PULMONARY FUNCTION TESTS

KHAZI ABDUL JABBARDEPT. OF OCCUPATIONAL DISEASES,

MEDICAL ACADEMY named after S. I. GEORGIEVSKY,CRIMEAN FEDERAL UNIVERSITY.

LEARNING OBJECTIVES:

General purpose for PFTs Types of PFTs Interpretation of different PFTs Knowing normal PFTs

PURPOSE OF PFTs:

Dx of symptomatic disease. Early screening for asymptomatic diseases. Prediction of prognosis. Monitoring of treatment.

PFTs helps us to classify diseases into 3 major subdivisions:

Obstructive lung disease: COPD, BA, CF & bronchiectasis. Restrictive lung disease: interstitial lung diseases (pulmonary fibrosis, sarcoidosis), chest wall pathologies, neuromuscular pathologies (ALS). Pulmonary vascular disease: primary pulmonary hypertension, ch. TED.

TYPES OF PFTs:

Routine: spirometry, lungs volume, diffusing capacity of CO-(abb:Dlco)

Specialized: arterial blood gas, oximetry, peak flow, exercise tests.

General understanding of lungs volumes:

SPIROMETRY:

How it is done?

Values that we will be calculating:

Flow volume loop:

Summary of values: FEV1:>3 L FVC:>4 L FEV1/FVC ratio: 60% Flow volume loop PERF: male(((ht*5.48)+1.58)-(age*0.041))*60 female(((ht*3.72)+2.24)-(age*0.03))*60 FEF25-75% With bronchodilator:

Interpretation of spirometry:

FEV1 FVC

FEV1/FVCRATIOTiffeneau Index.

OLDNORM/DECREASED

NORM/DECREASED

DECREASED(<70%)

RLDNORM/DECREASED

DECREASED INCREASED(>70%)

Flow volume loop:

Location of obstruction:

Stagine of COPD based on FEV1:GOLD classification based on FEV1 post bronchodilation.

GOLD STAGES FEV1 as per age/sex/height

1ST STAGE FEV1≥70%

2ND STAGE FEV1 ≤50 TO <80%

3RD STAGE FEV1 ≤30 TO <50%

4TH STAGE FEV1 <30%

LUNGS VOLUME TESTS:

Gas dilution methods- helium & nitrogen. Body plethysmography. Radiographic measurement.

Gas dilution test:

Imagine techniques:

From CXR measurements of lungs in PA & lateral views can be entered in algorithm to estimate lung volume.

Chest CT sliced section area multiplied with thickness can give probable volume of lung.

This type of technique is not accurate.

Interpretation of lung volumes:

DLCO:

It is used to measure the capacity of lungs to exchange gas.

A gas mixture of 0.3% carbon monoxide is used. Px is asked to take a breath & hold for about 10 sec & then exhale.

Helium is also add in test gas to measure the amount of lung volume used during gaseous exchange.

Summary:

Case:

Probable dx: ILD, most likely hypersensitivity pneumonitis.

END.ANY QUESTIONS?