Lung cancer is the fastest-growing malignancy worldwide in morbidity and mortality, the most common cause of cancer death in men and the second leading cause of cancer death in women (1). Due to the popularization of low-dose computed tomography (CT) screening, the rate of detection of small pulmonary nodules (especially ground-glass nodules) has significantly increased in recent years, which makes early diagnosis and treatment of lung cancer more challenging (2, 3). With the rapid development of minimally invasive techniques, traditional thoracotomy has been transformed into video-assisted thoracoscopic surgery (VATS) with less risk to patients (4, 5). In general, a chest tube is routinely placed in the pleural cavity to mitigate against possible air leaks, hemorrhage, and chylothorax after VATS (6). However, some side effects of chest tube insertion are still difficult to avoid, such as increased postoperative pain and hindrance to postoperative activity, which could impede patient functional rehabilitation and significantly prolong postoperative length of stay (LOS) (7, 8).

Enhanced recovery after surgery (ERAS) is a multimodal perioperative management strategy first proposed by Dr. Engelman in 1994 in order to reduce postoperative pain, promote patients’ recovery, reduce the cost of hospitalization, and shorten the length of hospital stay (9). In recent years, this multidisciplinary perioperative rehabilitation concept has been widely applied in thoracic surgery with satisfactory results (10). An increasing number of thoracic surgeons, in order to promote the idea of ERAS, have attempted to apply no routine chest tube drainage (NT) strategy after thoracoscopic lung resection (11, 12). However, the increased incidence of postoperative pneumothorax and poor recruitment of the lungs are the main issues caused by the NT strategy (13).

Although several centers have conducted studies to explore the effect of NT strategy for thoracoscopic pulmonary resection in recent years, the safety and feasibility of not routinely placing a chest tube after lung resection remain controversial. A meta-analysis performed by Li et al. (14), including 6 retrospective and 3 prospective cohort studies, demonstrated that it was feasible and safe to omit chest tube after VATS for carefully selected patients. However, inappropriate inclusion criteria and relatively small sample sizes may introduce considerable bias, thereby reducing the reliability of the results. In addition, the perioperative outcomes that they reported were not comprehensive enough. To arrive at a more substantial conclusion, we aimed to conduct a systematic review and meta-analysis to determine the effect of NT strategy after thoracoscopic pulmonary resection on perioperative outcomes.

This systematic review and meta-analysis was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) guidelines and statement (15, 16). The protocol of this systematic review and meta-analysis has been registered on the INPLASY website (https://inplasy.com/inplasy-2022-4-0026); the registration number is INPLASY202240026.

The placement of routine chest tube drainage after thoracoscopic pulmonary resection has already been the gold standard approach to prevent postoperative pneumothorax and pleural effusion (33). In recent years, an increasing number of thoracic surgeons, in order to realize the concept of ERAS, have attempted to not routinely place chest tube drainage and instead use the method of prophylactic air-extraction catheter insertion procedure or complete omission of chest tube drainage (21, 32). However, the safety and feasibility of not routinely placing a chest tube after lung resection remain controversial. To date, no meta-analysis has been conducted to comprehensively compare the perioperative outcomes between with and without routine chest tube drainage after video-assisted thoracoscopic pulmonary resection. Therefore, we performed a systematic review and meta-analysis including 12 comparative studies on this subject to further identify the safety and feasibility of the NT strategy.

In this study, we found that the no routine placement of chest tube drainage after thoracoscopic lung resection can significantly shorten the postoperative hospital stay (SMD = -0.91; 95% CI: -1.20 to -0.61; P < 0.001). However, the meta-analysis of postoperative LOS showed a relatively high heterogeneity (I² = 83%; P < 0.001), which might derive from the different surgical approaches (wedge resection, segmentectomy, and lobectomy) and medical insurance of regions and countries. For example, the healthcare system in Japan allows patients to stay in the hospital for a relatively long period of time, even if they have already met discharge criteria (34). It is worth mentioning that the difference of postoperative LOS became statistically insignificant in the lobectomy or segmentectomy subgroup (SMD = -0.30; 95% CI: -0.91 to 0.32; P = 0.34). However, this might be caused by too few (only two) studies in this subgroup, and the effectiveness of NT strategy for lobectomy or segmentectomy warrants further exploration in future studies.

The main concerns caused by omitting routine placement of chest tube drainage after pulmonary resection are the risks of pneumothorax, bleeding, pleural effusion, and subcutaneous emphysema (8, 35). In terms of postoperative complications, we did not perform a pooled analysis of the overall incidence of complications because of the small number of studies reporting it. Instead, we performed a meta-analysis of more detailed complications. The results of the meta-analysis indicated that the incidence of pneumothorax was significantly increased in the NT group (RR = 1.75; 95% CI: 1.14–2.68; P = 0.01). However, there was no significant difference between the two groups in the incidence of pleural effusion (RR = 1.48; 95% CI: 0.62–3.50; P = 0.37) and subcutaneous emphysema (RR = 1.04; 95% CI: 0.65–1.65; P = 0.88). Notably, the reintervention rates of the NT group did not significantly increase (RR = 1.04; 95% CI: 0.48–2.25; P = 0.92), suggesting that the vast majority of pneumothorax could be self-absorbed safely without chest tube reinsertion or thoracocentesis.

