CHAPTER 27 Nutritional assessment and support
1. Compare and contrast the pathophysiology and clinical manifestations of protein malnutrition, protein-calorie malnutrition, and obesity.
2. Identify how starvation without injury differs from the metabolic response to starvation with injury.
3. Distinguish between the purpose of a nutrition screening tool and a nutrition assessment tool.
4. Compare and contrast nutritional assessment using Subjective Global Assessment and the Mini Nutritional Assessment.
5. Describe anthropometric and laboratory data that can be used to evaluate whether nutritional support is adequate to support healing.
6. Identify the role of nutrients in wound healing, including requirements for calories, protein, zinc, and vitamin C.
Wound healing is an anabolic process that requires specific nutrients to fuel the biochemical processes in healing (e.g., zinc is required for hydroxylation of proline in collagen formation) (Arnold and Barbul, 2006; Demling, 2009). Although adequate nutrition is important for all patients, it is of particular importance for the patient with a wound to prevent severe or prolonged depletion of nutrients that can impact healing (Arnold and Barbul, 2006). A patient with a wound may lose as much as 100 g of protein per day through wound exudate (Pompeo, 2007). Furthermore, once malnourished, the tube-fed patient in long-term care may require 3 to 4 weeks or longer before protein stores normalize (Pompeo, 2007).
Malnutrition
Nationwide, the prevalence of malnutrition in all hospitals is estimated at between 20% and 50% (Norman et al, 2008), and as many as 69% of patients experience further deterioration of nutritional status during their hospitalization. This prevalence is particularly alarming because malnutrition is associated with increased morbidity (25%) and mortality (5%) in patients with acute or chronic disease as well as longer hospitalization and higher treatment costs compared to patients without malnutrition. Risk factors for malnutrition are listed in Checklist 27-1.
CHECKLIST 27-1 Risk Factors for Malnutrition
✓ Therapeutic dietary restriction
✓ Inability to buy or prepare food
✓ Lack of teeth or poorly fitting dentures
✓ Food intolerance (e.g., as occurs with chemotherapy)
✓ Alterations in ingestion, digestion, absorption, metabolism
✓ Change in pattern or variety of food ingested
✓ Nausea, vomiting, anorexia, diarrhea
Malnutrition is a state in which nutritional deficiency or an imbalance of energy, protein, and other nutrients causes measureable adverse effects on tissue, body structure, body function, and clinical outcome. Malnutrition can be classified as undernutrition or overnutrition, which is caused by a deficit or excess of nutrients in the diet, respectively. Table 27-1 lists the causes and manifestations of the various types of malnutrition.
TABLE 27-1 Causes and Manifestations of Malnutrition
| Type of Malnutrition | Cause | Manifestations |
|---|---|---|
| Protein-calorie malnutrition (marasmus) | Inadequate protein and energy | Gradual weight loss resulting in underweight, then progressive cachexia Visceral protein levels preserved Immune function well preserved |
| Protein malnutrition (kwashiorkor) | Inadequate protein intake and adequate energy intake | Well-nourished appearance Rapid onset with loss of visceral proteins Skeletal muscle mass well preserved Edema |
| Mixed protein-calorie malnutrition (marasmus-kwashiorkor) | Inadequate protein and energy intake | Common in hospitalized patients Acute onset Presents with rapid weight loss, fat and muscle wasting, rapid decline in visceral proteins |
| Obesity | Excessive energy intake | Body mass index >30 Large waist size |
Undernutrition
Undernutrition occurs because intake of macronutrients or micronutrients is inadequate or the individual is unable to absorb or metabolize nutrients that are ingested. Undernutrition most often is related to disease or infirmity (Norman et al, 2008). Some patients are admitted to the hospital with undernutrition due to underlying disease. Others develop undernutrition during hospitalization as a result of decreased intake, the hypermetabolic response that accompanies acute injury and inflammation, or secondary to illness or treatment (e.g., diarrhea, wound drainage).
