The Royal Marsden Hospital Manual of Clinical Nursing Procedures - Lisa Dougherty [258]
Skinfold thickness and bio-electrical impedance
Skinfold thickness measurements can be used to assess stores of body fat. They are rarely used in routine nutritional assessment due to the insensitivity of the technique and the variation between measurements made by different observers. They are more appropriate for long-term assessments or research purposes and the technique should only be used by practitioners who are practised in using skinfold thickness calipers because of the potential for intra-investigator variation in results (Durnin and Womersley 1974).
Bio-electrical impedance analysis (BIA) is a simple, non-invasive and relatively inexpensive technique for measuring body composition (Janssen et al. 2000). This technique works well in healthy individuals but may be of limited use in some hospital patients with abnormal hydration status (for example, severe dehydration or ascites) and is also less reliable at the extremes of BMI ranges (Kyle et al. 2004).
Clinical examination
Observation of the patient may reveal signs and symptoms indicative of nutritional depletion.
Physical appearance: emaciated, wasted appearance, loose clothing/jewellery.
Oedema: will affect weight and may mask the appearance of muscle wastage. May indicate plasma protein deficiency and is often a reflection of the patient’s overall condition rather than a measure of nutritional status.
Mobility: weakness and impaired movement may result from loss of muscle mass.
Mood: apathy, lethargy and poor concentration can be features of undernutrition.
Pressure sores and poor wound healing: may reflect impaired immune function as a consequence of undernutrition and vitamin deficiencies (Thomas and Bishop 2007).
Specific nutritional deficiencies may be identifiable in some patients. For example, thiamine deficiency characterized by dementia is associated with high alcohol consumption. Rickets is seen in children with vitamin D deficiency.
A more structured approach can be taken by using an assessment tool such as SGAor patient-generated SGA (PG-SGA) (Bauer et al. 2002). This involves a systematic evaluation of muscle and fat sites around the body and assessment for oedema in the ankles or sacral area in immobile patients. Such an assessment can be used to determine whether the patient is malnourished and can be repeated to assess changes in nutritional status.
Dietary intake
Nutrient intake can be assessed by a diet history (Thomas and Bishop 2007). A 24-hour recall may be used to assess recent nutrient intake and a food chart may be used to monitor current dietary intake. A diet history may also be used to provide information on food frequency, food habits, preferences, meal pattern, portion sizes, the presence of any eating difficulty and changes in food intake (Reilly 1996). A food chart on which all food and fluid taken is recorded is a useful method for monitoring nutritional intake, especially in the hospital setting or when dietary recall is not reliable (Thomas and Bishop 2007).
Biochemical investigations
Biochemical tests carried out on blood may give information on the patient’s nutritional status. The most commonly used are as follows.
Plasma proteins. Changes in plasma albumin may arise due to physical stress, changes in circulating volume, hepatic and renal function, shock conditions and septicaemia. Plasma albumin and changes in plasma albumin are not a direct reflection of nutritional intake and nutritional status as it has been shown that they may remain unchanged despite changes in body composition (NCCAC 2006). In addition, albumin has a long half-life of 21 days, so it cannot reflect recent changes in nutritional intake. It may be useful to review serum albumin concentrations in conjunction with C-reactive protein (CRP), which is an acute-phase protein produced by the body in response to injury or trauma. CRP greater than 10 mg/L and serum albumin less than 30 g/L suggests ‘illness’. CRP