Spirometry and Related Tests RET 2414 Pulmonary Function Testing.

Spirometry and Related Tests

RET 2414Pulmonary Function Testing

SPIROMETRY AND RELATED TESTS

Learning Objectives

Determine whether spirometry is acceptable and reproducible

Identify airway obstruction using forced vital capacity (FVC) and forced expiratory volume (FEV1)

Differentiate between obstruction and restriction as causes of reduced vital capacity

SPIROMETRY AND RELATED TESTS

Learning Objectives

Distinguish between large and small airway obstruction by evaluating flow-volume curves

Determine whether there is a significant response to bronchodilators

Select the appropriate FVC and FEV1 for reporting from series of spirometry maneuvers

Spirometry: Airway Function Tests

The word spirometry means “the measuring of breath.” It is the most common of the Pulmonary Function Tests (PFTs).

It measures lung function, specifically the direct measurement of the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled.

VC: Volume

FVC: Volume & Flow


Vital Capacity (VC)

Forced Vital Capacity

Flow Volume Loop

Pre/Post Bronchodilator Pre/Post Bronchochallenge


Maximum Voluntary Ventilation (MVV)

Maximal Inspiratory (MIP)

Expiratory Pressure (MEP)

Airway Resistance (Raw)

Compliance (CL)

Indications for Spirometry

Detect the presence of lung disease

Spirometry is recommended as the “Gold Standard” for diagnosis of obstructive lung disease by:

National Lung Health Education Program (NLHEP)

National Heart, Lung and Blood Institute (NHLBI)

World Health Organization (WHO)

Indications for Spirometry BOX 1-2

Diagnose the presence or absence of lung disease

Quantify the extent of known disease on lung function

Measure the effects of occupational or environmental exposure

Indications for Spirometry BOX 1-2

Determine beneficial or negative effects of therapy

Assess risk for surgical procedures

Evaluate disability or impairment

Epidemiologic or clinical research involving lung health or disease

SPIROMETRY

Vital Capacity

The vital capacity (VC) is the volume of gas measured from a slow, complete expiration after a maximal inspiration, without a forced effort.

SPIROMETRY

Vital Capacity

SPIROMETRY

Vital Capacity

Valid VC measurements important IC and ERV used to calculate

RV and TLC

Example: RV = FRC - ERV TLC = IC + FRC

SPIROMETRY

VC: Criteria for Acceptability1. End-expiratory volume varies by less than 100 ml for

three preceding breaths

2. Volume plateau observed at maximal inspiration and expiration

SPIROMETRY

VC: Criteria for Acceptability3. Three acceptable VC maneuvers should be obtained;

volume within 150 ml.

4. VC should be within 150 ml of FVC value

SPIROMETRY

VC: Selection Criteria

The largest single value from at least 3 acceptable maneuvers should be reported

SPIROMETRY

VC: Significance/Pathophysiology

Decreased VC Loss of distensible lung tissue

Lung CA Pulmonary edema Pneumonia Pulmonary vascular congestion Surgical removal of lung tissue Tissue loss Space-occupying lesions Changes in lung tissue

SPIROMETRY


Decreased VC Obstructive lung disease Respiratory depression or

neuromuscular disease Pleural effusion Pneumothorax Hiatal hernia Enlarged heart

SPIROMETRY


Decreased VC Limited movement of diaphragm

Pregnancy Abdominal fluids Tumors

Limitation of chest wall movement Scleraderma Kyphoscoliosis Pain

Predicted Values

Laboratory Normal Ranges

Laboratory tests performed on a large number of normal population will show a range of results

Predicted Values


Predicted Values


Most clinical laboratories consider two standard deviations from the mean as the normal range since it includes 95% of the normal population.

