Stress Response to Surgery and Trauma

The body responds to trauma or surgical stress in a characteristic fashion ( Fig. 77-9 ). Monitoring of the stressed surgical or trauma patient has demonstrated a pattern of physiologic adaptations designed to return the host to normal function.^{[12] [13]} The pattern reflects the adequacy of the host defense system and arises out of the interorgan fuel metabolism and immunologic response mechanisms. The normal stress response is characterized by a neurohormonal sympathetic response mediated by a rise in norepinephrine, epinephrine, glucagon, and cortisol levels. Hemodynamically, heart rate, contractility, and cardiac index increase. Oxygen consumption is augmented. Metabolically, in the first few days after trauma injury, the normal balance between anabolic and catabolic processes is altered in the direction of catabolic metabolism. The catabolic response is mediated primarily by a rise in the catabolic hormones. Glucose turnover increases at least twofold. The rate of glucose production can be matched by an increased rate of use such that euglycemia is maintained. Within days, this sympathetic stress response abates, and lean muscle mass is restored. This

Figure 77-9 Interorgan substrate fluxes in response to trauma or surgery.