Undernutrition is generally divided into protein-calorie malnutrition and protein malnutrition. Protein-calorie malnutrition is sometimes called protein-energy malnutrition or marasmus, and protein malnutrition is known as kwashiorkor. Protein-calorie malnutrition is more often seen in developed countries rather than in underdeveloped countries. It affects both adults and children. Protein-calorie malnutrition reflects the inadequate intake, absorption, or metabolism that occurs in persons with chronic illnesses, such as cancer and chronic heart failure, as well as acute and traumatic injury. Severe weight loss, muscle wasting, and loss of adipose tissue characterize protein-calorie malnutrition (Heimburger, 2008).
In contrast, protein malnutrition occurs in persons in whom sufficient protein is not ingested, absorbed, or metabolized. It is often seen in patients with chronic disease, such as chronic obstructive pulmonary disease, heart failure, and cancer (Heimburger, 2008). It also is seen in third world countries where protein sources are scarce.
Starvation.
Starvation occurs when caloric intake is inadequate to meet metabolic needs. The classic picture of someone who is starved is the individual who has inadequate intake, is in an unstressed state, and is hypometabolic (Heimburger, 2008). Initially with inadequate intake, compensatory processes are initiated to meet the glucose needs of essential tissues (e.g., brain, white blood cells). Glycogen that is stored in the liver is mobilized for energy; however, stores are small and are exhausted in less than 24 hours. Subsequently, glucose needed for cellular activities is formed by the catabolism of protein in muscle and tissues. Protein is not stored in the body, so when protein is used for gluconeogenesis, functional muscle and organs are destroyed and weight loss is rapid. Weight loss occurs from both the breakdown of protein and the osmotic diuresis that allows for excretion of the byproducts of protein metabolism in the urine.
If inadequate intake persists, compensatory processes allow fat to become the primary energy source and for protein to be used at a much slower rate (Heimburger, 2008). The brain adapts and uses ketones from fat metabolism for energy, the muscle releases less protein, and the kidneys recycle the end-products of protein metabolism for glucose. Over time, the basal metabolic rate decreases and weight loss is slowed. Protein is converted to glucose for use by only a few tissues (e.g., red blood cells, fibroblasts, renal medulla). Serum protein measures decline gradually (Glasgow and Hermann, 2006).
When fat stores are depleted, protein again becomes the primary energy source and is rapidly depleted. Skeletal muscle size rapidly decreases, and serum protein levels fall. If treatment is not prompt, death will ensue. Table 27-2 compares the type and manifestations of various types of starvation.
TABLE 27-2 Manifestations of Starvation
| Type of Starvation | Manifestations |
|---|---|
| Brief: Protein is primary energy source. | Increased nitrogen in urine Increased urine output Rapid weight loss Decreased muscle mass |
| Prolonged: Fat becomes primary energy source. Protein is spared. | Slow weight loss Slow loss of muscle mass Increased urinary ammonia Decreased urinary nitrogen |
| Premorbid: Protein becomes primary energy source. Ends with exhaustion of protein or nutritional support to reverse the process. | Cachectic appearance Rapid weight loss Decreased arm muscle circumference and skinfold measures Increased creatinine/weight index Increased urinary urea Decreased serum proteins (albumin, transferrin, prealbumin) Decreased immune capacity (decreased lymphocyte count, anergy to recall antigens) |
Stress and starvation.
Injury causes stress, catecholamine release, and increased metabolic rate. The degree of hypermetabolism is directly related to the severity of injury. For example, severe burns cause a greater increase in metabolic rate than uncomplicated surgery (Demling, 2009). The inflammatory response is elicited concomitantly. Cortisol released from the adrenal cortex enhances protein catabolism, amino acid mobilization, and hepatic glucose production (Heimburger, 2008). Cytokines, including tumor necrosis factor, transforming growth factor-β, and interleukin-1 and interleukin-6, contribute to the stress response. While insulin levels are elevated, insulin resistance prevents anabolism. During this period of hypermetabolism, caloric needs increase, and protein requirements increase disproportionately. Hypermetabolic demands decrease gradually, and, if no additional insult occurs, metabolic needs return to baseline within 10 to 14 days of the acute injury.