PFT Reports

o When performing PFT’s three values are reported:

o Actual – what the patient performed

o Predicted – what the patient should have performed based on Age, Height, Sex, Weight, and Ethnicity

o % Predicted – a comparison of the actual value to the predicted value

PFT Reports

Example

Actual Predicted %Predicted

VC 4.0 5.0 80%

SPIROMETRY


If the VC is less than 80% of predicted: FVC can reveal if caused by obstruction

SPIROMETRY


If the VC is less than 80% of predicted: Lung volume testing can reveal if caused by restriction

SPIROMETRY

Forced Vital Capacity (FVC)

The maximum volume of gas that can be expired when the patient exhales as forcefully and rapidly as possible after maximal inspiration (sitting or standing)

SPIROMETRY

FVC (should be within 150 ml of VC)

SPIROMETRY

FVC: Criteria for Acceptability1. Maximal effort; no cough or glottic closure

during the first second; no leaks or obstruction of the mouthpiece.

2. Good start-of-test; back extrapolated volume <5% of FVC or 150 ml, whichever is greater

SPIROMETRY

FVC: Criteria for Acceptability

3. Tracing shows 6 seconds of exhalation or an obvious plateau (<0.025L for ≥1s); no early termination or cutoff; or subject cannot or should not continue to exhale

SPIROMETRY

FVC: Criteria for Acceptability

4. Three acceptable spirograms obtained; two largest FVC values within 150 ml; two largest FEV1 values within 150 ml

SPIROMETRY

FVC: Selection Criteria

The largest FVC and largest FEV1 (BTPS) should be reported, even if they do not come from the same curve

SPIROMETRY

FVC: When to call it quits !!!

If reproducible values cannot be obtained after eight attempts, testing may be discontinued

SPIROMETRY

FVC: Significance and Pathophysiology

FVC equals VC in healthy individuals

FVC is often lower in patients with obstructive disease

SPIROMETRY


FVC can be reduced by:

Mucus plugging Bronchiolar narrowing Chronic or acute asthma Bronchiectasis Cystic fibrosis Trachea or mainstem bronchi obstruction

SPIROMETRY


Healthy adults can exhale their FVC within 4 – 6 seconds

Patients with severe obstruction (e.g., emphysema) may require 20 seconds, however, exhalation times >15 seconds will rarely change clinical decisions

SPIROMETRY


FVC is also decreased in restrictive lung disease

Pulmonary fibrosis dusts/toxins/drugs/radiation

Congestion of pulmonary blood flow pneumonia/pulmonary hypertension/PE

Space occupying lesions tumors/pleural effusion

SPIROMETRY


FVC is also decreased in restrictive lung disease

Neuromuscular disorders, e.g, myasthenia gravis, Guillain-Barre

Chest deformities, e.g, scoliosis/kyphoscoliosis

Obesity or pregnancy

SPIROMETRY

Forced Expiratory Volume (FEV1)

The volume expired over the first second of an FVC maneuver

SPIROMETRY


FEV1 is the most widely used spirometric parameter, particularly for assessment of airway obstruction

SPIROMETRY


FEV1 is used in conjunction with FVC for:

Simple screening Response to bronchodilator therapy Response to bronchoprovocation Detection of exercise-induced

bronchospasm

SPIROMETRY

Forced Expiratory Volume (FEV1) May be reduced in obstructive or

restrictive patterns, or poor patient effort

SPIROMETRY


In obstructive disease, FEV1 may be decreased because of:

Airway narrowing during forced expiration emphysema

Mucus secretions Bronchospasm Inflammation (asthma/bronchitis) Large airway obstruction

tumors/foreign bodies

SPIROMETRY


The ability to work or function in daily life is related to the FEV1 and FVC

Patients with markedly reduced FEV1 values are more likely to die from COPD or lung cancer

SPIROMETRY


FEV1 may be reduced in restrictive lung processes

Fibrosis Space-occupying lesions Neuromuscular diseases Obesity Chest wall deformity

SPIROMETRY

Forced Expiratory Volume Ratio (FEVT%)

FEVT% = FEVT/FVC x 100

Useful in distinguishing between obstructive and restrictive causes of reduced FEV1 values

