Determining optimal fluid and air leak cut off values for chest drain management in general thoracic surgery

PubMed Central

Mesa-Guzman, Miguel; Periklis, Perikleous; Niwaz, Zakiyah; Socci, Laura; Raubenheimer, Hilgardt; Adams, Ben; Gurung, Lokesh; Uzzaman, Mohsin

2015-01-01

Background Chest drain duration is one of the most important influencing aspects of hospital stay but the management is perhaps one of the most variable aspects of thoracic surgical care. The aim of our study is to report outcomes associated with increasing fluid and air leak criteria of protocol based management. Methods A 6-year retrospective analysis of protocolised chest drain management starting in 2007 with a fluid criteria of 3 mL/kg increasing to 7 mL/kg in 2011 to no fluid criteria in 2012, and an air leak criteria of 24 hours without leak till 2012 when digital air leak monitoring was introduced with a criteria of <20 mL/min of air leak for more than 6 hours. Patient data were obtained from electronic hospital records and digital chest films were reviewed to determine the duration of chest tube drainage and post-drain removal complications. Results From 2009 to 2012, 626 consecutive patients underwent thoracic surgery procedures under a single consultant. A total of 160 did not require a chest drain and data was missing in 22, leaving 444 for analysis. The mean age [standard deviation (SD)] was 57±19 years and 272 (61%) were men. There were no differences in the incidence of pneumothoraces (P=0.191), effusion (P=0.344) or re-interventions (P=0.431) for drain re-insertions as progressively permissive criteria were applied. The median drain duration dropped from 1-3 days (P<0.001) and accordingly hospital stay reduced from 4-6 days (P<0.001). Conclusions Our results show that chest drains can be safely removed without fluid criteria and air leak of less than 20 mL/min with median drain duration of 1 day, associated with a reduced length of hospital stay. PMID:26716045

Immunisations and antibiotics in patients with anterior skull base cerebrospinal fluid leaks.

PubMed

Rimmer, J; Belk, C; Lund, V J; Swift, A; White, P

2014-07-01

There are no UK guidelines for the use of antibiotics and/or immunisations in patients with an active anterior skull base cerebrospinal fluid leak. This study aimed to define current UK practice in this area and inform appropriate guidelines for ENT surgeons. A web-based survey of all members of the British Rhinological Society was carried out and the literature in this area was reviewed. Of those who responded to the survey, 14 per cent routinely give prophylactic antibiotics to patients with cerebrospinal fluid leaks, and 34.9 per cent recommend immunisation against at least one organism, most commonly Streptococcus pneumoniae (86.7 per cent). There is no evidence to support the use of antibiotic prophylaxis in patients with a cerebrospinal fluid leak. We propose that all such patients are advised to seek immunisation against pneumococcus, meningococcus and haemophilus.

Vanishing calcification associated with a spontaneous ventral spinal cerebrospinal fluid leak.

PubMed

Schievink, Wouter I; Ross, Lindsey; Prasad, Ravi S; Maya, M Marcel

2016-12-01

Some patients with spontaneous intracranial hypotension have a ventral spinal cerebrospinal fluid (CSF) leak and these CSF leaks may be associated with calcified disk herniations. Identifying these calcifications is helpful in directing treatment. We report here the unusual case of a patient with a ventral CSF leak in whom the associated calcification absorbed over a five-month period. A 42-year-old woman developed orthostatic headaches and bilateral abducens nerve palsies. Magnetic resonance imaging of her brain showed typical findings of spontaneous intracranial hypotension. Magnetic resonance imaging of her spine showed an extensive cervicothoracic CSF leak. Computed tomographic myelography showed calcification at the Th1-2 disk space. Three epidural blood patches were performed, but her symptoms persisted. Digital subtraction myelography performed five months later showed an upper thoracic ventral CSF, but the calcification was no longer present. A dural tear, found at surgery at the Th1-2 level, was repaired and the patient made an uneventful recovery. The resorption of calcifications at the level of a ventral spinal CSF leak could explain the absence of any calcifications in at least some patients with such leaks and demonstrates the usefulness of reviewing previous imaging in patients with ventral CSF leaks if the exact site of the leak remains unknown. © International Headache Society 2016.

