|
|
||||||||
Guest Access | Sign In via User Name/Password |
|||||||||
* From Erasmus MC-Sophia Childrens Hospital, Erasmus University Medical Centre, Department of Pediatrics, Division of Pediatric Pulmonology, Rotterdam, the Netherlands.
Correspondence to: Ruben Boogaard, MD, Room Sb-2666, Sophia Childrens Hospital, Erasmus University Medical Centre Rotterdam, PO Box 2060, 3000 CB Rotterdam, the Netherlands; e-mail: r.boogaard{at}erasmusmc.nl
| Abstract |
|---|
|
|
|---|
Methods: We analyzed all flexible bronchoscopies performed between 1997 and 2004 in the Sophia Childrens Hospital, summarized clinical features of children with primary airway malacia, estimated the incidence of primary airway malacia, and calculated the predictive value of a clinical diagnosis of airway malacia by pediatric pulmonologists.
Results: In a total of 512 bronchoscopies, airway malacia was diagnosed in 160 children (94 males) at a median age of 4.0 years (range, 0 to 17 years). Airway malacia was classified as primary in 136 children and secondary in 24 children. The incidence of primary airway malacia was estimated to be at least 1 in 2,100. When pediatric pulmonologists expected to find airway malacia (based on symptoms, history, and lung function) prior to bronchoscopy, this was correct in 74% of the cases. In 52% of the airway malacia diagnoses, the diagnosis was not suspected prior to bronchoscopy. Presenting clinical features of children with airway malacia were variable and atypical, showing considerable overlap with features of allergic asthma. Peak expiratory flow was more reduced than FEV1.
Conclusion: Primary airway malacia is not rare in the general population, with an estimated incidence of at least 1 in 2,100 children. Airway malacia is difficult to recognize based on clinical features that show overlap with those of more common pulmonary diseases. We recommend bronchoscopy in patients with impaired exercise tolerance, recurrent lower airways infection, and therapy-resistant, irreversible, and/or atypical asthma to rule out airway malacia.
Key Words: bronchomalacia bronchoscopy child diagnosis difficult asthma incidence lung function symptoms tracheomalacia
| Introduction |
|---|
|
|
|---|
Children with mild airway malacia often present after the neonatal period with nonspecific symptoms such as rattling, wheeze, stridor, exercise intolerance, cough, recurrent lower airway infections, and airways obstruction.37 Because of the similarity in symptoms, the poor response to standard asthma treatment, and the irreversible nature of the airways obstruction, isolated airway malacia may be misdiagnosed for severe-persistent or therapy-resistant asthma.8910
Consequently, if airway malacia remains undetected in childhood, patients may be treated unnecessarily with high doses of inhaled corticosteroids into adulthood for many years, and may be undertreated for recurrent lower airways infections, with the risk of additional damage to the lung and airways.
Based on percentages between 23% and 57% of observed airway malacia in pediatric bronchoscopic series, various authors11121314 concluded that malacia of the central airways is more prevalent than previously thought, but general incidence data are lacking. This is partly due to the lack of an objective definition or classification of airway malacia371215 and the lack of noninvasive diagnostic tests.
Previous series121617 about children with airway malacia focused mainly on the association with other conditions and on airway malacia diagnosed in young infants. However, less is known about clinical features in children with primary airway malacia diagnosed during childhood. We therefore focused on children who underwent bronchoscopy after referral to our outpatient clinic with persistent pulmonary symptoms, but who were otherwise healthy. The aims of this study were to estimate the incidence of primary airway malacia in the general population, to estimate the predictive value of a clinical diagnosis of airway malacia by pediatric pulmonologists, and to characterize the presenting symptoms and findings in patients diagnosed with primary airway malacia.
| Materials and Methods |
|---|
|
|
|---|
Study Subjects
In a descriptive, retrospective study the indication and outcome of all flexible bronchoscopies performed by pediatric pulmonologists in our hospital between 1997 and 2004 were evaluated. The Erasmus MC-Sophia Childrens Hospital is a tertiary referral center for the southwest of the Netherlands with an adherence population of 4.4 million. Flexible pediatric bronchoscopies within this region are only carried out in this referral hospital.
Definitions
Primary airway malacia was defined as airway malacia in otherwise normal infants.7 Secondary airway malacia was defined as airway malacia secondary to esophageal atresia, VATER/VACTERL association (condition with vertebral anomalies, anal atresia, congenital heart disease, tracheoesophageal fistula or esophageal atresia, renourinary anomalies, or radial limb defects), vascular or other external compression of the airways, or specific syndromes.
