Pulmonary Function Test interpetation ppt

Pulmonary function test

1. Pulmonary Function Test and Its Interpretation Chairperson: Asst. Prof. Dr. Snehangshu Shekhar Samanta Presenter : Dr. Arijit Biswas

2. Its a generic term used to indicate a battery of test or manouvers performed using standardised equipment to evaluate function of lung. What is Pulmonary Function Test?

3. Tests for ventilatory functions: Evaluate lung volumes and capacities :  - Spirometry  - Body Plethysmography  - Gas dilution method ( FRC & RV detection) Evaluate hypersensitivity of airway - Bronco provocation test Components

4. 2.Tests for gas exchange: DLCO , ABG, Oxymetry and Capnography . 3. Other Tests: Tests for lung compliance. Test for resistance and impedence : Impulse oscillometry . Assessment of regional lung functions. Assessment of respiratory muscle strength. Breath condensate. Components

5. Gives the evidence of deranged lung function Helps to rule out/ identify resp cause of SOB Quantifying lung function in pt undergoing lung resection Type of resp failure Detects airway hyper responsiveness Evaluation of disability Course of disease over time Significance of PFT

6. SPIROMETRY  

7. TYPES OF SPIROMETER VOLUME DISPLACEMENT SPIROMETER: FLOW SENSING SPIROMETER:

8. Volumes and capacities 500ml 4.5l 1.2+1 L 1.2L 1L 4.5+1.2 L 3L TV= AMOUNT OF GAS GOING IN AND OUT WITH EACH RESPIRATION

9. Volumes and capacities 500ml 4.5l 1.2+1 L 1.2L 1L 4.5+1.2 L 3L IRV= EXCESS AIR THAT CAN BE BREATHED IN WITH EXTRA EFFORT AFTER TIDAL INSPIRATION

10. Volumes and capacities 500ml 4.5l 1.2+1 L 1.2L 1L 4.5+1.2 L 3L ERV= EXTRA AMOUNT OF GAS THAT CAN BE BREATHED OUT WITH EXTRA EFFORT AFTER TIDAL EXPIRATION

11. Volumes and capacities 500ml 4.5l 1.2+1 L 1.2L 1L 4.5+1.2 L 3L RV= AIR LEFT BEHIND AFTER MAX EXPIRATION

12. Volumes and capacities 500ml 4.5l 1.2+1 L 1.2L 1L 4.5+1.2 L 3L FVC= AMOUNT OF AIR THAT CAN BE BREATHED OUT WITH MAX EFFORT AFTER FORCEFUL INSPIRATION

13. Volumes and capacities 500ml 4.5l 1.2+1 L 1.2L 1L 4.5+1.2 L 3L FRC= AMOUNT OF AIR LEFT IN LUNG AFTER NORMAL TIDAL EXPIRATION

14. SPIROMETRY It can measure: Tidal vol (500ML) IRV (3L) ERV (1L) VC (4.5L) What it can not measure: RV FRC = ERV+ RV TLC = FVC+ RV

15. Indications Diagnostic: To evaluate symptoms, signs, and abnormal lab test s Symptoms : dyspnea wheezing, orthopnea , cough, phlegm production, chest pain Signs: diminished breath sound, over inflation, expiratory slowing, cyanosis, chest deformity, unexplained crackles Abnormal lab test : hypoxemia, hypercapnia , abnormal chest radiograph B. To measure the effect of disease on pulmonary function

16. C. To screen individuals at risk of having pulmonary disease Smokers Occupational exposure D. To assess preop risk prognosis( lung transplant) health ststus before begining of a strenous physical activity program Indications

17. 2 . Monitoring To assess therapeutic intervention Bronchodilator therapy Steroid therapy (Asthma, ILD) Antibiotics in cystic fibrosis To describe the course of disease that affect lung function Pulmonary disease (obstructive airway disiese,ILD ) Cardiac disease (CHF) NM disorders (GB syndrome) Indication

18. To monitor people exposed to injurious agent To monitor adverse reaction to drug with known pulmonary toxicity 3.To identify Flow Volume Loop patterns 4. Disability/Impairment evaluation To assess patients as part of rehabilitation program To assess risk as a part of an insurance evaluation 5. Public Health : For clinical research Indications

