Minimally invasive lung cancer surgery under spontaneous respiration: Is general anesthesia always required for lung surgery?

Introduction
A distinction is made between non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC), which also applies to progression and treatment. Most patients diagnosed with lung cancer are affected by a non-small cell tumor. Across all stages, the prognosis remains poor, with an expected 5-year survival rate of around 20% for women and 15% for men, and surgical removal still offers the best chance of cure for early-stage non-small cell lung cancer (NSCLC).

Video-assisted thoracic surgery, VATS
In recent years, minimally invasive lung surgery (video-assisted thoracic surgery, VATS) has established itself internationally as a standard procedure, despite initial skepticism, and is also becoming increasingly important in Germany. Since Giancarlo Roviario first described a complete lung lobectomy using a minimally invasive technique ("VATS lobectomy") in the early 1990s, the procedure has been continuously developed over the past decades. Supposed arguments against video-assisted oncological operations on the lung, such as a possible suboptimal overview during the procedure or concerns regarding the necessary radicality, have been refuted by a large number of clinical studies. From an oncological point of view, this surgical procedure is now considered to be on a par with classic "open" techniques and also offers relevant advantages for patients in the post-operative phase. Patients undergoing VATS lobectomy not only experience significantly less pain, but also suffer less frequently from atrial fibrillation, atelectasis, air leaks and pneumonia, which results in shorter hospital stays.

Oncological lung surgery under spontaneous respiration
At the same time, it is now possible to completely dispense with intubation and mechanical ventilation in selected patients with impaired lung function and thus perform an anatomical lung resection under spontaneous respiration ("ni-VATS", non-intubated VATS). This avoids the described disadvantages such as the release of proinflammatory cytokines, mechanical damage at the alveolar level due to barotrauma and atelectasis of the dependent lung, e.g. due to the administration of muscle relaxants.
In 2014, Diego Rivas reported on the performance of the first uniportal niVATS, in which the entire intervention was performed via a single approx. 3 cm long incision ("uniportal") under local anesthesia. We performed the first niVATS lobectomies in Germany at Hannover Medical School in 2018. In the past two years, a total of over 30 scientific papers have been published on this topic.
Asian working groups, particularly those led by Jin-Shing Chen from Taiwan, are leading the way in this surgical technique with impressive case numbers. Nevertheless, the minimally invasive procedure is still used far too rarely globally.

There is a tendency for niVATS lobectomies to be superior to open surgical procedures in terms of length of hospital stay, duration of surgery, drainage times, complications and mortality, but there is still a lack of reliable scientific data.
There is a great deal of acceptance for the performance of minor procedures under spontaneous breathing, while actual anatomical lung resection in this form is currently only performed at a few centers.
Fortunately, a recent survey of German thoracic surgery clinics shows that niVATS is already being practiced and offered to patients at various locations in Germany. A total of 32 Clinical Departments regularly perform niVATS procedures, and in 3 clinics
even lobectomies are performed regularly.

Nevertheless, despite a general interest in the procedure, there is still an immense need for education. Our clinical experience over the last two years with numerous niVATS procedures and 8 masterclass courses with live operations on site proves that niVATS programs can be established with acceptable effort after
appropriate coaching. The feedback received confirms that participants experienced in minimally invasive surgical procedures were able to start with smaller niVATS procedures in order to perform complex resections in the meantime. The key to success is the simultaneous coaching of anesthesiologists and surgeons, who are formed into a well-coordinated unit.

Anatomical lung resection under spontaneous breathing - technical implementation
As mentioned above, this surgical technique is currently still reserved for specialized centers with particular expertise. Dispensing with a classic intubation anaesthetic inevitably leads to unwanted patient movements. Coughing due to intraoperative traction on the airways, diaphragmatic excursions and mediastinal shift are not suppressed, unlike under general anesthesia. This increases the demands on the surgeon and anesthetist alike, which requires regular Communications, including "understanding without words". Only through optimal and targeted surgical preparation can these procedures be performed with the necessary high level of patient safety.

Preoperative phase
Our current concept involves the preoperative inhalation of lidocaine to suppress a possible cough (30 minutes before the operation) before either a thoracic epidural catheter or an alternative regional procedure (erector spinae block, paravertebral block, catheter placement if necessary) is inserted under sonographic control. After placing the patient in the classic lateral position, we perform extensive local anesthesia in the 4th intercostal space (surgical access) before washing the surgical field with sterile solution. This ensures that the required exposure time for the local anaesthetic is always observed. Bladder catheters, arterial blood pressure measurements and central indwelling catheters are not required at all. Only the non-invasive measurement of oxygen saturation and blood pressure as well as an ECG lead are performed.

Intraoperative phase
During the procedure, the patient receives analgosedation with titrated administration of dexmedetomidine (sedative) and a short-acting opiate. Dexmedetomidine is a selective alpha-2 receptor agonist with sedative, analgesic, sympatholytic and
muscle-relaxing properties, which allows a depth of sedation that still allows the patient to be awakened by verbal stimulation. Supplemented by the targeted use of an opioid, excellent analgosedation is achieved, which is very suitable for this type of intervention. Under spontaneous respiration and oxygen insufflation, an approx. 3 cm long incision is then made at the level of the 4th intercostal space and the 10 mm/ 30° optic is inserted via an inserted soft tissue retractor. As the optics must also be inserted via the single access point, this retractor ensures optimal viewing conditions by reliably preventing smearing through the subcutaneous fatty tissue. A selective blockade of the vagus nerve under direct vision in the paratracheal area is crucial for the success of the operation, as this allows the cough stimulus to be suppressed for the duration of the intervention.
In addition to the surgeon's expertise, modern equipment is essential for this special surgical procedure. For this technique, we use special surgical instruments, high-resolution optics and the latest generation of 7 mm endo-staplers with precision tips and regular ultrasonic instruments, such as the Harmonic HD-1000i (Ethicon ®), to enable fast and clean preparation. As with conventional VATS, the procedure itself is carried out by dissecting the relevant anatomical structures (bronchi, vessels),
which are gradually removed using the appropriate instrument. At the end of the procedure, the part of the lung to be removed along with the associated lymph nodes is removed from the chest using a tear-resistant salvage bag and sent for histological examination. We
usually place a pleural drain at the end of the operation, although this can be omitted in individual cases ("tubeless VATS").

Postoperative phase
By avoiding general anesthesia and using a suitable regional procedure, patients are awake and pain-free at the end of the procedure, so that they are only taken to the recovery room for a short monitoring phase. After a morning operation, the patient can usually eat their first meal and take their first steps in the afternoon. The average postoperative stay in the hospital is around 3 days; general patient satisfaction after treatment is high.

Conclusion
Minimally invasive surgical procedures have become an integral part of modern lung surgery. As a logical further development of this concept, niVATS enables patients with impaired lung function or advanced age in particular to undergo an often curative operation that would otherwise be denied to this patient group. niVATS requires special expertise from surgeons and anaesthetists and is therefore still reserved for only a few centers in Germany.