Use of duraseal in repair of cerebrospinal fluid leaks.

PubMed

Chin, Christopher J; Kus, Lukas; Rotenberg, Brian W

2010-10-01

The purpose of our article is to review the use of the DuraSeal Sealant System (Confluent Surgical Inc., Waltham, MA) in the repair of complex cerebrospinal fluid (CSF) leaks in endoscopic skull-base surgery. Retrospective chart review. London Health Sciences Centre. A database of endoscopic skull-base cases between 2007 and 2009 that involved CSF leakage repaired with DuraSeal was created. Demographic data and operative reports were collected and analyzed qualitatively. Recurrence of CSF leak after repair. Five cases were identified that met study criteria. In four of the five cases, the repair was successful. There were no complications related to DuraSeal use. Comparison to a subset of patients using Tisseel Fibrin Sealant (Baxter, Toronto, ON) for repair did not show a significant difference in failure rate (χ2 = 0.029, p = .858). There are a variety of techniques described to repair CSF rhinorrhea, with various studies demonstrating the advantages of using tissue glues in CSF leak repairs. We used DuraSeal in five patients to enhance graft strength and form a watertight seal. The system was effective in the majority of patients. Our study is the first to report on endoscopic endonasal repair of CSF leaks using DuraSeal.

The Management of Cerebrospinal Fluid Leak After Anterior Cervical Decompression Surgery.

PubMed

Zhai, Jiliang; Panchal, Ripul R; Tian, Ye; Wang, Shujie; Zhao, Lijuan

2018-03-01

Cerebrospinal fluid (CSF) leak is a rare but potentially troublesome and occasionally catastrophic complication after anterior cervical decompression surgery. There is limited literature describing this complication, and the management of CSF leak varies. The aim of this study was to retrospectively review the treatment of cases with CSF leak and develop a management algorithm. A series of 14 patients with CSF leak from January 2011 to May 2016 were included in this study. Their characteristics, management of CSF leak, and outcomes were documented. There were 5 male and 9 female patients. Mean age at surgery was 57.1±9.9 years (range, 37-76 years). All instances of CSF leak, except 1 noted postoperatively, were indirectly repaired intraoperatively. A closed straight wound drain was placed for all patients. A lumbar subarachnoid drain was placed immediately after surgery in 4 patients and postoperatively in 7 patients. In 1 patient, lumbar drain placement was unsuccessful. In 2 additional patients, the surgeon decided not to place a lumbar drain. One patient developed meningitis and recovered after antibiotic therapy with meropenem and vancomycin. Another patient had a deep wound infection and required a revision surgery. Wound drains and lumbar drains should be immediately considered when CSF leak is identified. Antibiotics also should be considered to prevent intradural infection. [Orthopedics. 2018; 41(2):e283-e288.]. Copyright 2018, SLACK Incorporated.

The effect of autologous fibrin tissue adhesive on postoperative cerebrospinal fluid leak in spinal cord surgery: a randomized controlled trial.

PubMed

Nakamura, Hiroshi; Matsuyama, Yukihiro; Yoshihara, Hisatake; Sakai, Yoshihito; Katayama, Yoshito; Nakashima, Shojiro; Takamatsu, Jyunki; Ishiguro, Naoki

