All patients who underwent fully robot-assisted esophagectomy at the Department for Visceral, Thoracic, and Vascular Surgery at the University Hospital Dresden between 31 August 2018 and 04 August 2022 were included in this retrospective analysis.

Inclusion criteria were biopsy confirmed malignant esophageal or esophagogastric junction tumor [adenocarcinoma (AC), squamous cell carcinoma, and other malignant tumors], elective fully robotic esophagectomy via an abdomino-thoracic approach (Ivor Lewis), reconstruction with gastric conduit pull-up and intrathoracic anastomosis using a circular stapler.

Exclusion criteria were benign histology, emergency operations, open or hybrid esophagectomy, cervical anastomosis, colon conduit, intrathoracic anastomosis using a linear stapler, placement of additional left-sided chest drains, and patients’ death in hospital or within the first 30 postoperative days (PODs).

The study protocol was reviewed by a local ethics committee (EK-84022022) and was performed in accordance with the Declaration of Helsinki and its later amendments. Some of the analyzed patient collectives have already been published regarding other end points (19, 20).

Data were collected retrospectively from the hospitals database and patients’ records by two independent investigators. General complications were graded according to Clavien–Dindo (21) and specific complications after esophagectomy were graded according to the Esophagectomy Complications Consensus Group (ECCG) (22).

The surgical technique of RAMIE has been described elsewhere (23).

In our department, the surgical procedure for esophageal resections was changed to RAMIE in August 2018. Initially, the standard insertion of two intercostal chest drains (24 Ch, recessus and apical via robotic trocars R1 and R3) was performed. From November 2020, we changed the routine placement of the right-sided chest drains to a single-intercostal drain (24 Ch, apical via robotic trocar R3) (Supplementary Figures S1,S2).

According to the standard algorithm, chest x-ray is performed after surgery on admission to the intensive care unit and then every 2 days from the second POD onward to check dilatation of gastric conduit.

Before November 2020, the first peri-anastomotic apical chest drain was removed earliest on POD 2 independent of the daily secretion amount if there is no evidence of air leak (<100 ml/min), pneumothorax > 2.5 cm, chyle leak, purulent secretion, or bleeding. The second recessus chest drain was removed if the daily secretion was below 200 ml per 24 h and if there was still no evidence of air leak (<100 ml/min.), pneumothorax > 2.5 cm, chyle leak, purulent secretion, or bleeding followed by chest x-ray for control.

After change of drain management November 2020, the single drain was removed if the daily secretion was below 200 ml per 24 h and if there was still no evidence of air leak (<100 ml/min), pneumothorax > 2.5 cm, chyle leak, purulent secretion, or bleeding followed by chest x-ray for control.

According to the standard algorithm, thoracic epidural catheter is placed in the absence of contraindications and in case of patient consent in every patient undergoing RAMIE in our institute. It is placed preoperatively (before induction of anesthesia) at the thoracic vertebral level 6–9. Initially, ropivacaine hydrochloride 0.2% plus 0.5 µg/ml sufentanil is administered. In the further postoperative course, only ropivacaine hydrochloride 0.2% is administered. The concomitant pain medication consisting of 1 g of metamizole alternatively 1 g paracetamol four times daily may be extended to 10 mg extended release oxycodone every 12 h and an on-demand medication of 10 mg immediate release oxycodone if the pain score is persistent >4 on the numeric rating scale (NRS). The epidural catheter running rate and dosage is checked daily by the anesthesia pain service and adjusted to the individual needs of the patient (including the increase of the basal rate to max. 8 ml/h, reducing/terminating the basal rate of continuous epidural infusion and removal of the catheter).

Statistical analyses were performed using SPSS (version 28.0, IBM Corp., Armonk, NY, United States). Continuous variables were presented as mean ± SD or median with interquartile range. Continuous data were compared using Student’s t-test if the variables were normally distributed. The Mann–Whitney U test was used to compare continuous non-parametric variables. Categorical variables were compared using chi-square or Fisher’s exact tests. The significance level was set at p = 0.05.

To ensure better comparability between single and double drain cohorts, a 1:1 propensity score matching was performed. The following variables were used to calculate the propensity score using the following regression models: sex, age, body mass index (BMI), American Society of Anesthesiologists Classification (ASA), Charlson comorbidity index (CCI), neoadjuvant treatment, adjuvant treatment, histology, and pathologic Union for International Cancer Control (UICC) stage. Subsequently, the nearest neighbor method with a caliber width of 0.1 was used to find matching pairs.

