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Danish Thameem M.D. Pulmonary and Critical Care Medicine.

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Presentation on theme: "Danish Thameem M.D. Pulmonary and Critical Care Medicine."— Presentation transcript:

1 Danish Thameem M.D. Pulmonary and Critical Care Medicine

2 Indications for Pulmonary Functions Evaluation of a pulmonary symptom Evaluation of smokers without symptoms Evaluation of workers exposed to hazards Quantification of impairment Evaluate response to therapy Preoperative assessment Disability evaluation

3 Timeline of cigarette smokers that develop obstructive lung disease.

4 Types of Pulmonary Function Tests Spirometry Lung Volumes Diffusion Capacity Maximal Respiratory Pressures Maximum Voluntary Ventilation (MVV) Arterial Blood Gases Pulse Oximetry Bronchoprovocation

5 Lung Volumes Diagram

6 Lung Volumes and Capacities Four Volumes V T IRV ERV RV Four Capacities VC IC FRC TLC

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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?

9 Acceptability Criteria for Spirograms Free from artifacts Cough or glottis closure during the first second of exhalation Early termination or cutoff Variable effort Leak Obstructed mouthpiece Satisfactory exhalation 6 sec of exhalation and/or a plateau in the volume-time curve or Reasonable duration or a plateau in the volume-time curve or The subject cannot or should not continue to exhale

10 Are the two largest FVCs within 0.2 L of each other? Are the two largest FEV 1 s 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 or A total of eight tests have been performed or Save a minimum of three best maneuvers Repeatability Criteria After three acceptable spirograms have been obtained, apply the following tests

11 Spirometry FVC (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 inspiration FEV1/FVC: FEV1 expressed as a % of FVC, a clinically useful index of airflow limitation

12 Spirogram

13 Predicting Normal Values Depend on patients Height Age Gender Racial & ethnic background Weight & 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 Ranges FVC % FEV % FEV 1 /FVC >0.70 of predicted ratio

15 Obstruction vs. Restriction If the FVC and / or FEV 1 is below normal The distinction between obstruction & restriction is based on the FEV 1 /FVC ratio NIH/WHO - GOLD guidelines recommends using ratio below 0.70 for the diagnosis of COPD

16 Obstructive Lung Disease Emphysema & Chronic Bronchitis Cystic Fibrosis Asthma Bronchiectasis Some Interstitial Lung Disease: (combined)

17 Restrictive Pattern Normal or elevated FEV 1 /FVC ratio With a low FEV 1 or FVC suggests restriction Lung Volumes are needed to confirm Some patients with Asthma or COPD may have this pattern (pseudorestriction)

18 Restrictive Lung Disease

19 Rating of Severity May be based on statements such as from the American Thoracic Society (ATS) Obstructive Pattern - FEV 1 Restrictive Pattern – TLC (lung volumes) If lung volumes not obtained - FVC

20 ATS/ERS Standardization of Lung Function Testing: Interpretative Strategies for lung function testsInterpretative Strategies for lung function tests

21 Classification of COPD by Severity GOLD Guidelines I: Mild FEV1/FVC 80% predicted II: 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 onset Albuterol Levalbuterol Increase FEV 1 or FVC from baseline By at least 12% By at least 200 mL Both values must be met

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24 Normal

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26 Upper Airway Obstruction Patterns Detect obstructive lesions in the major airways. Characterizes the lesion: Location of the lesion: Intrathoracic Extrathoracic Behavior of the lesion in rapid inspiration and expiration: Fixed Variable

27 Variable Extrathoracic Obstruction Levitzky MG Pulmonary Physiology, McGraw Hill 4th ed, 1995, p 50 Vocal cord paralysis Goiter Tumor

28 Variable Intrathoracic Obstruction Levitzky MG Pulmonary Physiology, McGraw Hill 4th ed, 1995, p 50 Tracheomalacia Intratracheal tumor

29 Fixed Obstruction Levitzky MG Pulmonary Physiology, McGraw Hill 4th ed, 1995, p 50 Tracheal stenosis/stricture Bilateral vocal cord paralysis Extrinsic compression

30 Lung Volumes

31 Lung Volumes Diagram

32 Lung Volumes in Lung Diseases

33 Diffusion Capacity Estimates 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 pressure 4) Hemoglobin 5) Carboxyhemoglobin

34 Diffusing Capacity Single-breath DLCO measures the capacity of the lung to transfer gas Patient 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 transfer Loss 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 : 56 TLC 98% RV : 156% DLCO : 30%

38 Diagnosis Very severe obstructive defect Severe reduction in DLCO High RV Air trapping COPD

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 Diagnosis Severe restriction without significant response to bronchodilators Severe reduction in DLCO ILD PULMONARY FIBROSIS

41 CASE 3 45 y/o female with history of allergic rhinitis and dyspnea on exertion FEV (70%) pre, 4.5 (100%) post BD FVC (70%) pre, 6.0 (85%) post BD RATIO - 65% pre and 75% post TLC - 6 L (100%) DLCO - 100%

42 Diagnosis Mild obstruction with significant response to bronchodilators (normal) Normal lung volumes and DLCO ASTHMA

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 Normal spirometry Truncated inspiratory limb of the flow volume loop EXTRATHORACIC OBSTRUCTION

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