Wedge extended bronchoplasty with caliber adjustment by membranous suture.

Extended bronchoplasty for the left lower lobe lung tumors with interlobar lymph node involvement is a useful surgical technique for avoiding pneumonectomy. Typically, sleeve bronchoplasty, in which the superior division bronchus and the left main bronchus are separated and anastomosed, is chosen due to the difference in caliber of the anastomosis; herein, we report a wedge extended bronchoplasty in which the superior division bronchus and the left main bronchus were not completely separated. The main point of this technique is to adjust the difference in caliber by suturing the main bronchial membranes.

Practical methods to differentiate thymic malignancies by positron-emission tomography and tumor markers.

PURPOSE: An accurate diagnosis of thymic malignancies is important, but challenging due to the broad range of differential diagnoses. This study aims to evaluate the efficacy of PET/CT and tumor markers for diagnosing thymic malignancies. METHODS: Patients admitted to our department between January 2012 and December 2021 with primary anterior mediastinal tumors were retrospectively evaluated. We evaluated the relationship between the maximum standardized uptake value (SUVmax), tumor markers, and pathological diagnosis in four groups: thymic carcinoma, thymoma, lymphoma, and others. RESULTS: In total, 139 patients were included in this study. The SUVmax was significantly higher in lymphoma, thymic carcinoma, and thymoma, in that order. The cytokeratin 19 fragment (CYFRA 21-1) was significantly higher in thymic carcinoma than in the other groups. An ROC curve analysis indicated that the optimal cut-off values of SUVmax for thymic carcinoma plus lymphoma and CYFRA 21-1 for thymic carcinoma were 7.97 (AUC = 0.934) and 2.95 (AUC = 0.768), respectively. Using a combination of cut-off values (SUVmax = 8, CYFRA 21-1 = 3), the accuracy rate for diagnosing thymic carcinoma was 91.4%. CONCLUSIONS: The SUVmax and CYFRA 21-1 levels are significant indicators for the diagnosis of thymic carcinoma. Combining these indicators resulted in a more accurate diagnosis of thymic malignancies, which could facilitate the decision-making process for determining the optimal treatment strategies.

Relationship between changes in pulmonary function and patient-reported outcomes of lung cancer surgery.

PURPOSE: To investigate the relationship between changes in pulmonary function (PF) and patient-reported outcomes (PROs) of lung cancer surgery. METHODS: We recruited 262 patients who underwent lung resection for lung cancer, to evaluate the PROs, using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ)-C30 and the Lung Cancer 13-question supplement (LC13). The patients underwent PF tests and PRO assessments preoperatively (Pre) and 1 year after surgery (Y1). Changes were calculated by subtracting the value at Pre from the value at Y1. We set two cohorts: patients under the ongoing protocol (Cohort 1) and patients who were eligible for lobectomy with clinical stage I lung cancer (Cohort 2). RESULTS: Cohorts 1 and 2 comprised 206 and 149 patients, respectively. In addition to dyspnea, changes in PF were also correlated with scores for global health status, physical and role function scores, fatigue, nausea and vomiting, pain, and financial difficulties. Absolute correlation coefficient values ranged from 0.149 to 0.311. Improvement of emotional and social function scores was independent of PF. Sublobar resection preserved PF more than lobectomy did. Wedge resection mitigated dyspnea in both cohorts. CONCLUSION: The correlation between PF and PROs was found to be weak; therefore, further studies are needed to improve the patient's postoperative experience.

Sex-specific emphysematous changes evaluated by a three-dimensional computed tomography volumetric analysis among patients with smoking histories who underwent resection for lung cancer.

PURPOSE: The present study evaluated the sex-specific susceptibility to the development of emphysema in patients with smoking histories who underwent lung cancer surgeries. METHODS: Lung cancer patients with smoking histories who underwent lung resection at the University of Tsukuba Hospital, Japan, were enrolled. Radiologic emphysematous changes were analyzed using three-dimensional computed tomography (3D-CT). The volume proportion of emphysematous lung per unit of smoking and the relationship between emphysematous change and clinicopathologic factors were evaluated. RESULTS: Radiologic emphysematous changes analyzed using 3D-CT per pack-year smoked, defined as the Smoking-Emphysema Index (SEI), were greater in females than males. The difference was more profound in adenocarcinoma patients than in non-adenocarcinoma patients (0.70 ± 2.30 vs. 0.21 ± 0.28, P = 0.037). CONCLUSION: Female lung cancer patients are more susceptible to smoking-induced emphysema than males. The SEI may be an effective indicator for evaluating smoking-induced emphysema.

