Robot-assisted thoracoscopic tracheal carina resection and reconstruction under spontaneous-ventilation anesthesia with a single-lumen endotracheal tube: case report and literature review.

Introduction
Tracheal tumors are relatively rare, accounting for about 2% of respiratory tumors. Surgical resection is the most common method for treating malignant tracheal tumors. Thoracotomy is a common method for treating tracheal carina tumors. With the advancement of medical technology and the update of surgical instruments, it has become feasible to remove tracheal tumors using minimally invasive techniques such as thoracoscopic or robot-assisted techniques [1, 2]. During open and thoracoscopic tracheal resection and reconstruction surgery, mechanical ventilation with bilateral endotracheal intubation or spontaneous-ventilation anesthesia with laryngeal mask has its disadvantages, the former has a great impact on the surgical operation, such as difficulty in entering the posterior wall of the trachea by surgical instruments, affecting the anastomosis of the tracheal stumps [3]. The latter, however, results in insufficient ventilation when inserting a laryngeal mask to preserve the patient’s spontaneous breathing. After the trachea is severed, it is impossible to ensure adequate oxygen concentration and oxygen flow, which can easily lead to severe hypoxemia, or it is impossible to simultaneously perform intra-airway oxygenation and sputum and blood suction. Besides, the latter requires careful selection of suitable patients and has the defect of a narrow scope of application [4, 5]. Currently, minimally invasive thoracoscopic technology has been reported in carina resection and reconstruction, and there are a few reports of cases where robot-assisted technology was used to complete carina resection and reconstruction. However, there have been no reports of the use of robot-assisted technology to perform this surgery under spontaneous breathing anesthesia. Here, we describe a case of successful robot-assisted thoracoscopic tracheal carina resection and reconstruction using a single-lumen tube intubation to preserve the patient’s spontaneous breathing combined with small tube oxygenation.

Case presentation
On September 26, 2024, our center received a 58-year-old male patient (180 cm in height and 59 kg in weight), who complained of blood in sputum and gradually worsening dyspnea. Lung CT showed a mass (26*15 mm) at the tracheal carina, blocking more than 90% of the trachea (Fig. 1). The patient was recommended to be hospitalized for treatment. Fiberoptic bronchoscopy showed a neoplasm in the carina, and a biopsy showed squamous cell carcinoma of the carina (Fig. 2). The patient had previously undergone right middle and lower lobectomy for pulmonary nodules on September 27, 2022. Postoperative pathological examination showed squamous cell carcinoma, pT2bN0M0. The diagnosis of this admission was tumor recurrence, invading the tracheal carina, and 90% of the carina was blocked. After multidisciplinary discussion, the patient underwent chemotherapy (albumin paclitaxel 426 mg + nedaplatin 110 mg, D21) + immunotherapy (carrelizumab 200 mg, D21). After two cycles of chemotherapy, the patient’s hemoptysis and dyspnea symptoms completely disappeared, and chest CT showed significant shrinkage of the carinal tumor, which was evaluated as approaching clinical complete remission (cCR) (Fig. 3), but it was impossible to determine whether it was pathologically complete remission (pCR). After obtaining the patient’s informed consent, the patient and his family decided to undergo robot-assisted thoracoscopic carina resection and reconstruction.

