Tracheomalacia and Bronchomalacia

Tracheomalacia describes softening of the tracheal cartilages, with consequent obstruction. The subject is itself "soft" and not a little confusing. Tracheomalacia is a consequence of multiple processes, some well defined clinically, but of poorly understood etiology. The lesions are rare and there are differences of opinion about their nature. For the most part, management ranges from difficult to experimental or currently impossible. The degree of loss of normal semirigidity of cartilages may be partial or complete, and may involve the entire trachea or a segment of it.

Congenital tracheomalacia is presented in Chapter 6, "Congenital and Acquired Tracheal Lesions in Children" (see Figure 6-11). Not truly congenital, but of genetic origin, is tracheomalacia seen in patients with dwarfism due to achondroplasia. Three such patients had softened tracheal cartilages with easy collapse. In addition, the trachea had failed to grow in length or diameter as they became adults, so that the lumen was infantile and easily occluded. Each had already undergone a number of surgical procedures in childhood, including high tracheostomy with injury to the cricoid and to the subglottic larynx, tracheostomy with stenosis and/or granulomas, and failed tracheal resections. A prognathous jaw and limitation of cervical mobility in these patients can make rigid bronchoscopy (eg, for granuloma removal) impossible, unless there is an existing tracheostomy. Intubation, if necessary, can be done with some difficulty over a flexible bronchoscope. Because of the small diameter of the airway, a laryngeal mask airway (through which a flexible bronchoscope can be introduced) seems preferable. Each patient will present unique problems. If surgical reconstruction seems inadvisable in a given situation, recourse to a tracheostomy or T tube may be necessary. The latter may not be successful for the long term if the airway, and consequently the T tube, is too narrow (see Chapter 39, "Tracheal T Tubes").

Acquired segmental tracheomalacia ("focal" tracheomalacia) resulting from postintubation injury has been considered in Chapter 11, "Postintubation Stenosis" (Figure 15-1). Secondary malacia resulting from extrinsic compression by lesions such as goiter, tumors, and vascular structures is described subsequently in

figure 15-1 Localized tracheomalacia in a 16-year-old male, resulting from prolonged ventilation for several months, via a tracheostomy, subsequent to severe head injury, coma, and multiple complications. In addition to a distal 2.5 cm long circumferential stenosis due to cuff injury 2 cm below a stoma, he had a 2 to 3 cm segment of malacia of the anterior tracheal wall above the stoma from prolonged pressure by the tracheostomy tube during ventilation. A, Lateral neck roentgenogram shows an apparently normal upper tracheal air column with the patient at rest. Stenosis is distal and not visualized in this roentgenogram. Calcification in larynx is visible superiorly. B, Forced inspiration shows collapse of the soft anterior tracheal wall (arrow). C, On expiration, the anterior tracheal wall is distended. After circumferential resection of the distal stenosis, obstruction was apparent due to the malacic trachea. Through a separate small incision, a perforated polypropylene ring was inserted to encircle and support the soft segment. Excision of both lesions in continuity would have been too long to allow a safe anastomosis. Two separate excisions would have endangered the blood supply of the short intervening segment of the trachea. Two-stage resection would also have been possible. This patient's airway remains excellent 32 years later.

figure 15-1 Localized tracheomalacia in a 16-year-old male, resulting from prolonged ventilation for several months, via a tracheostomy, subsequent to severe head injury, coma, and multiple complications. In addition to a distal 2.5 cm long circumferential stenosis due to cuff injury 2 cm below a stoma, he had a 2 to 3 cm segment of malacia of the anterior tracheal wall above the stoma from prolonged pressure by the tracheostomy tube during ventilation. A, Lateral neck roentgenogram shows an apparently normal upper tracheal air column with the patient at rest. Stenosis is distal and not visualized in this roentgenogram. Calcification in larynx is visible superiorly. B, Forced inspiration shows collapse of the soft anterior tracheal wall (arrow). C, On expiration, the anterior tracheal wall is distended. After circumferential resection of the distal stenosis, obstruction was apparent due to the malacic trachea. Through a separate small incision, a perforated polypropylene ring was inserted to encircle and support the soft segment. Excision of both lesions in continuity would have been too long to allow a safe anastomosis. Two separate excisions would have endangered the blood supply of the short intervening segment of the trachea. Two-stage resection would also have been possible. This patient's airway remains excellent 32 years later.

this chapter. Obstruction resulting from relapsing polychondritis was discussed in Chapter 14, "Infectious, Inflammatory, Infiltrative, Idiopathic, and Miscellaneous Tracheal Lesions." Two additional categories of intrinsic malacia are to be considered. The first is partial malacia, usually associated with chronic obstructive pulmonary disease (COPD), which can lead to severe expiratory collapse of the lower trachea and main bronchi. The second is the very rare occurrence of idiopathic complete malacia of tracheal cartilages.

Tracheal and bronchial malacia, most often associated with COPD, seems to occur infrequently. It varies in severity and may well be underdiagnosed, since COPD may seem to be sufficient cause for respiratory distress. It is also difficult to distinguish symptomatically from chronic asthmatic bronchitis. Patients complain of dyspnea, particularly in the expiratory phase, and this is especially manifest on effort. Respiratory crises that border on asphyxia may follow bouts of severe coughing. Seizures may occur, which in the past were termed "laryngeal epilepsy." Expiratory stridor is heard; cough may be intractable. The harder the patient works to breathe, the more difficult it becomes. Secretions are raised with difficulty, often a leading complaint, because the cough is weak. The cough is characterized by a "seal bark" quality. Recurrent respiratory infections ensue.

A history of pulmonary disease usually precedes the finding of tracheal disease. These changes are well identified by flexible bronchoscopy in a conscious patient, where dynamic changes with respiration and cough can be elicited and observed. This type of severe expiratory tracheobronchial collapse occurs most often in males over the age of 40 years. Diminution in elastic fibers of the membranous wall has been found in these patients, but may well be a secondary change.1 The factors that lead to this deformity and its association with COPD remain unknown.

Bronchoscopic examination reveals a flattening of cartilages from a normal "C" configuration (Figure 15-2). The ends of the cartilages may curve slightly forward, so that the cartilages assume the configuration of an archer's bow. The membranous wall is elongated. On expiration, especially with forced respiration and cough, the cartilage flattens out even more and the membranous wall approximates toward the anterior wall. Complete or nearly complete tracheal occlusion results. The lower two-thirds of the trachea (the intrathoracic portion) and both main bronchi are most often involved. Sometimes, the malacia extends to more distal bronchi.

Fluoroscopy demonstrates anteroposterior tracheal occlusion, and inspiratory-expiratory computed tomography (CT) scan confirms this dynamic obstruction (Figure 15-3). Cross-sectional area normally reduces by 13 to 14% in the upper- and midtrachea on forced expiration. The degree of dynamic collapse in acquired tracheomalacia was measured by semiautomated CT cross-sectional area calculations by Aquino and colleagues.2 For patients with tracheomalacia, the mean change in the upper trachea was 47% and was 54% for midtrachea. A greater than 30% change was 94% sensitive in detecting malacia. Most patients have advanced COPD with emphysematous change visible on images.

Herzog and colleagues studied in detail the pathophysiology of expiratory obstruction in chronic lung disease, in patients who demonstrated "dyskinesia" of the trachea and main bronchi.3 They theorized that major intrathoracic airways were no longer held open in the expiratory phase of respiration due to loss of tissue elasticity. Expiratory airflow is consequently markedly reduced. Because of the collapse, a marked pressure gradient results between intra-airway pressure in the subglottic region and that at the carinal and main bronchial levels. Rate of progression of malacia is variable, but spontaneous improvement does not happen.

