Evaluation of recurrent pneumonia.

The incidence of community-acquired pneumonia in children ranges from 15 to 40/1000 children in developed countries. Recurrent pneumonia is defined as 2 episodes in a single year or 3 episodes ever, with radiographic clearing of densities between occurrences. By this definition, recurrent pneumonia occurs in 7.7–9% of all children with pneumonia. There is no single common cause for recurrent pneumonia. In one series, 40% of 81 children had asthma, 10% had aspiration and 5% had immunodeficiency syndromes. Similarly in 60 of 71 hospitalized children with a known underlying condition, 32% had asthma, 15% had gastroesophageal reflux, 10% had immunodeficiency and 3% had aspiration syndromes. In contrast, series from Canada and India found aspiration to be the leading cause. Evaluation and treatment depends on whether disease recurs in the same or different regions. Densities recurring in the same region imply a localized area of intraluminal obstruction, extraluminal compression or structural abnormalities of the airway or lung parenchyma. The most common cause for intraluminal obstruction in children is a retained foreign body. Extraluminal compression results from enlarged lymph nodes, enlarged or aberrant vessels, or parenchymal tumors. Structural airway abnormalities include localized bronchial stenosis or bronchomalacia, tracheobronchus or isolated areas of bronchiectasis. Parenchymal lesions include pulmonary sequestration, cystic adenomatoid malformation and bronchogenic cysts. Right middle lobe syndrome is a unique entity of recurrent right middle lobe pneumonia and atelectasis. That lobe is prone to infection and collapse because the bronchus arises from the bronchus intermedius at an acute angle and is relatively long before it subdivides into segments. Adjacent lymph nodes can compress it when they enlarge. Finally there is no collateral ventilation between the right middle lobe and other lobes. The most common noninfectious cause of right middle lobe syndrome is asthma; tuberculosis remains the most common infectious etiology. Evaluation of recurrent pneumonia in a single region begins with airway endoscopy. Direct visualization detects dynamic airway collapse and identifies lesions as distal as subsegmental bronchi. Samples from airways or alveolar spaces can be obtained for culture and cytologic examination. For distal lesions or those outside of the airway lumen, chest computerized tomography, magnetic resonance imaging and angiography are useful. These modalities have largely supplanted angiography and bronchography. When lymphadenopathy is present, tuberculin skin testing should be performed. If there is a suggestive history, acute and convalescent titers for histoplasmosis, blastomycosis or coccidioidomycosis should be obtained. Children who develop recurrent pneumonia in varying lobes may have impairment in cough or mucociliary clearance mechanisms, diffuse airway narrowing that hampers airway clearance or local or systemic immune dysfunction. Aspiration “from above” is associated with impaired cough and diffuse airway narrowing. It results from swallowing dysfunction, due to central nervous system abnormality, neuromuscular disease or anatomic lesion of the oropharynx. A history of coughing during feedings should provoke evaluation From the University of Pennsylvania School of Medicine and The Children’s Hospital of Philadelphia, Philadelphia, PA Copyright © 2005 by Lippincott Williams & Wilkins ISSN: 0891-3668/05/2403-0265 DOI: 10.1097/01.inf. 0000156419.60574. 16 CONTENTS Evaluation of Recurrent Pneumonia Probiotics and the Treatment of Infectious Diarrhea