Anesthetic considerations
Only the right upper lobe and left lung are available for the patient to breathe because of a history of right middle lobectomy and right lower lobectomy. The operation required the removal of the carina, anastomosis of the proximal trachea with the left main bronchus, and then end-to-side anastomosis of the right upper lobe bronchus with the trachea. After discussion, we chose to perform the surgery through single-lumen endotracheal intubation and retain the patient’s spontaneous breathing, rather than laryngeal mask ventilation to retain spontaneous breathing and bilateral endobronchial intubation with machine-controlled breathing.
After the patient was transferred from the general ward to the operating room, routine monitoring was performed, oxygen was inhaled by mask (8 L/min), and 5 ml 1% lidocaine (50 mg) was taken orally for 1 min and then swallowed. Ten minutes later, 0.5 mg of longtonine, 5 mg of remimazolam, 5 mg of esketamine, 2 mg/kg of propofol, 10 ug of sufentanil, and 10 mg of rocuronium bromide were intravenously injected. Subsequently, under the guidance of fiberoptic bronchoscope, 20 mL of 2% lidocaine and tetracaine mixture was used for surface infiltration anesthesia of the glottis, trachea, carina, and bilateral main bronchi. During this period, the patient’s vital signs were monitored. When oxygenation decreased, mask-assisted ventilation was given to maintain oxygenation. A 7.0# single-lumen tube was then inserted under the guidance of fiberoptic bronchoscope to 3 cm above the carina. Anesthesia was then maintained by inhalation of sevoflurane 0.8% ∼ 1.0%, intravenous infusion of dexmedetomidine 0.5 ug/kg/h, remifentanil 0.01 ∼ 0.05 ug/kg/min, and propofol 3 ∼ 5 mg/kg/h.
Before the operation, the surgeon injected 2 mL of 0.75% ropivacaine around each incision for local infiltration anesthesia. After entering the chest cavity, the inhaled anesthetic was discontinued, and 3 mL of 1% lidocaine was used to block the right vagus nerve to reduce the vagus nerve reflex. Then ropivacaine was used to block the T3-10 paravertebral intercostal nerves (2 ml of 0.75% ropivacaine per intercostal space), which can reduce pain during the operation and ensure the stability of the patient’s spontaneous breathing during the operation. Finally, 5 mL of 1% lidocaine was used to spray anesthesia on the lung surface to reduce the influence of lung tissue traction on the patient’s spontaneous breathing. Subsequently, the patient was induced to recover spontaneous breathing in the synchronized intermittent mandatory ventilation-pressure control (SIMV-PC) mode, so that spontaneous breathing was restored to a tidal volume (TV) of 200 mL and a respiratory rate of 10 times/min, and then changed to spontaneous breathing (Spontaneous) mode (Fig. 4). After the carina was removed, the sterile suction tube was inserted into the distal end of the left main bronchus through the single-lumen endotracheal tube and the end-expiratory monitoring hole at the threaded tube interface through the anesthesia single-lumen tube, and an external high-flow ventilation device was connected to pure oxygen to ensure the oxygen concentration of left lung ventilation. Oxygen was given through the ventilator through the single-lumen tube with an oxygen concentration of 100% and a flow rate of 15 L/min to ensure the oxygen concentration of right lung ventilation. Suction was intermittent during the operation to ensure the patency of the open trachea (Fig. 5). After the operation, sputum was fully suctioned and the lung was inflated. The bleeding and air leakage of the anastomosis of the patient were observed, and sufficient suction was given to prevent blood and secretions from entering the airway (Fig. 6). After the anastomosis, the SIMV-VC mode increased the patient’s TV and minute ventilation to improve hypercapnia, and 5 mg of oxycodone was injected intravenously (Fig. 7). After the surgical incision was closed, 5 mL of 0.75% ropivacaine was added locally to the incision for postoperative multimodal analgesia. In this surgical case, bispectral index (BIS) monitoring was used to monitor the depth of anesthesia, which is the most commonly used method in clinical practice to ensure the stability and safety of patients during the entire anesthesia process. During the entire operation, the patient’s spontaneous breathing was stable, oxygenation and various vital signs were within normal ranges, and hypercapnia was also within controllable range (Figs. 4, 5, 6 and 7, and Table 1).

Surgical procedures
Only the right upper lobe and left lung are available for the patient to breathe because of a history of right middle lobectomy and right lower lobectomy. The operation required the removal of the carina, anastomosis of the proximal trachea with the left main bronchus, and then end-to-side anastomosis of the right upper lobe bronchus with the trachea (Fig. 8). After the patient was satisfied with the anesthesia, he was placed in the left side position. After routine disinfection, a sterile drape was laid. Local anesthesia was performed around the surgical incision set in the figure below and holes were made and the robot equipment was connected (Fig. 9). After successful installation, the operation began. After entering the chest cavity, the right vagus nerve, intercostal nerves and lung surface were anesthetized. While ensuring the patient’s spontaneous breathing with a small tidal volume, the upper esophagus was freed, and the esophagus was lifted to gradually expose the trachea, tracheal carina, right upper lobe bronchus and left main bronchus. Then scissor was used to cut off the trachea and the left and right main bronchi 2 cm above and below the carina. After the tracheal secretions and blood were completely aspirated, the bleeding was completely stopped, and the anesthesiologist was asked to insert a sterile suction tube through a single-lumen tube to the distal end of the left main bronchus, and the suction tube was connected to the pure oxygen equipment to pass pure oxygen. The intraoperative frozen pathological report showed that the resection margins of the trachea and the left and right main bronchi were negative. An end-to-end anastomosis was performed between the proximal trachea and the distal left main bronchus. After the anastomosis was completed, the lung was inflated after water injection into the chest cavity, and no air leakage was found at the anastomotic site. Continue to introduce oxygen into the left lung through the suction tube, then a scissor was were used to cut a hole in the wall of the tracheal cartilage ring about 2 cm above the right side of the anastomosis between the trachea and the left main bronchus, the size of which was comparable to the size of the bronchial lumen in the upper lobe of the right lung. Then the hole was anastomosed end-to-side with the right upper lobe bronchus. No leakage was found in the anastomosis. According to statistics, the end-to-end anastomosis of the trachea and the left main bronchus took about 25 min, and the anastomosis of the trachea and the right upper lung bronchus took about 20 min. The operation was successfully completed.