In the injured but healthy person, inadequate intake for 5 to 7 days usually is not a problem. Surgical patients are an excellent example. A combination of hypermetabolism and starvation occurs due to inadequate intake. The hypermetabolic response is a physiologic response to injury and results in increased energy needs. At the same time, patients initially are provided with intravenous fluids containing 5% glucose (about 200 calories per liter). This administration spares protein but is not able to meet metabolic needs. As oral intake resumes, caloric intake is less than normal, and auto-catabolism occurs to meet metabolic needs. These patients usually have a brief but rapid decrease in weight. When they return to adequate caloric intake, they regain the lost weight (Heimburger, 2008). If the cause of the stress is not resolved, additional stresses occur (e.g., infection) or the individual’s intake does not meet metabolic needs, the patient is set up for a downward spiral.
Overnutrition
Overnutrition results in obesity, which is defined as a body mass index (BMI) >30. The prevalence of obesity in the United States has risen in the last 40 years from 13% to 27% of the adult population. A greater proportion of women than men are obese, and the frequency of obesity is especially high among African Americans, Native Americans, Native Hawaiians, and Hispanics (U.S. Preventive Services Task Force, 2003).
Obese patients may develop problems related to wound healing, such as delayed wound healing, dehiscence, and infection. They often have concomitant medical problems, including diabetes, hypertension, and poor oxygenation from pulmonary restrictive disease (Wilson and Clark, 2004). In addition, because adipose tissue is not as well perfused as muscular tissue, the obese patient is at increased risk for delayed healing and infection. Mobility may be a problem, placing the obese patient at risk for pneumonia, deep venous thrombosis, and pressure ulcers.
The excess weight of an obese patient does not necessarily reflect adequate nutritional health. Protein deficiency as well as deficiencies of vitamins and minerals may be present. Unfortunately, nutritional evaluation of the obese person is often incorrectly deferred simply because his or her weight is so much more than normal (Gallagher and Gates, 2003). However, the obese person with a wound needs exogenous nutrients to heal, and his or her diet must be individualized to meet the patient’s needs.
Screening and assessment
In a healthy state, people ingest sufficient carbohydrates, protein, fat, vitamins, minerals, and fluids to meet nutritional needs and maintain a positive nitrogen balance. Wound healing requires additional nutrients. Because malnutrition is so prevalent in the hospital setting and is associated with significant morbidity and mortality, it is wise to screen patients for possible malnutrition upon admission; ideally it should be done in tandem with the admission assessment. In contrast to screening, nutritional assessment is conducted by a dietitian or a member of the nutrition support team. Nutritional assessment involves a systematic process of collecting, verifying, and interpreting data on the patient’s nutritional status and forms the basis for nutritional interventions (National Pressure Ulcer Advisory Panel [NPUAP] and European Pressure Ulcer Advisory Panel [EPUAP], 2009). Sample screening and assessment forms discussed in this section are provided in Appendix B.
Screening for possible malnutrition
Nutrition screening identifies the patient who is (1) not at risk and therefore is not in need of a nutritional assessment, (2) at potential risk for malnutrition, or (3) possibly undernourished. The latter two are indications of the need for a nutritional assessment by a registered dietician (Anthony, 2008; NPUAP-EPUAP, 2009). For the hospitalized patient, nutritional screening provides baseline data on a person’s nutritional status and should be done at admission or as early as possible following admission (Green and Watson, 2006; NPUAP-EPUAP, 2009). Many screening tests for possible malnutrition are used in patient care, but few have been validated. According to the NPUAP-EPUAP (2009) Pressure Ulcer Prevention and Treatment Clinical Practice Guideline, the nutritional screening tool should be validated, reliable, relevant to the desired patient group, applicable to different health care settings, able to detect undernutrition and overnutrition, and quick and easy to use. The two screening tools recommended by the NPUAP-EPUAP as being the most accurate and readily available for the general hospital and inpatient population are the Malnutrition Screening Tool (MST) and the Short Nutritional Assessment Questionnaire (SNAQ) (Kruizenga et al, 2005) (see Appendix B). Composed of questions that are most predictive of malnutrition, these tools are easy to implement. According to the NPUAP-EPUAP guideline, each health care setting should have a policy on nutritional screening and frequency. The policy should indicate that the patient who is screened as being at risk for malnutrition should be referred to a registered dietician or nutritional support team for a nutritional assessment.
