Reducing Thoracic Operative Time to Mitigate Post-Esophagectomy Pneumonia: A Retrospective Cohort Study of an Institutional Transition from RAMIE to C-MIE/VATS

Reducing Thoracic Operative Time to Mitigate Post-Esophagectomy Pneumonia: A Retrospective Cohort Study of an Institutional Transition from RAMIE to C-MIE/VATS | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Reducing Thoracic Operative Time to Mitigate Post-Esophagectomy Pneumonia: A Retrospective Cohort Study of an Institutional Transition from RAMIE to C-MIE/VATS Takeshi Matsubara, Hiroki Okamura, Yohei Sasaki, Shunsuke Kaji, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8656065/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract Background: Postoperative pneumonia after esophagectomy is associated with worse postoperative recovery and long-term survival. At our institution, robot-assisted minimally invasive esophagectomy (RAMIE) was introduced in 2018 but was associated with prolonged thoracic operative time and frequent pneumonia; therefore, we adopted a conventional minimally invasive thoracic approach using video-assisted thoracoscopic esophagectomy (C-MIE/VATS) from 2024. Methods: We retrospectively analyzed 145 consecutive patients who underwent esophagectomy between January 2014 and November 2025. Thoracoscopic cases were stratified by era as pre-2024 (V-1) and from 2024 onward (V-2) and compared with the RAMIE group (R). The primary endpoint was postoperative pneumonia within 30 days after surgery, diagnosed using clinical and radiologic criteria (fever and inflammatory response with new pulmonary infiltrates on chest radiography or computed tomography) and graded using the Clavien–Dindo classification; events of CD grade ≥ II were counted for the primary analysis. Secondary endpoints included operative variables, postoperative complications, sputum culture findings, and overall survival (OS). Factors associated with pneumonia were evaluated using uni- and multivariable analyses, and OS was assessed using the Kaplan–Meier method. Results: Among 145 patients (V-1, n = 62; R, n = 54; V-2, n = 29), thoracic operative time was shorter in V-2 than in R (median 194 vs 322 min; p < 0.001). Postoperative pneumonia within 30 days occurred in 20.7% (6/29) of V-2 and 40.7% (22/54) of R (p = 0.089); pneumonia rates differed across the three groups (V-1 17.7%, R 40.7%, V-2 20.7%; p = 0.014). Patients who developed pneumonia had worse overall survival than those without pneumonia (5-year OS 22.8% vs 54.4%; log-rank p = 0.038), and pneumonia was associated with increased mortality in a Cox model (HR 1.81, 95% CI 1.02–3.20). Conclusions: Transition to C-MIE/VATS was associated with substantially shorter thoracic operative time and a numerically lower incidence of postoperative pneumonia. Given the observed association between postoperative pneumonia and worse overall survival, efforts to optimize operative efficiency and strengthen pneumonia-prevention strategies warrant further evaluation. esophagectomy postoperative pneumonia thoracoscopic esophagectomy robot-assisted surgery operative time Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Postoperative pneumonia after esophagectomy is a clinically important complication associated with adverse short-term outcomes and has been linked to functional decline, readmission, and worse long-term survival. Several studies have reported that postoperative infectious complications—particularly pneumonia—are associated with impaired long-term prognosis after esophagectomy [ 1 , 2 ]. With the widespread adoption of minimally invasive esophagectomy, both conventional minimally invasive esophagectomy with video-assisted thoracoscopic surgery (C-MIE/VATS) and robot-assisted minimally invasive esophagectomy (RAMIE) are commonly performed. However, the learning curve for RAMIE and prolonged thoracic operative time during the implementation phase remain important challenges that may influence perioperative morbidity, including pulmonary complications [ 3 – 5 ]. Although RAMIE has demonstrated favorable outcomes compared with open transthoracic esophagectomy in a randomized controlled trial [ 6 ], we observed prolonged operative time after RAMIE implementation at our institution, raising concern about an increased risk of postoperative pneumonia. Because longer operative/anesthesia time has been reported as a risk factor for postoperative pneumonia [ 2 , 7 – 10 ], we transitioned the thoracic approach from RAMIE to C-MIE/VATS from 2024 to prioritize reduction of thoracic operative time. Therefore, this study aimed to evaluate the clinical impact of this approach modification on postoperative pneumonia and other perioperative outcomes and to examine the association between postoperative pneumonia and overall survival (OS) in our cohort. Patients and Methods Patients We retrospectively analyzed 145 consecutive patients who underwent curative-intent esophagectomy for esophageal cancer at our institution between January 2014 and November 2025. Patients were classified according to thoracic approach and era into three groups: the RAMIE group (R), the VATS group before 2024 (V-1), and the VATS group from 2024 onward (V-2). The prespecified primary comparison was between the R and V-2 groups, with three-group comparisons performed as reference. Endpoints and definitions The primary endpoint was postoperative pneumonia occurring within 30 days after surgery. Postoperative pneumonia was diagnosed using clinical and radiologic criteria (fever and inflammatory response with new pulmonary infiltrates on chest radiography or computed tomography), in accordance with the Esophagectomy Complications Consensus Group (ECCG) framework [ 3 ]. Severity was graded using the Clavien–Dindo (CD) classification [ 11 ], and events of CD grade ≥ II were counted for the primary analysis. Secondary endpoints included total operative time (min), thoracic operative time (min), blood loss (mL), anastomotic leakage (CD grade ≥ II), recurrent laryngeal nerve palsy (CD grade ≥ I), and sputum culture findings (culture positivity and organism distribution). Overall survival (OS) was also evaluated. Statistical analysis Continuous variables are presented as median (interquartile range (IQR)) and compared using the Mann–Whitney U test for two-group comparisons and the Kruskal–Wallis test for three-group comparisons, as appropriate. Categorical variables are presented as number (n) (%) and were compared using Fisher’s exact test. All tests were two-sided, and p < 0.05 was considered statistically significant. To identify factors associated with postoperative pneumonia, multivariable logistic regression was performed with postoperative pneumonia (yes/no) as the dependent variable. The primary model focused on the association between thoracic operative time and pneumonia; therefore, the thoracic approach (RAMIE vs C-MIE/VATS) was not included because it is an upstream determinant of thoracic operative time, and simultaneous adjustment may result in overadjustment and/or multicollinearity. Sensitivity analyses included an additional model incorporating the thoracic approach and stratified analyses to assess robustness. OS was estimated using the Kaplan–Meier method and compared using the log-rank test. The association between postoperative pneumonia and OS was evaluated using a Cox proportional hazards model, reported as hazard ratios (HRs) and 95% confidence intervals (CIs). Median follow-up time was calculated using the reverse Kaplan–Meier method. Statistical analyses were performed with JMP 18 Student Edition (SAS Institute Inc., Cary, NC, USA). To descriptively assess temporal changes in thoracic operative time among thoracoscopic esophagectomy cases, thoracic operative time was also reviewed in chronological case order. Ethics approval and consent procedures are described in the Declarations section. Results Study population A total of 145 patients were included (V-1, n = 62; R, n = 54; V-2, n = 29). The median follow-up for the entire cohort was 1,675 days; by group, it was 2,220 days (V-1), 1,195 days (R), and 286 days (V-2). Patient characteristics (R group vs V-2 group) Baseline characteristics were broadly comparable between the R and V-2 groups (Table 1 ). Median age [IQR] was 71 [65–75] years in the R group and 72 [65–75] years in the V-2 group. All patients in V-2 were male (29/29, 100%) compared with 88.9% (48/54) in R. A history of smoking was similar between groups (R, 83.3% vs V-2, 82.8%) and FEV1.0% (R, 