Pneumonia is a major cause of morbidity in children. In the United States, the incidence of pneumonia is 40 per 1,000 children younger than 5 years, decreasing to 9 per 1,000 children ages 9 to 15 years. Among these is a subset of children with recurrent pneumonia, the true incidence of which is unknown. Recurrent pneumonia is defined as two episodes of pneumonia within a 12-month period or three episodes at any time with radiographie clearing between episodes.1'2 Although every child with suspected pneumonia does not get a chest radiograph, the radiographie findings are necessary to determine whether the process is recurrent or persistent. Recurrent pneumonia is not an uncommon diagnosis in pediatrics and, as such, the pediatrician should have a systematic way of evaluating these children.
There are few studies of recurrent pneumonia in the pediatrie population. A recent review examined 2,952 children with pneumonia admitted to The Hospital for Sick Children in Toronto from 1987 through 1997.3 Approximately 8% of the patients met the criteria for recurrent pneumonia, and 92% of these had an underlying cause. Of these, 81% had been identified prior to the pneumonia, 11% were diagnosed during the first episode of pneumonia, and 8% were diagnosed after recurrence of pneumonia. Among the underlying causes were aspiration syndrome due to oropharyngeal incoordination (48%), immune disorder (10%), congenital cardiac disease (9%), asthma (8%), anatomic abnormalities (8%), gastroesophageal reflux disease (5%), and sickle cell anemia (4%). Asthma was the most common cause among those diagnosed after recurrent pneumonia had occurred. In an earlier review of 81 children with recurrent or persistent pneumonia, Eigen et al. found that 20 (25%) had an underlying predisposing condition.4 Of the 61 children without an underlying cause, 49% had a family history of allergies and asthma, 31% had a history of wheezing, and 18% were wheezing at the time of the initial evaluation. These findings suggest that asthma is a major cause of recurrent pneumonia in children.
When the pediatrician is faced with a child with suspected recurrent pneumonia, an underlying disease process should be sought with particular focus on general health status, known medical problems, the location of the pneumonia, and whether the pneumonia recurs in the same area of the lung. Very young children with recurrent pneumonia are more likely to have an anatomic abnormality, asthma, or gastroesophageal reflux disease. Children with neuromuscular diseases are at increased risk for recurrent aspiration syndrome and recurrent atelectasis. Failure to thrive, infections in other organs, or both suggest a possible immunodeficiency syndrome. Nocturnal respiratory symptoms may denote poorly controlled asthma or gastroesophageal reflux.
The extent of pneumonia, whether single or multiple lobes are involved, also helps in determining the etiology. When pneumonia recurs in the same lobe, an intraluminal obstruction, external compression, or anatomic abnormality is likely. Intraluminal obstruction is the most common cause of recurrent pneumonia affecting the same area of the lung. When pneumonia is diffuse or involves multiple lobes, aspiration, neuromuscular disease, gastroesophageal reflux and other esophageal abnormalities, immunodeficiency syndromes, or mucociliary impairment must be considered. Therapy must be guided by the likely diagnosis. For example, antibiotics are not helpful for asthma.
The pathogens that cause pneumonia depend on the age of the child, his or her immune status, and any underlying illness. In healthy children, several lines of defense protect the lungs from foreign substances and infectious agents. This starts with the filtration of particles in the nares, the epiglottal reflex (which prevents aspiration), the cough reflex (which expels aspirated substances), an active mucociliary clearance system, alveolar macrophages which engulf and kill bacteria), the immune system (which neutralizes bacteria), and the complex lymphatic system (which removes foreign particles from the lungs). When any one of these defense mechanisms breaks down, foreign materials and infectious agents are able to reach the lower airways. When organisms or other substances access the lower airways, the body responds by producing copious airway secretions and increased alveolar fluid, accompanied by infiltration of leukocytes. These processes result in pulmonary consolidation and hypoxemia from ventilation-perfusion mismatch, because poorly ventilated areas of the lung continue to be perfused. Eventually, macrophages actively remove bacteria and cellular debris, leading to improved aeration.
CLINICAL PRESENTATION AND EVALUATION
When recurrent pneumonia is a possibility, a careful history focusing on perinatal events, feeding difficulties, family, and environment is essential. An often forgotten part of the evaluation of children with lung disease is the history of environmental exposure to allergens, toxins, pollutants, and irritants such as tobacco smoke. Exposure to tobacco smoke over time depresses normal host defenses and predisposes to respiratory infections. The risk of exposure to respiratory infections from school contacts or siblings is important. A family history of asthma, allergies, or recurrent infections should be sought.
