Disorders of Airways-Pulmonary Disorders Management and Guides Series

Disorders of Airways-Pulmonary Disorders Management and Guides

Disorders of Upper Airways

1.Acute obstruction of the upper airway

It can be immediately life-threatening and must be relieved promptly to avoid asphyxia.

Causes & Diagnosis

Acute upper airway obstruction causes include trauma to the larynx or pharynx, foreign body aspiration, laryngospasm, laryngeal oedema from thermal injury or angioedema, infections (acute epiglottitis, Ludwig angina, pharyngeal or retropharyngeal abscess), and acute allergic laryngitis.

2.Chronic obstruction of the upper airway

It may be caused by carcinoma of the pharynx or larynx, laryngeal or subglottic stenosis, laryngeal granulomas or webs, or bilateral vocal fold paralysis. Laryngeal or subglottic stenosis may become evident weeks or months after trans laryngeal endotracheal intubation. Inspiratory stridor, intercostal retractions on inspiration, a palpable inspiratory thrill over the larynx, and wheezing localized to the neck or trachea on auscultation are characteristic findings.

Diagnosis

Flow-volume loops may show characteristic flow limitations. Soft-tissue radiographs of the neck may show supraglottic or infraglottic narrowing. CT and MRI scans can reveal exact sites of obstruction. Flexible endoscopy may be diagnostic, but caution is necessary to avoid exacerbating upper airway edema and precipitating critical airway narrowing.

Vocal fold dysfunction syndrome

It is characterized by paradoxical vocal fold adduction, resulting in both acute and chronic upper airway obstruction.

Causes & Diagnosis

It can cause dyspnoea and wheezing that may be distinguished from asthma or exercise-induced asthma by the lack of response to bronchodilator therapy, normal spirometry immediately after an attack, spirometry evidence of upper airway obstruction, a negative bronchial provocation test, or direct visualization of adduction of the vocal folds on both inspiration and expiration. The condition appears to be psychogenic in nature.

Treatment

It consists of speech therapy, which uses breathing, voice, and neck relaxation exercises to abort the symptoms

Disorders of Lower Airways

1.Tracheal obstruction

Causes

It may be intrathoracic (below the suprasternal notch) or extrathoracic.Fixed tracheal obstruction may be caused by acquired or congenital tracheal stenosis, primary or secondary tracheal neoplasms, extrinsic compression (tumors of the lung, thymus, or thyroid; lymphadenopathy; congenital vascular rings; aneurysms; etc), foreign body aspiration, tracheal granulomas and papillomas, and tracheal trauma.Tracheomalacia, foreign body aspiration, and retained secretions may cause variable tracheal obstruction.

2.Acquired tracheal stenosis

Causes

It is usually secondary to tracheotomy or endotracheal intubation. Dyspnoea, cough, and inability to clear pulmonary secretions occur weeks to months after tracheal decannulation or extubating.

Diagnosis

Physical findings may be absent until tracheal diameter is reduced 50% or more, when wheezing, a palpable tracheal thrill, and harsh breath sounds may be detected. The diagnosis is usually confirmed by plain films or CT of the trachea. Complications include recurring pulmonary infection and life-threatening respiratory failure.

Management

It is directed toward ensuring adequate ventilation and oxygenation and avoiding manipulative procedures that may increase enema of the tracheal mucosa. Surgical reconstruction, endotracheal stent placement, or laser photo resection may be required.

3.Bronchial obstruction

Causes

It may be caused by retained pulmonary secretions, aspiration, foreign bodies, bronchomalacia, bronchogenic carcinoma, compression by extrinsic masses, and tumours metastatic to the airway.

Diagnosis & Management

Clinical and radiographic findings vary depending on the location of the obstruction and the degree of airway narrowing. Symptoms include dyspnoea, cough, wheezing, and, if infection is present, fever and chills. A history of recurrent pneumonia in the same lobe or segment or slow resolution (more than 3 months) of pneumonia on successive radiographs suggests the possibility of bronchial obstruction and the need for bronchoscopy. Radiographic findings include atelectasis (local parenchymal collapse), post obstructive infiltrates, and air trapping caused by unidirectional expiratory obstruction. CT scanning may demonstrate the nature and exact location of obstruction of the central bronchi. Bronchoscopy is the definitive diagnostic study, particularly if tumour or foreign body aspiration is suspected. The finding of bronchial breath sounds on physical examination or an air bronchogram on chest radiograph in an area of atelectasis rules out complete airway obstruction. Bronchoscopy is unlikely to be of therapeutic benefit in this situation.