Spirometry and Related Tests

Name: Spirometry and Related Tests
Uploaded: 2017-07-18T05:47:53+00:00
Duration: PTM38S51
Channel: Judith Tate
Description: Spirometry and Related Tests

Spirometry and Related Tests
RET 2414 Pulmonary Function Testing Module 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 Laboratory Normal Ranges

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

PFT Reports When performing PFT’s three values are reported:
Actual – what the patient performed Predicted – what the patient should have performed based on Age, Height, Sex, Weight, and Ethnicity % Predicted – a comparison of the actual value to the predicted value

PFT Reports Example Actual Predicted %Predicted VC %

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 Example: Valid VC measurements important
IC and ERV used to calculate RV and TLC Example: RV = FRC - ERV TLC = IC + FRC

SPIROMETRY VC: Criteria for Acceptability
End-expiratory volume varies by less than 100 ml for three preceding breaths Volume plateau observed at maximal inspiration and expiration

SPIROMETRY VC: Criteria for Acceptability
Three acceptable VC maneuvers should be obtained; volume within 150 ml. VC should be within 150 ml of FVC value

SPIROMETRY VC: Selection Criteria
The 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

Obstructive lung disease Respiratory depression or neuromuscular disease Pleural effusion Pneumothorax Hiatal hernia Enlarged heart

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 Acceptability
Maximal effort; no cough or glottic closure during the first second; no leaks or obstruction of the mouthpiece. Good start-of-test; back extrapolated volume <5% of FVC or 150 ml, whichever is greater

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

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

FVC can be reduced by: Mucus plugging Bronchiolar narrowing Chronic or acute asthma Bronchiectasis Cystic fibrosis Trachea or mainstem bronchi obstruction

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

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

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

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 reduced FEVT% 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 measurements of PEF as a guide to treatment ATS Recommended Ranges L/min (children) 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 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

An FEV1% less than predicted is a good indication for bronchodilator study In most patients, an FEV1% less than 70% indicates obstruction

Any pulmonary function parameter may be measured before and after bronchodilator therapy FEV1 and specific airway conductance (SGaw) are usually evaluated

Lung volumes should be recorded before bronchodilator administration Lung volumes and DLco may also respond to bronchodilator therapy

Routine bronchodilator therapy should be withheld prior to spirometry Ruppel 9th edition, pg. 66: Table 2-2 Short-acting β-agonists hours Short-acting anticholinergic 4 hours Long-acting β-agonists hours Long-acting anticholinergic 24 hours Methylxanthines (theophyllines) 12 hours Slow release methylxanthines 24 hours Cromolyn sodium hours Leukotriene modifiers 24 hours Inhaled steroids Maintain dosage

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

Percentage of change is calculated %Change = Postdrug – Predrug X 100 Predrug

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

Significance and Pathophysiology Considered significant if: FEV1 or FVC increase ≥12% and ≥200 ml SGaw increases 30% - 40%

Significance 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

Significance 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)

SPIROMETRY MIP

Significance and Pathophysiology
SPIROMETRY MIP Significance and Pathophysiology Healthy adults > -60 cm H2O Decreased in patients with: Neuromuscular disease Diseases involving the diaphragm, intercostal, or accessory muscles Hyperinflation (emphysema)

SPIROMETRY MIP Significance 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

SPIROMETRY MIP and MEP

SPIROMETRY MEP Significance and Pathophysiology Healthy adults >80 to 100 cm H2O Decreased in: Neuromuscular disorders High cervical spine fractures Damage to nerves controlling abdominal and accessory muscles of inspiration

SPIROMETRY MEP Significance 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 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)

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

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

SPIROMETRY Airway Resistance (Raw) Normal Adult Values
Raw – 2.4 cm H2O/L/sec SRaw – cm H2O/L/sec/L

SPIROMETRY Airway Resistance (Raw) May be increased in: Bronchospasm
Inflammation Mucus secretion Airway collapse Lesions obstructing the larger airways Tumors, traumatic injuries, foreign bodies

SPIROMETRY Raw Significance 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 Airway Conductance (Gaw) Normal Adult Values
Gaw – 1.67 L/sec/cmH2O SGaw – 0.20 L/sec/cm H2O/L

SPIROMETRY Airway Conductance (Gaw) 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. False Only for those individuals with lung disease This applies only to cigarette smokers True

