Mask Induction with Sevoflurane in a Parturient with Severe Tracheal Stenosis

A 33-yr-old gravida 2 para 0 woman at 32 weeks of gestation was scheduled for laryngoscopy, bronchoscopy, biopsy, and possible laser ablation of a tracheal obstruction. Her medical history included a respiratory arrest during the first trimester of her previous pregnancy, followed by a prolonged intensive care unit stay, residual right vocal cord damage, and pregnancy loss. In her second pregnancy, she noted increasing shortness of breath and dyspnea on exertion since her second month of gestation.

The patient was admitted to the hospital at 28 weeks of gestation for worsening dyspnea. She reported dyspnea while lying supine, which was relieved when she sat up 30°. She underwent bronchoscopy during local anesthesia with sedation; a subglottic tracheal obstruction was visualized, and a 4- to 6-mm airway opening was identified 4 cm below the vocal cords. Her respiratory symptoms improved markedly after antibiotic and bronchodilator therapy, and her pulmonologist, otolaryngologic surgeon, and obstetrician all agreed to delay biopsy, bronchoscopy, and possible ablation of the tracheal lesion until later in the third trimester to allow for further fetal maturation. The decision was made to observe the patient in the hospital setting in case worsening respiratory compromise should occur. Twenty milligrams intravenous methylprednisolone was administered to the patient twice daily to decrease airway swelling and promote fetal lung maturity.

Before elective surgery at 32 weeks of gestation, the patient was informed of the risk of intraoperative fetal distress and that emergency cesarean delivery might be necessary. She fasted for 8 h preoperatively and was premedicated with 10 mg intravenous metoclopramide, 50 mg ranitidine, and 0.2 mg glycopyrrolate. Intravenous midazolam was also administered in 0.25-mg increments up to 1.5 mg. In addition to standard monitors, an external fetal heart rate monitor and a 20-gauge radial intraarterial catheter were placed. Otolaryngologic surgeons, an obstetric team, and a neonatal team were ready in the operating room in case fetal distress occurred and the need for emergent cesarean delivery occurred. The patient breathed 100% oxygen via  face mask for 7 min. The reservoir bag was then rapidly filled with 8% sevoflurane in 10 l/min oxygen. The patient was asked to take deep breaths, which resulted in her losing consciousness in approximately 40 s. A patent airway was maintained with the patient breathing spontaneously in the supine position with left uterine displacement. Mask ventilation was easy, and 100 mg intravenous succinylcholine was administered to the patient. After paralysis, mask ventilation continued without difficulty. Muscle relaxation was maintained with 40 mg intravenous rocuronium to ensure optimal operating conditions. Anesthesia was maintained with 2% sevoflurane in 100% oxygen and small doses of intravenous fentanyl. Laryngoscopy and bronchoscopy initially proceeded without difficulty, and manual ventilation was maintained through the adult bronchoscope. The initial blood gas showed a pH of 7.32, a partial pressure of carbon dioxide (Pco²) of 40 mmHg, and a partial pressure of oxygen (Po²) of 312 mmHg. However, because the degree of subglottic stenosis was so severe, a pediatric bronchoscope was necessary to proceed with surgery. High inspiratory pressures (up to 70 cm H²O) were necessary to maintain adequate oxygenation. Oxygen saturation never decreased below 94%, and arterial blood gas measurements during this period were as follows: pH, 7.22; Pco², 53 mmHg; and Po², 155 mmHg. On inspection, a very fine tracheal web was visualized. When the web was biopsied with forceps, the airway diameter enlarged to 1.2 cm. Ventilation improved markedly after this, and the otolaryngologic surgeons decided that no further resection of the web was indicated. Ten milligrams intravenous dexamethasone was administered to the patient to minimize airway swelling, and muscle relaxation was reversed. Spontaneous respiration resumed, and the patient awakened before transfer to the postanesthesia care unit. No fetal heart rate deceleration or distress was noted intraoperatively. Although Wegener granulomatosis was suspected, laboratory and pathologic specimens did not confirm this diagnosis. The patient had an uneventful postoperative course and underwent elective cesarean delivery at 37 weeks of gestation for fetal breech presentation during spinal anesthesia without incident. She required no additional therapy for her tracheal stenosis because she was asymptomatic.

Despite apparent contraindications to the use of mask inhalation anesthesia in pregnant patients, mask induction facilitated successful management of this patient. Four cases of tracheal stenosis in pregnant patients have been reported. Pare et al.  2described a patient with tracheal stenosis in whom severe respiratory compromise developed. Salama et al.  3described tracheal balloon dilatation in a patient with a tracheal web, and Mallett et al.  4used a helium–oxygen gas mixture to facilitate respiratory function during labor and vaginal delivery in a patient with subglottic stenosis. In the fourth case report, Sutcliffe et al.  5described a patient with severe tracheal stenosis who underwent cesarean delivery during regional anesthesia but died a month later.

Because the current patient was able to maintain an adequate airway while awake, mask induction was chosen. If respiratory compromise had occurred, alterations in her position might have improved respiratory status. If complete airway obstruction had occurred, we would have discontinued administration of volatile anesthetic to allow the patient to regain consciousness and, hopefully, a patent airway. Gambling et al.  6reported about the safety of sevoflurane in parturients undergoing elective cesarean delivery. Another report described mask induction with sevoflurane for emergency cesarean delivery. 7This report sparked controversy because general anesthesia was induced without intravenous access, 8an issue not relevant to the current case. Mask induction with sevoflurane has been reported in pregnant patients with other conditions. 9,10Ours is the first report of a pregnant patient undergoing mask general anesthesia induction with sevoflurane for severe tracheal obstruction.

The risk of aspiration was of some concern in the current patient because of her pregnancy. Because the surgery was elective, she fasted for 8 h preoperatively, and ranitidine and metoclopramide were administered, this risk was reduced.

When to perform surgery primarily depended on maternal condition. Because the patient’s respiratory status markedly improved after her respiratory infection resolved, her physicians believed that delaying surgery was appropriate. Had her respiratory status deteriorated, she would have undergone surgery immediately. Fetal maturity was a secondary consideration. Because the patient was stable and fetal outcome is significantly better at 32 weeks than at 28 weeks, 32 weeks of gestation was chosen as the optimal time to perform surgery. This decision was made to minimize maternal risk and optimize neonatal outcome. Alternatively, she could have undergone surgery later in the third trimester, but the increased maternal risk was believed to be unwarranted after 32 weeks of gestation.

In summary, this is the first report of a pregnant patient undergoing mask general anesthesia induction with sevoflurane for tracheal stenosis. This technique should be considered in parturients with airway obstruction or when a difficult airway is encountered.