Investigation of an Optimal Material Addition Rate for Energy Consumption and Dimensional Accuracy in Fused Filament Fabrication of CFR-PEEK.

The material addition rate (MAR) of fused filament fabrication (FFF) is an indicator of process efficiency varied by process parameter settings, which affects energy consumption and part quality in FFF. This study aims to identify the optimal MAR of FFF using carbon-fiber-reinforced polyether-ether-ketone (CFR-PEEK) by considering a trade-off between energy consumption and the dimensional accuracy of FFF outputs. A design of experiments considering two main process parameters is planned to print three sample types through FFF for CFR-PEEK. Then, the MAR (i.e., deposited material volume per build time) of FFF is obtained to derive individual regression models of energy consumption and the dimensional accuracy measured for each sample type. Furthermore, a trade-off between energy consumption and dimensional accuracy on the MAR is formulated to derive an optimal MAR for each sample type. The results show that FFF for CFR-PEEK has a trade-off between energy consumption and dimensional accuracy; there exists a specific MAR that maximizes the overall performance of energy consumption and dimensional accuracy for each sample type. The optimal MAR is the highest for the small volume sample, whereas it becomes the lowest for the vertical build orientation sample. This study suggests that the optimal MAR should be flexibly adjusted based on a fabricated part. The findings from this study also address the fact that decision-making for optimal FFF operations needs a transition from the identification of specific process parameter settings to the management of a proper process efficiency level in FFF.

Significance of histologic subtype size as a prognostic indicator in stage IA lung adenocarcinoma.

Background: Predicting prognosis is complex due to a unique characteristic in stage IA lung adenocarcinoma. The feature indicated heterogeneous histologic subtype and ground glass opacity (GGO). Many studies demonstrated different prognoses according to histologic subtype or non-GGO lesion. This study aimed to evaluate the clinical outcomes following each histologic subtype size in stage IA lung adenocarcinoma and identify the prognostic impact of each histologic subtype size. Methods: The medical records of 550 patients with pathological stage IA lung adenocarcinoma were reviewed. Histologic subtype size was estimated by multiplying the tumor's maximum diameter by the proportion of each histologic subtype. Univariate and multivariate analyses were conducted to identify the prognostic role of each histologic subtype size in stage IA lung adenocarcinoma. Results: The median age and tumor size were 63 [25-82] years and 1.8 [0.3-3] cm, respectively. Acinar (42.0%) and lepidic (44.4%) were the most common among the predominant subtype. Each subtype size was estimated and re-categorized following the current staging system. The disease-free interval (DFI) was significantly different following each histologic subtype size. Multivariate analysis for DFI revealed more acinar, micropapillary, and solid subtypes and fewer lepidic subtypes with worse prognoses. Conclusions: The prognosis for DFI is determined through a complex process by various variables in stage IA lung adenocarcinoma. Each subtype size has a more prognostic impact than the predominant subtype.

Successful Endoscopic Vacuum Therapy for Extensive Gastric Tubing Necrosis after Ivor-Lewis Esophagectomy: A Case Report.

The stomach has become the most commonly used site for grafts to replace the esophagus in esophageal cancer surgery because of its good blood supply and ability to enable single-reconstruction anastomosis. However, anastomotic failure is a serious complication after esophageal cancer surgery. Unlike anastomotic leakage due to local ischemia, gastric tube necrosis is a life-threatening condition with a high mortality rate. Gastric tube necrosis involves extensive ischemia due to a decreased blood supply, and an urgent operation is mandatory in most cases. Endoscopic vacuum therapy (EVT) has been used for anastomotic leakage after esophageal surgery. In recent years, it has been successfully used for more extensive disease, including large esophageal perforation as an indication for reoperation. Hence, we report a case of extensive gastric tube necrosis treated by EVT after an Ivor Lewis operation.

Comparison of clinical results between high grade patterns in stage I lung adenocarcinoma.

