Acute Management of Unsuspected Subglottic Stenosis by Tracheal Dilation

Abstract

There is scant information in the literature regarding the anesthetic management of patients in whom unexpected subglottic stenosis is encountered during tracheal intubation. In two previously reported cases, the stenotic regions were lower in the trachea, enabling smaller tracheal tubes to be placed above the stenosis [1,2]. We describe a patient in whom subglottic stenosis immediately below the cords was diagnosed during attempts to intubate the trachea. The surgical procedure was completed after the stenosed area was dilated with laryngeal dilators to allow an adequate-sized tracheal tube to be placed. Case Report A 41-yr-old female was scheduled for total abdominal hysterectomy and bilateral salpingo-oophorectomy because of a rapidly growing pelvic mass. The patient gave a history of long-standing cough with thick secretions and gastric reflux. Surgical history included an uncomplicated cholecystectomy approximately 10 yr prior to this admission. Medications included an oral antacid as needed. Physical examination of the patient revealed a 170-cm tall, 74-kg female with no apparent abnormalities of the airway, and normal heart and lungs. Vital signs and laboratory values were normal. After the patient breathed 100% oxygen and intravenous (IV) pretreatment with D-tubocurarine 3 mg, a rapid sequence induction of anesthesia was performed with thiopental and succinylcholine IV. Orotracheal intubation was then attempted while cricoid pressure was applied. Laryngoscopy yielded good visualization of the vocal cords, but resistance was encountered while attempting to pass a 7.5-mm (inside diameter [ID]) cuffed tracheal tube. The patient was easily ventilated manually via a bag and mask between attempts at intubation and SaO2 remained higher than 98%. Anesthesia was maintained with 1%-1.5% isoflurane in oxygen and muscle relaxation was maintained with intermittent doses of vecuronium. Attempts with 7.0-, 6.5-, and 6.0-mm (ID) tracheal tubes also were unsuccessful. Although each tube could be passed between the cords, it could not be advanced further. After several attempts, a 5.5-mm (ID) cuffed tracheal tube was passed just beyond the vocal cords, and held in place to prevent dislodgment of the tube. There was no leak around the tube at 25-30 cm H2 O. Fiberoptic bronchoscopy, which was performed after the tube was temporarily removed, revealed marked narrowing in the subglottic area. Rigid bronchoscopy, performed by an otolaryngologist, confirmed the presence of a 50% circumferential stenosis involving a 2.5- to 3-cm length of the subglottic region. Cricoid pressure was maintained during airway intervention. However, it became necessary, at times, to "ease" cricoid pressure to ensure airway patency during intubation attempts and instrumentation. Due to the rapid progression of the pelvic disease, the anesthesiologist, gynecologist, and the otolaryngologist all agreed to proceed with the operation after dilating the trachea. Initial dilation allowed a 20 Fr dilator, but a 22 Fr with difficulty. The trachea was dilated by introducing successively larger dilators, up to 42 Fr. The goal was to dilate the stenotic segment to accommodate a reasonable sized tube intraoperatively and to ensure an adequate airway after tracheal extubation. A 6.0-mm (ID) cuffed tracheal tube was then placed without any resistance. A slight leak at 25 cm H2 O necessitated cuff inflation with 2 mL of air. Controlled ventilation was accomplished easily and a normal capnogram was observed. During the surgical procedure, which lasted 3.5 h, a large ovarian tumor weighing 4.1 kg was removed without complications. After the operation was completed, the patient was taken to the surgical intensive care unit tracheally intubated, while breathing spontaneously. Arterial blood gases with an FIO2 of 0.3 were satisfactory. The patient received dexamethasone 12 mg IV in the operating room followed by 8 mg and 4 mg at 12-h intervals. The next day, the patient was returned to the operating room, and after demonstrating a leak at 20 cm H2 O around the tube, the trachea was extubated. She was observed closely in the intensive care unit for signs of airway obstruction. The patient remained asymptomatic and was sent home on the fifth postoperative day. At followup with the otolaryngologist, 3 wk after discharge, the patient was asymptomatic. Discussion Subglottic stenosis may be congenital or acquired. With congenital subglottic stenosis, varying degrees of stridor are usually present after birth. The stridor becomes worse as the child grows, and is precipitated when there is an upper respiratory infection. The most common causes of acquired subglottic stenosis are prolonged tracheal intubation and tracheostomy, especially a high tracheostomy. The incidence after prolonged intubation varies from 6% to 21% [3] and from 0.6% to 21% after tracheostomy [4]. Other causes of acquired subglottic stenosis include