74.1% vs V-2 69.8%) were similar. Neoadjuvant therapy was more frequently in V-2 (R, 64.8% vs V-2 79.3%). Table 1 Patient characteristics (V-1, R, and V-2 groups) Variable V-1 (n = 62) R (n = 54) V-2 (n = 29) p (R vs V-2) Age (years) 67 [62–71.8] 71 [65–74.8] 72 [65–75] 0.48 Male sex 51/62 (82.3%) 48/54 (88.9%) 29/29 (100.0%) 0.08 Smoking history 51/62 (82.3%) 45/54 (83.3%) 24/29 (85.7%) 1.0 FEV1.0 (%) 75.0 [70.8–80.9] 74.1 [67.6–78.3] 69.8 [66.3–75.9] 0.42 Diabetes mellitus 16/62 (25.8%) 10/54 (18.5%) 6/29 (20.7%) 1.0 ASA class ≤ 2 / ≥3 56/6 43/11 21/8 0.75 Neoadjuvant therapy 20/62 (32.3%) 35/54 (64.8%) 23/29 (79.3%) 0.43 Footnote: Continuous variables are presented as median [interquartile range, IQR], and categorical variables as n (%). The primary comparison was R vs V-2. Perioperative outcomes (R group vs V-2 group) Total operative time and thoracic operative time were shorter in V-2 than in R (Table 2 , Fig. 1 ). Median total operative time [IQR] was 744.5 [662.8–791.8] min in R vs 449.0 [242.0–527.0] min in V-2 ( p < 0.001). Median thoracic operative time [IQR] was 322.0 [291.8–361.0] min in R and 194.0 [178.0–219.0] min in V-2 ( p < 0.001). Median estimated blood loss [IQR] was comparable between groups (median [IQR], 150 [90–280] mL vs 190 [70–340] mL; p = 0.77). The rates of anastomotic leakage (CD grade ≥ II) and recurrent laryngeal nerve palsy (CD grade ≥ I) did not differ between groups (Table 2 ): leakage, 35.2% (19/54) vs 24.1% (7/29) ( p = 0.33); palsy, 18.9% (10/54) vs 24.1% (7/29) ( p = 0.58). Table 2 Perioperative outcomes (operative variables and postoperative complications) Variable V-1 (n = 62) R (n = 54) V-2 (n = 29) p (R vs V-2) Total operative time (min) 655 [599.8–762.8] 744.5 [662.8–791.8] 449 [242–527] < 0.01 Thoracic operative time (min) 277.5 [241.2–313.5] 322 [291.8–361] 194 [178–219] < 0.01 Blood loss (mL) 100 [62.5–327.5] 150 [90–280] 190 [70–340] 0.76 Postoperative pneumonia 11/62 (17.7%) 22/54 (40.7%) 6/29 (20.7%) 0.08 Anastomotic leakage 17/62 (27.4%) 19/54 (35.2%) 7/29 (24.1%) 0.33 Recurrent laryngeal nerve palsy 13/62 (21.0%) 10/54 (18.9%) 7/29 (24.1%) 0.58 Footnote: Continuous variables are presented as median [IQR], and categorical variables as n (%). The primary comparison was R vs V-2. Postoperative pneumonia Postoperative pneumonia within 30 days occurred in 40.7% (22/54) of patients in R and 20.7% (6/29) in V-2 (p = 0.089) (Fig. 2 ). In the three-group comparison, pneumonia rates differed among groups (V-1, 17.7% [11/62]; R, 40.7% [22/54]; V-2, 20.7% [6/29]; p = 0.014). In univariable analysis, longer thoracic operative time was associated with postoperative pneumonia, and this association remained significant in the multivariable model that did not include thoracic approach (Table 3 ). Sensitivity analyses that additionally adjusted for thoracic approach and stratified analyses by approach showed results consistent in direction with the primary analysis, although effect estimates were attenuated. Table 3 Risk factors for postoperative pneumonia (univariable and multivariable logistic regression analyses) Variable Univariable OR (95% CI) p Multivariable OR (95% CI) p Age (> 70 years) 0.75 (0.35–1.59) 0.46 1.35 (0.58–3.16) 0.49 Male sex 1.23 (0.41–4.62) 0.99 0.79 (0.18–3.63) 0.74 BMI (≤ 20 kg/m²) 1.65 (0.76–3.55) 0.19 1.44 (0.57–3.59) 0.44 ASA class (≥ 3) 1.07 (0.39–2.71) 0.89 1.13 (0.33–3.92) 0.85 FEV1.0% (≤ 75) 1.32 (0.63–2.84) 0.46 0.94 (0.40–2.17) 0.88 Smoking history 2.99 (0.96–13.3) 0.09 5.78 (1.05–31.8) 0.02 Diabetes mellitus 1.59 (0.67–3.63) 0.28 1.50 (0.56–4.03) 0.43 Neoadjuvant therapy 1.45 (0.69–3.13) 0.33 0.77 (0.31–1.94) 0.58 Thoracic approach (RAMIE) 2.99 (1.42–6.46) < 0.01 — — Thoracic operative time(≥ 290min) 2.92 (1.33–6.71) < 0.01 3.11 (1.28–7.55) 0.01 Recurrent laryngeal nerve palsy 0.97 (0.38–2.35) 0.95 0.85 (0.30–2.42) 0.75 Footnote: ORs are presented with 95% CIs. The multivariable model did not include thoracic approach because it is a strong upstream determinant of operative time; sensitivity analyses including thoracic approach were performed separately. Sputum culture findings Among 39 patients who developed pneumonia (V-1, n = 11; R, n = 22; V-2, n = 6), sputum cultures were positive in all cases (39/39, 100%). Monomicrobial growth occurred in 25 patients (64.1%), and growth of two organisms occurred in 14 (35.9%). Among 53 isolates, gram-negative bacteria predominated (37/53, 69.8%); at least one gram-negative organism was detected in 33/39 patients (84.6%). The most frequently isolated organisms were Enterobacter cloacae (n = 5), Pseudomonas aeruginosa (n = 5), Klebsiella pneumoniae (n = 4), Escherichia coli (n = 4), and Staphylococcus aureus (n = 4). Candida species were detected in five patients (12.8%) (Fig. 3 ). Because sputum cultures may reflect colonization and oropharyngeal flora, these results are presented descriptively as organism distribution at pneumonia onset and were interpreted in conjunction with clinical findings. Overall survival (OS) Patients with postoperative pneumonia (n = 39) had worse OS than those without pneumonia (n = 106) (log-rank p = 0.038) (Fig. 4 ). Estimated OS was 76.7% vs 90.8% at 1 year, 54.7% vs 66.4% at 3 years, and 22.8% vs 54.4% at 5 years. In a univariable Cox proportional hazards model, pneumonia was associated with increased mortality (HR 1.81, 95% CI 1.02–3.20; p = 0.041). Exploratory comparison of OS by surgical approach showed no statistically significant difference (log-rank p = 0.156), which may be influenced by the short follow-up in V-2 (median 286 days). Discussion In this retrospective single-center cohort, we transitioned the thoracic approach from RAMIE to C-MIE/VATS from 2024 onward after observing prolonged thoracic operative time during the RAMIE implementation phase. This modification was accompanied by substantial reductions in total and thoracic operative time and a numerically lower incidence of postoperative pneumonia. In multivariable analysis, longer thoracic operative time remained associated with postoperative pneumonia after adjustment for patient-related factors. Prolonged operative/anesthetic exposure may contribute to atelectasis, impaired secretion clearance, and prolonged ventilatory support, thereby increasing pneumonia risk; therefore, improving operative efficiency may be clinically relevant for reducing perioperative respiratory events [ 2 , 5 , 9 , 10 ]. Prolonged operative and anesthesia time has also been reported as a risk factor for postoperative pneumonia [ 2 ]. The marked reduction in thoracic operative time observed after the transition may reflect procedural standardization and increasing team experience, consistent with the learning-curve literature for minimally invasive and robotic esophagectomy [ 7 , 8 ]. To specifically evaluate the association between thoracic operative time and postoperative pneumonia, we did not include thoracic approach in the primary multivariable model. Because thoracic approach is an upstream determinant of thoracic operative time, simultaneous adjustment for both variables could result in overadjustment and multicollinearity, potentially obscuring the association of interest; sensitivity analyses incorporating thoracic approach showed directionally consistent results with attenuated effect estimates. Postoperative pneumonia was also associated with worse overall survival (OS) in our cohort. Beyond early clinical deterioration and prolonged hospitalization, pneumonia may adversely affect long-term outcomes through delayed rehabilitation, persistent dysphagia and aspiration risk, recurrent infections, sustained systemic inflammation, and delays or discontinuation of adjuvant therapy. Our findings align with prior reports indicating that postoperative infectious complications—particularly pneumonia—are associated with impaired long-term prognosis after esophagectomy [ 1 – 4 , 12 , 13 ]. Perioperative inflammation has been implicated in immunosuppression and tumor progression; for example, elevated postoperative C-reactive protein (CRP) has been associated with worse OS even after minimally invasive esophagectomy [ 13 ]. In addition, serial measurements of CRP and procalcitonin may aid early detection and assessment of infectious complications such as pneumonia and anastomotic leakage [ 14 ]. Postoperative pneumonia likely reflects the combined effects of operative stress and host vulnerability. Sarcopenia and impaired swallowing function have been reported as predictors of postoperative