SPIROMETRY


Normal FEVT% Ratios for Health Adults

FEV 0.5% = 50%-60%

FEV 1% = 75%-85%

FEV 2% = 90%-95%

FEV 3% = 95%-98%

FEV 6% = 98%-100%

Patients with obstructive disease have reduced FEVT% for each interval

SPIROMETRY


A decrease FEV1/FVC ratio is the “hallmark” of obstructive disease

FEV1/FVC <75%

SPIROMETRY


Patients with restrictive disease often have normal or increased FEVT% values

FEV1 and FVC are usually reduced in equal proportions

The presence of a restrictive disorder may by suggested by a reduced FVC and a normal or increased FEV1/FVC ration

SPIROMETRY

Forced Expiratory Flow 25% - 75%(maximum mid-expiratory flow)

FEF 25%-75% is measured from a segment of the FVC that includes flow from medium and small airways

Normal values: 4 – 5 L/sec

SPIROMETRY

Forced Expiratory Flow 25% - 75%

In the presence of a borderline value for FEV1/FVC, a low FEF 25%-75% may help confirm airway obstruction

SPIROMETRY

Flow – Volume Curve AKA: Flow–Volume Loop (FVL)

The maximum expiratory flow-volume (MEFV) curve shows flow as the patient exhales from maximal inspiration (TLC) to maximal expiration (RV)

FVC followed by FIVC

SPIROMETRY

FVL X axis: Volume

Y axis: Flow

PEF (Peak Expiratory Flow)

PIF (Peak Inspiratory Flow) .

Vmax 75 or FEF 25% FVC Remaining or Percentage FVC exhaled

.

Vmax 50 or FEF 50% .

Vmax 25 or FEF 75%

FEF 25% or Vmax 75

FEF 75% or Vmax 25%

SPIROMETRY

FVL

FEVT and FEF% can be read from the timing marks (ticks) on the FVL

SPIROMETRY

FVL Significant decreases in flow or volume

are easily detected from a single graphic display

SPIROMETRY

FVL: Severe Obstruction

SPIROMETRY

FVL: Bronchodilation

SPIROMETRY

Peak Expiratory Flow (PEF)

The maximum flow obtained during a FVC maneuver

Measured from a FVL In laboratory, must perform a

minimum of 3 PEF maneuvers Largest 2 of 3 must be within 0.67 L/S

(40 L/min) Primarily measures large airway

function Many portable devices available

SPIROMETRY

Peak Expiratory Flow (PEF)

When used to monitor asthmatics

Establish best PEF over a 2-3 week period

Should be measured twice daily (morning and evening)

Daily measurements are compared to personal best

SPIROMETRY

Peak Expiratory Flow (PEF) The National Asthma Education Program

suggests a zone system Green: 80%-100% of personal best

Routine treatment can be continued; consider reducing medications

Yellow: 50%-80% of personal best Acute exacerbation may be present Temporary increase in medication may be

needed Maintenance therapy may need increases

Red: Less than 50% of personal best Bronchodilators should be taken immediately;

begin oral steroids; clinician should be notified if PEF fails to return to yellow or green within 2 – 4 hours

SPIROMETRY

Peak Expiratory Flow (PEF) PEF is a recognized means of

monitoring asthma

Provides serial measurementsof PEF as a guide to treatment

ATS Recommended Ranges 60-400 L/min (children) 100-850 L/min (adults)

SPIROMETRY

Maximum Voluntary Ventilation (MVV)

The volume of air exhaled in a specific interval during rapid, forced breathing

SPIROMETRY

MVV Rapid, deep breathing VT ~50% of VC For 12-15 seconds

SPIROMETRY

MVV

Tests overall function of respiratory system

Airway resistance

Respiratory muscles

Compliance of lungs/chest wall

Ventilatory control mechanisms

SPIROMETRY

MVV At least 2 acceptable maneuvers should be

performed

Two largest should be within 10% of each other

Volumes extrapolated out to 60 seconds and corrected to BTPS

MVV is approximately equal to 35 time the FEV1

SPIROMETRY

MVV Selection Criteria

The highest MVV (L/min, BTPS) and MVV rate (breaths / min) should be reported

SPIROMETRY

MVV

Decreased in:

Patients with moderate to severe obstructive lung disease

Patients who are weak or have decreased endurance

Patients with neurological deficits

SPIROMETRY

MVV

Decreased in:

Patients with paralysis or nerve damage

A markedly reduced MVV correlates with postoperative risk for patients having abdominal or thoracic surgery

SPIROMETRY

Before/After Bronchodilator

Spirometry is performed before and after bronchodilator administration to determine the reversibility of airway obstruction

SPIROMETRY


An FEV1% less than predicted is a good indication for bronchodilator study

In most patients, an FEV1% less than 70% indicates obstruction

SPIROMETRY


Any pulmonary function parameter may be measured before and after bronchodilator therapy

FEV1 and specific airway conductance (SGaw) are usually evaluated

SPIROMETRY


Lung volumes should be recorded before bronchodilator administration

Lung volumes and DLco may also respond to bronchodilator therapy

SPIROMETRY


Routine bronchodilator therapy should be withheld prior to spirometry

Ruppel 9th edition, pg. 66: Table 2-2

Short-acting β-agonists 4 hours Short-acting anticholinergic 4 hours Long-acting β-agonists 12 hours Long-acting anticholinergic 24 hours Methylxanthines (theophyllines) 12 hours Slow release methylxanthines 24 hours Cromolyn sodium 8-12 hours Leukotriene modifiers 24 hours Inhaled steroids Maintain dosage

SPIROMETRY


Minimum of 10 minutes, up to 15 minutes, between administration and repeat testing is recommended (30 minutes for short-acting anticholinergic agents)

FEV1, FVC, FEF25%-75%, PEF, SGaw are commonly made before and after bronchodilator administration

SPIROMETRY


Percentage of change is calculated

%Change = Postdrug – Predrug X 100Predrug

SPIROMETRY


FEV1 is the most commonly used test for quantifying bronchodilator response

FEV1% should not be used to judge bronchodilation response

SGaw may show a marked increase after bronchodilator therapy

SPIROMETRY


Significance and Pathophysiology

Considered significant if:

FEV1 or FVC increase ≥12% and ≥200 ml

SGaw increases 30% - 40%

SPIROMETRY



Diseases involving the bronchial (and bronchiolar) smooth muscle usually improve most from “before” to “after”

Increase >50% in FEV1 may occur in patients with asthma

SPIROMETRY



Patients with chronic obstructive diseases may show little improvement in flows

Inadequate drug deposition (poor inspiratory effort)

Patient may respond to different drug Paradoxical response <8% or 150 ml not

significant

SPIROMETRY & Related Tests

Maximal Inspiratory Pressure (MIP)

The lowest pressure developed during a forceful inspiration against an occluded airway

Primarily measures inspiratory muscle strength


MIP

Usually measured at maximal expiration (residual volume)

Can be measured at FRC

Recorded as a negative number in cm H20 or mm Hg, e.g. (-60 cm H2O)


MIP


MIP


Healthy adults > -60 cm H2O Decreased in patients with:

Neuromuscular disease

Diseases involving the diaphragm, intercostal, or accessory muscles

Hyperinflation (emphysema)


MIP


Sometimes used to measure response to respiratory muscle training

Often used in the assessment of respiratory muscle function in patients who need ventilatory support


Maximal Expiratory Pressure (MEP)

The highest pressure developed during a forceful exhalation against an occluded airway

Dependent upon function of the abdominal muscles, accessory muscles of expiration, and elastic recoil of lung and thorax


MEP

Usually measured at maximal inspiration (total lung capacity)

Can be measured at FRC

Recorded as a positive number in cm H20 or mm Hg


MIP and MEP


MEP


Healthy adults >80 to 100 cm H2O Decreased in:

Neuromuscular disorders

High cervical spine fractures

Damage to nerves controlling abdominal and accessory muscles of expiration


MEP


A low MEP is associated with inability to cough

May complicate chronic bronchitis, cystic fibrosis, and other diseases that result in excessive mucus production



The drive pressure required to create a flow of air through a subject’s airway

Recorded in cm H2O/L/sec

When related to lung volume at the time of measurement it is known as specific airway resistance (SRaw)


Raw

Measured in a plethysmograph as the patient breathes through a pneumo-tachometer


Raw Criteria of Acceptability

Mean of three or more acceptable efforts should be reported; individual values should be within 10% of mean