tumors, inflammatory conditions, cricoid fractures, burns, or ingestion of caustic substances. Gastroesophageal reflux has been highlighted as a cause of idiopathic subglottic stenosis [5-7]. Repeated low-grade aspirations of gastric acid into the trachea contribute to or aggravate preexisting tracheal stenosis [5-7]. Although the etiology of subglottic stenosis in our patient is uncertain, gastroesophageal reflux might have been a contributing factor. In symptomatic patients, the diagnosis of subglottic stenosis can be made easily by conventional radiographs, xeroradiographs, and computed tomography. Direct laryngoscopy and bronchoscopy determine the extent of the stenosis. When the diagnosis is made, the treatment methods of subglottic stenosis include repeated tracheal dilations, steroids, laser resection, and/or open surgical repairs. When the patient comes to the operating room for reconstructive surgery, deep inhaled anesthesia without muscle relaxants, and spontaneous ventilation until the airway is established, has certain advantages. With severe airway obstruction, even the anesthetized patient can exchange gases adequately during spontaneous ventilation, whereas positive pressure ventilation may be difficult through a limited orifice [8]. Asymptomatic patients with undiagnosed subglottic or tracheal stenosis pose a challenge to the anesthesiologist. The stenosis is first suspected during attempts to intubate the trachea when the tube passes between the vocal cords, but resistance is encountered when it is advanced through the stenotic area. The anesthetic management may depend on several factors, including whether the tracheal stenosis is well below the glottis or high in the subglottic region. If the stenosis is low in the trachea, an adequate-sized tracheal tube may be placed with its distal tip below the cords, but above the stenotic area, and the surgical procedure can be completed [1,2]. The presence of stenosis in the subglottic region or close to the larynx, leaves the anesthesiologist with few options. In a non-urgent situation, the patient can be awakened and evaluated by an otolaryngologist for definitive treatment. If the surgical procedure is urgent, depending on the type and duration of the procedure, anesthesia can be continued via a mask while the patient is breathing spontaneously. In a situation where mask ventilation is undesirable, or becomes difficult, ventilation may have to be provided through other means. Various forms of jet ventilation have been used successfully for patients undergoing tracheal reconstruction for stenosis, including a long narrow catheter [9] and a small tracheal tube [10]. Intermittent jets of oxygen at 50 psi via a 5-mm (ID) cuffed tracheal tube provide a pressure gradient sufficient to achieve an adequate flow rate across the stenosis to maintain adequate ventilation and oxygenation [10]. Another alternative is to perform tracheostomy. The role of the newer airway adjuncts, laryngeal mask airway and the esophageal tracheal doublelumen airway (Combitube Registered Trademark; Sheridan Catheter Corporation, Argyle, NY), are not clear at this time in the management of subglottic stenosis. In our patient, postponing the procedure to provide definitive treatment of the stenosis was not an option because of the rapidly growing tumor. Delivering anesthesia by face mask was undesirable because of the length of the procedure and the need for intermittent positive pressure ventilation and muscle relaxation. We might have been able to place a 4.5- or 5.0-mm (ID) tube through and beyond the stenosis. We chose not to insert such a small tube because of the marked increase in airway resistance, especially if the tube had been left in place, while the patient is breathing spontaneously in the early postanesthetic period. In addition, even with a small tube, postintubation laryngeal edema and airway obstruction can occur. The use of laryngeal mask airway or Combitube Registered Trademark was thought to be inappropriate since the patient was at risk for aspiration of gastric contents because of the esophageal reflux and the large abdominal mass. One of the methods of emergency management of obstructed airway in patients with diagnosed subglottic stenosis is dilation of the stenotic area under direct vision using rigid bronchoscopy and esophageal bougies [11]. We used this method in our patient to facilitate intubation with an adequate-sized tracheal tube, thus avoiding the use of jet ventilation or tracheostomy. The airway resistance imposed by a 6.0-mm (ID) cuffed tracheal tube, which was placed after dilation, is substantially less than that of 4.5- or 5-mm (ID) tubes. The patient was breathing comfortably through the 6.0-mm (ID) tube until the trachea was extubated and the postoperative course was uneventful. This method of managing the patient with subglottic stenosis in an acute setting has not been reported previously and we believe that it should be considered as an option in selected patients.