pneumonia, supporting the importance of perioperative nutritional optimization, respiratory rehabilitation, and multidisciplinary aspiration-prevention strategies [ 15 – 18 ]. Consistent with this concept, Kurita et al. reported that preoperative decline in physical and swallowing function was associated with postoperative pneumonia, emphasizing the value of perioperative oral care and swallowing evaluation [ 19 ]. We further described pneumonia cases using sputum culture results as exploratory data. Gram-negative organisms predominated, including Enterobacter , Pseudomonas , Klebsiella , and Escherichia coli , which are commonly implicated in hospital-acquired and aspiration-related pneumonia [ 20 , 21 ]. Together with frequent polymicrobial detection, these findings are compatible with mixed mechanisms, including infectious components and aspiration-related pathophysiology. Prior work has suggested that the detection of target species in early postoperative sputum cultures may predict subsequent pneumonia [ 22 ]. Accordingly, risk-adapted preventive strategies—such as enhanced airway clearance protocols and targeted antimicrobial stewardship—may warrant further investigation [ 23 ]. However, because sputum cultures can reflect colonization as well as infection, these results should be interpreted cautiously. This study has limitations inherent to its retrospective single-center design, and residual confounding (including era effects, team structure, and perioperative management changes) cannot be fully excluded. The primary comparison did not reach statistical significance, likely due to limited sample size in V-2; however, the direction and magnitude were clinically meaningful and consistent with the three-group comparison. In addition, OS comparisons by thoracic approach are constrained by the short follow-up in the V-2 group. Finally, sputum culture results are subject to sampling variability and may not identify causative pathogens. Larger multicenter studies with longer follow-up, standardized pneumonia definitions, and harmonized microbiological sampling are warranted to further clarify pathways linking thoracic operative time, postoperative pneumonia, and long-term outcomes. Conclusion The transition from RAMIE to C-MIE/VATS was associated with shorter thoracic operative time and a numerically lower incidence of postoperative pneumonia in our single-center experience. These findings highlight the potential clinical value of improving operative efficiency and reinforcing pneumonia-prevention strategies after esophagectomy. Multicenter studies with longer follow-up are warranted to confirm generalizability and clarify long-term prognostic implications. Declarations Ethics approval and consent to participate This study was approved by the Institutional Review Board of Shimane University Faculty of Medicine (approval number: 20140331-3). The requirement for informed consent was waived due to the retrospective design, with an opt-out procedure in accordance with institutional policy. Consent for publication Not applicable. Availability of data and materials The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Funding None. Authors’ contributions TM conceived the study. TM collected the data. TM performed the statistical analyses and drafted the manuscript. SK, YS, HO, KI, KI, AK, TT, TT and TY contributed to patient management and data interpretation. MH supervised the study and critically revised the manuscript. All authors read and approved the final manuscript. Acknowledgements Not applicable. Authors’ information (optional) Not applicable. References Tanaka K, Yamasaki M, Kobayashi T, Yamashita K, Makino T, Saito T, et al. Postoperative pneumonia in the acute phase is an important prognostic factor in patients with esophageal cancer. Surgery. 2021;170(2):469–77. Booka E, Kikuchi H, Hiramatsu Y, Takeuchi H. The impact of infectious complications after esophagectomy for esophageal cancer on cancer prognosis and treatment strategy. J Clin Med. 2021;10(19):4614. Low DE, Alderson D, Cecconello I, Chang AC, Darling GE, DʼJourno XB, et al. 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Monitoring sputum culture in resected esophageal cancer patients with preoperative treatment. Dis Esophagus. 2017;30(8):1–9. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 25 Feb, 2026 Reviewers invited by journal 17 Feb, 2026 Editor invited by journal 28 Jan, 2026 Editor assigned by journal 26 Jan, 2026 Submission checks completed at journal 26 Jan, 2026 First submitted to journal 21 Jan, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8656065","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":593948357,"identity":"72c384bb-5795-4d3e-acda-e03380844144","order_by":0,"name":"Takeshi 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University","correspondingAuthor":false,"prefix":"","firstName":"Hiroki","middleName":"","lastName":"Okamura","suffix":""},{"id":593948361,"identity":"521a71f7-e141-4df9-8bd3-3fad3a7783c0","order_by":2,"name":"Yohei Sasaki","email":"","orcid":"","institution":"Shimane University","correspondingAuthor":false,"prefix":"","firstName":"Yohei","middleName":"","lastName":"Sasaki","suffix":""},{"id":593948362,"identity":"bbd4774a-f136-471c-a6d4-91cf87ad90f1","order_by":3,"name":"Shunsuke Kaji","email":"","orcid":"","institution":"Shimane University","correspondingAuthor":false,"prefix":"","firstName":"Shunsuke","middleName":"","lastName":"Kaji","suffix":""},{"id":593948364,"identity":"b857c1c6-a8e9-432b-a113-25f2a9afb73a","order_by":4,"name":"Hikota Hayashi","email":"","orcid":"","institution":"Shimane University","correspondingAuthor":false,"prefix":"","firstName":"Hikota","middleName":"","lastName":"Hayashi","suffix":""},{"id":593948366,"identity":"43d06522-664f-444c-add0-f240d5f4b5a5","order_by":5,"name":"Ryota Masui","email":"","orcid":"","institution":"Shimane University","correspondingAuthor":false,"prefix":"","firstName":"Ryota","middleName":"","lastName":"Masui","suffix":""},{"id":593948367,"identity":"2cda9426-66b9-4daa-b95b-453f259de7a6","order_by":6,"name":"Keisuke Inoue","email":"","orcid":"","institution":"Shimane University","correspondingAuthor":false,"prefix":"","firstName":"Keisuke","middleName":"","lastName":"Inoue","suffix":""},{"id":593948369,"identity":"22bc5867-c23f-4e58-a8e2-7bd5d41789e5","order_by":7,"name":"Ayana Kishimoto","email":"","orcid":"","institution":"Shimane University","correspondingAuthor":false,"prefix":"","firstName":"Ayana","middleName":"","lastName":"Kishimoto","suffix":""},{"id":593948371,"identity":"3d6d7c5b-56ec-4b73-a5cd-b5542ed48aab","order_by":8,"name":"Kazunari Ishitobi","email":"","orcid":"","institution":"Shimane University","correspondingAuthor":false,"prefix":"","firstName":"Kazunari","middleName":"","lastName":"Ishitobi","suffix":""},{"id":593948373,"identity":"f486b6e4-f532-4b09-99f4-79fdfe4ae4da","order_by":9,"name":"Takahito Taniura","email":"","orcid":"","institution":"Shimane University","correspondingAuthor":false,"prefix":"","firstName":"Takahito","middleName":"","lastName":"Taniura","suffix":""},{"id":593948374,"identity":"124a9cc2-6f12-4162-810e-2138093e5672","order_by":10,"name":"Tetsu Yamamoto","email":"","orcid":"","institution":"Shimane University","correspondingAuthor":false,"prefix":"","firstName":"Tetsu","middleName":"","lastName":"Yamamoto","suffix":""},{"id":593948376,"identity":"613afd44-52e3-4e93-8101-ea7e44b8e004","order_by":11,"name":"Masaaki Hidaka","email":"","orcid":"","institution":"Shimane University","correspondingAuthor":false,"prefix":"","firstName":"Masaaki","middleName":"","lastName":"Hidaka","suffix":""}],"badges":[],"createdAt":"2026-01-21 06:42:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8656065/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8656065/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103210432,"identity":"c524e979-0601-4c98-80ff-347772ec6fe8","added_by":"auto","created_at":"2026-02-23 08:26:59","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":87675,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eComparison of total operative time and thoracic operative time (R group vs V-2 group).\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTotal operative time and thoracic operative time were significantly shorter in the V-2 group than in the R group (median 449.0 vs 744.5 min; 194.0 vs 322.0 min; both p\u0026lt;0.001). Boxes indicate the median and interquartile range (IQR); whiskers indicate dispersion and circles indicate outliers. Between-group comparisons were performed using the Mann–Whitney U test.