Hui Gao, Bin Zhu,Jie Yi, Tie-hu Ye, and Yu-guang Huang

Department of Anesthesiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China

SEVERE tracheal stenosis can not only cause criti- cal medical problems such as severe shortness of breath, hypoxia, and even orthopnea, but also impose overwhelming challenges on the physicians, particularly the anesthesiologist. Life-threa- tening airway obstruction can make the patient's gas exchange extremely difficult. Though several options could be offered regarding the treatment of tracheal stenosis, normally, tracheal resection and following reconstruction is the first choice for severe airway stenosis.1Successful surgical intervention relies on the close communication and cooperation between surgeons and anesthesiologists. In these cases, airway management is the top issue for the anesthesiologist, and the level of difficulty varies with stenosis location, severity of stenosis, and surgical technique. Extracorporeal membrane oxygenation (ECMO), or cardiopulmonary bypass (CPB), is rarely utilized for the surgery, but for those impossible airways due to nearly complete tracheal obstruction, ECMO or CPB could be the final choice for anesthesiologists.2-4Here we report a case of successful urgent airway management for tracheal resection and reconstruction assisted by temporary CPB.

CASE DESCRIPTION

A 51-year-old woman of 68 kg and 163 cm with severe respiratory distress was referred to Emergency Department, Peking Union Medical College Hospital from a local hospital. She developed a recurrent cough and shortness of breath one year before, especially after physical activities. She was treated as asthma at the local hospital. Her respiratory insufficiency progressively worsened during the month before referral and caused severe symptoms even at rest. Upon her admission, the patient clearly demonstrated a critical airway problem and could not tolerate supine position.

Auscultation of the chest detected bilateral, monophonic inspiratory and expiratory wheeze. Computed tomography (CT) scan of the neck and thorax revealed a tracheal tumor located 4 cm below the vocal cord and 5 cm above the carina, obstructing more than 80% of the lumen (Fig. 1). Fiberoptic bronchoscopy (FOB) was attempted but failed due to bad tolerance of the investigation on the part of the patient. Urgent operation was indicated, but conventional anesthesia technique could be catastrophic since the attempt to intubate even a small single lumen tube would cause full obstruction of the airway. An emergent intrahospital consultation was summoned, attended by physicians from otolaryngology, cardiac, and anesthesiology departments. CPB was decided to be performed before inducing anesthesia as well as for the oxygenation and CO2elimination during tracheal resection and reconstruction.

The patient was thus transferred to the operation room and placed in her preferred right lateral position, with the operation table in reversed trendelenberg position. Lidocaine of 1% with 1/100 000 epinephrine was used for local anesthesia, the right femoral artery and femoral vein were cannulated for CPB. The venous cannula was inserted to reach the right atrium level to obtain a sufficient venous drainage. Heparin (200 mg) was given just before the cannulation, resulting in an activated clotting time of 468 seconds. As soon as the full CPB flow rate was achieved, general anesthesia was induced with propofol, rocuronium, and followed by sufentanil. Laryngoscopy was carried out thereafter before the operation.

FOB confirmed that the 1.6-cm in diameter, smooth, and reddening tracheal tumor obstructed more than 4/5 of the tracheal lumen, but there was no evidence of spontaneous bleeding and/or tumor-friability (Fig. 2). Tracheal intubation guided by FOB was attempted with a 7.0-mm endotracheal tube (ETT). The ETT narrowly but still successfully passed the stenosis, placed just a few millimeters above tracheal carina. Mechanic ventilation was started and successful tracheal intubation was confirmed based on the exhaled CO2. In addition, the monitor of mechanic ventilation did not show abnormal airway pressure under normal ventilation parameters. After brief discussion with the surgeon and the perfusionist, CPB was terminated after running for about 15 minutes and gas exchange was thereafter achieved by mechanical ventilation through endotracheal tube. Protamine of 200 mg was administered to antagonize the heparin.

Tracheal resection and reconstruction was then performed following the standard operation procedure. Briefly, before proceeding to resection of a 2.5-cm tracheal segment, a 6-mm cuffed ETT was inserted through the trachea incision into the left main bronchus by the surgeon for ventilation and the tracheal ETT was withdrawn from above the cut. After tracheal resection, posterior and lateral tracheal anastomosis was performed, and the 6-mm ETT in the left bronchus was extubated and simultaneously the original 7.0-mm ETT in trachea was re-advanced, directed under the help of the surgeon to make sure the cuff was below the anastomosis. During the operation, anesthesia was maintained by the combination of intravenous sufen- tanil, rocuronium, and inhaled isoflurane. Blood pressure was about 115/70 mmHg and heart rate was about 85 beats/minute, similar to the preoperative levels. Arterial blood gas analysis indicated normal ventilation and oxygenation (pH=7.399, PaO2=439.2 mmHg, PaCO2=39.0 mmHg, standard base excess=0.2 mmol/L, hemoglobin saturation=99.9%), when the inspired oxygen was maintained at the concentration of 50%. At the end of the operation, tension suture was performed to prevent neck extension and thereby to limit tracheal anastomotic tension.

