Nutritional Management in the Rehabilitation Setting

Updated: Apr 04, 2023
  • Author: Segun Toyin Dawodu, JD, MD, MS, MBA, LLM, FAAPMR, FAANEM; Chief Editor: Stephen Kishner, MD, MHA  more...
  • Print

Practice Essentials

Nutritional management of patients in a rehabilitation setting often involves dealing with patients on a nutritional spectrum ranging from debilitated individuals who are undernourished to patients who have been admitted for complications of obesity.

Evaluation of nutritional status

Height and weight measurements are probably the most important set of vital signs in nutritional assessment.


Formulas for the calculation of ideal body weight (IBW) based on patient height include the following:

  • Hamwi calculation: Appropriate for patients aged less than 65 years; this calculation is adjusted for gender

  • Metropolitan scale (1959): Weights were obtained from approximately 5 million healthy life insurance policyholders who were tracked by insurance companies for approximately 20 years

  • Geriatric Weight Scale: For patients aged more than 65 years

No matter which calculation method is used, the IBW needs to be adjusted for frame size, spinal cord injury (SCI), and amputation.


The following calculation can be used to determine whether IBW or actual body weight (ABW) should be employed in feeding calculations:

  • Percentage IBW = (actual body weight [ABW]/IBW) x 100

The following parameters can then be used:

  • If ABW is less than IBW, use ABW to determine nutritional needs

  • If ABW is greater than IBW but less than 120%, use IBW to determine nutritional needs

  • If ABW is greater than 120% of IBW, use the adjusted or relative body weight to calculate needs: IBW + (ABW - IBW x 0.25)

Protein status

Visceral and somatic protein status are used as biochemical indices in the evaluation of nutritional status. Visceral proteins used in such assessments include the following:

  • Albumin: Not a definitive measure of visceral protein status, but it reflects the complex relationship between synthesis, degradation, and distribution

  • Transferrin: Makes a better nutritional marker of visceral protein status than does albumin owing to transferrin’s shorter half-life (8-9 days) and smaller body pool size

  • Prealbumin: Excellent nutritional marker owing to its small total body pool and very short half-life (2 days)

Nitrogen balance

Nitrogen balance studies measure the net change in the body's total protein. An estimate of nitrogen balance can be obtained by measuring urinary urea nitrogen (UUN) and comparing it with nitrogen intake during that same time.

Hematologic measurements

Serum hemoglobin and hematocrit may reflect a generalized state of malnutrition.


Malnutrition can be categorized using the following terms:

  • Marasmus: Applies to a typical starved patient

  • Kwashiorkor: Applies to a typical hypermetabolic or catabolic patient

  • Protein/calorie malnutrition: Typically applies to a marasmic patient who becomes hypermetabolic or catabolic

Calculation of nutritional needs

Energy needs

The Harris-Benedict formula has for many years been considered the criterion standard for predicting calorie requirements in acutely ill, hospitalized patients, although it may overestimate energy needs. Requirements are calculated as follows:

  • (Basal energy expenditure [BEE]) x (activity factor) x (injury factor)

Protein needs

The following factors need to be considered when estimating protein needs:

  • Metabolic rate

  • Body protein reserves

  • Calorie intake

  • Nutritional status

  • Disease state

  • Stress associated with critical illness

  • Age

Hydration or fluid needs

These must be addressed within each nutritional assessment because they affect lab interpretation and nutritional intervention. Various methods exist to determine fluid requirements, including calculations based on weight, age and weight, energy, and fluid balance.

Nutritional intervention

Nutritional intervention plans usually follow a progression from oral to enteral to parenteral, as follows:

Oral nutrition

This is the starting point of all interventions. It consists of dietary change, as well as the addition of between-meal snacks and nutritional supplements.

Enteral nutrition

A patient with a functional gastrointestinal (GI) tract is a candidate for enteral support when he or she will not, should not, or cannot take nutrition orally. Enteral feeding can be nasogastric or nasoduodenal/nasojejunal or can be administered via gastrostomy or jejunostomy.

Parenteral nutrition

Parenteral nutritional support is indicated for patients with a nonfunctioning GI tract and an inability to tolerate oral or enteral nutrition. Types of parenteral nutrition are as follows:

  • Peripheral parenteral nutrition (PPN): Considered to be a short-term/adjunct intervention; a time frame of less than 14 days is recommended

  • Total parenteral nutrition (TPN): Intended for full nutritional support; it is recommended for a minimum of 7 days for improvement in patient outcome to occur



Nutrition in a rehabilitation setting often involves patients who could be on either end of the nutritional spectrum, with debilitated patients who are undernourished at one end, and patients who have recently been admitted for complications of obesity, such as coronary artery disease and stroke, at the other end. In between are patients in whom current clinical conditions require optimum nutritional support for recuperation and to enable effective participation in rehabilitation exercise programs.

This discussion will focus mainly on relevant nutritional issues ranging from standard nutritional intervention to aggressive nutritional support, available nutritional interventions, and the process of nutritional screening and support as they pertain to rehabilitation medicine.

There is no discussion of nutritional rehabilitation per se, but some of the issues discussed are of great relevance.

While nutritional support is often through the oral route, there may be instances in which this route is not available and others may need to be used.

There are special nutritional issues peculiar to the elderly and mentally handicapped owing to a variety of factors, such as poor intake, poor chewing abilities, swallowing difficulties, [1] associated debilities, and mental apathy.

In an international, prospective, observational cohort study, Jones et al examined whether practices in 158 adult intensive care units (ICUs), in 20 countries, were similar to Canada's evidence-based Critical Care Nutrition Clinical Practice Guidelines. [2] According to the report, which involved nearly 3,000 mechanically ventilated adult patients, practices regarding the preferential use of enteral nutrition over parenteral nutrition, glycemic control, and the administration of hypocaloric parenteral nutrition were particularly close to guideline recommendations.

However, other practices in the units often were not in sync with the guidelines. For example, practices regarding the use of glutamine supplementation and fish oil–enriched enteral formulas, the timing of supplemental parenteral nutrition, and the avoidance of soybean oil–based parenteral lipids coincided poorly with the guidelines. Moreover, the average nutritional adequacy for energy and protein was 59% and 60.3%, respectively, among the ICUs.


Nutritional Screening

Malnutrition in the hospital setting exists today despite numerous advances in the medical and nutritional arenas. [3] Surveys have found that 40-50% of patients admitted to hospitals are at risk for malnutrition and up to 12% are severely malnourished. These statistics probably represent a fair number of the patients who transfer from the acute care wards to the rehabilitation unit for ongoing treatment. These patients tend to be debilitated as well.

Nutritional screening has become a primary tool to identify at-risk patients and should be performed when the patient is admitted to a rehabilitation unit. While a standard nutritional screening tool has not been established, there are several tools available that can be incorporated easily into routine clinical practice.

It is often necessary at a minimum to do a mini-nutritional assessment of the patient at the point of admission into a rehabilitation unit, since poor nutritional status could lead to greater debility and an inability to fully participate in intensive in-patient rehabilitation therapies. Assessments include the following:

  • Nutrition Screening Initiative (NSI) (1990): This tool offers bilevel screening, using the Body Mass Index (BMI) and a subjective interview on level I. Anthropometric data, laboratory data, clinical history, and medication history are added on level II.

  • Prognostic Nutritional Index (PNI) (1980): This screening model relates the risk of operative morbidity and mortality to baseline nutritional status.

  • Nutrition Risk Index (NRI) (1991): This screen calculates the risk of malnutrition using weight and albumin levels.

  • Subjective Global Assessment (SGA) (1982): This assessment tool maintains that a "carefully performed history and physical are sufficient for nutritional assessment." The history factor reviews weight change, dietary intake, gastrointestinal (GI) symptoms, functional capacity, and disease state in relation to nutritional requirements. The physical examination looks at loss of subcutaneous fat, muscle wasting, edema, and ascites.

