A case of laryngotracheal stenosis masquerading as asthma.

Abstract: This report describes the case of a 21-year-old male that presented in respiratory failure caused by laryngotracheal stenosis (LTS) related to remote endotracheal intubation. The patient sought treatment for respiratory complaints in the weeks prior, and had a poor response to treatment for asthma. Currently. LTS is predominantly seen as a sequela of invasive airway management, and this case highlights the possibility of delayed presentations. Clinical manifestations and methods of diagnosis are described. Preventive measures, temporizing therapy, and definitive treatment are then discussed. With increasing numbers of patients undergoing invasive airway maneuvers, it is increasingly important for providers to recognize this disease. As is shown in this case, the diagnosis of LTS requires a high clinical suspicion in order to achieve a timely diagnosis and decrease morbidity and mortality.

**********

A 21-year-old African-American male presented with acute dyspnea and exercise intolerance that had been episodic over the preceding weeks. On examination, the patient was diaphoretic in respiratory distress with little air movement. The patient's family described several similar episodes occurring over the last few weeks requiring hospitalization. Each time, the patient was diagnosed and treated for asthma. The family also reported that the patient had been intubated four months ago for severe head trauma sustained in a motor vehicle collision.

The patient was started immediately on continuous nebulized albuterol, corticosteroids, and magnesium sulfate. Chest x-ray is shown in Figure 1. A blood gas on 100% oxygen revealed a pH of 7.146, a pC[O.sub.2] of 84, a p[O.sub.2] of 615, and bicarbonate of 28.4. The patient was orotracheally intubated via rapid sequence induction for impending respiratory failure. It was noted after intubation that the patient was difficult to ventilate via bag-valve-mask. Despite sedated mechanical ventilation with aggressive care, there was little improvement in respiratory status. Peak airway pressures remained in excess of 100 cm of water, with plateau pressures in the 30s.

On closer examination of the chest x-ray, narrowing of the tracheal air column was discerned. The diagnosis of laryngotracheal stenosis (LS) was entertained, and flexible bronchoscopy performed at the bedside revealed LTS with an intact airway diameter of 1 mm. Several unsuccessful attempts were made to cross the stenotic segment with an airway exchange catheter. The patient was then taken expeditiously to the operating room where a low tracheostomy was performed. Repeat bronchoscopy revealed severe stenosis extending from just above the carina to the level of the vocal cords (see Fig. 2). The patient was subsequently discharged several weeks later in good condition with a 6.5 endotracheal tube through a low tracheostomy.

Laryngotracheal stenosis is defined as anatomic narrowing of the upper airway, located anywhere from the supraglottic larynx to the distal trachea. Most causes of LTS in the early twentieth century were caused by trauma and infections, such as tuberculosis, syphilis, and diphtheria. Over the past 100 years, with the rise of critical care and invasive airway management. LTS as an iatrogenic sequelae of tracheal intubation has assumed greater importance. LTS may present in subtle ways: exercise intolerance, recurrent pneumonia, and chronic dyspnea. Early physician recognition of the patient with possible LTS is critical in decreasing morbidity and mortality.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

Discussion

Currently, LTS predominantly seen as a delayed sequela of invasive airway management. Other rare causes include amyloidosis, Wegener's granulomatosis, sarcoidosis, and idiopathic progressive subglottic stenosis. Couraud et al (1) described a large series of 217 patients with noncancerous stenosis of the upper airway from 1978 to 1992. In 201 patients (92%), stenosis was thought to be due to previous intubation.

The pathophysiologic sequence of events in postintubation LTS begins with excessive pressure exerted on the airway mucosal wall by the endotracheal tube. This pressure leads to impaired tracheal mucosal capillary perfusion, mucosal ischemia, tracheal chondritis, and, finally, fibrosis and progressive stenosis. Excessive endotracheal tube cuff pressures have clearly been shown to contribute to airway injury, and the use of conventional high volume, low pressure cuffs decreases the incidence of postintubation stenosis. (2,3,4) Larger than necessary endotracheal tubes, poor tube positioning, and excessive movement of the tube have also contributed to injury in one animal model. (5)

Duration of endotracheal intubation is also an important factor. In one study, the risk of LTS rose proportionally with a longer duration of intubation: a 2% incidence was noted in patients intubated for fewer than six days, a 5% incidence at 6 to 10 days, and a 12% incidence at greater than 11 days. (6) Early conversion to tracheostomy may prevent these complications. (7)

The clinical presentation of postintubation LTS is protean. Most cases are diagnosed immediately after extubation with acute respiratory insufficiency and stridor. However, delayed presentations are not uncommon. As in our case, there are several case reports of patients with LTS being mislabeled as adult-onset asthmatics and definitive diagnosis delayed. (8)

The signs and symptoms of LTS are nonspecific and depend on the location and degree of the stenosis. (9) Patients with stenosis of 50 to 60% present with persistent cough, progressive dyspnea on exertion, recurrent pneumonia, and exercise limitation. Patients with more severe stenosis present with inspiratory stridor and expiratory monophasic wheezing on exertion.

The diagnosis of postintubation LTS requires a high index of suspicion and an allowance should be made for delays in onset of symptoms. A stepwise approach to diagnosis is most effective beginning with plain films of the chest and neck. Helical CT delineates anatomy well, is noninvasive, and has reported sensitivity and specificity for LTS of 93% and 94% respectively. (10) Bronchoscopy may be effective both diagnostically and therapeutically.

