Download WLK_Chapter_018_NutritionalAssess

Chapter 18
Nutritional Assessment of
Patients with Respiratory
Disease
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Learning Objectives
After reading this chapter you will be able to:
 Recognize how nutrition and respiration
are interrelated
 Recognize the functional importance of
oxygen in nutrition
 Identify the nutritional significance of
measuring oxygen uptake
 Identify the value of determining the basal
metabolic rate and basal energy
expenditure
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Learning Objectives (cont’d)

Recognize how starvation affects:
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Body weight
Muscle mass (diaphragm and other respiratory
musculature)
Forced vital capacity, forced expiratory volume
in 1 second, and diffusing capacity of the lung
for carbon dioxide
Surfactant production
Know how some respiratory treatment
modalities inhibit patient nutritional status
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Learning Objectives (cont’d)
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Identify the by-products of anaerobic
(without oxygen) metabolism
Identify oxygen’s importance in terms of
adenosine triphosphate production
Identify how fat, carbohydrate, and protein
metabolism affect the respiratory quotient
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Learning Objectives (cont’d)
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Recognize the daily nutritional
requirements for carbohydrate, protein,
and fat
Identify the protein requirements for
normal and severely catabolic patients
Recognize the significance of measuring
nitrogen balance
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Learning Objectives (cont’d)
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Recognize the problems associated with a
low-protein diet
Recognize the advantages and
disadvantages of a high-carbohydrate diet
in regard to the pulmonary system
Identify the importance of vitamins and
minerals in respiratory function
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Learning Objectives (cont’d)
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State the methods available for meeting
nutritional requirements and their
advantages and disadvantages
Recognize the methods for assessing
nutritional status
Identify the role of the RT in nutritional
assessment in relation to inspection,
auscultation, and laboratory findings
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Introduction
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Nutritional status has major influence on
patient outcomes
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Provides energy for breathing and movement
Food quality and quantity affect oxygen
needs and CO2 production
Nutrients influence lung immune function
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Interdependence of
Respiration and Nutrition
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O2 and nutrients travel in the blood to
tissues
Nutrient conversion to energy at cellular
level requires O2 to support the process
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Aerobic metabolism required for life
Breathing fuels the metabolic process
Thus breathing is part of nutrition
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Interdependence of
Respiration and Nutrition (cont’d)
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Metabolic rate determines oxygen uptake
(VO2)
By measuring VO2 at rest, the basal
metabolic rate (BMR) or resting energy
expenditure (REE) can be calculated
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Interdependence of Respiration
and Nutrition (cont’d)
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Harris-Benedict equation: basal energy
expenditure (BEE) of healthy person at
rest
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Men: 66 + (13.7 × W) + (5 × H) – (6.8 × age)
Women: 655 + (9.6 × W) + (1.7 × H) – (4.7 ×
age) (W = weight in Kg, H = height in cm)
True energy measurements are better
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Direct calorimetry
Indirect calorimetry
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Interdependence of Respiration
and Nutrition (cont’d)
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Direct calorimetry
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Special room measures heat produced by
metabolism
Metabolism generates heat, measured in
calories
This is not practical clinically
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Interdependence of Respiration
and Nutrition (cont’d)
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Indirect calorimetry
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VO2 and VCO2 to determine energy
consumption VO2 correlates directly with ATP
production
• The higher the metabolic rate, the higher the VO2
This is now measured with a metabolic cart
• Now portable
• Easiest to perform on ventilated patients
• Nose clips and mouthpiece required for
spontaneously breathing patients
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Nutritional Depletion and
Respiration
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12 to 16 hours of insufficient carbohydrate
intake will result in gluconeogenesis
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Process of converting muscle and enzyme
proteins into sugar
This leads to functional tissue loss
In starvation:
• Muscles lose endurance and strength (including
those of respiration)
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Noted by decreased FVC, FEV1, and DLCO
Diminished immune function because antibodies are
proteins
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Nutritional Depletion and
Respiration (cont’d)
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Emphysema produces a catabolic state
typically with weight loss even with normal
caloric intake
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REE high in malnourished emphysemic patient
Exacerbates symptoms of COPD
• Diminished respiratory muscle strength and exercise
tolerance
• Compromised immune function, thus increased
pulmonary infections
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Increased intake of food can normalize weight
• Emphysemic patients are not comfortable eating
large quantities of food
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Therapeutic Interactions of
Respiration and Nutrition
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Respiratory therapy may hinder nutrition
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Bronchodilators cause nausea
Nasal oxygen interferes with smell and taste
Medications can interact to render nutrients
less useful or inhibit some metabolic enzymes
Intubation complicates eating process
Large meals interfere with diaphragm
movement
Anxiety, depression often reduce appetite
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Therapeutic Interactions of
Respiration and Nutrition (cont’d)
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Semistarved states can decrease hypoxic