Screening Criteria

The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) specifies that nutritional screening should be completed within 24 hours of admission of all hospital patients. This standard ensures that nutrition is addressed early and that intervention is provided in a timely manner and on an ongoing basis. Patients considered to be at nutritional risk may exhibit any of the following :

Actual or potential for developing malnutrition

  • Involuntary weight loss

    • Loss of more than 10% of usual body weight within 6 months

    • Loss of more than 5% of usual body weight within 1 month

    • Patient at 20% more or less than ideal body weight (IBW)

  • BMI < 18; BMI is calculated using the equation Wt (kg)/ht (m2).

Visceral protein depletion

  • Serum albumin < 3.5 g/dL

  • Serum transferrin < 200 mg/dL

  • Serum cholesterol < 160 mg/dL

  • Serum prealbumin < 15 mg/mL

  • Creatinine Height Index (CHI) < 75%

The patient is receiving total parenteral nutrition (TPN) or enteral nutrition (EN).

Inadequate nutrition intake resulting from any of the following factors:

  • Orders for nothing by mouth (NPO) x 3 days

    • Clear liquid diet x 5 days

    • Malabsorptive disorder

    • Impaired ability to ingest

    • Increased metabolic requirement

  • GI disturbances

    • Nausea

    • Vomiting

    • Diarrhea

    • Constipation


Nutritional Assessment

Patients who are considered to be at nutritional risk are required to undergo a comprehensive nutritional assessment, a process consisting essentially of the following 4 steps:

Patient/family interview

A patient/family interview must be conducted. The subjective data obtained during this initial interview are probably the most important component of the assessment process.

If time is not taken to obtain information about the patient's food, cultural, and meal pattern preferences, any intervention is likely to fail, as it has not been individualized to the patient.

This interview is also an ideal time to discuss the patient's nutritional history, including weight, intake, activity level, and feeding disabilities, as well as to complete a physical nutritional assessment.

Objective data collection

The objective data are the most easily obtainable data because they can be found in the medical record.

The objective data include information such as the patient's height, weight, laboratory test values, pertinent medications, medical condition, and rehabilitation goals.

Analysis of objective data

The challenge here is to analyze the objective data.

The objective data should help to determine the patient's nutritional status, nutritional needs, the most appropriate diet, the need for snacks and/or supplements, and when to recommend aggressive nutritional support.

Nutritional intervention

Intervention must be tailored to the patient's needs as determined during the subjective and objective data collection.

The key to a successful intervention and treatment plan is the synthesis of the patient's wants with his or her needs.

At no time should the clinician be satisfied with the status quo. Interventions need to be updated frequently to keep the patient interested in eating and to make continued progress toward nutritional goals.


Evaluation of Nutritional Status

Height and weight measurements are probably the most important set of vital signs in nutritional assessment.


A patient's height is the key component in the determination of IBW. (See information below on the determination of IBW using one of three methods). No matter which calculation method is used, IBW needs to be adjusted for frame size, spinal cord injury (SCI), and amputation, as follows:

  • Frame size

    • Small frame size - Decrease IBW by 10%

    • Medium frame size - No changes needed in IBW

    • Large frame size - Increase IBW by 10%

  • SCI

    • Paraplegia - Decrease IBW by 10-15 lbs

    • Tetraplegia - Decrease IBW by 15-20 lbs

  • Amputation

    • Hand - Decrease IBW by 7%

    • Forearm and hand - Decrease IBW by 2.3%

    • Total arm - Decrease IBW by 4.9%

    • Foot - Decrease IBW by 1.5%

    • Calf and foot - Decrease IBW by 5.8%

    • Total leg - Decrease IBW by 16%

Methods of calculation

  • Hamwi calculation - This method is appropriate for patients aged less than 65 years and has been adjusted for gender.

    • Males

      • 106 lbs for the first 5 feet and 6 lbs per inch thereafter

      • Example - 5'10" = 166 lbs

    • Females

      • 100 lbs for the first 5 feet and 5 lbs per inch thereafter

      • Example - 5'10" = 150 lbs

  • Metropolitan scale (1959)

    • Weights were obtained from approximately 5 million healthy life insurance policyholders who were tracked by insurance companies for approximately 20 years.

    • Frame sizes were not measured in any subject.

    • Weights associated with the greatest longevity were assigned to the medium frame category.

  • Geriatric Weight Scale - This scale is for patients aged more than 65 years. It has been adjusted from the stringent weight recommendations of the Metropolitan scales to accommodate an aging population.


Body weight at admission is probably the most reliable weight when determining a patient's actual body weight, assuming that weight is a dry body weight. Weight status becomes an unreliable measure postoperatively or during an acute crisis, because of the administration of fluids or the development of an edematous state. As a chronic marker, one can assume that a weight gain or loss is related to an increase or decrease in lean body mass.

  • To determine the weight to use for feeding calculations, first derive a figure by calculating the percentage of IBW.

    • Percentage IBW = (actual body weight [ABW]/IBW) x 100

      • If ABW is less than IBW, use ABW to determine nutritional needs.

      • If ABW is greater than IBW but less than 120%, use IBW to determine nutritional needs.

      • If ABW is greater than IBW and more than 120%, use the adjusted or relative body weight to calculate needs: IBW + (ABW – IBW x 0.25).

The following scale presents categories of the nutritional status of patients, using ABW as a percentage of IBW:

  • More than 200% of IBW = morbidly obese

  • More than 150% of IBW = obese

  • More than 120% of IBW = overweight

  • 100% of IBW +/- 10% = normal

  • 80-90% of IBW = mild malnutrition

  • 70-80% of IBW = moderate malnutrition

  • Less than 70% of IBW = severe malnutrition

The BMI is a very practical and useful measurement that allows easy determination of categories of weight status.

Table 1. Weight Classifications (Open Table in a new window)


BMI (kg/m2)

Obesity Class


< 18.5











Moderate obesity



Extreme obesity



Protein Status

Measurements of visceral and somatic protein status are biochemical indices used to evaluate nutritional status. Visceral protein parameters include albumin, transferrin, and prealbumin. According to Charney, serum albumin is perhaps "the most studied biochemical parameter used in nutrition screening and assessment." [4] Albumin is an osmotic protein that constitutes 40% of the total body protein pool of 4-5 g/kg and is maintained largely in the intravascular compartment, with the remainder distributed in extravascular tissues. The serum albumin level is not a definitive measure of visceral protein status, but it reflects the complex relationship between synthesis, degradation, and distribution. Key albumin levels are distributed as follows:

  • Normal levels are 3.5-5.0 g/dL.

  • A level of 3.0-3.5 g/dL is considered to be a nutritional decision point, or a point when nutritional intervention should be considered or adjusted.

  • Levels that are less than 3.5 g/dL have been correlated with poor surgical outcome, unfavorable prognosis, increased cost of hospitalization, and prolonged ICU stay.

  • Levels that are less than 3.0 g/dL are often associated with severe malnutrition.

  • Levels that are less than 2.5 g/dL are associated with increased rates of morbidity and mortality.

Albumin does have limitations as a nutritional marker because of its lengthy half-life of 21 days and the numerous factors that decrease albumin levels, independent of nutritional status. Non-nutritional factors that affect albumin levels include the following:

  • Inadequate synthesis, as seen in cirrhosis, some cancers, acute stress, congestive heart failure, and hypoxia

  • Impaired digestion, as seen in pancreatic insufficiency and malabsorption

  • Altered fluid status, such as that found in edematous condition and overhydration

  • Chronic protein loss, as found in nephrotic syndrome and with burns

Because of its long half-life, serum albumin cannot be used effectively for monitoring acute response to nutritional therapy. Albumin levels should be included on the initial chemistry profile for nutritional screening purposes and monitored during hospitalization for visceral protein repletion trends or as a chronic marker for nutritional status.

Owing to its shorter half-life (8-9 d) and smaller body pool size, transferrin makes a better nutritional marker of visceral protein status than does albumin. Normal levels of transferrin range between 200-400 mg/dL, and a level of 150 mg/dL is considered a nutritional decision point, or a point when nutritional support should be considered or adjusted.