The traditional drainage tube is often reported as one of the main reasons of postoperative pain and might interfere with postoperative activity, which could prevent patients from functional rehabilitation and thus prolong the duration of hospitalization (21, 36). In this study, we found that the pain scores on POD 1 (SMD = -0.95; 95% CI: -1.54 to -0.36; P = 0.002), POD 2 (SMD = -0.37; 95% CI: -0.63 to -0.11; P = 0.005), and POD 3 (SMD = -0.39; 95% CI: -0.71 to -0.06; P = 0.02) were significantly decreased without routine chest tube placement. However, the pain scores became comparable between the two groups on POD 7 (SMD = -0.44; 95% CI: -1.06 to 0.17; P = 0.16), indicating that the chest tube is one of the major sources of postoperative pain. Enhanced postoperative pain would prevent patients from effective coughing and thus deteriorate the ventilation capacity. A study performed by Ueda et al. (37) in 2019 showed that the omission of chest tube drainage could reduce the pain and preserve the ventilatory capacity and exercise capacity in the early postoperative period for patients undergoing thoracoscopic pulmonary resection. In addition, there was no significant different in wound healing satisfaction postoperatively between the two groups (RR = 1.04; 95% CI: 0.92–1.17; P = 0.52), which might be attributed to the benefits of minimally invasive technology such as video-assisted thoracoscopic surgery.

To ensure the security of the NT strategy, patients should undergo rigorous air tightness tests before being assigned to the NT group. Water-seal air tightness test and suction-induced air leakage test are relatively common methods to test air leaks during the operation and were applied in majority of the studies. If no air leaks were observed in the air tightness tests, then the patients would be assigned to the NT group. Liu Z et al. (23) have reported a modified air leak test in 2020. The water-seal test was first used at the end of the operation, and then patients were changed to reverse Trendelenburg position with 30° with a chest tube placed at the posterior one-third position of the incision to further test for existence of air leaks. They suggested that complete air drainage is more easily achieved by a chest tube in this position (23). In recent years, a digital drainage system (DDS) has also been used for air tightness tests. A single chest tube was placed through the incision into the pleural cavity before closing the incision and was connected to a DDS. If the DDS indicated 0 ml/min airflow before completion of the wound closure, the chest tube would be removed immediately (22, 38). A study performed by Russo et al. (27) in 1998 used an early removal of chest tube approach. Patients assigned to the NT group had their chest tubes removed within 90 min postoperatively in the recovery room (27). Although this approach was not a strict NT strategy, we still included this study in our analysis because traditional chest tube management tends to keep the chest tube inserted for at least 24 h. Some argued that the operation duration may be extended due to the implementation of the air tightness tests (23, 32). However, our meta-analysis suggested that the operation duration was comparable between the two groups (SMD = -0.10; 95% CI: -0.55 to 0.35; P = 0.66).

At present, the NT strategy mainly includes two methods: prophylactic air-extraction catheter insertion procedure and complete omission of chest tube drainage. Prophylactic air-extraction catheter insertion procedure was first reported by Zhang et al. (32) in 2018. In this procedure, a two-lumen central venous catheter (20 cm, 7 Fr) was inserted into the second intercostal space before directly closing the incision. The air extraction was performed using an injector through the preset catheter if the chest roentgenogram revealed a pneumothorax on POD 1. A recent randomized clinical trial performed by Zhang et al. (31) in 2020 has demonstrated that the prophylactic air-extraction catheter insertion was a safe procedure that could reduce pain and facilitate patients’ recovery after pulmonary wedge resection. However, which of the two methods is better has not been discussed. We originally intended to conduct a subgroup analysis to explore this issue, but due to the insufficient data on prophylactic air-extraction catheter procedure, our idea was not implemented, which could be considered in a future meta-analysis.

It is noteworthy that the selection criteria for patients who do not routinely place chest tubes after video-assisted thoracoscopic pulmonary resection are relatively strict. Important factors that should be considered when selecting patients are the following: 1) absence of air leaks during the intraoperative air tightness tests, 2) absence of dense pleural adhesion, 3) absence of a history of previous ipsilateral thoracic surgery, 4) absence of moderate-to-severe obstructive or restrictive pulmonary diseases.

This study has several limitations that should be considered. First, the majority of the included studies were single-center retrospective cohort studies, and only 2 RCTs were included. Some biases common to cohort studies are unavoidable, such as cohort selection bias, which might have reduced the reliability of the results. Second, different surgical approaches and different pain rating scales were included in this meta-analysis, which inevitably increase the clinical heterogeneity. In addition, prophylactic air-extraction catheter insertion procedure and complete omission of chest tube drainage were both included in the NT group, possibly leading to heterogeneity of the results. Third, although 12 studies were included for analysis, not all studies reported the outcomes we were interested in and we just used the available data to analyze in each comparison. In addition, we did not perform subgroup analyses for outcomes other than postoperative LOS due to the limited data reported. Fourth, all of the studies included had their own criteria to select patients into the NT groups; this might lead to different baseline characteristics of the two groups and a high clinical heterogeneity. Finally, a certain language-based bias might have arisen due to the requirement of full-text English language literature.

This systematic review and meta-analysis is the most up-to-date and comprehensive review of the literature on the NT strategy after video-assisted thoracoscopic pulmonary resection. The NT strategy could not only significantly shorten the postoperative LOS but also reduce short-term postoperative pain for patients without increasing the reintervention rate, suggesting that it is safe and feasible for selected patients scheduled for video-assisted thoracoscopic pulmonary resection.

The original contributions presented in the study are included in the article/Supplementary Material. Further inquiries can be directed to the corresponding author.

Conception and design: RL and HT. Administrative support: HT, WY and ZM. Provision of study materials or patients: RL and JQ. Collection and assembly of data: RL, JQ, KW and YZ. Data analysis and interpretation: RL, JQ and CQ. All authors contributed to the article and approved the submitted version.

This work was funded by National Key Research and Development Program (2021YFC2500904, and 2021YFC2500905), Natural Science Foundation of Shandong Province (ZR2021LSW006) and the Taishan Scholar Program of Shandong Province (no. ts201712087).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.