pulmonary function tests ppt

Pulmonary function tests (PFTs) are noninvasive tests that show how well the lungs are working. The tests measure lung volume, capacity, rates of flow, and gas exchange. This information can help your healthcare provider diagnose and decide the treatment of certain lung disorders.

1. Pulmonary function tests Dr. Chavan P. R. Pharm D

2. PFT Pulmonary function tests is a generic term used to indicate a battery of studies or maneuvers that may be performed using standardized equipment to measure lung function.  Evaluate one or more aspects of the respiratory system  Respiratory mechanics  Lung parenchymal function/ Gas exchange  Cardiopulmonary interaction

3. Aspects of pulmonary function: Perfusion- Blood flow. Diffusion- Movement of O2 & CO2. Ventilation- Air exchange btwn alveolar spaces & the atmosphere.

4. significance 1. Investigation of patients with symptoms/signs/ investigations that suggest pulmonary disease e.g. • (Cough/Wheeze/Breathlessness/Crackles) 2. Monitoring patients with known pulmonary disease for progression and response to treatment e.g. • Interstitial fibrosis • COPD • Asthma • Pulmonary vascular disease

5. 3. Investigation of patients with disease that may have a respiratory complications e.g. • Connective tissue disorders • Neuromuscular diseases 4. Preoperative evaluation prior to e.g. • Lung resection • Abdominal surgery • Cardiothoracic surgery

6. 5. Evaluation patients a risk of lung diseases e.g. • Exposure to pulmonary toxins such a radiation/ medication/environmental/occupational exposure 6. Surveillance following lung transplantation to assess for • Acute rejection • Infection • Obliterative bronchiolitis

7. Contraindications  Myocardial infarction within the last month  Unstable angina  Recent thoraco -abdominal surgery  Recent ophthalmic surgery  Thoracic or abdominal aneurysm  Current pneumothorax

8. Lung volume Four Lung volumes: Tidal volume (500-750ml) Inspiratory reserve volume(2500-3000ml) Expiratory reserve volume(1000-1500ml) Residual volume( 1300-1500ml)

9. Lung capacities Five capacities: Inspiratory capacity ( TV + IRV ) Expiratory capacity ( TV + ERV ) Vital capacity ( IRV + TV + ERV ) Functional residual capacity ( RV + ERV ) Total lung capacity(IRV+TV+ERV+RV)

10. tests Bed side pulmonary function tests Spirometry N2 Washout Technique Helium Dilution technique Body Plethysmography Cardiopulmonary interaction

11. Bed side pulmonary function tests 1. SABRASEZ BREATH HOLDING TEST >25 SEC.-NORMAL Cardiopulmonary Reserve 15-25 SEC- LIMITED CPR <15 SEC- VERYPOOR CPR (Contraindication for elective surgery ) 25-30 SEC - 3500 ml VC 20 -25 SEC - 3000 ml VC 15 -20 SEC - 2500 ml VC 10 -15 SEC - 2000 ml VC 5-10 SEC - 1500 ml VC

12. 2. SCHNEIDER’S MATCH BLOWING TEST MBC < 60 L/min FEV1 < 1.6L Able to blow out a match MBC > 60 L/min FEV1 > 1.6L Modified match test: DISTANCE MBC 9” >150 L/MIN. 6” >60 L/MIN. 3” > 40 L/MIN

13. 3. COUGH TEST Deep breath followed by cough Inadequate cough if: FVC<20 ml/kg FEV1 < 15 ml/kg PEFR < 200 l/min. VC ~ 3 times TV for effective cough.

14. 4.FORCED EXPIRATORY TIME Normal FET – 3-5 SECS. Obstructive Lung Disease. - > 6 SEC Restrictive Lung Disease.- < 3 SEC

15. 5. SINGLE BREATH COUNT After deep breath, hold it and start counting till the next breath.  N- 30-40 COUNT  Indicates vital capacity

16. 6. WRIGHT PEAK FLOW METER: Measures PEFR (Peak Expiratory Flow Rate) N – MALES- 450-700 L/MIN. FEMALES- 350-500 L/MIN.

17. 7. DE-BONO WHISTLE BLOWING TEST: MEASURES PEFR. Patient blows down a wide bore tube at the end of which is a whistle, on the side is a hole with adjustable knob. As subject blows → whistle blows, leak hole is gradually increased till the intensity of whistle disappears. At the last position at which the whistle can be blown , the PEFR can be read off the scale.

18. 8. WRIGHT RESPIROMETER : measures TV,MV Instrument- compact, light and portable. Can be connected to endotracheal tube or face mask MV- instrument record for 1 min. And read directly TV-calculated and dividing MV by counting Respiratory Rate. Disadvantage : It under- reads at low flow rates and over- reads at high flow rates.

19. spirometry

20. Prerequesite  Do not smoke for at least 1 hour before the test.  Do not drink alcohol for at least 4 hours before the test.  Do not exercise heavily for at least 30 minutes before the test.  Do not wear tight clothing that makes it difficult for you to take a deep breath.  Do not eat a large meal within 2 hours before the test.

21. Spirometry

22. DISADVANTAGE • Only for single use due to CO2 accumulation & O2 cannot be supplied. • Residual Volume, Functional Residual Capacity and Total Lung Capacity cannot be measured.

23. N2 Washout Technique The patient breathes 100% oxygen, and all the nitrogen in the lungs is washed out. The exhaled volume and the nitrogen concentration in that volume are measured. The difference in nitrogen volume at the initial concentration and at the final exhaled concentration allows a calculation of intrathoracic volume, usually FRC.

24. Helium Dilution technique Pt breathes in and out from a reservoir with known volume of gas containing trace of helium. Helium gets diluted by gas previously present in lungs. eg : if 50 ml Helium introduced and the helium concentration is 1% , then volume of the lung is 5L.

25. Body Plethysmography Plethysmography (derived from greek word meaning enlargement). Based on principle of BOYLE’S LAW(P*V=k) A patient is placed in a sitting position in a closed body box with a known volume The patient pants with an open glottis against a closed shutter to produce changes in the box pressure proportionate to the volume of air in the chest. As measurements done at end of expiration, it yields FRC

26. Cardiopulmonary interaction Stair climbing test Shuttle walk test 6min walk test Cardiopulmonary exercise test

27. Stair climbing test

28. Shuttle walk test Walk test is based on 20m shuttle walk test Measures maximum distance walked by the patient at a pace set by audio signals Requires patients to walk at increasing speads up and down a 10m course Speed walking is increased every minute by 0.17m/s

29. 6min walk test The tester will measure your blood pressure, pulse and oxygen level usually with a pulse oximeter before you start to walk . You should be given the following instructions: The object of the test is to walk as far as possible for six minutes. You will walk at your normal pace to a chair or cone, and turn around. And you continue to walk back and forth for six minutes . Let the staff know if you are having chest pain or breathing difficulty . It is acceptable to slow down, rest or stop. After every minute interval, you will be given an update.

30. Cardiopulmonary exercise test

31. Thank you