Chapter 9 Bronchoscopic Treatment of Post Tracheostomy Tracheal Stenosis with Chondritis
Case Description
This patient is an 86-year-old woman with a history of ischemic stroke and coma requiring 4 weeks of endotracheal intubation, followed by percutaneous dilational tracheostomy (PDT). She was decannulated 3 months later in the nursing home where she lived because of required assistance for daily living activities. She had been hospitalized previously for respiratory failure due to decompensated congestive heart failure (CHF). She was extubated after CHF was treated, but within minutes of extubation she developed biphasic stridor and had to be emergently reintubated. Three days later, after administration of Solu-Medrol 60 mg intravenously every 12 hours, she was successfully extubated and transferred to the medicine ward. A few days later, however, the intern on call was called to evaluate her for recurrent stridor and increased work of breathing. The chest radiograph (CXR) shown in Figure 9-1 revealed narrowing of the upper trachea, as well as cardiomegaly and pulmonary vascular congestion. Bronchoscopy confirmed radiographic findings and showed a 1.5 cm long triangular stomal stricture 4 cm below the vocal cords. During inspiration, this narrowed the lumen by 80%, but during expiration, 100% airway lumen obstruction occurred as the result of lateral cartilaginous collapse of two tracheal rings (see Figure 9-1). The rest of the airway examination was unremarkable. No evidence of mucus plugging or secretions was found distal to the stenosis. In addition to severe CHF, her medical history included hypothyroidism, hypertension, anemia, Alzheimer’s dementia, and right hemiplegia from her ischemic stroke. Physical examination revealed an elderly woman in mild respiratory distress at rest who followed some simple commands and had biphasic stridor over the anterior neck auscultation. Oxygen saturation was 95% on room air. Karnofsky performance score before the episode of respiratory failure was 50, and American Society of Anesthesiologists (ASA) score at the time of the diagnostic bronchoscopy was 3. Laboratory data were normal. A two-dimensional echocardiogram performed during hospitalization revealed normal left ventricular function, but a moderately enlarged left atrium and diastolic dysfunction were evident. The patient has one daughter, who rarely visits her in the nursing home but has been visiting her during her most recent hospitalization. According to the staff at the nursing home, the patient enjoys watching television and seems to enjoy eating a modified dysphagia diet. At baseline, she follows some simple commands but is aphasic and does not speak.
Discussion Points
1. Describe three qualitative features of tracheal stenosis.
2. Describe three diagnostic modalities other than bronchoscopy that can be performed to assess the severity, extent, and morphology of this patient’s tracheal stenosis.
3. List four therapeutic alternatives for post tracheostomy stenosis with chondritis.
4. Identify three airway stricture characteristics that determine the need for and type of treatment.
Case Resolution
Initial Evaluations
Physical Examination, Complementary Tests, and Functional Status Assessment
The initial diagnosis of tracheal stenosis occurred after a careful examination of the chest radiograph obtained post extubation. Chest radiographs are rarely diagnostic of central airway obstruction yet are often obtained as initial radiologic tests. Obvious pathology such as tracheal deviation from masses or severe tracheal stenosis similar to that seen in this case may be identified; CXR can also reveal changes that may alter the normal airway-vasculature relationship, such as skeletal deformities or mediastinal shift (Figure 9-2). In cases of post tracheostomy stenosis (PTS), the tracheal air column is easily overlooked by radiologists and clinicians alike; thus careful inspection is warranted in a patient who is symptomatic post tracheostomy.1 The CXR does not allow accurate determination of morphology, extent, degree of narrowing, and associated findings such as chondritis (involvement of the cartilage and resulting collapse). From this perspective, standard computed tomography (CT) scans provide much more information and the ability to document airway collapse when performed during both inspiration and expiration. Multiplanar and three-dimensional reconstruction with internal (virtual bronchoscopy) and external rendering (virtual bronchography), with excellent image quality, is achievable with the use of low-dose techniques (Figure 9-3). Analysis using these newer imaging protocols better characterizes whether the lesion is intraluminal, extrinsic, or mixed, and whether the airway distal to the obstruction is patent.2,3 In addition, the length and diameter of the lesions and their relationship to adjacent vascular structures are assessed with a higher degree of accuracy. These features may assist physicians in determining appropriate therapy.4
