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 Pulmonary Function Tests Wanida Paoin
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 Conducting Airways Air travels via laminar flow through the conducting airways: trachea, lobar bronchi, segmental bronchi, subsegmental bronchi, small bronchi, bronchioles, and terminal bronchioles.
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 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 Limitation They do not act alone. They act only to support or exclude a diagnosis.
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 Resistive Properties Determined by airway caliber Affected by Lung volume Bronchial smooth muscles Airway collapsibility
17 Factors That Affect Lung Volumes Age Sex Height Weight Race Disease
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.
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 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 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 Forced expiratory flow 25- 75% (FEF 25-75 ) 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
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 Categories of Disease Obstructive Restrictive Mixed
30 Spirometry in Obstructive Disease Slow rise in upstroke May not reach plateau
31 Restrictive Disease Rapid upstroke as in normal spirometry Plateau volume is low
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 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 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 Restrictive Lung Disease Characterized by diminished lung volume Decreased TLC, FVC Normal or increased: FEV 1 /FVC ratio
36 Obstructive Lung Disease Characterized by a limitation of expiratory airflow Examples: asthma, COPD
37 Large Airway Obstruction Characterized by a truncated inspiratory or expiratory loop
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 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. 5-10 sec pause between each puff. Reversibility: FEV 1 / PEFR > 12% Improve flow-volume loop.
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 Exercise challenge test Perform spirometry Exercise 6-8 min (tread mill) till HR 160-180/min Repeat spirometry at 5, 10, 15, 20, 30 min EIB: FEV 1 10-15%, or wheezing
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 Clinical Applications
44 Case #1 ParameterActual%Predicted FVC (L)4.11116 FEV 1 (L)3.28108 FEV1/FVC (%)8093 FEF 25-75% (L/s)6.9488 PEFR (L/s)3.15107 Case #1