Surgeon Perspectives on Anastomotic Leaks and FluidAI’s StreamTM Platform: Integrating Qualitative Insights for Technological Innovation

Purpose: This article investigates the critical importance of integrating surgeons’ direct input into the development of innovative technologies that address gaps in surgical care, including those aimed at reducing anastomotic leaks (AL), a major complication in gastrointestinal surgery. While traditional quantitative research methods are prevalent, they often overlook the invaluable insights of the surgeons who manage these complications firsthand. Subjects and Methods: This study employs a qualitative approach, utilizing semi-structured interviews with 40 surgeons from various specialties, including general, bariatric, colorectal, trauma, hepato-biliary, and thoracic surgery. The interviews were designed to probe the needs of surgeons, challenges currently faced, and gaps in clinical practice, research, and technology for detection and/or management of AL. The data were analyzed using thematic analysis, which revealed significant gaps in current technologies for early detection and prevention of leaks. Results: Surgeons expressed strong interest in FluidAI’s Stream™ Platform, a non-invasive medical device designed to monitor postoperative drainage fluid in real-time, providing continuous data on AL risk. The ability of this platform to offer early prediction through pH and electrical conductivity analysis was particularly appealing to participants, who emphasized the importance of timely interventions in improving patient outcomes. The study’s findings highlight not only the clinical challenges but also the emotional toll that AL takes on surgeons, underlining the need for innovations that are both data-driven and humanistic. Conclusion: By centering surgeons’ perspectives, this research advocates for a human-centered approach to technological advancement, ensuring that new tools are both clinically effective and aligned with the real-world needs of surgical practitioners.

Construction and validation of a risk-prediction model for anastomotic leakage after radical gastrectomy: A cohort study in China

Objectives:Anastomotic leakage(AL)stands out as a prevalent and severe complication following gastric cancer surgery.It frequently precipitates additional serious complications,significantly influencing the overall survival time of patients.This study aims to enhance the risk-assessment strategy for AL following gastrectomy for gastric cancer.Methods:This study included a derivation cohort and validation cohort.The derivation cohort included patients who underwent radical gastrectomy at Sir Run Run Shaw Hospital,Zhejiang University School of Medicine,from January 1,2015 to December 31,2020.An evidence-based predictor questionnaire was crafted through extensive literature review and panel discussions.Based on the questionnaire,inpatient data were collected to form a model-derivation cohort.This cohort underwent both univariate and multivariate analyses to identify factors associated with AL events,and a logistic regression model with stepwise regression was developed.A 5-fold cross-validation ensured model reliability.The validation cohort included patients from August 1,2021 to December 31,2021 at the same hospital.Using the same imputation method,we organized the validation-queue data.We then employed the risk-prediction model constructed in the earlier phase of the study to predict the risk of AL in the subjects included in the validation queue.We compared the predictions with the actual occurrence,and evaluated the external validation performance of the model using model-evaluation indicators such as the area under the receiver operating characteristic curve(AUROC),Brier score,and calibration curve.Results:The derivation cohort included 1377 patients,and the validation cohort included 131 patients.The independent predictors of AL after radical gastrectomy included age65 y,preoperative albumin<35 g/L,resection extent,operative time240 min,and intraoperative blood loss90 mL.The predictive model exhibited a solid AUROC of 0.750(95%CI:0.694e0.806;p<0.001)with a Brier score of 0.049.The 5-fold cross-validation confirmed these findings with a calibrated C-index of 0.749 and an average Brier score of 0.052.External validation showed an AUROC of 0.723(95%CI:0.564e0.882;p?0.006)and a Brier score of 0.055,confirming reliability in different clinical settings.Conclusions:We successfully developed a risk-prediction model for AL following radical gastrectomy.This tool will aid healthcare professionals in anticipating AL,potentially reducing unnecessary interventions.

