SV-VATS exhibits dual intraoperative and postoperative advantages

Introduction

In recent years, with the promotion of the concept of Enhanced Recovery after Surgery (ERAS) (1), video-assisted thoracic surgery (VATS) has been developed rapidly, which has resulted in the emergence of spontaneous ventilation VATS (SV-VATS). Aided by artificial pneumothorax, SV-VATS is able to be performed successfully while avoiding the tracheal injury caused by endotracheal intubation, and also reduces the use of neuromuscular blocking agents (NMBAs). There have been extensive reports on the applications of SV-VATS for treating pulmonary nodules (2,3), hemangiomatosis (4), tracheal stenosis (5) and pulmonary bullae (6). Xun et al. reported that SV-VATS involved shorter operative time, shorter hospital stay, fewer postoperative complications, a shorter hospital stay, and improved the entire postoperative recovery compared to mechanical ventilation VATS (MV-VATS) (7). However, whether SV-VATS could become a first-choice option for thoracic surgeons remains debatable. Our team conducted a retrospectively controlled trial at the First People’s Hospital of Yunnan Province, in order to evaluate the universality and perioperative advantages of SV-VATS systematically. We present the following article in accordance with the STROBE reporting checklist (available at https://dx.doi.org/10.21037/atm-21-2297).

Methods

Data source

Comparative surgical trials between SV-VATS and MV-VATS were conducted from March of 2015 to October of 2020 at the First Affiliated Hospital of Yunnan Province. We collated information of patients receiving VATS which performed by our clinical team for treating either pulmonary or non-pulmonary diseases. In total, approximately 450 patients were recruited with their clinical data during the entire hospitalization, and ethical approval for the trial was granted by the Ethics Review Committee of the First People’s Hospital of Yunnan Province. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). Also, written informed consent was obtained from all patients for participation in the trial. After filtering out cases refer to the exclusion criteria, a total of 244 cases (including 124 patients who underwent SV-VATS and 120 patients who underwent MV-VATS) were included in the formal data analyses of this study, as explained below. Overall, the first 2–3 years of the trial were spent on devising the standard procedures for database design.

Exclusion criteria

• Patients with incomplete data or obvious logical errors;
• One case that was transferred to a thoracotomy;
• No unplanned reoperation was included;
• Those with severe postoperative complications, including postoperative high fever, long postoperative drainage duration, and purulent thoracic drainage.

Procedures

The surgical procedure in the SV-group was performed as follows: In addition to normal general anesthesia, anesthesia of SV-VATS was combined with epidural anesthesia, vagus nerve block, intercostal nerve block, and local anesthesia on the surface of the lung. It is designed to reduce intraoperative lung sensitivity to traction and further reduce the use of opioids. Prior to induction of general anesthesia, an epidural anesthesia was performed at the level of the fourth thoracic vertebra, and Ropivacaine (7.5 mg/mL) 21 mL was injected. This period usually cost anesthetics an extra 15–30 min compared with MV-VATS. Then intravenous channels were established and intravenous administration of Etomidate 0.3 mg/kg + Midazolam 0.1 mg/kg + Dexamethasone 10 mg + atropine 0.5 mg was given. An intravenous pump (Smiths Medical Co., Ltd., Hangzhou, Zhejiang Province, China) with Propofol+ Remifentanil was then used to maintain anesthesia (the dose of remifentanil is usually half that of MV-VATS), meanwhile a laryngeal mask (Single cavity of common type, 4.0#, Jian qi Medical Equipment Co., Ltd., Chang yuan, Henan Province, China) was placed to maintain a 30–40% oxygen concentration and preserve spontaneous breathing. After opening the chest, the surgeon completed the vagus nerve block and intercostal nerve block with Ropivacaine (7.5 mg/mL) 14 mL and Lidocaine (0.2 mg/mL) 10 mL. Then Lidocaine (0.2 mg/mL) 10 mL was applied to the surface of the lung, and the operation was started after the lung collapsed. In cases of poor intraoperative lung tissue collapse and poor visual field, high frequency neap tidal ventilation or suspension of ventilation should be performed to continue the surgery. The thoracic cavity was explored, the free target domain was dissected, and the resection was performed with an endoscopic cleavage closure device (Victormedic Medical and Surgical Instruments Co., Ltd., Changzhou, Jiangsu Province, China). Surrounding lymph nodes were dissected by intraoperative observation of the resected lung tissue or by reference to intraoperative frozen pathology. Following the operation, normal saline was infused into the thoracic cavity. After the lung enlargement test confirmed that there was no air leakage at the broken end of the bronchus, the thoracic drainage tube (Jiangsu Yu bang Medical Equipment Technology Co., Ltd., Taizhou, Jiangsu, China) was indwelt into the operation hole, and the thoracic cavity was closed. In the early postoperative period, getting out of bed, eating, and drinking water were encouraged.

