated bedside monitor of the severity of the patient's condition, as a guide to therapy.