Between 2018 und 2022, 194 patients underwent Ivor Lewis esophagectomy for malignant disease at our center. Seventy-four patients met inclusion criteria for this study (Supplementary Table S1).

After propensity score matching, 22 patients per group were included into this analysis.

Patients were 61.7 ± 10.6 years old and predominantly male (n = 37, 84.1%).

Most patients had adenocarcinoma (n = 30, 68.1%) and underwent neoadjuvant therapy (n = 39, 88.6%). Neoadjuvant chemotherapy was administered in 24 patients (54.5%) and neoadjuvant chemoradiation in 15 patients (34.1%).

After propensity score matching; patients were comparable regarding baseline characteristics including age, BMI, CCI, ASA classification, comorbidities, histology, neoadjuvant therapy, and UICC clinical stage within the single and double chest drain group (Table 1).

The first chest drain was removed earlier in the double drain group than in the single drain group but without significance (POD 6.68 ± 4.37 vs. POD 5.77 ± 1.8, p = 0.42, Table 2).

In the double drain group, the final chest drain was removed significantly later than in the single drain group (POD 6.68 ± 4.37 vs. POD 9.41 ± 2.72, p = 0.004, Figure 1).

Drain volume from POD 1–5 and total drain volume until removal of last chest drain were comparable between both groups (2,450 ± 1,511 ml vs. 2,809 ± 1,210 ml, p = 0.39; 3,200 ± 2,563 ml vs. 3,243 ± 15,923 ml, p = 0.41, Figure 2).

After removal of the final chest drain, radiological diagnostics (chest x-ray and/or CT scan) showed right-sided pneumothorax in 5 (22.7%) patients in the single drain and 2 (9.1%) patients of the double drain group (p = 0.21, Table 3). In the single drain group, right-sided pneumothorax was clinically relevant Clavien–Dindo Classification (CDC) IIIa and required re-placement of chest drain in only 2 (9.1%) patients 0.43 days (±0.79) after chest drain removal, in the double drain group no patient required re-placement of chest drains (p = 0.30).

Although rate of right-sided pleural effusion after drain removal was high in both groups (n = 12, 54.5%, vs. n = 10, 45.5%, p = 0.38), only one patient in the single drain group had clinically relevant pleural effusion (CDC IIIa) and received interventional pleural catheterization 7 days after chest drain removal. No patient in the double drain group had clinically relevant pleural effusion (p = 1.0).

Double drain patients had a significantly higher overall number of left-sided pleural effusions/pneumothorax (19 (86.4%) vs. 13 (59.1%), p = 0.04) diagnosed by imaging after drain removal on the right side. Of these, no pneumothorax or pleural effusion was deemed to be clinically relevant and required re-chest drain in both groups.

The rate of thoracic CT drainages or re-operations did not differ between both groups (n = 1 (4.5%) vs. n = 0, p = 1.0; n = 3 (13.6%) vs. n = 0, p = 0.12).

No difference in the total number of postoperative chest radiographs (p = 0.93) or computed tomography of chest/abdomen (p = 0.40) could be detected between the single and the double drain group patients.

In both groups, the majority of patients had a perioperative epidural catheter [n = 17 (77.3%) vs. n = 14 (63.6%), p = 0.27, Supplementary Table S2].

Despite epidural catheter, additional pain medication was necessary for 15.4 ± 5.1 days in the single drain and 16.8 ± 7.3 days in the double drain group (p = 0.45).

Neither duration of epidural catheter nor total (6.8 ± 2.1 days vs. 6.6 ± 2.0 days, p = 0.7), oral (7.5 ± 4.9 days vs. 7.9 ± 4.4 days, p = 0.8) or intravenous (9.1 ± 5.3 days vs. 6.9 ± 2.7 days, p = 0.21) pain medication differed significantly between the two groups.

Complications CDC> IIIa occurred in four patients (18.2%) in the single drain and in two patients (9.1%) in the double drain group (p = 0.66, Table 4).

Consequently, frequent perioperative complications such as anastomotic leakage, pneumonia, and Delayed gastric conduit emptying (DGE) were equally distributed between the single drain and double drain group (Table 4).

Intensive care unit (ICU) stay of single drain patients was significantly shorter with 4.2 ± 5.1 days vs. 5.3 ± 3.5 days (p = 0.01), LOS was comparable in both groups (18.3 ± 6.2 vs. 18.0 ± 7.3, p = 0.77). One patient died in the single drain group within 90 days and no death occurred in the double drain group (p = 0.31).