The surgical procedure in the MV-group was performed as follows: Firstly, intravenous channels were established and the same intravenous administration of Etomidate 0.3 mg/kg + Midazolam 0.1 mg/kg + Dexamethasone 10 mg + atropine 0.5 mg was given. An intravenous pump with Propofol+ Remifentanil was then used to maintain anesthesia, meanwhile MV endotracheal intubation was performed, adjusting the oxygen concentration to control blood oxygen saturation at 97–100%. The surgical methods were the same as those in the SV group. After 6 h of observation, the patients were encouraged to get out of bed and consume food and water.

Gathering indicators

The operative data (operation time, intraoperative bleeding volume and types of surgeries), postoperative thoracic drainage (duration of thoracic drainage, total drainage volume, daily average drainage volume and drainage peak), perioperative laboratory indexes, perioperative X-ray expressions, postoperative complications and hospitalization-cost (economic and time costs) of the two groups undergoing different procedures were collected. We did no effort to address potential sources of bias.

Initially, we collected postoperative drainage data and operation data including operation time, intraoperative bleeding, and types of surgeries. We found a significant reduction in postoperative drainage with SV-VATS, but as shown as the results of multiple linear regression analysis for intraoperative indicators and postoperative thoracic drainage, the reduction in intraoperative blood loss is not sufficient to fully explain the advantage of SV-VATS in reducing postoperative effusion. Therefore, we then collected our patients' laboratory indexes related to inflammation (preoperative laboratory blood exploration being done within a week before surgery; postoperative laboratory blood exploration being done on the postoperative day 2) and X-ray expressions perioperatively (preoperative laboratory blood exploration being done within two weeks before surgery; postoperative laboratory blood exploration being done on the postoperative day 1),and compared postoperative indicators and changes in these indicators before and after surgery. All of these inflammation-related indicators suggest a significant perioperative advantage of SV-VATS. Subsequently, we further expanded the observation indexes and summarized the postoperative complications of the patients from the end of surgery to discharge. At last, the time cost and economic cost of patients receiving SV-VATS and MV-VATS were also summarized and compared.

Statistical analysis

U-test was used to compare the SV-VATS and MV-VATS in terms of operation indicators, postoperative thoracic drainage, laboratory indexes and cost. Results of postoperative X-ray expressions and complications were analyzed with chi-square test, and we performed a multiple linear regression for intraoperative indicators and postoperative thoracic drainage.

Results

About 450 patients were included and 244 were included refer to the exclusion criteria. No loss to follow-up. The two groups exhibited no significant differences in either sex [SV-group (female 66, male 58), MV-group (female 64, male 56), Pearson χ²=0.987] or age (SV-group 50.1±14.2 years old, MV-group 51.4±12.1 years old, P value =0.600) distribution. There were 4 cases missing the data of laboratory indexes and X-ray images: the patients were transferred to our hospital for advanced treatment, and the data of preoperative laboratory indexes and X-ray images were not collected in our hospital.