Preoperative neutrophil-to-lymphocyte ratio predicts symptomatic anastomotic leakage in elderly colon cancer patients: Multicenter propensity score-matched analysis

BACKGROUND The neutrophil-to-lymphocyte ratio(NLR),a composite inflammatory biomarker,is associated with the prognosis in patients with colorectal tumors.However,whether the NLR can be used as a predictor of symptomatic postoperative ana-stomotic leakage(AL)in elderly patients with colon cancer is unclear.AIM To assess the role of the NLR in predicting the occurrence of symptomatic AL after surgery in elderly patients with colon cancer.METHODS Data from elderly colon cancer patients who underwent elective radical colectomy with anastomosis at three centers between 2018 and 2022 were retrospectively analyzed.Receiver operating characteristic curve analysis was performed to determine the best predictive cutoff value for the NLR.Twenty-two covariates were matched using a 1:1 propensity score matching method,and univariate and multivariate logistic regression analyses were used to determine risk factors for the development of postoperative AL.RESULTS Of the 577 patients included,36(6.2%)had symptomatic AL.The optimal cutoff value of the NLR for predicting AL was 2.66.After propensity score matching,the incidence of AL was significantly greater in the≥2.66 NLR subgroup than in the<2.66 NLR subgroup(11.5%vs 2.5%;P=0.012).Univariate logistic regression analysis revealed statistically significant correlations between blood transfusion intraoperatively and within 2 d postoper-atively,preoperative albumin concentration,preoperative prognostic nutritional index,and preoperative NLR and AL occurrence(P<0.05);multivariate logistic regression analysis revealed that an NLR≥2.66[odds ratio(OR)=5.51;95%confidence interval(CI):1.50-20.26;P=0.010]and blood transfusion intraoperatively and within 2 d postoperatively(OR=2.52;95%CI:0.88-7.25;P=0.049)were risk factors for the occurrence of symptomatic AL.CONCLUSION A preoperative NLR≥2.66 and blood transfusion intraoperatively and within 2 d postoperatively are associated with a higher incidence of postoperative symptomatic AL in elderly patients with colon cancer.The preoperative NLR has predictive value for postoperative symptomatic AL after elective surgery in elderly patients with colon cancer.

Impact of open hepatectomy on postoperative bile leakage in patients with biliary tract cancer

BACKGROUND Bile leakage is a common and serious complication of open hepatectomy for the treatment of biliary tract cancer.AIM To evaluate the incidence,risk factors,and management of bile leakage after open hepatectomy in patients with biliary tract cancer.METHODS We retrospectively analyzed 120 patients who underwent open hepatectomy for biliary tract cancer from February 2018 to February 2023.Bile leak was defined as bile drainage from the surgical site or drain or the presence of a biloma on imaging.The incidence,severity,timing,location,and treatment of the bile leaks were recorded.The risk factors for bile leakage were analyzed using univariate and multivariate logistic regression analyses.RESULTS The incidence of bile leak was 16.7%(20/120),and most cases were grade A(75%,15/20)according to the International Study Group of Liver Surgery classification.The median time of onset was 5 d(range,1-14 d),and the median duration was 7 d(range,2-28 d).The most common location of bile leakage was the cut surface of the liver(70%,14/20),followed by the anastomosis site(25%,5/20)and the cystic duct stump(5%,1/20).Most bile leaks were treated conservatively with drainage,antibiotics,and nutritional support(85%,17/20),whereas some required endoscopic retrograde cholangiopancreatography with stenting(10%,2/20)or percutaneous transhepatic cholangiography with drainage(5%,1/20).Risk factors for bile leakage include male sex,hepatocellular carcinoma,major hepatectomy,blood loss,and blood transfusion.CONCLUSION Bile leakage is a frequent complication of open hepatectomy for biliary tract cancer.However,most cases are mild and can be conservatively managed.Male sex,hepatocellular carcinoma,major hepatectomy,blood loss,and blood transfusion were associated with an increased risk of bile leak.

Endoscopic ultrasound-guided tissue sampling induced pancreatic duct leak resolved by the placement of a pancreatic stent:A case report

