Clinical Application of Pulmonary Function Tests

1. Clinical Application of Pulmonary Function Tests Sevda Özdoğan MD, Prof. Chest Diseases

2. Pulmonary Function Tests • Spirometry (SVC) • Flow Volume Curve • MVV • Diffusion test • Reversibility and Provocation tests • Exercise tests • 6 minutes walking test • Cardiopulmonary exercise tests • A physiological test that measures how an individual inhales or exales volumes of air as a function of time • a) Volume • b) Flow

4. İndications for PFT • Diagnostic • To evaluate dispnea!! • To assess the etiology of dyspnea (cardiac/pulmonary) • To measure the effect of the disease on pulmonary function • To assess any airway obstruction, the severity of the obstruction and response to bronchodilators • To assess prognosis

5. To assess preoperative risk • To assess etiology of chronic cough • To assess respiratory muscle strenght • To measure gas diffusion • To monitor for adverse reactions to drugs with known pulmonary toxicity • Disability/impairment evaluations • Epidemiological or clinical survey

7. Definitions • Static Lung Volumes: • Tidal Volume (TV): The volume of gas inhaled and exhaled during a respiratory cycle (resting) • Expiratory Reserve Volume (ERV): Maximum volume of gas that can be exhaled from the end expiratory level during tidal breathing • Inspiratory Reserve Volume (IRV): Maximum volume of gas that can be inhaled from the end inspiratory level during tidal breathing • Total Lung Capacity (TLC): The volume of gas in lungs after maximal inspiration (Sum of all compartments)

8. Vital capacity (VC): Maximal volume of air exhaled from a position of full inspiration • Residuel Volume (RV): The volume of gas remains in the lung after maximal exhalation • Functional Residuel Capacity (FRC): The volume of gas present in the lung at end expiration during tidal breathing

9. Static lung volumes can be measured by: • Spirometry (SVC maneuver) • Body pletismography PxV=k • Washout Techniques • Nitrogen Washout: Based on washing out the N2 from the lungs when the patient breathes 100% O2 • Multipl breath Body pletismography

10. Helium dilution: • Based on the equlib- • ration of gas in the • lung with a known • Volume of gas • containing helium

11. Slow vital capacity • After 2-3 normal breathing (TV) • Make a slow maksimum inspiration (TLC) • Then make a slow maksimum expiration (VC)

12. Static Lung volumes are decreased in • Restrictive lung diseases • Atelectasis • Lobectomy, pneumonectomy • Chest wall deformities • Diaphragmatic paralysis • Neurologic pathologies • Hiatus hernia (Normal values are calculated according to the patients age, height, weight)

13. Dynamic Lung Volumes (Flow volume Curve) • Forced Vital Capacity (FVC): is the maximal volume of air exhaled with maximaly forced effort from a maximal inspiration. • Forced Expiratory Volume 1 (FEV1): the maximal volume of air exhaled in the first second of forced expiration from a position of full inspiration

16. Peak expiratory flow (PEF): The maximum flow rate reached during a forced expiration • FEF 25-75%: Average expiratory flow over the middle half of FVC (MMEF) Decreases in small airway obstructions

17. Maximum Voluntary Ventilation (MVV): A dynamic test in which the patient breaths rapidly and deeply for 10-15 seconds. The total volume (inhaled and exhaled) is calculated and expressed as L/min) Decreases in obstructive and restrictive diseases as well as neuromuscular diseases

18. Dynamic lung volumes and flow rates are decreased in: • Obstructive lung diseases (COPD, Asthma)

19. İnpiratory parameters are also important especially in upper airway pathologies • MIF; IC; FIV1

23. Yes No Reversibility? Yes No Yes No Furtherexamination Asthma No Yes COPD

24. Staging in pulmonary function abnormalities

25. Reversibility • Assessment of postbronchodilator response in obstructive pathologies • Spirometry is repeated 15-20 minutes after the administration of an inhaled short acting bronchodilator. An 12-15% increase in FEV1 or an absolute value of 200 ml increase represents a significant positive reversibility test.

27. Bronchoprovocation test (Challenge) • Performed in patients who have suspected reactive airway disease with normal spirometry. • Can be performed by • Methacoline • Histamine • Cold air inhalation? • Exercise Most frequently

28. Methacoline responsiveness: • Starting with a single inhalation at a very low concentration, patients are tested each time after progresively increasing inhaled doses until • Either a predetermined maximum dose (16 mg/ml) has been achieved • Or FEV1 has been observed to fall by 20%

30. CO Diffusion test • The capacity of the lung to exchange gas across the alveolocapillary interface is determined by DLCO • This process is a passive diffusion and is a function of • Pressure difference • Surface area • Resistive properties of the membrane • CO gas is used as the test gas because of its high affinity to hb

31. Single breath method

33. Staging in pulmonary function abnormalities

34. Cardiopulmonary Exercise Testing • To assess a patients exercise capacity objectively • To observe the response of the components of oxygen delivery system to this stress • To determine the factors that limit exercise capacity or cause exertional dyspnea

35. Performed on • Treadmill with increasing speeds and slope • Bicycle pedaled at a constant rate with a variable resistance • Load is increased in a continious ramp or at intervals • ECG, Pulse oxymeter, respiratory rate, Vt, minute ventilation and blood gases are monitored

36. Parameters measured • Oxygen consumption (VO2max) • Heart rate • Oxygen pulse • Blood pressure • Ventilation (VEmax) • Anaerobic treshold • Arterial blood gases