Intraoperatively, there were no significant differences between the SV- and MV-groups in terms of operation time (SV-group 118.7±50.5 min, MV-group 133.3±57.2 min, P=0.581). However, the SV-group exhibited a markedly lower intraoperative bleeding volume (SV-group 41.4±34.7 mL, MV-group 78.2±83.1 mL, P<0.001) (Table 1). The majority types of surgeries in two groups were both resection of pulmonary nodules. Other surgeries were also completed successfully in two groups (Table 2).

Table 1 Results of the significance test (U-test) for comparing SV-VATS and MV-VATS in terms of operation time and intraoperative bleeding volume
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Table 2 Summary of the types of surgeries of SV-VATS and MV-VATS
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SV-VATS showed advantages in reducing postoperative thoracic drainage (total drainage volume [SV-group 394.7±348.0 mL, MV-group 569.6±423.5 mL, P<0.001]; daily average drainage volume [SV-group 117.5±74.9 mL, MV-group 146.9±77.7 mL, P=0.001]; and drainage peak [SV-group 199.1±146.1 mL, MV-group 242.1±140.2 mL, P=0.003], while simultaneously shortening the duration of thoracic drainage (SV-group 3.1±1.4 d, MV-group 3.6±1.4 d, P=0.001) (Table 3).

Table 3 Results of the significant test (U-test) for comparing SV-VATS and MV-VATS in terms of thoracic drainage
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In order to assess the influence of intraoperative indicators on postoperative thoracic drainage, we performed a multiple linear regression analysis. The operation time and intraoperative bleeding was significantly correlated with the volume of total postoperative drainage, average daily drainage, and drainage peak. However, intraoperative bleeding seemed to exert a greater impact on postoperative drainage than the duration of surgery, as its standardized beta was notably higher. According to the unsatisfactory R-square of each regression model (0.494, 0.510, 0.480, respectively), more indicators was required for precise regression model. In other words, other factors of peri-operation should influence postoperative drainage (Table 4).

Table 4 Results of the multiple linear regression analysis for intraoperative indicators and postoperative thoracic drainage
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No difference shown in preoperative laboratory indexes between the two groups, however, patients in the SV-group had significantly lower postoperative weight blood cells (WBC, SV-group 8.1±2.3 10⁹/L, MV-group 10.5±3.8 10⁹/L,P<0.001), NEUT (neutrophils ratio, SV-group 70.8%±7.1%, MV-group 77.9%±8.9%, P<0.001), and serum albumin concentration (SV-group 33.6±3.2 g/L, MV-group 35.1±3.4 g/L, P=0.001) than patients in the MV-group after operation. This change is more directly reflected in the calculation of variations of WBC (SV-group 1.6±3.0 10⁹/L,MV-group 4.1±3.7 10⁹/L, P<0.001), NEUT (neutrophils ratio, SV-group 8.7%±10.6%, MV-group 16.8%±12.1%, P<0.001), and serum albumin concentration (SV-group −7.6±4.0 g/L, MV-group −5.7±4.1 g/L, P=0.001) after surgery (Table 5). As to the postoperative X-ray expressions, there was little significant difference between the two groups, while SV-group suggested less risk of moderate or more pleural effusion [SV-group 3 (total 119), MV-group 13 (total 121), P=0.011] (Table 6).

Table 5 Results of the significant test (U-test) for comparing SV-VATS and MV-VATS in terms of laboratory indexes of inflammation and nutrition
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Table 6 Results of the significance test (chi-square test) for comparing SV-VATS and MV-VATS in terms of postoperative X-ray expressions
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SV-VATS also has an advantage over MV-VATS in reducing the short-term risk of postoperative complications. As mentioned above, the SV-group had a significantly reduced risk of postoperative inflammatory reaction and large postoperative thoracic effusion. On the other hand, the risk of postoperative malignant arrhythmias [SV-group 4 (total 119), MV-group 14 (total 121), P=0.016] and constipation after surgery [SV-group 23 (total 119), MV-group 38 (total 121), P=0.032] is significantly reduced, possibly due to restricted intraoperative opioid use and preservation of spontaneous breathing (Table 7).