Normal Adult Values

Raw 0.6 – 2.4 cm H2O/L/sec

SRaw 0.190 – 0.667 cm H2O/L/sec/L



May be increased in:

Bronchospasm Inflammation Mucus secretion Airway collapse Lesions obstructing the larger airways

Tumors, traumatic injuries, foreign bodies


RawSignificance and Pathology

Increased in acute asthmatic episodes

Increased in advanced emphysema because of airway narrowing and collapse

Other obstructive disease, e.g., bronchitis may cause increase in Raw proportionate to the degree of obstruction in medium and small airways


Airway Conductance (Gaw)

A measure of flow that is generated from the available drive pressure

Recorded in L/sec/cm H2O

Gaw is the inverse of Raw

When related to lung volume at the time of measurement it is known as specific airway conductance (SGaw)


Gaw

Measured in a plethysmograph as the patient breathes through a pneumo-tachometer


Gaw Criteria of Acceptability

Mean of three or more acceptable efforts should be reported; individual values should be within 10% of mean



Normal Adult Values

Gaw 0.42 – 1.67 L/sec/cmH2O

SGaw 0.15 – 0.20 L/sec/cm H2O/L



Significance and Pathology

SGaw Values <0.15 – 0.20 L/sec/cm H2O/L are consistent with airway obstruction

Quiz Practice

Most clinical laboratories consider two standard deviations from the mean as the normal range when determining predicted values since it includes 95% of the normal population.a. Falseb. Only for those individuals with lung

diseasec. This applies only to cigarette smokersd. True

Quiz Practice

Vital capacity is defined as which of the following?a. The volume of gas measured from a slow,

complete exhalation after a maximal inspiration, without a forced effort

b. The volume of gas measured from a rapid, complete exhalation after a rapid maximal inspiration

c. The volume of gas measured after 3 seconds of a slow, complete exhalation

d. The total volume of gas within the lungs after a maximal inhalation

Quiz Practice

Which of the following statements are true regarding the acceptability criteria for vital capacity measurement?

I. End-expiratory volume varies by less than 100 ml for three preceding breaths

II. Volume plateau observed at maximal inspiration and expiration

III. Three acceptable vital capacity maneuvers should be obtained; volume within 150 ml

IV. Vital capacity should be within 150 ml of forced vital capacity in healthy individuals

a. I, II, and IVb. II, III, and IVc. III and IVd. I, II, III, IV

Quiz Practice

Which of the following best describes the Forced Vital Capacity (FVC) maneuver?

a. The volume of gas measured from a slow, complete exhalation after a maximal inspiration, without a forced effort

b. The volume of gas measured from a slow, complete exhalation after a rapid maximal inspiration

c. The volume of gas measured after 3 seconds of a rapid, complete exhalation

d. The maximum volume of gas that can be expired when the patient exhales as forcefully and rapidly as possible after maximal inspiration

Quiz Practice

All of the following are true regarding the acceptability criteria of an FVC maneuver EXCEPT?

a. Maximal effort, no cough or glottic closure during the first second; no leaks of obstruction of the mouthpiece

b. Good start of test; back extrapolated volume less than 5% of the FVC or 150 ml

c. Tracing shows a minimum of 3 seconds of exhalation

d. Three acceptable spirograms obtained; two largest FVC values within 150 ml; two largest FEV1 values within 150 ml

Quiz Practice

The FEV1 is the expired volume of the first second of the FVC maneuver.

a. Trueb. Falsec. Only when done slowlyd. Only when divided by the FVC

Quiz Practice

Which of following statements is true regarding FEV1?

a. FEV1 may be larger than the FVCb. FEV1 is always 75% of FVCc. May be reduced in obstructive and

restrictive lung diseased. Is only reduced in restrictive disease

Quiz Practice

The FEV1% is useful in distinguishing between obstructive and restrictive causes of reduced FEV1 values

a. Trueb. Falsec. Only helps to distinguish obstructive

lung diseased. Only helps to distinguish restrictive

lung disease

Quiz Practice

Which statements are true regarding the FEV 1%, also known as the FEV1/FVC?

