Nutrition Assessment

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Nutrition Assessment

Jami E. Baltz

Nutrition is vital to life, health, and a sense of well-being. Second to the provision of oxygen (O2) to a living organism is the necessity for the provision of nutrients to sustain the function, growth, maintenance, and repair of the human body. A human deprived of air for minutes can no longer function. Similarly, a human deprived of food for days to weeks can no longer function.

Adequate nutrition is essential for health. The relationship between nutrition and respiratory status is reciprocal. A balanced supply of nutrients is needed for proper respiratory function; O2 is required for adenosine triphosphate synthesis and muscle function, including the respiratory muscles. Poor or inadequate nutrient intake disrupts energy use and impairs normal organ function. Conversely, disease can impair nutrient intake or alter metabolism, causing malnutrition.

To heal, traumatized tissue requires the provision of the substrates for healing—that is, nutrients. To achieve a sense of vibrant living for a long life requires daily, consistent attention to providing essential nutrients. A patient with a respiratory condition is particularly challenged to ensure adequate nutrition because it is difficult to breathe and swallow at the same time. This chapter focuses on nutrition assessment—determining the nutrient needs of individuals.

Nutrition Assessment

The process of collecting and evaluating data to determine the nutrition status of an individual is termed nutrition assessment. A registered dietitian or physician trained in clinical nutrition gathers data to compare various social, pharmaceutical, environmental, physical, and medical factors to evaluate the nutrient needs of an individual. The purpose of nutrition assessment is to gather data to develop a nutrition care plan that ensures adequate nutrition for health and well-being when implemented.

Registered dietitians or physicians obtain data from numerous sources for nutrition assessment. Interviewing the individual or the caregiver to determine past and current eating practices is most helpful. Medical charts reveal additional information regarding social, pharmaceutical, environmental, and medical issues. In particular, the ABCDs of nutrition assessment—anthropometrics, biochemical tests, clinical observations, and dietary analyses (described subsequently)—lead to nutrition care plans.1

The social history of an individual includes marital status, employment, education, and economic status. Drug-nutrient interactions may be identified from prescribed medications that lead to potential nutrient deficiencies. Environmental issues could point out the difficulties the individual has in procuring, storing, or preparing food. The education attained by the individual could determine the potential for understanding and applying nutrition counseling. The economic status of the individual may drive certain food choices.2 Box 21-1 presents an overview of the information to incorporate into a nutrition assessment.

Anthropometrics

Anthropometrics refers to measurements of the body. The most frequently used measurements are height and weight. Skinfold thicknesses, arm muscle measurements, waist and hip measurements, head circumference, and wrist diameter are body composition measurements that may be useful when assessing nutrition status.

Height and Weight

A measured height and weight is preferred, but the clinician may ask the patient or caregiver for the height and weight. When the data are recorded, a notation should be made of the date and whether the height and weight were stated or measured. The height and weight can be evaluated to determine weight status by comparing actual body weight with ideal body weight. Table 21-1 shows healthy weights for adults. Ideal body weight may also be determined using the Hamwi formulas. To estimate ideal body weight in pounds, the following simple formulas (Hamwi method) can be used:

TABLE 21-1

Healthy Adult Weights

  Weight (lb)*
Height* Midpoint Range
4′10″ 105 91-119
4′11″ 109 94-124
5′0″ 112 97-128
5′1″ 116 101-132
5′2″ 120 104-137
5′3″ 124 107-141
5′4″ 128 111-146
5′5″ 132 114-150
5′6″ 136 118-155
5′7″ 140 121-160
5′8″ 144 125-164
5′9″ 149 129-169
5′10″ 153 132-174
5′11″ 157 136-179
6′0″ 162 140-184
6′1″ 166 144-189
6′2″ 171 148-195
6′3″ 176 152-200
6′4″ 180 156-205
6′5″ 185 160-201
6′6″ 190 164-216

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Note: The higher weights in the ranges generally apply to men, who tend to have more muscle and bone; the lower weights more often apply to women, who have less muscle and bone.

*Without shoes or clothes.

From Report of the Dietary Guidelines Advisory Committee on the Dietary Guidelines for Americans, Washington, DC, 1995, Government Printing Office.

