Download TPN-I-Nutritional Assessment

Professor T. Najjar
PHCL-474 (TPN)
Dept of clinical pharmacy
Total Parenteral Nutrition
Chapter II
Part I: Introduction
__________________________________________________________________________________
Malnutrition
Definition:

Malnutrition occurs when there is a deficiency of any nutrient resulting from
abnormalities in the intake, digestion, absorption, metabolism, and/or excretion of the
nutrient.

A more clinically useful definition of malnutrition is the state induced by alterations
in dietary intake resulting in changes in subcellular, cellular, and/or organ function
that exposes the individual to increased risks of morbidity and mortality and can be
reversed by adequate nutrition support.

The incidence of malnutrition among hospitalized patients has been reported to be as
high as 50%.

Because in the hospitalized patient, acute malnutrition occurs when nutrient intake is
inadequate in the face of injury or stress (e.g., trauma, infection, major surgery), and
nutrient stores are rapidly depleted as a result. Acute stress or injury increases energy
needs to repair tissues. When this energy is not provided exogenously, the body turns
to endogenous sources of energy by breaking down skeletal muscle to release amino
acids for the production of glucose (protein malnutrition).

This iatrogenic malnutrition can occur rapidly even in individuals who were well
nourished before hospitalization. Once the illness or injury improves, this acute
malnutrition resolves.

In contrast, starvation or semistarvation states, without stress or injury, allow humans
to slowly adapt to inadequate nutrient intake. This adaptation results in the use of
endogenous fat stores for energy and a slow loss of muscle proteins (energy
malnutrition).

Nevertheless, energy and protein stores are not unlimited and with total starvation,
death occurs in normal weight individuals in about 60 to 70 days.

Clearly, the patient with a history of chronic malnutrition who is faced with stress or
injury is at the greatest risk of developing malnutrition.

Protein-calorie (mixed) malnutrition is the most common type of nutritional
deficiency in hospitalized patients and is manifested by depletion of both tissue
energy stores and body proteins.
1
Professor T. Najjar

PHCL-474 (TPN)
Dept of clinical pharmacy
Malnourished patients have prolonged hospitalizations and are at a higher risk of
developing complications during therapy.

The complications are the result of organ wasting and functional impairment and
includes: Weakness, decreased wound healing, altered hepatic metabolism of drugs,
increased respiratory failure, decreased cardiac contractility, and infections such as
pneumonia and abscesses.
Specialized nutrition support

Hospitalized patients with severely inadequate intake for 7 days or longer or those
with a weight loss of 10% of their preillness weight are considered malnourished or at
risk of developing malnutrition.

Nutritional intervention should be considered for these patients: Patients who cannot
meet their nutritional needs by eating enough food by mouth should be considered for
some type of specialized nutrition support.

Specialized nutrition support provides specially formulated and/or delivered
parenteral or enteral nutrients.

For those who cannot eat by mouth but who have a functional GI tract, a method of
enteral nutrition or tube feeding should be considered.

When possible, the GI tract should be used for providing nutrients. Nutrients
administered enterally may be more beneficial and less expensive than those provided
by the parenteral route.

Stimulation of the intestine with enteral nutrients maintains mucosal barrier structure
and function and has been associated with decreased infectious morbidity in critically
ill patients compared with those receiving nutrients parenterally.

For these reasons, total parenteral nutrition is reserved only for patients: 1) whose GI
tracts should not be used or cannot be used and 2) those patients whose GI tracts do
not absorb enough nutrients to maintain adequate nutritional status.
II)
PATIENT ASSESSMENT

Assessment of a patient's nutritional status allows analysis of body composition and
evaluation of physiologic function.

Such an assessment is important in determining the presence and severity of
malnutrition or the risk of developing malnutrition, and thus determines the need for
specialized nutrition support and whether the goal of therapy is to maintain current
nutritional status or to replete fat and lean body mass.

Assessment should include evaluation of multiple factors and not rely on one
2
Professor T. Najjar
PHCL-474 (TPN)
Dept of clinical pharmacy
parameter.

The factors includes: nutritional history including (body weight), physical exams,
anthropometrics, and biochemical indices.
Nutritional History

A nutritional history is critical in assessing nutritional status. Information can be
obtained by interviewing the patient or the patient's family and reviewing the medical
record to identify factors that may contribute to malnutrition, or increase the risk of
developing malnutrition."

Multiple factors can contribute to the development of malnutrition.

For example, a patient who is elderly, lives alone on a fixed income, takes multiple
medications, has 'a history of multiple intestinal surgeries for peptic ulcer disease
(PUD), and is hospitalized and receiving nothing by mouth (NPO) until return of GI
function after another surgery for resection of the small intestine has multiple risk
factors for malnutrition.