Cough, tachypnea, dyspnea, fever, and decreased appetite are the usual presenting symptoms. Other nonspecific findings include chills, headaches, vomiting, or abdominal pain. A child with recurrent pneumonia may not have the usual history of a viral prodrome preceding the other respiratory symptoms. Cough, tachypnea, or dyspnea may be either abrupt or insidious in onset. Fever is usually present. A thorough physical examination focusing on the respiratory system is essential. The examination may help to determine whether the respiratory disease is in one of the airways or the lung parenchyma. Careful auscultation may localize the problem to a specific area of the lung if focal disease is present. Other physical findings include use of accessory muscles, retractions, localized decreased aeration, wheezing, crackles, and dullness to percussion if the pneumonia is a focal process. An increased anteroposterior diameter of the chest suggests airway obstruction (eg, asthma or cystic fibrosis). Digital clubbing suggests bronchiectasis, such as with cystic fibrosis or ciliary dyskinesia. Allergic shiners and eczema point to allergies, with asthma causing recurrent pneumonia. Failure to thrive may be associated with immunodeficiency syndromes or cystic fibrosis.
Although the history and the physical examination may strongly suggest pneumonia, a chest radiograph should be obtained to evaluate the extent of pulmonary disease. Both frontal and lateral views of the chest should be examined. The radiographie findings provide the objective evidence needed to make the diagnosis of recurrent pneumonia. Without this radiographie evidence, it is impossible to determine whether the pathology is recurrent or persistent. Thus, it is essential to verify that previous diagnoses of pneumonia were supported by both clinical and radiographie evidence. Although every child with signs and symptoms of pneumonia does not get a chest radiograph, a chest radiograph is advised if the child is not healthy or an underlying condition is suspected. A thorough history, physical examination, and review of all available radiographs will enable the physician to confirm the diagnosis of recurrent pneumonia and suggest other diagnostic tests based on predisposing factors.
With the first episode of pneumonia, an extensive workup is not required. With recurrent pneumonia, however, further diagnostic evaluation is needed. The nature and the extent of pneumonia guides the intensity of the evaluation. A complete blood cell count, erythrocyte sedimentation rate, and blood cultures in young children might be helpful acutely. Pulmonary function testing offers objective measures of lung function and can help diagnose asthma. Chest radiographs during the acute illness and convalescence are necessary to determine whether the initial findings clear and recur or persist.
Specific laboratory evaluation depends on the suspected cause of the recurrent pneumonia. If there is diffuse disease with bronchiectasis, a sweat test must be done to rule out cystic fibrosis. However, in a neurologically impaired child with diffuse infiltrates on chest radiograph, the leading diagnosis is aspiration syndrome resulting from impaired swallowing, gastroesophageal reflux disease, or both. In this case, a pH probe study, barium swallow, flexible endoscopie evaluation of swallowing and sensory testing (FEESST), or all three are most appropriate. Table 1 outlines the evaluation of recurrent pneumonia.
Evaluation of Recurrent Pneumonia
Causes of Recurrent Pneumonia In the Same Area of the Lung
RECURRENT PNEUMONIA IN THE SAME AREA OF THE LUNG
When pneumonia recurs in the same area of the lung, the etiology is likely a focal process, such as intraluminal obstruction, external compression, or an anatomic abnormality. Of these, obstruction of the airway lumen is the most common cause. Table 2 lists some of the causes of recurrent pneumonia involving either a single lobe or the same anatomic area in children.
The most common intraluminal obstruction in children is caused by aspiration of a foreign body. The peak age of foreign body aspiration is between 6 months and 3 years.5 Food products such as peanuts, carrots, and corn are the most common offending agents. However, candy wrappers, small plastic toys, coins, and earrings may become lodged in the airway. Although two-thirds of foreign bodies are found within 1 week of the aspiration, one-third go undetected for more than 1 week.2 Following aspiration of a foreign body, symptoms may occur quickly or may lag for days or weeks. Once the child is brought to the attention of a physician and treated with antibiotics, he or she typically improves, but the symptoms recur if the foreign body is not removed. A chest radiograph will show infiltrates, and the child is again treated for pneumonia. An astute physician will recognize this pattern and, particularly if the patient is an infant or toddler, will focus the history taking on possible preceding events that could be associated with aspiration, including coughing or choking with feeding. If a coughing or choking event was witnessed, the case can be managed efficiently and appropriately. The child should be referred for rigid bronchoscopy. Often cases of aspiration are not witnessed or there is a period of time without clinical symptoms and the initial aspiration event is forgotten or not associated with the new onset of symptoms.