In an effort to improve this mechanical deficit, Herzog and Nissen narrowed and splinted the membranous wall of the lower trachea and the main bronchi, using various materials.4 The ends of the cartilages were pulled to the edges of longitudinal splints fixed to the membranous wall, thus restoring a more normal horseshoe shape to the softened but still functional cartilage. Criteria for possible operative intervention, in addition to the clinical signs noted and bronchoscopic and imaging data, which were recommended by Herzog and colleagues, are 1) a forced expiratory volume in 1 second (FEVi) of less than 40% of vital capacity indicating severe obstruction, and 2) an increase in central airway resistance over 20 cm H2O per liter per second at an alveolar pressure of 60 cm H2O (the pressure developed by moderately strong cough).3 Herzog and colleagues further stated that "intractable cough due to (bronchoscopically observed) circumscribed contact of the membrane with the anterior wall of the trachea or main bronchi is an absolute indication for local stabilization of the membranous wall."3 Inability to raise secretions because of collapse is a relative indication. Herzog and Rossetti reported success in treating 17 patients.5 Respiratory function improved, as well as ease of expectoration, dyspneic crises were ameliorated, and patients were able to increase their physical activities. Although the basic pulmonary disease was not improved, some patients seemed to obtain significant palliation. Other reports are less encouraging.6 Little systematic data has been reported. The long-term effectiveness of such procedures remains unclear. Complicating these issues are the progression of underlying COPD, presence of distal bronchial collapse, and also the variety of techniques of splinting employed.

Different materials have been used for the posterior splints: fascia lata, pericardium, perforated rigid plastic strips, lyophilized bone, and Goretex. Circumferential wrapping of the trachea and both main bronchi with heavy Marlex, using tissue adhesive, was reported to be successful, but raises concern about tracheal blood supply if more generally employed.71 was initially impressed with the ease of use and apparent effectiveness of Goretex strips for obtaining correction. However, since Goretex does not become incorporated by the tissues, late failure followed, due to partial separation of the Goretex from the membranous wall of the trachea. Sterile fluid collected between the Goretex and the membranous wall, producing obstruction. I subsequently used pericardium, but this appeared to remodel

Tracheomalacia And Bronchomalacia

figure 15-2 Bronchoscopic observations in tracheobronchomalacia with expiratory obstruction, in a 40-year-old diabetic man with dyspnea on effort, cough, inability to clear secretions, and frequent respiratory infections. A, View from cricoid down clearly showing the transition from C-shaped tracheal cartilages to marked flattening and splaying distally. B, Midtrachea in the same patient. Cough occluded the airway completely. Also, see Figure 39, Color Plate 16. C, Inspiratory view of the lower trachea in another patient with severe malacia. Note the viscid secretions. D, Expiratory view. Fully obstructed. E, Stable lower trachea after posterior membranous wall tracheoplasty. The membranous wall shows typical post-tracheoplasty irregularity.

with time, attenuate, and lose effectiveness. Marlex mesh has proved very satisfactory, since it causes sufficient inflammatory reaction, and is of porous structure which ensures permanent incorporation by fibrous tissue ingrowth (Figure 15-4) (see Chapter 32, "Surgery for Tracheomalacia, Tracheopathia Osteoplastica, Tracheal Compression, and Staged Reconstruction of the Trachea").8 Fifteen patients were treated by membranous wall tracheoplasty for severe symptoms of expiratory airway collapse, including dyspnea (15), inability to clear secretions (5), and intractable cough (10), using polypropylene mesh (Marlex). Thirteen had symptomatic improvement and most had marked bronchoscopic improvement. Pulmonary function tests improved in some (Table 15-1), as did flow volume curves (Figure 15-5). One failure needed a stent. Three required late reoperation, one due to fluid collection beneath a prior Goretex splint, as noted. All improved with reoperation.8

Idiopathic tracheomalacia has been seen in a very small number of patients. Cartilages throughout the trachea, and sometimes in the main bronchi, become softened. Generalized floppiness is visualized broncho-scopically, rather than the specific deformation just described. The extent of disease usually obviates resection. The few patients I have seen were adult males with no known disease, except for diabetes in 2. No history of intubation or other tracheal insult explained the lesion. Patients presented with expiratory obstruction and a rubbery, resonating, "seal bark" cough. A few patients were treated by splinting the trachea externally with polypropylene rings placed in individual channels, which were then imbedded in the tracheal wall by turning down the sternohyoid muscles over them and suturing these to the trachea in the intervals between the plastic rings (see Chapter 32, "Surgery for Tracheomalacia, Tracheopathia Osteoplastica, Tracheal Compression, and Staged Reconstruction of the Trachea"). An alternative method of management is a long, large bore T or T-Y tube, as the anatomical defect requires, or an inlying stent, preferably of silicone.

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Responses

  • jesus
    What causes bronchial malacia in children?
    6 years ago
  • sarama mebrahtu
    Can you stent an upper trachea for malacia?
    18 days ago

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