BACKGROUND Pancreatic ductal leaks complicated by endoscopic ultrasonography-guided tissue sampling(EUS-TS)can manifest as acute pancreatitis.CASE SUMMARY A 63-year-old man presented with persistent abdominal pain and weight loss.Diagnosis:Laboratory findings revealed elevated carbohydrate antigen 19-9(5920 U/mL)and carcinoembryonic antigen(23.7 ng/mL)levels.Magnetic resonance imaging of the pancreas revealed an approximately 3 cm ill-defined space-occupying lesion in the inferior aspect of the head,with severe encasement of the superior mesenteric artery.Pancreatic ductal adenocarcinoma was confirmed after pathological examination of specimens obtained by EUS-TS using the fanning method.Interventions and outcomes:The following day,the patient experienced severe abdominal pain with high amylase(265 U/L)and lipase(1173 U/L)levels.Computed tomography of the abdomen revealed edematous wall thickening of the second portion of the duodenum with adjacent fluid collections and a suspicious leak from either the distal common bile duct or the main pancreatic duct in the head.Endoscopic retrograde cholangiopancreatography revealed dye leakage in the head of the main pancreatic duct.Therefore,a 5F 7 cm linear plastic stent was deployed into the pancreatic duct to divert the pancreatic juice.The patient’s abdominal pain improved immediately after pancreatic stent insertion,and amylase and lipase levels normalized within a week.Neoadjuvant chemotherapy was then initiated.CONCLUSION Using the fanning method in EUS-TS can inadvertently cause damage to the pancreatic duct and may lead to clinically significant pancreatitis.Placing a pancreatic stent may immediately resolve acute pancreatitis and shorten the waiting time for curative therapy.When using the fanning method during EUSTS,ductal structures should be excluded to prevent pancreatic ductal leakage.

Sinusoidal FM Fuze's Channel Leak and Its Jamming Mechanism

Aim To get the theory base of designing FM fuze's jamming signal, its jamming mechanism was studied. Methods A sinusoidal FM fuze was analyzed in time domain and frequency domain and the concept of channel leak was presented. Results It was proved that information channel leak exists in FM fuze because of the nonlinear property of the mixer. The jamming signal was designed based on the channel leak and the jamming mechanism was analyzed in detail. Conclusion This kind of jamming signal can jam the sinusoidal FM fuzes effectively just depending on the jamming signal's feature itself. It's different from the traditional jamming way of simulating echo. Though the sinusoidal FM fuze was just analyzed, the principle is applicable to all FM fuzes. At the same time, it may be used as the reference for FM radar and communication countermeasures.

基于LEAK软件对液氯制取系统中装置泄漏概率的预测研究

氯碱厂液氯制取系统是一个密封性的循环系统,循环介质为液氯及氯气,一旦发生泄漏将造成人员中毒,危及到作业人员的身体健康。为定量计算氯气液化装置的泄漏概率,以某氯碱厂液氯制取系统中装置为研究对象,运用挪威船级社(DNV)的设备同类失效概率数据库,利用LEAK软件,以泄漏源工况为主要随机性因素,通过辨识研究装置中气体泄漏危险源、构建装置泄漏定量预测模型、修正相关系数,进而对氯气液化装置的泄漏概率进行了模拟计算,得出装置可能的泄漏位置和泄漏概率,可为化工企业安全管理提供指导。

使用Visual Leak Detector检测c/c++程序内存泄漏

针对内存泄漏检测问题,本文通过示例说明使用软件Visual Leak Detector来检测泄漏点的方法。通过实验说明该方法在检测一般的c/c++程序内存泄漏时,可以提高检测效率。

PHAST＆LEAK软件在原油中转站事故后果评价中的应用

分析了原油中转站的危险特性,以及可能发生的潜在的火灾、爆炸等危险事故。在分析了原油中转站的设备布置、介质的性质以及场站的人员分布情况的基础上,参照国外部分国家采用的个人风险值和社会风险值,运用PHAST＆LEAK软件对原油中转站进行了整体的风险评价,得出了该场站的油气泄漏火灾爆炸风险水平,对该站的安全运营提供了很好的指导作用。

Endoscopic management of gastrointestinal perforations, leaks and fistulas

Gastrointestinal perforations, leaks and fistulas may be serious and life-threatening. The increasing number of endoscopic procedures with a high risk of perforation and the increasing incidence of leakage associated with bariatric operations call for a minimally invasive treatment for these complications. The therapeutic approach can vary greatly depending on the size,location, and timing of gastrointestinal wall defect recognition. Some asymptomatic patients can be treated conservatively, while patients with septic symptoms or cardio-pulmonary insufficiency may require intensive care and urgent surgical treatment.However, most gastrointestinal wall defects can be satisfactorily treated by endoscopy. Although the initial endoscopic closure rates of chronic fistulas is very high, the long-term results of these treatments remain a clinical problem. The efficacy of endoscopic therapy depends on several factors and the best mode of treatment will depend on a precise localization of the site, the extent of the leak and the endoscopic appearance of the lesion. Many endoscopic tools for effective closure of gastrointestinal wall defects are currently available. In this review, we summarized the basic principles of the management of acute iatrogenic perforations, as well as of postoperative leaks and chronic fistulas of the gastrointestinal tract. We also described the effectiveness of various endoscopic methods based on current research and our experience.