Three-dimensional analysis reveals a high incidence of lung adenocarcinoma in the upper region.

PURPOSE: The lung is a unique organ with a ventilation-perfusion mismatch, which can cause inhomogeneous incidence rates of lung cancer depending on the location in the lung. We aimed to evaluate the incidence of lung adenocarcinoma in each lobe by analyzing the incidence per unit volume, to evaluate the incidence without being affected by differences in the size of each lobe or in the size of the lungs between individuals. METHODS: The number of adenocarcinomas in each lobe was counted. Lung volumes were measured using a three-dimensional computer workstation. The tumor incidence per unit volume was analyzed based on the number of tumors in each lobe. RESULTS: The number of tumors per unit volume was 0.467 in the right upper lobe (RUL), 0.182 in the right middle lobe, 0.209 in the right lower lobe, 0.306 in the left upper segment (LUS), 0.083 in the left lingular segment, and 0.169 in the left lower lobe. The tumor incidence rate of RUL + LUS was 2.269 times that of the other lobes, a value that was significantly higher when using the bootstrap method (p < 0.001). CONCLUSIONS: The incidence of adenocarcinoma per unit volume in both upper lobes was higher than that in other lobes.

Sphericity of lymph nodes using 3D-CT predicts metastasis in lung cancer patients.

BACKGROUND: The presence of mediastinal lymph node metastasis is important because it is related to the treatment and prognosis of lung cancer. Although prevalently used, evaluation of lymph nodes is not always reliable. We introduced sphericity as a criterion for evaluating morphologic differences between metastatic and nonmetastatic nodes. METHODS: We reviewed the cases of 66 patients with N2 disease and of 68 patients with N0-1 disease who underwent lobectomy with mediastinal dissection between January 2012 and December 2021. The sphericity of the dissected station lymph nodes, which represents how close the node is to being a true sphere, was evaluated along with the diameter and volume. Each parameter was obtained and evaluated for ability to predict metastasis. RESULTS: Metastatic lymph nodes had a larger short-axis diameter (average: 8.2 mm vs. 5.4 mm, p < 0.001) and sphericity (average: 0.72 vs. 0.60, p < 0.001) than those of nonmetastatic lymph nodes. Short-axis diameter ≥ 6 mm and sphericity ≥ 0.60 identified metastasis with 76.2% sensitivity and 70.2% specificity (AUC = 0.78, p < 0.001) and 92.1% sensitivity and 53.9% specificity (AUC = 0.78, p < 0.001), respectively. For lymph nodes with a short-axis diameter ≥ 5 mm, sphericity ≥ 0.60 identified metastasis with 84.1% sensitivity and 89.3% specificity. CONCLUSION: By using 3D-CT analysis to examine sphericity, we showed that metastatic lymph nodes became spherical. Our method for predicting lymph node metastasis based on sphericity of lymph nodes with a short-axis diameter ≥ 5 mm could do so with higher sensitivity than the conventional method, and with acceptable specificity.

Effect of cardiopulmonary bypass on coagulation factors II, VII and X in a primate model: an exploratory pilot study.

OBJECTIVES: The use of cardiopulmonary bypass (CPB) in cardiac surgery is a major risk factor for postoperative bleeding. We hypothesized that consumptive coagulopathy and haemodilution influence the coagulation factors; therefore, we aimed to estimate the activity profiles of coagulation factors II, VII and X during CPB circulation. METHODS: A 120-min bypass was surgically established in cynomolgus monkeys (n = 7). Activities of coagulation factors II, VII and X were measured at 6 time points during the experiment (baseline, 0, 30, 60, 120 min of bypass and 60 min after bypass). To assess the influence of consumptive coagulopathy, the values were adjusted for haemodilution using the haematocrit values. Data were expressed as mean (standard deviation). RESULTS: Activities of coagulation factors decreased during the experiment. In particular, the activities for II, VII and X were decreased the most by 44.2% (5.0), 61.4% (4.3) and 49.0% (3.7) at 30 min following CPB initiation (P < 0.001, P < 0.001 and P < 0.001, respectively). Following adjustments for haemodilution, change magnitudes lessened but remained significant for factor VII. The adjusted concentration of factor VII was observed to decrease from the baseline to the initiation of bypass circulation. CONCLUSIONS: In conclusion, coagulation factor II, VII and X concentrations decreased during CPB. Following adjustment for haemodilution, a decrease in concentration was observed with factor VII.

