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1 Pulmonary Function Tests Wanida Paoin. 2 Objectives Review basic pulmonary anatomy and lung volume. Indication for PFTs. Technique and basic interpretation.

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Presentation on theme: "1 Pulmonary Function Tests Wanida Paoin. 2 Objectives Review basic pulmonary anatomy and lung volume. Indication for PFTs. Technique and basic interpretation."— Presentation transcript:

1 1 Pulmonary Function Tests Wanida Paoin

2 2 Objectives Review basic pulmonary anatomy and lung volume. Indication for PFTs. Technique and basic interpretation of spirometry. Difference between obstructive and restrictive lung disease. Clinically application

3 3 Conducting Airways Air travels via laminar flow through the conducting airways: trachea, lobar bronchi, segmental bronchi, subsegmental bronchi, small bronchi, bronchioles, and terminal bronchioles.

4 4 From Netter Atlas of Human Anatomy, 1989

5 5 Gas Exchange Capillaries are wrapped around alveoli. Approximately 300 million alveoli Alveolar-capillary barrier: 0.3 μm in some places, surface area of square meters! (size of a tennis court) Murray & Nadel: Textbook of Respiratory Medicine, 3rd ed., Copyright © 2000 W. B. Saunders Company

6 6 Lung Volumes IRV ERV 4 Volumes 4 Capacities Sum of 2 or more lung volumes RV IC FRC VC TLC RV TV

7 7 Pulmonary Function Tests Pulse oximetry Blood gases End tidal CO 2 Spirometry Peak expiratory flow rate Bronchial challenge testing Exercise tests Respiratory muscle pressure measurement Lung volumes by helium dilution or body plethysmography Diffusing capacity

8 8 Pulmonary Function Tests Evaluates 1 or more major aspects of the respiratory system Lung volumes Airway function Gas exchange

9 9 Indications Detect disease Evaluate extent and monitor course of disease Evaluate treatment Measure effects of exposures Assess risk for surgical procedures Assess bronchial hyperreactivity

10 10 Evaluate extent and monitor course of disease Obstructive disease - asthma - FB - subglottic, tracheal stenosis - tracheomalacia - vascular ring - vocal cord paralysis

11 11 Evaluate extent and monitor course of disease Restictive disease - external compression: thoracic cage abnormality, pleural effusion, pneumothorax, obesity, scoliosis - unexpanded lung: interstitial fibrosis, pulmonary edema - neuromuscular disease: poliomyelitis, myasthenia grevis

12 12 Importance Patients and physicians have inaccurate perceptions of severity of airflow obstruction and/or severity of lung disease by physical exam Provides objective evidence in identifying patterns of disease

13 13 Spirometry Measurement of the pattern of air movement into and out of the lungs during controlled ventilatory maneuvers. Silhouette of Hutchinson Performing Spirometry, From Chest, 2002

14 14 Limitation They do not act alone. They act only to support or exclude a diagnosis.

15 15 Mechanical Properties Compliance Describes the stiffness of the lungs volume / pressure Elastic recoil The tendency of the lung to return to it’s resting state A lung that is fully stretched has more elastic recoil and thus larger maximal flows

16 16 Resistive Properties Determined by airway caliber Affected by Lung volume Bronchial smooth muscles Airway collapsibility

17 17 Factors That Affect Lung Volumes Age Sex Height Weight Race Disease

18 18 Special Considerations Ability to perform spirometry dependent on developmental age of child, personality, and interest of the child. Patients need a calm, relaxed environment and good coaching. Patience is key. Even with the best of environments and coaching, a child may not be able to perform spirometry.

19 19 Parameter from spirometer Flow-Volume Curve Spirogram FVC FEV 1 FEF PEFR

20 20 Technique Give instructions and demonstrate Patient performs the maneuver Sit / Stand direct Puts nose clip on Inhales maximally Puts mouthpiece on mouth and closes lips around mouthpiece Exhales as hard and fast and long as possible Repeat minimum of three times (check for reproducibility.) Use the best value for interpretation as %predicted of control (age, height, sex, race) (adapted from ATS, 1994) Acceptable criteria  3 min  > 10 y: > 6 min  or no more volume > 1 min  Not inhale  No air leak  No pause 2 maximum FVC different < 10%

21 21 FVC Forced vital capacity (FVC): Total volume of air that can be exhaled forcefully from TLC The majority of FVC can be exhaled in <3 seconds in normal people, but often is much more prolonged in obstructive diseases

22 22 Forced expiratory volume in 1 second: (FEV 1 ) Volume of air forcefully expired from full inflation (TLC) in the first second Normal people can exhale more than 80% of their FVC in the first second (FEV 1 /FVC) FEV 1

23 23 Forced expiratory flow % (FEF ) Mean forced expiratory flow during middle half of FVC May reflect effort independent expiration and the status of the small airways Highly variable Depends heavily on FVC FEF 25-75