< ?xml:namespace prefix = "mml" />Men:106lb for the first5ft+6lb for each1in>5ft

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Women:100lb for the first5ft+5lb for each1in>5ft

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A more useful number, the body mass index (BMI), may also be calculated. This number is a handy tool for determining the category of body weight: underweight, healthy weight, overweight, obese, or morbidly obese (Figures 21-1 and 21-2). BMI numerically states the relationship of weight to height. The formula used to calculate BMI is as follows for measurements in kilograms and meters:

BMI=Actual body weight(kg)height2(m2)

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The following formula is used when the weight and height measurements are in pounds and inches:

BMI=Actual body weight(lb)×703height2(in2)

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An Internet calculator for BMI is available at: http://www.nhlbisupport.com/bmi/.

Body Mass Index Categories

A healthy weight is defined as a BMI between 18.5 and 24.9 for adults or a BMI-for-age between the 10th and 85th percentiles for children.2 A BMI of 25.0 to 29.9 indicates excessive weight in adults and a BMI-for-age between the 85th and 95th percentiles indicates excessive weight in children. Obesity is defined as a BMI greater than 30 in adults and greater than the 95th percentile in boys and girls 2 to 20 years old. Adults who are categorized as underweight have a BMI less than 18.5, and underweight children have a BMI-for-age in the 10th percentile (see Figures 21-1 and 21-2).3,4

Kwashiorkor and Marasmus

Undernutrition classifications include kwashiorkor and marasmus. Typically seen in children 6 to 18 months old in deprived areas of the world, marasmus results from an extreme lack of calories and protein over a long time. “Matchstick” arms and obvious lack of muscle and fat characterize a child or adult with marasmus. Kwashiorkor results from a more sudden lack of protein and calories, as in a first-born infant weaned suddenly on the arrival of a new sibling, when a diet of nutrient-rich breast milk is traded for a nutrient-poor, cereal-based diet.2 The protruding belly and edematous face and limbs that are characteristics of kwashiorkor result from a lack of circulating proteins needed to maintain fluid balance and to transport fat out of the liver. Numerous sequelae accompany changes in the liver. Infections and parasites may also cause the enlarged belly seen in kwashiorkor.2 Some patients exhibit combined kwashiorkor and marasmus from protein and calorie deprivation over an extended period. A mixture of loss of muscle and fat and circulating albumin is evident in the extreme wasting and edema that are present.

Body Composition

Other anthropometric measurements useful in nutrition assessment are arm muscle area (index for muscle) and skinfolds (measures of fat), bioelectric impedance analysis devices, and more sophisticated imaging technologies. These methods are generally expensive and time-consuming and are not relevant in the clinical setting but may be more useful in research settings.5

Biochemical Indicators

Laboratory values of particular significance used in assessing nutrition status include serum proteins. PEM may be reflected in low values for albumin, transferrin, transthyretin, and retinol-binding protein. Blood levels of these markers indicate the level of protein synthesis and yield information on overall nutrition status. However, inadequate intake may not be the cause of low values; certain disease states, level of hydration, liver function, pregnancy, infection, and medical therapies may alter laboratory values for each of the circulating proteins.8 Other visceral proteins that may help evaluate nutrition risk are positive acute phase reactants and include fibronectin, insulinlike growth hormone, and C-reactive protein.

Albumin

Albumin constitutes most protein in plasma and is commonly measured at minimal cost. The half-life of albumin is 14 to 21 days, which reduces its usefulness for monitoring the effectiveness of nutrition in the critical care setting.8 The general availability and stability of albumin levels from day to day make it one of the most useful tests for assessing long-term trends (Table 21-2). It is important to determine an albumin value before the onset of disease or insult of injury. In combination with other findings, such as hair pluckability, edema, and poor wound healing, a serum albumin level less than 2.8 g/dl helps differentiate kwashiorkor from marasmus.9 Table 21-3 compares the two forms of PEM.10,11

TABLE 21-2

Assessment of Serum Albumin

Level (g/dl) Interpretation
3.5-5.0 Normal
2.8-3.5 Mild depletion
2.1-2.7 Moderate depletion
<2.1 Severe depletion

TABLE 21-3

Comparison of Two Primary Forms of Protein-Energy Malnutrition

Parameter Starvation (Marasmus) Hypercatabolism (Kwashiorkor)
Etiology Inadequate energy intake Response to injury or infection
Examples Cancer, pulmonary emphysema Sepsis, burns
Body habitus Thin, wasted, cachexic May be normal, edematous
Rate of malnutrition Slow Rapid
Metabolic rate Decreased Increased
Fuel Glucose/fat Mixed
Catabolism Decreased Increased
Gluconeogenesis Increased Markedly increased
Glucagon Increased Markedly increased
Insulin Decreased Increased
Ketogenesis Increased Slightly increased
Catecholamines Unchanged Increased
Cortisol Unchanged Increased
Growth hormone Increased Increased
Visceral proteins Normal Decreased
Cytokines Variable Increased
Immune function Normal Impaired
Clinical course Adequate responsiveness to short-term stress Infections, poor wound healing, decubitus ulcers, skin breakdown
Mortality Low unless related to underlying disease High

