Bronchomalacia and Tracheomalacia

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Chapter 381 Bronchomalacia and Tracheomalacia

Chondromalacias of the trachea or of a main bronchus occur when there is insufficient cartilage to maintain airway patency throughout the respiratory cycle and are common causes of persistent wheezing in infancy. Tracheomalacia and bronchomalacia can be either primary or secondary (see Table 381-1 on the Nelson Textbook of Pediatrics website at www.expertconsult.com). Although primary tracheomalacia and bronchomalacia are often seen in premature infants, most affected patients are born at term. Secondary tracheomalacia and bronchomalacia refers to the situation in which the central airway is compressed by adjacent structure (e.g., vascular ring, Chapter 426) or deficient in cartilage due to tracheoesophageal fistula. Laryngomalacia can accompany primary bronchomalacia or tracheomalacia. Involvement of the entire central airway (laryngotracheobronchomalacia) is also seen.

Table 381-1 CLASSIFICATION OF TRACHEOMALACIA

PRIMARY TRACHEOMALACIA

Congenital absence of tracheal-supporting cartilages

SECONDARY TRACHEOMALACIA

Esophageal atresia, tracheoesophageal fistula

Vascular rings (double aortic arch)

Tracheal compression from an aberrant innominate artery

Tracheal compression from mediastinal masses

Abnormally soft tracheal cartilages associated with connective tissue disorders

Prolonged mechanical ventilation, chronic lung disease

From McNamara VM, Crabbe DC: Tracheomalacia, Paediatr Respir Rev 5:147–154, 2004.

Clinical Manifestations

Primary tracheomalacia and bronchomalacia are principally disorders of infants, with a male:female ratio of 2 : 1. The dominant finding, low-pitched monophonic wheezing, is most prominent over the central airways. Parents often describe persistent respiratory congestion even in the absence of a viral respiratory infection. When the lesion involves only one main bronchus (more commonly the left), the wheezing is louder on that side. In cases of tracheomalacia, the wheeze is loudest over the trachea. Hyperinflation and/or subcostal retractions do not occur unless the patient also has asthma or another cause of small airways obstruction. In the absence of asthma, patients with tracheomalacia and bronchomalacia are not helped by administration of a bronchodilator. Acquired tracheomalacia and bronchomalacia are seen in association with vascular rings or tracheoesophageal fistula (and may persist after surgical correction) and cardiomegaly and after lung transplantation.

Diagnosis

The definitive diagnoses of tracheomalacia and bronchomalacia are established by flexible or rigid bronchoscopy (Fig. 381-1). The lesion is difficult to detect on plain radiographs, but fluoroscopy can demonstrate dynamic collapse and can avoid the need for invasive diagnostic techniques. Pulmonary function testing can show a pattern of decreased peak flow and flattening of the flow-volume loop. Other important diagnostic modalities include MRI and CT scanning. MRI with angiography is especially useful when there is a possibility of vascular ring and should be performed when a right aortic arch is seen on plain film radiography.

Figure 381-1 Images of tracheomalacia taken 10 mm from site. A, Saber-shaped or triangular appearance. B, Circumferential appearance. C, Crescent (lunate) appearance.

(From Masters IB, Zimmerman PV, Pandeya N, et al: Quantified tracheobronchomalacia disorders and their clinical profiles in children, Chest 133:461–467, 2008.)