In addition to foreign bodies, mucoid impaction, bronchomalacia, and stenosis all predispose to pneumonia by obstructing the airway. Tumors (eg, bronchial adenomas) are rare in children, but they often present as recurrent pneumonia with the tumor detected via bronchoscopy.6 Bronchial adenomas or slow-growing malignant tumors (eg, mucoepidermoid carcinomas) are completely treated by resection.
External Compression of the Airway
External compression of the airway may be caused by enlarged lymph nodes or, rarely, an enlarged heart. Lymphadenopathy is associated with pulmonary infections such as tuberculosis, histoplasmosis, or coccidioidomycosis. In tuberculosis, the right middle lobe is most likely to be affected because it is a narrow orifice surrounded by nodes. Enlargement of the nodes can lead to airway obstruction. Lymphoma also causes enlargement of lymph nodes that can impinge on the airway, resulting in obstruction that leads to pneumonia.
The anatomic abnormalities associated with recurrent pneumonia include airway stenosis or malacia, pulmonary sequestration, congenital lobar emphysema, bronchogenic cysts, and cystic adenomatoid malformation.7 When a structural abnormality leads to recurrent pneumonia, surgical intervention is appropriate because recurrent pneumonia causes recurrent inflammation that can lead to progressively worsening lung function or reinfection with more virulent organisms.
EVALUATION OF RECURRENT PNEUMONIA IN A SINGLE AREA
The diagnostic (and sometimes therapeutic) approach to the child with recurrent focal pneumonia includes bronchoscopy to evaluate directly for intraluminal obstruction or external compression of the airway. Some anatomic defects can also be found using bronchoscopy. Bronchoscopy will also allow removal of a foreign body, biopsy of bronchial adenoma, and cultures of secretions. If bronchoscopy is not diagnostic, a computerized tomography scan of the chest often provides information regarding the distal airways and the extent of lung disease. Magnetic resonance imaging or angiography may detect a vascular ring or sling or an anomalous vessel feeding a sequestered lung.
Recurren! Pneumonia Involving Multiplo Lobes
When faced with a patient who has recurrent pneumonia in multiple lobes (diffuse), the physician should look for evidence of an underlying disease, particularly neuromuscular disorders, suck and swallow defects that could predispose to recurrent aspiration, asthma, immunodeficiency syndrome, mucociliary dysfunction, anatomic abnormalities, and cardiac disease. Table 3 lists some of the causes of recurrent pneumonia involving multiple lobes.
The most common cause of recurrent pneumonia in hospitalized children is aspiration. Recurrent pneumonia secondary to aspiration may be associated with abnormal swallowing, gastroesophageal reflux, or both, especially in children with neuromuscular disease and seizure disorders.8 Anatomic defects such as cleft palate can also lead to impaired swallowing and aspiration. The difficulty with diagnosing aspiration pneumonia occurs when the aspiration of small amounts of saliva or food is chronic. Barium swallow may show abnormal swallowing, but is not sensitive in detecting chronic aspiration of small quantities of secretions or food. A pH probe can confirm gastroesophageal reflux, but does not provide specific information about aspiration. FEESST allows for direct assessment of the motor and sensory aspects of swallowing to determine the risk of aspiration.9 Laryngopharyngeal reflux can also be assessed by FEESST. Another test that may help to detect aspiration is quantification of lipid-laden macrophages. The specimen is obtained by bronchoalveolar lavage.
Causes of Recurrent Pneumonia In Multiple Areas of the Lung
The radiograph of a child with asthma often shows multiple areas of atelectasis from mucous plugging of the airways. The physiologic characteristics of asthma, namely airway narrowing due to bronchoconstriction and airway inflammation resulting in increased mucous production, lead to atelectasis. If an asthma exacerbation is triggered by a viral upper respiratory tract infection, the child may have an associated fever. The child presents with diffuse wheezing, fever, and a chest radiograph that shows multiple opacities. The clinical presentation and radiographie findings may lead to a diagnosis of pneumonia. Unfortunately, this too often results in emphasis on antibiotic treatment when the more effective treatment is anti-inflammatory therapy to decrease mucous production, mucous plugging, and atelectasis.