BACKGROUND: The histological subtype has been introduced in invasive lung adenocarcinoma. The predominant micropapillary and solid subtypes are categorized as high-grade patterns and provide a worse prognosis. However, the prognostic analysis of high-grade patterns has not previously been fully investigated. Thus, this study aimed to investigate the prognostic role of high-grade patterns in pathological stage I lung adenocarcinoma. METHODS: Patients with stage I lung adenocarcinoma and micropapillary or solid components were reviewed. Clinicopathological features and clinical course were compared in these subtypes, and prognostic factors were analyzed in high-grade patterns. RESULTS: The patients were classified into five groups based on the presence of micropapillary or solid subtypes, namely, micropapillary predominant, solid predominant, both nonpredominant subtypes, only minor micropapillary subtype, and only minor solid subtype present. Disease-free interval was significantly different, and the micropapillary predominant group showed worse disease-free interval (p = 0.001). Contrastingly, the solid predominant group showed significantly worse overall survival among high-grade patterns (p = 0.035). The multivariate analysis revealed an association between smoking, micropapillary predominant, blood vessel invasion, and visceral pleural invasion with recurrence and more association between solid predominant and visceral pleural invasion with overall survival. CONCLUSIONS: Clinical results were different in stage I high-grade adenocarcinoma. The predominant micropapillary subtype is the independent prognostic factor for recurrence. However, the solid subtype is the significant factor for overall survival. Furthermore, the predominant subtype is the most valuable and independent prognostic factor for predicting recurrence or survival.

Predicting prognosis using a pathological tumor cell proportion in stage I lung adenocarcinoma.

BACKGROUND: Tumor size is a valuable prognostic factor because it is considered a measure of tumor burden. However, it is not always correlated with the tumor burden. This study aimed to identify the prognostic role of pathological tumor proportional size using the proportion of tumor cells on the pathologic report after curative resection in pathologic stage I lung adenocarcinoma. METHODS: We retrospectively reviewed the medical records of 630 patients with pathologic stage I lung adenocarcinoma after lung resection for curative aims. According to the pathologic data, the proportion of tumor cells was reviewed and pathological tumor proportional size was estimated by multiplying the maximal diameter of the tumor by the proportion of tumor cells. We investigated the prognostic role of pathological tumor proportional size. RESULTS: The median tumor size was 2 cm (range: 0.3-4), and the median pathological tumor proportional size was 1.5 (range: 0.12-3.8). This value was recategorized according to the current tumor-node-metastasis (TNM) classification, and 184 patients showed down staging compared with the current stage. The survival curve for disease-free survival using pathological tumor proportional size showed more distinction than the current stage classification. Multivariate analysis revealed that a down stage indicated a favorable prognostic factor. CONCLUSION: Pathological tumor cell proportional size may be associated with prognosis in stage I lung adenocarcinoma. If the pathological tumor proportional size shows a downward stage, it may indicate a smaller tumor burden and better prognosis.

Simulating energy consumption based on material addition rates for material extrusion of CFR-PEEK: a trade-off between energy costs and cycle time.

While many studies for material extrusion-based additive manufacturing (AM) of polymers focus on experimental approaches to evaluate relevant performance measures from process parameters, there is a lack of discussion to connect experimental results with useful applications. Also, one of the major deficiencies in the application literature is a trade-off analysis between energy costs and cycle time (time to produce an item from the beginning to the end) since improving these two measures simultaneously is challenging. Thus, this paper proposes an energy simulation method for performing a trade-off analysis between energy costs and cycle time using combinations of major AM process parameters for material extrusion. We conduct experiments using carbon fiber-reinforced poly-ether-ether-ketone (CFR-PEEK), which is increasingly used in material extrusion. From experimental results, we build a power model in which power (kW) is derived as a linear function of material addition rates (MAR). This MAR regression model is then used in a proposed simulation model that integrates discrete event simulation and numerical simulation. In our simulation case study of 50 machines and 40 scenarios, we investigate trade-offs between energy costs and cycle time with three control policies (P1, P25, and P50) that allow 1, 25, or 50 machines to start heating, respectively. The trade-off analysis results show that P25 can be preferred when a balance between cycle time and energy costs is pursued, while P1 or P50 can be chosen if either energy cost (with P1) or cycle time (with P50) is more important than the other measure. Moreover, we find that the machine utilization, variability, and product volume have significant effects on energy costs and cycle time.

