Pulmonary function testing
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The document outlines pulmonary function testing (PFT), detailing its definition, purpose, indications, contraindications, and classifications of lung conditions. It explains how PFT evaluates lung function through various parameters, including lung volumes and capacities, and differentiates between obstructive and restrictive lung diseases. Additionally, it describes the interpretation of flow-volume curves and key respiratory metrics essential for clinical assessment.
Pulmonary function testing
- 1. Dr.Nidhi Ahya Assistant Professor Cardio-Vascular & Respiratory PTDVVPF College of Physiotherapy, Ahmednagar 414111
- 2. Definition Purpose Indications & contra-indication lung volumes & capacities Flow – volume curve Classification : obstructive & restrictive Clinical interpretation.
- 3. Pulmonary function testing is the process of having the patient perform specific inspiratory and expiratory maneuvers while breathing in and out of tubing attached to the equipment that measure a variety of variables
- 4. To determine the functional status of the lungs How much gas can be moved in and out of the lungs How fast gas can be moved The stiffness of the lung and chest wall The diffusion characteristics of the alveolar-capillary membrane How well lung responds to the therapy
- 6. • To evaluate symptoms, signs or abnormal laboratory tests • To measure the effect of disease on pulmonary function • To differentiate between obstructive and restrictive disease • To screen individuals at risk of having pulmonary disease • To assess pre-operative risk • To assess prognosis, response to therapy
- 7. • Hemoptysis of unknown origin • Pneumothorax • Unstable cardiovascular status or recent MI or pulmonary embolus • Thoracic, abdominal or cerebral aneurysms • Presence of an acute disease process that might interfere with test performance • Recent surgery of thorax and abdomen
- 8. Nosocomial infection contracted from improperly cleaned tubing, mouthpiece
- 9. Height and weight: Taller person, larger lung size, and larger predicted lung volume Muscular person-increase in lung size Obese person-reduction in lung size Gender: Males>females Age: Vital capacity increases in person until mid 20s Average predicted VC for 20yrs is slightly over 5lt By age 70, approx 4lt Race Environmental factors Personal Factors
- 11. Volume of air exhaled and inhaled during quiet breathing 350-600ml Decrease Vt can occur both in restrictive an obstructive defects
- 12. The inspiratory reserve volume is the extra volume of air that can be inspired over and above the normal tidal volume when the person inspires forcefully. It is usually equal to about 3000 ml
- 13. The expiratory reserve volume is the maximum extra volume of air that can be expired by forceful expiration after the end of a normal tidal expiration It normally amounts to about 1100 ml
- 14. The residual volume is the volume of air remaining in the lungs after the most forceful expiration This volume averages about 1200 Ml Is reduced in restrictive defects Increased in obstructive defects Expressed as ratio to TLC and VC
- 17. The inspiratory capacity equals the tidal volume plus the inspiratory reserve volume. It’s the amount of air a person can breathe in, beginning at the normal expiratory level and distending the lungs to the maximum amount. about 3500 milliliters
- 18. The vital capacity equals the inspiratory reserve volume plus the tidal volume plus the expiratory reserve volume. This is the maximum amount of air a person can expel from the lungs after first filling the lungs to their maximum extent and then expiring to the maximum extent About 4600 ml If the person forcefully exhales the volume, it is called Forced vital capacity(FVC)
- 19. Three phases of FVC maneuver: Maximal inspiratory effort Initial expiratory blast Forceful emptying of the lungs Both restrictive and obstructive defects can cause decrease in VC Important preoperative assessment factor useful in evaluating the patient’s need for mechanical ventilation
- 20. FRC = ERV+RV Resting volume of the lungs after exhalation of Vt breath This is the amount of air that remains in the lungs at the end of normal expiration About 2300 ml Represents balance between the expanding chest wall forces and the contractile rebound forces of lung tissue
- 21. Sum of VC and RV Is increased with most obstructive lung defects and decreased with restrictive lung defects To measure TLC, RV must be determined
- 22. The lung volumes that can be directly measured using a spirometer include- Tidal Volume, Inspiratory Reserve Volume, Expiratory Reserve Volume and thus Vital Capacity Total Lung Capacity can be measured if RV and FRC are known. RV and FRC is obtained in one of indirect methods: Body plethysmograph (body box) Open-circuit nitrogen washout Closed-circuit helium dilution
- 23. Generated by integrating flow with volume on graph Volume is plotted on the horizontal axis Flow on the vertical axis Expiratory loop is shown above the line
- 24. Generated by integrating volume with time on graph Volume is plotted on the vertical axis Time on the horizontal axis Volume – Liters Time- secs
- 25. The expiratory side of the FVC curve provides data regarding the contractile state of the airways This part of the curve evaluates the amount of the obstruction present in the patient’s airways Routinely identified flows are: FEV1 --FEV25%-75% FEV3 --PEF
- 26. Measures the maximal volume of air exhaled during the first second of expiration Reflects the flow characteristics in the larger airways Best indicator of obstructive diseases Expressed as percentage of the observed FVC (FEV1/FVC) Normal: 75% of VC in 1 second Decreased: acute and chronic obstructive pulmonary disease Normal in restrictive disorders
- 27. Look at the 3-second point of the expired curve Indication of the flow in smaller airways Decrease normally with age Normal: approx 95%
- 28. FEV25%-75% Expressed in liters/second Indicator of flow First 25% is disregarded because of the lung’s initial inertia Last 25% is disregarded because of effort dependency Middle 50% reflects the degree of airway patency Early indicator of obstructive disease Can also be reduced in restrictive dysfunction
- 29. Is the maximum flow rate achieved by the patient during the FVC maneuver PEF < 100L/min : severe obstructive disease PEF= 100 to 200L/min : moderate obstructive disease PEF > 200L/min : mild obstructive disease
- 30. Indicates the respiratory muscle endurance Requires the patient to inhale and exhale as quickly as possible for a period of 12 secs Normal: 170L/min for healthy young adult
- 31. Pulmonary function abnormalities can be grouped into two main categories- • Obstructive • Restrictive
- 32. Obstructive defects: • Can occur in upper and larger airways or in smaller airways(less than 2mm) • Upper airways obstruction will reduce flow rates in the initial 25% of a FVC maneuver • Smaller airway obstruction will reduce flow rates in the later portion of the exhaled volume Restrictive defects: • Present when the lung volume are reduced to less than 80% of the predicted levels • Includes chest wall dysfunction, neurologic disorders, scarring of lung, obesity
- 36. Measurement Obstructive Restrictive FVC N or decrease Decrease FEV1 Decrease Decrease FEV1/FVC N or decrease N or increase FEF25%-75% Decrease N or decrease PEF Decrease N or decrease FEF50 Decrease N or decrease Slope of FV curve Decrease Increase MVV Decrease N or decrease
- 38. Based on the initial results of a baseline spirometry, additional testing of pulmonary mechanics is often desirable. If the baseline test indicates airway obstruction, determining the reversibility of obstruction is indicated. In the laboratory , FVC maneuver is often repeated after the patient has received a bronchodilator Reversibility is defined as 15% or greater improvement in FEV1
- 39. What is PFT & purpose of PFT. Indications & contra-indication. lung volumes & capacities. Flow – volume curve . Classification : obstructive & restrictive. Clinical interpretation.
- 40. 1. WHAT IS PFT AND ITS PURPOSE? 5MARKS 2. WRITE THE INDICATION AND CONTRAINDICATIONS OF THE PFT. 5MARKS