OXYGEN DELIVERY AND CONSUMPTION IN HEAD-INJURED AND MULTIPLE TRAUMA PATIENTS

Critically ill patients often demonstrate that whole body oxygen consumption ((Formula Presented)O2) is dependent on oxygen delivery (ḊO2). In this retrospective study, the relationship of (Formula Presented)O2 to ḊO2 in patients with isolated head injury (HI, n = 18) was compared to that in patients with multiple trauma (MT, n = 60) without serious head injury. Mean pulmonary capillary wedge pressure, central venous pressure, arterial PCO2, cardiac index, and oxygen delivery were significantly lower in HI, but oxygen consumption was not different in the groups. In both groups, changes in ḊO2 (ΔḊO2) within each patient were significantly correlated with changes in (Formula Presented)O2 (Δ(Formula Presented)O2) in that same patient. This relationship was not different between the HI patients, (Δ(Formula Presented)O2 = (0.20 ± 0.02) ΔḊO2), and the MT patients (Δ(Formula Presented)O2 = (0.17 ± 0.01) ΔḊO2). When these groups were further divided into those with high hematocrit (>32%) and low hematocrit (<32%), HI patients with a low hematocrit demonstrated a steeper regression slope, with 26 ± 3% of the ḊO2 change being reflected in the (Formula Presented)O2 change. This was significantly greater than the slope in HI patients with high hematocrit (13 ± 3%) and the MT patients at high (19 ± 2%) or low (16 ± 2%) hematocrits. These data show a correlation between changes in oxygen delivery and consumption that is similar in both head-injury patients and multiple trauma patients without serious head injury. This relationship was greatest in head-injured patients at low hematocrit. This relationship of V02 and D02 in both groups suggests an influence of neurohumoral factors rather than local tissue phenomena. It also suggests that particular attention be directed towards maintaining and optimizing oxygen delivery in both groups of these severely injured patients. © 1990 by The Williams and Wilkins Co.