Comparison of patient-reported outcomes and clinical outcomes between pleurectomy and pleural covering added to thoracoscopic bullectomy for primary spontaneous pneumothorax.

Background: An optimal surgical procedure for primary spontaneous pneumothorax (PSP) has not yet been established. The study aimed to compare patient-reported outcomes (PROs) and clinical outcomes between parietal pleurectomy (pleurectomy) and visceral pleural covering with absorbable prosthesis (covering) added to thoracoscopic bullectomy in patients with PSP. Methods: From January 2015 to April 2018, PROs were prospectively evaluated using EuroQOL-5 dimensions-5 levels (EQ5D). Questionnaires were administered preoperatively and at 1, 3, and 5 days and 1 month postoperatively. The perioperative outcomes were compared retrospectively. Recurrences and postoperative symptoms in the distant period were investigated cross-sectionally by telephone and mail surveys in February 2020. Results: In total, 26 and 29 patients underwent covering and pleurectomy, respectively. The visual analog scale score of the EQ5D on postoperative day 1 was significantly better in the pleurectomy group than in the covering group. There was no significant difference in the frequency of PROs in the EQ5D including pain. Perioperative outcomes, such as postoperative chest tube placement, and hospital stay, were comparable between the groups, except for the operative time. There was no significant difference in the recurrence rate and frequency of residual symptoms, e.g., chest discomfort in the long-term outcomes. Conclusions: PROs and clinical outcomes were comparable between the two procedures. Further studies are required to determine the optimal treatment procedure.

A novel approach to the lung apex avoiding dissection of severe pleural adhesions.

A 70-year-old man was incidentally diagnosed with left pneumothorax. Primary surgery via the caudal thoracic cavity found severe pleural adhesions causing narrowing of the tunnel leading to the lung apex. The point of air leakage was located at the lung apex beyond the tunnel. To stop the air leakage, fibrin glue was injected to the apex via the tunnel; however, leakage reoccurred postoperatively. Considering the lung injury, a novel approach for lung apex without adhesion dissection was chosen for secondary surgery. An axillary skin incision was made at the 2nd intercostal space, and extrapleural dissection proceeded toward the apex. After the pleural space was confirmed by the movement of pleural effusion, the parietal pleura was incised, and a bulla was exposed and resected. The presented procedure to reach the apex of the lung without adhesion dissection could be an option in cases with dense and extensive pleural adhesions.

Myeloid Progenitor Inhibitory Factor-1 (CCL23) Inhibits Lung Leukocyte Recruitment in a Primate Cardiopulmonary Bypass-Induced Pulmonary Ischaemia Model.

BACKGROUND: Bone marrow (BM)-derived polymorphonuclear leukocytes (PMNs) and monocytes (MO) induced by cardiopulmonary bypass (CPB) are highly proteolytic and cause postoperative lung injury. Although CCL23/Myeloid progenitor inhibitory factor-1 is a human CC chemokine with potent suppressor effects on myeloid progenitor cells, in vivo inhibitory effects on BM-derived leukocyte kinetics associated with CPB are unknown. METHODS: Two-hour CPB was surgically performed in cynomolgus monkeys and BM-derived leukocytes kinetics were monitored postoperatively by flow cytometry with 5'-bromo-2'-deoxyuridine (BrdU) and cytokine ELISA. Monkeys were given CCL23 (n=5) or saline (control, n=5) intravenously daily for 3 days before BrdU labelling and peripheral blood/bronchoalveolar lavage fluid (BALF) timepoint sampling to reveal BrdU-labelled cells. Levels of cytokines, CD11b, and L-selectin were considered leukocytic activation markers. RESULTS: The CCL23 treatment significantly prolonged BM transit of leukocytes (PMNs, 118.4±11.7-95.5±4.1 hours [control]; MO, 91.6±5.0-62.0±3.0 hours [control]) and reduced their alveolar appearance. The BM pool size of MO was decreased by CCL23 but PMNs were unaffected. CD11b, L-selectin expression of PMNs and MO during CPB, and post-surgical increases of interleukin (IL)-6, IL-8, TNF-α, MCP-1, and PMN elastase in the BALF were not suppressed. CONCLUSIONS: CCL23 treatment slows turnover of PMN and MO progenitors in BM and suppresses their circulatory release and lung recruitment. CCL23 has inhibitory effects specifically on the CPB-induced BM response and could hold value for preventing CPB-induced lung injury.

