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* From the Departments of Radiology (Drs. Kim, Shin, Song, Ko, Yoon, and Sung) and Internal Medicine (Dr. Shim), Division of Pulmonology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
Correspondence to: Ji Hoon Shin, MD, Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388–1, Pungnap-2dong, Songpa-gu, Seoul 138–736, Korea; e-mail: jhshin{at}amc.seoul.kr
Abstract
Background: Although balloon dilation is a safe procedure, it can lead to laceration of the airway, causing bleeding, pneumothorax, pneumomediastinum, or mediastinitis. We therefore determined the incidence and clinical significance of tracheobronchial lacerations after balloon dilation for treatment of benign tracheobronchial strictures.
Methods: We evaluated 97 patients who had undergone balloon dilation in 124 sessions for the treatment of benign tracheobronchial strictures. The degree of airway laceration was evaluated bronchoscopically. The cumulative airway patency rate after balloon dilation was compared in patients with and without lacerations using Kaplan-Meier survival curves and log-rank testing.
Results: There were 64 tracheobronchial lacerations (51.6%) during the 124 sessions of balloon dilation. Of these, 60 were superficial and 4 were deep, but there were no incidents of transmural laceration. In patients with lacerations, mild chest pain (n = 5), blood-tinged sputum (n = 21), and pneumomediastinum (n = 2) occurred, but all resolved completely within 24 h. All superficial lacerations healed spontaneously within 1 month, and all deep lacerations healed 2 to 9 months after conservative treatment. During the follow-up period, the median cumulative airway patency period in patients with and without lacerations was 24 and 4 months (p < 0.05), respectively.
Conclusion: Laceration secondary to balloon dilation in the tracheobronchial tree is relatively common but rarely progresses to transmural laceration and may improve patency outcomes.
Key Words: airway • airway strictures • balloon dilation • bronchoscopy • trauma
Endoscopically or fluoroscopically guided balloon dilation has become an accepted treatment for benign tracheobronchial strictures, primarily because balloon dilation is associated with lower morbidity and mortality rates compared with corrective surgery or bougienage.123456 Although balloon dilation is a safe and effective procedure, balloon inflation can lead to laceration of the airway, causing bleeding, pneumothorax, pneumomediastinum, or mediastinitis. Although one case of free rupture of the tracheobronchial tree after balloon dilation requiring surgical management has been reported,7 as well as two cases of spontaneous healing of deep tracheal lacerations at 2 and 8 months after balloon dilation,8 the true incidence and clinical significance of tracheobronchial lacerations after balloon dilation are still not known. In our experience, tracheobronchial lacerations frequently resulted from balloon dilation for benign tracheobronchial strictures. We have therefore determined the incidence and clinical significance of tracheobronchial lacerations after balloon dilation for benign tracheobronchial strictures.
Materials and Methods
The study protocol was approved by our institutional review board, and all patients provided written informed consent at the time of study enrollment.
Patients
We retrospectively reviewed the records and/or images of patients who underwent balloon dilation for benign tracheobronchial strictures. We excluded patients with multiple strictures (n = 4), those without follow-up bronchoscopy after balloon dilation (n = 2), and those in whom the procedure failed (n = 1). From January 1998 to May 2006, 97 patients (70 women and 27 men; age range, 10 to 82 years; mean age, 42 years) underwent balloon dilation in 124 sessions for the treatment of benign tracheobronchial strictures caused by endobronchial tuberculosis (n = 72), posttracheostomy/postintubation stricture (n = 12), or postoperative anastomotic stricture (n = 13). The stenotic sites were the trachea (n = 22), the main bronchus (right, n = 12; left, n = 55), and the lobar bronchus (n = 8).
Balloon Dilation and Follow-up
The pharynx and larynx were topically anesthetized with an aerosol spray, the patients were sedated, and their oxygen saturation was monitored throughout the procedure. A 0.035-inch angled exchange guidewire (Terumo; Tokyo, Japan) was inserted through the bronchoscopic channel and positioned across the stenosis. After removal of the bronchoscope, an angioplasty balloon catheter (Boston Scientific/Medi-tech; Watertown, MA; and Cordis; Roden, the Netherlands) was passed over the guidewire under fluoroscopic guidance, correctly positioned across the stenosis, and inflated with diluted water-soluble contrast medium at inflation pressures as high as 16 atm (as established by a pressure-gauge monitor). In children, 6-mm-diameter balloon catheters were used in the bronchi and trachea, whereas, in adults, 10-mm to 12-mm-diameter balloon catheters were used in the bronchi and 14-mm to 20-mm-diameter balloon catheters were used in the trachea. The diameter of the balloon was chosen to be closest to that of the lumen measured at the proximal region of the normal bronchus. During each session, two to three serial balloon inflations were performed for 60 to 180 s, until the balloon waist formed by the airway stenosis disappeared or until the patient could not tolerate further inflation. A session was defined as any procedure performed on a single day.
