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Closely monitor electrolyte levels in patients who are being fed after a period of inadequate nutrition.
Initial screening and ongoing assessment of nutritional status are essential aspects of patient care. The screening is usually performed by a nurse but may also be performed by a dietetic technician, registered dietitian, physician, or other qualified health care professional. The purpose of screening is to detect nutritional problems and identify patients who are malnourished or at nutritional risk who may need a more detailed assessment (Table 1). The components of nutritional screening may vary based on the patient population and the setting, but most cases include determining if a patient has a history of weight loss over a specific period or a recent history of poor appetite and inadequate nutritional intake.
Comprehensive assessment of nutritional status involves interpreting data from the initial screening and information obtained during a complete nutritional assessment, anthropometric measurements, and physical examination. Biochemical parameters may offer information on immune function and protein status.
Height and weight help determine nutritional status and are the typical anthropometric measurements used to calculate body mass index (BMI).
The direct measurement of height involves a measuring rod and the patient standing or lying flat. When the patient’s condition prevents such positioning, indirect methods, such as recumbent length, arm span, or knee height, may be used to estimate height.
Body weight is one of the most important measurements in assessing nutritional status and for predicting energy expenditure. Weight changes may indicate nutritional status and may help to estimate risk and make clinical management decisions (Table 2). Weight and body mass information can be evaluated in several ways, including estimating usual body weight, calculating ideal body weight, measuring actual body weight, and calculating BMI. In most cases, obtaining repeated body weight measurements over time is highly recommended to monitor changing trends in weight.undefined#ref6">6 Serial assessment of body weight is easily obtained, inexpensive, and usually acceptable to the patient.6 The magnitude of weight loss is one of the best validated nutritional assessment parameters, and in many cases it is an indicator of underlying disease or an inflammatory condition.6 Percentage of weight change is a useful nutritional assessment parameter and also provides an indirect measure of body adiposity.2 Percentage of weight change is calculated using the following formula:
% weight change =
(usual weight - actual weight) × 100
BMI provides an estimation of adiposity by calculating weight corrected for height. The easiest way to estimate BMI is to refer to a standard BMI chart (Figure 1). BMI may be listed by degree of adiposity (Box 1). However, BMI alone is not a perfect indicator that a person is overweight or obese. Other factors must be considered when evaluating muscular patients (e.g., bodybuilders) and patients with large amounts of edema or ascites because these physiologic states lead to an overestimation of the degree of body fat. BMI may also underestimate fat in older adults.1
No single laboratory test is available for measuring nutritional status or evaluating short-term response to medical nutritional therapy. Along with other assessment data, various laboratory tests conducted over time give more accurate information than a single test. Measuring hepatic proteins (serum albumin, prealbumin, and transferrin) is useful for identifying patients who may become malnourished because of inflammatory processes, which may accelerate nutritional depletion. Although not a direct measure of nutritional status, hepatic proteins indicate the risk of morbidity and mortality.5 In addition, chemistry panels, lipid panels, and hematologic laboratory results may provide information about glucose tolerance, renal function, electrolyte abnormalities related to malnutrition and refeeding syndrome, cardiovascular disease risk, and nutritional anemias, which may indicate a need for nutritional intervention.5
Patients who are identified during the admission process as malnourished or at risk for becoming malnourished should be referred to a registered dietitian. The dietitian can further evaluate the patient and ensure appropriate nutritional intervention and follow-up assessments, including calculation of actual calories required and calories consumed.
The nurse should be aware that patients who have been without adequate nutritional intake for an extended period are at risk for acute electrolyte shifts when adequate diet or enteral or parenteral nutrition is resumed or IV dextrose is administered. This condition, called refeeding syndrome, may cause severe hypokalemia, hypomagnesemia, hypophosphatemia, fluid and sodium retention, and dysfunction of several organ systems. Electrolyte levels in patients who are being fed after a period of inadequate nutrition must be closely monitored.
Rationale: An actual weight is important for nutritional assessment and medication dosing.
Rationale: Significant weight fluctuations or weight outside of normal range indicates nutritional risk. The acceptable range is within 10% above or 10% below ideal body weight.4
Rationale: Abnormal values when considered with other nutritional parameters may indicate malnutrition or refeeding syndrome.
Rationale: Completeness of data obtained from the history and physical findings allows prompt identification of the risk of malnutrition and the need for nutritional interventions.
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