Thoracic surgery has evolved into minimally invasive surgery, in terms of not only surgical approach but also less aggressive anesthesia protocols and lung-sparing resections. Nonintubated anatomic segmentectomies are challenging procedures but can be safely performed if some essentials are considered. Strict selection criteria, previous experience in minor procedures, multidisciplinary cooperation, and the 4 cornerstones (deep sedation, regional analgesia, oxygenation support and vagal blockade) should be followed. Better outcomes in postoperative recovery, including resumption of oral intake, chest tube duration, and hospital stay, and low complication and conversion rates, are encouraging but should be checked in larger multicenter prospective randomized trials.
Key points
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Anatomic segmentectomies have become more frequent in the treatment not only of benign lesions and central metastasis but also in early-stage primary lung cancers.
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Nonintubated anatomic segmentectomies can be safely performed under deep sedation with vagal blockade in strictly selected patients.
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Improved postoperative recovery in terms of earlier resumption of oral intake, decreased chest tube duration, and hospital stay has been described.
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Nonintubated anatomic segmentectomy has an incidence of complications comparable with conventional intubation, and does not affect the quality of lymph node dissection in lung cancer.
Video content accompanies this article at http://www.thoracic.theclinics.com .
Introduction
Nonintubated anatomic resections under spontaneous breathing have spread widely within the last years, although they are not routinely performed in many thoracic surgery units. There are still many concerns about indications, technical details, and potential advantages and risks that should be first addressed.
The main challenges while facing major resections under spontaneous breathing are the need for a stable mediastinum, the control of cough reflex by vagal block, the balance of sedation, and the duration of the surgery to avoid respiratory depression and severe hypercapnia.
Anatomic segmentectomy has been considered for many years an alternative only for high-risk patients deemed inoperable for lobar resection because of decreased pulmonary function, because the idea of higher risk of recurrence has been well established since 1995. However, as minimally invasive thoracic surgery developed, the idea of lung-sparing resection became more interesting. Were all the cases of non–small cell lung cancer or other central lesions candidates for lobar resection, or could surgeons spare lung parenchyma in specific cases? Many studies proved that sublobar resections, especially anatomic segmentectomies, were oncologically optimal for some cases of early-stage lung cancer, and, as the knowledge and techniques evolved, these resections were extended to central benign lesions and metastases, as well as multicenter preinvasive or minimally invasive lesions or second primary tumors.
The combination of minimally invasive approach in terms of video-assisted techniques (video-assisted thoracoscopic surgery [VATS]), lung-sparing resections, and less aggressive anesthesia methods promises to be an attractive new approach in thoracic surgery: less invasive and more physiologic.
Anatomic segmentectomy
Sublobar anatomic resections include lung resections of segments and subsegments with division of both vascular and bronchial structures, and thus include anatomic segmentectomy. These procedures have especially spread within the last decade because of the diffusion and development of minimally invasive thoracic surgery, and the concept of lung-sparing surgery, which means safely preserving as much lung parenchyma as possible. A comprehensive knowledge is required of pulmonary anatomy in terms of intralobar segmental and subsegmental divisions, and the most frequent anatomic variations in arterial, venous, and bronchial division. There are not many reports that specifically analyze the anatomic patterns. ,
The main expected benefit is the preservation of more lung parenchyma, thus the absolute loss of postoperative lung function is lower than for lobar and supralobar resections. Most published studies have not addressed the functional repercussion, but an article by Charloux and Quoix in 2017 reported a lower decrease in postoperative forced expiratory volume in the first second (FEV1) at 12 months compared with lobectomy (5% vs 11%), a lower decrease in global pulmonary function in patients with diminished preoperative lung function, and a direct relation between the number of resected segments and the functional loss. Curiously, there are no studies that specifically address the reduction of lung function in relation to the surgical approach (VATS, open thoracotomy), and the loss of function within the early postoperative (first days or weeks) compared with lobar resections.
Anatomic segmentectomy has been used in the treatment of several disorders, mainly benign lesions centrally located in the lobe, pulmonary metastasis, and early-stage lung cancer. Since the Lung Cancer Study Group report in 1995, sublobar resections (anatomic and wedge) have shown a higher recurrence and death rate in tumors less than 3 cm in diameter, so lobectomy was set as the standard surgical treatment of early-stage lung cancer. Since then, there have been published many studies that prove that anatomic sublobar resections show the same disease-free and overall survival as lobectomy for tumors less than 2 cm, , , , so sublobar anatomic resections have been included in the main clinical guidelines as an accepted procedure for early-stage adenocarcinoma less than 2 cm, in peripheral locations without nodal involvement. ,
The available evidence points to equivalent outcomes in terms of survival, a lower rate of postoperative , and a better postoperative profile (chest tube duration, hospital stay). Nevertheless, it is necessary to highlight that most published studies are case series or comparative unicentric studies but there is still a lack of multicenter studies and randomized trials.