Bronchoscopy was performed by one bronchoscopist consistently in all patients just before and after balloon dilation to evaluate the degree of dilation of the stenotic segment and the degree of laceration of the trachea and/or bronchi. If a laceration was detected immediately after balloon dilation, bronchoscopy was performed every 2 weeks until the laceration healed. Follow-up bronchoscopy was also performed if recurrent stenosis was suspected.
Definition and Analysis of Data
The degree of laceration was classified as superficial (depth, 
2 mm), deep (depth, > 2 mm), or as transmural if the injury extended through all layers of the airway wall. The study population was divided into the following two groups: patients with tracheal or bronchial lacerations (group A); and patients without tracheal or bronchial lacerations (group B). Age, sex, cause and site of stenosis, and diameter and length of stenosis were compared between the two groups. Continuous variables were compared using the Student t test, and categorical variables were compared using the 
2 test. The cumulative airway patency rate after balloon dilation was compared using Kaplan-Meier survival curves and log-rank testing. Airway patency was defined as the maintenance of improvement of the patient’s clinical symptoms and the increase in tracheobronchial diameter of the stenotic segment after balloon dilation. The increase of tracheobronchial diameter of the stenotic segment was defined by the increase of lumen diameter after balloon dilation on bronchoscopy and/or free passage of the 6-mm-diameter bronchoscope in cases in which passage of the bronchoscope was impossible before balloon dilation.
Results
During the 124 sessions of balloon dilation, 64 tracheobronchial lacerations (51.6%) occurred. Of these 64 lacerations, 60 (94%) were superficial, 4 (6%) were deep, and none were transmural. The sex, cause, and site of stenosis differed significantly between the groups with and without tracheal or bronchial lacerations (Table ).
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Seven sessions of balloon dilation were lost to follow-up immediately after the procedure. A total of 117 sessions of balloon dilation were followed up (follow-up length range, 0.2 to 66 months; mean follow-up length, 5.7 months). The recurrence rate in group A was 31.7% (19 of 60 patients), whereas that in group B was 40.4% (23 of 57 patients) during follow-up. The median (± SD) cumulative airway patency rate was significantly longer in group A than in group B (24 ± 12.4 vs 4 ± 0.8 months, respectively; p < 0.05) [Fig 1 ].
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Iatrogenic airway transmural lacerations are rare, life-threatening conditions that are usually caused by intubation, tracheostomies, and bronchoscopies rather than by thoracic trauma.9 Although we found that tracheobronchial lacerations induced by balloon dilation were very common, occurring during 51.6% of sessions, they left no clinical sequelae due to the absence of transmural laceration. All superficial lacerations healed spontaneously within 1 month, and all deep lacerations healed following conservative treatment for a short time. These findings are in agreement with earlier results, which showed that superficial and deep airway lacerations caused by balloon dilation healed without any clinical sequelae.10 Tracheobronchial balloon dilation, therefore, is a safe procedure, and lacerations induced by balloon dilation appear to be clinically unimportant.
In a case report of a 72-year-old woman with posttracheostomy stricture who underwent surgical treatment for transmural laceration secondary to balloon dilation,7 the transmural laceration did not occur immediately after balloon dilation. Rather, in this patient, the deep laceration progressed shortly after placement of the tracheostomy tube with artificial ventilation. In addition, this patient had several underlying risk factors, including old age and multiple comorbidities. Placement of the tube at elevated pressure and the underlying risk factors were regarded as the factors triggering the progression of a deep laceration to a transmural laceration. Thus, patients with deep lacerations after balloon dilation should be monitored closely, especially those patients with the aforementioned risk factors.