Transferrin levels are decreased in the following situations:

  • Impaired synthesis, which can result, for example, from acute fasting, chronic infection, or pernicious anemia

  • Increased excretion, as with nephritic syndrome, inflammation, burns, and liver damage

  • Overhydration

  • Increased iron stores, as with hemosiderosis and hemochromatosis

Transferrin levels are increased in the following situations:

  • Decreased iron stores, as with iron deficiency anemia and chronic blood loss

  • Increased protein synthesis, which is seen in estrogen therapy and oral contraceptive use

  • Dehydration

  • Pregnancy – 2nd and 3rd trimesters

The serum concentration of transferrin is about 0.8 times the total iron binding capacity (TIBC). If the direct measurement of transferrin is not possible because of the high cost and limited availability of the equipment needed, the transferrin level can be easily calculated from the TIBC, using the following formula:

  • TIBC x 0.8 – 43 = Transferrin

The third measure of visceral protein is prealbumin, which is synthesized in the liver and catabolized in the kidney. Prealbumin has a small total body pool and a very short half-life (2 d), making it an excellent nutritional marker. Prealbumin has been used increasingly as a marker of response to nutritional therapy.

Reference range values for prealbumin are from 16-35 mg/dL. A nutritionally significant value of prealbumin is 11 mg/dL. A value below this level signifies malnutrition. The failure to increase prealbumin above 11 mg/dL with nutritional therapy is an indication that nutritional needs are not being met. Concentrations should increase nearly 1 mg/dL daily or should double in a week when adequate therapy is being provided. Non-nutritional factors that decrease prealbumin include the following:

  • Stress

  • Inflammation

  • Surgery

  • Cirrhosis

  • Hepatitis

  • Renal failure

Table 2 summarizes the 3 visceral proteins in relation to the degree of malnutrition.

Table 2. Degree of Malnutrition (Open Table in a new window)







Albumin (g/dL)

21 days




< 2.1

Transferrin (mg/dL)

8-9 days




< 100

Prealbumin (mg/dL)

2 days




< 5

Somatic protein measurements include the CHI and nitrogen balance studies. Protein status can be assessed biochemically by using the CHI, which measures the 24-hour urinary creatinine excretion and compares it to an ideal value based on ideal weight for height.

Nitrogen Balance Studies

Nitrogen balance studies measure the net change in the body's total protein. An estimate of nitrogen balance can be obtained by measuring urinary urea nitrogen (UUN) and comparing it to nitrogen intake during that same time.

  • Nitrogen balance is calculated as follows: N2 balance = N2 intake – N2 excretion Or = [protein (gm)] – (24 hour UUN + 3)

  • [6.25 gm nitrogen]

  • A "fudge factor" of 3 is added to account for the insensible nitrogen losses in the feces, skin, and drainage of body fluids.

If calculated nitrogen balance equals the following:

  • Nitrogen balance = 0

    • This signifies nitrogen balance.

    • Healthy adults usually are in nitrogen balance.

  • Nitrogen balance >0

    • A positive nitrogen balance is indicated.

    • Protein anabolism exceeds protein catabolism.

    • This is usually seen with pregnancy, growth, and recovery from illness and/or nutritional repletion.

    • The goal in nutritional repletion is a positive nitrogen balance of 4-6 grams per day.

  • Nitrogen balance < 0

    • Negative nitrogen balance

    • Protein catabolism exceeds protein anabolism

    • Observed in situations of starvation, increased catabolism resulting from trauma or surgery, and inadequate nutrition therapy

Hematological Measurements

Serum hemoglobin and hematocrit may reflect a generalized state of malnutrition. As with the visceral and somatic visceral proteins, non-nutritional factors (eg, blood loss, chronic infection, overhydration) must be considered as a potential etiology of decreased serum concentrations.


The determination of malnutrition can be categorized using the following definitions:

  • Marasmus - This term refers to a typical starved patient.

    • Malnutrition is characterized by the following:

      • Deficiency in total calorie intake

      • Preservation of visceral protein production

      • Depletion of somatic protein (skeletal muscle and adipose stores)

      • Impairment of cell-mediated immunity and muscle function

  • Kwashiorkor - This is a typical hypermetabolic or catabolic patient.

    • Malnutrition is characterized by the following:

      • Adequate calorie intake but deficient protein

      • Depletion of visceral protein pools

      • Some depletion of somatic protein with relative preservation of adipose tissue

      • Possible impaired immune function

  • Protein/calorie malnutrition - This typically is a marasmic patient who becomes hypermetabolic or catabolic. This could also occur in circumstances where there is a decreased oral intake of food for a prolonged period of time.

    • Malnutrition is characterized by the following:

      • Depletion of visceral protein pools

      • Depletion of somatic protein and adipose tissue

      • Reduced immunocompetence that may be caused by such factors as a global decrease in body protein, including globulins, and a decreased production of T-lymphocytes. The exact relationship between nutritional status and immunity in hospitalized patients has not yet been fully explained.


Calculation of Nutritional Needs

Nutritional needs include the need for energy, the need for protein, and the need for hydration, with vitamins and electrolytes part of the essential requirements.

Energy Needs

Energy requirements are assessed in a variety of ways. The Harris-Benedict formula has for many years been considered the criterion standard for predicting calorie requirements in acutely ill hospitalized patients, although it may overestimate energy needs. The formula is outlined in the following sample calculations:

Harris-Benedict Formula

See the list below:

  • (Basal energy expenditure [BEE]) X (activity factor) X (injury factor) - BEE is estimated by sex using the following formula:

    • Males: 66.5 + 13.8(wt) + 5.0(ht) - 6.8(age)

    • Females: 655.1 +9.6(wt) + 1.8(ht) - 4.7(age)

  • Activity factor

    • Chair- or bedbound – 1.2

    • Out of bed – 1.3

  • Injury factor

    • Anabolism – 1.5

    • Burn – 1.5-2.1

    • Cancer – 1.1-1.45

    • Closed head injury – 1.3

    • Elective surgery - 1.0-1.1

    • Fever – 1.2 per 1 degree (>37° C)

    • Major surgery - 1.6

    • Mild infection – 1.2

    • Moderate infection – 1.4

    • Multiple long bone fractures – 1.1-1.3

    • Sepsis – 1.2-1.4

    • Starvation – 0.7

    • Low stress – 1.3

    • Medium stress – 1.5

    • High stress – 2.0

Jeejeboy and Cerra suggest an alternative approach that uses body weight (kg) alone as the key determinant and omits the variable of age, sex, and height as used in the Harris-Benedict formula. This type of estimate has been proven to be accurate and time efficient.

Another technique, using indirect calorimetry to calculate energy expenditure, employs the measurement of respiratory gas exchange. Using a metabolic cart, this method allows the measurement of VO2 to calculate 24-hour BEE, as O2 use is directly proportional to energy use in aerobic environments. This technique is useful in burn and septic patients because it allows the clinician to specialize macronutrients based on substrate use.

Two groups of researchers — Ireton-Jones and Turner and Owen and colleagues — developed specific formulas for the obese patient. [5, 6] Standard formulas may overestimate their needs because of the increased fat mass in this population.

Protein Needs

The following factors need to be considered when estimating protein needs:

  • Metabolic rate

  • Body protein reserves

  • Calorie intake

  • Nutritional status

  • Disease state

  • Stress associated with critical illness

  • Age

Two ways to determine protein needs based on stress levels follow.

Formulas Based on Stress

Table 3. Blackburn's General Guide for Protein Needs Based on Stress level (Open Table in a new window)


Estimated Requirements

Normal (RDA)

0.8-1.0 g/kg/day

Moderately stress

1.0-2.0 g/kg/day

Severely stressed

2.0-3.0 g/kg/day

Table 4. Cerra's Guide for Protein Needs Based on Stress level (Open Table in a new window)

Stress level

Clinical Setting



Simple starvation



Elective surgery








Certain disease states have different protein requirements.

