Pulmonary Function Test (Spirometry)

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Includes Spirometry, Peak flow Meter, Exercise Test in detail.


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Pulmonary Function Tests:

Pulmonary Function Tests Prof. AKM Mosharraf Hossain , PhD Respiratory Medicine Wing Department of Medicine BSMMU 4/13/2013 1

Types of PFT:

Types of PFT Peak flow meter 2. Spirometry 3. Measurement of lung volumes-Plethismography 4. Gas transfer factor 5. Exercise test- 6 min walk test, ergometer test 6. ABG 4/13/2013 2 The major types of pulmonary function tests (PFTs) include spirometry , lung volumes, and diffusing capacity.

PFT Indications:

PFT Indications Evaluation of symptoms such as chronic persistent cough, wheezing, dyspnea , and exertional cough or chest pain Objective assessment of bronchodilator therapy Assessing the presence of disease in a patient with known risk factors, such as smoking. Evaluation of effects of exposure to dusts or chemicals at work Risk evaluation of patients prior to thoracic or upper abdominal surgery Objective assessment of impairment or disability 4/13/2013 3

PowerPoint Presentation:

Peak flow meter 2 . Spirometry 3. Measurement of lung volumes- Plethismography 4. Gas transfer factor 5. Exercise test- walk test, ergometer test 6. ABG 4/13/2013 5


PEFR The peak expiratory flow rate (PEFR, also known as peak flow) is the maximal rate that a person can exhale during a short maximal expiratory effort after a full inspiration. Monitoring the PEFR is useful for detecting changes or trends in a patient’s asthma control An individual patient's normal PEFR range is defined as 80 and 100 percent of their personal best. The personal best is generally the highest PEFR achieved during 2 wks post-treatment monitoring period 4/13/2013 6

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Peak Flow Meter Cheapest and easy 2. Home management of asthma 3. In absence of spirometer , establish, assess and monitor Bronchial asthma 4. PEF variability= (Max PEFR-Min PEFR)x100/Max PEFR; >20% is suggestive of Bronchial Asthma 4/13/2013 7

Limitations of PEFR:

Limitations of PEFR Mild airflow obstruction may be present on spirometry when the peak flow is within the normal range. Reduced peak flow measurements may be seen in both obstructive and restrictive diseases. Peak flow measurements are not sufficient to distinguish upper airway obstruction ( eg , vocal cord dysfunction) from asthma. The validity of PEF measurements depends entirely upon patient effort and technique. Home PEF monitoring is unsupervised. Peak flow meters cannot be routinely calibrated, 4/13/2013 8

Asthma Action Plan:

Asthma Action Plan GREEN (80 to 100 percent of personal best) signals "all clear". YELLOW (50 to 80 percent of personal best) signals "caution", since the airways are somewhat obstructed. RED (below 50 percent of personal best) signals "medical alert". Bronchodilator therapy should be started immediately, and the clinician should be contacted if PEFR measures do not return immediately to the yellow or green zones. 4/13/2013 12

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Types of PFT:

Types of PFT Peak flow meter 2. Spirometry 3. Measurement of lung volumes- Plethismography 4. Gas transfer factor 5. Exercise test- 6 min walk test, ergometer test 6. ABG 4/13/2013 14


Spirometry Spirometry , in which a maximal inhalation is followed by a rapid and forceful complete exhalation into a spirometer , includes measurement of FEV 1 and FVC. Spirometry is used to measure forced expiratory flow rates and volumes. The results of spirometry can be used to determine the following: Determine whether baseline airflow limitation (obstruction) is present (reduced FEV 1 /FVC ratio) Assess the reversibility of the obstructive abnormality Characterize the severity of airflow limitation For patients with normal airflow (normal FEV 1 /FVC ratio), identify a restrictive pattern as an alternate explanation for dyspnea ( eg , FVC <80 percent predicted) 4/13/2013 15

Indications of Spirometry:

Indications of Spirometry Establish diagnosis of COPD and asthma Assess severity and progression of lung diseases Screening COPD among smokers Perform pre-operative assessment Distinguish between obstruction and restriction as causes of breathlessness Screen workforces in occupational environments Assess fitness to dive Perform pre - employment screening in certain professions 4/13/2013 16

Types of Spirometers:

Types of Spirometers Bellows spirometers : Measure volume; mainly in lung function units Electronic desk top spirometers : Measure flow and volume with real time display Small hand-held spirometers : Inexpensive and quick to use but no print out 4/13/2013 17