Most children with recurrent pneumonia do not have an immunodeficiency syndrome, An immunologie workup should be considered for a child with other unusual or prolonged infections. A screening evaluation for possible immunodeficiency includes serum IgA, IgG, IgM, and IgE, a complete blood cell count with differential, and skin testing for delayed hypersensitivity reactions with Candida. Serum IgG subclasses may be useful, particularly because IgG2 deficiency is associated with recurrent pulmonary infections, especially when combined with IgA deficiency.10 Other possible studies include T- and B-cell studies, human immunodeficiency virus testing, and serum complement levels.11 With a complement deficiency or defect in complement activation, the child is at increased risk for infection by encapsulated organisms.
Cystic fibrosis and ciliary dyskinesia are the leading causes of mucociliary dysfunction in children. When a child presents with recurrent pneumonia, cystic fibrosis must be considered. The lungs of a child with cystic fibrosis are characterized by thick, tenacious mucous that is difficult to mobilize. Sputum often contains Staphylococcus aureus or Pseudomonas aeruginosa. Ciliary dyskinesia also causes difficulty in mobilizing secretions, but the mucous is normal. Congenital ultrastructural defects of the cilia can lead to ciliary dysfunction.12 Stasis of secretions leads to pneumonia in both cases.
When the pediatrician is faced with a child with suspected recurrent pneumonia, the radiographs provide important clues. Reviewing the radiographs with an experienced radiologist will help to establish whether the lung disease is recurrent or persistent and whether there is a diffuse or focal process. Once the radiographs confirm recurrent disease, the pediatrician should start an investigation for an underlying disorder, remembering that in an otherwise healthy child asthma is a leading causing of recurrent infiltrates. A careful history and physical examination and pulmonary function testing will often confirm the diagnosis and eliminate the need for further evaluation.
1. Wald ER. Recurrent and nonresolving pneumonia in children. Semin Respir Infect. 1993;8:46-58.
2. Wald ER. Recurrent pneumonia in children. Adv Pediatr infect Dis. 1990;5:183-203.
3. Owayed AF, Campbell DM, Wang EE. Underlying causes of recurrent pneumonia in children. Arch Pediatr Adolesc Mea. 2000;154:190-194.
4. Eigen H, Laughlin JJ, Homrighausen J. Recurrent pneumonia in children and its relationship to bronchial hyperreactivity. Pediatrics. 1982;70:698-704.
5. Wunsch R, Wunsch C, Darge K. Foreign body aspiration. Radiologe. 1999;39:467-471.
6. Helin I, Tedgard U, Dejmek A, Lindgren S. Muco-epidermoid tumour of the bronchus. Int ] Pediatr Otorhinolaryngol. 1984,7:289-295.
7. Kravitz RM. Congenital malformations of the lung. Pediatr Clin North Am. 1994;1:453472.
8. Bauer ML, Figueroa-Colon R, Georgeson K, Young DW. Chronic pulmonary aspiration in children. South Med /. 1993;86: 789-795.
9. Link DT, Willging JP, Miller CK, Cotton RT. Rudolph CD. Pediatrie laryngopharyngeal sensory testing during flexible endoscopie evaluation of swallowing: feasible and correlative. Ann Otol Rhinol Laryngol. 2000;109:899-905.
10. Shackelford PG, Polmar SH, Mayus JL, Johnson WL, Corry JM, Nahm MH. Spectrum of IgG2 subclass deficiency in children with recurrent infections: prospective study. J Pediatr. 1986;108:647-653.
11. Sheikh S, Madiraju K, Steiner P, Rao M. Bronchiectasis in pediatrie AIDS. Chest. 1997;112:1202-1207.
12. Armengot M, Escribano A, Carda C, Basterra J. Clinical and ultrastructural correlations in nasal mucociliary function observed in children with recurrent airways infections, bit} Pediatr Otorhinoiaryngol. 1995;32:143-151.
Evaluation of Recurrent Pneumonia
Causes of Recurrent Pneumonia In the Same Area of the Lung
Causes of Recurrent Pneumonia In Multiple Areas of the Lung