Alaska pollock gelatin sealant shows long-term efficacy and safety in a pulmonary air leakage rat model.

OBJECTIVES: Postoperative prolonged air leakage is a frequent complication following lung resection. We have shown the high adhesive quality of a newly developed sealant based on a hydrophobically modified Alaska pollock-derived gelatin (ApGltn) sealant in acute in vivo settings. The purpose of this study was to investigate the long-term efficacy and safety of ApGltn sealant using rats as a preclinical model. METHODS: An air leakage rat model with a 5-mm pleural defect was created, to which ApGltn sealant or fibrin sealant was applied. In both groups, the rats were evaluated on days 1, 7, 14 and 28. In the ApGltn sealant group, days 56 and 84 were added to evaluate absorption as sealant was still present on day 28. The number of rats in each subgroup was 4 (for a total of 40). Lung specimens and blood samples were obtained for histological and haematological assessment. RESULTS: No findings suggesting infection or air leakage were observed. ApGltn sealant was absorbed from day 56 to day 84. Histologically, although neutrophil and lymphocyte infiltrations on the lung side did not differ between groups, those on the sealant side were significantly less in the ApGltn sealant group. Blood sample tests revealed no significant findings suggesting inflammation or organ damage in either group. CONCLUSIONS: ApGltn sealant showed long-term sealing efficacy and safety with mild inflammation in a pulmonary air leakage rat model. ApGltn sealant is expected to be a safe and effective sealant for clinical applications.

Left thoracoscopic sympathectomy for refractory ventricular arrhythmias.

Left cardiac sympathetic denervation is a procedure used to prevent ventricular arrhythmias that remain refractory despite medical treatments. This procedure usually involves the resection of the lower side of the stellate ganglion, which is an uncommon surgical technique due to the limited situations in which it can be applied. Here, we report a case of refractory ventricular arrhythmias and a description of its successful treatment with the method of left cardiac sympathetic denervation using video-assisted thoracotomy.

Impacts of pleural adhesions on lobectomies for malignant lung tumors.

OBJECTIVES: Pleural adhesions are sometimes troublesome in lung lobectomies, and how they affect such surgeries depends on the degree of the adhesion. Herein, pleural adhesions were categorized according to density, tenacity, and coverage, and the impact of each category on lung lobectomy was investigated. METHODS: The cases of 510 patients who consecutively underwent lobectomies were retrospectively reviewed. Pleural adhesions were classified into two classes (non-dense and dense) in the category of "Density," 3 classes (loose, firm, and very-strong) in that of "Tenacity," and 3 classes (1-10%, 10-50%, 50-100%) in that of "Coverage." The perioperative findings for each class were compared with those of patients without pleural adhesions. RESULTS: The 50-100% group in the Coverage category was the most affected by pleural adhesions, and the very-strong group in the Tenacity category was the next. In these 2 groups, when compared with the no-adhesion group, significant differences were found in operative time (336, 326 vs 231 min), amount of bleeding (187.5, 80 vs 20 g), and frequency of prolonged air leakage (20%, 22% vs 3%), respectively. The dense group, firm group, and 10-50% group also significantly affected the perioperative course. As for postoperative complications, prolonged air leakage was the most problematic. CONCLUSIONS: The impact of pleural adhesions on lobectomy would be greater if the pleural adhesion is dense, firm, or very-strong and has a coverage of 10% or more. Careful and patient pleural dissection is required, even if this entails a longer operative time, to minimize postoperative complications.

Increase of Micro-vessels Beneath the Pleural Surface on CT Predicts Pleural Adhesions.

BACKGROUND: Pleural adhesions are often troublesome in lung surgeries. In some dense pleural adhesions, blood vessels between lung and chest wall (BVLC) are found during surgery. Theoretically, BVLC would increase the amount of blood flow just below the visceral pleura and could allow blood vessels beneath the pleural surface to be clearly visualized on CT. In this study, we investigated whether it was possible to identify the typical CT findings of cases with BVLC. METHODS: Medical records and imaging findings of 186 patients who underwent surgery for lung tumors in our institution were retrospectively reviewed. RESULTS: BVLC was found in 56 patients, of whom 44 (79%) had findings on preoperative CT that indicated increase of micro-vessels just below pleura. In the 21 patients with BVLC of ≥1 mm vessel diameter, the same CT findings were recognized in 19 cases (90%). CONCLUSION: Our results indicate that the CT finding of increased micro-vessels just below pleura has the potential to be used as a novel predictor of pleural adhesion.