Nonintubated video-assisted thoracoscopic surgery
Benefits of Nonintubated Video-assisted Thoracoscopic Surgery
Despite the lack of comparative studies, thoracic surgery in awake patients has shown a decrease in overall postoperative stay and duration of chest tube compared with the traditional intubated approach. Likewise, a lower rate of postoperative complications has been reported in certain procedures, , and a cost reduction. Most noncomparative studies, such as case series or isolated case reports, show the feasibility of this approach for the management of most procedures in thoracic surgery. ,
As with awake nonintubated surgery, there are few randomized or comparative studies of nonintubated surgery in unawake patients. The results point to a decrease in the rate of postoperative complications, even in the case of anatomic pulmonary resections. A shorter anesthesia time, a higher occupational ratio in the operating room, a shorter postanesthetic recovery, and a shorter hospital stay have also been described. ,
Table 1 shows the main outcomes of nonintubated awake and unawake approaches in different types of pulmonary resections. , ,
| Procedure | Study | Author, Year | Main Benefits |
|---|---|---|---|
| Primary spontaneous pneumothorax | RCT | Pompeo et al, 2007 | Fewer side effects (vomiting, urinary retention) |
| Secondary spontaneous pneumothorax | PSM | Noda et al, 2012 | Lower postoperative respiratory complication rate |
| Lung volume reduction surgery | RCT | Pompeo et al, 2012 | Lower overall morbidity |
| Pulmonary metastasis | NRC | Pompeo et al, 2007 | Lower hospital stay |
| Minor VATS procedures | NRC | Irons et al, 2017 | Shorter anesthesia time, less postoperative moderate-severe pain |
| VATS lobectomies | NRC | Chen et al, 2011 | Less postoperative morbidity (lower complication rate) |
| Lung cancer in the elderly | NRC | Wu et al, 2013 | Lower postoperative delirium rate |
| Multiple indications | RCT | Liu et al, 2015 | Less postoperative morbidity (lower respiratory complication rate) |
| Pulmonary anatomic resections (segmentectomy and lobectomy) | PSM | Liu et al, 2016 | Earlier resumption of oral intake, less pleural fluid drainage, and shorter hospital stay |
Technical Aspects of Nonintubated Video-assisted Thoracoscopic Surgery
Sedation/general anesthesia
Anatomic segmentectomy under nonintubated VATS (unawake) requires deep sedation (Ramsay Sedation Scale >3) or even general anesthesia. By administering intravenous agents such as propofol (target-controlled infusion), the patient is maintained with a Bispectral Index (BIS) between 40 and 60, , although experienced groups recommend an even deeper anesthesia (BIS 30–50). By administering other agents, such as fentanyl, remifentanyl, sufentanil, or dexmedetomidine, the depth of sedation/anesthesia is kept constant. The main risk from deeper sedation is hypercapnia, which, if it exceeds the permissive limits (Pa co 2 >55 mm Hg), can increase the frequency and depth of breathing and the mediastinal balance, making the procedure difficult, as well as the risk of respiratory acidosis.
Locoregional analgesia
There are several ways to perform analgesia, with epidural analgesia, paravertebral block, and selective intercostal block being the most reported. Although it is not the subject of this article, some key concepts are highlighted.
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Epidural analgesia has been the gold standard for regional analgesia in nonintubated VATS. A somatosensory and motor block is performed, usually using drugs such as ropivacaine at different concentrations, or in combination with sufentanyl, with lidocaine and sufentanyl. Bupivacaine has also been used at different concentrations.
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Paravertebral blockade. As an alternative to epidural anesthesia, a paravertebral block/catheter may be performed. The paravertebral block is unilateral, produces no sympathetic block, and has a lower rate of respiratory complications, urinary retention, and hypotension. The use of ropivacaine has been described at different concentrations.
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Intercostal blockade. Selective intercostal block can be performed under direct view of the desired intercostal nerves with bupivacaine, and also percutaneously injected ropivacaine has been reported. The authors routinely perform intercostal blocks from the third to seventh intercostal posterior spaces, with bupivacaine 0.5%, 1 to 1.5 mL in each space at the beginning of the procedure, and at the end of the procedure; before closing the incision, we repeat the block, and sometimes extend it to the second intercostal space for relieving the pain occasioned by the tip of the chest tube ( [CR] ). Intercostal block is a more selective unilateral block, without systemic adverse events (urinary retention, constipation).
