Pulmonary Function Test
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Pulmonary function tests (PFTs) measure how well the lungs work by assessing lung volumes, air flow, and gas exchange. PFTs can help diagnose various respiratory diseases by detecting abnormalities. The tests involve spirometry to measure volumes of air inhaled and exhaled during normal and forced breathing maneuvers. Obstructive diseases reduce air flow, shown by a decreased FEV1 and FEV1/FVC ratio. Restrictive diseases limit lung expansion, shown by a reduced FVC but normal or increased FEV1/FVC ratio. PFTs are useful for evaluating respiratory function and monitoring treatment effects.
![• IC-max: amount of gas inspired in to the lungs after a
normal tidal exp: [IC=TV+IRV] 3500ml
• FRC-amount of gas remain in the lungs after normal
exp:[ FRC=ERV+RV] 2500ml
• VC-max: amount of gas expired from the lungs after a
max: insp: [VC=IRV+TV+ ERV] 4500ml
• TLC-max: amount of gas inspired to expand the lungs to
its max:extend [TLC=TV+IRV +ERV +RV] 6000ml
Lung capacity](https://image.slidesharecdn.com/pftrahul-180628050845/85/Pulmonary-Function-Test-8-320.jpg)
Pulmonary Function Test
- 1. PULMONARY FUNCTION TEST Rahul AP. Asst Proff, LIAHS BPT,MPT MIAP CRD&ICU Care
- 2. PFT • Pulmonary function tests (PFTs) are a group of tests that measure how well your lungs works, how well the lungs take in and exhale air, and how efficiently they transfer oxygen into the blood
- 3. • PFT or LFT are useful in assessing the functional status of the respiratory system both in physiological and pathological condition • It is base on the measurement of volumes of air breathed in and out in normal breathing and forced breathing • It is carried out by using a spirometer
- 6. Lung volume and capacities • Lung vol: are the static vol: of air breathed by an individual, ie vol: of air present in lung under specific position of the torax • 4 lung volumes • Depends on age, weight, gender and body position • 2 or more vol: when combined are capacity
- 7. Lung volumes • TV-the vol: of gas exchanged during a relaxed insp: followed by an exp: 500ml • IRV-extra vol: of gas that can be inspired above tidal insp: 3000ml • ERV-extra vol: of gas that can be expired after a normal tidal exp: 1000ml • RV-vol: of gas remain in lungs after a forceful exp: 1500ml
- 8. • IC-max: amount of gas inspired in to the lungs after a normal tidal exp: [IC=TV+IRV] 3500ml • FRC-amount of gas remain in the lungs after normal exp:[ FRC=ERV+RV] 2500ml • VC-max: amount of gas expired from the lungs after a max: insp: [VC=IRV+TV+ ERV] 4500ml • TLC-max: amount of gas inspired to expand the lungs to its max:extend [TLC=TV+IRV +ERV +RV] 6000ml Lung capacity
- 9. Graph
- 10. Mechanics of Breathing • Inspiration Active process • Expiration Quiet breathing: passive Can become active Pulmonary Function Tests Evaluates 1 or more major aspects of the respiratory system • Lung volumes • Airway function • Gas exchange
- 11. Indications/purpose • Detect disease, It serve as a diagnostic tool investigation role • Evaluate severity, extent and monitor the course of disease • Evaluate treatment • Measure effects and result of treatment exposures
- 12. PFTs can help diagnose • Asthma • Chronic bronchitis • Respiratory infections • Lung fibrosis • Bronchiectasis • Allergy
- 13. • Emphysema • Cystic fibrosis • Asbestosis which is a condition caused by exposure to asbestos • Sarcoidosis, which is an inflammation of your lungs, liver, lymph nodes, eyes, skin, or other tissues • Pulmonary tumor
- 14. Spirometry • It is an instrument for measuring the air capacity of the lungs • Measurement of the pattern of air movement in and out of the lungs during controlled ventilatory maneuvers. • spirometre is used to measure the air flow, ventilatory regulation, ventilatory mechanics and lung volume during a forced expiratory maneuver from full inspiration.
- 16. • Pft used to evaluate physiological aspect of breathing from resp:muscle function to the diffusion of gas at the alviolar wall. • Pft helps physiotherapist to distinguish between obstructive and restrictive lung problem and to select appropriate treatment • It also measure the effect of the given treatment.
- 17. Lung Factors Affecting Spirometry • Mechanical properties • Resistive elements
- 18. Mechanical Properties • Compliance –Describes the stiffness of the lungs –Change in volume over the change in pressure • Elastic recoil –The tendency of the lung to return to it’s resting state –A lung that is fully stretched has more elastic recoil and thus larger/ maximal flows of gas
- 19. Resistive Properties Affected by: Lung volume Age Sex Height Weight Race Disease Bronchial smooth muscles
- 20. PFT procedure • Forced expiratory maneuver is the common clinical approach • Results are found in patients chart/moniter • Common spirometric values areFEV1 and FVC FEV1/FVC ratio • Lung volume and peak expiratory flow rate (PEF or PEFR) are measured to differentiate obstructive or restrictive problems • Forced expiratory flow (FEF)
- 21. • Sit up straight • Get a good seal around the mouth piece • Rapid inhale maximally • Without any delay blow out as hard as fast as possible (blast out) • Continue the exhale until the patient can`t blow no more • Expiration should continue at least 6sec (in adult) and 3 sec (children under 10yrs) • Repeat at least 3 technically acceptable times (without cough, air leak and false start) Procedure
- 22. Normal spirogram
- 23. How to interpret abnormal PFT • If FVC&FEV1 is less than 80% (total vol:of air expelling is approx: 80% with in 1sec ie; FEV1) • Suggestions of some pathology, at this point and can`t decide obstructive/ restrictive problem
- 24. Forced expiratory volume in 1 second (FEV1) • FEV1 is the volume of air that can forcibly be blown out in one second, after full inspiration. • Average values for FEV1 in healthy people depend mainly on sex and age height and mass. • Values between 80% and 120% are considered normal.
- 25. Forced vital capacity (FVC) • Forced vital capacity(FVC) is the volume of air that can forcibly be blown out after full inspiration
- 26. FEV1/FVC ratio (FEV1%) • FEV1/FVC (FEV1%) is the ratio of FEV1 to FVC. In healthy adults this should be approximately 75–80%.
- 27. Forced expiratory flow (FEF) • Forced expiratory flow (FEF) is the flow (or speed) of air coming out of the lung during the middle portion of a forced expiration. • generally defined by fraction, The usual intervals are 25%, 50% and 75% (FEF25, FEF50 and FEF75)
- 28. Identify an obstructive problem • Obst: disorders (asthma, copd) air flow reduces because of narrowing of air ways • FEV1 is reduced • Spirogram is continued to 6 sec to empty lung, FVC also reduced because gas is trapped behind the obstructed bronchi • Cardinal feature of obstructive defect is reduction in the FEV1/FVC ratio
- 29. • In obstructive diseases (asthma, COPD, chronic bronchitis, emphysema) FEV1 is diminished because of increased airway resistance to expiratory flow. • The FVC may be decreased due to the premature closure of airway in expiration • This generates a reduced value (<80%, often 45%). 60-80% -mild 40-60% -moderate <40% -severe obstructions
- 32. Restrictive problem • Restrictive disorders can be cause by disease of the lung parenchyma (lung fibrosis) and chest wall disease(kyphoscoliosis) • This prevent the full expansion of the lungs therefore FVC may be reduced • FEV1 will increased because of the stiffness of the fibrotic lungs increases the expiratory pressure • Hence expired air comes out very quickly resulting with a high FEV1/FVC ratio
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