I. A decreased FEV1/FVC is the hallmark of obstructive disease

II. Patients with restrictive lung disease often have normal or increased FEV1/FVC ratios

III. The presence of a restrictive disorder may be suggested by a reduced FVC and a normal or increased FEV1/FVC ratio

IV. A normal FEV1/FVC ratio is between 75% - 85%

a. I and IIb. I, II and IIIc. II, III and IVd. I, II, III and IV

Quiz Practice

What test is represented by the graph to the right?

a. Forced Vital Capacity

b. Flow-Volume Loopc. Slow Vital Capacityd. Total Lung Capacity

Maneuver

Quiz Practice

What type of pulmonary disorder is represented by the graph below?

a. Obstructive lung diseaseb. Restrictive lung diseasec. Upper airway obstructiond. Normal lung function

(The dotted lines represent the predicted values)

Quiz Practice

Which is true regarding Peak Expiratory Flow (PEF)?

I. Primarily measures large airway functionII. Is a recognized means of monitoring

asthmaIII. Serial measurements of PEF are used a

guide to treat asthmaIV. When less than 50% of personal best, it is

an indication that immediate treatment is required

a. I onlyb. II and IIIc. II, III, and IVd. I, II, III, and IV

Quiz Practice

MVV is decreased in patients with which of the following disorders?

I. Moderate to severe obstructive lung disease

II. Weak or with decrease enduranceIII. Neurological defectsIV. Paralysis or nerve damage

a. I and IVb. II and IIIc. III and IVd. I, II, III, and IV

Quiz Practice

Spirometry before and after bronchodilator therapy is used to determine which of the following?

a. Reversibility of airway obstructionb. The severity of restrictive disordersc. The rate at which CO diffuses through the lung

into the bloodd. If the patient has exercised induced asthma

Quiz Practice

What is the minimum amount of time between administration of bronchodilator therapy and repeat pulmonary function testing?

a. 5 minutesb. 10 minutesc. 30 minutesd. 60 minute

Quiz Practice

Bronchodilation is considered significant when which of the following occurs?

a. FEV1/FVC increases by 12%b. SGaw increases by 12%c. FVC and/or FEV1 increases by 12% and 200 mld. DLco increases by 12%

Quiz Practice

Which of the following is true regarding Maximal Inspiratory Pressure (MIP)?

I. Primarily measures inspiratory muscle strength

II. Measures airway resistance during inspiration

III. Is decreased in patients with neurological disease

IV. Often used in the assessment of respiratory muscle function in patients who need ventilatory support

a. I, II, and IIIb. I, III, and IVc. II and IIId. II, III, and IV

Quiz Practice

Airway resistance (Raw) is the drive pressure required to create a flow of air through a subject’s airway.

a. Trueb. Falsec. Only in patients with COPDd. Only in patients with restrictive

disorders

Quiz Practice

Airway resistance may be increased in which of the following patients?

I. Purely restrictive lung disordersII. Acute asthmatic episodesIII. Mucus secretionIV. Lung compliance changes

a. I onlyb. I and IVc. II and IIId. I, II, III, and IV

Quiz Practice

Airway Conductance (Gaw) is a measure of flow that is generated from the available drive pressure.

a. Trueb. Falsec. Only in patients with COPDd. Only in patients with restrictive

disorders

Quiz Practice

A patient’s pulmonary function tests reveal the following:

Actual Predicted %Predicted

FVC 4.01 L 4.97 L 81 FEV1 2.58 L 3.67 L 56 FEV1% 51 >75 _

Select the correct interpretationa. Restrictive patternb. Obstructive patternc. Inconclusived. Normal

Quiz Practice

A patient’s pulmonary function tests reveal the following:

Actual Predicted %PredictedFVC 3.75 L 4.97 L 75FEV1 2.80 L 3.67 L 76FEV1% 75 >/=75 _

Select the correct interpretationa. Restrictive patternb. Obstructive patternc. Inconclusived. Normal

Spirometry and Related Tests RET 2414 Pulmonary Function Testing.

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