A 72 year-old, 150 cm, 57 kg, female patient presented with a neck mass that developed a few years earlier. She had no specific medical records except for taking medication for hypertension for 2 years. A physical examination revealed a palpable, broad, and firm tumor around both thyroid glands, but she did not complain of any symptoms. Neck CT detected a thyroid neoplasm on both sides (about 6 × 3 cm on the right thyroid gland; about 7 × 7 cm on the left thyroid), which revealed the presence of tracheal stenosis. The region of tracheal constriction narrowed from 3.6 mm below the glottis to the sternal notch, in which the narrowest lumen of the trachea was approximately 3.9 × 21 mm in diameter and appeared to be compressed by the tumors of both sides (
Fig. 1). Intratracheal metastasis was not suspected. A thyroid papillary carcinoma was diagnosed by an aspiration biopsy, and on thoracic CT, a concern of metastasis into the lung urged immediate treatment. Arterial blood gas analysis (ABGA) showed a pH of 7.424, PaCO
2 of 43.1 mmHg, PaO
2 of 74.8 mmHg, and Base Excess of 2.9. A pulmonary function test was not performed due to the patient's persistent refusal. After admission, diabetes was diagnosed and insulin treatment was started. The patient was scheduled for a thyroid resection and radical neck dissection. The distance between the glottis and constriction site was so short that an endotracheal tube could not to be placed above the constriction region. A tracheostomy was not possible because the tumor covered the site. However, there were no episodes of respiratory disturbance despite the severe tracheal obstruction, nor was there any increase in the PaCO
2. The partial pressure of oxygen (PaO
2) also was in the normal range for her age. Upon auscultation, normal breathing sounds were heard, which made us suspect that the tracheal obstruction was mobile. After explaining the potential difficulty of endotracheal intubation due to the tracheal stenosis one day before surgery, the patient provided informed consent for the procedure. A flexible fiberoptic bronchoscopy and laryngeal mask airway (LMA) were prepared, and uncuffed endotracheal tubes, 4.0, 4.5, 5.0 in size, and cuffed endotracheal tubes, 4.0 to 7.0 in size, were ready for use. For pre-anesthesia medication, 0.5 mg of atropine was administrated 30 minutes before the onset of anesthesia. An electrocardiogram (ECG), non-invasive blood pressure (NIBP) monitor, and pulse oximetry were placed after arriving in the operating room. Her vital signs indicated a BP, heart rate and oxygen saturation of 145/85 mmHg, 92/min and 99%, respectively, and she did not complain of any discomfort in the supine position. Before the onset of anesthesia, denitrogenation was induced with 100% oxygenation at 6.0 L/min for 5 minutes. Because she had no dyspnea during sleep, we tried to attempt endotracheal intubation using bronchoscope during sleep. Midazolam 3 mg was administered and the patient fell asleep. However, when a bronchoscope intubation was attempted, her spontaneous respiration stopped and support ventilation was provided. When assisted ventilation with 100% oxygen was confirmed to function well, thiopental 100 mg was administered and the ventilation function was reconfirmed. Therefore, the possibility of using a laryngoscope rather than a bronchoscope was considered. Succinylcholine 50 mg was then administrated and endotracheal intubation was attempted. After inserting an uncuffed endotracheal tube of 4.0 without resistance, the tube was withdrawn while keeping the bronchoscope in place. When a cuffed endotracheal tube (size 5.0) was inserted without difficulty, the tube was replaced smoothly with a cuffed endotracheal tube (size 6.5). Rocuronium 30 mg was then injected into the vein and anesthesia was maintained with both oxygen and nitrous oxide of 1.5 L/min, and sevoflurane 1.0-2.5 vol%, while remifentanil was administrated continuously as a supplement. The tidal volume (TV), respiratory rate (RR) and peak inspiratory pressure (PIP) was 500 ml, 10/min, and 18 cmH
2O, respectively. The operation was started after placing a catheter into the left dorsalis pedis artery for continuously monitoring of the arterial blood pressure and ABGA. Eight hours and 40 minutes after its onset, the operation was completed uneventfully. Extubation was performed after confirming that the patient's spontaneous breathing was restored and she had reached consciousness. She was transferred to the Ward after sufficient monitoring in the post-anesthesia recovery unit.