With a combination of subxiphoid-subcostal access and non-intubated anesthesia with mechanically controlled ventilation under LMA management, our study showed that NI-STT was safe and feasible and resulted in excellent perioperative outcomes and short hospital stays. Thoracoscopic surgery without endotracheal intubation avoids intubation-related complications, leading to relief of symptoms, a lower rate of complications and a fast recovery.
Over the past several decades, various surgical techniques have been advocated for thymectomy in treating anterior mediastinal tumors and MG. Although trans-sternal surgery remains the gold standard of thymectomy, with the improvements of thoracoscopic instruments and techniques, VTAS surgery has been an alternative to thymectomy1–2. There are different approaches to VATS thymectomy, which includes the unilateral, bilateral, transcervical, robotic, subxiphoid or combination approach, and the main choice is the lateral approach13,14. Although there were efforts to reach a consensus regarding the standard VATS thymectomy, but no consensus has been available now14. The choice of surgical approach is usually based on the experience and preference of the surgeon. However, the lateral VATS approach is associated with difficulties in identifying the contralateral phrenic nerve, narrow operative field in neck region and persistent intercostal nerve paralysis or neuralgia15. Hence, in recent years, Hsu et al.16 and Suda et al.4,5,15 previously reported a thoracoscopic thymectomy via the subxiphoid approach without any intercostal incision, which has several advantages4,5,12,15,16. First, the excellent surgical field from subxiphoid approach is similar to the view of median sternotomy and helps confirm the superior poles of thymus and bilateral phrenic nerves. The adequate visualization allows the maximum resection of thymus and surrounding fat tissues, reducing the chance of accidental blood vessels or phrenic nerve injury. Second, with the help of artificial pneumothorax created by CO2 insufflation instead of lifting of the sternum, the mediastinum is compressed and the bilaterally ventilated lungs are shifted away, greatly providing the operative vision and allowing for safer dissection. In our experience, low pressure CO2 insufflation into the mediastinum does not cause the changes in hemodynamic status of the patients. In addition, subxiphoid approach thymectomy does not cause intercostal nerve injury by avoiding any intercostal incision. Therefore, the postoperative pain was significantly relieved, and there was no abnormal chest wall paresthesia in the study. Less pains mean less usage of analgesics. Also, there is no visible scar in the neck and upper chest area, which is also a clear cosmetic advantage. Furtherly, in our experiences, subxiphoid VATS thymectomy has short drainage duration, postoperative hospital stays and low hospitalization expenses, comparable to other studies15,17.
Double-lumen intubation and single-lung ventilation general anesthesia technique were needed for conventional thoracoscopic surgery, which met the need of intraoperative lung ventilation and provided the surgeon with a broad surgical field. However, many complications are caused by intubation and extubation procedures, such as airway trauma, residual neuromuscular blockade, and ventilator-induced lung injury. To overcome the complications associated with endotracheal intubation, non-intubated VATS was recently described in selected patients with thoracic disease, including pulmonary and mediastinal diseases, and even minimally invasive esophagectomy and pleural empyema7–11,18−22. Non-intubated anesthesia may avoid the potential complications that the intubation may result in, and may be helpful to judge the reason of postoperative irritable cough, sore throat, and hoarseness. One major concern about using the non-intubated anesthesia for VATS thymectomy was how respiratory function is maintained in a patient with an artificial pneumothorax under the management of LMA. To prevent respiratory failure, we selected patients with good cardiopulmonary function for this study. Only one patient developed persistent hypoxia and was converted to intubated general anesthesia finally. In most of the non-intubated patients, SpO2 was satisfactorily maintained above 90% during the whole operation. Nonetheless, patients with poor cardiopulmonary function should be carefully examined and selected before attempting this procedure.
The other major concern is whether it is feasible and safe to perform a surgical procedure during non-intubated thoracoscopic thymectomy. Dissection of blood vessels, and bilateral phrenic nerves are more technically demanding because of the diaphragmatic movement during spontaneous breathing, especially when the respiratory rate was more than 20 breaths per minute. The surgeons must adjust the instruments according to the rhythm of the breathing and diaphragm movement to make a precise dissection, just like beating heart coronary bypass surgery. We performed the NI-STT since 2016. In our experiences, the diaphragmatic movement during spontaneous breathing would interfere with the surgical procedures, resulting in an increase in the difficulty of the operation and a prolonged learning curve. Therefore, in our patient cohort, we tried to preform NI-STT without spontaneous breathing under LMA management. The use of muscle relaxants inhibited the movement of diaphragm and spontaneous breathing, so that it did not interfere with surgical procedures. Besides, additional intrathoracic vagal blockade was not required to abolish the cough reflex by using the muscle relaxants during non-intubated thymectomy in our study group22. Finally, epidural anesthesia or paravertebral block was used traditionally for non-intubated spontaneous ventilation anesthesia, however, it may lead to side effects such as hypotension, bradycardia, urinary retention, epidural hematoma, or infection. In this present study, Intercostal nerve block and rectus abdominis sheath block were performed with 0.4% ropivacaine instead of epidural anesthesia or paravertebral block. And the results revealed that postoperative pain was mild in almost all cases, indicating that local anesthesia was also feasible and effective in this procedure.
However, the NI-STT also has disadvantages. Even with the presence of artificial pneumothorax, an excessively high BMI would lead to a narrow surgical field and further make surgery difficult. In addition, for patients with tumors invading surrounding organs or large vessels, this method may be not suitable, and open surgery should be recommended. In addition, we acknowledged that the present study was limited by its single-center retrospective nature and a small number of patients, and thus, intrinsic bias may exist. Besides, the lack of a control group who received endotracheal intubated anesthesia makes it difficult to confirm the specific benefits of NI-STT. However, the low conversion rate of non-intubated to intubated anesthesia and low complication incidence indicate that NI-STT could be safely performed in selected patients. Further research is encouraged to clarify the applicability and benefits of NI-STT for specific patient groups.