Table 7 Results of the significant test (chi-square test) for comparing SV-VATS and MV-VATS in terms of postoperative complications
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All of the above results suggest that SV-VATS can provide good intraoperative lung protection and reduce the subjective uncomforted feeling and objective cost of postoperative recovery. Considering the influence of other factors in the clinical work, we did not directly observe the reduction of postoperative hospital stay (SV-group 6.6±2.0 d, MV-group 6.1±2.0 d, P=0.087) in the SV group. However, the shortened drainage time and the reduction of hospitalization cost (SV-group 31,858.9±11,574.5 yuan, MV-group 38,527.6±13,205.1 yuan, P<0.001) all suggest the potential of SV-VATS to accelerate postoperative recovery (Table 8).

Table 8 Results of the significant test (U-test) for comparing SV-VATS and MV-VATS in terms of economic and time costs
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Discussion

Thoracic surgeons have never stopped their search for improvements to VATS, leading to advanced devices or techniques such as harmonic scalpel (8), uniportal VATS (9), and robotic thoracic surgery (10). With the emergency of SV-VATS, more and more thoracic surgeons began to try this new surgical mode, and the feasibility and advantages of the relevant studies are not rare. Wen et al. conducted a meta-analysis of 27 studies on SV-VATS and concluded that the advantages of SV-VATS in reducing postoperative complications and accelerating postoperative recovery compared to traditional MV-VATS (11). A meta-analysis of 14 RCTs of two VATS modes reported that SV-VATS reduced postoperative hospital stay and patients' subjective discomfort after surgery (12). A meta-analysis involving more than 1,600 patients reached similar conclusions (13).Overall, SV-VATS has shown unique advantages in both mediastinum (14) and pulmonary surgery (15). However, these studies were limited to evaluating hospital stay, thoracic drainage time, postoperative complications and other outcomes, lack of exploration of the factors that contribute to these outcomes. By the collection of preoperative and postoperative laboratory indexes and imaging data, this study found the objective evidence that SV-VATS reduced the inflammatory response caused by surgery and the risk of moderator or more thoracic effusion. We also preliminarily analyzed the possible relationship between these objective indicators and postoperative thoracic drainage and postoperative short-term complications. The next step for our team is to explore the underlying mechanisms of these connections.

In this study, we found that the operation time was not significantly different between the SV- and MV-groups (SV-VATS 118.7±50.5 min, MV-VATS 133.3±57.2 min, P>0.05). Although the pulmonary activity generated by spontaneous respiration was present throughout the operation, intraoperative bleeding in SV-VATS tended to decrease (SV-VATS 41.4±34.7 mL, MV-VATS 78.2±83.1 mL,P<0.001). SV-VATS is not only suitable for resection of pulmonary nodules. In fact, we have successfully performed several types of thoracic surgery, including resection of mediastinal masses, LVRS and etc. with spontaneous ventilation. Especially, a 71-year-old patient accepted the resection of trachea-cystectomy in SV-group. The surgery was successful, with less than 50ml of intraoperative bleeding. No postoperative complication was monitored expect of the constipation. After symptomatic treatment, the patient defecated normally and went back home to recuperate on the postoperative day 5. In our view, limiting the use of anesthetics might be one of the reasons of this phenomenon. Considering that anesthetics promote the formation of microcirculation congestion in the lung, the intraoperative bleeding in SV-VATS procedures was considerably less than that of MV-VATS, despite the plentiful use of anesthetics during dissection and devascularization. In short, SV-VATS exhibited a similar operation time to that of MV-VATS, while at the same time promoting reduced intraoperative bleeding.