Standard Spirometric Indicies:

Standard Spirometric Indicies FEV 1 - Forced expiratory volume in one second: The volume of air expired in the first second of the blow FVC - Forced vital capacity: The total volume of air that can be forcibly exhaled in one breath FEV 1 /FVC ratio: T he fraction of air exhaled in the first second relative to the total volume exhaled 4/13/2013 18

Additional Spirometric Indicies:

Additional Spirometric Indicies VC - Vital capacity: A volume of a full breath exhaled in the patient’s own time and not forced. Often slightly greater than the FVC, particularly in COPD FEV 6 – Forced expired volume in six seconds: Often approximates the FVC. Easier to perform in older and COPD patients but role in COPD diagnosis remains under investigation MEFR – Mid-expiratory flow rates: Derived from the mid portion of the flow volume curve but is not useful for COPD diagnosis 4/13/2013 19

Predicted Normal Values:

Predicted Normal Values Age Height Sex Ethnic Origin Affected by: 4/13/2013 21

Criteria for Normal Spirometric Values:

Criteria for Normal Spirometric Values FEV 1 : % predicted > 80% FVC: % predicted > 80% FEV 1 /FVC: > 0.7 4/13/2013 22

Normal Trace Showing FEV1 and FVC:

Normal Trace Showing FEV 1 and FVC 1 2 3 4 5 6 1 2 3 4 Volume, liters Time, seconds FVC 5 1 FEV 1 = 4L FVC = 5L FEV 1 /FVC = 0.8 4/13/2013 23

Spirometry: Obstructive Disease:

Spirometry: Obstructive Disease Volume, liters Time, seconds 5 4 3 2 1 1 2 3 4 5 6 FEV 1 = 1.8L FVC = 3.2L FEV 1 /FVC = 0.56 Normal Obstructive 4/13/2013 24

Spirometric Diagnosis of COPD :

Spirometric Diagnosis of COPD COPD is confirmed by post–bronchodilator FEV 1 /FVC < 0.7 Post-bronchodilator FEV 1 /FVC measured 15 minutes after 400µg salbutamol or equivalent 4/13/2013 27

Bronchodilator Reversibility Testing:

Bronchodilator Reversibility Testing Provides the best achievable FEV 1 (and FVC) Helps to differentiate COPD from asthma Must be interpreted with clinical history - neither asthma nor COPD are diagnosed on spirometry alone 4/13/2013 28

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Bronchodilator Reversibility Testing in COPD Preparation Tests should be performed when patients are clinically stable and free from respiratory infection Patients should not have taken: inhaled short-acting bronchodilators in the previous six hours long-acting bronchodilator in the previous 12 hours sustained-release theophylline in the previous 24 hours 4/13/2013 29

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Bronchodilator Reversibility Testing in COPD Spirometry FEV 1 should be measured (minimum twice, within 5%) before a bronchodilator is given The bronchodilator should be given by metered dose inhaler through a spacer device or by nebulizer to be certain it has been inhaled (…..continued) 4/13/2013 30

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Bronchodilator Reversibility Testing in COPD Spirometry (continued) Possible dosage protocols: 400 µg β 2 -agonist, or 80-160 µg anticholinergic , or the two combined FEV 1 should be measured again: 10-15 minutes after a short-acting b 2 -agonist 30-45 minutes after the combination 4/13/2013 31

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Bronchodilator Reversibility Testing An increase in FEV 1 that is both greater than 200 ml and 12% above the pre-bronchodilator FEV 1 (baseline value) is considered positive response. 4/13/2013 32

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Restrictive lung disease:

Restrictive lung disease The many disorders which cause reduction of lung volumes (restriction) may be divided into three groups: Intrinsic lung diseases, which cause inflammation or scarring of the lung tissue (interstitial lung disease) or fill the airspaces with exudate or debris (acute pneumonitis ) Extrinsic disorders, such as disorders of the chest wall or the pleura, which mechanically compress the lungs or limit their expansion Neuromuscular disorders, which decrease the ability of the respiratory muscles to inflate and deflate the lungs 4/13/2013 34

Criteria: Restrictive Disease:

Criteria: Restrictive Disease FEV 1: % predicted < 80% FVC: % predicted < 80% FEV 1 /FVC: > 0.7 4/13/2013 35

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Volume, liters Time, seconds FEV 1 = 1. 9 L FVC = 2 .0 L FEV 1 /FVC = 0. 95 1 2 3 4 5 6 5 4 3 2 1 Spirometry: Restrictive Disease Normal Restrictive 4/13/2013 36