We identified the following three risk factors for tracheobronchial lacerations that are caused by balloon dilation: female gender; strictures caused by of endobronchial tuberculosis or posttracheostomy/postintubation stricture; and lesions at the trachea. Women have been found to be more frequently affected by iatrogenic tracheobronchial lacerations11121314 because they are more predisposed to having a relatively smaller airway diameter than that of the men.11 In addition, the trachea contains a weak, noncartilaginous area (membranous trachea), making the trachea more susceptible to laceration than the bronchus. Furthermore, due to the stiffness of chronic inflammatory strictures caused by endobronchial tuberculosis or posttracheostomy/postintubation strictures, laceration of the tracheobronchial tree after sudden balloon dilation would more likely occur in these strictures than in postoperative anastomotic strictures under noninflammatory conditions.2
Balloon dilation has been shown to be a safe and effective procedure for the treatment of benign tracheobronchial strictures with initial clinical success rates of 68 to 100%.234 However, restenosis occurs in many cases and has been reported to occur at rates from 30 to 80%.2341015 The restenosis rate seemed to be notably high in patients with chronic fibrotic stenosis caused by endobronchial tuberculosis.1015 Tracheobronchial stenosis due to tuberculosis is not uncommon.16 The incidence of tracheobronchial stenosis due to tuberculosis was 15.5 to 18% in patients with active pulmonary tuberculosis.1718 Because it is usually cicatricial stenosis and can involves multiple or long segments of the airway, tuberculous tracheobronchial stenosis was not considered to be treated by balloon dilation alone.1516
In our study, we preferred to dilate a stenosis with the use of a high-pressure balloon catheter rather than a low-pressure balloon catheter because most of our patients (87%; 84 of 97 patients) had chronic tight stenosis caused by endobronchial tuberculosis (n = 72) and posttracheostomy/postintubation stricture (n = 12). This may contribute to the high incidence of airway laceration in this study. However, we found that the group of patients with tracheobronchial lacerations showed better cumulative airway patency (median patency duration, 24 vs 4 months, respectively) and a lower recurrence rate (31.7% vs 40.4%, respectively) than the group without tracheobronchial lacerations. These findings suggest that if a laceration heals promptly without excessive growth of granulation tissue, a good clinical outcome can be achieved due to widening of the lumen of the stenotic segment. Balloon dilation for congenital tracheal stenosis also indicates that rupture of the complete cartilaginous rings is a prerequisite step for increasing the luminal diameter itself.19 Therefore, a superficial or deep laceration should be regarded as an expected result of sufficient balloon dilation, not as a major complication. Some overdilation seems to be adequate in obtaining good results after balloon dilation, especially for chronic tight stenosis. If we chose a balloon catheter with a smaller diameter, there would be more recurrence, although there would be fewer lacerations.
We found that superficial lacerations can heal spontaneously and that deep lacerations can be treated conservatively if the patient is stable and has asymptomatic to minimal pneumomediastinum. However, surgical or interventional treatment is mandatory in patients who present with acute respiratory distress secondary to a laceration.20
We performed balloon dilation using the standard accepted method. That is, bronchoscopy was first used to localize the airway stenosis and to insert a guidewire through the stenosis. A balloon catheter was then passed over the guidewire after withdrawal of the bronchoscope and was positioned within the stenosis with the help of fluoroscopy.6 Fluoroscopy is useful to determine the extent of an airway stenosis, to properly position the balloon within the stenosis, and to monitor the effect of balloon dilation. However, Mayse et al6 have introduced another approach, which consists of bronchoscopic balloon dilation of an airway stenosis without fluoroscopy, and have proved that this approach is safe and effective. By avoiding unnecessary fluoroscopy, radiation exposure is avoided and significant financial savings can be possible. We advocate, however, that fluoroscopic guidance is very useful in achieving precise and safe balloon dilation by monitoring the whole segment of the balloon catheter, although prospective randomized studies comparing the safety and efficacy of these two approaches would be necessary to draw definite conclusions regarding the preferred method.
In conclusion, laceration in the tracheobronchial tree after balloon dilation is relatively common but rarely progresses to transmural laceration. Better clinical outcomes may occur following superficial or deep lacerations after balloon dilation in patients with a benign tracheobronchial stricture; however, additional prospective studies would be needed to confirm this tentative conclusion.
Footnotes
This study was supported by a grant (2004–312) from the Asan Institute for Life Sciences, Seoul, Korea.
None of the authors have identified a conflict of interest.
Received for publication September 18, 2006. Accepted for publication November 27, 2006.
References
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