Magnetic resonance imaging (MRI) has been used in small case series of tracheal stenosis.5–7 Results of these studies show that MRI can be used to identify the relationship of the trachea to adjacent vascular structures, and to determine the degree and length of tracheal stenosis, without the use of ionizing radiation or intravenous contrast medium (Figure 9-4). Following percutaneous dilational tracheostomy, MRI provides an excellent noninvasive method of assessing the integrity of the tracheal lumen.8 Neither MRI nor CT provides information about mucosal changes, and neither can reliably image the integrity of the cartilaginous framework of the airway. Although investigators are exploring the use of high-resolution endobronchial ultrasonography (see Figure 9-3), it appears as of this writing that optical imaging using flexible bronchoscopy remains a procedure of choice to diagnose and identify the type, location, and severity of an airway stricture before therapeutic interventions are proposed.9,10
This patient had developed a postsurgical tracheo-stomy–related stricture 90 days after an indwelling size 8 cuffed tracheostomy tube with 11 mm outside diameter was inserted. The true incidence of PTS is difficult to determine accurately from the published literature because of inconsistent follow-up, but it is estimated to be 1% to 2%.11 The mean onset of strictures seems to be earlier after PDT than after open surgical tracheostomy: 5.0 weeks versus 28.5 weeks (P = .009).12
PTS appears in three locations:
1. Suprastomal stenosis: When defined as involving more than 50% of the lumen, this type of stricture was noted in 23.8% of PDT patients and in 7.3% of surgical tracheostomies in one study.13 The superior level (proximal) of the stenosis was located at a mean distance of 1.6 cm from the vocal cords in PDT patients, and at 3.4 cm from the cords in surgical tracheostomy patients (P = .04). This might be secondary to the use of incorrect needle puncture sites during PDT.
2. Stenoses at the level of the tracheostomy tube cuff: These are caused by ischemic mucosal damage when cuff-to-tracheal wall tension exceeds the mucosa capillary perfusion pressure, usually 20 to 30 mm Hg; subsequent inflammatory histologic changes may occur as soon as within 24 to 48 hours. The incidence of these lesions has been reduced 10-fold after transition to high-volume–low-pressure cuffs. It is therefore warranted that when patients have indwelling endotracheal or tracheostomy tubes, peak inspiratory and expiratory cuff pressures should be kept below 15 mm Hg, and definitely below 25 mm Hg.14
3. Stomal strictures: This is the type of stenosis described in our patient. These stenoses account for more than 85% of cases of PTS.10 They may be secondary to inadequate tracheal incisions, ongoing stomal infection, or a rigid tube-connecting system that generates excess tube motion within the trachea. In one review paper, stomal wound infection was a causative factor in 42% of stomal stenoses following open tracheostomy.15 Strictures may result from abnormal wound healing and excess granulation tissue formation around the tracheal stoma site; excess granulation tissue can also develop over cartilage fractured during tracheostomy.16 Cartilage damage can result from mechanical leverage of the tracheal tube at the stoma site from the unsupported weight of ventilator attachments. This can cause pressure necrosis of tracheal mucosa and the underlying cartilaginous frame. Because risk is high if the tracheostomy tube is too large for the airway, recommendations are to consider a size 8 tube with an 11 mm outer diameter as an upper limit in men, and a size 7 tube with a 10 mm outer diameter in women.14 We presume that the 11 mm external diameter tube used in our patient was probably too large and may have contributed to the development of her PTS.