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8656065/v1/696293d16e433c41c13b1080.jpeg"},{"id":103210400,"identity":"fab478be-88ce-44d9-b837-0fca0e21a559","added_by":"auto","created_at":"2026-02-23 08:26:57","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":37411,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eIncidence of postoperative pneumonia (V-1 group, R group, and V-2 group).\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePostoperative pneumonia rates differed significantly among groups (V-1 17.7% [11/62], R 40.7% [22/54], V-2 20.7% [6/29]; p=0.014), with a numerically lower incidence in V-2 than in R (p=0.089). P values were calculated using Fisher’s exact test.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8656065/v1/d8ebda6d959e2536ffd5cd7d.png"},{"id":103210459,"identity":"0a65ba88-7a8e-4a13-bcc6-36a3c05ea440","added_by":"auto","created_at":"2026-02-23 08:27:14","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":76163,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDistribution of organisms detected in sputum cultures among patients with postoperative pneumonia.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAmong 39 pneumonia cases, sputum cultures were positive in all patients (39/39, 100%); gram-negative organisms predominated (37/53 isolates, 69.8%), and 35.9% of cases showed polymicrobial growth. Up to two organisms per patient were recorded (total 53 isolates). Because sputum cultures may reflect colonization and oropharyngeal flora, the figure shows the distribution of detected organisms rather than definitive causative pathogens.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8656065/v1/8c20937c96551cc3f43f7ad7.png"},{"id":103210371,"identity":"f74da4df-c5d9-46a3-8170-c95639d3aade","added_by":"auto","created_at":"2026-02-23 08:26:45","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":21010,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eKaplan–Meier curves for overall survival (OS) according to postoperative pneumonia.\u003cbr\u003e\nOverall survival was significantly worse in patients who developed postoperative pneumonia than in those who did not (log-rank p=0.038), with 5-year OS of 22.8% vs 54.4%, respectively; pneumonia was associated with increased mortality in a univariable Cox model (HR 1.81, 95% CI 1.02–3.20). OS was measured from the date of surgery to death or last follow-up.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8656065/v1/5167fd3dbd7274f246a3151d.png"},{"id":103505227,"identity":"fbc9ea6a-af27-48f6-bc0a-3f2dc1cb6d49","added_by":"auto","created_at":"2026-02-26 13:28:09","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1519201,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8656065/v1/435f42a4-aa83-4273-a4e1-932844d4a6eb.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Reducing Thoracic Operative Time to Mitigate Post-Esophagectomy Pneumonia: A Retrospective Cohort Study of an Institutional Transition from RAMIE to C-MIE/VATS","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePostoperative pneumonia after esophagectomy is a clinically important complication associated with adverse short-term outcomes and has been linked to functional decline, readmission, and worse long-term survival. Several studies have reported that postoperative infectious complications\u0026mdash;particularly pneumonia\u0026mdash;are associated with impaired long-term prognosis after esophagectomy [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWith the widespread adoption of minimally invasive esophagectomy, both conventional minimally invasive esophagectomy with video-assisted thoracoscopic surgery (C-MIE/VATS) and robot-assisted minimally invasive esophagectomy (RAMIE) are commonly performed. However, the learning curve for RAMIE and prolonged thoracic operative time during the implementation phase remain important challenges that may influence perioperative morbidity, including pulmonary complications [\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAlthough RAMIE has demonstrated favorable outcomes compared with open transthoracic esophagectomy in a randomized controlled trial [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], we observed prolonged operative time after RAMIE implementation at our institution, raising concern about an increased risk of postoperative pneumonia. Because longer operative/anesthesia time has been reported as a risk factor for postoperative pneumonia [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan additionalcitationids=\"CR8 CR9\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], we transitioned the thoracic approach from RAMIE to C-MIE/VATS from 2024 to prioritize reduction of thoracic operative time.\u003c/p\u003e \u003cp\u003eTherefore, this study aimed to evaluate the clinical impact of this approach modification on postoperative pneumonia and other perioperative outcomes and to examine the association between postoperative pneumonia and overall survival (OS) in our cohort.\u003c/p\u003e"},{"header":"Patients and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003ePatients\u003c/h2\u003e \u003cp\u003eWe retrospectively analyzed 145 consecutive patients who underwent curative-intent esophagectomy for esophageal cancer at our institution between January 2014 and November 2025. Patients were classified according to thoracic approach and era into three groups: the RAMIE group (R), the VATS group before 2024 (V-1), and the VATS group from 2024 onward (V-2). The prespecified primary comparison was between the R and V-2 groups, with three-group comparisons performed as reference.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eEndpoints and definitions\u003c/h3\u003e\n\u003cp\u003eThe primary endpoint was postoperative pneumonia occurring within 30 days after surgery. Postoperative pneumonia was diagnosed using clinical and radiologic criteria (fever and inflammatory response with new pulmonary infiltrates on chest radiography or computed tomography), in accordance with the Esophagectomy Complications Consensus Group (ECCG) framework [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Severity was graded using the Clavien\u0026ndash;Dindo (CD) classification [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], and events of CD grade\u0026thinsp;\u0026ge;\u0026thinsp;II were counted for the primary analysis.\u003c/p\u003e \u003cp\u003eSecondary endpoints included total operative time (min), thoracic operative time (min), blood loss (mL), anastomotic leakage (CD grade\u0026thinsp;\u0026ge;\u0026thinsp;II), recurrent laryngeal nerve palsy (CD grade\u0026thinsp;\u0026ge;\u0026thinsp;I), and sputum culture findings (culture positivity and organism distribution). Overall survival (OS) was also evaluated.\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eContinuous variables are presented as median (interquartile range (IQR)) and compared using the Mann\u0026ndash;Whitney U test for two-group comparisons and the Kruskal\u0026ndash;Wallis test for three-group comparisons, as appropriate. Categorical variables are presented as number (n) (%) and were compared using Fisher\u0026rsquo;s exact test. All tests were two-sided, and \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003cp\u003eTo identify factors associated with postoperative pneumonia, multivariable logistic regression was performed with postoperative pneumonia (yes/no) as the dependent variable. The primary model focused on the association between thoracic operative time and pneumonia; therefore, the thoracic approach (RAMIE vs C-MIE/VATS) was not included because it is an upstream determinant of thoracic operative time, and simultaneous adjustment may result in overadjustment and/or multicollinearity. Sensitivity analyses included an additional model incorporating the thoracic approach and stratified analyses to assess robustness.\u003c/p\u003e \u003cp\u003eOS was estimated using the Kaplan\u0026ndash;Meier method and compared using the log-rank test. The association between postoperative pneumonia and OS was evaluated using a Cox proportional hazards model, reported as hazard ratios (HRs) and 95% confidence intervals (CIs). Median follow-up time was calculated using the reverse Kaplan\u0026ndash;Meier method. Statistical analyses were performed with JMP 18 Student Edition (SAS Institute Inc., Cary, NC, USA). To descriptively assess temporal changes in thoracic operative time among thoracoscopic esophagectomy cases, thoracic operative time was also reviewed in chronological case order.