Rapid enlargement of pulmonary benign metastasizing leiomyoma with fluid-containing cystic change: a case report.

BACKGROUND: Pulmonary benign metastasizing leiomyoma (PBML) is a rare disease that can occur in women with a history of uterine leiomyoma. Despite its benign histological features, like a malignancy, leiomyomas can on rare occasion spread to the lung. Typically, PBML presents with asymptomatic multiple solid lung nodules with slow tumor progression, following hysterectomy. Here, we present an atypical case with rapid enlargement of PBML with fluid-containing cystic change. CASE PRESENTATION: We experienced a case of a 49-year-old woman with bilateral lung nodules following hysterectomy. Two nodules in the right lung had cystic change with fluid in the tumors. Hormone therapy was initiated after surgical biopsy of the left lung confirmed a diagnosis of PBML. However, the cystic component of right upper lobe lesion enlarged rapidly over the following 7 months, and, considering the risk of malignant transformation or tumor rupture, right upper lobectomy was performed. Pathologically, the fluid-containing tumor was diagnosed as PBML. CONCLUSION: Given the risk of rapid progression, we should carefully consider the surgical indications of fluid-containing PBML.

Effect of pulmonary training for community-dwelling frail older adults with chronic stroke: A randomized controlled pilot trial.

Background: Decreased pulmonary function and poor deglutition are a major risk factor for poststroke aspiration pneumonia. We analyzed the benefits of pulmonary training on pulmonary function, deglutition, and quality of life (QOL) in community-dwelling, frail elderly people with chronic stroke. Method: This study was designed as an open, randomized, controlled pilot trial. The participants, who were frail older adults with a history of stroke, were randomized to 2 rehabilitation groups: intervention group (n = 15) and control (n = 15). All participants (65-94 years) attended twelve 20-min sessions twice a week for 6 weeks of either standard rehabilitation (control group) or standard rehabilitation with pulmonary training including home pulmonary exercise (intervention group). The main outcome measures were pulmonary function (%MIP), deglutition (DRACE), and QOL (SF8ï½¥PCS), while secondary outcomes were muscle strength (grip and abdominal), thorax flexibility, 6-min walk distance, and activities in daily living. All outcomes were measured both prior to training and after the 12 sessions. Results: The intervention group showed significant improvement in %MIP (95% CI, 2.9-31.6; p < 0.01), DRACE (95% CI, -4.1-0.1; p < 0.01), and SF8ï½¥PCS (95% CI, 2.5-7.2; p < 0.01) compared with controls. There were no cognitive function decline and higher brain dysfunction. Conclusions: These results suggest that the addition of pulmonary training including home pulmonary exercise to a standard rehabilitation program could improve pulmonary function, deglutition, and QOL in frail elderly people with chronic stroke.

Efficacy of Alaska Pollock Gelatin Sealant for Pulmonary Air Leakage in Porcine Models.

BACKGROUND: Postoperative prolonged air leakage is a frequent complication after lung resection. We have developed a new sealant based on a hydrophobically modified Alaska pollock-derived gelatin (ApGltn) sealant. The purpose of this study was to evaluate the adhesive strength of the ApGltn sealant in comparison with a fibrin sealant using a new spray system in ex vivo and in vivo models. METHODS: Pleural defects in ex vivo and in vivo porcine models were created, to which the ApGltn sealant or the fibrin sealant was applied. The pressure resistance was assessed with a stepwise increase in airway pressure to confirm air leakage from the sealing site. Tissue samples covered with each sealant were obtained for histologic assessment. RESULTS: In the ex vivo experiment, the leak pressures of the ApGltn sealant were significantly greater than those of the fibrin sealant (102.94 ± 15.6 cm H2O and 28.37 ± 5.1 cm H2O, respectively) (P < .01). In the in vivo experiment, the leak pressures of the ApGltn sealant were also significantly greater than those of the fibrin sealant (68.82 ± 18.04 cm H2O and 43.33 ± 7.13 cm H2O, respectively) (P = .043). The histologic examination confirmed that the ApGltn sealant adhered tightly to both the pleura and the surface of the pleural defect. CONCLUSIONS: The ApGltn sealant has sufficiently high adhesive quality in ex vivo and in vivo porcine lungs, which could be considered suitable and effective for use in the prevention of air leakage from the lungs.

Predicting Respiratory Complications Following Lobectomy Using Quantitative CT Measures of Emphysema.