Prognostic impact according to the proportion of the lepidic subtype in stage IA acinar-predominant lung adenocarcinoma.

BACKGROUND: Adenocarcinoma is the most common type of lung cancer and most adenocarcinomas have heterogeneous subtypes. Acinar-predominant adenocarcinoma is the most common. This study aimed to identify the prognostic impact of other mixed histological subtypes in acinar-predominant lung adenocarcinoma. METHODS: The medical records of patients with pathological stage IA acinar-predominant lung adenocarcinoma between January 2010 and April 2016 were reviewed. The patients were divided into two groups according to the proportion of the lepidic subtype, with a cutoff value of 20%, and prognostic factors were analyzed. RESULTS: A total of 215 patients with stage IA acinar-predominant adenocarcinoma were reviewed. The 20% or more lepidic subtype group had a low value of SUVmax (p = 0.001), good differentiation (p < 0.001) and a low incidence of the solid histological subtype (p = 0.016). Recurrence was significantly lower in the 20% or more lepidic subtype group (p = 0.008). The disease-free survival (p = 0.007) and overall survival (p = 0.046) were significantly different between the two groups. Multivariate analysis showed that lymphovascular invasion (p = 0.006) and no or less than 20% lepidic subtype (p = 0.036) were significant prognostic factors for disease-free survival. CONCLUSIONS: The lepidic proportion may be useful to predict recurrence in acinar-predominant stage IA lung adenocarcinoma.

Significant difference in recurrence according to the proportion of high grade patterns in stage IA lung adenocarcinoma.

BACKGROUND: Patients with early lung cancer are the best candidates for surgical resection. However, those patients with high grade patterns (micropapillary or solid) do not have a good prognosis, even if they have been diagnosed with stage I lung adenocarcinoma. A new modified grading system has been introduced and this study aimed to identify the prognostic role of the new grading system in patients with stage IA lung adenocarcinoma. METHODS: Patients with pathological stage IA lung adenocarcinoma, according to the eighth TNM classification who underwent curative resection, were reviewed. The pathological data of stage IA adenocarcinoma was reviewed 1 (grade 1: lepidic predominant with no or less than 20% of high grade patterns, grade 2: acinar or papillary predominant with no or less than 20% of high grade patterns, grade 3: any tumor with 20% or more of high grade patterns). Prognostic factors were analyzed for disease-free interval (DFI) and overall survival (OS) using Cox proportional models. RESULTS: The medical records of 429 patients with stage IA lung adenocarcinoma were reviewed. DFI (p < 0.001) and OS (p < 0.001) were significantly lower in patients diagnosed with grade 3 compared with grade 1 and grade 2. Multivariate analysis showed that smoking (p = 0.013), value of SUVmax (p = 0.005), lymphovascular invasion (p = 0.004) and grade 3 (p = 0.008) were significant prognostic factors for DFI. CONCLUSIONS: The proportion of high grade patterns showed a different prognosis, even if curative resection had been performed for stage IA adenocarcinoma. This new grading system is more simple and useful in the prediction of a prognosis in patients with stage IA lung adenocarcinoma.

Industrial Energy Assessment Training Effectiveness Evaluation: An Eye-Tracking Study.

