Nutrition Assessment

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Chapter 21

Nutrition Assessment

Jami E. Baltz

Chapter Objectives

After reading this chapter you will be able to:

Describe how a comprehensive nutrition assessment is conducted.

Describe how to calculate and interpret body mass index.

Describe how to distinguish two forms of protein-energy malnutrition from each other.

List the biochemical indicators of nutrition status.

State what to observe clinically in a malnourished patient.

Describe how to obtain and evaluate a nutrition history.

Describe how to estimate daily resting energy expenditure.

List the indications, contraindications, hazards, and limitations of indirect calorimetry.

Describe how to prepare a patient properly for indirect calorimetry.

Describe how to interpret the results of indirect calorimetry.

Describe how resting energy expenditure values are adjusted to reflect the actual energy needs of a patient.

State the effects of malnutrition on the respiratory system.

Describe how to identify patients at high risk for malnutrition.

Identify the effect of too much protein, carbohydrate, or fat on a patient.

State when enteral nutrition and parenteral nutrition are needed.

Describe how to identify and minimize the common respiratory complications of enteral feedings.

State specific nutrition guidelines that apply to patients with specific pulmonary diseases.

Explain how common pulmonary medications affect nutrition.

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

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

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

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:

FIGURE 21-1 BMI categories for adults. (Modified from U.S. Department of Agriculture and U.S. Department of Health and Human Services: Report of the Dietary Guidelines Advisory Committee for Americans, Washington, DC, 2005, U.S. Government Printing Office.)

FIGURE 21-2 BMI categories for children. (Modified from Whitney EN, Cataldo CB, Rolfes SR: Understanding normal and clinical nutrition (with Info Trac), ed 6, Monteray, CA, 2002, Brooks Cole. Reprinted with permission of Brooks/Cole, a division of Thomson Learning; www.thomsonrights.com.)

BMI=Actual body weight(kg)height2(m2)

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

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

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

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

Overweight and Obesity

Simply defined, overweight and obesity occur over time with the consumption of too many calories or too little expenditure of calories through activity or exercise or both overconsumption and underexpenditure. Other factors may contribute to the accumulation of stored calories, including rare diseases, genes yet to be clearly identified, and loss of mobility through trauma or disease. In any case, too many calories have been ingested for the amount of energy (calories) expended.

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.

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

Transferrin

Transferrin is the transport protein for iron. It has a half-life of 8 to 10 days and is a better indicator of improved nutrition status than albumin. However, lack of iron influences transferrin values along with numerous other factors, including hepatic and renal disease, inflammation, and congestive heart failure.8,12

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

Creatinine-Height Index

Because the rate of creatinine formation in skeletal muscle is constant, the amount of creatinine excreted in the urine every 24 hours reflects skeletal muscle mass. Predicted values are based on gender and height, with reference values of approximately 18 mg/kg body weight/day for women and approximately 23 mg/kg body weight/day for men. Values of 60% to 80% of predicted indicate a mild deficit of muscle mass, values of 40% to 60% of predicted indicate a moderate deficit, and values less than 40% of predicted indicate a severe depletion of muscle mass.⁵ Factors that influence creatinine excretion and complicate interpretation of this index include age, diet, exercise, stress, trauma, fever, and sepsis.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 intake−Nitrogen losses

Nitrogen intake=Protein intake6.25

Nitrogen losses=UUN excretion in grams+3–5g(for insensible losses)

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.

Immune Status

Impaired immunity (anergy) is a common finding in malnutrition, especially the kwashiorkor type. Two laboratory values, white blood cells and percentage of lymphocytes, have been used as measures of a compromised immune system. The result is often a reduction in lymphocytes, as measured by the total lymphocyte count (TLC): TLC = white blood cells × % lymphocytes. Many nonnutrition variables influence these laboratory values, and their usefulness in assessing nutrition status is questioned.¹⁵

Malnourished patients also may exhibit signs of depressed immunity when challenged by certain hypersensitivity skin tests. Because many disease states and drugs are associated with anergy, the value of this test also is limited.¹⁶

Pulmonary Function

Pulmonary function test results may change with malnutrition. Weakness of the diaphragm and other muscles of inspiration can lead to reduced vital capacity and peak inspiratory pressures. The strength and endurance of respiratory muscles are affected, in particular, the diaphragm. Healthy lung function has been correlated with dietary antioxidant intake, such as vitamins C and E, beta-carotene, and selenium.¹⁷

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.

Twenty-four-Hour Recall

The 24-hour recall may be used in an interview in which the patient states the foods and the amount of each food consumed in the previous 24 hours. It is a straightforward commonly used technique that may easily be incorporated into a patient interview. Accuracy of the recall depends on the patient’s memory, the perception of serving size, and the skill of the interviewer to elicit complete information. Spreads, gravies, dressings, beverages, or snacks may be forgotten rendering a nutrient analysis inaccurate (i.e., especially total calories). Patients often report that the previous 24 hours were an aberration in their food intake.

Usual Intake Recall

To improve accuracy, patients may be asked to recall their usual daily food intake. However, neither the 24-hour recall nor usual intake recall method makes allowances for weekends, holidays, celebrations, or other major changes in food intake.

Food Diary or Food Record

The food diary or food record may be used to discover what a patient has been eating. In this case, the patient is asked to write down daily everything he or she has eaten. The patient may record food intake over an extended time, most frequently, a 3-day or 7-day period. Patients arrive with the dietary history in place rather than the interview time being used to reveal dietary practices. However, the act of recording everything eaten influences food choices, reducing the accuracy of a diet history.

Food Frequency Questionnaire

Patients may complete a multiple-item questionnaire choosing foods, serving size, and frequency in which the food was typically eaten to identify their food intake history. Such forms may cover a wide spectrum of foods or foods specifically of interest to current issues. Food frequency questionnaires list commonly used foods in typical serving sizes and often are linked to computer software for ease of analysis of the nutrient content of a patient’s diet. Accuracy of the nutrient analysis depends on the patient’s memory of foods eaten over an extended time and the patient’s perception of the serving size listed versus the serving size consumed.

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.