2005-07-01

A prospective randomized study evaluating the efficacy of autologous fibrin tissue adhesive for decreasing postoperative cerebrospinal fluid (CSF) leak in spinal cord surgery. To compare postoperative CSF leak in 3 groups (i.e., autologous fibrin tissue adhesive used, commercial fibrin glue used, and no fibrin tissue adhesive used) of patients undergoing spinal surgery who needed dural incision. Spinal cord operations, particularly when dural incision is inevitable, sometimes involve postoperative CSF leak. Because CSF leak is a serious complication, countermeasure is necessary to prevent it after dural suture. Commercial fibrin tissue adhesive was formerly used. Because the possibility of prion infection was widely noticed, commercial fibrin tissue adhesive containing animal components has been used less often. In 13 of 39 cases in which dural incision would be made, 400 mL whole blood was drawn, and autologous fibrin tissue adhesive was made of plasma. Cases were divided into 3 groups: (1) dural closure alone, (2) use of autologous fibrin tissue adhesive after dural closure, and (3) use of commercial fibrin tissue adhesive after dural closure. The primary outcome measure was determined as postoperative (3 days) volume of drainage fluid, and results were analyzed using the analysis of variance. The secondary outcome measure was general blood test, coagulation assay, and plasma fibrinogen, and these were analyzed also using the analysis of variance. There was a significant difference in the primary outcome between the autologous and control groups. No complications such as infection or continuous CSF leak were observed in any case. The mean volume of drainage fluid was 586.2 mL in the group with autologous fibrin tissue adhesive and 1026.1 mL in the group without fibrin tissue adhesive. The volume of drainage fluid was significantly lower in the former group than that in the latter group. There was no statistical difference between the volumes of the group with

Connective tissue spectrum abnormalities associated with spontaneous cerebrospinal fluid leaks: a prospective study.

PubMed

Reinstein, Eyal; Pariani, Mitchel; Bannykh, Serguei; Rimoin, David L; Schievink, Wouter I

2013-04-01

We aimed to assess the frequency of connective tissue abnormalities among patients with cerebrospinal fluid (CSF) leaks in a prospective study using a large cohort of patients. We enrolled a consecutive group of 50 patients, referred for consultation because of CSF leak. All patients have been carefully examined for the presence of connective tissue abnormalities, and based on findings, patients underwent genetic testing. Ancillary diagnostic studies included echocardiography, eye exam, and histopathological examinations of skin and dura biopsies in selected patients. We identified nine patients with heritable connective tissue disorders, including Marfan syndrome, Ehlers-Danlos syndrome and other unclassified forms. In seven patients, spontaneous CSF leak was the first noted manifestation of the genetic disorder. We conclude that spontaneous CSF leaks are associated with a spectrum of connective tissue abnormalities and may be the first noted clinical presentation of the genetic disorder. We propose that there is a clinical basis for considering spontaneous CSF leak as a clinical manifestation of heritable connective tissue disorders, and we suggest that patients with CSF leaks should be screened for connective tissue and vascular abnormalities.

Simulation and evaluation of respirator faceseal leaks using computational fluid dynamics and infrared imaging.

PubMed

Lei, Zhipeng; Yang, James; Zhuang, Ziqing; Roberge, Raymond

2013-05-01

This paper presents a computational fluid dynamics (CFD) simulation approach for the prediction of leakage between an N95 filtering facepiece respirator (FFR) and a headform and an infrared camera (IRC) method for validating the CFD approach. The CFD method was used to calculate leak location(s) and 'filter-to-faceseal leakage' (FTFL) ratio for 10 headforms and 6 FFRs.The computational geometry and leak gaps were determined from analysis of the contact simulation results between each headform-N95 FFR combination. The volumetric mesh was formed using a mesh generation method developed by the authors. The breathing cycle was described as a time-dependent profile of the air velocity through the nostril. Breathing air passes through both the FFR filter medium and the leak gaps. These leak gaps are the areas failing to achieve a seal around the circumference of the FFR. The CFD approach was validated by comparing facial temperatures and leak sites from IRC measurements with eight human subjects. Most leaks appear at the regions of the nose (40%) and right (26%) and left cheek (26%) sites. The results also showed that, with N95 FFR (no exhalation valves) use, there was an increase in the skin temperature at the region near the lip, which may be related to thermal discomfort. The breathing velocity and the viscous resistance coefficient of the FFR filter medium directly impacted the FTFL ratio, while the freestream flow did not show any impact on the FTFL ratio. The proposed CFD approach is a promising alternative method to study FFR leakage if limitations can be overcome.

[External lumbar drainage with volumetric continuing infusion pump in patients with cerebrospinal fluid leak. A case series].