Table 5. Disease States and Protein Requirements (Open Table in a new window)

Disease State




Hepatic encephalopathy

0.6 (increase as tolerated to


Renal failure (on dialysis)


Renal failure (not on dialysis)


Chronic liver disease


Nephrotic syndrome


Ulcerative colitis


Refeeding syndrome






Multiple trauma


Major burn


Acute burn/injury/trauma


Hydration or Fluid Needs

This must be addressed within each nutritional assessment because it effects lab interpretation and nutritional intervention. Several methods exist to determine fluid requirements. The most common ones are listed below.

Table 6. Fluid Requirements (Open Table in a new window)

Based Upon

Method of Fluid Estimation


100 mL/kg body weight for first 10 kg

50 mL/kg body weight for next 10 kg

20 mL/kg body weight for each kg above 20 kg

Age and weight


16-30 years, active:

20-55 years:

55-75 years:

>75 years:

40 mL/kg body weight per day

35 mL/kg body weight per day

30 mL/kg body weight per day

25 mL/kg body weight per day


1 mL per kcal

Fluid balance

Urine output + 500 mL per day

From the Manual of Clinical Dietetics, 6th ed. Chicago, Ill: American Dietetic Assn; 2000


Nutritional Intervention

Oral Nutrition

When a patient is hospitalized, whether as an acute or a rehabilitation admission, oral intake is altered from the norm. Hospital food may be unacceptable, or it may be tolerable, but it is never exactly what the patient is accustomed to eating at home. Sometimes patients do eat 100% of their meals. These patients are usually the exception and are typically categorized as "not at nutritional risk." Some patients may start out in this category, but during a lengthy admission, intake can begin to decline.

Nutritional intervention plans usually follow a progression from oral to enteral to parenteral. Oral nutrition is the starting point of all interventions. If the gut works, use it. Oral nutritional intervention consists of dietary change, as well as the addition of between-meal snacks and nutritional supplements.

A regular diet at any facility is considered a balanced diet with respect to the major macronutrients and food groups. It meets the nutritional needs of a general population, which consist of approximately 55% of calories coming from carbohydrates, 15% coming from protein, and 30% coming from fat. The regular diet has no alterations in texture, no specialized foods, and no electrolyte/mineral restrictions.

Therapeutic diets are an alteration from the regular diet. Some examples of therapeutic diets are illustrated in Table 7.

Table 7. Therapeutic Diets (Open Table in a new window)


Diet Composition


Fat restricted

< 50 g fat/d

Diarrhea, steatorrhea,

abdominal pain, pancreatitis,

Crohn disease, chronic


High fiber

20-35 g fiber/d;

decreased amount of simple sugars

Diverticular disease, colon cancer, constipation, irritable bowel syndrome, hypercholesterolemia

Low residue

< 10 g of fiber/d; no nuts, seeds, legumes; limited dairy to 2 cups/d

Diverticulitis, ulcerative colitis, Crohn disease

High protein/calorie

Additional protein/calories

added to regular diet

Cancer, weight loss, malnutrition, hypoalbuminemia, burns, hypercatabolic state

Sodium restricted

500 mg to 4 g sodium/d

(per MD order)

CHF, anasarca, renal disease, HTN, cardiovascular disease,

liver disease

Fluid restricted

(500-2000 mL/d)

(per MD order)

CHF, anasarca, renal disease, liver disease


4 g sodium; < 300 mg

cholesterol/d; 30% calories from fat; saturated fat < 10% of calories

Cardiovascular disease


60 g protein; 2-3 g sodium; 2-3 g potassium; 1000 mg phosphorus; +/- fluid restriction

Renal disease:

Acute - restricted protein

Chronic - no protein restriction


Consistency of food is

liquid, pureed, or semi-solid

Postfacial/oral surgery,

esophageal stricture, dysphagia, edentulous, ill-fitting dentures

The goal of a prescribed diet is to optimize intake while the patient is hospitalized, to promote wound healing and to provide enough energy to allow the patient to undergo therapy. A therapeutic diet may be contraindicated despite the fact that the patient's history includes an illness that generally calls for dietary alterations. Many of the diets listed above are unpalatable because of their composition and are limited in the variety of foods that can be provided. Optimal nutrition cannot be achieved if the patient is not inspired to eat the foods provided.

Complicated diet prescriptions need to be the exception, not the rule. The more diets that are prescribed (eg, mechanical soft, cardiac [sodium/cholesterol restricted], renal [protein/potassium/phosphorous restricted] with a 2-liter fluid restriction), the less likely it is that a patient will eat.

Nutrition is the 1 treatment modality over which the patient usually has control. A liberal attitude should be maintained, providing a diet that the patient will eat but that will not endanger his or her condition.

Adjusting a patient's diet is the initial intervention. If intake does not improve with dietary modification, the next step is to provide between-meal snacks. Again, snacks should be provided based on the patient's preferences, not arbitrarily given. Snacks differ from facility to facility, but they usually are given 3 times per day, at morning, afternoon, and evening intervals. Small, frequent meals should be provided, since this generally optimizes daily intake. Snacks are a very cost-effective intervention.

The provision of a nutritional supplement is definitely not a first-line management technique for poor oral intake. Supplements should be an alternative rather than an automatic intervention. When prescribed appropriately, supplements easily can optimize intake. The goal is to provide a supplement that is appropriate to the patient's condition and that the patient will consume. Supplements should never be overprescribed. Nothing is more overwhelming to a patient than constantly receiving supplements and having them pile up by his or her bedside. This tends to have the reverse effect on intake. The more supplements the patient receives, the less likely the individual is to eat them.

Food is not always the source of a patient's intake problems; these could instead be related to the act of eating. Upper extremity capabilities must be present to feed. If the patient has any upper extremity disabilities, independent feeding may be an issue.

Oral capacity also affects food intake, including in patients who may have the appetite to eat. Difficulty chewing food can result from a number of problems, including ill-fitting dentures, missing teeth, poor dental hygiene, oral infections, and discomfort following an oral procedure. Changes in food consistency are prudent in these situations, but only when they have been discussed with the patient.

Medication Issues

Medications cannot be overlooked when patients are not eating well. They affect intake in a variety of ways and, with prolonged use, eventually cause changes in nutritional status. Some drugs are secreted into saliva, causing an unpleasant taste. Some are unpalatable (eg, potassium preparations, cholestyramine), and some may cause a taste disorder by altering receptor function (eg, captopril, penicillamine). Facilitating relief by masking the drug's taste with food should be considered. Some examples of drugs and their possible side effects include the following:

  • Phenytoin - Gingival hyperplasia

  • Antineoplastic agents - Delayed wound healing and microbial infections

  • Broad-spectrum antibiotics - Candidiasis

  • Anticoagulants - Bleeding gums

Prolonged use of antihistamines and bronchodilators may decrease olfactory receptor response. Additionally, medications may alter the oral environment and result in decreased intake. For example, antidepressants may cause dry mouth and broad-spectrum antibiotics may lead to candidiasis. Consider decreasing dry, salty foods; offer moist, soft foods. Liquids should be increased at meal times, and spicy and acidic foods should be avoided.

Any medication taken orally can potentially cause gastric irritation (eg, nonsteroidal anti-inflammatory drugs [NSAIDs]). Drugs may stimulate or depress the appetite. Appetite stimulants include antihistamines and psychotropic drugs. The antineoplastic drug megestrol acetate often is prescribed to stimulate appetite. Numerous drugs have the secondary effect of decreasing appetite. These agents include dextroamphetamine and methylphenidate.

Antineoplastic agents, levodopa, and sulfasalazine are a few drugs that may cause disagreeable symptoms (eg, nausea, vomiting). Digitalis derivatives can stimulate chemoreceptor triggers directly and initiate vomiting. Suggestions include offering small quantities of foods that are easily digestible, serving carbonated liquids as the patient requests, maintaining adequate hydration, offering cold foods instead of hot foods (if the aroma of hot foods causes problems), and avoiding fried, greasy foods.


