spirometry and related tests

Spirometry and Related Tests

RET 2414Pulmonary Function TestingModule 2.0

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

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

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 CriteriaThe largest 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


Obstructive lung disease Respiratory depression or

neuromuscular disease Pleural effusion Pneumothorax Hiatal hernia Enlarged heart

SPIROMETRY


Limited movement of diaphragm Pregnancy Abdominal fluids Tumors

Limitation of chest wall movement Scleraderma Kyphoscoliosis Pain

SPIROMETRY

VC: Significance/Pathophysiology If the VC is less than 80% of

predicted: FVC can reveal if caused by obstruction

SPIROMETRY

VC: Significance/Pathophysiology 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 Acceptability3. 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 Acceptability4. Three acceptable spirograms obtained; two

largest FVC values within 150 ml; two largest FEV1 values within 150 ml

SPIROMETRY

FVC: Selection CriteriaThe 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 Forced Expiratory Volume (FEV1)

May be reduced in obstructive or restrictive patterns, or poor patient effort


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


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


FEV1 may be reduced in restrictive lung processes

Fibrosis Edema Space-occupying lesions Neuromuscular diseases Obesity Chest wall deformity


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


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 Ratio (FEVT%)

FEVT% = FEVT/FVC x 100 Useful in distinguishing between

obstructive and restrictive causes of reduced FEV1 values


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 Patients with obstructive disease have reduced FEVreduced FEVT%T% for each interval for each interval


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

FEV1/FVC <75%


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

MVVDecreased in:

Patients with moderate to severe obstructive lung disease

Patients who are weak or have decreased endurance

Patients with neurological deficits

SPIROMETRY

MVVDecreased 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

Before/After Bronchodilator 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 steroidsInhaled steroids Maintain dosage Maintain dosage

SPIROMETRY

Before/After Bronchodilator 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

Before/After Bronchodilator 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

Before/After BronchodilatorSignificance and Pathophysiology

Considered significant if: FEV1 or FVC increase ≥12% and ≥200 ml

SGaw increases 30% - 40%

SPIROMETRY

Before/After BronchodilatorSignificance and Pathophysiology

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

Before/After BronchodilatorSignificance and Pathophysiology 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

Maximal Inspiratory Pressure (MIP)

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

Primarily measures inspiratory muscle strength

SPIROMETRY

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) The most negative value from at

least 3 efforts that vary less than 20% is recorded

SPIROMETRY

MIP

SPIROMETRY

MIPSignificance and Pathophysiology Healthy adults greater than

-50 cm H2O (women) -75 cm H2O (men)

Decreased in patients with:Neuromuscular diseaseDiseases involving the diaphragm, intercostal, or accessory musclesHyperinflation (emphysema)

SPIROMETRY

MIPSignificance and Pathophysiology Sometimes used to measure

response to respiratory muscle training

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

SPIROMETRY

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

SPIROMETRY

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 (e.g., 80 cm H20)

SPIROMETRY

MIP and MEP

SPIROMETRY

MEPSignificance and Pathophysiology

Healthy adults >80 (women) >100 (men)

Decreased in: Neuromuscular disorders High cervical spine fractures Damage to nerves controlling abdominal

and accessory muscles of expiration

SPIROMETRY

MEPSignificance and Pathophysiology A low MEP is associated with

inability to cough May complicate chronic bronchitis,

cystic fibrosis, and other diseases that result in excessive mucus production

SPIROMETRY

Airway Resistance (Raw)

The pressure difference per unit of flow as gas flows in or out of the lungs

Recorded in cm H2O/L/sec When related to lung volume at the

time of measurement it is known as specific airway resistance (SRaw)specific airway resistance (SRaw)

SPIROMETRY

Raw

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

SPIROMETRYFlow is measured directly by means of the pneumotachometer. As the patient pants with the shutter open, flow is plotted against boxy pressure (V/PBOX) as an S-shaped curve on the computer display. A shutter occludes the airway momentarily, usually at end-expiration, and a sloping line representing the ration of mouth pressure to boxy pressure (PMOUTH/PBOX) is recorded. Airway resistance is then calculated as the ratio of these tow tangents using appropriate calibration factors.

SPIROMETRY

Raw

SPIROMETRY

Raw Criteria of Acceptability

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

SPIROMETRY


Normal Adult Values

Raw 0.6 – 2.4 cm H2O/L/sec

SRaw 0.190 – 0.667 cm H2O/L/sec/L

SPIROMETRY


May be increased in:

Bronchospasm Inflammation Mucus secretion Airway collapse Lesions obstructing the larger airways

Tumors, traumatic injuries, foreign bodies

SPIROMETRY

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

SPIROMETRY

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)

SPIROMETRY

Gaw

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

SPIROMETRY

Gaw Criteria of Acceptability

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

SPIROMETRY


Normal Adult Values

Gaw 0.42 – 1.67 L/sec/cmH2O

SGaw 0.15 – 0.20 L/sec/cm H2O/L

SPIROMETRY


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:

ActualPredicted %Predicted FVC 4.01 L4.97 L81 FEV1 2.58 L3.67 L56 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 %PredictedFVC3.75 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

Documents

lung volume testing

lung tissuespirometryvc

maximal inspiration

flowvolume curvesdetermine

acceptable maneuvers

appropriate fvc

actual value

forced effort