Mixed Obstructive/Restrictive:

Mixed Obstructive/Restrictive FEV 1 : % predicted < 80% FVC: % predicted < 80% FEV 1 /FVC: < 0.7 4/13/2013 37

Mixed Obstructive and Restrictive:

Mixed Obstructive and Restrictive Volume, liters Time, seconds Restrictive and mixed obstructive-restrictive are difficult to diagnose by spirometry alone; full respiratory function tests are usually required ( e.g., body plethysmography, etc) FEV 1 = 0.5 L FVC = 1.5 L FEV 1 /FVC = 0. 30 Normal Obstructive - Restrictive 4/13/2013 38

Spirometry: Abnormal Patterns:

Obstructive Restrictive Mixed Time Time Time Volume Volume Volume Spirometry: Abnormal Patterns Slow rise, reduced volume expired; prolonged time to full expiration Fast rise to plateau at reduced maximum volume Slow rise to reduced maximum volume; measure static lung volumes and full P FT’s to confirm 4/13/2013 39

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SPIROMETRY Flow Volume 4/13/2013 40

Flow Volume Curve:

Flow Volume Curve Standard on most desk-top spirometers Adds more information than volume time curve Better at demonstrating mild airflow obstruction 4/13/2013 41

Flow Volume Curve:

Flow Volume Curve Expiratory flow rate L/sec Volume (L) FVC Maximum expiratory flow (PEF) Inspiratory flow rate L/sec RV TLC 4/13/2013 42

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Flow Volume Curve Patterns Obstructive and Restrictive:

Flow Volume Curve Patterns Obstructive and Restrictive Obstructive Severe obstructive Restrictive Volume (L) Expiratory flow rate Expiratory flow rate Expiratory flow rate Volume (L) Volume (L) Steeple pattern, reduced peak flow, rapid fall off Normal shape, normal peak flow, reduced volume Reduced peak flow, scooped out mid-curve 4/13/2013 46

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PRACTICAL SESSION Performing Spirometry

Withholding Medications:

Withholding Medications Before performing spirometry, withhold: Short acting β 2 -agonists for 6 hours Long acting β 2 -agonists for 12 hours Ipratropium for 6 hours Tiotropium for 24 hours Optimally, subjects should avoid caffeine and cigarette smoking for 30 minutes before performing spirometry 4/13/2013 53

Performing Spirometry - Preparation :

Performing Spirometry - Preparation Explain the purpose of the test and demonstrate the procedure Record the patient’s age, height and gender and enter on the spirometer Note when bronchodilator was last used Have the patient sitting comfortably Loosen any tight clothing Empty the bladder beforehand if needed 4/13/2013 54

Spirometry procedure:

Spirometry procedure ◊ stand or sit straight ◊ inhale maximally (breathe in all the way) ◊ get a good seal around the mouth piece ◊ blow out as hard (not blowing hard enough-apparent obstructive) and as fast as possible ◊ continue to exhale until he or she can blow no more, at least 6 secs ( stops blowing too early apparent restrictive) 4/13/2013 55

PowerPoint Presentation:

Watch the patient during the blow to assure the lips are sealed around the mouthpiece Check to determine if an adequate trace has been achieved Repeat the procedure at least twice more until ideally 3 readings within 100 ml or 5% of each other are obtained Performing Spirometry 4/13/2013 57

ATS criteria:

ATS criteria Acceptibility criteria: ◊ free from artifacts (cough or glottic closure) ◊ free from leaks ◊ Good starts, time to PEF <120 millisecs ◊ acceptable exhalation-at least 6 secs 4/13/2013 58

ATS criteria:

ATS criteria Reproducibility criteria: ◊ 3 acceptable manoeuvres ◊ 2 largest FVC with in .2 l ◊ 2 largest FEV1 with in .2l 4/13/2013 59

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Three times FVC within 5% or 0.1 litre (100 ml) Reproducibility - Quality of Results Volume, liters Time, seconds 4/13/2013 60

Spirometry - Possible Side Effects:

Spirometry - Possible Side Effects Feeling light-headed Headache Getting red in the face Fainting: reduced venous return or vasovagal attack (reflex) Tran s ient u rinary incontinence Spirometry should be avoided after recent heart attack or stroke 4/13/2013 61

Spirometry - Quality Control:

Spirometry - Quality Control Most common cause of inconsistent readings is poor patient technique Sub-optimal inspiration Sub-maximal expiratory effort Delay in forced expiration Shortened expiratory time Air leak around the mouthpiece Subjects must be observed and encouraged throughout the procedure 4/13/2013 62

Spirometry – Common Problems:

Spirometry – Common Problems Inadequate or incomplete blow Lack of blast effort during exhalation Slow start to maximal effort Lips not sealed around mouthpiece Coughing during the blow Extra breath during the blow Glottic closure or obstruction of mouthpiece by tongue or teeth Poor posture – leaning forwards 4/13/2013 63

Equipment Maintenance:

Equipment Maintenance Most spirometers need regular calibration to check accuracy Calibration is normally performed with a 3 litre syringe Some electronic spirometers do not require daily/weekly calibration Good equipment cleanliness and anti-infection control are important; Spirometers should be regularly serviced; 4/13/2013 64

Troubleshooting :

Troubleshooting Examples - Unacceptable Traces

Unacceptable Trace - Poor Effort:

Unacceptable Trace - Poor Effort Volume, liters Time, seconds May be accompanied by a slow start Inadequate sustaining of effort Variable expiratory effort Normal 4/13/2013 66

Unacceptable Trace – Stop Early:

Volume, liters Time, seconds Unacceptable Trace – Stop Early Normal 4/13/2013 67

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Unacceptable Trace – Slow Start:

Volume, liters Time, seconds Unacceptable Trace – Slow Start Normal 4/13/2013 69

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Volume, liters Time, seconds Unacceptable Trace - Coughing Normal 4/13/2013 70

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Volume, liters Time, seconds Unacceptable Trace – Extra Breath Normal 4/13/2013 71

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Spirographs Examples 4/13/2013 74

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Meas Ref %Pred FVC 2.20 2.58 85 FEVI 1.79 1.85 97 FEVI/FVC 81 72 PEF 5.67 5.20 109 Normal 4/13/2013 76

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uninterpretable 4/13/2013 77

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Small midrange flow Meas Ref %Pred FVC 2.78 2.75 101 FEVI 1.90 1.90 100 FEVI/FVC 69 69 FEF25-75 .95 2.35 40 4/13/2013 79

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Meas Ref %Pred FVC 3.66 3.54 103 FEVI 2.30 2.77 83 FEVI/FVC 63 78 PEF 2.39 6.25 38 Fixed upper airway obs 4/13/2013 80

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Meas Ref %Pred FVC 4.11 4.34 95 FEVI 3.28 3.47 94 FEVI/FVC 80 80 PEF 5.63 7.06 80 Variable extrathoracic 4/13/2013 81

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Meas Ref %Pred FVC .96 2.75 35 FEVI .94 1.90 49 FEVI/FVC 98 69 PEF 2.98 5.40 55 4/13/2013 82

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Meas Ref %Pred FVC 2.62 2.82 93 FEVI 1.45 1.98 73 FEVI/FVC 55 70 PEF 4.50 5.48 82 Mild to mod airway obs 4/13/2013 83

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Severe obstruction Meas Ref %Pred FVC 1.85 4.6 40 FEVI .92 3.33 28 FEVI/FVC 50 72 FEF25-75 .28 3.28 45 4/13/2013 84

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Meas Ref %Pred FVC 3.66 4.39 83 FEVI 1.03 2.87 36 FEVI/FVC 28 65 FEF25-75 .33 2.48 13 Severe obstruction 4/13/2013 85

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Meas Ref %Pred FVC 3.00 4.79 63 FEVI 2.54 3.28 77 FEVI/FVC 85 69 PEF 9.12 8.92 102 FEF25-75 3.25 2.97 109 Restrictive ventilatory defect 4/13/2013 86

Bronchoprovocation Test-Indications:

Bronchoprovocation Test-Indications Diagnosis of asthma: typical symptoms but normal spirometry and no response to BD; atypical symptoms eg nocturnal awakening, cough; evaluate occupational asthma, reactive airways dysfunction syndrome, or irritant-induced asthma; screening test for asthma, such as scuba divers, military personnel Assesssment of asthma therapy Identification of specific asthma triggers 4/13/2013 87

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Methacholine challenge test Generally, a methacholine PC20 of 8 mg/ mL (<4 mg/ mL , for SGaw ) or less is considered a positive test. A PC20 greater than 16 mg/ mL is considered a negative test Positive test indicates AHR, which is present mostly in Asthma, False positive MCT can occur in allergic rhinitis, cystic fibrosis, heart failure, COPD, and bronchitis. 4/13/2013 88

Lung function Tests:

Lung function Tests Peak flow meter 2. Spirometry 3. Measurement of lung volumes-Plethismography 4. Gas transfer factor 5. Exercise test- walk test, ergometer test 6. ABG 4/13/2013 92

Lung Volume Measurements:

Lung Volume Measurements Common measurements include total lung capacity (TLC), functional residual capacity (FRC), and residual volume (RV). Decreased lung volumes suggest restrictive disease if accompanied by a normal FEV 1 /FVC ratio. Increased lung volumes suggest static hyperinflation due to obstructive airways disease if accompanied by decreased FEV 1 /FVC ratio. Coexisting restriction and obstruction can be detected, but requires both spirometry and lung volumes. 4/13/2013 93

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Peak flow meter 2. Spirometry 3. Measurement of lung volumes-Plethismography 4. Gas transfer factor 5. Exercise test- walk test, ergometer test 6. ABG 4/13/2013 96


DLCO DLCO measures the ability of the lungs to transfer gas from inhaled air to the red blood cells in pulmonary capillaries. The DLCO is low in ILD,but normal in disorders of pleura,chest and neuromuscular disorder causing restrictive lung function. DLCO is also useful for following the course of or response to therapy in ILD. 4/13/2013 97

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Peak flow meter 2. Spirometry 3. Measurement of lung volumes-Plethismography 4. Gas transfer factor 5. Exercise test- walk test, ergometer test 6. ABG 4/13/2013 99

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Exercise testing with spirometry : EIB 6 MWT: provide simple, repeatable assessments of disability and response to treatment. Finally, cardiopulmonary exercise testing using cycle or treadmill exercise with measurement of metabolic gas exchange, ventilation and cardiac responses is useful in distinguishing cardiac limitation from respiratory limitation in the breathless patient . Exercise Tests uses 4/13/2013 100


6MWT The six-minute walk test (6MWT) is a good index of physical function and therapeutic response in patients with chronic lung disease, such as COPD or ILD or PAH A fall in SpO 2 of more than 4 percent (ending below 93 percent) suggests significant desaturation During a 6MWT, healthy subjects can typically walk 400 to 700 m. An improvement of more than 70 m in distance walked appears to be clinically important and noticeable to patients. Estimates of the minimum decrease in distance walked that are important to patients range from 24 to 54 m Oxygen saturation during the 6MWT can also be used to titrate the amount of oxygen needed to maintain adequate saturation during walking. 4/13/2013 101

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Exercise Challenge Test:

Exercise Challenge Test An exercise challenge test is the most direct way to establish a diagnosis of EIB. This usually involves six to eight minutes of ergometer or treadmill exercise, sufficient to raise the heart rate to 85 percent of the predicted maximum. A test is generally considered positive if the FEV1 falls by 10 percent or more, although a fall of 15 percent is more diagnostic After a baseline value has been established, FEV1 can be measured before and 2.5, 5, 10, 15, and 30 minutes after exercise and correlated with symptoms.


ABG Arterial blood gases (ABGs) may be a helpful adjunct to pulmonary function testing in selected patients. The primary role of measuring ABGs in stable outpatients is to confirm hypoventilation when it is suspected on the basis of clinical history ( eg , respiratory muscle weakness, advanced COPD), an elevated serum bicarbonate level, and/or chronic hypoxemia. ABGs also provide a more accurate assessment of the severity of hypoxemia in patients who have low normal oxyhemoglobin saturation 4/13/2013 106


OSPE Q. A 50 yrs old male, ex-smoker, presented with progressive dyspnoea . Spirometry revealed low FEV1/FVC and FEV1 low, irreversible; normal FVC and TLC. Answer to the following questions: 1) What is the diagnosis? 2) What is the most important risk factor? 3) What is the most important non-pharmacological treatment in a stable patient? 4) Mention two treatment modalities which improve exercise tolerance? 5) Name 3 surgical treatment modalities. 4/13/2013 107

OSPE-ans key:

OSPE- ans key Q. A 50 yrs old male, ex-smoker, presented with progressive dyspnoea . Spirometry revealed low FEV1/FVC and FEV1 low, irreversible; normal FVC and TLC. Answers key: 1) COPD 2) Smoking 3) Smoking cessation/avoidance of risk factor 4) Smoking cessation and LTOT 5) Bullectomy , LVRS, 4/13/2013 108

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