The main offenders include anticholinergics, sedatives, hypnotics, and narcotics. To aid relief, adequate hydration should be maintained, daily fiber intake should be increased, and dependency on laxatives should be avoided.


Cancer chemotherapeutic agents, antibiotics, laxatives, and antacids have the potential to cause diarrhea. To aid relief, a bland diet should be provided in small amounts, and the following should be avoided:

  • Caffeine

  • Highly spiced foods

  • Concentrated sweets

  • Uncooked fruits and vegetables

  • Whole grain breads and cereals

Eating Environment

Although a patient's dining environment is probably the easiest problem to solve, it is the issue that is the most likely to be overlooked. If the patient dines at his or her bedside, the clinician should assess the surroundings.


Clutter on the bedside tray makes eating an unpleasant and difficult experience. Care needs to be taken to make sure the patient's bedside tray table is clear of extraneous items (eg, urinals, tissues, newspapers, magazines). The dining experience should be made into one that can be enjoyed.


Proper lighting should be emphasized. Open the patient's curtains. Turn on the lights. Let the patient see what he or she is going to eat.


Eating from a bed is very difficult. An easy solution is to transfer the patient to a chair for meals if possible. Perhaps the tray table does not adjust to proper height for the chair or bed. A quick adjustment to the level of the bedside table can make all the difference in the world.


Comfort is the key. Patients need to be relaxed, and proper positioning improves the comfort level. Increased comfort creates an increased ability to sit up and eat; optimally, this means increased oral intake.

Room Occupancy

Arguments have been made for privacy and for company when it comes to pleasurable dining. The ideal environment should be discussed with the patient, and attempts should be made to accommodate dining wishes. If a roommate is acceptable but the roommate has a medical condition that prevents quality dining, such as a persistent cough, vomiting, diarrhea, or flatulence, consider an adjustment of the meal location.

With cafeteria-style dining, the same issues are present. The cafeteria needs to be clean, to have adequate lighting and comfortable chairs, and to be wheelchair accessible. Again, table assignments need to be discussed. If patients are not comfortable with their dinner company, their intake will suffer. Encourage family members to visit at mealtime, perhaps bringing in a favorite dish or dessert.

The dietitian should make daily meal rounds. This type of direct observation provides significant information and often provides clues as to why a patient may not be eating.

Enteral Nutrition

When the patient is unable to consume adequate nutrition orally, more aggressive support needs to be considered. Going back to the saying, "If the gut works, use it," enteral support is an alternate route of intervention. [7]

A patient with a functional GI tract is a candidate for enteral support when he or she will not, should not, or cannot take nutrition orally. The benefits of enteral support include the following:

  • Maintenance of GI structure/integrity

  • Improved utilization of nutrients

  • Cost effectiveness

  • Ease of administration

  • Lowering of hypermetabolic response

The feeding route is the first consideration in enteral support (see Table 8). This decision is based on the duration of feeding, the patient's medical status, and the risk of aspiration. Short-term feeding is considered to be less than 6 weeks, and long-term feeding is greater than 6 weeks.

Table 8. Enteral Feeding Routes (Open Table in a new window)

Enteral Access





Requires intact gag reflex, normal gastric

motility/gastric outlet

Low cost,

easy placement,

easy removal

Increased risk of





High aspiration risk,

delayed gastric emptying,


gastric dysfunction resulting from trauma or surgery

Beneficial for

lower incidence

of nosocomial


Requires endoscopy

or fluoroscopy for

placement, increased risk of tube



Normal gastric functions and no esophageal reflux,

or when nasal

route is unavailable

Optimal patient


can be placed

via endoscopy,

laparoscopy, or


Increased risk of


after tube removed;

stoma care required;

potential for tube



Impaired gastric motility,

GERD/aspiration potential,

gastric dysfunction

resulting from trauma or surgery


aspiration risk;

can be placed

via endoscopy,

fluoroscopy, or laparoscopy

Potential for




Continuous/Bolus Feedings

Feedings may be continuous or bolus. Continuous feeding is a more reliable route of nutrient delivery, as a feeding pump is required. Feedings are given over 16-24 hours. This method has been associated with lower residual volumes, a decreased incidence of diarrhea, and a decreased risk of aspiration. Continuous feeding is recommended at the initiation of enteral support, as it is much better tolerated than a bolus infusion. As the small bowel tends to be sensitive to large volumes, the continuous feeding method is recommended when feeding postpylorically.

Bolus infusions via gravity or syringe generally are used in the medically stable patient, as well as in the homebound or rehabilitation patient. Feedings are given quickly (2 cans over 30 minutes, 4-6 times per day), mimicking a regular meal. The maximum amount recommended is 400-500 mL per feeding; however, 250-400 mL is the most common infusion amount. Establish tolerance with continuous feeding, and then transition to bolus feedings when tolerance has been established.

Initiation and Advancement Schedule

Prior to the initiation of tube feeding, placement of the nasogastric feeding tube must be verified. Radiographic confirmation is the most reliable method of determining placement. Use of a promotility agent (unless contraindicated) before insertion increases the chances of transpyloric placement, which is better tolerated initially. The following agents are recommended 30 minutes before placement:

  • Metoclopramide - 20 mg IV

  • Erythromycin - 200-400 mg IV

No standard initiation/advancement schedules appear in the literature; however, reasonable schedules can be recommended based on the type of feeding formula, location of the feeding, the type of patient, and the patient's condition. Examples include the following:

  • Isotonic formula/gastric feedings can be initiated full strength at a rate of 20-25 mL/hr and advanced every 8 hours in increments of 20-25 mL until the desired rate is achieved.

  • Hypertonic formula/small bowel feedings should be initiated full strength at 10-15 mL/hr and increased every 12 hours in increments of 10-15 mL until the desired rate is achieved.

Tube feeding initiation should also be based on the type of patient.

  • Hypometabolic

    • This individual is seen as a marasmic type of patient, unstressed and clinically starved.

    • Such patients are at risk of developing refeeding syndrome. Refeeding syndrome is an electrolyte disturbance that accompanies an overzealous nutrition regimen. It can lead to death if left untreated.

    • Nutrition support should be cautious, with an aim to rebuild.

    • The initiation rate should be low, and the advancement schedule should be conservative. It may take several days to achieve the target.

  • Hypermetabolic

    • This individual is seen as a patient of the kwashiorkor type, is clinically stressed from injury/trauma, and is considered catabolic.

    • Such patients are at risk of overfeeding.

    • Nutritional support should be aggressive but not excessive.

    • Targets need to be achieved in a timely manner, since the patient is in need of optimal nutrition to deal with a hypercatabolic situation.

Initial infusion rates and the subsequent advancement schedule also depend on the overall condition of the patient, as follows:

  • Altered mental status - Initiate and advance feeding slowly because of an increased risk of aspiration.

  • Recent use of GI tract - Prolonged nonuse of the GI tract requires cautious initiation and advancement schedules.

  • Nutritional status - The feeding schedule can be more aggressive with patients of normal nutritional status.

  • Functional status of GI tract - Assess partial versus full function; if the gut works a little, use it a little.

All hospitals have an enteral formulary. Physicians should obtain a formulary card to help make product decisions. Several formula categories should be considered when selecting a product for enteral nutrition support.


Complications associated with enteral support are largely preventable through formula selection, proper administration, and careful monitoring. Complications fall into gastrointestinal, mechanical, and metabolic categories, as follows [8] :

  • Gastrointestinal complications

    • Diarrhea is the most common complication of enteral feeding. [9] Diarrhea is defined as 4 bowel movements per day or a large liquid stool (>250 g). The most common causes of diarrhea associated with enteral support include the following:

      • Medication - This is mainly related to antibiotics, antacids, potassium supplementations, cimetidine, sorbitol-containing medications, or medications in the form of an elixir.

