Rumbak, Mark MD, FCCP^*; Dryer, Joseph DO^*; Padhya, Tapan MD^†; Camporesi, Enrico MD^‡; Karlnoski, Rachel PhD^‡; Mangar, Dev MD^‡

Subglottic stenosis (SS) has been reported to be associated with various conditions, such as tracheotomy, trauma caused by intubation, sarcoidosis, gastroesophageal reflux, and Wegener granulomatosis (WG). Idiopathic subglottic stenosis (ISS) is diagnosed when all the other causes of SS are eliminated.¹ WG usually presents as a systemic disease with the involvement of the sinuses, lungs, and kidneys. Occasionally, WG affects the trachea alone.² The detection of SS during pregnancy is rare. We describe 2 patients who presented during the third trimester of pregnancy with SS, and discuss their anesthetic and surgical management.

CASE 1

A 21-year-old G₁P₀ presented with increasing difficulty in breathing, which progressed to an obvious stridor. She was in her third trimester of pregnancy. Two years before, she had presented with difficulty breathing and stridor, and was diagnosed with ISS after an extensive work-up, which failed to determine a cause. At that time, she was successfully treated with argon plasma coagulation and balloon dilation of the stenosed area. Follow-up clinic visits indicated no evidence of recurrence of her initial symptoms. During the 27th week of gestation, she presented with restenosis at the original location. On flexible bronchoscopy, the tracheal lumen diameter was measured to be approximately 5 mm and the stenosis extended for 1 cm in length. As our patient was in the third trimester of her pregnancy, we decided to palliate her symptoms with therapeutic bronchoscopy under local anesthesia. Fetal heart rate was measured throughout the procedure. The patient was breathing spontaneously and received 4 mL of 4% lidocaine through the nebulizer. Bilateral superior laryngeal nerve block was carried out with 2 mL of 2% lidocaine injected 2 mm just above the horn of the thyroid cartilage on either side. During bronchoscopy, another 2 mL of 2% lidocaine was sprayed over the SS. An electrocautery knife (Boston Scientific) was used to make an incision longitudinally across the stenosis at a setting of 40 W (ERBE) (Fig. 1). A 0.035 guidewire Jagwire (Boston Scientific) compatible with a CRE (Controlled Radial Expansion) Pulmonary Balloon Dilator (Boston Scientific) was passed through the working channel of the bronchoscope and into the left mainstem bronchus. The bronchoscope was withdrawn keeping the guidewire in place. The CRE Pulmonary Balloon Dilator was inserted over the guidewire and placed across the stenotic area. Its position was confirmed by direct vision with a pediatric bronchoscope placed along its side, avoiding radiation. The Alliance II Inflation System (Boston Scientific) was attached to the balloon and the balloon was blown up to a diameter of 15 mm. This was held for 30 seconds and repeated once after a few minutes. The patient was prewarned and told to hold her breath during the dilation (Fig. 2). Both the patient and the fetus tolerated the procedure well. After the procedure, the patient's symptoms were greatly improved, and the patient went on to deliver at term without complications or recurrence of symptoms of ISS to date.

FIGURE 1.

FIGURE 2.

CASE 2

A 20-year-old pregnant female, G₁P₀, presented in 2007 with worsening dyspnea during the 32nd week of gestation. She complained of increasing difficulty in breathing, productive cough, and general malaise. In addition, the patient noted that her throat felt “tight.” On physical examination, mild biphasic stridor and moderately edematous tonsilar tissue were noted. A flexible laryngoscopy was performed and a circumferential SS detected with a tracheal lumen of 6 mm. Spirometry showed a moderate-to-severe fixed airflow obstruction with a forced expiratory volume in 1 second of 58% and a peak expiratory flow of 33% of predicted. In 2005, the patient was diagnosed with WG and treated with prednisone and cyclophosphamide. Since then, the patient had been on low-dose maintenance prednisone. The patient had been admitted multiple times for difficulty breathing but had refused elective tracheotomy. When the trachea was surveyed, 3 distinct rings of web-like stenosis were found beginning approximately 2 cm below the vocal cords still within the subglottic region.

This patient was closer to the end of pregnancy and the decision was taken to palliate her symptoms with therapeutic bronchoscopy. She was lightly anesthetized with a halogenated agent after intubation with propofol and succinylcholine. The tracheal dissection was completed through an 8.5-mm endotracheal tube. The superior stenotic ring was incised at the 2 o'clock position, the next one at 11 o'clock, and the third at the 1 o'clock position using the technique and settings described earlier. This facilitated balloon dilation that was also carried out using the method described earlier, except for the fact that the procedure was performed through an 8.5-mm endotracheal tube. After dilation, the patient did well and delivered at term.