Management of low colorectal anastomotic leak:Preserving the anastomosis

Anastomotic leak continues to be a dreaded complication after colorectal surgery, especially in the low colorectal or coloanal anastomosis. However, there has been no consensus on the management of the low colorectal anastomotic leak. Currently operative procedures are reserved for patients with frank purulent or feculent peritonitis and unstable vital signs, and vary from simple fecal diversion with drainage to resection of the anastomosis and closure of the rectal stump with end colostomy(Hartmann's procedure). However, if the patient is stable, and the leak is identified days or even weeks postoperatively, less aggressive therapeutic measures may result in healing of the leak and salvage of the anastomosis. Advances in diagnosis and treatment of pelvic collections with percutaneous treatments, and newer methods of endoscopic therapies for the acutely leaking anastomosis, such as use of the endosponge, stents or clips, have greatly reduced the need for surgical intervention in selected cases. Diverting ileostomy, if not already in place, may be considered to reduce fecal contamination. For subclinical leaks or those that persist after the initial surgery, endoluminal approaches such as injection of fibrin sealant, use of endoscopic clips, or transanal closure of the very low anastomosis may be utilized. These newer techniques have variable success rates and must be individualized to the patient, with the goal of treatment being restoration of gastrointestinal continuity and healing of the anastomosis. A review of the treatment of low colorectal anastomotic leaks is presented.

Evaluation of fully covered self-expanding metal stents in benign biliary strictures and bile leaks

AIM: To investigate the use of fully covered metal stents in benign biliary strictures (BBS) and bile leaks. METHODS: We studied 17 patients, at Harbor-UCLA Medical center (Los Angeles), with BBS (n=12) and bile leaks (n=5) from July 2007 to February 2012 that had received placement of fully covered self-expanding metal stents (FCSEMs). Fourteen patients had endoscopic placement of VIABIL (Conmed, Utica, New York, United States) stents and three had Wallflex (Boston Scientific, Mass) stents. FCSEMS were 8 mm or 10 mm in diameter and 4 cm to 10 cm in length. Patients were followed at regular intervals to evaluate for symptoms and liver function tests. FCSEMS were removed after 4 or more weeks. Resolution of BBS and leak was documented cholangiographically following stent removal. Stent patency can be defined as adequate bile and contrast flow from the stent and into the ampulla during endoscopic retrograde cholangiopancreatography (ERCP) without clinical signs and/or symptoms of biliary obstruction. Criterion for bile leak resolution at ERCP is defined as absence of contrast extravasation from the common bile duct, cystic duct remanent, or gall blad-der fossa. Rate of complications such as migration, and instent occlusion were recorded. Failure of endoscopic therapy was defined as persistent biliary stenosis or continuous biliary leakage after 12 mo of stent placement. RESULTS: All 17 patients underwent successful FC- SEMS placement and removal. Etiologies of BBS included: cholecystectomies (n=8), cholelithiasis (n=2), hepatic artery compression (n=1), pancreatitis (n=2), and Whipple procedure (n=1). All bile leaks occurred following cholecystectomy. The anatomic location of BBS varied: distal common bile duct (n=7), common hepatic duct (n=1), hepaticojejunal anastomosis (n=2), right intrahepatic duct (n=1), and choledochoduo-denal anastomatic junction (n=1). All bile leaks were found to be at the cystic duct. Twelve of 17 patients had failed prior stent placement or exchange. Resolution of the biliary strictures and bile leaks was achieved in 16 of 17 patients (94%). The overall median stent time was 63 d (range 27-251 d). The median stent time for the BBS group and bile leak group was 62 ± 58 d (range 27-199 d) and 92 ± 81 d (range 48-251 d), respectively. All 17 patients underwent successful FCSEMS removal. Long term follow-up was obtained for a median of 575 d (range 28-1435 d). Complications occurred in 5 of 17 patients (29%) and included: migration (n=2), stent clogging (n=1), cholangitis (n=1), and sepsis with hepatic abscess (n=1). CONCLUSION: Placement of fully covered self-expanding metal stents may be used in the management of benign biliary strictures and bile leaks with a low rate of complications.

