Investigations in Respiratory Diseases and The Lung Function Tests Dr.Dhaher JS Al-habbo FRCP London UK Professor in Medicine and Respiratory Diseases DEPARTMENT OF MEDICINE

Imaging: The Plain chest radiograph: 1-Pneumonia, Bronchogenic carcinoma, Pulmonary Tuberculosis, and Pleural Effusion can be detected very easily by Plain radiograph. 2-Lateral Film provides additional information about the nature and position of the lung lesion. 3-Follow up chest radiograph is very useful for monitoring the progress of the disease and the advantage of the therapeutic regimen.

Flat opacified line at the right hemidiaphragm characteristic of an effusion. The upper surface of the right middle lobe fissure is more sharply visible

Imaging cont Computed Tomography of the chest is very sensitive and accurate in determining the position, the size, and the consistency (calcification or cavitation) of any mass lesion. Pre-operative assessment of mediastinal spread in patients with lung cancer. High-resolution CT is very useful in diagnosis of interstitial fibrosis, bronchiectasis and pulmonary embolism.

Pleural effusion CTScan of thorax

Ventilation-perfusion Imaging cont….. 133Xe gas is inhaled (ventilation scan) . 99mTc-labelled albumin are injected I.V (perfusion scan); Pulmonary embolism we will detect filling-defect in the perfusion scan and doesn't match the ventilation scan . Asthma and COPD will show a matched Ventilation-perfusion defect.

Lung ventilation and perfusions cintigraphy

Imaging cont….. Positron emission tomography (PET) whole-body PET[18_fluorodeoxyglucose(FDG)] very useful in staging lung cancer. Pulmonary angiography for the positive detection of pulmonary embolism.

Endoscopic Examination and others Laryngoscopy Direct or indirect examination. Bronchoscopy Mediastinoscopy Pleural aspiration and biopsy Skin tests; Tuberclin test and skin hypersensitivity tests Immunological and serological tests

Other tests Counter-immunoelectrophoresis of Sputum, blood or urine (e.g. for pneumococcal antigen). Blood for antibody titres for specific organisms(Mycoplasma,legionella,chlamedia or viruses).Preciptating antibodies for fungi e.g Aspergillus. Microbiological investigations. Histopathological investigations

Pulmonary Function Testing Purpose of Pulmonary Function Testing is to know 1-How much air volume can be moved in and out of the lungs 2-How fast the air in the lungs can be moved in and out 3-How stiff are the lungs and chest wall 4-The diffusion characteristics of the membrane through which the gas moves (determined by special tests) 5-How the lungs respond to chest physical therapy procedures

The commonly used Lung function tests Forced Vital Capacity FVC: - This is the total amount of air that you can forcibly blow out after full inspiration, measured in liters. Forced Expiratory Volume in 1 Second FEV 1: - The amount of air that you can forcibly blow out in one second, measured in liters. These two tests considered one of the primary indicators for the lung function test.

FEV 1 / FVC - This is the ratio of FEV 1 and FVC, to determine the amount of the FVC that can be expelled in one second. In healthy adults this should be approximately 80%. Peak Expiratory Flow PEF: - The speed of the air moving out of your lungs at the beginning of the expiration, measured in liters per second.

FEF 25-75% or 25-50%: Forced Expiratory Flow 25-75% or 25-50% This is the average flow (or speed) of air coming out of the lung during the middle portion of the expiration (sometimes referred as the maximal mid-expiratory flow MMEF).

Forced Inspirtory FIF 25-75% or 25-50%: Flow 25%-75% or 25%-50% - This is similar to FEF 25%-75% or 25%-50% except the measurement is taken during inspiration. Forced Expiratory Time FET: - This measures the length of the expiration in seconds.

Flow volume loop Normal flow volume loop has a rapid peak expiratory flow rate . Gradual decline in flow back to zero. The Inspiratory portion of the loop is a deep curve plotted on the negative portion of the flow axis.

Obstructive Lung Disease FEV1 is reduced disproportionately more than the FVC resulting in an FEV1/FVC ratio less than 70 - 80%. This reduced ratio is the primary criteria for diagnosing obstructive lung disease by spirometry. FEV1 > 80% predicted normal 65 - 80% mild 50 - 65% moderate < 50% severe

Extrathoracic airway obstruction Expiratory flow-volume curve is normal Inspiratory flow reaches a low plateau value. Typically the FVC and FEV1 are in the normal range . The pattern of the expiratory flow-volume curve is normal the high pressure in extrathoracic airways distends the airway . upper airway obstruction example due to paralysis of the vocal cords.

The End