It is essential to understand the effectiveness of any training program so it can be improved accordingly. Various studies have applied standard metrics for the evaluation of visual behavior to recognize the areas of interest that attract individuals' attention as there is a high correlation between attentional behavior and where one is focusing on. However, through reviewing the literature, we believe that studies that applied eye-tracking technologies for training purposes are still limited, especially in the industrial energy assessment training field. In this paper, the effectiveness of industrial energy assessment training was quantitatively evaluated by measuring the attentional allocation of trainees using eye-tracking technology. Moreover, this study identifies the areas that require more focus based on evaluating the performance of subjects after receiving the training. Additionally, this research was conducted in a controlled environment to remove the distractions that may be caused by environmental factors to only concentrate on variables that influence the learning behavior of subjects. The experiment results showed that after receiving the training, the subjects' performance in energy assessment was significantly improved in two areas: production, and recycling and waste management, and the designed training program enhanced the knowledge of participants in identifying energy-saving opportunities to the knowledge level of experienced participants.

Prediction Model for Airborne Microorganisms Using Particle Number Concentration as Surrogate Markers in Hospital Environment.

Indoor microbiological air quality, including airborne bacteria and fungi, is associated with hospital-acquired infections (HAIs) and emerging as an environmental issue in hospital environment. Many studies have been carried out based on culture-based methods to evaluate bioaerosol level. However, conventional biomonitoring requires laborious process and specialists, and cannot provide data quickly. In order to assess the concentration of bioaerosol in real-time, particles were subdivided according to the aerodynamic diameter for surrogate measurement. Particle number concentration (PNC) and meteorological conditions selected by analyzing the correlation with bioaerosol were included in the prediction model, and the forecast accuracy of each model was evaluated by the mean absolute percentage error (MAPE). The prediction model for airborne bacteria demonstrated highly accurate prediction (R2 = 0.804, MAPE = 8.5%) from PNC1-3, PNC3-5, and PNC5-10 as independent variables. Meanwhile, the fungal prediction model showed reasonable, but weak, prediction results (R2 = 0.489, MAPE = 42.5%) with PNC3-5, PNC5-10, PNC > 10, and relative humidity. As a result of external verification, even when the model was applied in a similar hospital environment, the bioaerosol concentration could be sufficiently predicted. The prediction model constructed in this study can be used as a pre-assessment method for monitoring microbial contamination in indoor environments.

Use of imaging studies to predict postoperative recurrences of primary spontaneous pneumothorax.

BACKGROUND: Bullectomy with pleural procedure is the most effective means of treating primary spontaneous pneumothorax (PSP). However, recurrences after thoracoscopic bullectomy are unexpectedly frequent. Our aim was to identify the premonitory imaging features after thoracoscopic bullectomy that may associate with recurrences in PSP. METHODS: The medical records of all patients undergoing thoracoscopic bullectomy for PSP between January 2013 and September 2016 were subject to review. A total of 154 procedures performed on 147 patients qualified for study. Clinical outcomes and characteristics of patients were reviewed and serial chest radiographies were assessed, analyzing risk factors for postoperative recurrences. RESULTS: Median age of the male-predominant cohort (93.5%) was 19 (range, 15-39) years. Median operative time was 35 min, none reflecting complications. Postoperatively, diaphragmatic tenting was identified in 78 patients (50.6%), and pleural residual cavity was identified by chest radiography in 102 (66.2%). After discharge, remained diaphragmatic tenting (38/154, 24.7%) and pleural residual cavity (52/154, 33.8%) were identified by chest radiography. In univariate analysis, remained diaphragmatic tenting (P=0.026) and length of pleural residual cavity (P=0.024) emerged as risk factors for recurrence; and both reached significance in multivariate analysis (P=0.020 and P=0.018, respectively). CONCLUSIONS: Remained diaphragmatic tenting after thoracoscopic surgery for PSP may be associated with the risk of postoperative recurrence.

Should We Consider the Resected Lung Volume in Primary Spontaneous Pneumothorax?

