Principles and Practice of Nutritional Support for Surgical Patients

Abstract

The idea of acute care surgery conjures up visions of a spectrum of patients with diverse problems that cross many specialties. However, prolonged starvation or malnutrition worsens the outcome of all patients regardless of their diseases, and the development of acute malnutrition is especially common in the critically ill. Consequently, optimal nutritional support has become a key therapeutic aim in trauma patients and patients requiring acute care surgery. Recognition of the importance of nutritional therapy has led to a search for improved methods of nutritional support that promote wound healing and optimize host immune defenses. Unfortunately, impaired wound healing resulting in anastamotic leaks and wound-related problems as well as the development of septic complications and multiple organ failure still occurs.Nonetheless, one potential way of reducing wound failure, muscle wasting, and sepsis-related morbidity and mortality is by limiting or preventing the adverse consequences of uncontrolled inflammatory-mediated hypermetabolism. Although immune and inflammatory dysfunction in these patients are multifactorial, the nutritional status of the patient clearly plays a major role in the ability to ward off an infectious challenge, and recent evidence suggests that the immune and inflammatory systems can be modulated by the use of specific means of nutritional support. Thus, this chapter focuses on nutritional support for the high-risk patient and emphasizes evidenced-based practice management (Figure 7.1). Metabolism, Nutrition, and InfectionUnderstanding the basic biology of the metabolic response to injury and surgery as well as the role of nutrition in modulating this response is important, because the metabolic status of the patient influences muscle strength, various aspects of host defense against invading organisms, and wound healing. Although this section focuses primarily on the hypermetabolic response, the increased physiologic demands placed on the cardiac, pulmonary, renal, and other organ systems can complicate nutritional support and are noted.The hypermetabolic response that occurs after a trauma, shock, or sepsis is characterized by a hyperdynamic circulatory state, fever, weight loss, and progressive skeletal muscle wasting, and it can remain elevated for weeks after healing is complete. The magnitude of the response parallels the extent of the injury/stress and 7