PubMed

Manso Melgosa, Ana Belén; García Gutiérrez, Helena; Fernández Porras, Mónica; Castrillo Manero, Ana Berta; Pérez Marijuán, Belén

To describe the incidence and complications arising in a number of cases of patients with cerebrospinal fluid leak treated by external lumbar drainage with infusion pump (IP) volumetric continuous from 2001 to 2014. Quantify cerebrospinal fluid leak closed by lumbar drainage with IP. Retrospective descriptive case series study. patients undergoing transsphenoidal pituitary surgery, Chiari surgery and laminectomy, that developed postoperative cerebrospinal fluid leak treated with continuous external lumbar drainage by IP. age, sex, type of intervention, variables related to the practice of the pump and complications. Average and medians were calculated for quantitative variables, frequencies and percentages for qualitative. Sample: 11 subjects. Incidence in running IP: disconnection, occlusion and acoustic alarm activation. Most frequently complication is headache; a case of pneumocephalus. The small number of subjects and the heterogeneity of these do not allow for comparison or establishing associations between variables. The resolution of the cerebrospinal fluid leak with continuous IP is lower in this study than others, and may be influenced by the small number of subjects. It should be noted the frequent activation of the pump alarm for no apparent cause. Protocol would be developed for preparing the IP team to reduce the acoustic alarm activation, and would make a prospective multicenter study. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

Endoscopic transpterygoidal repair of a large cranial defect with cerebrospinal fluid leak in a patient with extensive osteoradionecrosis of the skull base: case report and technical note.

PubMed

Brand, Y; Lim, E; Waran, V; Prepageran, N

2015-12-01

Endoscopic endonasal techniques have recently become the method of choice in dealing with cerebrospinal fluid leak involving the anterior cranial fossa. However, most surgeons prefer an intracranial approach when leaks involve the middle cranial fossa. This case report illustrates the possibilities of using endoscopic techniques for cerebrospinal fluid leaks involving the middle fossa. A 37-year-old male patient presented with multiple areas of cranial defect with cerebrospinal fluid leak due to osteoradionecrosis following radiation for nasopharyngeal carcinoma 4 years earlier. Clinical examination showed involvement of all cranial nerves except the IInd and XIth nerves on the left side. A prior attempt to repair the cerebrospinal fluid leak with craniotomy was not successful. This case demonstrates the successful endoscopic repair of a large cranial defect with cerebrospinal fluid leak.

Can the Risks of Cerebrospinal Fluid Leak After Vestibular Schwannoma Surgery Be Predicted?

PubMed

Russel, Adrien; Hoffmann, Charles P; Nguyen, Duc T; Beurton, Renaud; Parietti-Winkler, Cécile

2017-02-01

Identifying predictive factors of cerebrospinal fluid (CSF) leak after translabyrinthine approach (TLA) for vestibular schwannoma. Retrospective study. Tertiary care center. All patients (n = 275) operated for a vestibular schwannoma by TLA between 2004 and 2013 were included. Vestibular schwannoma surgery by TLA. The rate of postoperative CSF leak considering the age, sex, body mass index (BMI), tumor staging, and duration of surgical procedure. A logistic regression model was used to identify the predictors and compute a biometric predictive model of CSF leak. Thirty-three patients (12.0%) developed a CSF leak after surgery. In a multivariable model, an increased risk of CSF leak was found for younger patients (OR 0.95, 95% CI 0.92-0.98), longer duration of surgery (OR 1.85, 95% CI 1.12-3.05), and the male sex (0 = male; 1 = female; OR 0.22, 95% CI 0.09-0.54), while also adjusting for BMI. The probability of developing a CSF leak after vestibular schwannoma surgery was calculated using a statistical prediction model, with a percentage of false negative of 7.0% and an overall correct prediction of 88.4%. The predictors of CSF leak after TLA for vestibular schwannoma are young age, male sex, longer duration of surgery, which adjusting for BMI. In this regard, the surgical team should adapt its management during pre- and postoperative period to decrease the likelihood of a leak.

Lumbar subarachnoid drainage in cerebrospinal fluid leaks after lateral skull base surgery.