Symptoms (at rest) in tracheal stenosis usually are not present until a 70% reduction in lumen diameter occurs, but stridor, as seen in our patient, occurs when the tracheal lumen is less than 5 mm in diameter.10 The presence of stridor on neck auscultation is consistent with a bronchoscopic classification of severe airway narrowing signaling greater than 70% airway lumen narrowing.9,17,18 Indeed, based on the Myer-Cotton classification system* for laryngotracheal stenosis, this patient has a grade III lesion because her stenotic index† was 80%.19
In addition to an accurate assessment of airway lumen, the functional status of the tracheal stenosis patient should be part of a multidimensional evaluation. On this note, the Medical Research Council (MRC) dyspnea scale was found to be highly sensitive to the presence of varying degrees of tracheal stenosis. Strong correlation was noted between the severity of the stenosis and the MRC grade. The MRC scale furthermore was found to be responsive to changes in a patient’s effort tolerance resulting from treating the obstructive lesion.20
Comorbidities
This patient had significant comorbidities, including CHF and a history of ischemic stroke. When surgical or bronchoscopic interventions are provided under general anesthesia, comorbidities could significantly increase the risks for perioperative adverse events such as decompensated CHF or new cerebral ischemia.21 Preoperative decompensated CHF, as seen in our patient, has been identified as a risk factor for other cardiac complications after surgery and often requires postponing elective surgery for a week after resolution of symptoms.22 Although a therapeutic bronchoscopic intervention in this patient is not considered a high–cardiac risk procedure (contrary to vascular, intraperitoneal, or intrathoracic procedures), her age greater than 70 years and her previous history of CHF and cerebrovascular disease are independent risk factors for major cardiac complications that need to be seriously considered.23 The presence of cerebrovascular disease is a particularly important finding in elderly patients undergoing general anesthesia. In general, at least 2 weeks should elapse after a stroke before elective surgery is attempted. Furthermore, if recurrent transient ischemic attacks (TIAs) have occurred, an evaluation for carotid artery disease is warranted. Our patient had her stroke several years before her tracheal stricture. No signs of recurrent TIAs were noted, and her CHF had been stabilized for a week before our evaluation.
Support System
The patient was a resident of a nursing home and had poor family support. The quality of social relationships for nursing home residents was shown to have a significant effect on older people’s self-perceived quality of life, life satisfaction, and well-being. Residents of nursing homes consistently report that they experience limited meaningful interaction with others and may feel socially isolated, despite the busyness of a long-term care home.24 Social interaction in these institutions can be difficult and is not always well supported by the environment or the staff. In addition, as noted in our patient, individual factors such as restricted mobility and diminished cognitive ability can further limit interaction with other people.24
Patient Preferences and Expectations
Because of her dementia and post stroke aphasia, the patient was unable to clearly express a desire for treatment. Her daughter, as the next of kin, had durable power of attorney and was the designated health care decision maker. She was informed about available therapeutic options for her mother’s tracheal stenosis, including dilation with airway stent insertion, surgery, and even repeated tracheostomy. Because it was believed that tracheostomy would further compromise her quality of life, this was considered a less optimal alternative. The likelihood of complications resulting from tracheal resection was felt to outweigh the benefits in this particular case because of her cardiac and neurologic comorbidities; in addition, from a surgical standpoint, the risk for anastomotic complications was increased in view of a previous tracheostomy and the high likelihood of peritracheal fibrosis, which limits tracheal mobility and increases tension, potentially leading to catastrophic failure of the anastomosis.25 Thus rigid bronchoscopy under general anesthesia with stent placement was offered to this patient as the therapeutic alternative of choice.
Procedural Strategies
Indications
This was a symptomatic PTS that resulted in stridor and respiratory distress at rest. A bronchoscopic procedure or open surgery may be offered to improve dyspnea, restore satisfactory airway lumen patency, and improve symptoms.9,26 Symptoms in tracheal stenosis are related mainly to the degree of airway narrowing and flow velocity through the stenosis, and to a lesser degree to the extent or morphology of the stricture. The drop in airway pressure along the stenotic area increases significantly at rest when more than 70% of the tracheal lumen is obliterated. Our patient’s inactive lifestyle caused routinely low-flow velocity through her stenotic airway. This explains why she developed symptoms only when a severe degree of airway narrowing was present. Improving airway patency to a lesser (mild) degree of narrowing (<50%) would partially or completely alleviate this patient’s shortness of breath.27 Palliation of her airway narrowing was therefore warranted.
The stricture was 1.5 cm in extent. Although this length is considered of moderate degree and may impact surgical decisions or choice of stent type and length, long stenoses show a modest difference in pressure profile with a slightly smaller magnitude of total pressure drop than the simple shorter and less than 1 cm stenosis of comparable diameter.27 It appears that in terms of flow dynamics and symptoms, the degree of airway narrowing is more important than the extent of stenosis.
