Nutrition support is a significant component of patient care for hospitalized patients, particularly in the critical care setting. Critical illness is often characterized by a hypermetabolic and systemic inflammatory response including increased infectious morbidity, increased length of hospital stay, multiorgan dysfunction, and finally increased mortality. Historically, nutrition has been a secondary or supportive part of the care for critically ill patients with the goals of preserving lean body mass, maintaining immune function, and averting metabolic complications of critical illness (blunting the catabolic effect of critical illness). Recently these goals have evolved to focus on applying nutrition as a therapy with current goals being to attenuate metabolic response to stress, prevent oxidative cellular injury, and favorably modulate immune response.1,2 The importance of nutrition support as a therapy is becoming more readily apparent with advances in evidence-based medicine. However, there are many factors to consider when determining an appropriate comprehensive nutrition therapy plan for each critically ill patient.
Consulting a registered dietitian or nutrition support team for expert care is paramount to maximizing nutritional support and its associated benefits for the critically ill patient. Early involvement of these practitioners in patient care allows for management of aspects of nutrition support as large in scope as meeting macronutrient needs (the necessary calorie and protein provision for recovery) to the finest nuances of micronutrient, vitamin, and mineral provision. The nutrition support practitioner adjusts the nutrition support regimen throughout the changing and, at times, complex course of the critically ill patient. He or she tailors the frequency of intervention and reassessment to meet the needs of each individual patient as the patient progresses through critical illness.
Assessment of nutrition status involves several components:
- Subjective information
- Physical exam
- Laboratory values
- Calculation of calorie and protein requirements
Subjective information can include, but is not limited to, diet and weight history, social history as it relates to nutrient intake, chronic diseases that may alter nutrient intake, absorption, and utilization, use of medications, etc. Physical assessment will include subjective global assessment of the patient.
Anthropometrics not only gives us a sense of one's weight in relation to height by determining ideal body weight (IBW) and body mass index (BMI), but also helps us begin to determine our patient's nutritional state by revealing if one is overweight, obese, or with baseline malnutrition (see Table 48-1). Determination of IBW and %IBW is important in the formulation of nutrition therapy goals as they are applied to many predictive equations commonly utilized in critical care to estimate patients' calorie and protein requirements.
Table 48-1. Malnutrition Classification |Favorite Table|Download (.pdf)
Table 48-1. Malnutrition Classification
|Malnutrition Classification||IBW Assessment (%)||BMI Assessment|
|Class I obesity/mild obesity||30–34.9|
|Class II obesity/moderate obesity||35–39.9...|