Quiz Practice Vital capacity is defined as which of the following?
The volume of gas measured from a slow, complete exhalation after a maximal inspiration, without a forced effort The volume of gas measured from a rapid, complete exhalation after a rapid maximal inspiration The volume of gas measured after 3 seconds of a slow, complete exhalation 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? End-expiratory volume varies by less than 100 ml for three preceding breaths Volume plateau observed at maximal inspiration and expiration Three acceptable vital capacity maneuvers should be obtained; volume within 150 ml Vital capacity should be within 150 ml of forced vital capacity in healthy individuals I, II, and IV II, III, and IV III and IV I, II, III, IV

Quiz Practice Which of the following best describes the Forced Vital Capacity (FVC) maneuver? The volume of gas measured from a slow, complete exhalation after a maximal inspiration, without a forced effort The volume of gas measured from a slow, complete exhalation after a rapid maximal inspiration The volume of gas measured after 3 seconds of a rapid, complete exhalation 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? Maximal effort, no cough or glottic closure during the first second; no leaks of obstruction of the mouthpiece Good start of test; back extrapolated volume less than 5% of the FVC or 150 ml Tracing shows a minimum of 3 seconds of exhalation 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. True False Only when done slowly Only when divided by the FVC

Quiz Practice Which of following statements is true regarding FEV1?
FEV1 may be larger than the FVC FEV1 is always 75% of FVC May be reduced in obstructive and restrictive lung disease Is only reduced in restrictive disease

Quiz Practice The FEV1% is useful in distinguishing between obstructive and restrictive causes of reduced FEV1 values True False Only helps to distinguish obstructive lung disease Only helps to distinguish restrictive lung disease

Quiz Practice Which statements are true regarding the FEV 1%, also known as the FEV1/FVC? A decreased FEV1/FVC is the hallmark of obstructive disease Patients with restrictive lung disease often have normal or increased FEV1/FVC ratios The presence of a restrictive disorder may be suggested by a reduced FVC and a normal or increased FEV1/FVC ratio A normal FEV1/FVC ratio is between 75% - 85% I and II I, II and III II, III and IV I, II, III and IV

Quiz Practice What test is represented by the graph to the right?
Forced Vital Capacity Flow-Volume Loop Slow Vital Capacity Total Lung Capacity Maneuver

Quiz Practice What type of pulmonary disorder is represented by the graph below? Obstructive lung disease Restrictive lung disease Upper airway obstruction Normal lung function (The dotted lines represent the predicted values)

Quiz Practice Which is true regarding Peak Expiratory Flow (PEF)?
Primarily measures large airway function Is a recognized means of monitoring asthma Serial measurements of PEF are used a guide to treat asthma When less than 50% of personal best, it is an indication that immediate treatment is required I only II and III II, III, and IV I, II, III, and IV

Quiz Practice MVV is decreased in patients with which of the following disorders? Moderate to severe obstructive lung disease Weak or with decrease endurance Neurological defects Paralysis or nerve damage I and IV II and III III and IV I, II, III, and IV

Quiz Practice Spirometry before and after bronchodilator therapy is used to determine which of the following? Reversibility of airway obstruction The severity of restrictive disorders The rate at which CO diffuses through the lung into the blood 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? 5 minutes 10 minutes 30 minutes 60 minute

Quiz Practice Bronchodilation is considered significant when which of the following occurs? FEV1/FVC increases by 12% SGaw increases by 12% FVC and/or FEV1 increases by 12% and 150 ml DLco increases by 12%

Quiz Practice Which of the following is true regarding Maximal Inspiratory Pressure (MIP)? Primarily measures inspiratory muscle strength Measures airway resistance during inspiration Is decreased in patients with neurological disease Often used in the assessment of respiratory muscle function in patients who need ventilatory support I, II, and III I, III, and IV II and III 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. True False Only in patients with COPD Only in patients with restrictive disorders

Quiz Practice Airway resistance may be increased in which of the following patients? Purely restrictive lung disorders Acute asthmatic episodes Mucus secretion Lung compliance changes I only I and IV II and III I, II, III, and IV

Quiz Practice Airway Conductance (Gaw) is a measure of flow that is generated from the available drive pressure. True False Only in patients with COPD Only in patients with restrictive disorders

Quiz Practice A patient’s pulmonary function tests reveal the following: Actual Predicted %Predicted FVC 4.01 L L 81 FEV L L 56 FEV1% 51 >75 _ Select the correct interpretation Restrictive pattern Obstructive pattern Inconclusive Normal

Quiz Practice A patient’s pulmonary function tests reveal the following: Actual Predicted %Predicted FVC L L 75 FEV L L 76 FEV1% 75 >/=75 _ Select the correct interpretation Restrictive pattern Obstructive pattern Inconclusive Normal

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