Written informed consent was obtained from the patient for publication of this case report. A 74-year-old woman (body weight, 51 kg; height, 142 cm; and body surface area, 1.39 m2) with a large anterior mediastinal mass that was partially compressing her trachea was scheduled for emergent tracheobronchial balloon dilation and stent placement. She presented with 4 weeks of dyspnea, cough, and fatigue that had resulted in her being unable to maintain a supine position. She had been prescribed medication for hypothyroidism, which was under control, and had undergone resection of a uterine leiomyoma under spinal anesthesia, without any trouble, when she was 63 years old. Her dyspnea was alleviated in the left lateral decubitus position with a respiratory rate of 20/min and 97% pulse oxygen saturation (SpO2) on room air. She had a soft mass on the anterior portion of the neck, but there was no edema in the upper body. A chest X-ray revealed multiple bilateral pulmonary coin lesions and a mediastinal mass that had infiltrated the right upper lung field (Fig. 1). Preoperative chest computed tomography showed an anterior mediastinal mass, with a largest greatest dimension 90 mm, surrounding the main bronchus (Fig. 2) and the lower trachea, thereby compressing the trachea (shortest diameter, 1.3 mm). Both the superior vena cava and the inferior vena cava were compressed by the tumor. Laboratory tests revealed elevated lactate dehydrogenase (865 units/L), uric acid (9.4 mg/dL), blood urea nitrogen (37 mg/dL), and creatinine (2.3 mg/dL). Pulmonary function tests were not performed because of evident dyspnea. Preoperative bronchoscopy showed no intratracheal invasion of the tumor but the operator insisted on total immobilization using a muscular relaxant during the procedure because of safety concerns.
She was not administered with any anesthetic premedication and was placed in the left lateral decubitus position for surgery. The patient was monitored via continuous electrocardiography, pulse oximetry (SpO2), non-invasive blood pressure measurement, processed-electroencephalogram (SedLine®, Masimo, Irvine, CA, USA; version2000), and capnometry after tracheal intubation. For establishing V-V ECMO circulation, an infusion cannula (18 Fr) and a drainage cannula (20 Fr) were inserted into the right internal jugular vein and the right femoral vein, respectively under local anesthesia without sedation. V-V ECMO was initiated, but the maximum total flow rate reached was 1.6 L/min (31 mL/kg/min), probably because of limited drainage volume. After preoxygenation, general anesthesia was induced using propofol administered via Target Controlled Infusion (Diprifusor model, TE-371, Terumo, Tokyo, Japan) with a target plasma concentration of 3.0 μg/mL, along with remifentanil 0.25 μg/kg/min and rocuronium 50 mg. Inspiratory oxygen fraction (FiO2) was set at 1.0. The patient was shifted to the supine position, and mask ventilation was attempted but the tidal volume obtained was low at approximately 10 ml. Although tracheal intubation with an 8.0-mm internal diameter endotracheal tube was immediately and smoothly performed, the tip placed at a depth of 21 cm, and the tube positioned at the corner of the mouth, her tidal volume remained low at approximately 10 ml, despite high airway pressure (30 cmH2O). Furthermore, SpO2 decreased from 100 to 87% in approximately 5 min after tracheal intubation.
A flexible bronchoscope (outer diameter of 4.9 mm) was inserted to confirm correct tracheal intubation, but the trachea was almost obstructed as it was being squeezed back and forth at the level of the carina (Fig. 3). While observing the area near the obstruction, we found that positive airway ventilation was indeed working and we hypothesized that the patency of the trachea had been improved when the bronchoscope had been inserted to a depth beyond the tumor, which then resulted in successful positive ventilation. A guidewire for the insertion of the balloon and stents was inserted through the internal lumen of the bronchoscope in a way the tip of the wire was positioned beyond the squeezed trachea as observed under X-ray fluoroscopy. Immediately after the removal of the bronchoscope, balloon dilation of the trachea was completed. Next, with the tracheal tube in place, stents were placed at the lower trachea and the left main bronchus under positive ventilation (tidal volume 230 with peak inspiratory pressure of 26 mmH2O). Her SpO2 remained at 100% during the procedure and the CO2 value was approximately 35 mmHg. FiO2 was maintained at 1.0 during anesthesia and after inserting the bronchoscope. V-V ECMO was terminated after the procedure, and her tidal volume increased to 300 mL at a peak inspiratory pressure of 13 mmH2O. Duration of the procedure and run-time for V-V ECMO were 70 and 132 min, respectively.
The patient was transferred to the intensive care unit where she remained sedated with intravenous dexmedetomidine and fentanyl until the next morning. After recovering from sedation, the patient’s trachea was extubated. Her respiratory status had improved dramatically, which permitted her to lie in a supine position without dyspnea. She underwent chemotherapy after the procedure, but the tumor continued to grow. Based on the results of the biopsy and tumor marker values, a diagnosis of extragonadal primary germ cell tumor was made. She developed disseminated intravascular coagulation and passed away on postoperative day 30.