Medications also can adversely affect nutritional status by decreasing synthesis of
nutrients, decreasing food intake by altering appetite and taste, altering absorption or
metabolism of nutrients, or increasing nutrient requirements.

A nutritional history also should include evaluation of body' weight.

The components of a nutritional history are in the following list:
Weight History.

Weight and weight history are important in evaluating nutritional status. Weight loss
is a sign of: 1) negative energy and 2) negative protein balance and is associated with
poor outcome of hospitalized patients.

A weight loss of >10% is considered significant for malnutrition.

If weight has been lost, it must be investigated further to determine: 1) whether the
loss is intentional and 2) whether the weight loss is continuing or has stabilized. A
patient's current weight often is compared with a standard such as insurance tables for
"ideal body weight"

The percentage of ideal body weight (IBW) is determined as shown in this equation
% of I BW = (Current weight/IBW) (100) 35-1.

This method of assessing weight has its shortcomings because the patient's weight is
compared with a population standard rather than using the individual patient as the
reference point.

For example, a patient who is significantly overweight and has lost large amounts of
3
Professor T. Najjar
PHCL-474 (TPN)
Dept of clinical pharmacy
weight may still be >100% of IBW and therefore not considered at risk for
developing malnutrition.

A more patient-specific method of evaluating weight is to compare current weight
with the patient's usual or preillness weight. This can be determined using the
following equation.
% Usual body weight = ( Current weight / Usual body weight) (100) 35-2

Using this method, the obese patient that has lost weight may be determined to be
<90% of usual weight (weight loss of > 10%) and therefore at risk for malnutrition.

It also is important to assess over what time period the change has occurred. Weight
loss is considered severe if loss exceeds 2% in I week, 5% in I month, or 10% in 6
months.

The pattern of weight loss must be evaluated to determine whether the loss is
continuing or stabilizing or whether the patient is regaining some weight.

Continuing weight loss is a more serious concern than if the weight loss has
stabilized. Weight gain after a significant weight loss is a positive sign.
__________________________________
Medical history
Chronic illnesses
Surgical history
Psychosocial history
Socioeconomic history
History of GI problems (nausea, vomiting, diarrhea)
Diet history for weight gain or loss
Food preference and intolerance
Medications
Weight history ( increase or decrease, intentional or not, time period for change)
Functional capacity
________________________________________________________________
Physical Examination

A physical examination may reveal signs of nutritional deficiencies that require
further evaluation.

General evidence of muscle and fat wasting commonly noticed in the: 1) temporal
area, 2) shoulders, 3) hands, in the interosseous and palmar areas.

Less obvious physical parameters such as: 1) hair for color and sparseness; 2) skin for
turgor, pigmentation, and dermatitis; 3) mouth for glossitis, gingivitis, cheilosis, and
color of the tongue; 4) nails for friability and lines; and 5) the abdomen for ascites or
enlarged liver.
Anthropometrics

Physical examination may include anthropometrics that measure subcutaneous fat and
4
Professor T. Najjar
PHCL-474 (TPN)
Dept of clinical pharmacy
skeletal muscle mass.

Assessment of fat stores provides information about fat loss or gain and assumes fat
is gained or lost proportionally over the entire body.

Approximately 50% of body fat is in the subcutaneous compartment.

Measurement of skin folds thickness at various areas such as triceps and subscapular
are examples of methods to assess subcutaneous fat and therefore estimate total body
fat. The values obtained are compared with reference standards.

Measuring midarm circumference is used to estimate somatic protein mass or skeletal
muscle mass. These values also are compared with standards, and the amount of
muscle mass is estimated.

When used for the long-term study of large, nutritionally stable populations,
anthropometric measurements accurately reflect total body fat and skeletal muscle
mass.

However, anthropometric measurements of hospitalized patients are of limited value,
because during acute illness and stress, changes in subcutaneous fat may not be
proportional and peripheral edema results in inflated values for skinfold thickness and
midarm circumference and have no clinical application.
Biochemical Assessment
 Biochemical assessment of nutritional status includes measuring concentrations of
serum proteins. The visceral proteins most commonly used to assess nutritional status
are albumin, prealbumin, transferrin, and retinol-binding protein.

These proteins are synthesized by the liver and reflect its synthetic capability.

Serum concentrations decrease when intake of substrates is inadequate for synthesis
of these proteins or during stress or injury when substrates are shunted away from the
synthesis of these proteins to synthesize other proteins, acute phase reactants.

Serum concentrations of proteins are altered by both: 1) acute stress states and 2)
chronic starvation.

Albumin is the classic visceral protein used to evaluate nutritional status. Serum
concentrations of <3 g/dL correlate with poor outcome and increased length of stay of
hospitalized patients.