Tracheal stricture morphology in this case was triangular. Triangular stenoses have been described as lambdoid, pseudoglottic, or A-shaped strictures. Experimental flow dynamic studies show that this morphologic type of stenosis results in slightly less pressure drop than an elliptical morphology of similar degree of airway narrowing,28 suggesting that an accurate description of the morphologic type (i.e., triangular, circumferential, or elliptical) may impact symptoms and eventually decisions about treatment. To our knowledge, however, no common language or nomenclature has been universally accepted for tracheal strictures.
Contraindications
No absolute contraindications to rigid bronchoscopy were known in our patient. However, the risk for perioperative cardiac complications is almost doubled when clinical signs of CHF are present preoperatively.29 Our patient had no clinical signs of CHF at the time of our evaluation. She was therefore continued on her medicines, which included angiotensin-converting enzyme (ACE) inhibitors, diuretics, and beta blockers. Decompensated CHF (New York Heart Association [NYHA] class IV), if present, should be treated to the extent possible before surgery, and postponement of surgery is often appropriate.30 Regarding her history of cerebrovascular disease, perioperative stroke is an infrequent but serious complication, occurring at a rate of 0.3% to 3.5%, with most cases occurring during the postoperative period.31
Expected Results
In patients with PTS, therapeutic success of rigid bronchoscopic interventions is variable. Factors influencing the success rate include the presence or absence of chondritis resulting in cartilaginous collapse (malacia), a characteristic of complex stenosis. This triangular stenosis, due to loss of varying amounts of anterior and lateral cartilaginous wall, will accept various sizes of dilating instruments, such as rigid bronchoscopes, but generally will not respond more than transiently with an increase in airway cross-sectional area.1 For instance, in one study of patients with complex stenosis, including those with PTS, during a follow-up period of 28 to 72 months, only 22% of patients (n = 13) were treated successfully with laser-assisted mechanical dilation, whereas 47 patients (78%) required stent placement; 22 had their stent removed after 1 year and did not require further therapy. Thirteen inoperable patients required permanent stent insertion, and 12 others were referred to surgery after failure despite numerous repeated endoscopic treatments.32 In another study, all patients with complex stenosis including PTS had undergone tracheal stent placement during an initial rigid bronchoscopy. After 6 months of follow-up, of those patients who continued to be considered inoperable (n = 10), most (n = 9) eventually required permanent bronchoscopic airway stent insertion.9
Team Experience
Experience and expediency might result in reduced complications in this patient with cardiac and neurologic comorbidities. Team experience and an available multidisciplinary airway disease program, including thoracic and ear, nose, and throat surgeons, anesthesiologists, and pulmonologists, can result in the elaboration of specific therapeutic algorithms for patients with this disease. Failure rates, mortality, and morbidity of operative and nonoperative techniques in the published literature and in the operators’ experience should be taken into account to establish a specific therapeutic approach.9
Risk-Benefit Analysis
The risks of postoperative decompensated CHF and postoperative stroke were outweighed by the benefit of improving airway patency to relieve this patient’s respiratory distress and avoid recurrent respiratory failure caused by severe tracheal stenosis. Although tracheal sleeve resection is considered the definitive treatment for this type of lesion, this patient’s poor general health, previous tracheostomy, and cardiac and cerebrovascular comorbidities would significantly increase the risk for postoperative complications after open surgical interventions.33 Therefore, other techniques have been proposed in the literature as alternatives to open surgery.
Therapeutic Alternatives for Restoring Airway Patency
• Dilation using balloon, bougies, or dilators (e.g., Jackson dilators): These tools are usually used if the stenosis shows stenotic hypertrophic fibrotic tissue in a circumferential pattern, which was not seen in our patient. Simple dilation would not be appropriate because cartilage would collapse again once the dilating instruments were removed from the stricture.34
• Laser resection using neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers35: This approach can be successfully used in conjunction with dilation to release the tension of the stricture by performing radial incisions onto the hypertrophic stenotic tissues; because these were not present in our patient, this modality was not a consideration.
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