Transthyretin and Retinol-Binding Protein

Transthyretin, also called prealbumin, has a half-life of 2 to 3 days, and retinol-binding protein has a half-life of 12 hours. Each of these proteins responds to nutrition changes more quickly than either albumin or transferrin. However, numerous metabolic states, diseases, therapies, and infections influence the laboratory values.13

These two tests are more costly than testing for albumin. Levels of each protein are influenced by many factors other than nutrition status. Because these conditions are so common among critically ill patients, visceral protein markers are of limited usefulness for assessing nutrition deficiency and of greater usefulness in assessing the severity of illness and the risk for future malnutrition.14 Inflammatory metabolism causes a 25% decrease in the synthesis of these visceral proteins and causes lean body mass depletion and anorexia. It is important to evaluate their values with positive acute phase reactants (fibronectin, insulinlike growth hormone, C-reactive protein) where there is a reverse relationship.

Fibronectin, Insulinlike Growth Hormone, and C-Reactive Protein

Fibronectin, a glycoprotein with a half-life of 15 hours, plays an important role in wound healing. Because it is less affected by acute stress than other visceral proteins, it may become an important marker of nutrition status and an indicator of the efficacy of nutrition support.

Insulinlike growth hormone type 1, also called somatomedin C, is not routinely used in the clinical setting at this time in nutrition assessment. However, insulinlike growth hormone type 1 is used to measure protein status routinely in research settings. It may be more effective than other means in measuring nutrition status in the acute phase of stress, and its usefulness may increase.

C-reactive protein is an acute phase protein released with infection and inflammation. As transport proteins (albumin and prealbumin) decrease, levels of the acute phase proteins increase. Increased levels of C-reactive protein during stress, illness, and trauma have been linked to increased nutrition risk.12

Nitrogen Balance (Protein Catabolism)

Approximately 16% of protein is nitrogen, a useful factor in determining nitrogen balance. Because nitrogen is a major by-product of protein catabolism, its rate of urinary excretion can be used to assess protein adequacy. Nitrogen balance is calculated as follows:

Nitrogen balance=Nitrogen intakeNitrogen losses

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Nitrogen intake=Protein intake6.25

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Nitrogen losses=UUN excretion in grams+35g(for insensible losses)

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The conversion factor for dietary protein is 6.25 g of nitrogen per 1 g of protein. The amount of nitrogen excretion in the urine is typically measured as the 24-hour urinary urea nitrogen (UUN). Between 3 g/day and 5 g/day is added to the 24-hour urinary urea nitrogen for an estimate of the average daily unmeasured nitrogen lost through other sources (skin and gastrointestinal [GI] sloughing, hair loss, sweat, feces). Theoretically, by increasing exogenous protein, loss of endogenous protein is reduced. However, because of invalid 24-hour urine collections, alterations in renal or liver function, large immeasurable insensible losses (burns, high-output fistulas, wounds, or ostomies), and inflammatory conditions (generally occurring in critically ill patients), nitrogen balance calculations are inaccurate.

Clinical Indicators

The physical signs of malnutrition often appear first in selected tissues, such as the hair, eyes, lips, mouth and gums, skin, and nails. Hair that is shiny and firmly in the scalp; bright clear eyes that adjust to light easily; an appropriately red tongue without swelling; gums without bleeding or swelling; skin of good color that is smooth and firm; and nails that are pink, smooth, and firm all are signs of acceptable nutrition status. In addition to malnutrition, other causes of these abnormalities might be medical therapies, anemia, allergies, sunburn, medications, poor hygiene practices, aging, or various pathologies.8 Patients with persistent malnutrition often appear very thin to the point that their ribs and bony structures of the chest are very visible. A patient is said to be cachexic in such cases.

Dietary Measures

Past dietary practices need to be identified in the nutrition assessment process. Numerous means are available to determine food consumed by an individual. A registered dietitian may use a 24-hour recall or a usual daily intake recall, a food diary or food record, or a food frequency questionnaire. Each method has advantages and disadvantages.