Immediate treatment for acute respiratory insufficiency due to postintubation LTS hinges on the provision of a temporary airway. If possible, awake tracheal dilation under bronchoscopic guidance with a small endotracheal tube should be performed. This allows for temporary ventilation and oxygenation. If absolutely essential, percutaneous tracheostomy can be performed below the level of stenosis, sparing as much healthy trachea as possible.

The definitive treatment and prognosis of LTS depends on the location and severity of the stenosis. In general, tracheal lesions are more amenable to resection with end-to-end anastomosis, while laryngeal lesions are more amenable to laryngoplasty. (1) Limiting inflammation and re-operation is critical in preventing further scarring and ensuring the success of an anastomosis. (11)

For minor degrees of stenosis, bronchoscopic dilation, bronchoscopic resection, and stenting have been utilized. For more extensive lesions, segmental resection and primary anastomosis has been reported to be the most efficacious treatment with success rates greater than 90%. (12,13) A tension-free anastomosis is imperative to achieving success. A postoperative "chin stitch" may be placed that maintains the neck in flexion by suturing the mandibular symphyseal periosteum to the sternum. More invasive release maneuvers have been described to affect a tension-free repair: an infrahyoid muscle release, a suprahyoid muscle release, and the most invasive "hilar release." (14,15) The hilar release is performed through a thoracotomy, and consists of division of the pulmonary ligament with release and mobilization of the right lung hilum.

Conclusions

Symptomatic laryngotracheal stenosis related to previous tracheal intubation is a rare, but important, entity. Preventative measures in the critical care setting continue to be important in reducing the incidence of iatrogenic stenosis. With increasing numbers of patients undergoing invasive airway maneuvers, it is increasingly important for primary care providers to recognize the disease. As is shown in our case, the diagnosis of LTS requires a high clinical suspicion to achieve a timely diagnosis and decrease morbidity and mortality.

References

1. Couraud L, Jougon JB, Velly JF. Surgical treatment of nontumoral stenoses of the upper airway. Ann Thorac Surg 1995;60:250-260.

2. Lewis FR Jr, Schiobohm RM, Thomas AN. Prevention of complications from prolonged tracheal intubation. Am J Surg 1978;135:452-457.

3. Nordin U, Lindholom CE, Wolgast M. Blood flow in the rabbit tracheal mucosa under normal conditions and under the influence of tracheal intubation. Acta Anaesthesiol Scand 1977;21:81-94.

4. Grillo H, Cooper JD, Geffin B, et al. A low-pressure cuff for tracheostomy tubes to minimize tracheal injury. A comparative clinical trial. J Thorac Cardiovasc Surg 1971;62:898-907.

5. Whited RE. A study of endotracheal tube injury to the subglottis. Laryngoscope 1985;95:1216-1219.

6. Stauffer JL. Olson DE, Petty TL. Complications and consequences of endotracheal intubation and tracheotomy. A prospective study of 150 critically ill adult patients. Am J Med 1981;70:65-76.

7. Whited RE. A prospective study of laryngotracheal sequelae in long-term intubation. Laryngoscope 1984;94:367-377.

8. Nagappan R, Parkin G. Wright CA, et al. Adult long-segment tracheal stenosis attributable to complete tracheal rings masquerading as asthma. Crit Care Med 2002;30:238-240.

9. Sue RD, Susanto I. Long-term complications of artificial airways. Clin Chest Med 2003;24:457-471.

10. Whyte RI, Quint LE, Kazerooni EA, et al. Helical computed tomography for the evaluation of tracheal stenosis. Ann Thorac Surg 1995;60:27-30.

11. Wright C, Grillo H. Wain J, et al. Anastomotic complications after tracheal resection: prognostic factors and management. J Thorac Cardiovasc Surg 2004 Nov;128:731-739.

12. Grillo HC, Donahue DM. Post intubation tracheal stenosis. Semin Thorac Cardiovasc Surg 1996;8:370-380.

13. Har-El G, Shasha A, Chaudry R, et al. Resection of tracheal stenosis with end-to-end anastomosis. Ann Otol Rhinol Laryngol 1993;102:670-674.

14. Dedo HH, Fishman NH. Laryngeal release and sleeve resection for tracheal stenosis. Ann Otol Rhinol Laryngol 1969;78:285-288.

15. Montgomery WW. Suprahyoid release for tracheal anastomosis. Arch Otolaryngol 1974;99:255-260.

The cure for boredom is curiosity. There is no cure for curiosity.
--Dorothy Parker

Michael H. Catenacci, MD

From the Louisiana State University School of Medicine, New Orleans, LA.

Reprint requests to Michael H. Catenacci, MD, JTN 266, 619 19th Street South, Birmingham, AL. Email: [e-mail]

Accepted February 6, 2006.

RELATED ARTICLE: Key Points

* Laryngotracheal stenosis (LTS) is usually found in patients with a history of endotracheal intubation.

* LTS may not be immediately apparent in the post-intubation period; an allowance should be made for delay in onset of symptoms.

* A stepwise approach to diagnosis includes plain films, helical CT scanning, and bronchoscopy.

* Immediate treatment hinges on the provision of a temporary airway, while definitive treatment depends on the anatomic site and extent of stenosis.

* Providers need to be cognizant of this entity and maintain a high clinical suspicion in any patient that has undergone invasive airway management.