Oxygenation/respiratory support
Nonintubated VATS can be performed without the need for additional oxygenation, but oxygen supplementation through Venturi facial masks is commonly reported. , In addition, the use of conventional nasal prongs, high-flow oxygen delivery nasal prongs, and nasopharyngeal cannulas has also been described, in order to avoid hypoxemia during the procedure. These devices increase the fraction of oxygen in the inspired air to optimize oxygenation. Supraglottic devices such as the laryngeal mask have also been described. , , The aim is to keep a breathing rate of between 12 and 20 breaths per minute, to avoid tachypnea, which can lead to deeper breathing and an oscillating surgical field. With these devices, good tissue oxygenation is achieved and hypoxemia is avoided. The laryngeal mask allows for easier conversion to tracheal intubation in the event of an intraoperative complication. Fig. 1 summarizes some of the most frequently used devices for oxygenation.
Oxygenation can be ensured through these techniques, but the main concerns focus on the risk of hypercapnia. Secondary to rebreathing and deep sedation needed for anatomic resections, moderate hypercapnia is usually observed. In cases of severe hypercapnia, the authors reduce the propofol infusion and we assist the patient with the facial mask until recovering normal parameters, but, if severe hypercapnia remains, conversion to tracheal intubation and mechanical ventilation should be considered, especially in patients with some degree of pulmonary compromise.
Cough reflex: vagal block
Cough reflex during a nonintubated procedure can make it challenging to perform or even lead to a complication, so several methods have been used for its control (atropine in premedication, intravenous or aerosolized lidocaine), the most effective being direct vagal block with bupivacaine 0.5%, 2 to 3 mL in the low right paratracheal region or aortopulmonary window in procedures in the right and left hemithorax respectively ( [CR] ). Left vagal block is best performed by pulling the lung gently anteriorly and incising the mediastinal pleura just after the laryngeal recurrent nerve visualization. Vagal block ensures cough abolition for 12 hours so most anatomic resections can be safely performed. It is better to block the vagal transmission before initiating parenchyma or bronchial pulling maneuvers in order to avoid cough reflex triggering. It is mandatory for safely performing anatomic resections such as anatomic segmentectomies.
Anatomic segmentectomy in nonintubated video-assisted thoracoscopic surgery
Starting Point
Before embarking on a nonintubated program for anatomic segmentectomies, a learning curve for operating minor procedures is mandatory, in order to develop skills for all the members of the multidisciplinary team, and to achieve a comprehensive knowledge of the physiology of surgical pneumothorax in spontaneously breathing patients. Pulmonary biopsies, metastatectomies, and pneumothorax should first be attempted to find out the main difficulties and the possible solutions. , Patients with primary spontaneous pneumothorax are usually young and healthy patients with preserved cough reflex, so surgeons can safely manage the first attempts of vagal block and test the outcomes.
The VATS experience of the surgeon is relevant because nonintubated VATS anatomic segmentectomy defies the surgical capability to operate on a less stable mediastinal/surgical field. It is advisable to begin nonintubated major resections with highly experienced surgeons in VATS, able to manage intraoperative complications (ie, major bleedings) and complex procedures such as sleeve lobectomies in order to achieve abilities such as primary sutures for a potential bleed.
It is also recommended that anesthesiologists first develop a lateral decubitus orotracheal intubation learning curve and simulations of emergent intubation in an experimental model. The nursing team should be familiar with the essential details of the whole procedure and the management of critical potential situations. They must know their exact roles in the different steps of the procedure, and it is important to make them part of the successful development of these complex resections. The objective of these programs should focus on decreasing global invasiveness of the surgical procedure, preserving the safety, decreasing postoperative complications, and improving the antitumor immune profile.
Indications
Strictly selecting patients for nonintubated anatomic segmentectomy is extremely important, because these procedures combine both challenging surgical aspects with a complex environment, as described earlier.
Selection should be done in 2 steps: first, selecting cases for anatomic segmentectomy ( Box 1 ); second, selecting patients for nonintubated VATS.
Centrally located benign lesions
Carcinoid tumors
Pulmonary metastasis not amenable for wedge resection
Primary lung cancer
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Second primary lung cancer with past history of pulmonary resection
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Multiple multilobe pure GGO lesions (atypical adenomatous hyperplasia, AIS, MIA, lepidic predominant adenocarcinoma)
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Poor pulmonary reserve or other major comorbidity that contraindicates lobectomy
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Peripheral nodule less than or equal to 2 cm with at least 1 of the following:
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Pure AIS histology
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Nodule has greater than or equal to 50% ground-glass appearance on computed tomography
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Radiologic surveillance confirms a long doubling time (≥400 days)
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Peripheral tumors less than or equal to 2 cm in maximum diameter, without nodal involvement neither metastasis, regardless of histologic subtype and radiological appearance, with intraoperative lymph node assessment including intralobar N1 stations, and free resection margins of at least 1 cm or tumor diameter size
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Abbreviations: AIS, adenocarcinoma in situ; GGO, ground-glass opacity; MIA, minimally invasive adenocarcinoma.
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