2Objectives 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
3Conducting AirwaysAir travels via laminar flow through the conducting airways:trachea,lobar bronchi,segmental bronchi,subsegmental bronchi,small bronchi,bronchioles, andterminal bronchioles.
12ImportancePatients and physicians have inaccurate perceptions of severity of airflow obstruction and/or severity of lung disease by physical examProvides objective evidence in identifying patterns of disease
13SpirometryMeasurement of the pattern of air movement into and out of the lungs during controlled ventilatory maneuvers.หายใจเข้าเต็มที่ หายใจออกแรงเต็มที่ ส่วนใหญ่ทำได้ในเด็ก > 6 ปีSilhouette of Hutchinson Performing Spirometry, From Chest, 2002
14Limitation They do not act alone. They act only to support or exclude a diagnosis.
15Mechanical Properties ComplianceDescribes the stiffness of the lungsvolume / pressureElastic recoilThe tendency of the lung to return to it’s resting stateA lung that is fully stretched has more elastic recoil and thus larger maximal flows
16Resistive Properties Determined by airway caliber Affected by Lung volumeBronchial smooth musclesAirway collapsibility
17Factors That Affect Lung Volumes AgeSexHeightWeightRaceDisease
18Special 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.
19Parameter from spirometer PEFRSpirogramFVCFEV1FEF25-75Flow-Volume Curve
20Technique Give instructions and demonstrate Acceptable criteria< 10 y: > 3 min> 10 y: > 6 minor no more volume > 1 minNot inhaleNo air leakNo pauseGive instructions and demonstratePatient performs the maneuverSit / Stand directPuts nose clip onInhales maximallyPuts mouthpiece on mouth and closes lips around mouthpieceExhales as hard and fast and long as possibleRepeat minimum of three times (check for reproducibility.)Use the best value for interpretation as %predicted of control (age, height, sex, race)2 maximum FVC different < 10%(adapted from ATS, 1994)
21FVC Forced vital capacity (FVC): Total volume of air that can be exhaled forcefully from TLCThe majority of FVC can be exhaled in <3 seconds in normal people, but often is much more prolonged in obstructive diseases
22FEV1 Forced expiratory volume in 1 second: (FEV1) Volume of air forcefully expired from full inflation (TLC) in the first secondNormal people can exhale more than 80% of their FVC in the first second (FEV1/FVC)
23FEF25-75 Forced expiratory flow 25-75% (FEF25-75) Mean forced expiratory flow during middle half of FVCMay reflect effort independent expiration and the status of the small airwaysHighly variableDepends heavily on FVC
25PEFR Peak flow meter device Technique Sit/Stand direct Inhales maximallyPuts mouthpiece on mouth and closes lips around mouthpieceBlow out as hard and fast as possibleRepeat minimum of three timesUse the best value for interpretation as %predicted / personal bestClinical application: monitor severity, daily variability, pre and post bronchodilatorGreen : > 80%Yellow : 50-79%Red : < 50%Normal < 20%Normal < 12%
26Categories of DiseaseObstructiveRestrictiveMixed
27FVC Interpretation of % predicted: 80 % Normal 70-79% Mild reduction 50%-69% Moderate reduction<50% Severe reduction
28FEV1 Interpretation of % predicted: >80% Normal 65-79% Mild obstruction50-64% Moderate obstruction<49% Severe obstruction
29Spirometry Interpretation: % predictedFVC> 80%FEV1FEF25-75%> 70%PEFRFEV1/FVC> 80% absolute value
30Spirometry in Obstructive Disease Slow rise in upstrokeMay not reach plateau
31Restrictive Disease Rapid upstroke as in normal spirometry Plateau volume is low
32Spirometry Interpretation: Obstructive vs. Restrictive Defect What parameter is the most sensitive in airway obstruction?ParameterObstructive DisordersRestrictive DisordersFVCFEV1FEF25-75%FEV1/FVCPEFRN or ↓ ↓↓ ↓↓ N to ↓↓ N or ↑↓ N to ↓
33Spirometry Interpretation: Obstructive DisordersCharacterized by a limitation of expiratory airflowExamples:AsthmaBronchiectasisCOPDCystic FibrosisRestrictive DisordersCharacterized by reduced lung volumes/decreased lung complianceExamples:Interstitial FibrosisKyphoscoliosisObesityLung ResectionNeuromuscular diseasesCystic FibrosisImprove FEV1 เมื่อ asthma ดีขึ้น
34Flow-Volume LoopPEFRDo 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.flowexpirationvolumeinspirationTLCRVRuppel GL. Manual of Pulmonary Function Testing, 8th ed., Mosby 2003
35Restrictive Lung Disease Characterized by diminished lung volumeDecreased TLC, FVCNormal or increased: FEV1/FVC ratio
36Obstructive Lung Disease Characterized by a limitation of expiratory airflowExamples: asthma, COPD
37Large Airway Obstruction Characterized by a truncated inspiratory or expiratory loop
38Incomplete exhalation Variable extrathoracic ob Flow-Volume LoopsL1R1L2R2L3R3Incomplete exhalationVariable extrathoracic obL4Variable intrathoracic obFixed central or up aw obInadq effortRestrictive lung disease(Rudolph and Rudolph, 2003)
39Spirometry: Pre and Post Bronchodilator Obtain spirogram and flow-volume loop.Pre and 15 minutes after administration of the bronchodilatorSalbutamol MDI 4 puffs via valve spacerSlow inhaleBreath hold 5-10 sec.5-10 sec pause between each puff.Reversibility: FEV1 / PEFR > 12%Improve flow-volume loop.
40PEFR Inhales maximally Exhales as hard and fast and short as possible Repeat minimum of three timesUse the best value for interpretation as %predicted of control / personal bestHighly effort dependentDiurnal variation (normal < 20%)Different value in each devices
41Exercise challenge test Perform spirometryExercise 6-8 min (tread mill) till HR /minRepeat spirometry at 5, 10, 15, 20, 30 minEIB: FEV %, or wheezing
42Respiratory muscle testing Measure maximum inspiratory P. (PImax, MIP) or negative inspiratory force (NIF)Maximum inhale via pressure manometerNormal < -60 cmH2OUseful for evaluation neuromuscular dis: myasthenia grevis, Guillian-Barre syndrome, diaphragmatic paralysis, pre-extubationOther parameter: FVC, PEFR