Leake计数器几何响应的研究

研究了不同吸收层结构的Leake计数器的角响应和径向微分响应,结果表明,这些响应与吸收层结构基本无关。并且径向微分响应可用公式ε(P)=(1-((P/r))~2)1/2拟合。

Distinguishing between parenchymal and anastomotic leakage at duct-to-mucosa pancreatic reconstruction in pancreaticoduodenectomy

AIM： To distinguish anastomotic from parenchymal leakage at duct-to-mucosa reconstruction of the pancreatic remnant. METHODS： We reviewed the charts of 68 pancreaticoduodenectomies performed between 5/2000 and 12/2005 with end-to-side duct-to-mucosa pancreatojejunostomy （PJ）. The results of pancreatography, as well as peripancreatic drain volumes, and amylase levels were analyzed. RESULTS： Of 68 pancreatojejunostomies, 48 had no leak by pancreatography and had low-drain amylase （normal）; eight had no pancreatographic leak but had elevated drain amylase （parenchymal leak）; and 12 had pancreatographic leak and elevated drain amylase （anastomotic leak）. Although drain volumes in the parenchymal leak group were significantly elevated at postoperative day （POD） 4, no difference was found at POD 7. Drain amylase level was not significantly different at POD 4. In contrast, at POD 7, the anastomotic-leak group had significantly elevated drain amylase level compared with normal and parenchymalleak groups （14158 ＋ 24083 IU/L vs 89 ＋ 139 IU/L and 1707 ＋ 1515 IU/L, respectively, P = 0.012）. CONCLUSION： For pancreatic remnant reconstruction after pancreaticoduodenectomy, a combination of pancreatogram and peripancreatic drain amylase levels can be used to distinguish between parenchymal and anastomotic leakage at pancreatic remnant reconstruction.

Application of an Improved ISODATA Method to Pipeline Leak Detection

Increasingly serious leak problem in pipeline transportation has not only affected the operation of pipelines but also caused loss of precious resource and environmental damage. Based on the analysis of the occurrence of negative pressure waves and the unsupervised learning of pattern recognition, the Interactive Self-organizing Data Analysis Technique Algorithm （ISODATA） method was used to classify the negative pressure waves and then the states of pipelines could be determined. K L transformation was used to eliminate the correlativity of feature parameters and to reduce the dimensionality of feature vector space to speed up calculation. Experimental results validated the accuracy and practical value of this method.

Pedicled greater omentum flap for preventing bile leak in liver transplantation patients with poor biliary tract conditions

BACKGROUND: Bile leak remains a main complication in liver transplantation patients with poor biliary tract conditions, mainly caused by an insufficient blood supply or dysplasia of the biliary tract. Although Roux-en-Y modus operandi can be adopted, the risk of other complications of the biliary tract such as infection increases. Using pedicled greater omentum flaps to wrap the anastomotic stoma, which increases the biliary tract blood supply, may reduce the incidence of bile leak. METHODS: Fourteen patients undergoing piggy-back liver transplantation and having poor biliary tract conditions were treated with pedicled greater omentum flaps to wrap the anastomotic stoma of the biliary tract. Their clinical data were analyzed retrospectively. RESULTS: Of the 14 patients, only one (7.1%) had a mild bile leak on the 8th day post-operation and fully recovered after symptomatic treatment. The other patients had no biliary complications. CONCLUSIONS: Using pedicled greater omentum flaps to wrap the anastomotic stoma of the biliary tract is an effective way to prevent bile leak in liver transplantation patients, especially those with poor biliary tract conditions. However, experience with this surgical technique still needs to be further explored.

Comparison of two theoretical models for electric leak location at landfill

To solve the disability of conventional model used in electrical leak location when measurement electrodes were buried under the liner, a new model of high voltage DC leak detection is developed. For single-liner landfill, the waste material layer, the geomembrane liner and the soil under the liner are simulated with infinite horizontal layers. The leak is regarded as two parts, one being negative current source at the entrance, and the other positive current source of the same size at the exit. Comparisons between the new theoretical model and conventional model show that conventional model is efficient in locating leaks in geomembane liner associating the dipole scanning above the liner but is ineffective when the measurement electrodes were buried under the liner. The new theoretical model data are in excellent agreement with experimental data not only above the liner but also under the liner.

