Pulmonary Function Tests

Size: px

Start display at page:

Download "Pulmonary Function Tests"

Wilfred Small
7 years ago
Views:

1 Pulmonary Function Tests Farah Madhani-Lovely Pulmonary/Critical Care Division December 13 th Indications and contraindications Spirometry Lung volumes Differentiating obstructive and restrictive lung disease Diffusion capacity 2 Indications To evaluate symptoms and signs of lung disease To assess the progression of lung disease To monitor the effectiveness of therapy To evaluate preoperative patients Screen people at risk of pulmonary disease To monitor for potentially toxic effects of certain drugs/chemicals 3 1

Contraindications Patient in respiratory isolation Inability to cooperate or sit up straight Acute illness Acute coronary syndrome Pneumonia Chest pain Current tracheostomy 4 Spirometry Measurement

2 Contraindications Patient in respiratory isolation Inability to cooperate or sit up straight Acute illness Acute coronary syndrome Pneumonia Chest pain Current tracheostomy 4 Spirometry Measurement of air movement in and out of the lung during different respiratory maneuvers. Values measured are: FVC: Forced Vital Capacity FEV1: The forced expiratory volume in one second MVV: Maximum Voluntary Ventilation 5 FEV 1 & FVC Forced expiratory volume in 1 second 4.0 L Forced vital capacity 5.0 L usually less than during a slower exhalation FEV 1 FVC FEV 1 /FVC = 80% 6 2

3 7 8 Spirometry Bronchodilator response is a change in FEV1 or FVC 200 ml AND 12% change in initial value 9 3

4 Maximal Voluntary Ventilation Fast and hard for seconds Normal estimated FEV1 x 40 Disproportional reduction in MVV Poor effort Variable exrathoracic obstruction Respiratory muscle weakness 10 LUNG VOLUMES Values obtained by simple spirometry For the others parameters additional measurements needed 11 FUNCTIONAL RESIDUAL CAPACITY Measured by body plethysmography helium dilution Body plethysmography mouthpiece obstructed rapid panting By applying Boyle s law (P V = constant) lung volume obtained 12 4

5 FUNCTIONAL RESIDUAL CAPACITY Helium dilution Spirometer of known volume and helium concentration connected to the patient Closed circuit Law of conservation of mass At beginning After several minutes [He] initial V s = [He] final (V s + V L ) Unknown lung volume can be calculated 13 LUNG VOLUMES Values obtained by simple spirometry For the others parameters additional measurements needed 14 INTERPRETATION of RESULTS In patients with obstructive diseases Higher resistance to airflow FEV1 (Forced expiratory volume) RV (residual volume) Patients with restrictive disease i.e. reduced lung compliance (e.g., diffuse interstitial fibrosis) stiffness of the lungs + recoil of the lungs to a smaller resting volume TLC (Total lung capacity) RV (residual volume) 15 5

6 FLOW-VOLUME CURVE in respiratory patients Restrictive disease expansion of the lung e.g., interstitial fibrosis FEV 1 FVC Obstructive disease resistance to airflow e.g., COPD, asthma 16 Obstructive Pulmonary Disease Chronic obstructive pulmonary disease (COPD) Asthma Bronchiectasis Cystic fibrosis Bronchiolitis obliterans 17 Obstructive Airway Disease Obstruction FEV 1 < 80% predicted FEV 1 /FVC < 70% 18 6

7 Extrathoracic airway obstruction 19 Extrathoracic airway obstruction 20 Intrathoracic airway obstruction 21 7

8 Intrathoracic airway obstruction 22 Fixed airway obstruction 23 Restrictive Pulmonary Disease Extraparenchymal Disease Chest wall deformity (kyphoscoliosis) Neurological disorder (myasthenia gravis) Muscular disease (myopathy) Abdominal pressure (ascites, obesity) Pleural Disease (effusion, fibrothorax) 24 8

9 Restrictive Pulmonary Disease Pulmonary parenchymal disease Pulmonary fibrosis Pneumoconiosis Granulomatous dz(sarcoidosis) Vasculitis 25 Restrictive Lung Disease VC, FRC, TLC < 80% FEV 1 /FVC = Normal Pseudorestriction NMDz Obesity 26 FLOW-VOLUME CURVE in respiratory patients Restrictive disease expansion of the lung e.g., interstitial fibrosis FEV 1 FVC Obstructive disease resistance to airflow e.g., COPD, asthma 27 9

Summary of Obstructive and Restrictive PFTS 28 Dependent on: Diffusion Capacity Alveolar capillary membrane Hemoglobin level Pulmonary capillary volume Single breath technique CO Need to hold your

10 Summary of Obstructive and Restrictive PFTS 28 Dependent on: Diffusion Capacity Alveolar capillary membrane Hemoglobin level Pulmonary capillary volume Single breath technique CO Need to hold your breath for 10 seconds 29 Diffusing capacity of the lung for CO (DL CO ) Detection and evaluation of restrictive disease Distinction of emphysema from other obstructive lung disorders Diagnosis of pulmonary hemorrhage 30 10

11 Restrictive Lung Disease VC, FRC, TLC < 80% FEV 1 /FVC > 80% Pulmonary-Parenchymal (Interstitial) Extra-pulmonary DL CO < 80% DL CO > 80% 31 Increased Diffusion Capacity Supine position Exercise Asthma Obesity Polycythemia Intra-alveolar hemorrhage L-R shunt 32 Decreased Diffusion Capacity Conditions that decrease surface area Emphysema, lung resection, bronchial obstruction, PE, anemia Conditions that increase capillary or alveolar wall thickness IPF, CHF, Asbestosis, Sarcoidosis, Collagen vascular disease, drug induced alveolitis, hypersensitivity pnemonitis Miscellaneous causes Heavy smokers, Pregnancy 33 11

12 34 12

RESPIRATORY VENTILATION Page 1

RESPIRATORY VENTILATION Page 1 Page 1 VENTILATION PARAMETERS A. Lung Volumes 1. Basic volumes: elements a. Tidal Volume (V T, TV): volume of gas exchanged each breath; can change as ventilation pattern changes b. Inspiratory Reserve