24 24 PEFR

25 25 PEFR Peak flow meter device Technique Sit/Stand direct Inhales maximally Puts mouthpiece on mouth and closes lips around mouthpiece Blow out as hard and fast as possible Repeat minimum of three times Use the best value for interpretation as %predicted / personal best Clinical application: monitor severity, daily variability, pre and post bronchodilator Green : > 80% Yellow : 50-79% Red : < 50% Normal < 20% Normal < 12%

26 26 Categories of Disease Obstructive Restrictive Mixed

27 27 FVC Interpretation of % predicted: 80 %Normal 70-79%Mild reduction 50%-69%Moderate reduction <50%Severe reduction

28 28 FEV 1 Interpretation of % predicted: >80%Normal 65-79%Mild obstruction 50-64%Moderate obstruction <49%Severe obstruction

29 29 Spirometry Interpretation: % predicted FVC> 80% FEV1> 80% FEF 25-75% > 70% PEFR> 80% FEV 1 /FVC> 80% absolute value

30 30 Spirometry in Obstructive Disease Slow rise in upstroke May not reach plateau

31 31 Restrictive Disease Rapid upstroke as in normal spirometry Plateau volume is low

32 32 Spirometry Interpretation: Obstructive vs. Restrictive Defect ParameterObstructive Disorders Restrictive Disorders FVC FEV 1 FEF 25-75% FEV1/FVC PEFR N or ↓ ↓ ↓ ↓ N to ↓ ↓ N or ↑ ↓ N to ↓ What parameter is the most sensitive in airway obstruction?

33 33 Spirometry Interpretation: Obstructive Disorders Characterized by a limitation of expiratory airflow Examples: Asthma Bronchiectasis COPD Cystic Fibrosis Restrictive Disorders Characterized by reduced lung volumes/decreased lung compliance Examples: Interstitial Fibrosis Kyphoscoliosis Obesity Lung Resection Neuromuscular diseases Cystic Fibrosis

34 34 Flow-Volume Loop Ruppel GL. Manual of Pulmonary Function Testing, 8 th ed., Mosby 2003 Do FVC maneuver and then inhale as rapidly and as much as able. The expiratory and inspiratory flow volume curves put together make a flow volume loop. RV TLC PEFR flow volume expiration inspiration

35 35 Restrictive Lung Disease Characterized by diminished lung volume Decreased TLC, FVC Normal or increased: FEV 1 /FVC ratio

36 36 Obstructive Lung Disease Characterized by a limitation of expiratory airflow Examples: asthma, COPD

37 37 Large Airway Obstruction Characterized by a truncated inspiratory or expiratory loop

38 38 (Rudolph and Rudolph, 2003) Flow-Volume Loops Variable intrathoracic ob Fixed central or up aw ob Inadq effort Incomplete exhalation Variable extrathoracic ob Restrictive lung disease L1 L2 L3 L4 R2 R3 R1

39 39 Spirometry: Pre and Post Bronchodilator Obtain spirogram and flow-volume loop. Pre and 15 minutes after administration of the bronchodilator Salbutamol MDI 4 puffs via valve spacer Slow inhale Breath hold 5-10 sec sec pause between each puff. Reversibility: FEV 1 / PEFR > 12% Improve flow-volume loop.

40 40 PEFR Inhales maximally Exhales as hard and fast and short as possible Repeat minimum of three times Use the best value for interpretation as %predicted of control / personal best Highly effort dependent Diurnal variation (normal < 20%) Different value in each devices

41 41 Exercise challenge test Perform spirometry Exercise 6-8 min (tread mill) till HR /min Repeat spirometry at 5, 10, 15, 20, 30 min EIB: FEV %, or wheezing

42 42 Respiratory muscle testing Measure maximum inspiratory P. (PImax, MIP) or negative inspiratory force (NIF) Maximum inhale via pressure manometer Normal < -60 cmH 2 O Useful for evaluation neuromuscular dis: myasthenia grevis, Guillian-Barre syndrome, diaphragmatic paralysis, pre-extubation Other parameter: FVC, PEFR

43 43 Clinical Applications

44 44 Case #1 ParameterActual%Predicted FVC (L) FEV 1 (L) FEV1/FVC (%)8093 FEF 25-75% (L/s) PEFR (L/s) Case #1

45 45 Case #2 ParameterActual (best)Predicted%Predicted FVC (L) FEV 1 (L) FEV1/FVC (%) FEF 25-75% (L/s) PEFR (L/s)

46 46 Case #3 ParameterActual (best)Predicted%Predicted FVC (L) FEV 1 (L) FEV 1 /FVC (%) FEF 25-75% (L/s) PEFR (L/s)

47 47 Case #4 ParameterActual (best)Predicted%Predicted FVC (L) FEV 1 (L) FEV 1 /FVC (%) FEF 25-75% (L/s) PEFR (L/s)

48 48 Case #5 ParameterPre%PredPost%Pred %Change FVC (L) FEV 1 (L) FEV 1 /FVC FEF 25-75% PEFR (L/s)


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