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eEthics approval\u003c/strong\u003e \u003cp\u003eand consent procedures are described in the Declarations section.\u003c/p\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eStudy population\u003c/p\u003e\n\u003cp\u003eA total of 145 patients were included (V-1, \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;62; R, \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;54; V-2, \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;29). The median follow-up for the entire cohort was 1,675 days; by group, it was 2,220 days (V-1), 1,195 days (R), and 286 days (V-2).\u003c/p\u003e\n\u003cp\u003ePatient characteristics (R group vs V-2 group)\u003c/p\u003e\n\u003cp\u003eBaseline characteristics were broadly comparable between the R and V-2 groups (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). Median age [IQR] was 71 [65\u0026ndash;75] years in the R group and 72 [65\u0026ndash;75] years in the V-2 group. All patients in V-2 were male (29/29, 100%) compared with 88.9% (48/54) in R. A history of smoking was similar between groups (R, 83.3% vs V-2, 82.8%) and FEV1.0% (R, 74.1% vs V-2 69.8%) were similar. Neoadjuvant therapy was more frequently in V-2 (R, 64.8% vs V-2 79.3%).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"char\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\u0026nbsp;\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003ePatient characteristics (V-1, R, and V-2 groups)\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVariable\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eV-1 (n\u0026thinsp;=\u0026thinsp;62)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eR (n\u0026thinsp;=\u0026thinsp;54)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eV-2 (n\u0026thinsp;=\u0026thinsp;29)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e (R vs V-2)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAge (years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e67 [62\u0026ndash;71.8]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e71 [65\u0026ndash;74.8]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e72 [65\u0026ndash;75]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.48\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMale sex\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e51/62 (82.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e48/54 (88.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29/29 (100.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.08\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSmoking history\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e51/62 (82.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e45/54 (83.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24/29 (85.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFEV1.0 (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e75.0 [70.8\u0026ndash;80.9]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e74.1 [67.6\u0026ndash;78.3]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e69.8 [66.3\u0026ndash;75.9]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.42\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDiabetes mellitus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16/62 (25.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10/54 (18.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6/29 (20.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eASA class\u0026thinsp;\u0026le;\u0026thinsp;2 / \u0026ge;3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e56/6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e43/11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21/8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNeoadjuvant therapy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20/62 (32.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35/54 (64.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23/29 (79.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.43\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cstrong\u003eFootnote:\u003c/strong\u003e Continuous variables are presented as median [interquartile range, IQR], and categorical variables as n (%). The primary comparison was R vs V-2.\u003c/p\u003e\n\u003cp\u003ePerioperative outcomes (R group vs V-2 group)\u003c/p\u003e\n\u003cp\u003eTotal operative time and thoracic operative time were shorter in V-2 than in R (Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e, Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). Median total operative time [IQR] was 744.5 [662.8\u0026ndash;791.8] min in R vs 449.0 [242.0\u0026ndash;527.0] min in V-2 (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Median thoracic operative time [IQR] was 322.0 [291.8\u0026ndash;361.0] min in R and 194.0 [178.0\u0026ndash;219.0] min in V-2 (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Median estimated blood loss [IQR] was comparable between groups (median [IQR], 150 [90\u0026ndash;280] mL vs 190 [70\u0026ndash;340] mL; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.77). The rates of anastomotic leakage (CD grade\u0026thinsp;\u0026ge;\u0026thinsp;II) and recurrent laryngeal nerve palsy (CD grade\u0026thinsp;\u0026ge;\u0026thinsp;I) did not differ between groups (Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e): leakage, 35.2% (19/54) vs 24.1% (7/29) (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.33); palsy, 18.9% (10/54) vs 24.1% (7/29) (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.58).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"char\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\u0026nbsp;\u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003ePerioperative outcomes (operative variables and postoperative complications)\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVariable\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eV-1 (n\u0026thinsp;=\u0026thinsp;62)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eR (n\u0026thinsp;=\u0026thinsp;54)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eV-2 (n\u0026thinsp;=\u0026thinsp;29)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e (R vs V-2)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTotal operative time (min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e655 [599.8\u0026ndash;762.8]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e744.5 [662.8\u0026ndash;791.8]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e449 [242\u0026ndash;527]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eThoracic operative time (min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e277.5 [241.2\u0026ndash;313.5]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e322 [291.8\u0026ndash;361]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e194 [178\u0026ndash;219]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBlood loss (mL)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100 [62.5\u0026ndash;327.5]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e150 [90\u0026ndash;280]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e190 [70\u0026ndash;340]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.76\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePostoperative pneumonia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11/62 (17.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22/54 (40.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6/29 (20.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.08\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAnastomotic leakage\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e17/62 (27.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e19/54 (35.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7/29 (24.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRecurrent laryngeal nerve palsy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e13/62 (21.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10/54 (18.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7/29 (24.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cstrong\u003eFootnote:\u003c/strong\u003e Continuous variables are presented as median [IQR], and categorical variables as n (%). The primary comparison was R vs V-2.