Evaluation of Nutrition History

A 24-hour recall or usual recall, food diary or record, or a food frequency questionnaire may be evaluated for nutrient intake using the food guide pyramid My Pyramid, a nutrient analysis handbook, or a nutrient analysis software package.

Food Guide Pyramid

The U.S. Department of Agriculture and the U.S. Department of Health and Human Services have cooperated through the years to recommend balanced nutrition for U.S. citizens. The current graphic showing recommendations, My Pyramid,18 divides foods into groups based on the nutrient contribution of the grouping. For example, the grains group consists of breads, pasta, and rice, which all contribute B vitamins, folate, iron, and protein to the diet. The measure (ounces or cups) of servings is recommended for multiple calorie levels of each of the food groups: grains, protein, dairy, fruits, and vegetables. Consuming the recommended amounts of each should provide balanced, adequate nutrition for a healthy person (Table 21-4). The calorie level is based on age, gender, and activity level. The clinician or patient can go to http://mypyramid.gov to enter an individual’s data and be given the recommended calorie level. A comparison of a 24-hour recall with My Pyramid (Figure 21-3) gives an estimation of the adequacy of the patient’s diet.18 Individuals choosing meatless meals may select foods and number of servings from My Vegetarian Food Pyramid (Figure 21-4).19

TABLE 21-4

Dietary Guidelines for Americans—2005

Guideline Application
Adequate nutrients with calorie needs Consume a variety of nutrient-dense foods and beverages within and among the basic food groups while choosing foods that limit the intake of saturated and trans fats, cholesterol, added sugars, salt, and alcohol
  Meet recommended intakes within energy needs by adopting a balanced eating pattern, such as the USDA Food Guide or the DASH Eating Plan
Weight management Maintain body weight in a healthy range, balance calories from food and beverage calories, and increase physical activity
  To prevent gradual weight gain, make small reductions in calorie intake and increase physical activity
Physical activity Engage in regular physical activity
  Achieve physical fitness through cardiovascular conditioning, stretching, and resistance exercises
Food groups to encourage Consume sufficient amounts of fruits and vegetables
  Choose a variety of fruits and vegetables every day
  Consume ≥3 oz equivalents of whole-grain products per day; half of the grains should be whole
  Consume 3 cups per day of fat-free or low-fat milk or equivalent milk products
Fats Consume 10% of calories from saturated fats and <300 mg/day of cholesterol, and keep trans fats as low as possible
  Keep total fat intake between 20% and 35% of calories
  Choose lean, low-fat, or fat-free meat, poultry, dry beans, milk, and milk products
  Limit intake of fats and oils high in saturated and trans fats, and choose products low in such fats and oils
Carbohydrates Choose fiber-rich fruits, vegetables, and whole grains often
  Choose and prepare foods and beverages with little added sugars
  Reduce incidence of dental caries by practicing good oral hygiene and consuming sugars and starches less often
Sodium and potassium Consume <2300 mg of sodium per day (approximately 1 tsp of salt)
  Choose and prepare foods with little salt
  Consume potassium-rich foods (i.e., fruits and vegetables)
Alcoholic beverages Alcohol should be consumed in moderation
  Pregnant and lactating women, individuals who cannot restrict their intake of alcohol, patients taking medications that interact with alcohol, and patients with specific medical conditions should not consume alcohol
Food safety Clean your hands, food contact surfaces, and fruits and vegetables; meats and poultry should not be rinsed
  Separate raw, cooked, and ready-to-eat foods while shopping, preparing, or storing foods
  Cook foods to a safe temperature to kill microorganisms
  Refrigerate perishable food promptly, and defrost foods properly
  Avoid raw (unpasteurized) milk or any products made from unpasteurized milk, raw or partially cooked eggs or foods containing raw eggs, raw or undercooked meat and poultry, unpasteurized juices, and raw sprouts4

Compiled from U.S. Department of Agriculture and U.S. Department of Health and Human Services: Nutrition and your health: dietary guidelines for Americans, Washington, DC, 2005, U.S. Government Printing Office.

Considerations Throughout the Life Span

Pregnancy and Lactation

A healthful diet with added nutrients is essential to a successful pregnancy and to lactation. The demands of the growing fetus and of the nursing infant add to the calorie and protein needs of the mother.22 Ensuring adequate vitamin and mineral intake to support pregnancy and lactation requires a modest increase in all vitamins and minerals compared with the requirements for 19- to 30-year-old women with the exceptions of magnesium; phosphorus; vitamins D, E, and K; and biotin for certain age groups.2326

Children

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