Albumin serves as a carrier protein for fatty acids, hormones, minerals, and drugs and
is necessary for maintaining oncotic pressure, Albumin has a large body pool of 3 to
5 g/kg and 30 to 40% is localized to the intravascular space.

The normal hepatic rate of albumin synthesis is 150 to 250 mg/kg per day.

Because albumin has a half-life of 18 to 21 days, a decrease in serum albumin
5
Professor T. Najjar
PHCL-474 (TPN)
Dept of clinical pharmacy
concentrations generally is not observed until after several weeks of inadequate
nitrogen intake.

Serum albumin concentrations decrease rapidly in response to non-nutritional factors
such as stress, which causes albumin to shift from the intravascular to the
extravascular space; burns; nephrotic syndrome; protein-losing enteropathy;
overhydration; and decreased synthesis with liver disease.

Transferrin is responsible for the transport of iron. It has a half-life of 8 to 10 days
and therefore is more sensitive than albumin to acute changes in nutritional status.
Normal serum concentrations for transferrin are 250 to 300 mg/dL.

Prealbumin: the more sensitive to changes in energy and protein intake is prealbumin
(transthyretin), which has a small body pool (10 mg/kg) and a half-life of 2 to 3 days.
Prealbumin transports retinol and retinol-binding protein. Normal serum prealbumin
concentrations are 15 to 40 mg/dL.

Retinol-binding protein has the shortest half-life, 12 hours, and has normal serum
concentrations of 2.5 to 7.5 mg/dL.

However, because serum concentrations of retinal-binding protein change rapidly in
response to alterations in nutrient intake, monitoring it has limited use in clinical
practice.

The visceral proteins commonly used for nutritional assessment are summarized in
the following table.
............ -------------------------------------------------------------------------------------------------Visceral Proteins for Nutritiorial Assessment
Visceral Protein
Half-Ufe (Days)
Normal Serum
Concentration
______________________________________________________
Albumin
18-21
3.5-5.0g/elL
Transferrin
8-10
250-300 mg/elL
Transthyretin (prealbumin)
2-3
15-40 mg/elL
Retinol-binding protein
0.5
2.5-7.5 mg/dL
---------------------------------------------------------------------------------
In general:

The interpretation of serum protein concentrations in hospitalized patients may be
difficult because factors more important than hepatic synthesis rate alter serum
concentrations.

These factors may include renal, hepatic, or cardiac dysfunction; hydration status;
and metabolic stress.

The use of visceral proteins, as with any nutritional assessment parameter, must be
used in conjunction with other parameters requires comprehensive consideration of
the patient's current clinical status.
6
Professor T. Najjar

PHCL-474 (TPN)
Dept of clinical pharmacy
Nutritional assessment based on determinations of body composition using
anthropometrics and biochemical parameters has many limitations.

New techniques (e.g., bioelectrical impedance, isotope dilution, and neutron
activation) are increasingly being used to determine body composition.

Other parameters such as forearm muscle dynamometry, which relates changes in
body composition to body function, also are being investigated.

Another nutritional assessment method, subjective global assessment (SGA),
combines objective parameters and physiologic function. This method is based on a
history of weight change, dietary intake, GI symptoms, and functional capacity, as
well as physical examination to assess the loss of subcutaneous fat and muscle and
the edema.

Using the SGA system, patients are rated as well nourished, moderately
malnourished, or severely malnourished. This subjective assessment is easy to use
and useful in diagnosing malnutrition.
Classification of Malnutrition

Protein-calorie malnutrition is divided classically into three categories: marasmus,
kwashiorkor, and a mixed protein-calorie.

Marasmus, which means a "dying away state," is seen in individuals who have a
chronic deficiency primarily in the intake of energy (calories) over a prolonged
period (i.e., partial starvation).

Physical examination reveals severe cachexia through loss of both fat and muscle
mass; however, visceral protein (e.g. albumin, prealbumin) production is preserved.

Kwashiorkor malnutrition results from a diet adequate in calories but limited in
protein. Insulin is produced to metabolize the carbohydrates and the insulin also
prevents lipolysis and promotes the movement of amino acids into muscle. To meet
protein needs, protein is mobilized from internal organs and circulating visceral
proteins such as albumin.

Thus an individual with kwashiorkor malnutrition has adequate fat and muscle mass
but depleted serum proteins.

Hospitalized patients commonly exhibit components of both marasmus and
kwashiorkor malnutrition, and are classified as having mixed protein-calorie
malnutrition. This often occurs when an injury or stress compounds chronic
starvation or semistarvation. With already limited fat and muscle mass, and stress
creating increased energy needs, the end result is wasting of fat and muscle mass, as
well as depletion of serum proteins.
7
Professor T. Najjar
PHCL-474 (TPN)
8
Dept of clinical pharmacy