Anterior resection for rectal carcinoma-risk factors for anastomotic leaks and strictures

AIM:To determine the incidence and factors responsible for anastomotic leaks and stricture following anterior resection(AR)and its subsequent management.METHODS:Retrospective analysis of data from 108 patients with rectal carcinoma who underwent AR or low anterior resection(LAR)to identify the various preoperative,operative,and post operative factors that might have influence on anastomotic leaks and strictures.RESULTS:There were 68 males and 40 females with an average of 47 years(range 21-75 years).The median distance of the tumor from the anal verge was 8 cm(range 3-15 cm).Sixty(55.6%)patients underwent handsewn anastomosis and 48(44.4%)were stapled.The median operating time was 3.5 h(range2.0-7.5 h).Sixteen(14.6%)patients had an anastomotic leak.Among these,11 patients required reexploration and five were managed expectantly.The anastomotic leak rate was similar in patients with and without diverting stoma(8/60,13.4%with stoma and 8/48;16.7%without stoma).In 15(13.9%)patients,resection margins were positive for malignancy.Ninteen(17.6%)patients developed anastomotic strictures at a median duration of 8 mo(range 3-20 mo).Among these,15 patients were successfully managed with per-anal dilatation.On multivariate analysis,advance age(>60 years)was the only risk factor for anastomotic leak(P=0.004).On the other hand,anastomotic leak(P=0.00),mucin positive tumor(P =0.021),and lower rectal growth(P=0.011)were found as risk factors for the development of an anastomotic stricture.CONCLUSION:Advance age is a risk factor for an anastomotic leak.An anastomotic leak,a mucin-secreting tumor,and lower rectal growth predispose patients to develop anastomotic strictures.

Incidence and treatment of mediastinal leakage after esophagectomy:Insights from the multicenter study on mediastinal leaks

BACKGROUND Mediastinal leakage(ML) is one of the most feared complications of esophagectomy. A standard strategy for its diagnosis and treatment has beendifficult to establish because of the great variability in their incidence and mortality rates reported in the existing series.AIM To assess the incidence, predictive factors, treatment, and associated mortality rate of mediastinal leakage using the standardized definition of mediastinal leaks recently proposed by the Esophagectomy Complications Consensus Group(ECCG).METHODS Seven Italian surgical centers(five high-volume, two low-volume) affiliated with the Italian Society for the Study of Esophageal Diseases designed and implemented a retrospective study including all esophagectomies(n = 501) with intrathoracic esophagogastric anastomosis performed from 2014 to 2017.Anastomotic MLs were defined according to the classification recently proposed by the ECCG.RESULTS Fifty-nine cases of ML were recorded, yielding an overall incidence of 11.8%(95%CI: 9.1%-14.9%). The surgical approach significantly influenced the occurrence of ML: the proportion of leakage was 10.5% and 9% after open and hybrid esophagectomy(HE), respectively, and doubled(20%) after totally minimally invasive esophagectomy(TMIE)(P = 0.016). No other predictive factors were found. The 30-and 90-d overall mortality rates were 1.4% and 3.2%,respectively; the 30-and 90-d leak-related mortality rates were 5.1% and 10.2%,respectively; the 90-d mortality rates for TMIE and HE were 5.9% and 1.8%,respectively. Endoscopy was the first-line treatment in 49% of ML cases, with the need for retreatment in 17.2% of cases. Surgery was needed in 44.1% of ML cases.Endoscopic treatment had the lowest mortality rate(6.9%). Removal of the gastric tube with stoma formation was necessary in 8(13.6%) cases.CONCLUSION The incidence of ML after esophagectomy was high mainly in the TMIE group.However, the general and specific(leak-related) mortality rates were low. Early treatment(surgical or endoscopic) of severe leaks is mandatory to limit related mortality.

CFD numerical simulation of dispersion law of indoor gas leakage based on weather conditions

The calculation model was established by k-ε turbulence stress which reflects the change of indoor gas leak's volume fraction,and the CFD software was used to numerically simulate the volume fraction of gas after the gas of continuity leakage,at the same time the changes of gas leak were studied. The results show that the process of gas leakage is different with the change of conditions of indoor and outdoor. Because of the different influencing factors,when the gas leak reaches a certain stable value,the volume fraction,velocity and the explosion of regional are different in the same state indoor. In some regions the gas will explode which meets the fire even if the mean volume fraction of the gas cannot achieve the explosion limit.