Chapter 18 Nutritional Assessment of Patients with Respiratory Disease

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Chapter 18 Nutritional Assessment of Patients with Respiratory

Disease


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


Learning Objectives (cont’d)

Recognize how starvation affects: 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



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


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




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


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



Introduction

Nutritional status has major influence on patient outcomes Provides energy for breathing and movement

Food quality and quantity affect oxygen needs and CO2 production

Nutrients influence lung immune function


Interdependence of Respiration and Nutrition

O2 and nutrients travel in the blood to tissues

Nutrient conversion to energy at cellular level requires O2 to support the process Aerobic metabolism required for life Breathing fuels the metabolic process Thus breathing is part of nutrition


Interdependence of Respiration and Nutrition (cont’d)

Metabolic rate determines oxygen uptake (VO2)

By measuring VO2 at rest, the basal metabolic rate (BMR) or resting energy expenditure (REE) can be calculated



Harris-Benedict equation: basal energy expenditure (BEE) of healthy person at rest 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 Direct calorimetry Indirect calorimetry



Direct calorimetry Special room measures heat produced by

metabolism Metabolism generates heat, measured in

calories This is not practical clinically



Indirect calorimetry 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


Nutritional Depletion and Respiration

12 to 16 hours of insufficient carbohydrate intake will result in gluconeogenesis 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)

Noted by decreased FVC, FEV1, and DLCO Diminished immune function because antibodies are

proteins


Nutritional Depletion and Respiration (cont’d)

Emphysema produces a catabolic state typically with weight loss even with normal caloric intake REE high in malnourished emphysemic patient Exacerbates symptoms of COPD

• Diminished respiratory muscle strength and exercise tolerance

• Compromised immune function, thus increased pulmonary infections

Increased intake of food can normalize weight• Emphysemic patients are not comfortable eating

large quantities of food


Therapeutic Interactions of Respiration and Nutrition

Respiratory therapy may hinder nutrition 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


Therapeutic Interactions of Respiration and Nutrition (cont’d)

Semistarved states can decrease hypoxic drive

Critically ill patients require constant aid Breathing: intubation, mechanical ventilation Feeding: NG tube or even total parenteral

nutrition (TPN) Matching energy and nutritional needs with

ventilatory needs can be challenging


Respiratory System and Nutritional Needs


Metabolism

Body energy is produced by metabolism Transfers food to ATP—body’s energy source

• Can occur by aerobic or anaerobic metabolism• Oxygen is consumed in the aerobic pathway

Very efficient yield of ATP Waste product is CO2, which is exhaled

• Anaerobic pathway occurs without oxygen Very inefficient Waste product is lactic acid; may result in lactic

acidosis


Metabolism (cont’d)

Amount of CO2 produced by aerobic metabolism is determined by the fuel burned

Described by the RQ: CO2 production divided by oxygen consumption 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


Nutritional Requirements

Basic: carbohydrate, protein, fat, vitamins, minerals, water, and O2 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


Nutritional Requirements (cont’d)

Carbohydrate (sugar) 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


Protein 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



Fat 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

Higher fat content may decrease dyspnea for COPD patients



Vitamins Fat soluble (A, D, E, K) Water soluble (B group and C) Co-factors in enzyme systems for various

metabolic functions



Minerals 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



Methods of Meeting Nutritional Requirements

Nutritional administration route: enteral or parenteral

Enteral is preferred as most natural By mouth if possible (emphysema patient more

frequent small meals) If intubated maybe by NG tube, PEG tube

Parenteral (last resort) If GI tract not functioning, patient may require

TPN, which is IV infusion of all nutrients


Nutritional Assessment


Role of RTs in Nutritional Assessment

Inspection findings 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


Role of RTs in Nutritional Assessment (cont’d)

Auscultation findings 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


Role of RTs in Nutritional Assessment (cont’d)

Laboratory findings 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

Secondary to foods that are alkalotic or acidotic Lactic acidosis due to low PaO2


Summary

O2 is crucial for the production of ATP 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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Chapter 18 Nutritional Assessment of Patients with Respiratory Disease