The importance of providing adequate nutrition as an adjunct to medical care was identified as early as the era of Hippocrates. The prevalence of malnutrition in the hospitalized patient was largely ignored until 1974 when Butterworth published his landmark paper entitled “The Skeleton in the Hospital Closet.” 30% to 50% of hospitalized patients are malnourished upon admission, and they tend not to improve nutritionally, and frequently worsen, while hospitalized.
Malnutrition is associated with increased infection rates, longer hospital length of stay, increased hospital costs, and mortality. Therefore, the nutritional status of most patients should be assessed throughout their hospitalizations.
This chapter will provide the hospitalist with a framework for assessing nutritional status, identifying patients at increased risk of malnutrition, and determining the most appropriate nutritional prescription. This chapter will not cover nutrition at the end of life. See Chapter 216 (Palliation of Common Symptoms).
NUTRITION EVALUATION AND SCREENING
Usually a dietitian or nurse uses a nutrition screening questionnaire to assess patients for malnutrition at the time of admission. The assessment process includes a combination of anthropometric measurements, and the history and physical examination. Most validated nutrition screening tools evaluate a combination of body mass index (BMI), recent unintentional changes in weight, recent changes to oral intake, and severity of present illness.
Nutritional screening may identify patients who are underweight and therefore at significant risk for developing nutritionally related complications during treatment of acute illness. However, nutritional screening may fail to identify other patients at increased risk based simply on weight. Patients admitted with volume overload due to heart failure, cirrhosis, or renal insufficiency may have their true dry weight masked by excessive fluid retention. Acutely ill patients who have received aggressive fluid resuscitation gain several kilograms above their true dry weight. Patients whose dry weight is in the obese range may have malnutrition due to protein degradation and loss of lean body mass from rapid weight loss during acute illness.
ANTHROPOMETRIC MEASUREMENTS AND PHYSICAL ASSESSMENT
Anthropometric measurements are a set of noninvasive, quantitative techniques for determining an individual’s body fat composition by measuring specific dimensions of the body, such as height and weight, triceps skin-fold thickness, mid-upper arm circumference, and bodily circumference at the waist, hip, and chest. If such measurements fall below standard norms then one is considered malnourished. For example, health care professionals can compare a patient’s weight to the ideal body weight (IBW) found in tables from various sources, such as the 1952 Metropolitan Life tables. Alternatively, one can use the Hamwi “rule of thumb,” which was developed from the Metropolitan table.
Every patient should have a nutrition assessment when admitted to the hospital.
One assessment is the Hamwi “rule of thumb,” which can be used to compare a patient’s IBW to actual body weight: