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Laryngomalacia, Tracheomalacia and Bronchomalacia
’
Laryngomalacia, Tracheomalacia and Bronchomalacia Erik B. Hysinger, MD, MS
Airway malacia can occur in the larynx (larygomalacia), trachea (tracheomalacia), or bronchi (bronchomalacia). As a group these are the most common congenital abnormalities of the pediatric airway and are characterized by increased airway compliance, resulting in excessive dynamic collapse during the respiratory cycle. While a diagnosis can be suspected based on clinical history and physical examination,
definitive evaluation is based of nasopharyngolaryngoscopy and/or bronchoscopy. Observation and conservative management are typically all that are required. However, surgical intervention can be necessary in the most severe cases, and can result in significant improvement in symptoms. Curr Probl Pediatr Adolesc Health Care ]]]];]:1-6
Dynamic Airway Collapse
The precise etiology of laryngomalacia is not well understood. Historically, abnormalities of the laryngeal alacia refers to an excessive softness of a structures and cartilage have been postulated to cause tissue, most often a bone or cartilage. In the laryngomalacia. Indeed, some patients with severe case of the airway, malacia refers to increased disease have a shortened aryepiglottic fold to glottic compliance of the conducting length ratio; however, similar airways. Airway malacia can decreased ratios can be seen in Malacia is the most common occur at the level of the larynx patients without laryngomalacongenital abnormality of the cia. Histologic specimens of (laryngomalacia), trachea (tracheomalacia), bronchi (broncholaryngeal cartilage demonstrate pediatric airway. malacia), or permutations of all mucosal edema and dilation of three. the lymphatic vessels, but no chondropathy.4 More recent research has identified abnormalities in sensorLaryngomalacia imotor integration in children with laryngomalacia.5,6 While laryngomalacia has been associated with Epidemiology neurologic, genetic, and cardiac disorders, gastroesoLaryngomalacia is the most common congenital phageal reflux disease is the most common comorbidanomaly of the larynx and accounts for more than ity.7 Theoretically, breathing 60% of the cases of stridor in against and obstructed airway pediatric patients.1,2 Supraglottic structures collapse into the larynx Intervention is only required in causes worsening reflux and laryngeal edema, which exacduring inspiration and result in the most severe cases. erbates airway obstruction, impendence to airflow. The larcreating a cyclical process ynx may be obstructed by prolapse of the aryepiglottic and worsening clinical symptoms. folds medially; the arytenoid, corniculate, or cuneiform
M
cartilage anteriorly; the epiglottis posteriorly; or a combination of the three (Fig. 1A and D).3
From the Division of Pulmonary Medicine, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH. Curr Probl Pediatr Adolesc Health Care ]]]];]:]]]-]]] 1538-5442/$ - see front matter & 2018 Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.cppeds.2018.03.002
Curr Probl PediatrAdolesc Health Care, ] ]]]]
Signs and Symptoms Positional stridor is present in the majority of infants with laryngomalacia, though it may not be the primary reason for presentation.8,9 Other respiratory symptoms such as accessory muscle use, respiratory distress, and hypoxemia can also occur, but are more common in severe cases. Patients with severe disease are also at increased risk for obstructive sleep apnea. Patients may also develop non-respiratory symptoms, especially in
1
severe disease. Feeding difficulty and dysphagia are frequently seen, and the combination of inadequate intake from impaired feeding and increased metabolic demand from respiratory distress can lead to failure to thrive.8,9 Symptoms usually begin within the first several days of life, but children may not present to medical attention until several months of age.8 Respiratory symptoms are typically worse in the supine position or during periods of increased respiratory effort such as crying or feeding. While symptoms can get worse over the first several months of life, patients typically have resolution by two years of age and often earlier.2,8
position with spontaneous respiration is more sensitive and specific for establishing the diagnosis.13
Treatment
Laryngomalacia typically has a benign course and resolves without interventions. Observation and/or conservative treatments with positioning and feeding therapy are sufficient in ~90% of patients.8 In patients with severe respiratory symptoms or failure to thrive, surgical intervention may be necessary.14 Supraglottoplasty is the most commonly performed surgical intervention and is successful for symptomatic relief and improved weight gain in most patients.15 In Diagnosis patients with posterior collapse of the epiglottis, Laryngomalacia can be suspected based on the epiglottopexy can be used to ameliorate symptoms.16 classic findings of positional If endoscopic surgery is unsucinspiratory stridor. However, cessful, tracheostomy is an other pathology can be indistinalternative treatment for refracDefinitive diagnosis require guishable from laryngomalacia tory disease.17 direct airway visualization. based solely on clinical history and physical examination,10 and Tracheomalacia radiographic techniques demonstrate poor accuracy in Epidemiology identifying disease.11 Thus, direct visualization with nasopharyngolaryngoscopy (NPL) is the gold standard Tracheomalacia is characterized by an increased for the diagnosis of laryngomalacia. NPL can be compliance of the intra or extrathoracic trachea resultperformed in an awake patient seated upright in a ing in dynamic collapse during the respiratory cycle parent’s arms12; however, sedated NPL in the supine (Fig. 1B and E). Congenital tracheomalacia results
A
C
E
B
D
F
Inhalaon
Exhalaon
Figure 1. Endoscopic view of the larynx during inhalation with anterior prolapse of the arytenoid cartilage in a patient with laryngomalacia (A) and during exhalation (B). Endoscopic view of the distal trachea during inhalation(C) and during exhalation with partial collapse of the tracheal lumen in a patient with tracheomalacia (D). Endoscopic view of the left main bronchus during inhalation (E) and during exhalation (F) with nearly complete occlusion of the lumen in a patient with bronchomalacia.
2
Curr Probl Pediatr Adolesc Health Care, ] ]]]]
from abnormal development of the tracheal cartilage and smooth muscle and occurs in about 1:2100 children.18 Congenital tracheomalacia may occur in isolation but has also been associated with other airway abnormalities such as tracheoesophageal fistulas, laryngeal clefts, laryngomalacia, and bronchomalacia.19 Acquired tracheomalacia occurs in the normally developed trachea that undergoes damage from external compression, trauma, positive pressure ventilation, infection, or inflammation. Tracheomalacia related to external compression from a vascular ring was first described in the 1930s.20 In children, vascular abnormalities or congenital heart defects are the most common reason for compression of the trachea. However, the integrity of the tracheal wall can also be jeopardized by the axial skeleton as seen in severe scoliosis or pectus excavatum and space occupying lesions such as tumors, cysts, infections, and goiter.21 Trauma to the tracheal cartilage from tracheostomy is perhaps the post common cause of acquired tracheomalacia. Increased tracheal compliance may be present just proximal to the stoma, or more distally due to mechanical irritation and inflammation from the tracheostomy tube or cuff.22 Patients with tracheostomy tubes are frequently exposed to positive pressure ventilation, which can further damage the airway by causing over distention, decreased thickness of the cartilage and smooth muscle, and epithelial necrosis and inflammation.23 Premature infants are also often exposed to prolonged periods of positive pressure ventilation. The combination of immature airways, which are particularly susceptible to airway deformation, and exposure to positive pressure appears to cause a high prevalence of disease in this population as well.24
Signs and Symptoms Children with tracheomalacia have impaired ability to clear airway secretions and can develop recurrent bacterial bronchitis or pneumonia. Excessive dynamic collapse can also cause cyanotic spells, apnea, and difficulty weaning ventilator support.18,25,26 In extrathoracic tracheomalacia, dynamic collapse occurs during inspiration. As a result, these patients can present with stridor, prolong inspiratory phase, low lung volumes, and dyspnea on exertion. In intrathoracic tracheomalacia, dynamic collapse occurs during exhalation, and patients can present with barking cough, diffuse monophonic wheeze, and prolonged expiratory phase.26 Curr Probl PediatrAdolesc Health Care, ] ]]]]
Diagnostic Evaluation Although tracheomalacia is one of the most common abnormalities of the conducting airway, there is no current standardized set of diagnostic criteria. Tracheomalacia may be suspected based on signs and symptoms as well as reduction in peak expiratory flow on pulmonary function testing; however, diagnosis of tracheomalacia based on clinical suspicion and pulmonary function is neither sensitive nor specific.18 Because clinical diagnosis is often not reliable, radiographic techniques are commonly used to establish the diagnosis of tracheomalacia. Two-dimensional radiographic techniques such as tracheograms and airway fluoroscopy only measure the change in anterior–posterior diameter of the airway during the respiratory cycle and are specific but poorly sensitive for diagnosing tracheomalacia.27 However, threedimensional radiography with dynamic multi-detector computed tomography (MDCT) permits evaluation of the cross-sectional area of the trachea, and can be highly accurate in identifying tracheomalacia in highrisk pediatric patients; however, dynamic MDCT exposes children to ionizing radiation and may require intubation and general anesthesia, which can mask dynamic collapse.28,29 Despite the advances in dynamic MDCT, bronchoscopy remains the gold standard for the diagnosis of tracheomalacia. Flexible bronchoscopy is the preferred modality as it permits spontaneous breathing and real-time, direct visualization and dynamic assessment of the trachea during spontaneous respiration. Flexible bronchoscopy performed via a trans-nasal approach also minimizes the distortion of the airway that can occur with intubation or rigid bronchoscopy.30 Most authors agree that 450% narrowing of the airway lumen is diagnostic of tracheomalacia21 and there is high intra and inter-rater reliability for the diagnosis using bronchoscopy.31
Treatment Tracheomalacia is often a self-limited disease and improves or resolves within the first two years of life.25 However, patients with severe or refractory symptoms may require medical treatment. Pharmacotherapies such as bethanechol and low-dose, inhaled ipratroprium can increase airway smooth muscle tone and improve respiratory mechanics in patients with tracheomalacia.32,33 Continuous positive airway pressure (CPAP) can also be used to treat
3
children with dynamic collapse of the trachea. While non-invasive CPAP provides distending pressure that prevents airway collapse on exhalation and raises lung volumes for greater expiratory flow, CPAP administered via tracheostomy or endotracheal tube can additionally bypass the collapsible segment of the airway.34,35 When medical management fails, surgical correction may be necessary to ameliorate symptoms of tracheomalacia. Currently, aortopexy is the mainstay of surgical correction in pediatrics. Aortopexy provides symptomatic relief in many patients, but the malacic segment persists after the procedure.36 Slide tracheoplasty is a surgical procedure that removes the malacic segment and has been posited as a method of treating patients with short segment tracheomalacia related to tracheoesophageal fistulas.37 In adult patients, silicone stents are frequently used as a minimally invasive method to maintain airway lumen patency and provide symptomatic relief.38 Although silicone stents are infrequently used in pediatrics due to problems inherent to the growing child, recent research has shown promise using biodegradable airway stents for children.39
Bronchomalacia Epidemiology Bronchomalacia is characterized by increased compliance of the bronchi with dynamic collapse during exhalation (Fig. 1C and F). Typically, bronchomalacia refers to the right and left main bronchi, though any bronchus can be affected. In some reports, bronchomalacia of the left main bronchus was more common, possibly due to the longer length when compared to the right main stem bronchus and the relationship with the pulmonary artery.19,40 However, others have found the right main-stem bronchus to be affected more often.41 The risk factors are similar to tracheomalacia and include tracheoesophageal fistulas, congenital heart disease, and prematurity. However, bronchomalacia can additionally be the result of complications of the anastomotic site following lung transplantation.42 There also appears to be an association of bronchomalacia and congenital hyperlucent lung, though it is unclear whether this relationship is causal or consequent.19
Signs and Symptoms The signs and symptoms are similar to intra-thoracic tracheomalacia. Patients can present with cough and
4
harsh, monophonic wheezing especially during viral illnesses; however, unlike tracheomalacia, wheezing is most often unilateral. Dynamic collapse of the bronchus can reduce peak expiratory flow during spirometry and impairs secretion clearance, which increases the risk of pneumonia and atelectasis.40
Diagnosis As with tracheomalacia, bronchoscopy remains the gold standard for the diagnosis of bronchomalacia. Bronchograms and airway fluoroscopy have been used to diagnose bronchomalacia, but the accuracy of these modalities has not been rigorously evaluated.43,44 The use of computed tomography has demonstrated variable accuracy in the diagnosis of bronchomalacia.29,45
Treatment Bronchomalacia does not typically require intervention39; however, patients with severe disease, respiratory distress, impaired gas exchange, or failure to thrive may require treatment. Therapeutic options closely resemble those of tracheomalacia. Inhaled ipratroprium can provide symptomatic relief but has not been systematically studied.40 Treatment with positive pressure ventilation can improve symptoms and respiratory and respiratory mechanics.44 When medical management is not successful, surgical correction with pulmonary artery pexy have also been used the treatment of bronchomalacia.46
References 1. Thorne MC, Garetz SL. Laryngomalacia: review and summary of current clinical practice in 2015. Paediatr Respir Rev 2015;17:3–8. 2. Holinger PH, Johnston KC, Schiller F. Congenital anomalies of the larynx. Trans Am Laryngol Assoc 1954;75:64–90. 3. van der Heijden M, Dikkers FG, Halmos GB. The groningen laryngomalacia classification system-based on systematic review and dynamic airway changes. Pediatr Pulmonol 2015;50(12):1368–73. 4. Chandra RK, Gerber ME, Holinger LD. Histological insight into the pathogenesis of severe laryngomalacia. Int J Pediatr Otorhinolaryngol 2001;61(1):31–8. 5. Munson PD, Saad AG, El-Jamal SM, Dai Y, Bower CM, Richter GT. Submucosal nerve hypertrophy in congenital laryngomalacia. Laryngoscope 2011;121(3):627–9. 6. Thompson DM. Abnormal sensorimotor integrative function of the larynx in congenital laryngomalacia: a new theory of etiology. Laryngoscope 2007;117(6):1–33. 7. Matthews BL, Little JP, McGuirt W.F. Jr., Koufman JA. Reflux in infants with laryngomalacia: results of 24-hour double-probe pH monitoring. Otolaryngol Head Neck Surg 1999;120(6):860–4.
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8. Wright CT, Goudy SL. Congenital laryngomalacia: symptom duration and need for surgical intervention. Ann Otol Rhinol Laryngol 2012;121(1):57–60. 9. Cooper T, Benoit M, Erickson B, El-Hakim H. Primary presentations of laryngomalacia. JAMA Otolaryngol Head Neck Surg 2014;140(6):521–6. 10. Zwartenkot JW, Hoeve HL, Borgstein J. Inter-observer reliability of localization of recorded stridor sounds in children. Int J Pediatr Otorhinolaryngol 2010;74(10):1184–8. 11. Huntley C, Carr MM. Evaluation of the effectiveness of airway fluoroscopy in diagnosing patients with laryngomalacia. Laryngoscope 2010;120(7):1430–4. 12. Lima TM, Goncalves DU, Goncalves LV, Reis PA, Lana AB, Guimaraes FF. Flexible nasolaryngoscopy accuracy in laryngomalacia diagnosis. Braz J Otorhinolaryngol 2008; 74(1):29–32. 13. Sivan Y, Ben-Ari J, Soferman R, DeRowe A. Diagnosis of laryngomalacia by fiberoptic endoscopy: awake compared with anesthesia-aided technique. Chest 2006;130(5):1412–8. 14. Roger G, Denoyelle F, Triglia JM, Garabedian EN. Severe laryngomalacia: surgical indications and results in 115 patients. Laryngoscope 1995;105(10):1111–7. 15. Czechowicz JA, Chang KW. Catch-up growth in infants with laryngomalacia after supraglottoplasty. Int J Pediatr Otorhinolaryngol 2015;79(8):1333–6. 16. Whymark AD, Clement WA, Kubba H, Geddes NK. Laser epiglottopexy for laryngomalacia: 10 years’ experience in the west of Scotland. Arch Otolaryngol Head Neck Surg 2006;132 (9):978–82. 17. Richter GT, Thompson DM. The surgical management of laryngomalacia. Otolaryngol Clin North Am 2008;41 (5):837–64:vii. 18. Boogaard R, Huijsmans SH, Pijnenburg MW, Tiddens HA, de Jongste JC, Merkus PJ. Tracheomalacia and bronchomalacia in children: incidence and patient characteristics. Chest 2005; 128(5):3391–7. 19. Masters IB, Chang AB, Patterson L, et al. Series of laryngomalacia, tracheomalacia, and bronchomalacia disorders and their associations with other conditions in children. Pediatr Pulmonol 2002;34(3):189–95. 20. Sprague HB, Ernlund CH, Albright F. Clinical aspects of persistent right aortic root. Trans Am Clin Climatol Assoc 1933;49:83–94. 21. Carden KA, Boiselle PM, Waltz DA, Ernst A. Tracheomalacia and tracheobronchomalacia in children and adults: an in-depth review. Chest 2005;127(3):984–1005. 22. Feist JH, Johnson TH, Wilson RJ. Acquired tracheomalacia: etiology and differential diagnosis. Chest 1975;68(3):340–5. 23. Deoras KS, Wolfson MR, Bhutani VK, Shaffer TH. Structural changes in the tracheae of preterm lambs induced by ventilation. Pediatr Res 1989;26(5):434–7. 24. Downing GJ, Kilbride HW. Evaluation of airway complications in high-risk preterm infants: application of flexible fiberoptic airway endoscopy. Pediatrics 1995;95(4):567–72. 25. Pan W, Peng D, Luo J, et al. Clinical features of airway malacia in children: a retrospective analysis of 459 patients. Int J Clin Exp Med 2014;7(9):3005–12.
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26. Wittenborg MH, Gyepes MT, Crocker D. Tracheal dynamics in infants with respiratory distress, stridor, and collapsing trachea. Radiology 1967;88(4):653–62. 27. Sanchez MO, Greer MC, Masters IB, Chang AB. A comparison of fluoroscopic airway screening with flexible bronchoscopy for diagnosing tracheomalacia. Pediatr Pulmonol 2012;47(1):63–7. 28. Lee EY, Zurakowski D, Waltz DA, et al. MDCT evaluation of the prevalence of tracheomalacia in children with mediastinal aortic vascular anomalies. J Thorac Imaging 2008;23(2):258–65. 29. Ngerncham M, Lee EY, Zurakowski D, Tracy DA, Jennings R. Tracheobronchomalacia in pediatric patients with esophageal atresia: comparison of diagnostic laryngoscopy/bronchoscopy and dynamic airway multidetector computed tomography. J Pediatr Surg 2015;50(3):402–7. 30. Wood RE. Evaluation of the upper airway in children. Curr Opin Pediatr 2008;20(3):266–71. 31. Majid A, Gaurav K, Sanchez JM, et al. Evaluation of tracheobronchomalacia by dynamic flexible bronchoscopy. A pilot study. Ann Am Thorac Soc 2014;11(6):951–5. 32. Patel HJ, Barnes PJ, Takahashi T, Tadjkarimi S, Yacoub MH, Belvisi MG. Evidence for prejunctional muscarinic autoreceptors in human and guinea pig trachea. Am J Respir Crit Care Med 1995;152(3):872–8. 33. Panitch HB, Keklikian EN, Motley RA, Wolfson MR, Schidlow DV. Effect of altering smooth muscle tone on maximal expiratory flows in patients with tracheomalacia. Pediatr Pulmonol 1990;9:170–6. 34. Panitch HB, Allen JL, Alpert BE, Schidlow DV. Effects of CPAP on lung mechanics in infants with acquired tracheobronchomalacia. Am J Respir Crit Care Med 1994;150(5): 1341–6. 35. Davis S, Jones M, Kisling J, Angelicchio C, Tepper RS. Effect of continuous positive airway pressure on forced expiratory flows in infants with tracheomalacia. Am J Respir Crit Care Med 1998;158(1):148–52. 36. Dave S, Currie BG. The role of aortopexy in severe tracheomalacia. J Pediatr Surg 2006;41(3):533–7. 37. Provenzano MJ, Rutter MJ, von Allmen D, et al. Slide tracheoplasty for the treatment of tracheoesophogeal fistulas. J Pediatr Surg 2014;49(6):910–4. 38. Ernst A, Majid A, Feller-Kopman D, et al. Airway stabilization with silicone stents for treating adult tracheobronchomalacia: a prospective observational study. Chest 2007;132(2): 609–616. 39. Vondrys D, Elliott MJ, McLaren CA, Noctor C, Roebuck DJ. First experience with biodegradable airway stents in children. Ann Thorac Surg 2011;92(5):1870–4. 40. Finder JD. Primary bronchomalacia in infants and children. J Pediatr 1997;130(1):59–66. 41. Yalcin E, Dogru D, Ozcelik U, Kiper N, Aslan AT, Gozacan A. Tracheomalacia and bronchomalacia in 34 children: clinical and radiologic profiles and associations with other diseases. Clin Pediatr (Phila) 2005;44(9):777–81. 42. Lopez-Padilla D, Garcia-Lujan R, de Pablo A, de Miguel Poch E. Oki stenting for anastomotic bronchomalacia in lung transplantation. Eur J Cardiothorac Surg 2015;48(3):e53–4.
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43. Doull IJ, Mok Q, Tasker RC. Tracheobronchomalacia in preterm infants with chronic lung disease. Arch Dis Child Fetal Neonatal Ed 1997;76(3):F203–5. 44. Austin J, Ali T. Tracheomalacia and bronchomalacia in children: pathophysiology, assessment, treatment and anaesthesia management. Paediatr Anaesth 2003;13(1):3–11.