19. Due to increased myocardial demand AMI within1WK Hypo / severe hypertension Ventr arrhythmia / non compensated HF PAH / Acute corpulmonale Relative contraindications Due to increased intracranial/intraocular/ intrathoracic pressure Cerebral aneurysm Brain surgery 4wk Eye surgery 1 wk Pneumothorax Thoracic/ abd sx 4wk Late term pregnancy Infection controle issue Active / transmissable resp inf (TB/ covid ) Hemoptysis Oral lesion/ bleed Should be discontinued if pt feels pain during procedure

20. In pulm funtion lab, where operator are experienced enough, Emergency care can be given if needed Callibration of the device Quiet and calm env . Temp and barometric pressure is a important variable in PFT Pre-requisite

21. Smoking within 1 hr Consuming intoxicants before 8hr of test Vigorous exercise within 1 hr Tight clothes that interrupt chest and abd wall expansion freely Activites that should be avoided before PFT?

22. Seated erect Shoulder slightly back, Chin slightly up Chair without wheel with height adjustment Feet should be flat on the floor Nose clip or manual occlusion of nose should be used Test in standing position are more or less similar to sitting Position

23. Spirometry can be a major source of infection as well as place of infection transmission Directly by : Mouthpiece, noseclip , chair arms Indirectly by : Aerosol droplet generation Avoide this risks by : Handwashing /sanitisation Use of disposable equipment where possible Hygiene and infection controle

24. Methodology/ Procedure

25. FEV1 and FVC manouver Expiration only manouver Bronchodialator responsive testing manouver (Reversibility test) SVC (slow vital capacity) manouver Manouvers

26. Equipment must be Calibrated Loosen tight fitting clothes Dentur e if they are loose better tobe removed Age, Weight, Height is recorded Explain the pt about the procedure Counsel that the procedure may not be comfortable Checklist

27. Maximum inspiration Start at flow zero Inspire as deeply as possible No pause Wait till the inspiration is complete ( eye brow becomes widened, head starts quivering) Blast of expiration D on’t just blow, blow as much and as forcefully possible Continued expiration At least 6 sec is acceptable 3 sec for <10 yrs Wait for the plateau phase in display Ask for the next step Maximum inspiration after forced expiration To return to TLC and complete the flow volume curve This will cross check whether the pt began exp from full inspiration or not FEV1/FVC MANEUVER

28. Expiration only manouver (Done for children only) Inspire maximum lung vol within 2 s Insert mouth piece Innitiate max expiration Remove mouth piece at end of forced expiration

29. Bronchodialator responsive test Degree of improvement of air flow in response to bronco dilator Can differentiate Asthma from other COPD But neither asthma nor COPD is diagnosed on spirometry bronchodilator Dose FEV1 before and after Salbutamol 200-400mcg via large spacer 15 min Terbutaline 500 mcg via turbohaler 15 min Ipratropium 160 mcg via spacer 45 min

30. The test can be concluded when both ACCEPTABILITY and REPEATABILITY criteria are met To ensure the REPRODUCIBILITY of the test Requires 5 to maximum 8 attempt

31. Free from artefact ( Cough / Early glottis closure) Good start Free from leaks Extrapolation back from the PEFR gives a theoretical start time (should be within 5% of FVC or within 150 ml) Acceptable exhalation Adults :at least 6 sec of exhalation and plateue Children <10yrs : at least 3 sec of exhalation Acceptability criteria

32. Three acceptable maneuvers (meeting above criteria) Two largest FVC measurements within 150 ml of each others Two largest FEV1 measurements within 150ml of each others Repeatability criteria

33. FVC FEV1 FEF 25-75 Change in FVC and FEV1 after broncho dialator use Flow volume curve Flow time curve Data extracted

34. Flow volume Loop FEV! Effort dependent part Effort independent part PEFR

35. Flow time curve

36. Total volume of air that can be exhaled forcefully from TLC The majority of FVC can be exhaled in<3 seconds in normal Often prolonged in Obstructive lung disease Measured in liters Forced Vital Capacity(FVC)

37. 80-120% = Normal 70-79% = Mild reduction 50-69% = Moderate reduction <50% = Severe reduction FVC – Interpretetion of % predicted

38. Volume of air forcefully expired from full inspiration (TLC) in first second Normally 75-80% of FVC is exhaled in first second Thus FEV1/FVC can be utilised to characterise lung disease Forced expiratory volume in first sec (FEV1)

39. Mean forced expiratory flow during middle half of FVC May reflect effort independent expiration And the status of the small air way Forced expiratory flow 25-75% (FEF25-75)