Assessment of nutritional status
Nutritional status is sometimes evaluated entirely based on data from the patient’s history and physical. In these situations, the admission assessment should sequence the history taking so that significant dimensions reflective of nutritional status are clustered. This information can be used to direct the physical examination, laboratory work, and referrals. Checklist 27-2 lists the parameters to address in the patient history.
The physical examination is performed after the history is taken. Although no single physical finding is diagnostic of malnutrition, many different signs and symptoms are associated with specific nutritional alterations, such as coarse hair or thin skin (Seidel et al, 2008). Signs and symptoms associated with nutritional alterations are listed in Table 27-3. However, these findings correlate with other conditions, such as disease process, medication side effects, metabolic alterations, and age-related changes (Heimburger, 2008). Often the physical assessment findings can be used to confirm concerns or suspicions derived from the data obtained from the patient’s history or the laboratory work. For patients at risk of, or with, early malnutrition, the physical findings for malnutrition may be subtle or absent because some signs do not appear until the malnutrition becomes advanced. With overt malnutrition, anthropometric changes often are key findings. Obese patients are especially difficult to evaluate because their weight may mask the skeletal muscle wasting of malnutrition (Gallagher and Gates, 2003).
TABLE 27-3 Physical Findings Associated with Nutritional Deficiencies
| Site | Signs and Symptoms | Nutritional Deficit |
|---|---|---|
| Skin | Cracking | Protein |
| Petechiae | Vitamin C | |
| Scaling | Vitamin A | |
| Hair | Corkscrew hairs | Vitamin C |
| Easily pluckable hair | Protein | |
| Muscles | Weakness | Protein, calories |
| Mouth | Bleeding | Vitamins A, C, K |
| Atrophic tongue | Protein, iron |
Nutritional assessment instruments.
Nutritional assessment instruments are used to capture various pieces of data that collectively will provide an index on the patient’s nutritional status. The ideal nutritional assessment instrument should be sensitive to early changes and specific enough to identify only nutritional causes of the measure; it should be corrected with nutritional intervention, and correction of its values should result in a positive outcome (Barbosa-Silva, 2008; Keith, 2008). In addition, the approach/instrument should be easy to use, readily implemented by various members of the team, and possess sufficient reliability and validity to accurately identify any problems (NPUAP-EPUAP, 2009).
The Subjective Global Assessment (SGA) (see Appendix B), first described in 1982, is a widely used assessment tool with clearly delineated assessment parameters obtained through a focused history (weight change, dietary intake, gastrointestinal symptoms, functional capacity, coexisting disease) and physical examination (subcutaneous fat, muscle wasting, ankle and sacral edema, ascites). Once the SGA is completed, the patient is classified as well nourished (grade A), moderately malnourished or suspected of being malnourished (grade B), or severely malnourished (grade C) (Keith, 2008). The SGA has been reported to consistently predict malnutrition better than objective measures (transferrin, delayed hypersensitivity, skin fold measures, creatinine height index). Originally created for the surgical patient, the validity and reliability of the SGA have been demonstrated in diverse patient populations, including children, the elderly, and patients undergoing dialysis. When the SGA is combined with serum albumin, prediction of malnutrition was more consistent than with either measure alone (Detsky et al, 1994). Although the SGA is a clinically effective and simple tool for nutrition assessment, the grading of malnutrition is subjective and best conducted by a trained clinician.
The Mini Nutritional Assessment (MNA) is a reliable and valid 18-item tool that combines screening with assessment. The MNA consists of anthropometric, general, dietary, and subjective assessments, has been used in a variety of health care settings, and has been shown to detect malnutrition before changes in weight or serum protein levels, especially in an elderly population (Bauer et al, 2008). From a cross-sectional study of elderly patients with pressure ulcers, Langkamp-Henken et al (2005) concluded that use of the MNA was advantageous over serum protein levels for screening or assessment.
Recently the new MNA-Short Form (see Appendix B) has been validated as a stand-alone screening tool; requiring less time to complete and being more user friendly, the MNA-Short Form has become the preferred form for clinical practice (Kaiser et al, 2009). Furthermore, it has been demonstrated that when BMI is not available, the calf circumference is a valid alternative.
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