Follow up
After the operation, the patient woke up immediately in the operating room and successfully removed the single-lumen tube. After being monitored in the anesthesia intensive care unit for half an hour, the patient reported no pain, good breathing coordination, and the ability to cough up sputum and ventilate on his own. He was then transferred to the general ward of the thoracic surgery department. In the general ward, the patient’s postoperative VAS score was 2 points, diclofenac sodium was given for analgesia. The patient was conscious and cooperative, and maintain the head down and neck bent position to avoid tearing the anastomosis. The patient recovered well after the operation. Postoperative pathology showed pCR with negative tracheal resection margin. A small amount of bubbles escaped from the chest bottle 1–5 days after the operation and was considered to be lung tissue rupture and leakage. The chest drainage tube was removed on the 6th day after the operation as the air leakage stopped and the color and amount of pleural drainage fluid were normal, with CT reexamination on the 6th day after operation confirmed that there was no obvious air and effusion in the thorax (Fig. 10). The patient was discharged smoothly 9 days after the operation.

Discussion and conclusion
Tracheal carina resection and reconstruction is a difficult technique, and thoracotomy is the most common method for tracheal tumor resection and reconstruction [6]. However, with the advancement of instruments and the improvement and innovation of surgical techniques, thoracoscopic or robot-assisted techniques have gradually become alternative methods for tracheal tumor surgery [7–9]. However, no matter which approach is chosen for this operation, intraoperative airway management and reconstruction are crucial and require close cooperation between surgeons and anesthesiologists.
In the case of tracheal resection and reconstruction, many scholars have made a lot of efforts to solve the ventilation problem after the trachea is cut during surgery. For example, when the trachea in the chest cavity is cut, a tracheal single-lumen tube is inserted from the surgical incision to the distal end of the trachea to maintain single-lung ventilation. This approach can solve the breathing problem during surgery, but the presence of the single-lumen tube in the surgical field greatly increases the difficulty of end-to-end anastomosis of the trachea and increases the risk of anastomotic leakage. At the same time, this method is more suitable for open surgery, but not for minimally invasive surgery, because it is inconvenient to place an endotracheal tube during minimally invasive thoracoscopic tracheal reconstruction, which usually requires additional surgical incisions or occupies part of the surgical channel [10]; To avoid the difficulty of suturing the anastomosis after intubation, some scholars have improved the above airway management, such as inserting a single-lumen tube at the distal end of the trachea to assist breathing, and then withdraw the tube and quickly perform an end-to-end anastomosis of the trachea when the arterial oxygen saturation (SaO2) is higher than 95%, and suspended the suturing process and reinserted the tube to maintain ventilation while the SaO2 is lower than 95% [11]. There are also reports of successful tracheal reconstruction surgery on patients with tracheal stenosis and tumor with the assistance of extracorporeal membrane oxygenation (ECMO) [12, 13]. The ECMO ensures the non-interference of the surgical field, but the risks of bleeding and coagulation must be taken into account and its high cost is also an issue that worth considering. The above maintenance of cross-field ventilation is performed under non-spontaneous breathing anesthesia.
There are also related reports on the use of spontaneous breathing for tracheal resection and reconstruction. Professor He employed laryngeal mask non-intubation anesthesia to perform thoracoscopic tracheal resection and reconstruction and carinal resection and reconstruction. This can avoid intubation in the cross field. There is no tube in the trachea, which allows a larger range of motion during resection and anastomosis of the trachea, and can also reduce the difficulty of end-to-end anastomosis of the trachea due to intubation [1]. Spontaneous-ventilation anesthesia is a relatively new type of anesthesia, which means that no mechanical ventilation is required during anesthesia, while the patient’s own respiratory function is retained to maintain ventilation and oxygenation during the operation. This can avoid endotracheal intubation and promote rapid recovery as patients wake up quickly without obvious throat discomfort after surgery. However, there are certain disadvantages