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Lung Function Tests

Lung Function Tests. Sema Umut. Lung Factors Affecting Function. Mechanical properties Resistive elements. Mechanical Properties. Compliance Describes the stiffness of the lungs Change in volume over the change in pressure Elastic recoil

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Lung Function Tests

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  1. LungFunctionTests Sema Umut

  2. Lung Factors AffectingFunction • Mechanical properties • Resistive elements

  3. Mechanical Properties Compliance • Describes the stiffness of the lungs • Change in volume over the change in pressure Elastic recoil • The tendency of the lung to return to it’s resting state

  4. Resistive Properties • Determined by airway caliber • Affected by • Lung volume • Bronchial smooth muscles • Airway collapsibility

  5. A TEST SHOULD BE • Acceptabile,easy • Noninvasive • Cost effective • Informative • Reproducible

  6. Spirometry Acceptabile,easy Noninvasive Costeffective Inexpensive Informative Reproducible

  7. Spirometry • It is the most commonly used lung function screening study • It should be the clinician's first option

  8. When can spirometry help us? • - Diagnosing disease • - Monitoring disease • - Prognosis • Directing therapy

  9. Indications for Spirometry Diagnostic • To evaluate symptoms, signs, or abnormal laboratory tests • Dyspnea • Wheezing • Cough • Abnormal breath sounds • Overinflation • Expiratory slowing • Cyanosis

  10. Abnormallaboratorytests • Hypoxemia • Hypercapnia • Polycythemia • Abnormal chest radiographs

  11. To screen individuals at risk of having pulmonary diseases • Smokers • Individuals in occupations with exposures to injurious substances

  12. Indications for Spirometry • To assess preoperative risk • To assess health status before physical activity programs • To evaluate therapy

  13. Disability/ImpairmentEvaluations • To assess individuals for legal reasons

  14. Prognosis Survival predictor of general population Copenhagen City Heart Study 13,900 subjects for 25 yrs Lange P. J Clin Epidemiol 1990; 43: 867-873. Cox proportional hazards FEV1/ht2 best index Framingham study

  15. Spirometry Requirements 1. Good equipment 2. Good technicians (efor dependent) 3. Good clinicians - correct indication - correct use / presentation of the data - correct decision making

  16. Pulmonary Function Testing relates • Age : Smaller lung volumes as we age • Gender : The lung volumes of males are larger than females • Height • Race

  17. Perform manoeuvre • Attach nose clip, place mouthpiece in mouth • Inhale completely and rapidly • Exhale maximally until no more air can be expelled • Repeat for a minimum of 3 manoeuvres

  18. ForcedVitalCapacity FVC • Total volume of airexpiredforcefullyafter a fullinspiration • Patientswithrestrictivelungdiseasehave a decreasedvitalcapacity

  19. Slow Vital Capacity (SVC) • This is the total volume of air expired slowly after a full inspiration • If the SVC is greater than FVC,it indicates the presence of obstructive disease

  20. Forced Expiratory Volume in 1 Second FEV1 Volume of air expired in the first second during maximal expiratory effort

  21. FEV1/FVC • Percentage of the forced vital capacity which is expired in the first second of maximal expiration to forced vital capacity • In health the FEV1/FVC is usually around 80% • Decrease in FEV1/FVC means obstruction

  22. Tidal volume TV The volume of air moved during normal quiet breathing (about 0.5 L)

  23. RESIDUEL VOLUME (RV) The volume of air remaining in the lungs after a forceful expiration (about 1.0 L).

  24. FUNCTIONAL RESIDUEL CAPACITY(FRC) The amount of air remaining in the lungs after a normal quiet expiration

  25. TOTAL LUNG CAPACITY (TLC) It is the volume of air in the lungs when the person has taken a full inspiration TLC = RV + VC

  26. TLC,RV,FRC Can not be measured by spirometry • Helium dilution • Nitrogenmetry • Body plethysmography

  27. INTERPRETATION OF SPIROMETRY • Compare the measured values of the patient with normal values derived from population studies • The percent predicted normalis used to define normal and abnormal and to grade the severity of the abnormality

  28. Categories of Disease • Obstructive • Restrictive • Mixed

  29. Spirogrammeasurestwocomponents - airflowandvolume Ifflow is reduced, thedefect is obstructive Ifvolume is reducedthedefect is restrictive

  30. Interpretation FVC and FEV1 are normal – NORMAL FVC is low but FEV1/FVC is >80 RESTRICTIVE FEV1/FVC < 70% OBSTRUCTIVE

  31. Spirometry • Obstruction (FEVı /FVC) < %70

  32. Obstructive Lung Diseases • Asthma • Chronicobstructivepulmonarydisease

  33. COPD -COPDis characterized by airflow limitation that is not fully reversible -The airflow limitation is usually progressive and associated with an abnormal inflammatory response of the lung to noxious particles or gases

  34. Diagnosis of COPD EXPOSURE TO RISK FACTORS SYMPTOMS cough tobacco sputum occupation shortness of breath indoor/outdoor pollution è è è SPIROMETRY

  35. Asthma • Asthma is a chronic inflammatory disease of the airways • Inflammation causes the airways to narrow periodically • Thisproduces wheezing and breathlessness • Obstruction to air flow is reversible

  36. Bronchodilator Test • Evaluates how responsive the patient is to a bronchodilator medication • Spirometry is repeated about 15 minutes after giving a bronchodilator (400 mg salbutamol)

  37. WHY TEST FOR REVERSIBILITY? • To determine best function • To follow rate of change in PFTs over time • To exclude asthma • To determine response to therapy

  38. REVERSIBILITY Increase of 200 ml or 12-15% of the baseline FEV1 shows REVERSIBLE OBSTRUCTION 40 Both drugs combined 30 20 10 0 0 2 4 6 8

  39. Restriction • Restriction means a decrease in lung volumes

  40. Extrinsic Restrictive Lung Disorders . Neuromuscular Disorders . Scoliosis, Kyphosis . Rib fractures . Pleural Effusion . Pregnancy . Gross Obesity . Tumors . Ascites

  41. Intrinsic Restrictive Lung Disorders • Pnuemonectomy • Pneumonia • Lung tumors • Interstitial lung diseases • Sarcoidosis • Lung oedema

  42. Flow – Volume Loop is a measure of how much air can be inspired and expired from the lungs It is a flow rate measurement

  43. Restrictive Lung Disease • Characterized by diminished lung volume • Decreased TLC, FVC • Normal FEV1/FVC ratio

  44. Large Airway Obstruction can be detected by Flow – Volume Loop • Characterized by a truncated inspiratory or expiratory loop

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