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Interpretation of Pulmonary Function Test
- 1. A Stepwise Approachto the Interpretation of Pulmonary Function Tests Dr Suman Roy PGT
- 6. Why PFTs? • Dxof Symtomatic Ds • Screening of Early Asymtomatic Ds • Prognostication of Known Ds • Monitoring Response to Known Ds
- 7. Purpose of PFTs? As a dx tool it helps to classify LD into 1 of 3 broad categories Obstructive Lung Disease Restrictive Lung Disease PulmonaryVascular Disease COPD (Chr. Bronchitis< ->Emphysema) Asthma Bronchitis Cystic Fibrosis ILD ( Pul Fibrosis, Sarcoidosis) Chest Wall Pathology ( Kyphosis, Scoliosis) Obesity Neuromascular Disease ( ALS, Mascular Dystrophy) Pr Pul HTN Chr Thromboembolic Ds These categories are not mutually exclusive : COPD can be Obstructive + Vascular Sarcoidosis can be Restrictive + Obstructive + Vascular
- 8. Function of PulmonarySystem Tested by PFTs • Airways Large & Small Airways • Parenchyma Alveoli Interstitium • Pulmonary Vasculature • Bellows/Pump Mechanism Diaphragm Chest Wall • Neural Control of Ventilation
- 14. How Spirometry isperformed?
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- 20. Values Measured bySpirometry Major Minor FEV1 FVC FEV1/FVC Flow Volume Loop Peek Expiratory Flow Rate (PEFR) PEF (25-75) Maximum Voluntary Ventilation Response to Bronchdilators
- 21. Interpretation of FEV1,FVC & FEV1/FVC Ratio FEV1 FVC FEV1 / FVC Ratio ( Tiffeneau Index) Obstructive Lung Disease Normal Very mild obstruction or Decreased Mod / Severe Obstruction Normal Mild / Moderate obstruction Decreased Severe obstruction Decreased < 70% Restrictive Lung Disease Normal or Decreased Decreased Normal or Increased 70 % or More
- 22. Interpretation of Spirometry AssessLow Assess Normal/High Assess FVC FEV1/FVC FVC LOW Normal Low Normal Obstruction Obstruction Possible Normal Lung Or Mixed Restriction Mechanics Where is Pulmonary Vascular Disease ?
- 40. Staging of COPDBased on FEV1 The Global initiative for Chronic Obstructive Lung Disease (GOLD) classifies COPD severity based on post-bronchodilator FEV1 FEV1 compared to predicted for Age/gender/height GOLD Stage I FEV1 _> 80% GOLD Stage I I 50% _< FEV1 _< 80% GOLD Stage I I I 30% _< FEV1 _> 50% GOLD Stage I V FEV1 _< 30% FEV1/FVC < 0.7 There is weak co-relation between FEV1 & Quality of Life
- 41. GOLD Criteria forSeverity of Airflow Obstruction in COPD GOLD Stage Severity Spirometry • I Mild FEV1/FVC <0.7 FEV1 ≥80% predicted • II Moderate FEV1/FVC <0.7 FEV1 ≥50% but <80% predicted • III Severe FEV1/FVC <0.7 FEV1 ≥30% but <50% predicted • IV Very severe FEV1/FVC <0.7 FEV1 <30% predicted