Incidence and Clinical Features
The incidence of primary airway malacia was calculated assuming that malacia is congenitally present and not acquired, and that the annual detection rate of isolated airway malacia was fairly constant and thus reflecting the annual incidence in the population. In outpatients who underwent bronchoscopy because of diagnostic or therapeutic workup, we calculated the predictive value of a clinical diagnosis of airway malacia made by pediatric pulmonologists prior to bronchoscopy. In otherwise healthy patients with a diagnosis of primary airway malacia, we conducted a detailed review of the clinical features, including presenting symptoms and signs, lung function data, bacterial cultures and the lipid-laden macrophage index (LLMI)scored according to Corwin and Irwin18from the BAL fluid. Clinical features of patients with a concurrent medical condition such as cystic fibrosis (CF) or an immunologic disorder were not analyzed because we wanted to be informed about symptoms that could be attributed to the airway malacia.
Data from in-hospital bronchoscopies were excluded from these analyses, because we wanted to gain insight in the clinical features of patients who underwent bronchoscopy during a diagnostic workup at the outpatient clinic; in-hospital bronchoscopies are often performed in children with different pathologic conditions.
Bronchoscopic Examination
Bronchoscopies were carried out by a pediatric pulmonologist as part of diagnostic workup in routine patient care, using a flexible bronchoscope with external diameter 3.5 mm or 5.5 mm (Olympus; Tokyo, Japan) during general anesthesia. Airway malacia was diagnosed by visual inspection of airway shape and dynamics during spontaneous breathing without positive end-expiratory pressure, or during coughing. Malacia was defined as collapse of at least 50% of the airway lumen, during expiration, cough or spontaneous breathing, or a ratio of cartilage to membranous wall area of < 3:1.7 Bronchoscopies were recorded on videotape and reevaluated by at least one independent experienced pediatric pulmonologist. Only when consensus between observers existed on the diagnosis airway malacia, children were labeled as such. BAL was carried out according to recommendations,19 when lower airway infection and/or aspiration were expected on clinical grounds. Antibiotic treatment was discontinued 48 h in advance of bronchoscopy.
Statistics
All data are summarized using descriptive statistics.
| Results |
|---|
|
|
|---|
|
|
Incidence Estimate
Based on the annual birth rate of 50,000 in the region of adherence, assuming primary airway malacia as congenital, and a constant detection rate of 17 cases per year (136 cases in 7 years), it was estimated that the incidence of primary airway malacia was about 1 in every 2,600 newborns. An incidence estimate based on bronchoscopic findings from the last 4 years of the survey (from 2001 to 2004) was 1 in 2,100 children (95 cases in 4 years).
Predictive Value of a Clinically Expected Diagnosis of Airway Malacia Prior to Bronchoscopy
In the 324 out-of-clinic patients, airway malacia was found in 126 patients (115 cases of primary airway malacia). Prior to bronchoscopy, pediatric pulmonologists expected a malacia, based on history, physical examination, and/or lung function in 82 patients of whom 61 actually had malacia (positive predictive value, 74%). In 65 of 126 patients, airway malacia was not suspected prior to bronchoscopy (false-negative rate of 52%).
Primary Airway Malacia: Clinical Features
From the 115 patients with primary airway malacia diagnosed at the outpatient clinic, 96 patients (58 male) with a median age of 5.2 years (range, 0 to 16 years) had no concurrent medical conditions (isolated malacia). The presenting symptoms of those children are stated in Table 2
. Nineteen patients with primary airway malacia also had a concurrent medical condition (eg, CF, immunodeficiency, Down syndrome), probably influencing their presenting clinical features, and were therefore not analyzed.
|
Lung function was performed by 45 children (Table 3 ). Mean peak expiratory flow (PEF), FEV1, and FEV1/FVC were below predicted values. In most patients, lung function values did not improve with bronchodilatation. A typical flow-volume curve of a child with tracheomalacia is presented in Figure 2 .
|
|
| Discussion |
|---|
|
|
|---|
Other series111121314 also suggest that airway malacia is a relatively common disorder, but incidence estimates are not provided and differences in patient selection make it difficult to compare with these series. Moreover, a uniformly accepted definition of airway malacia is lacking and the bronchoscopic diagnosis of airway malacia is based on subjective evaluation by the bronchoscopist, making comparisons between studies difficult.
When pediatric pulmonologists expected to find a malacia prior to bronchoscopy, this was correct in three fourths of the patients. However, in one half of the patients with airway malacia, the diagnosis was not suspected prior to bronchoscopy. Hence, experienced specialized clinicians have difficulty in recognizing primary airway malacia based on clinical features. Furthermore, the most frequent presenting symptoms were cough, dyspnea, recurrent lower airways infection, recurrent rattling and wheeze, and reduced exercise tolerance, showing considerable overlap with features of asthma and chronic bronchitis. These factors imply that children with isolated airway malacia are easily misdiagnosed and treated for the wrong disease, such as asthma. This is supported by the fact that a large majority of the patients with airway malacia were using asthma medication at time of referral, while a pediatric pulmonologist diagnosed asthma in only 40% of these children. A typical, barking, or seal-like cough is often described as an indicative symptom in airway malacia2416 but was only mentioned in less than one half of the patients with isolated airway malacia.