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45. Lee S, Im SA, Yoon JS. Tracheobronchomalacia in infants: the use of non-breath held 3D CT bronchoscopy. Pediatr Pulmonol 2014;49(10):1028–35. 46. Kamata S, Usui N, Sawai T, et al. Pexis of the great vessels for patients with tracheobronchomalacia in infancy. J Pediatr Surg 2000;35(3):454–7.
Curr Probl Pediatr Adolesc Health Care, ] ]]]]
Laryngomalacia, Tracheomalacia and Bronchomalacia Erik B. Hysinger, MD, MS
Airway malacia can occur in the larynx (larygomalacia), trachea (tracheomalacia), or bronchi (bronchomalacia). As a group these are the most common congenital abnormalities of the pediatric airway and are characterized by increased airway compliance, resulting in excessive dynamic collapse during the respiratory cycle. While a diagnosis can be suspected based on clinical history and physical examination,
definitive evaluation is based of nasopharyngolaryngoscopy and/or bronchoscopy. Observation and conservative management are typically all that are required. However, surgical intervention can be necessary in the most severe cases, and can result in significant improvement in symptoms. Curr Probl Pediatr Adolesc Health Care ]]]];]:1-6
Dynamic Airway Collapse
The precise etiology of laryngomalacia is not well understood. Historically, abnormalities of the laryngeal alacia refers to an excessive softness of a structures and cartilage have been postulated to cause tissue, most often a bone or cartilage. In the laryngomalacia. Indeed, some patients with severe case of the airway, malacia refers to increased disease have a shortened aryepiglottic fold to glottic compliance of the conducting length ratio; however, similar airways. Airway malacia can decreased ratios can be seen in Malacia is the most common occur at the level of the larynx patients without laryngomalacongenital abnormality of the cia. Histologic specimens of (laryngomalacia), trachea (tracheomalacia), bronchi (broncholaryngeal cartilage demonstrate pediatric airway. malacia), or permutations of all mucosal edema and dilation of three. the lymphatic vessels, but no chondropathy.4 More recent research has identified abnormalities in sensorLaryngomalacia imotor integration in children with laryngomalacia.5,6 While laryngomalacia has been associated with Epidemiology neurologic, genetic, and cardiac disorders, gastroesoLaryngomalacia is the most common congenital phageal reflux disease is the most common comorbidanomaly of the larynx and accounts for more than ity.7 Theoretically, breathing 60% of the cases of stridor in against and obstructed airway pediatric patients.1,2 Supraglottic structures collapse into the larynx Intervention is only required in causes worsening reflux and laryngeal edema, which exacduring inspiration and result in the most severe cases. erbates airway obstruction, impendence to airflow. The larcreating a cyclical process ynx may be obstructed by prolapse of the aryepiglottic and worsening clinical symptoms. folds medially; the arytenoid, corniculate, or cuneiform
M
cartilage anteriorly; the epiglottis posteriorly; or a combination of the three (Fig. 1A and D).3
From the Division of Pulmonary Medicine, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH. Curr Probl Pediatr Adolesc Health Care ]]]];]:]]]-]]] 1538-5442/$ - see front matter & 2018 Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.cppeds.2018.03.002
Curr Probl PediatrAdolesc Health Care, ] ]]]]
Signs and Symptoms Positional stridor is present in the majority of infants with laryngomalacia, though it may not be the primary reason for presentation.8,9 Other respiratory symptoms such as accessory muscle use, respiratory distress, and hypoxemia can also occur, but are more common in severe cases. Patients with severe disease are also at increased risk for obstructive sleep apnea. Patients may also develop non-respiratory symptoms, especially in
1
severe disease. Feeding difficulty and dysphagia are frequently seen, and the combination of inadequate intake from impaired feeding and increased metabolic demand from respiratory distress can lead to failure to thrive.8,9 Symptoms usually begin within the first several days of life, but children may not present to medical attention until several months of age.8 Respiratory symptoms are typically worse in the supine position or during periods of increased respiratory effort such as crying or feeding. While symptoms can get worse over the first several months of life, patients typically have resolution by two years of age and often earlier.2,8
position with spontaneous respiration is more sensitive and specific for establishing the diagnosis.13
Treatment
