Effects of age and obesity on hemodynamics, tissue oxygenation, and outcome after trauma

Objectives: The aims of this study are (1) to describe the early time course of hemodynamic and tissue perfusion/oxygenation patterns in the elderly and in obese patients who survive and those who die after trauma; and (2) to evaluate postinjury hemodynamic patterns for use as guides for resuscitation and subsequent treatment. Methods: we noninvasively monitored 625 trauma patients upon arrival in the emergency department to assess the temporal hemodynamic patterns associated with age and obesity. Cardiac index (CI), mean arterial pressure, and heart rate were monitored to assess cardiac function, pulse oximetry (Sapo(2)) to reflect changes in pulmonary function and transcutaneous oxygen (PtcO(2))1 carbon dioxide (PtcCO(2)), and oxygen delivery (DO2) to reflect tissue perfusion. We evaluated these hemodynamic data after they were stratified by the patient age and body mass index. Results: When all trauma patients were considered together, the predominant findings were high CI, transient hypotension, tachycardia, normal pulmonary function, and reduced tissue oxygenation. The elderly and, to a lesser extent the obese, had lower flow and tissue perfusion. The survivors had higher CI and better tissue oxygenation than did the nonsurvivors of each category. Conclusions: Elderly and obese nonsurvivors of severe injury had low CI with reduced tissue oxygenation associated with organ failures and death. The study suggests that survivors' CIs and tissue oxygenation may be used as markers of circulatory deterioration and shock as well as resuscitation.