      • Hypoalbuminemia - An albumin level of less than 2.5 g/dL results in decreased colloidal osmotic pressure with accompanying peripheral edema.

      • Malabsorption

      • Bacterial contamination

      • Lactose intolerance

      • Lack of fiber

      • Altered bacterial flora

      • Rapid administration

    • Constipation is defined as no stools for 3 or more days and is less common in the acute care setting. Possible causes include the following:

      • Dehydration

      • Lack of fiber

      • Dysmotility and GI obstruction

    • Nausea/vomiting - If vomiting occurs, tube feeding should be discontinued to prevent possible aspiration. Aspiration is the most serious complication of enteral support. If undetected, aspiration may become life threatening. Potential causes include the following:

      • Delayed gastric emptying

      • Neurologic impairment

      • Decreased intestinal motility

      • Presence of a nasoenteric tube and tube migration

      • Nausea and/or vomiting can be prevented with the following techniques:

      • -

        Using a small bore feeding tube (< 10 French).

      • -

        Elevating the head of the bed 30° during feeding.

      • -

        Having the patient ambulate whenever possible.

      • -

        Monitoring for tube migration.

      • -

        Positioning the tube postpylorically.

      • -

        Recommending a continuous administration schedule versus bolus feeding.

      • -

        Positioning the patient on the right side to facilitate passage of the gastric contents through the pylorus.

      • -

        Having the patient use promotility agents 30 minutes before eating.

      • -

        Checking residual volumes periodically. No consensus has been reached concerning acceptable gastric residuals; however, if a residual volume is greater than 200 mL with a nasogastric tube or greater than 100 mL with a gastrostomy tube, it would be prudent to delay the feeding.

  • Mechanical complications result from placement of the feeding tube, from the presence of a feeding tube, or when a tube becomes blocked.

  • Metabolic complications involve changes in laboratory values, fluid status, and/or clinical conditions.

Table 9. Metabolic Complications of Enteral Support (Open Table in a new window)


Possible Cause

Prevention or Therapy



Diabetes mellitus,

sepsis, trauma,

metabolic stress,

refeeding syndrome

Goal is glucose < 200 mg/dL.

Control w/oral hypoglycemic

agents, insulin, or a change in

tube-feeding formula.


Inadequate fluid intake, excessive fluid losses,

use of hypertonic or high-protein formula

Calculate free-water needs.

Provide adequate free water based on tube-feeding formula.


Excessive fluid intake;

cardiac, hepatic, or

renal failure; refeeding


Calculate free-water needs.

Use a more concentrated formula if necessary.


Refeeding syndrome,

diuretic therapy, excessive

losses from diarrhea,

insulin therapy

Provide supplemental K+ to replete. Do not advance

rate of tube feeding until



Refeeding syndrome,

insulin therapy,

phosphate-binding antacids

Provide supplemental phosphorus for repletion.

Do not advance rate of tube feeding

until corrected. Adjust antacid dosage if needed.


Dilutional state,

hyperglycemia, cardiac,

hepatic, or renal


Calculate free-water needs.

Use a more concentrated formula if necessary.


Renal failure, excessive

potassium in tube-feeding formula

Adjust tube-feeding formula.


Inadequate fluid

Calculate free-water needs.

Use a standard formula or a less concentrated formula if necessary.

Transition From Enteral to Oral Feeding

The goal of rehabilitation is to return the patient to normal function. Return to normal function is the goal of nutritional management as well. The goal with enteral support is a gradual transition from tube feeding back to an oral diet, if that is a possibility. The following options are suggested to accomplish an effective transition without compromising the patient's nutritional status:

  • Never discontinue the tube feeding all at once. If the patient is on 100% enteral support, resume oral diet without adjusting tube feeding.

  • Monitor oral calorie/protein intake initially and then on a periodic basis to determine the percentage of calories/protein being met by the oral diet. Decrease tube feeding to meet the patient's needs. For example, if the patient is consuming 50% of his or her needs orally, cut the tube feeding in half.

  • Tube feed nocturnally, allowing the patient time away from tube feeding during the day in hopes of producing an appetite.

  • Continue calorie counts and decrease time of enteral infusion as appropriate.

  • Do not be impatient. If patient intake remains poor and he or she complains of not being hungry secondary to tube feeding, turn it off for 24 hours. Do not pull the feeding tube. Complete calorie count during that time to see if intake increases without nocturnal support. If intake improves to more than 75% of needs, one can feel confident that the patient will progress nutritionally. If intake fails to improve, it is unlikely that the tube feeding is causing inadequate intake. At this point, incremental goals need to be established with the patient in an effort to motivate the patient toward tube-free nutrition.

In a study by Ikenaga et al of stroke patients with dysphagia who were on enteral feeding in a convalescent rehabilitation ward setting, several factors were associated with the likelihood of transitioning to complete oral intake by the time of discharge. According to the investigators, these included the following [10] :

  • Younger age
  • Initial stroke
  • Greater Functional Oral Intake Scale score
  • Greater Functional Independence Measure cognitive score
  • Greater BMI
  • Shorter period in the acute care ward

Parenteral Nutrition

This type of nutritional support is indicated for patients with a nonfunctioning GI tract and an inability to tolerate oral or enteral nutrition. As with enteral nutrition, duration of support is the decision between the 2 available routes (peripheral parenteral nutrition [PPN] and central or total parenteral nutrition [TPN]). PPN is considered to be a short-term/adjunct intervention. A time frame of less than 14 days is recommended, as PPN is used for transitional therapy when the patient's oral intake is improving but still is inadequate to support his or her nutritional needs or when tube feeding is only partially successful. TPN is intended for full nutritional support and is recommended for a minimum of 7 days for improvement in patient outcome to occur.

Access for aggressive nutritional support is dependent on the duration of therapy, as discussed above, as well as the patient's medical condition, energy requirements, and fluid tolerance.

Peripheral access may be obtained by nonsurgical staff using a standard venipuncture method. The patient must have adequate peripheral veins and be able to tolerate hypertonic solutions, as PPN solutions are generally 600-900 mOsm/L. Peripheral access is hard to maintain; hence, the 2-week limit is enforced.

Central access is determined by the expected duration of nutritional support. Short-term access is available using single-, double-, or triple-lumen catheters. The tip of the central catheter is positioned in the superior vena cava. Peripherally inserted central catheter (PICC) lines can be placed by a trained nurse and do not require a surgical procedure. The line is placed in the antecubital vein and threaded into the subclavian vein.

Single-, double-, or triple-lumen catheters are also available for long-term access. The catheter is placed surgically and tunneled subcutaneously away from the insertion site. The exit site is in the chest wall. PICC lines may be used for long-term access as well.

Unlike enteral support, parenteral nutrition should be infused continuously over a 12-24 hour period. Cyclic infusion rates are reserved for the more stable patient or the patient who is likely to be discharged on TPN.

Since PPN is restricted to a maximum of 10% dextrose (5% final concentration), patients can tolerate initiation of the infusion at the target rate. TPN, with its higher concentrations of dextrose, requires an advancement schedule. Skipper's recommendations for initial parenteral infusion rates for the first 48 hours of infusion are outlined in the following list [11] :

  • First 24 hours

    • Volume should be based on patient tolerance. If fluid tolerance is unknown, begin with 1 liter or less.

    • Carbohydrate - Dextrose can be concentrated maximally into 1 liter if glucose control is acceptable. With hyperglycemia, diabetes, or refeeding syndrome, begin with a 10-15% dextrose solution.

    • Protein - Maximum protein (ie, 60-70 g) usually can be given.

    • Lipid - Administer lipids during this period if baseline triglycerides are less than 400 mg/dL.

    • Electrolyte/mineral - Adjust the level as needed; replete deficiencies.

  • 24-48 hours

    • For most patients, the target rate can be achieved by the second day.

    • Volume - Increase the volume to the goal per fluid tolerance.

    • Carbohydrate - Advance to the goal if glucose is less than 200 mg/dL.

    • Protein - If volume is not an issue, advance to the goal.

