Clinical approach to a patient with cough

A number of disorders of the respiratory tract and some even outside the respiratory tract can cause cough. A systematic approach towards a patient of chronic cough consisting of detailed history, physical examination of upper as well as lower respiratory tract, complete blood counts, tuberculin test, chest X-ray, and peak flow rate testing will give the diagnosis in majority of children. Pulmonary tuberculosis and asthma are the two commonest conditions diagnosed. If the initial work up is inconclusive, further laboratory testing and imaging studies should be considered. Thus, radiolabelled milk scan, barium swallow and 24-hour pH monitoring would diagnose gastroesophageal reflux. Spirometry, methacholine/exercise challenge test or a therapeutic trial may be required for confirming bronchial asthma. Flexible bronchoscopy is useful for evaluation for suspected aspiration syndromes and any anatomical or dynamic problem of the airway (e.g. tracheomalacia). Spiral and high resolution computed tomography (HRCT) along with magnetic resonance imaging are the modern day imaging techniques used for studying mediastinal masses, airway obstruction and even lung parenchyma (HRCT). Sputum examination for type of cells and bacteria can be useful, especially if pseudomonas or acid-fast bacilli are identified. Pseudomonas suggests cystic fibrosis (an uncommon disease in India) which can be confirmed by sweat chloride test and gene mutation studies.