PURPOSE: In performing surgery for lung cancer, emphysema is a risk factor related to postoperative respiratory complications (PRC). However, few studies have addressed the risk of radiological emphysematous volume affecting PRC. The aim of this study was to investigate the relationship between emphysematous volume as measured on 3-dimensional computed tomography and PRC. PATIENTS AND METHODS: We reviewed 342 lung cancer patients undergoing lobectomy between 2013 and 2018. The percentage of low attenuation area (LAA%) was defined as the percentage of the lung area showing attenuation of -950 Hounsfield units or lower. Preoperative factors including age, sex, body mass index, smoking index, respiratory function, tumour histology, and LAA% were evaluated. PRC included pneumonia, atelectasis, prolonged air leakage, empyema, hypoxia, ischemic bronchitis, bronchopleural fistula, and exacerbation of interstitial pneumonia. Uni- and multivariable analyses were performed to investigate the relationship between independent clinical variables and postoperative adverse events. RESULTS: Median LAA% was 5.0% (range, 0-40%) and PRC was observed in 50 patients (14.6%). Patients who presented with PRC showed significantly high LAA% compared to those without complications (median: 8.1% vs 3.8%; p < 0.001). Based on univariable analysis, age, sex, smoking index, percentage of forced expiratory volume in 1 s (FEV1.0%), histology, and LAA% were significant predictors for PRC. Multivariable analysis revealed higher LAA% as a significant risk factor for PRC (odds ratio = 1.040; 95% confidence interval, 1.001-1.080; p = 0.046). CONCLUSION: In addition to respiratory function with spirometry, LAA% can be used as a predictor of PRC.

[Influence of Pleural Adhesions on Thoracoscopic Surgeries for Malignant Lung Tumors].

In the present study, influences of pleural adhesions on thoracoscopic lung surgeries were investigated. A total of 666 consecutive patients who had undergone thoracoscopic surgeries for lung malignant tumors were retrospectively analyzed. Pleural adhesions were present intraoperatively in 289 cases, of which 6 required conversion to thoracotomy due to the adhesions. The influences of pleural adhesions on the perioperative period were comparatively large under following conditions (level-A); the adhesion-type was tight which meant lung and pleural wall sticked closely even if lung collapse was encouraged, the strength was middle( required sharp-dissection) or strong( hard to dissect between visceral and parietal pleura), and the range was more than 10% of total pleural surface. Significant influences of the level-A of pleural adhesions were as follows;prolonged operation time in all procedures, frequent intraoperative lung fistula and prolonged pleural drainage period in wedge resections, and increased blood loss, intraoperative and postoperative lung fistula with prolonged pleural drainage time and postoperative hospitalization period in lobectomy. Other postoperative complications (pneumonia, empyema, exacerbation of interstitial pneumonitis, and arrhythmias) were not associated with pleural adhesions. Careful dissection procedure for pleural adhesions that minimize damage of visceral pleura would be the most important.

Risk factors of middle lobe bronchus kinking following right upper lobectomy.

BACKGROUND: The incidence rate of kinking of the middle lobe bronchus following right upper lobectomy is higher compared to that with residual lung bronchus following other lobectomies. Bronchial kinking was presumed to be caused by the displacement of the residual lung lobes, but its etiology is unclear. Moreover, prevention methods and effective treatments have not yet been established. The purpose of this study was to investigate the risk factors and etiology of middle lobe bronchus kinking and discuss prevention methods. METHODS: Patients who underwent right upper lobectomy in our hospital were retrospectively evaluated. Patient clinical characteristics, lung function, and lung lobe volume, surgical procedure were analyzed in association with the incidence of middle lobe bronchus kinking. The association between the displacement of residual lung lobes after operation and the incidence of middle lobe bronchus kinking was analyzed to assess the etiology. RESULTS: A total of 175 patients were enrolled in the risk analysis. Middle lobe bronchus kinking was observed in 5 patients (2.9%). The low percentage of forced expiratory volume percentage in 1 second (P=0.021), the low volume ratio of the right middle lobe (RML) to the right thoracic cavity (RTC) (P=0.016), and the low volume ratio of RML to right upper lobe (RML/RUL) (P=0.006) were significant risk factors of middle lobe bronchus kinking. In the patients who underwent CT at 6 months after surgery, the degree of the cranial displacement of RML was associated with the incidence of middle lobe bronchus kinking (P=0.025). CONCLUSIONS: The risk of middle lobe bronchus kinking could be assessed preoperatively by calculating the volume ratio of RML/RTC and RML/RUL. The displacement of RML could be associated with the incidence of middle lobe bronchus kinking.