of laryngeal mask spontaneous ventilation. Firstly, the laryngeal mask is easily displaced because it does not enter the airway, which will cause poor sealing, especially when the trachea is cut off, which will lead to insufficient ventilation. In this case, the single-lumen tube intubation is conducive to ensuring the patient’s ventilation volume and facilitating dual-channel oxygenation during surgery. Secondly, when performing surgery through the laryngeal mask, it may be difficult to place the suction tube when suction is required during the operation, and fiber bronchoscope guidance is required. These operations will also cause the laryngeal mask to shift. Besides, before using the laryngeal mask for spontaneous breathing, it is necessary to carefully select suitable patients, such as suitable for young patients with BMI < 30 and no difficult airway. Finally, there are also deficiencies in surgical safety. For example, emergency situations such as sudden bleeding, airway obstruction, and low oxygenation require emergency endotracheal intubation.
Maintaining ventilation and ensuring good oxygenation are the key to airway management during carina resection and reconstruction. Our patient had a history of right middle and lower lobectomy, with the right upper lobe and left lung remaining. The surgery requires resection of the carina and anastomosis of the proximal trachea to the left main bronchus. If only the upper lobe of the right lung is retained for single-leaf breathing under involuntary breathing anesthesia, the oxygen supply and CO2 excretion during the operation may not be sufficient. In addition, bilateral intrapulmonary intubation will affect the anastomosis of bilateral bronchial cuffs and the main bronchus. In order to solve the above problems, we abandoned the laryngeal mask mask, but used single-lumen tracheal intubation to retain spontaneous breathing anesthesia. During the operation, a small tube was inserted through a single-lumen tube to the distal end of the trachea to maintain the oxygen concentration and ventilation volume in the left lung. At the same time, oxygen supply in the single-lumen trachea through a ventilator can also ensure the oxygen concentration and oxygen flow of right lung ventilation to a certain extent. Oxygen supply through the patient’s spontaneous-ventilation and small tube can not only easily solve the patient’s ventilation and oxygenation problems during the operation, but also avoid the careful selection of suitable patients due to the use of laryngeal masks, so that the range of patients suitable for this anesthesia method is wider. Besides, compared with traditional endotracheal intubation, oxygen delivery by small tube can also reduce the difficulty of tracheal end-to-end anastomosis during surgery. In addition, the inserted small tube can also be temporarily connected to a sterile suction device to easily remove secretions and bloody fluids from the distal trachea to avoid airway obstruction. Finally, the insertion of a single-lumen tube can also respond quickly to emergencies during surgery.
Of course, since there have been reports of intrathoracic fires caused by electrocautery [14], we recommend that before inserting a small sterile endotracheal tube at the distal end of the trachea, sufficient hemostasis of the surrounding tissues is required to avoid fires in the surgical area due to excessive local oxygen concentration when electrocautery is used again. Of course, if you encounter a situation where you need to continue using electrocautery, you can suspend the introduction of pure oxygen, use a suction device to suck out the surrounding oxygen to reduce the oxygen content, and then perform electrocautery.

Conclusion
Robot-assisted single-lumen intubation with preserved spontaneous-ventilation combined with small-channel oxygenation is an alternative method for tracheal resection and reconstruction. Compared with traditional intubation methods, this technology is more conducive to the suturing of tracheal anastomosis during surgery, shortens the operation time, and promotes rapid postoperative recovery [15, 16]; compared with laryngeal mask spontaneous breathing anesthesia, it simplifies intraoperative respiratory management and can quickly deal with emergencies that may occur during surgery [17]. Although this method is currently employed to the carinal surgery in the patient with residual right upper lobe and left lobe, we believe that this technology will also be applicable to patients with more residual lung tissue or other airway resection and reconstruction. Of course, multiple centers are still needed to participate and include a large number of samples to determine the benefits this technology can bring to patients.

Supplementary Information