Chapter 60: Nutritional Support and Electrolyte Management

INTRODUCTION AND HISTORICAL PERSPECTIVE

Dietary choices impact disease. In the outpatient setting, dietary choices influence our risk for heart disease, cancers, obesity, diabetes, and stroke^1,2; poor dietary choices increase the chance for developing these chronic and acute conditions, many of which are among the leading causes of morbidity and mortality in the United States and the world.^3,4 Five of the 10 leading causes of death in the United States are directly associated with dietary factors (heart disease, cancer, stroke, diabetes, and atherosclerosis).⁵ And dietary interventions can be a primary treatment for these conditions, with outcomes equivalent to or better than drug therapy.⁶

In the inpatient, hospital-based setting, a patient’s nutritional status also impacts clinical outcomes. This notion was first reported in surgical patients in the year 1936, in a study demonstrating that patients with baseline malnutrition undergoing peptic ulcer surgery had mortality rates of 33% compared to 3.5% in well-nourished controls.⁷ This pattern has been reported repeatedly since then, with preoperative malnutrition leading to increased morbidity and mortality in the surgical and trauma literature. With the prevalence of baseline malnutrition among hospitalized medical and surgical patients as high as 40%,^8,9 many patients are at high-risk for poor outcomes and complications.

Anticipating and addressing a hospitalized patient’s dietary needs can therefore substantially impact their disease as well as their outcome. Simply put, providing adequate nutrition is essential to high-quality patient care. Given the extreme physiologic, metabolic, and homeostatic changes that can occur after severe injury, nowhere in medicine is this more true than in trauma, surgery, and critical care.

This chapter is about nutrition, the inflammatory stress responses to injury, and the nutritional needs of the polytrauma patient, for both macro- and micronutrients. The first major section “Nutritional Support” provides a thorough, up-to-date guide on nutrition: first, nutritional needs and requirements are addressed, in both the healthy patient as well as the critically ill, hypermetabolic trauma patient; second, we will outline the specifics of nutritional intervention, including both enteral and parenteral nutritional support; lastly, we cover some special patient populations. The second major section of this chapter, “Electrolyte Management,” is divided into the management strategies of four major electrolytes and their associated abnormalities—sodium and disorders of water balance, potassium, phosphorus, and magnesium.

NUTRITIONAL SUPPORT

Nutritional Needs

Ensuring a patient meets their nutritional needs is vitally important: it is as fundamental to good outcomes as attending to their cardiac function, respiratory status, venous thromboembolism risk, and infection concerns. Addressing the energy and nutrient requirements in the multiple-injured trauma patient requires knowing the needs of a patient in good health as well as knowing how the post-injury inflammatory stress response can impact those needs.

This section is divided into two parts. The first part discusses nutrient utilization and requirements in ...