Among factors used to evaluate postoperative recovery, thoracic drainage in SV-VATS exhibited the most beneficial effect. SV-VATS showed advantages in reducing postoperative thoracic drainage [total drainage volume (SV-group 394.7±348.0 mL, MV-group 569.6±423.5 mL,P<0.001); daily average drainage volume (SV-group 117.5±74.9 mL, MV-group 146.9±77.7 mL, P=0.001), and drainage peak (SV-group 199.1±146.1 mL, MV-group 242.1±140.2 mL, P=0.003)], while simultaneously shortening the duration of thoracic drainage (SV-group 3.1±1.4 d, MV-group 3.6±1.4 d, P=0.001). By restoring the loss of fluid from the patient’s body and alleviating their worries regarding postoperative recovery, SV-VATS improved patients’ surgical experiences and accelerated postoperative recovery. The reduction of thoracic drainage, either the duration or volume, directly explains why numerous studies have claimed that SV-VATS can significantly shorten postoperative hospital stay (16,17). As the primary way of discharging lung tissue exudate, the reduction of thoracic drainage can reduce the loss of albumin and glucose. Good postoperative nutritional status is conducive to tissue healing and functional recovery of patients, and the dynamic balance of body fluids directly affects blood pressure, metabolism, and many other aspects.

Multiple linear regression analysis showed that operation time and intraoperative bleeding dramatically influenced postoperative thoracic drainage. However, interestingly, the unsatisfactory R-square of the model suggested that other factors are linked to postoperative thoracic drainage. Due to interest in factors which influence postoperative drainage, we analyzed preoperative and postoperative laboratory indexes and X-ray expressions of patients. Patients who received SV-VATS had less proliferation of WBC and NEUT after surgery, suggesting that SV-VATS induced less inflammatory response in the body. The proliferation of wight blood cells and neutrophils is regulated by cytokines and is closely related to the activation degree of the body’s inflammatory system (18). With regard to changes in serum albumin, we did not find an explanation for the low postoperative serum albumin concentration in patients with SV-VATS. However, serum albumin concentration played an important role in maintaining plasma osmotic pressure. In combination with the results in Table 3, patients who received SV-VATS showed less exudation despite low postoperative serum albumin, indirectly reflecting the inhibitory effect of SV-VATS on postoperative exudation. As to the postoperative X-ray expressions, SV-group suggested less risk of moderate or more pleural effusion. It was consistent with the reduced pleural and pulmonary exudation shown by thoracic drainage.

From the patient’s perspective, the most intuitive result of SV-VATS was the reduction of short-term postoperative complications and the reduction of hospitalization costs. Smooth recovery process can effectively relieve the anxiety of patients after surgery. At the same time, the reduction of the overall economic cost of treatment not only improved the postoperative satisfaction of patients, but also brought the hope of surgical treatment for patients with financial constraints. In order to give full play to the advantages of postoperative recovery from SV-VATS, we required patients to receive preoperative education to help them overcome their fear of getting out of bed, eating and drinking water in the early post-operative period. Our nurses would also aid the patient to get out of bed early and resume eating and drinking water after surgery. There was no specific consideration for patients receiving SV-VATS additionally.

SV-VATS exhibits dual intraoperative and postoperative advantages. Unfortunately, we only retrospectively collected case data from our only medical group in recent years, in order to avoid the influence of different surgical skills of different surgeons on the experimental results. Therefore, this study has a limited sample size and is limited to a single-center retrospective study. We will continue to promote and research SV-VATS in the future, and look forward to cooperating with other clinical centers.

Conclusions

SV-VATS is suitable for various types of thoracic surgery, and effectively reduce intraoperative bleeding and postoperative thoracic drainage. With less postoperative inflammatory response, it reduces the risk of short-term postoperative complications. It is also able to help to reduce the financial burden of patients.SV-VATS has a promising future, and we hope that more thoracic surgeons will work together to accelerate the maturity and promotion of this technology.

Acknowledgments

Funding: Science and Technology Program of Yunnan Province (2018NS0272).

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://dx.doi.org/10.21037/atm-21-2297

Data Sharing Statement: Available at https://dx.doi.org/10.21037/atm-21-2297

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://dx.doi.org/10.21037/atm-21-2297). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Ethical approval for the trial was granted by the Ethics Review Committee of the First People’s Hospital of Yunnan Province. Also, written informed consent was obtained from all patients for participation in the trial. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013).

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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