\u003c/p\u003e\n\u003cp\u003ePostoperative pneumonia\u003c/p\u003e\n\u003cp\u003ePostoperative pneumonia within 30 days occurred in 40.7% (22/54) of patients in R and 20.7% (6/29) in V-2 (p\u0026thinsp;=\u0026thinsp;0.089) (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). In the three-group comparison, pneumonia rates differed among groups (V-1, 17.7% [11/62]; R, 40.7% [22/54]; V-2, 20.7% [6/29]; p\u0026thinsp;=\u0026thinsp;0.014).\u003c/p\u003e\n\u003cp\u003eIn univariable analysis, longer thoracic operative time was associated with postoperative pneumonia, and this association remained significant in the multivariable model that did not include thoracic approach (Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). Sensitivity analyses that additionally adjusted for thoracic approach and stratified analyses by approach showed results consistent in direction with the primary analysis, although effect estimates were attenuated.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eRisk factors for postoperative pneumonia (univariable and multivariable logistic regression analyses)\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVariable\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eUnivariable OR (95% CI)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMultivariable OR (95% CI)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAge (\u0026gt;\u0026thinsp;70 years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.75 (0.35\u0026ndash;1.59)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.35 (0.58\u0026ndash;3.16)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.49\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMale sex\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.23 (0.41\u0026ndash;4.62)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.79 (0.18\u0026ndash;3.63)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.74\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBMI (\u0026le;\u0026thinsp;20 kg/m\u0026sup2;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.65 (0.76\u0026ndash;3.55)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.44 (0.57\u0026ndash;3.59)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eASA class (\u0026ge;\u0026thinsp;3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.07 (0.39\u0026ndash;2.71)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.13 (0.33\u0026ndash;3.92)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.85\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFEV1.0% (\u0026le;\u0026thinsp;75)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.32 (0.63\u0026ndash;2.84)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.94 (0.40\u0026ndash;2.17)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.88\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSmoking history\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.99 (0.96\u0026ndash;13.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.78 (1.05\u0026ndash;31.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.02\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDiabetes mellitus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.59 (0.67\u0026ndash;3.63)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.50 (0.56\u0026ndash;4.03)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.43\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNeoadjuvant therapy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.45 (0.69\u0026ndash;3.13)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.77 (0.31\u0026ndash;1.94)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eThoracic approach (RAMIE)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.99 (1.42\u0026ndash;6.46)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eThoracic operative time(\u0026ge;\u0026thinsp;290min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.92 (1.33\u0026ndash;6.71)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.11 (1.28\u0026ndash;7.55)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRecurrent laryngeal nerve palsy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.97 (0.38\u0026ndash;2.35)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.85 (0.30\u0026ndash;2.42)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cstrong\u003eFootnote:\u003c/strong\u003e ORs are presented with 95% CIs. The multivariable model did not include thoracic approach because it is a strong upstream determinant of operative time; sensitivity analyses including thoracic approach were performed separately.\u003c/p\u003e\n\u003cp\u003eSputum culture findings\u003c/p\u003e\n\u003cp\u003eAmong 39 patients who developed pneumonia (V-1, n\u0026thinsp;=\u0026thinsp;11; R, n\u0026thinsp;=\u0026thinsp;22; V-2, n\u0026thinsp;=\u0026thinsp;6), sputum cultures were positive in all cases (39/39, 100%). Monomicrobial growth occurred in 25 patients (64.1%), and growth of two organisms occurred in 14 (35.9%). Among 53 isolates, gram-negative bacteria predominated (37/53, 69.8%); at least one gram-negative organism was detected in 33/39 patients (84.6%). The most frequently isolated organisms were \u003cem\u003eEnterobacter cloacae\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;5), \u003cem\u003ePseudomonas aeruginosa\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;5), \u003cem\u003eKlebsiella pneumoniae\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;4), \u003cem\u003eEscherichia coli\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;4), and \u003cem\u003eStaphylococcus aureus\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;4). \u003cem\u003eCandida\u003c/em\u003e species were detected in five patients (12.8%) (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). Because sputum cultures may reflect colonization and oropharyngeal flora, these results are presented descriptively as organism distribution at pneumonia onset and were interpreted in conjunction with clinical findings.\u003c/p\u003e\n\u003cp\u003eOverall survival (OS)\u003c/p\u003e\n\u003cp\u003ePatients with postoperative pneumonia (n\u0026thinsp;=\u0026thinsp;39) had worse OS than those without pneumonia (n\u0026thinsp;=\u0026thinsp;106) (log-rank p\u0026thinsp;=\u0026thinsp;0.038) (Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e). Estimated OS was 76.7% vs 90.8% at 1 year, 54.7% vs 66.4% at 3 years, and 22.8% vs 54.4% at 5 years. In a univariable Cox proportional hazards model, pneumonia was associated with increased mortality (HR 1.81, 95% CI 1.02\u0026ndash;3.20; p\u0026thinsp;=\u0026thinsp;0.041).\u003c/p\u003e\n\u003cp\u003eExploratory comparison of OS by surgical approach showed no statistically significant difference (log-rank p\u0026thinsp;=\u0026thinsp;0.156), which may be influenced by the short follow-up in V-2 (median 286 days).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this retrospective single-center cohort, we transitioned the thoracic approach from RAMIE to C-MIE/VATS from 2024 onward after observing prolonged thoracic operative time during the RAMIE implementation phase. This modification was accompanied by substantial reductions in total and thoracic operative time and a numerically lower incidence of postoperative pneumonia. In multivariable analysis, longer thoracic operative time remained associated with postoperative pneumonia after adjustment for patient-related factors. Prolonged operative/anesthetic exposure may contribute to atelectasis, impaired secretion clearance, and prolonged ventilatory support, thereby increasing pneumonia risk; therefore, improving operative efficiency may be clinically relevant for reducing perioperative respiratory events [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Prolonged operative and anesthesia time has also been reported as a risk factor for postoperative pneumonia [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe marked reduction in thoracic operative time observed after the transition may reflect procedural standardization and increasing team experience, consistent with the learning-curve literature for minimally invasive and robotic esophagectomy [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. To specifically evaluate the association between thoracic operative time and postoperative pneumonia, we did not include thoracic approach in the primary multivariable model. Because thoracic approach is an upstream determinant of thoracic operative time, simultaneous adjustment for both variables could result in overadjustment and multicollinearity, potentially obscuring the association of interest; sensitivity analyses incorporating thoracic approach showed directionally consistent results with attenuated effect estimates.