    • Lipid - Maintain triglycerides at less than 400 mg/dL during continuous feeds and at less than 250 mg/dL 4 hours after infusion.

    • Electrolytes/minerals - Adjust the level as needed; replete deficiencies.

  • Formula selection

    • Nonprotein calorie (NPC) sources are made up of 2 macronutrient groups (ie, carbohydrates [CHO], lipids).

    • The following (Table 10) is a summary of recommendations for infusion and general information:

Table 10. Summary of Recommendations for Infusion (Open Table in a new window)




Standard distribution

70-85% NPC

15-130% NPC

Maximum infusion

7 mg/kg/min 2.5 g fat/kg/d

(60% NPC)

Recommended infusion

< 5 mg/kg/min

< 1.0 g fat/kg/d


3.4 kcal/g

9.0 kcal/g

Available concentrations


10% and 20%

The optimal infusion schedule is not less than 12 hours.

Dextrose is the carbohydrate source, as well as the major source of nonprotein calories (NPC) in parenteral nutrition. The carbohydrate load provided should be adequate to spare protein for wound healing/metabolic demands without exceeding patient tolerance (hyperglycemia).

Table 11. Summary of the Various Dextrose Concentrations (Open Table in a new window)


Grams Carbohydrate






Very poor Db control




Very poor Db control




Db in fair control




Considered a standard with no fluid issues




Considered a standard with mild fluid

restriction and possible lipid issues




Increased needs with moderate fluid restriction




Maximally concentrated, excessive nutritional demands

Intravenous lipid infusions are necessary as a source of essential fatty acids. They are also a concentrated source of NPC. The calories yielded depend on the concentration of the lipid emulsion used. Examples of lipid emulsions and their calories yielded are 10% lipid (1.1 kcal/cc) and 20% lipid (2 kcal/cc). Lipid infusion schedules vary by institution and can range from twice a week to daily. Lipids are made up of egg phospholipid. Therefore, patients with an egg allergy may not tolerate lipid infusions.

Table 12. Common TPN Schedules (500 cc) (Open Table in a new window)

% Lipid



Weekly Average





























NB: When using a 3-in-1 TPN, the lipids are added to the TPN daily.

The role of protein in TPN is to maintain nitrogen balance, inhibiting the breakdown of skeletal muscle. The amount of protein necessary is based on a patient's metabolic needs, as discussed earlier. Note that an amount below 0.5 g protein/kg does not promote positive nitrogen balance. In a healthy population, protein should be provided as 11-20% of total kcal. In a stressed population, 40% of total kcal is common. Protein in TPN is in the form of crystalline amino acids that provide 4 kcal/g. All amino acid mixtures contain intrinsic electrolytes. The physician needs to contact the pharmacy service if specialized electrolytes are necessary.

Table 13. An Example of the Intrinsic Electrolytes in Some Common Amino Acid Formulations (Open Table in a new window)


10% FreAmine

15% Aminosyn

6.9% HBC

Sodium (mEq/L)




Phosphate (mmol/L)




Acetate (mEq/L)




When a standard electrolyte formula is ordered, it is made up of the intrinsic electrolytes with a Hyperlyte mixture added. The following section on electrolytes further discusses this issue.

The electrolyte composition in parenteral nutrition is designed to maintain normal body function. Customized electrolytes are an option based on the patient's underlying disease process/stressful situations. The available commercial preparations are intended to meet normal range requirements. Table 13 summarizes these requirements and standard amounts of electrolytes.

TPN can affect the metabolic acid/base imbalance. Therefore, the chloride and acetate in the TPN can be adjusted. For a metabolic acidosis, the maximum acetate should be used. For a metabolic alkalosis, the maximum chloride should be employed.

Table 14. Requirements and Standard Amounts of Electrolytes (Open Table in a new window)


24-Hour Requirement Standard/L TPN

Phosphorus (mmol)



Potassium (mEq)



Magnesium (mEq)



Sodium (mEq/L)



Calcium (mEq)



Chloride (mEq)



Acetate (mEq)



Parenteral supplementation is based on recommendations from the American Medical Association Nutrition Advisory Group.

The daily parenteral requirements for vitamins and minerals for adults are as follows:

  • Thiamine - 3 mg

  • Riboflavin - 3.6 mg

  • Niacin - 40 mg

  • Folic acid - 400 mc g

  • Pantothenic acid - 15 mg

  • Pyridoxine - 4 mg

  • Cyanocobalamin - 5 mcg

  • Biotin - 60 mcg

  • Ascorbic acid - 100 mg

  • Vitamin A - 3300 IU

  • Vitamin D - 200 IU

  • Vitamin E - 10 IU

  • Chromium - 10-15 mcg

  • Copper - 0.3-0.5 mg

  • Manganese - 60-100 mcg

  • Zinc - 2.5-5 mg

Complications From Parenteral Nutrition

Parenteral nutrition support has a lengthy list of potential metabolic complications, which is the reasoning behind the judicious monitoring of nutrition support teams. Table 15 provides a listing of the metabolic complications.

Table 15. Metabolic Complications from Parenteral Nutrition (PN) (Open Table in a new window)


Suspected Cause

Suggested Treatment


  • Glucose load exceeds endogenous insulin secretions

  • Rapid infusion of dextrose

  • Steroid treatment

  • Underlying disease states: pancreatitis, sepsis,

  • diabetes, trauma, surgery

  • Advance rate slowly

  • Do not increase rate until hyperglycemia

  • is controlled

  • Add insulin to PN

  • Provide fewer carbohydrate calories and increase lipid calories


  • Abrupt discontinuation of

  • dextrose solution

  • Insulin in PN exceeds

  • requirements

  • Treat hypoglycemia with IV

  • bolus infusion of d50

  • Avoid sudden cessation of PN

  • If PN is discontinued suddenly, d10

  • fluid replacement at same rate

  • Monitor glucose levels

  • Adjust insulin accordingly


  • Decreased renal function

  • Metabolic acidosis

  • Excessive K+ in PN

  • Low cardiac output, tissue necrosis, and systemic sepsis

  • K + - sparing medications

  • Discontinue PN

  • Provide d10 replacement at same rate

  • Provide sodium bicarbonate

  • Adjust electrolyte mixture to

  • decrease K+

  • Monitor lab panels closely

  • Adjust PN as needed

  • Assess for K + - sparing medications


  • Potassium loss from diuresis, diarrhea, steroid treatment, K+ -wasting medications

  • Increase amount of K+ in PN

  • Peripherally replete K+


  • Dehydration from fever, inadequate free water,

  • diuresis, ADH deficiency, and head trauma

  • Provide hydration with d5


(True sodium depletion)

  • Sodium loss from diuretic

  • treatment, diarrhea,

  • and adrenal insufficiency

  • Increase Na+ in PN

  • Consider IV using normal saline



  • Extracellular fluid overload:

  • CHF, renal failure, edema, liver disease/cirrhosis

  • Discontinue any additional

  • IV fluids

  • Increase dextrose

  • concentrations


  • Excessive phosphorus in PN

  • Renal insufficiency

  • Decrease amount of phosphorus

  • in PN

  • Consider the phosphorus

  • in lipids, emulsions, and phosphate binders


  • Inadequate phosphorus in PN

  • Increased phosphorus needed during

  • anabolism/protein synthesis

  • Refeeding syndrome

  • Increase amount of phosphorus in PN

  • Replete phosphorus peripherally

  • before advancing rate of

  • infusion

  • Increase phosphorus in PN




  • Inability to clear lipids from bloodstream

  • Sepsis

  • Multisystem organ failure

  • Hyperlipidemia


  • Decrease lipid volume

  • Lengthen lipid infusion



  • Excessive protein provided

  • Dehydration

  • Inadequate

  • NPC provided

  • Decrease protein load

  • Increase fluids provided

  • Increase NPC provided

Abnormal liver function tests

  • Excessive glucose or

  • lipid load

  • Ensure patient is not

  • being overfed


  • Excessive protein and NPC provided

  • Decrease protein and NPC

Consequences of protein calorie overfeeding are as follows:

  • Carbohydrates - >5 mg/kg/min

    • Lungs

      • Increased CO2 production

      • Possible respiratory failure in patients with limited pulmonary reserve and prolonged mechanical ventilation

    • Hyperglycemia - >220 mg/dL

    • Hyperinsulinemia

      • Impaired phagocytosis and neutrophil chemotaxis

      • Increased intracellular transport of K+ and phosphorus

    • Liver

      • Fatty liver infiltration

      • Increased serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, and alkaline phosphatase

      • Hepatomegaly

      • Cholestasis

  • Fat - >2 g fat/kg/d

    • Increased serum triglyceride clearance impaired

  • Protein - >2 g protein/kg/d

    • Decreased renal function

    • Ureagenesis

Transition From Parenteral to Enteral to Oral Nutrition

As with enteral support, the goal with parenteral support is a gradual transition back to tube feeding or oral nutrition. [12] Treatment options have been developed to make the transition effective without compromising the patient's nutritional status. Recommendations for this transition include the following:

  • Never discontinue TPN all at once, as it could cause a rebound hypoglycemia. Tapering down is recommended. The taper down should be based on the adequacy of the patient's tube feeding or oral intake.

  • If the patient is on tube feeding, increase the rate of the tube feeding while decreasing the rate of the TPN. Combination rates should meet both protein and calorie needs.

  • If the patient is on an oral diet, calorie counts are recommended. If the patient is able to consume 50% of his or her needs orally, consider changing TPN to a cyclic infusion. Discontinue the TPN during the day and provide 50% of the patient's nutrition over 10-12 hours during the night. Tube feed nocturnally, allowing the patient time during the day away from tube feeding in hopes of producing an appetite.

  • Continue calorie counts and decrease time/amount of parenteral infusion as appropriate.


Nutrition for Specific Disease States

Pressure Ulcers

Patients who are at the greatest risk of developing pressure ulcers are those who are nonambulatory and have a compromised nutritional status. Disease states, such as cancer, diabetes, renal disease, and heart disease, may predispose patients to pressure ulcers secondary to the decrease in oxygen supplied to at-risk areas (eg, coccyx, elbows, heels).

Assessment of serum albumin is key in this high-risk population, since hypoalbuminemia, if not corrected, has been associated with the development and progression of pressure ulcers. Nutritional intervention needs to include adequate protein and adequate calories to spare protein from wound healing. The goal is a serum albumin of greater than 3.5 g/dL. The amount of protein and number of calories need to increase as the stage of the ulcer increases. Supplementation with vitamin C should not exceed 200% of the US recommended daily allowance (RDA). Supplementation with zinc is consistent at 30 mg/day for men and 24 mg/day for women.

Neurologic Diseases

Not all patients with neurologic conditions have the same feeding problems; however, a common problem throughout this population is dysphagia, or difficulty swallowing. [1, 13] Observable symptoms that dysphagia may be present include drooling, choking, coughing (during or after meals), an absent gag reflex, and a gurgly voice quality. If undiagnosed, dysphagia can lead to malnutrition as a result of inadequate intake.

Early detection and intervention are paramount. Nutritional intervention is performed with a team approach that centers primarily on the dietitian and the speech therapist. The speech therapist identifies treatment options; the dietitian adjusts diet consistency (liquids vs solids) to meet a patient's needs and ensures that palatability is not jeopardized in the process.

Another common issue is a patient's limited ability to eat independently, as a result of problems such as hemiparesis, tremors, apraxia, and weakness. The associated medical concern is an increased risk of aspiration. To prevent aspiration, the best position for the patient is sitting upright as erect as possible, with both feet resting on the floor. Independence in self-feeding can be achieved with the use of a scoop plate if the patient has the strength to push food to the side of the plate. The plate is designed to allow food then to fall on the spoon.

Enteral nutrition is a treatment option for this population when oral nutrition has been deemed unsafe due to aspiration risk or when the patient can no longer meet nutritional needs with an oral diet.

A study by Wills et al found that in patients with amyotrophic lateral sclerosis undergoing enteral feeding, there were fewer adverse events in those who received a high-carbohydrate hypercaloric diet (8 patients; 23 adverse events) than in those who received a high-fat hypercaloric diet (6 patients; 48 adverse events) or an isocaloric diet (6 patients; 42 adverse events). [14]

Traumatic Brain Injury

Most patients with traumatic brain injuries (TBIs) are well nourished prior to their injury; however, they become hypermetabolic and catabolic following injury. Therefore, aggressive nutritional intervention needs to be addressed very early. Patients who are not treated aggressively are likely to undergo rapid loss of lean body mass and immunosuppression.

Energy requirements for patients who have sustained TBI generally are 40% greater than those estimated by the Harris-Benedict equation. Therefore, indirect calorimetry is recommended. Providing adequate protein is essential, but note that patients following TBI are likely to be in a negative nitrogen balance for the first 2-3 weeks postinjury, despite aggressive intervention.

In general, a large percent of this population experience dysphagia, impaired gastric emptying, and alterations in normal eating patterns. Some patients are distracted easily, and meal times need to be extended. Some eat very rapidly and tend to consume excess quantities at meal times. Close monitoring during meals is essential. Parenteral and/or enteral support often is a necessary intervention during the early stages of treatment and during the transition period back to oral nutrition.

A prospective, observational study by Horn et al indicated that in patients with TBI who are undergoing inpatient rehabilitation, those with a propensity score of over 40% for the likely use of enteral nutrition may benefit from the administration of enteral nutrition, particularly with a high-protein formula, for at least 25% of their rehabilitation stay. In such patients who received this treatment, the study found, the Functional Independence Measure motor and cognitive scores were higher at rehabilitation discharge than they were for matched patients. [15]


Nutritional support in this population is a challenge. These patients are at extraordinary risk of infection and intestinal ileus. Patients with burns are hypermetabolic and catabolic. Energy needs can increase by 100%, related to hypermetabolism. Protein needs are huge owing to the catabolic condition and because of protein losses through the wound itself.

Patients with burns over less than 20% of their total body surface area (TBSA) usually are able to meet nutritional needs with a high protein/calorie diet. Patients with burns over greater than 20% of their TBSA require a more aggressive approach, such as TPN and/or tube feeding. If an ileus is present or the patient is unable to tolerate 100% of his or her nutritional needs enterally, TPN is the intervention of choice.

Spinal Cord Injury

Nutrition in acute SCI is a very complex issue. The following complications are associated with SCI and can affect the patient's ability to consume adequate nutrition:

  • Paralysis

  • Glucose intolerance

  • Anemia

  • Paralytic ileus

  • Gastrointestinal ulcers

  • Neurogenic bowel and bladder

  • Depression

  • Skin/wound breakdown

  • Pneumonia

Nutritional needs change frequently with this population because of stress response, sepsis, fever, infection, and surgery. Nutritional assessments need to be frequent, with ongoing diet alterations made to keep up with the patients' changing needs.

Pulmonary Disease

The major function of the respiratory system is to provide adequate oxygen to the body and to eliminate the carbon dioxide this process produces. The 3 macronutrients (ie, carbohydrate, fat, protein) all affect this ratio. The respiratory quotient (RQ) is a volume ratio between the oxygen consumed and carbon dioxide produced. The following are the RQs associated with each macronutrient substrate:

  • Substrate RQ

    • Carbohydrate 1.0

    • Lipid 0.7

    • Protein 0.8

    • Overfeeding >1.0

Overall energy needs and protein needs are based on the patient's goal to maintain lean body mass versus repleting lean body mass. In the situation of maintenance, energy needs are estimated at 25-35 kcal/kg, and protein needs are estimated at 1.2-1.9 g protein/kg. In the situation of repletion, energy needs are estimated at 35-45 kcal/kg and protein needs are estimated at 1.6-2.5 g protein/kg.