Figure 1. Computed tomography scan of the thorax shows the tracheal tumor obstructing over 80% of the lumen.

Figure 2. Fiberoptic bronchoscopy of the tracheal tumor.

With the guidance of FOB, the patient was successfully extubated and discharged after 2 days from the intensive care unit and 14 days from the hospital without difficulty in respiration.

DISCUSSION

This case report presented an urgent surgery for tracheal stenosis, which is the first case of tracheal resection and reconstruction assisted by temporary CPB in our hospital.

Though several treatments are available for tracheal stenosis, tracheal resection and following reconstruction is still the best choice for severe airway stenosis. In the process of tracheal resection, airway management is one of the most challenging parts in anesthesia because of the unique conditions associated with narrowed airway and the problem of maintaining oxygenation and CO2elimination during induction, tracheal resection and reconstruction.5Therefore, anesthesiologists must be very familiar with the major surgical procedures for tracheal tumors. Information such as the location and size of the tumor, the distance from the vocal cord to the top of the tumor, the length of the tumor, and the distance from the bottom of the tumor to the tracheal carina is of great importance, because it directly determines how surgeons will resect the tumor and reconstruct the trachea, which in turn requires anesthesiologists to adopt corresponding strategies suitable for the surgical procedures.5A previous report presented a case of anesthesia management for tracheal tumor surgery.6The tumor was located 7 cm below the vocal cord and 3 cm above the carina, which offered the possibility of direct tracheal intubation above the tumor with a small-size ETT, since the distance between the proximal cuff and the distal tip of a standard 6.5 ETT is approximately 6.5 cm. Under the direct FOB guidance, the length of ETT in trachea was well controlled. In airway reconstruction for tumors located at the lower part of trachea, including those involving the carina, it is a practical approach to keep the endotracheal tubes above the tumors. During the tracheal resection and reconstruction, ventilation was switched between the endotracheal tube and the endobronchial tube with the close communication and cooperation within surgical team.6

Though successful airway management and surgical intervention could be achieved through preoperative preparation and intraoperative cooperation in most cases, critical tracheal stenosis may sometimes still be life- threatening. The present emergent case came to our hospital with acute respiratory distress and orthopnea. Her tracheal was severely obstructed, making her almost lose any chances of airway manipulations, including the FOB investigation. Besides, she was already in an urgent situation upon her arrival at the hospital, which also made the thorough preoperative preparation nearly impossible. Under such circumstance, the technique of CPB was introduced to solve the problem.

Normally, CPB is a rare choice for the tracheal tumor surgery.7Even for serious tracheal stenosis, such as those with about 80% of tracheal lumen obstructed, preoperative laser ablation could still be performed to maintain airway patency and to ameliorate the symptoms.8However, for an emergency case with critical airway occlusion and urgent respiration problems, as well as for the hospitals where laser ablation is not available, the choice before the physician would be very limited. In such situation, CPB could be the last choice for anesthesiologists.

The use of awake ECMO in the surgical management of nearly complete intrinsic airway obstruction was first reported by Collar et al.2The patient in their report presented a localized tumor to the carina with almost complete obstruction of bilateral main bronchi, demonstrated severe shortness of breath and orthopnea. Before the anesthesia induction, a venovenous ECMO was set up, maintained during the treatment, and successfully terminated. However, ECMO was initially designed for possible long-term cardiopulmonary support and could be very expensive, the cost-effectiveness of its utilization for surgical purpose thus needs careful consideration. Chiu et al3reported a case of successful tracheal resection and reconstruction assisted by temporary CPB, yet spinal anesthesia was introduced in that case for the cannulation of CPB, in which almost full dose of heparin was administered just in the period between the spinal puncture and the cannulation, possibly posing a higher risk of epidural hematoma.

In the present case of urgent tracheal resection and reconstruction assisted by temporary CPB, local anesthetics were applied instead of spinal anesthesia for the CPB cannulation. Furthermore, when CPB-supported oxygenation and CO2elimination was set up, tracheal stenosis reassessment and intubation with FOB was attempted, which successfully established the mechanical ventilation and dramatically shortened the CPB time, thereby maximally avoid the CPB-associated complications.

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3. Chiu CL, Teh BT, Wang CY. Temporary cardiopulmonary bypass and isolated lung ventilation for tracheal stenosis and reconstruction. Br J Anaesth 2003； 91: 742-4.

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8. Yasuda M, Hanagiri T, Ichiki Y, et al. Surgical treatment of patients with stenosis of the central airway due to tracheal tumours. Asian J Surg 2010； 33:212-7.