\u003c/p\u003e \u003cp\u003ePostoperative pneumonia was also associated with worse overall survival (OS) in our cohort. Beyond early clinical deterioration and prolonged hospitalization, pneumonia may adversely affect long-term outcomes through delayed rehabilitation, persistent dysphagia and aspiration risk, recurrent infections, sustained systemic inflammation, and delays or discontinuation of adjuvant therapy. Our findings align with prior reports indicating that postoperative infectious complications\u0026mdash;particularly pneumonia\u0026mdash;are associated with impaired long-term prognosis after esophagectomy [\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Perioperative inflammation has been implicated in immunosuppression and tumor progression; for example, elevated postoperative C-reactive protein (CRP) has been associated with worse OS even after minimally invasive esophagectomy [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. In addition, serial measurements of CRP and procalcitonin may aid early detection and assessment of infectious complications such as pneumonia and anastomotic leakage [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePostoperative pneumonia likely reflects the combined effects of operative stress and host vulnerability. Sarcopenia and impaired swallowing function have been reported as predictors of postoperative pneumonia, supporting the importance of perioperative nutritional optimization, respiratory rehabilitation, and multidisciplinary aspiration-prevention strategies [\u003cspan additionalcitationids=\"CR16 CR17\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Consistent with this concept, Kurita et al. reported that preoperative decline in physical and swallowing function was associated with postoperative pneumonia, emphasizing the value of perioperative oral care and swallowing evaluation [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWe further described pneumonia cases using sputum culture results as exploratory data. Gram-negative organisms predominated, including \u003cem\u003eEnterobacter\u003c/em\u003e, \u003cem\u003ePseudomonas\u003c/em\u003e, \u003cem\u003eKlebsiella\u003c/em\u003e, and \u003cem\u003eEscherichia coli\u003c/em\u003e, which are commonly implicated in hospital-acquired and aspiration-related pneumonia [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Together with frequent polymicrobial detection, these findings are compatible with mixed mechanisms, including infectious components and aspiration-related pathophysiology. Prior work has suggested that the detection of target species in early postoperative sputum cultures may predict subsequent pneumonia [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Accordingly, risk-adapted preventive strategies\u0026mdash;such as enhanced airway clearance protocols and targeted antimicrobial stewardship\u0026mdash;may warrant further investigation [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. However, because sputum cultures can reflect colonization as well as infection, these results should be interpreted cautiously.\u003c/p\u003e \u003cp\u003eThis study has limitations inherent to its retrospective single-center design, and residual confounding (including era effects, team structure, and perioperative management changes) cannot be fully excluded. The primary comparison did not reach statistical significance, likely due to limited sample size in V-2; however, the direction and magnitude were clinically meaningful and consistent with the three-group comparison. In addition, OS comparisons by thoracic approach are constrained by the short follow-up in the V-2 group. Finally, sputum culture results are subject to sampling variability and may not identify causative pathogens. Larger multicenter studies with longer follow-up, standardized pneumonia definitions, and harmonized microbiological sampling are warranted to further clarify pathways linking thoracic operative time, postoperative pneumonia, and long-term outcomes.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe transition from RAMIE to C-MIE/VATS was associated with shorter thoracic operative time and a numerically lower incidence of postoperative pneumonia in our single-center experience. These findings highlight the potential clinical value of improving operative efficiency and reinforcing pneumonia-prevention strategies after esophagectomy. Multicenter studies with longer follow-up are warranted to confirm generalizability and clarify long-term prognostic implications.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eEthics approval and consent to participate\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Institutional Review Board of Shimane University Faculty of Medicine (approval number: 20140331-3). The requirement for informed consent was waived due to the retrospective design, with an opt-out procedure in accordance with institutional policy.\u003c/p\u003e\n\u003cp\u003eConsent for publication\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003eAvailability of data and materials\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003eCompeting interests\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003eFunding\u003c/p\u003e\n\u003cp\u003eNone.\u003c/p\u003e\n\u003cp\u003eAuthors\u0026rsquo; contributions\u003c/p\u003e\n\u003cp\u003eTM conceived the study. TM collected the data. TM performed the statistical analyses and drafted the manuscript. SK, YS, HO, KI, KI, AK, TT, TT and TY contributed to patient management and data interpretation. MH supervised the study and critically revised the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003eAcknowledgements\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003eAuthors\u0026rsquo; information (optional)\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eTanaka K, Yamasaki M, Kobayashi T, Yamashita K, Makino T, Saito T, et al. Postoperative pneumonia in the acute phase is an important prognostic factor in patients with esophageal cancer. Surgery. 2021;170(2):469\u0026ndash;77.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBooka E, Kikuchi H, Hiramatsu Y, Takeuchi H. The impact of infectious complications after esophagectomy for esophageal cancer on cancer prognosis and treatment strategy. J Clin Med. 2021;10(19):4614.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLow DE, Alderson D, Cecconello I, Chang AC, Darling GE, DʼJourno XB, et al. International consensus on standardization of data collection for complications associated with esophagectomy: Esophagectomy Complications Consensus Group (ECCG). Ann Surg. 2015;262:286\u0026ndash;94.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBooka E, Takeuchi H, Nishi T, Kaburagi T, Motoyama S, Nakamura T. Pneumonia has a negative impact on overall survival after esophagectomy for esophageal cancer. World J Surg. 2015;39:2116\u0026ndash;23.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBiere SSAY, van Berge Henegouwen MI, Maas KW, Bonavina L, Rosman C, Garcia JR, et al. Minimally invasive versus open oesophagectomy for patients with oesophageal cancer: a multicentre, open-label, randomised controlled trial. Lancet. 2012;379:1887\u0026ndash;92.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003evan der Sluis PC, van der Horst S, May AM, Schippers C, Brosens LAA, Joore HCA, et al. Robot-assisted minimally invasive thoraco-laparoscopic esophagectomy versus open transthoracic esophagectomy for resectable esophageal cancer: a randomized controlled trial. Ann Surg. 2019;269(4):621\u0026ndash;30.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMorimoto Y, Kawakubo H, Ishikawa A, Matsuda S, Hijikata N, Ando M, et al. Short-term outcomes of robot-assisted minimally invasive esophagectomy with extended lymphadenectomy for esophageal cancer compared with video-assisted minimally invasive esophagectomy: A single-center retrospective study. Asian J Endosc Surg. 2022;15(2):270\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePickering OJ, van Boxel GI, Carter NC, Mercer SJ, Knight BC, Pucher PH. Learning curve for adoption of robot-assisted minimally invasive esophagectomy: a systematic review of oncological, clinical, and efficiency outcomes. Dis Esophagus. 2023;36(6):doac089.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBooka E, Takeuchi H, Nishi T, Kaburagi T, Motoyama S, Nakamura T. The impact of postoperative complications on survival after esophagectomy for esophageal cancer. Med (Baltim). 