Fourteen months after the initial dilation procedure, the patient started experiencing reoccurrence of her dyspnea. The patient was not pregnant at this time. A repeat bronchoscopy showed a 50% SS 1.5 cm below the vocal cords extending for 0.5 cm in length. The lesion was dilated with a rigid bronchoscope and neither laser incision nor balloon dilation was used. The patient's difficulty in breathing resolved and has not reoccurred since.

DISCUSSION

In most patients, SS is because of either tracheal trauma caused by intubation, sarcoidosis, infection, or gastroesophageal reflux.^1–3 WG-related SS and ISS are both very uncommon; encountering them during pregnancy is even more rare.^1,4,5 We present 2 patients with SS who were in their third trimester of pregnancy and discuss the surgical and anesthetic management that differs from that for nongravid patients in the following aspect. First, both these patients had severe SS and were very symptomatic. Second, consideration had to be made for the safety of the mother and the fetus before deciding on any treatment approaches. Third, reports with nongravid patients in the literature typically address results of more invasive procedures, such as laser ablation/dilation or tracheal resection therapies.^1,2 Fourth, anesthetic management requires special consideration in pregnant patients.

In our first patient, local anesthesia was sufficient and avoided the side effects of other systemic anesthetic agents. The second patient was closer to the end of pregnancy and was lightly anesthetized with a halogenated agent after intubation with propofol and succinylcholine. In both patients, dilation was carried our under direct visualization to avoid fluoroscopy-related radiation.

During pregnancy, the body develops anatomic and physiological changes involving the respiratory and cardiovascular systems. The respiratory tract undergoes hyperemia and edema of the mucosa and increased secretions because of high estrogen levels. This is worse during the third trimester. The raised diaphragm is offset by an increase in the diameter of the ribcage. Functional residual volume and the total compliance are decreased. During the third trimester, the diffusion capacity is decreased whereas oxygen consumption and carbon dioxide production are increased. The partial pressure of O₂ is decreased. There is a 30% to 40% increase in tidal volume and minute ventilation. Expiratory reserve volume falls by 20%. The cardiac output, stroke volume, and heart rate are all increased during the later stages of pregnancy, reducing the overall reserve.⁶

During labor, the rate of respiration increases dramatically because of pain and anxiety.⁶ The severe tracheal obstruction in these patients could have an adverse effect on labor and delivery. The airway resistance increases by a factor of 4 and this would make the movement of air in and out of the trachea very difficult. It was suspected that our patients would have tired quickly, as they could not have coped with the increased demands of labor, namely, increased resistance of airflow into the trachea, hyperemia on top of an already increased secretion production with minimum cardiac reserve, and an already increased oxygen consumption and carbon dioxide delivery. We feared that these patients could not undergo a vaginal delivery safely. Thus, we decided to palliate the symptoms until the time of delivery.

The safety of the mother and fetus was of paramount importance during the procedure. Both patients refused tracheotomy as an option and we decided to treat the SS endoscopically with tracheotomy. Leventhal and coworkers⁷ used a flexible bronchoscope for awake patients when treating SS. We chose the same instrument as it would allow the use of a local anesthetic and as little systemic anesthetic drugs as possible.

Parsa et al⁸ described a case similar to our 2 cases in which a general anesthetic was given. In summary, they mask ventilated the patient with sevoflurane or halothane and intubated with a size 4 tube. They described the use of an oscillating ventilator or a helium and oxygen mixture.

Surgical resection with end-to-end anastamosis is generally considered to be the definitive treatment, especially for patients with recurrences of the stenosis.^2–4 This surgery has also proven to be effective in the Wegener's subpopulation receiving concurrent immunosuppressive therapy. Obviously, these operations would have been unsafe in our patients.

In our patients, the SS was incised radially (Fig. 1) in direction, or like “rabbit ears,” a V-shaped incision, and subsequently dilated using a balloon catheter. Darjani and associates¹ also had a favorable outcome using the neodymium-doped yttrium aluminium garnet laser to remove the excessive tissue in the trachea in a similar situation. Finally, if general anesthesia is used in pregnant patients, special precautions should be taken.⁸

We believe that incision of SS with a laser, argon plasma coagulation, or an electrocautery knife followed by balloon dilation is a safe initial step in relieving the tracheal obstruction during late pregnancy. This can safely be performed under local anesthesia and conscious sedation if needed. In patients with WG, SS has a much higher likelihood of recurrence.⁴ In these patients, if the symptoms recur after an initial noninvasive treatment, it may be beneficial to consider earlier tracheal anastomosis surgery, rather than having to repeat a dilation numerous times. Consideration should also be made for curative treatment before any possible or planned pregnancies, when recurrence is more likely.^1,5,8

Many of these patients are misdiagnosed as asthmatic and the diagnosis is delayed until this late stage. We recommend including SS in the differential diagnosis of new onset of dyspnea and wheezing during pregnancy.

REFERENCES