Advances in oxygen monitoring of trauma patients.

Monitoring the critically injured patient is imperative, to assure adequate resuscitation from shock. Unfortunately, the commonly monitored variables correlate poorly with ultimate survival. As a result, therapy is inappropriately focused. Invasive monitoring (by way of a pulmonary artery catheter and arterial cannula) permit serial determinations of parameters pertaining to oxygen delivery as well as oxygen consumption. These are crucial in defining the shock state as well as the need for therapeutic intervention. Recent advances in mixed venous oximetry offer alternative means of assessing the adequacy of peripheral delivery of oxygen. With the advent of metabolic carts, it became feasible to measure respiratory gas exchange to determine oxygen consumption. Complexity, expense, and time clearly limit practical application of that technology to a small percentage of patients in the intensive care unit. Unfortunately, unrecognized hypoxemia remains a common problem. Advances in noninvasive monitoring offer alternative means to assess oxygenation. Pulse oximetry and transcutaneous oxygen monitoring are the state of the art. The pertinent devices are easy to use, portable, and accurate. Knowledge of their technical and physiologic limitations is needed to assure reliability. Their potential role extends beyond the intensive care unit setting, such as with prolonged radiologic evaluation or difficult transportation.