2015;94:e1369.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMaruyama S, Shoda K, Kawaguchi Y, Higuchi Y, Ozawa T, Nakayama T, et al. Impact of postoperative infectious complications on long-term prognosis after esophagectomy. World J Surg. 2025;49(1):253\u0026ndash;61.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDindo D, Demartines N, Clavien PA. Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg. 2004;240(2):205\u0026ndash;13.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYoshida N, Watanabe M, Baba Y, Iwagami S, Ishimoto T, Iwatsuki M, et al. Risk factors for pulmonary complications after esophagectomy for esophageal cancer. Surg Today. 2014;44(3):526\u0026ndash;32.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMarkar SR, Karthikesalingam A, Low DE. Enhanced recovery pathways lead to an improvement in postoperative outcomes following esophagectomy: systematic review and pooled analysis. Dis Esophagus. 2015;28(5):468\u0026ndash;75.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNozawa Y, Harada K, Noma K, Katayama Y, Hamada M, Ozaki T. Association Between Early Mobilization and Postoperative Pneumonia Following Robot-assisted Minimally Invasive Esophagectomy in Patients with Thoracic Esophageal Squamous Cell Carcinoma. Phys Ther Res. 2024;27(3):121\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOhi M, Toiyama Y, Omura Y, Ichikawa T, Yasuda H, Okugawa Y, et al. Risk factors and measures of pulmonary complications after thoracoscopic esophagectomy for esophageal cancer. Surg Today. 2019;49(2):176\u0026ndash;86.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKaneta A, Sato T, Nakano H, Matsumoto T, Tada T, Watanabe Y, et al. Preoperative bacterial culture can predict severe pneumonia in patients receiving esophagectomy. Fukushima J Med Sci. 2022;68(2):109\u0026ndash;16.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKurita D, Oguma J, Ishiyama K, Hirano Y, Kanamori J, Daiko H. Handgrip Strength Predicts Postoperative Pneumonia After Thoracoscopic-Laparoscopic Esophagectomy for Patients with Esophageal Cancer. Ann Surg Oncol. 2020;27(9):3173\u0026ndash;81.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMinnella EM, Awasthi R, Loiselle SE, Agnihotram RV, Ferri LE, Carli F. Effect of exercise and nutrition prehabilitation on functional capacity in esophagogastric cancer surgery: a randomized clinical trial. JAMA Surg. 2018;153(12):1081\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSoutome S, Yanamoto S, Funahara M, Hasegawa T, Komori T, Yamada SI, et al. Effect of perioperative oral care on prevention of postoperative pneumonia associated with esophageal cancer surgery: a multicenter case-control study with propensity score matching analysis. Med (Baltim). 2017;96(37):e7436.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTamagawa A, Aoyama T, Tamagawa H, Ju M, Komori K, Maezawa Y, et al. Influence of postoperative pneumonia on esophageal cancer survival and recurrence. Anticancer Res. 2019;39(5):2671\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWeijs TJ, Ruurda JP, Nieuwenhuijzen GAP, van Hillegersberg R, Luyer MDP. Strategies to reduce pulmonary complications after esophagectomy. World J Gastroenterol. 2013;19(39):6509\u0026ndash;14.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMatsui K, Kawakubo H, Matsuda S, Mayanagi S, Irino T, Fukuda K, et al. Clinical usefulness of sputum culture on the first postoperative day to predict early postoperative pneumonia after esophagectomy for esophageal cancer. Esophagus. 2021;18(4):773\u0026ndash;82.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKosumi K, Baba Y, Yamashita K, Ishimoto T, Nakamura K, Ohuchi M. Monitoring sputum culture in resected esophageal cancer patients with preoperative treatment. Dis Esophagus. 2017;30(8):1\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bsur","sideBox":"Learn more about [BMC Surgery](http://bmcsurg.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bsur/default.aspx","title":"BMC Surgery","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"esophagectomy, postoperative pneumonia, thoracoscopic esophagectomy, robot-assisted surgery, operative time","lastPublishedDoi":"10.21203/rs.3.rs-8656065/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8656065/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground:\u003c/h2\u003e \u003cp\u003ePostoperative pneumonia after esophagectomy is associated with worse postoperative recovery and long-term survival. At our institution, robot-assisted minimally invasive esophagectomy (RAMIE) was introduced in 2018 but was associated with prolonged thoracic operative time and frequent pneumonia; therefore, we adopted a conventional minimally invasive thoracic approach using video-assisted thoracoscopic esophagectomy (C-MIE/VATS) from 2024.\u003c/p\u003e\u003ch2\u003eMethods:\u003c/h2\u003e \u003cp\u003eWe retrospectively analyzed 145 consecutive patients who underwent esophagectomy between January 2014 and November 2025. Thoracoscopic cases were stratified by era as pre-2024 (V-1) and from 2024 onward (V-2) and compared with the RAMIE group (R). The primary endpoint was postoperative pneumonia within 30 days after surgery, diagnosed using clinical and radiologic criteria (fever and inflammatory response with new pulmonary infiltrates on chest radiography or computed tomography) and graded using the Clavien\u0026ndash;Dindo classification; events of CD grade\u0026thinsp;\u0026ge;\u0026thinsp;II were counted for the primary analysis. Secondary endpoints included operative variables, postoperative complications, sputum culture findings, and overall survival (OS). Factors associated with pneumonia were evaluated using uni- and multivariable analyses, and OS was assessed using the Kaplan\u0026ndash;Meier method.\u003c/p\u003e\u003ch2\u003eResults:\u003c/h2\u003e \u003cp\u003eAmong 145 patients (V-1, n\u0026thinsp;=\u0026thinsp;62; R, n\u0026thinsp;=\u0026thinsp;54; V-2, n\u0026thinsp;=\u0026thinsp;29), thoracic operative time was shorter in V-2 than in R (median 194 vs 322 min; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Postoperative pneumonia within 30 days occurred in 20.7% (6/29) of V-2 and 40.7% (22/54) of R (p\u0026thinsp;=\u0026thinsp;0.089); pneumonia rates differed across the three groups (V-1 17.7%, R 40.7%, V-2 20.7%; p\u0026thinsp;=\u0026thinsp;0.014). Patients who developed pneumonia had worse overall survival than those without pneumonia (5-year OS 22.8% vs 54.4%; log-rank p\u0026thinsp;=\u0026thinsp;0.038), and pneumonia was associated with increased mortality in a Cox model (HR 1.81, 95% CI 1.02\u0026ndash;3.20).\u003c/p\u003e\u003ch2\u003eConclusions:\u003c/h2\u003e \u003cp\u003eTransition to C-MIE/VATS was associated with substantially shorter thoracic operative time and a numerically lower incidence of postoperative pneumonia. Given the observed association between postoperative pneumonia and worse overall survival, efforts to optimize operative efficiency and strengthen pneumonia-prevention strategies warrant further evaluation.\u003c/p\u003e","manuscriptTitle":"Reducing Thoracic Operative Time to Mitigate Post-Esophagectomy Pneumonia: A Retrospective Cohort Study of an Institutional Transition from RAMIE to C-MIE/VATS","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-23 08:24:57","doi":"10.21203/rs.3.rs-8656065/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"136820043877045136466408508077512409965","date":"2026-02-25T13:26:43+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-17T12:44:36+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-01-28T10:32:25+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-27T03:16:11+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-27T03:15:14+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Surgery","date":"2026-01-21T06:19:34+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bsur","sideBox":"Learn more about [BMC Surgery](http://bmcsurg.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bsur/default.aspx","title":"BMC Surgery","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"af031e05-2119-4e43-a127-46da03724c82","owner":[],"postedDate":"February 23rd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-02-23T08:25:04+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-23 08:24:57","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8656065","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8656065","identity":"rs-8656065","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}