BACKGROUND: Although bullectomy is the most curative treatment in primary spontaneous pneumothorax (PSP), postoperative recurrence is not uncommon. New bulla formation at the staple line is the most common cause of recurrence. However, the mechanism is not known. We believe that the pressure gradient plays the main role in new bulla formation. A large resection amount induces a prolonged pressure gradient for obliteration of the residual space. This study aimed to identify the association between resected lung volume and recurrence. METHODS: The medical records of patients who underwent video-assisted thoracoscopic surgery (VATS) bullectomy were reviewed between October 2010 and December 2017. A total of 396 patients underwent surgery for spontaneous pneumothorax. The electronic medical records (EMRs) of the patients were reviewed. Patients with secondary spontaneous pneumothorax were excluded. Patients who were diagnosed with emphysema on CT were excluded. Patients with PSP were excluded from the study if the bulla was not located in the apex or if there was no ruptured bulla at the time of the operation. Patients who lacked EMRs were also excluded. We reviewed the medical records of 276 patients. The apical resected lung volume was estimated using a conical volumetric formula with the use of the specimen size. The risk factors for postoperative recurrence were analyzed. RESULTS: The median age was 19 years old (range 13-36). A total of 261 patients were male (94.6%). The median body weight and body mass index (BMI) were 58 kg (range 40-82) and 18.92 (range 15.21-26.47), respectively. In 24 patients, both sides were operated on simultaneously. The resected lung volume was obtained by using a conical volumetric formula, and the value was divided by the BMI value. The median value was 1.43 (0.03-5.67). The median operative time was 35 min (range 15-120). The median postoperative day was 4 (range 2-12). Age (p = 0.006), the value of the resected lung volume divided by BMI (p = 0.003), bilateral bullectomy (p = 0.013) and transverse diameter (p = 0.034) were associated with postoperative recurrence according to the univariate analysis. According to the multivariate analysis, age and the value of the lung volume divided by BMI were significant risk factors for postoperative recurrence. CONCLUSIONS: Younger age and a large resected lung volume and a low BMI are associated with postoperative recurrence after VATS bullectomy for PSP.

Effect of histological subtype and treatment modalities on T1-2 N0-1 small cell lung cancer: A population-based study.

BACKGROUND: Combined small cell lung cancer (C-SCLC) is rare and its clinical features, appropriate treatment, and prognosis are poorly understood. Reports conflict over the prognosis of C-SCLCs compared to pure small cell lung cancer. METHODS: The records of patients diagnosed with primary SCLC from 1988 to 2014 were extracted from the Surveillance, Epidemiology, and End Results database. The general features of C-SCLCs were compared to those of SCLCs. T1-2 N0-1 data was extracted and the effects of the histological subtype, treatment modality, and other prognostic factors on lung cancer-specific survival (CSS) was analyzed in a 3:1 matched dataset. Analysis was performed using the 8th edition tumor node metastasis staging system and previous staging systems adjunctively. RESULTS: C-SCLCs comprised 1.5% of all SCLCs (1486/98 667); 184 cases of C-SCLCs and 2681 cases of non-combined SCLCs (NC-SCLCs) were included in this study. C-SCLCs were more likely to be of a higher grade and to occur in the upper lobe than NC-SCLCs. Before matching, C-SCLCs showed better CSS (hazard ratio 0.69; P < 0.001). However, stratified Cox proportional hazards analysis in the matched dataset revealed that only treatment modality and age at diagnosis were associated with CSS; the histological subtype had no effect on survival. Of all treatment modalities, surgery with chemoradiation showed the best CSS in T1-2 N0-1 SCLC. CONCLUSION: In early SCLC, surgery with chemoradiation shows the best CSS. C-SCLC patients might benefit more from multimodal treatments, including surgery, than SCLC patients.

Successful thoracoscopic resection of a large mediastinal angiomyolipoma.

An angiomyolipoma (AML) is a benign mesenchymal tumor characterized by proliferation of mature vessels, smooth muscle, and adipose tissue. AMLs most commonly occur in the kidney but have been reported in a variety of extrarenal sites. Mediastinal AMLs are extremely rare. We herein present a case of a large AML of the mediastinum that was successfully treated by thoracoscopic resection.

When Is the Optimal Timing of the Surgical Treatment for Secondary Spontaneous Pneumothorax?