In the majority of patients, we obtained positive bacterial culture findings in the BAL fluid, consistent with the clinical impression of chronic bacterial bronchitis secondary to the expected impaired mucociliary clearance in children with airway malacia.213
The LLMI was routinely assessed in the BAL fluid as an additional step in the diagnostic workup for aspirations. The large majority of the patients with isolated airway malacia had no evidence of aspirations based on the LLMI. These data are not consistent with reports31120 that suggest that aspiration is a frequent complication of airway malacia. The older age at diagnosis and the exclusion of patients with associated syndromes and medical conditions (who are at greater risk of aspiration) in our series may explain this difference.
Lung function measurements in patients with isolated airway malacia demonstrated airways obstruction not improving after bronchodilatation, with a considerable reduction of PEF, being much more affected than FEV1. The reduced PEF and FEV1 are compatible with the increased central airway collapsibility during forced expiration.
The limitation of this study is the retrospective nature of the survey that could have affected the accuracy of the data collection of clinical features from the medical records. However, at our department a standardized medical record is kept, in which presenting signs and symptoms are collected uniformly. Comparisons with other retrospective studies on airway malacia may be difficult because of differences in population and diagnostic protocols, definition of airway malacia, and application and availability of flexible bronchoscopy.
Tracheomalacia and bronchomalacia were the topic of an excellent and thorough recent review in CHEST.1 The present study provides some additional data and aspects of this disorder that are clinically relevant. According to the review article,1 mild-to-moderate airway malacia is a self-limiting disease and most infants outgrow the condition by the age of 2 years. In addition, it was stated that the delay from the onset of symptoms to diagnosis was not > 144 weeks.1 Our study demonstrates that a substantial number of cases are diagnosed much later in childhood. Possibly, this difference between the studies is explained by differences in clinical severity of malacia. Nevertheless, our study suggests that there are a considerable number of children with airway malacia, in whom the diagnosis is made relatively late in life or not at all, and that airway malacia can be very difficult to recognize.
High-speed multidetector CT and specialized imaging provide novel diagnostic possibilities to diagnose airway malacia noninvasively.21 This provides a diagnostic opportunity for children in whom invasive bronchoscopy cannot be performed. Nevertheless, in the majority of young children, bronchoscopy will be mandatory to diagnose airway malacia, because it is difficult to image the airway during dynamic maneuvers in young children due to their inability to perform breathing instructions.
What is the clinical relevance of this study? It suggests that the incidence of primary airway malacia is at least 1 in 2,100. Furthermore, it seems likely that a considerable proportion of pediatric (and probably adult) patients with atypical or recurrent respiratory symptoms, irreversible chronic airways obstruction labeled COPD or asthma,1022 or with persistent troublesome cough2324 do not have isolated airway malacia diagnosed. A correct diagnosis of airway malacia is important for several reasons: (1) the therapeutic approach is fundamentally different, being focused on treatment or prevention of lower airways infections and improvement of mucociliary clearance, sometimes even including surgery232526; (2) the patient and his/her family benefit from a sound explanation for the exercise intolerance (caused by the dynamic airway collapse) that may be present lifelong; (3) for both pediatrician and chest physician, the irreversibility of airways obstruction is sufficiently explained and will lead to less prescription of asthma drugs that are not necessary in most cases and may have side effects. Children with both asthma and airway malacia pose a therapeutic challenge. Lung deposition of inhaled corticosteroids may be negatively affected by severe airways obstruction and anatomic abnormalities, resulting in less efficacy of asthma treatment and worse long-term outcome, as was found in asthmatic patients who start off with lower lung function in childhood.22
We conclude that primary airway malacia is a common disorder in the general population. Many of our patients had bacterial lower airways infections but no indications of aspirations based on the bronchoscopic findings. The most striking lung function abnormality in our population was a decreased PEF, which appeared more affected than FEV1.
Presenting symptoms of isolated airway malacia are atypical and also for pediatric pulmonologists difficult to recognize. As a correct diagnosis is important because of the therapeutic implications and perhaps lifelong consequences, we recommend considering bronchoscopy in all patients with unexplained exercise intolerance, recurrent lower airways infection, and irreversible and/or atypical asthma.
| Footnotes |
|---|
This study was performed in the Sophia Childrens Hospital, Rotterdam.
Received for publication May 12, 2005. Accepted for publication May 30, 2005.
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
E. Yalcin, D. Dogru, U. Ozcelik, and N. Kiper Airway malacia disorders in children. Chest, July 1, 2006; 130(1): 304 - 304. [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |