Presentation on theme: "Pulmonary Function Testing"— Presentation transcript:
1 Pulmonary Function Testing Danish Thameem M.D.Pulmonary and Critical Care Medicine
2 Indications for Pulmonary Functions Evaluation of a pulmonary symptomEvaluation of smokers without symptomsEvaluation of workers exposed to hazardsQuantification of impairmentEvaluate response to therapyPreoperative assessmentDisability evaluation
3 Timeline of cigarette smokers that develop obstructive lung disease.
4 Types of Pulmonary Function Tests SpirometryLung VolumesDiffusion CapacityMaximal Respiratory PressuresMaximum Voluntary Ventilation (MVV)Arterial Blood GasesPulse OximetryBronchoprovocationEvaluate gas exchange – diffusion capacity and abg.
5 Lung Volumes DiagramVolume if cannot be broken down in smaller subcomponents.
6 Lung Volumes and Capacities Four VolumesVTIRVERVRVFour CapacitiesVCICFRCTLC
8 General Approach to Interpretation Is the test interpretable?Are the results normal? Or abnormal?What is the pattern?What is the severity?What does this mean for the patient?PFT’s cannot make a diagnosis; however, patterns can help narrow differential diagnosis.
9 Acceptability Criteria for Spirograms Free from artifactsCough or glottis closure during the first second of exhalationEarly termination or cutoffVariable effortLeakObstructed mouthpieceSatisfactory exhalation6 sec of exhalation and/or a plateau in the volume-time curve orReasonable duration or a plateau in the volume-time curve orThe subject cannot or should not continue to exhaleGood startExtrapolated volume is <5% of FVC or 0.15 L, whichever is greater orTime to PEF is <120 ms (optional until further information is available)
10 Repeatability Criteria After three acceptable spirograms have been obtained, apply the following testsAre the two largest FVCs within 0.2 L of each other?Are the two largest FEV1s within 0.2 L of each other?If both of these criteria are met, the test session may be concluded. If both of these criteria are not met, continue testing until: Both of the criteria are met with analysis of additional acceptable spirograms orA total of eight tests have been performed orSave a minimum of three best maneuvers
11 SpirometryFVC (forced vital capacity): maximum volume of air that can be exhaled during a forced maneuver (after maximal forced inspiration, TLC)FEV1 (forced expired volume in one second): volume expired in the first second of maximal expiration after a maximal inspirationFEV1/FVC: FEV1 expressed as a % of FVC, aclinically useful index of airflow limitation
13 Predicting Normal Values Depend on patient’sHeightAgeGenderRacial & ethnic backgroundWeight & BMI (to a lesser degree)Reference Standards
14 Percent Predicted as Normal Range Results are expressed as % Predicted of a predicted normal value of a person the same age, sex, and height. (FVC and FEV1)Normal RangesFVC %FEV %FEV1/FVC >0.70 of predicted ratio
15 Obstruction vs. Restriction If the FVC and / or FEV1 is below normalThe distinction between obstruction & restriction is based on the FEV1/FVC ratioNIH/WHO - GOLD guidelines recommends using ratio below 0.70 for the diagnosis of COPDATS – FEV1/FVC ratio 0.08 to 0.10 less than the predicted ratio.
17 Restrictive Pattern Normal or elevated FEV1/FVC ratio With a low FEV1 or FVC suggests restrictionLung Volumes are needed to confirmSome patients with Asthma or COPD may have this pattern (“pseudorestriction”)
19 Rating of SeverityMay be based on statements such as from the American Thoracic Society (ATS)Obstructive Pattern - FEV1Restrictive Pattern – TLC (lung volumes)If lung volumes not obtained - FVC
20 ATS/ERS Standardization of Lung Function Testing: Interpretative Strategies for lung function tests
21 Classification of COPD by Severity GOLD Guidelines - 2009 I: Mild FEV1/FVC < 70%; FEV1 > 80% predictedII: Moderate FEV1/FVC < 70%; 50% < FEV1 < 80%III: Severe FEV1/FVC < 70%; 30% < FEV1 <50%IV: Very FEV1/FVC < 70%; FEV1 < 30% predicted Severe or FEV1 < 50% predicted plus chronic respiratory failure
22 Bronchodilator Response Must use bronchodilator with rapid onsetAlbuterolLevalbuterolIncrease FEV1 or FVC from baselineBy at least 12%By at least 200 mLBoth values must be metHelp differentiate between asthma and copd. If not responsive does not mean not to use bronchodilators.
26 Upper Airway Obstruction Patterns Detect obstructive lesions in the major airways.Characterizes the lesion:Location of the lesion:IntrathoracicExtrathoracicBehavior of the lesion in rapid inspiration and expiration:FixedVariableUncommon. Suspicion based on FVL. Different from obstruction of more distal airways due to asthma and COPD.
27 Variable Extrathoracic Obstruction Extrathoracic - above the suprasternal notch.Effects of forced expiration and inspiration in dynamic extrathoracic airway obstruction. Left, during forced expiration, intratracheal pressure (Ptr) exceeds the pressure around the airway (Patm), lessening the obstruction. Right, during forced inspiration, when intratracheal pressure falls below the atmospheric pressure, the obstruction worsens resulting in flow limitation.Vocal cord paralysisGoiterTumorLevitzky MG Pulmonary Physiology, McGraw Hill 4th ed, 1995, p 50
28 Variable Intrathoracic Obstruction Lesion is within the thoracic cavity – below suprasternal notch.Left panel, during forced expiration, the intrathoracic intratracheal pressure (Ptr) is less than the pressure in the pleural pressure (Ppl), worsening the obstruction. Right, during forced inspiration, intratracheal pressure exceeds the pleural pressure, lessening the degree of obstruction.TracheomalaciaIntratracheal tumorLevitzky MG Pulmonary Physiology, McGraw Hill 4th ed, 1995, p 50
29 Fixed Obstruction Tracheal stenosis/stricture Bilateral vocal cord paralysisExtrinsic compressionLevitzky MG Pulmonary Physiology, McGraw Hill 4th ed, 1995, p 50
33 Diffusion CapacityEstimates the transfer of oxygen in the alveolar air to the red blood cell.Factors that influence the diffusion:1) Area of the alveolar-capillary membrane (A)2) Thickness of the membrane (T)3) Driving pressure4) Hemoglobin5) Carboxyhemoglobin
34 Diffusing CapacitySingle-breath DLCO measures the capacity of the lung to transfer gasPatient exhales to RV then rapidly inhales gas mixture with minute amount of CO. After, 10 second breath-hold at TLC, the patient rapidly exhales & the exhaled gas is analyzed to measure the amount of CO transferred into the capillary blood during the maneuver
35 Abnormalities of Diffusing Capacity Decreased in conditions that disrupt the alveolar-capillary surface for gas transferLoss of surface area (resection, fibrosis, emphysema, pneumonia)Reduced lung capillary volume (vasculitis, thromboembolism, primary pulm htn, ILD)Increased diffusion distance (PAP, PCP)
36 Abnormalities of Diffusing Capacity Increased by conditions that lead to recruitment of pulmonary vascular bed and increase in capillary blood volume(exercise, mild CHF, asthma)Or by increased amount of hemoglobin which binds CO(pulmonary hemorrhage, erythrocytosis)
37 CASE 1 54 y/o male smoker PFT FEV1 : 1.3 L (23%) FVC : 2.3 L (45%) FEV1/FVC : 56TLC 98%RV : 156%DLCO : 30%
38 COPD Diagnosis Very severe obstructive defect Severe reduction in DLCO High RVAir trappingCOPD
39 CASE 2 35 y/o F with SLE FEV1 : (56%) FVC : (45%) FEV1/FVC 90 TLC : 48%RV: 45%DLCO : 23%FEV1 increased by 4% (0.1 L) with bronchodilator testing
40 DiagnosisSevere restriction without significant response to bronchodilatorsSevere reduction in DLCOILDPULMONARY FIBROSIS
41 CASE 345 y/o female with history of allergic rhinitis and dyspnea on exertionFEV (70%) pre, 4.5 (100%) post BDFVC (70%) pre, 6.0 (85%) post BDRATIO - 65% pre and 75% postTLC - 6 L (100%)DLCO - 100%
42 DiagnosisMild obstruction with significant response to bronchodilators (normal)Normal lung volumes and DLCOASTHMA
43 CASE 4 76 y/o male with weight loss and dyspnea FEV1 - 4 L ( 85%) FVC L (80%)RATIO - 78%TLC - 6 L ( 82%)DLCO - 88%
44 Diagnosis EXTRATHORACIC OBSTRUCTION Normal spirometry Truncated inspiratory limb of the flow volume loopEXTRATHORACIC OBSTRUCTION
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