Objectives The definition of spontaneous pneumothorax is accumulation of air in the pleural space, resulting in dyspnea or chest pain. Unlike primary spontaneous pneumothorax, secondary pneumothorax can be a life-threatening condition and spontaneous healing rate is uncommon. Although surgery is the most effective treatment modality for pneumothorax, surgical management and timing is difficult where there is underlying lung disease and/or medical comorbidities. Prolonged air leakage increases the morbidity and mortality in thoracic surgery. We hypothesized that duration of air leakage before operation may lead to increase in complications. Methods This study is a retrospective review of 155 consecutive patients with air leakage who underwent bullectomy for secondary spontaneous pneumothorax from January 2005 to July 2013. The patients were divided according to the duration of preoperative air leakage. The patients were followed-up until the time of last visit or death. Postoperative morbidity and mortality were assessed and the risk factors for complications were analyzed. Results The median age was 65 years (range, 52-88) with male predominance (96.13%). The median duration of preoperative air leakage was 6 days (range, 1-30). The median surgery time was 90 minutes (range, 25-300) and median hospital stay after operation was 7 days (range, 3-75). Postoperative complications occurred in 38 patients (24.52%) and postoperative recurrence was shown to have occurred in 8 patients (5.16%). With multivariate analysis, risk factors for postoperative complications were: underlying interstitial lung disease and air leakage > 5 days before operation. Conclusion Persistent air leakage was a major surgical indication for pneumothorax. Early surgical treatment reduced postoperative complications for secondary spontaneous pneumothorax.

Does oxygen therapy increase the resolution rate of primary spontaneous pneumothorax?

BACKGROUND: Patients with small pneumothoraces are usually treated with oxygen therapy. However, evidence that oxygen therapy increases resolution rate is based on small populations with secondary spontaneous pneumothorax. Therefore, this study aimed to confirm whether oxygen therapy increases the resolution rate of primary spontaneous pneumothorax (PSP). METHODS: We retrospectively reviewed records of patients with PSP who had undergone outpatient observation (room air group) and those who were admitted for oxygen therapy (O2 group) between March 2005 and February 2016. The initial chest posteroanterior (PA) radiograph was compared with the last chest PA radiograph before the pneumothorax disappeared. The size of the pneumothorax was measured using the Collins' method. RESULTS: A total of 175 episodes were identified in 160 patients. Of these, 128 episodes (73.1%) occurred in patients in the O2 group. The mean age was 19.24±4.74 years. The mean initial size of the pneumothorax was smaller in the room air group (23.32%±7.00% vs. 20.26%±6.78%, P=0.011). The resolution rate was higher in the O2 group [(4.27%±1.97%) vs. (2.06%±0.97%)/day, P<0.001]. The initial size of the pneumothorax, time interval between radiographs, and use of oxygen therapy were significantly associated with the resolution rate in multivariate analysis. CONCLUSIONS: Oxygen therapy increases the resolution rate of PSP. However, routine use of oxygen therapy in patients with small pneumothoraces should be considered more carefully. Well-controlled prospective studies are required to confirm the indication of oxygen therapy.

Does 11.5 mm guided single port surgery has clinical advantage than multi-port thoracoscopic surgery in spontaneous pneumothorax?

BACKGROUND: Video-assisted thoracoscopic surgery (VATS) has been widely used for spontaneous pneumothorax (SP). In recent years, thoracic surgeons have attempted single incision or single port surgery with the development of surgical technology and skills. Theoretically, single port surgery is expected to provide benefits such as less pain and early recovery. The purpose of this study was to determine the benefits of single port surgery in SP. METHODS: The 107 patients with SP who underwent surgery, between July 2013 and May 2015, were reviewed retrospectively. The patients with secondary pneumothorax, who underwent open procedures and lacking of medical records were excluded. Visual analog scale (VAS), paresthesia and clinical outcomes were reviewed in 86 patients (46 patients: three-port, 40 patients: 11.5 mm guided single-port). RESULTS: The mean age was 23.4 years in three-port and 22.4 in single-port (P=0.247). The height and body weight were not significantly difference between two groups. The mean operation time was 39 minutes (mins) in the three-port and 37.3 mins in the single port without statistical difference (P=0.204). The pain score in the single port surgery was significantly lower after postoperative day (POD) 1 (P=0.028). However chest tube duration time was significantly shorter in the single port group (P<0.001). After exclusion of the patients with chest tube removal within postoperative 1 day, the pain score was not significantly different at the POD 1 between two groups (P=0.176). The pain score between two groups were not different at 1 week after discharge. CONCLUSIONS: The pain score reduction was found 1 day after operation in the single port group. However, the chest tube duration time was significantly shorter in the single port group and the pain score was not different at 1 week after discharge. Considering young age in primary SP, the benefit of single port surgery in SP was minimal.