Laryngomalacia typically has a benign course and resolves without interventions. Observation and/or conservative treatments with positioning and feeding therapy are sufficient in ~90% of patients.8 In patients with severe respiratory symptoms or failure to thrive, surgical intervention may be necessary.14 Supraglottoplasty is the most commonly performed surgical intervention and is successful for symptomatic relief and improved weight gain in most patients.15 In Diagnosis patients with posterior collapse of the epiglottis, Laryngomalacia can be suspected based on the epiglottopexy can be used to ameliorate symptoms.16 classic findings of positional If endoscopic surgery is unsucinspiratory stridor. However, cessful, tracheostomy is an other pathology can be indistinalternative treatment for refracDefinitive diagnosis require guishable from laryngomalacia tory disease.17 direct airway visualization. based solely on clinical history and physical examination,10 and Tracheomalacia radiographic techniques demonstrate poor accuracy in Epidemiology identifying disease.11 Thus, direct visualization with nasopharyngolaryngoscopy (NPL) is the gold standard Tracheomalacia is characterized by an increased for the diagnosis of laryngomalacia. NPL can be compliance of the intra or extrathoracic trachea resultperformed in an awake patient seated upright in a ing in dynamic collapse during the respiratory cycle parent’s arms12; however, sedated NPL in the supine (Fig. 1B and E). Congenital tracheomalacia results
A
C
E
B
D
F
Inhalaon
Exhalaon
Figure 1. Endoscopic view of the larynx during inhalation with anterior prolapse of the arytenoid cartilage in a patient with laryngomalacia (A) and during exhalation (B). Endoscopic view of the distal trachea during inhalation(C) and during exhalation with partial collapse of the tracheal lumen in a patient with tracheomalacia (D). Endoscopic view of the left main bronchus during inhalation (E) and during exhalation (F) with nearly complete occlusion of the lumen in a patient with bronchomalacia.
2
Curr Probl Pediatr Adolesc Health Care, ] ]]]]
from abnormal development of the tracheal cartilage and smooth muscle and occurs in about 1:2100 children.18 Congenital tracheomalacia may occur in isolation but has also been associated with other airway abnormalities such as tracheoesophageal fistulas, laryngeal clefts, laryngomalacia, and bronchomalacia.19 Acquired tracheomalacia occurs in the normally developed trachea that undergoes damage from external compression, trauma, positive pressure ventilation, infection, or inflammation. Tracheomalacia related to external compression from a vascular ring was first described in the 1930s.20 In children, vascular abnormalities or congenital heart defects are the most common reason for compression of the trachea. However, the integrity of the tracheal wall can also be jeopardized by the axial skeleton as seen in severe scoliosis or pectus excavatum and space occupying lesions such as tumors, cysts, infections, and goiter.21 Trauma to the tracheal cartilage from tracheostomy is perhaps the post common cause of acquired tracheomalacia. Increased tracheal compliance may be present just proximal to the stoma, or more distally due to mechanical irritation and inflammation from the tracheostomy tube or cuff.22 Patients with tracheostomy tubes are frequently exposed to positive pressure ventilation, which can further damage the airway by causing over distention, decreased thickness of the cartilage and smooth muscle, and epithelial necrosis and inflammation.23 Premature infants are also often exposed to prolonged periods of positive pressure ventilation. The combination of immature airways, which are particularly susceptible to airway deformation, and exposure to positive pressure appears to cause a high prevalence of disease in this population as well.24
Signs and Symptoms Children with tracheomalacia have impaired ability to clear airway secretions and can develop recurrent bacterial bronchitis or pneumonia. Excessive dynamic collapse can also cause cyanotic spells, apnea, and difficulty weaning ventilator support.18,25,26 In extrathoracic tracheomalacia, dynamic collapse occurs during inspiration. As a result, these patients can present with stridor, prolong inspiratory phase, low lung volumes, and dyspnea on exertion. In intrathoracic tracheomalacia, dynamic collapse occurs during exhalation, and patients can present with barking cough, diffuse monophonic wheeze, and prolonged expiratory phase.26 Curr Probl PediatrAdolesc Health Care, ] ]]]]
Diagnostic Evaluation Although tracheomalacia is one of the most common abnormalities of the conducting airway, there is no current standardized set of diagnostic criteria. Tracheomalacia may be suspected based on signs and symptoms as well as reduction in peak expiratory flow on pulmonary function testing; however, diagnosis of tracheomalacia based on clinical suspicion and pulmonary function is neither sensitive nor specific.18 Because clinical diagnosis is often not reliable, radiographic techniques are commonly used to establish the diagnosis of tracheomalacia. Two-dimensional radiographic techniques such as tracheograms and airway fluoroscopy only measure the change in anterior–posterior diameter of the airway during the respiratory cycle and are specific but poorly sensitive for diagnosing tracheomalacia.27 However, threedimensional radiography with dynamic multi-detector computed tomography (MDCT) permits evaluation of the cross-sectional area of the trachea, and can be highly accurate in identifying tracheomalacia in highrisk pediatric patients; however, dynamic MDCT exposes children to ionizing radiation and may require intubation and general anesthesia, which can mask dynamic collapse.28,29 Despite the advances in dynamic MDCT, bronchoscopy remains the gold standard for the diagnosis of tracheomalacia. Flexible bronchoscopy is the preferred modality as it permits spontaneous breathing and real-time, direct visualization and dynamic assessment of the trachea during spontaneous respiration. Flexible bronchoscopy performed via a trans-nasal approach also minimizes the distortion of the airway that can occur with intubation or rigid bronchoscopy.30 Most authors agree that 450% narrowing of the airway lumen is diagnostic of tracheomalacia21 and there is high intra and inter-rater reliability for the diagnosis using bronchoscopy.31
Treatment Tracheomalacia is often a self-limited disease and improves or resolves within the first two years of life.25 However, patients with severe or refractory symptoms may require medical treatment. Pharmacotherapies such as bethanechol and low-dose, inhaled ipratroprium can increase airway smooth muscle tone and improve respiratory mechanics in patients with tracheomalacia.32,33 Continuous positive airway pressure (CPAP) can also be used to treat
3
children with dynamic collapse of the trachea. While non-invasive CPAP provides distending pressure that prevents airway collapse on exhalation and raises lung volumes for greater expiratory flow, CPAP administered via tracheostomy or endotracheal tube can additionally bypass the collapsible segment of the airway.34,35 When medical management fails, surgical correction may be necessary to ameliorate symptoms of tracheomalacia. Currently, aortopexy is the mainstay of surgical correction in pediatrics. Aortopexy provides symptomatic relief in many patients, but the malacic segment persists after the procedure.36 Slide tracheoplasty is a surgical procedure that removes the malacic segment and has been posited as a method of treating patients with short segment tracheomalacia related to tracheoesophageal fistulas.37 In adult patients, silicone stents are frequently used as a minimally invasive method to maintain airway lumen patency and provide symptomatic relief.38 Although silicone stents are infrequently used in pediatrics due to problems inherent to the growing child, recent research has shown promise using biodegradable airway stents for children.39
Bronchomalacia Epidemiology Bronchomalacia is characterized by increased compliance of the bronchi with dynamic collapse during exhalation (Fig. 1C and F). Typically, bronchomalacia refers to the right and left main bronchi, though any bronchus can be affected. In some reports, bronchomalacia of the left main bronchus was more common, possibly due to the longer length when compared to the right main stem bronchus and the relationship with the pulmonary artery.19,40 However, others have found the right main-stem bronchus to be affected more often.41 The risk factors are similar to tracheomalacia and include tracheoesophageal fistulas, congenital heart disease, and prematurity. However, bronchomalacia can additionally be the result of complications of the anastomotic site following lung transplantation.42 There also appears to be an association of bronchomalacia and congenital hyperlucent lung, though it is unclear whether this relationship is causal or consequent.19
Signs and Symptoms The signs and symptoms are similar to intra-thoracic tracheomalacia. Patients can present with cough and
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harsh, monophonic wheezing especially during viral illnesses; however, unlike tracheomalacia, wheezing is most often unilateral. Dynamic collapse of the bronchus can reduce peak expiratory flow during spirometry and impairs secretion clearance, which increases the risk of pneumonia and atelectasis.40
Diagnosis As with tracheomalacia, bronchoscopy remains the gold standard for the diagnosis of bronchomalacia. Bronchograms and airway fluoroscopy have been used to diagnose bronchomalacia, but the accuracy of these modalities has not been rigorously evaluated.43,44 The use of computed tomography has demonstrated variable accuracy in the diagnosis of bronchomalacia.29,45
Treatment Bronchomalacia does not typically require intervention39; however, patients with severe disease, respiratory distress, impaired gas exchange, or failure to thrive may require treatment. Therapeutic options closely resemble those of tracheomalacia. Inhaled ipratroprium can provide symptomatic relief but has not been systematically studied.40 Treatment with positive pressure ventilation can improve symptoms and respiratory and respiratory mechanics.44 When medical management is not successful, surgical correction with pulmonary artery pexy have also been used the treatment of bronchomalacia.46
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