Patients with traumatic injury to the recurrent laryngeal nerve often have spontaneous improvement over time, usually within 3 to 6 months. If the paralyzed vocal cord has not recovered within 1 year of the injury, then it is likely to be permanently damaged. In some cases, Gelfoam injection of a paralyzed vocal cord can reposition the cord to improve phonation and airway protection. Patients with vocal cord paralysis resulting in severe airway obstruction and aspiration may require tracheostomy tube placement.
Chapter 136 u Lower Airway, Parenchymal, and Pulmonary Vascular Diseases 469
LOWER AIRWAY, PARENCHYMAL, AND PULMONARY VASCULAR DISEASES
There are many causes of lower airway diseases (Table 136-1).Lower airway diseases often result in airway obstruction. The most common lower airway disease in children is asthma, which results in diffuse bronchial obstruction from airway inflammation, constriction of bronchial smooth muscle, and excessive secretions. Virus-induced wheezing episodes are common, especially in children under 3 years of age. Wheezing that begins in the first weeks or months of life or that persists despite aggressive asthma therapy is likely not due to asthma, and further diagnostic evaluation may be warranted. Wheezing that is localized to one area of the chest suggests focal airway narrowing (foreign body aspiration or extrinsic compression by masses or lymph nodes).
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In contrast to upper airway obstruction, obstruction below the thoracic inlet causes more wheezing on expiration than on inspiration. A wheeze is a continuous sound that is produced by vibration of airway walls and generally has a more musical quality than does stridor. Intrathoracic pressure is increased relative to atmospheric pressure during exhalation, which tends to collapse the intrathoracic airways and accentuates airway narrowing on expiration. This manifests as expiratory wheeze, prolonged expiratory phase, and increased expiratory work of breathing. In patients with chronic airway infection (e.g., cystic fibrosis), the bronchi become permanently damaged and dilated (bronchiectasis). Patients with bronchiectasis have episodes of cough, often productive of purulent sputum, and may have inspiratory crackles.
When asthma is suspected, empiric trials of therapy (bronchodilators, short courses of oral corticosteroids, long-term use of inhaled corticosteroids) are useful in arriving at a diagnosis. In children older than 6 years, pulmonary function tests (spirometry) can assess airflow obstruction and response to bronchodilators. Radiographic evaluation is not needed with each episode of wheezing, but those with significant respiratory distress, fever, history consistent with foreign body
Bronchial edema Infection (e.g., bronchiolitis) Inhalation of irritant gases or particulates Increased pulmonary venous pressure
Bronchial hypersecretion Infection Inhalation of irritant gases or particulates Cholinergic drugs
Aspiration Foreign body Aspiration of gastric contents
Hypersensitivity reactions, allergic bronchopulmonary aspergillosis (seen only in children with either asthma or cystic fibrosis) Dynamic airway collapse
Airway compression by mass or blood vessel Vascular ring/sling Anomalous innominate artery Pulmonary artery dilatation (absent pulmonary valve) Bronchial or pulmonary cysts Lymph nodes (tuberculosis, lymphoma)