40. Forced expiratory flow 25-75% (FEF25-75)

41. >60% normal 40-60% mild obstruction 20-40% moderate obstruction <20% Severe obstruction FEF25-75 Interpretetion of % predicted

42. INTERPRETETION FVC alone does not make any sense unless and until we compare it with the time dimension i.e. FEV1 Main determinant of PFT is the FEV1/FVC FEV1/FVC (>80%) LOW Normal/high Always obstructive Restrictive

43. Obstructive COPD (Emphysema/ Bronchiectasis /SAD) ASTHMA CF BRONCHIOLITIS BRONCHIECTASIS For expiration driving force >Air pressure Driving force = IPP + Elastic recoil pressure Elastic recoil pressure is low in obstructive ds That is why exp function (FVC) starts falling day by day Hyperinflation Air trapping FEV1 low Low FVC normal Low RV High High TLC (FVC+RV) High Remain unchanged

44. Obstructive

45. Q . Can obstr lung dis have normal FEV1/FVC ? Yes, in Small air way disease. Here we diagnose SAD by FEF 25-75 / MMEFR/MEAN FORCED EXPIRATORY FLOW RATE It is the average flow rate of lung in middle 50% of the FVC manouver It is the slope of the line

46. Reversibility test by SABA If FEV1 > 12% and FVC > 200ml Bronchial asthma vs other copd It indicates Bronchial Asthma

47. RVERSIBILITY TEST

48. Here lung’s inspiratory function is affected So IRV is decreased FVC= IRV + TV +ERV = FVC FEV1 remains normal more or less FEV1/FVC remains normal/high Restrictive lung disease

49. Restrictive lung disease

50. Flow volume Loop

51. Restrictive DLCO normal DLCO low KCO normal

52. Intra parenchymal NM disorder Chest wall deformity DLCO LOW NORMAL TLC LOW LOW NORMAL RV LOW NORMAL RV/TLC HIGH NORMAL KCO (DLCO/VOL) NORMAL HIGH Differenciation of restrictive lung disease

53. It uses a small amount of CO to measure gas exchange across the alveolar membrane during a 10 sec breath hold. CO in exhaled air is analysed to determine the quantity of CO crossing the membrane DLCO (Diffusion capacity of lung for CO)

54. FACTORS INCREASD DLCO DECREASED DLCO Thickness of alveolar membrane ILD smoking Altered volume/surface area ratio Emphysema Hb available Polycythemia Anaemia Pregnancy Blood coming to capilleris Pulmonary Hge Asthma Left to right shunt Exercise Pulmonary vascular disease Factors affecting DLCO

55. Diffusion limited gas Affinity of Hb for CO is >200 times Partial pressure of CO in pulmonary capillaries rises very slowly Why CO? KCO (Diffusion coefficient)= DLCO/ Lung Volume Normal in ILD Raised in Extra parencymal disease

56. Intra parenchymal NM disorder Chest wall deformity DLCO LOW NORMAL TLC LOW LOW NORMAL RV LOW NORMAL RV/TLC HIGH NORMAL KCO (DLCO/VOL) NORMAL HIGH Differenciation of restrictive lung disease

57. Different flow vol loops NORMAL Scooped pattern Fixed airway obstruction Extra thoracic variable obstruction Intra thoracic variable obstr

58. LEVEL OF OBSTRUCTION

59. Narrowing is maximal in Expiration As lesion is intra thoracic Intra thoracic pressure is maximum in expiration and lower than air Thus expiratory limb is flattened Variable intra thoracic obstruction e.g. Tracheomalacia

60. Obstruction worsens in inspiration As negative pressure narrows trachea Thus Inspiratory limb flattens E.g extrinsic compression from Goiter , LN Variable extra thoracic obstruction

61. Maximum airflow is limited to a similar extent in both inspiration as well as expiration Both limbs are affected E.g. Tracheal stenosis , FB Fixed upper airway obstruction

62. Most common cause is poor patient technique Sub optimal inspiration Sub maximal expiratory effort Delay in forced expiration Shortened expiratory time Air leak around the mouth piece Poor posture = leaning forward Subjects must be observed and encouraged through the procedure Common problems and artefacts

63. Cough during spirometry

64. Acceptable and unacceptable flow volume loop Premature ending

65. Highly dependent on patient compliance and effort Thus FEV1 and FVC may be underestimated Not useful for <4years/ unconcious /sedated Can not measure RV,FRC,TLC Limitation

66. Take home meesage

67. Thank you