drive
Critically ill patients require constant aid
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Breathing: intubation, mechanical ventilation
Feeding: NG tube or even total parenteral
nutrition (TPN)
Matching energy and nutritional needs with
ventilatory needs can be challenging
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Respiratory System and
Nutritional Needs
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Metabolism
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Body energy is produced by metabolism
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Transfers food to ATP—body’s energy source
• Can occur by aerobic or anaerobic metabolism
• Oxygen is consumed in the aerobic pathway
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Very efficient yield of ATP
Waste product is CO2, which is exhaled
• Anaerobic pathway occurs without oxygen
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Very inefficient
Waste product is lactic acid; may result in lactic
acidosis
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Metabolism (cont’d)
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Amount of CO2 produced by aerobic
metabolism is determined by the fuel
burned
Described by the RQ: CO2 production
divided by oxygen consumption
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Fat has RQ of 0.7
Protein has RQ of 0.85
Carbohydrate has RQ of 1
 Burning a combination of the above produces
a normal RQ (VCO2/VO2) of 0.8
• That is 200 ml CO2/250 ml O2
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Nutritional Requirements
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Basic: carbohydrate, protein, fat, vitamins,
minerals, water, and O2
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Carbs, proteins, fats provide energy and
building blocks
Vitamins facilitate metabolic pathway reactions
Minerals provide elements for molecules
Water provides fluidity for blood flow and
medium for various chemical reactions
Oxygen: without it everything stops
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Nutritional Requirements (cont’d)
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Carbohydrate (sugar)
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Should be largest amount of dietary intake
Complex carbs in grains, vegetables, fruits
Simple sugars present in the above foods but
primarily found in refined processed foods
Patients with severe COPD may do better with
a lower-carbohydrate, higher-fat diet due to
reduced CO2 production
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Nutritional Requirements (cont’d)
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Protein
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Should comprise 12% to 15% of intake
Recommended daily amount (RDA) varies
• 0.8 g/kg for healthy individual
• 1.2 to 1.5 g/kg for average hospital patient
• 2 to 2.5 g/kg for severe catabolic patients
Nitrogen found only in protein amino acids
• Quick estimate of protein catabolism is made by
multiplying blood urea nitrogen (BUN) by 6.25
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Nutritional Requirements (cont’d)
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Fat
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Carries fat soluble vitamins: A, D, E, K
• Important for immunity, clotting, antioxidants, etc.
Fats twice as calorie dense as other nutrients
• Thus efficient for increasing caloric intake for patients
on fluid restrictions
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Higher fat content may decrease dyspnea for
COPD patients
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Nutritional Requirements (cont’d)
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Vitamins
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Fat soluble (A, D, E, K)
Water soluble (B group and C)
Co-factors in enzyme systems for various
metabolic functions
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Nutritional Requirements (cont’d)
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Minerals
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Used in chemical reactions and enzyme
systems
Iron key for role in O2 transport on hemoglobin
Omega-3 useful anti-inflammatory for
asthmatics
Fluid balance important for mucociliary
clearance
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Methods of Meeting
Nutritional Requirements
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Nutritional administration route: enteral or
parenteral
Enteral is preferred as most natural
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By mouth if possible (emphysema patient more
frequent small meals)
If intubated maybe by NG tube, PEG tube
Parenteral (last resort)
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If GI tract not functioning, patient may require
TPN, which is IV infusion of all nutrients
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Nutritional Assessment
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Role of RTs in
Nutritional Assessment
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Inspection findings
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Cachectic patients are bony with depressed
intercostal spaces
Accessory muscles are often readily visible
Poor cough secondary to muscle weakness
Viscous secretions may suggest dehydration
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Role of RTs in Nutritional
Assessment (cont’d)
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Auscultation findings
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Basilar coarse or fine crackles may indicate
fluid overload or loss of blood protein
Wheezing secondary to food
intolerance/allergy
Fine late inspiratory crackles may indicate
diminished surfactant secondary to malnutrition
S3 may indicate fluid overload and CHF
S4 may indicate severe anemia
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Role of RTs in Nutritional
Assessment (cont’d)
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Laboratory findings
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PFT changes: decreased FVC, FEV1, PEP,
PIP
ABG changes:
• Hypercarbia with acidosis due to excessive nutrition
or ventilatory failure
• Anemias decrease oxygen carrying capacity of
hemoglobin and thus CaO2
• High-fat intake may cause a low PaO2
• pH alterations
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Secondary to foods that are alkalotic or acidotic
Lactic acidosis due to low PaO2
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Summary
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O2 is crucial for the production of ATP
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ATP fuels all body functions
BMR can be determined if VO2 is known
RT can interfere with nutrition
Patients with severe COPD may do better
with higher-fat, lower-carbohydrate diets
Intubated patients typically fed by NG tube
TPN is used only as a last resort
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