The Stress Response to Injury and Infection: Role of Nutritional Support

The Department of Surgery, Brigham and Women's Hospital, Boston, Massachusetts, and Burn and Wound Program, Health South Braintree Rehabilitation Hospital, Braintree, Massachusetts.

Disclosures

Wounds. 2000;12(1) 

In This Article

Abstract and Introduction

Abstract

The negative impact of the stress response to surgery or illness is well documented. The marked increase in energy demands and rapid erosion of lean body mass lead to significant morbidity including impaired wound healing. The key components of optimal nutritional support for the compromised patient are also well documented. These components include, first and foremost, the assessment and provision of the calories needed to meet energy demands and sufficient protein for protein synthesis, including enough for wound healing. Second, sufficient micronutrients must be provided to optimize metabolism. Third, anabolic hormones can be a valuable addition to nutrition to help restore lean mass and improve healing. Finally, optimizing nutrition is now considered a standard of care for wound management to achieve optimum results.

Introduction

Although the danger associated with acute injury or infection-induced weight loss, especially lean body mass, has been well defined for 50 years, the impact of this process on patient outcome continues to be severely underestimated.[1,2,3,4,5,6,7,8] The focus of management remains that of systemic cardiopulmonary support, infection control, and local wound care, while stress-induced catabolism (protein breakdown) may proceed unchecked, leading to a rapid loss of lean tissue, both muscle and visceral protein. The loss of muscle and visceral proteins begins very early after injury and persists until the injury or infection resolves. It is now clear that the catabolic response to severe injury or post-surgical infection will become auto-destructive if not contained. The severity of complications will occur in proportion to lost body protein. A loss of protein stores exceeding 40 percent is usually fatal ( Table 1 ).

Although major advances in surgical nutrition have been made, attempts at controlling the protein loss often come too little and too late to prevent severe morbidity. The degree of lean tissue loss corresponds very precisely with not only profound weakness but also decreased immune function leading to infection, usually pneumonia. Wound healing becomes markedly impaired, and an open wound soon becomes an infected wound. Often a spontaneous wound develops, e.g., a pressure ulcer, not present until after the lean mass loss occurred.

An aggressive attempt at preventing early protein depletion by controlling the host response to injury or infection and optimizing anabolic activity (protein synthesis) is essential. In order to better understand and manage this process, it is necessary first to define standard terminology then to understand normal body composition and the changes that occur with the stress response. We can then describe the nutritional solution including the role of adjunctive anabolic therapy.

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