High Intrathoracic Anastomosis with Thoracoscopy Is Safe and Feasible for Treatment of Esophageal Squamous Cell Carcinoma.

BACKGROUND: Minimally invasive esophagectomy (MIE) has the potential to reduce the morbidity and mortality of esophageal cancer surgery. Esophageal squamous cell carcinoma (ESCC) has a high incidence of earlier lymphatic spread and is usually located more proximal to the incisor than esophageal adenocarcinoma; consequently, the anastomosis should be made more proximal in the thorax or in the neck. We adopted the proximal intrathoracic anastomotic technique using thoracoscopy for mid-to-lower ESCC. METHODS: From October 2010 to August 2014, fifty-eight consecutive patients underwent MIE for ESCC. After laparoscopic gastric tubing, thoracoscopic esophageal resection and reconstruction were performed using a 28-mm circular stapler following radical mediastinal lymph node dissection. We tried to make an anastomosis at the apex of the chest. Postoperative outcomes, including overall survival and recurrence, were assessed. RESULTS: The mean patient age was 64.3±9 years. The mean operative time was 371.8±51.6 minutes, and the duration of the thorax procedure was 254.8±38.3 minutes. The mean number of lymph nodes dissected was 31±11.7. The mean intensive care unit (ICU) stay and hospital stay were 3.5±8.2 hours and 13.6±7.4 days, respectively. The level of anastomosis was 22.3±1.8cm from the incisor. One patient died of uncontrolled sepsis due to necrosis of the gastric graft. Two patients developed small contained leakage. Nine patients exhibited distant metastasis during the follow-up period. CONCLUSION: Thoracoscopic intrathoracic anastomosis at the proximal esophagus is feasible and safe.

Air leakage on the postoperative day: powerful factor of postoperative recurrence after thoracoscopic bullectomy.

BACKGROUND: Primary spontaneous pneumothorax (PSP) is a relatively common disorder in young patients. Although various surgical techniques have been introduced, recurrence after video-assisted thoracoscopic surgery (VATS) remains high. The aim of study was to identify the risk factors for postoperative recurrence after thoracoscopic bullectomy in the spontaneous pneumothorax. METHODS: From January 2011 through March 2013, two hundreds and thirty two patients underwent surgery because of pneumothorax. Patients with a secondary pneumothorax, as well as cases of single port surgery, an open procedure, additional pleural procedure (pleurectomy, pleural abrasion) or lack of medical records were excluded. The records of 147 patients with PSP undergoing 3-port video-assisted thoracoscopic bullectomy with staple line coverage using an absorbable polyglycolic acid (PGA) sheet were retrospectively reviewed. RESULTS: The median age was 19 years (range, 11-34 years) with male predominance (87.8%). Median postoperative hospital stay was 3 days (range, 1-10 days) without mortality. Complications were developed in five patients. A total of 24 patients showed postoperative recurrence (16.3%). Younger age less than 17 years old and immediate postoperative air leakage were risk factors for postoperative recurrence after thoracoscopic bullectomy by multivariate analysis. CONCLUSIONS: Immediate postoperative air leakage was the risk factor for postoperative recurrence. However, further study will be required for the correlation of air leakage with recurrence.