PubMed

Allen, Kyle P; Isaacson, Brandon; Purcell, Patricia; Kutz, Joe Walter; Roland, Peter S

2011-12-01

To determine the efficacy of lumbar drainage in managing cerebrospinal fluid (CSF) leak after lateral skull base surgery. Retrospective case review. Academic tertiary referral center. Patients who had a lumbar subarachnoid drain placed after a lateral skull base procedure between July 1999 and February 2010 were included. Patients were identified by searching medical records for lateral skull base approach Current Procedural Terminology codes. The following variables were recorded for each subject: diagnosis, type of lateral skull base operation, duration of lumbar drainage, need for revision surgery, and presence of meningitis. Successful cessation of postoperative CSF leakage. Five hundred eight charts were reviewed, and 63 patients were identified who received a lumbar drain after a lateral skull base operation. The most common diagnosis was acoustic neuroma in 61.9%. The most common skull base approaches were the translabyrinthine, middle fossa, and transpetrosal approaches. Approximately 60.3% of patients had CSF rhinorrhea, 23.8% had an incisional leak, and 14.3% had otorrhea. The mean duration of lumbar drainage was 4.6 days. Forty eight (76.2%) study subjects had resolution of their CSF leak with lumbar drainage. Fifteen patients (23.8%) required revision surgery to stop the CSF leak. Lumbar drainage was successful in 90% of leaks after the translabyrinthine approach but in only 50% of those undergoing a suboccipital approach, which was a statistically significant difference. Postoperative CSF leaks after lateral skull base surgery can be managed with a lumbar subarachnoid drain in a majority of cases but is more successful after the translabyrinthine than the suboccipital approach. Recurrent CSF leaks after lumbar drainage is likely to require a revision operation.

[Endonasal endoscopic surgery in the treatment of spontaneous or post-traumatic cerebrospinal fluid (csf) leaks].

PubMed

Nallet, E; Decq, P; Bezzo, A; Le Lievre, G; Peynegre, R; Coste, A

1998-10-01

The incidence and the risk of meningitidis justify treatment in all cases of cerebrospinal fluid rhinorrhea with spontaneous etiology or after traumatic injury. Endonasal surgery with endoscopic instruments provides many advantages compared with transcranial or transfacial approach used by neurosurgeons. We report our experience and our surgical technique in the treatment of CSF leaks in 5 patients. Intrathecal injection of fluoresceine was very useful in all cases for detecting the CSF leak. Total or selected ethmoidectomy depended on the localization of the leakage. Wide sphenoidotomy enables detection and repair of CSF leaks from the sphenoid cavity. A free graft of inferior turbinal mucosal was used to repair the breache. This rapid low morbidity surgery offered secure closure of rhinorrhea in 4 cases after one procedure and in 1 case after two procedures with an average follow up of 22 months. Cerebrospinal fluid rhinorrhea can be managed in first line therapy with endoscopic intranasal surgical techniques when they are localized in the anterior ethmoid or in the sphenoid cavity.

Sinus anatomy associated with inadvertent cerebrospinal fluid leak during functional endoscopic sinus surgery.

PubMed

Heaton, Chase M; Goldberg, Andrew N; Pletcher, Steven D; Glastonbury, Christine M

2012-07-01

Anatomic variations in skull base anatomy may predispose the surgeon to inadvertent skull base injury with resultant cerebrospinal fluid (CSF) leak during functional endoscopic sinus surgery (ESS). Our objective was to compare preoperative sinus imaging of patients who underwent FESS with and without CSF leak to elucidate these variations. In this retrospective case-control study, 18 patients with CSF leak following FESS for chronic rhinosinusitis (CRS) from 2000 to 2011 were compared to 18 randomly selected patients who underwent preoperative imaging for FESS for CRS. Measurements were obtained from preoperative computed tomography images with specific attention to anatomic differences in cribriform plate and ethmoid roof heights in the coronal plane, and the skull base angle in the sagittal plane. Mean values of measured variables were compared using a nonparametric Mann-Whitney test. When compared to controls, patients with CSF leak demonstrated a greater angle of the skull base in the sagittal plane (P < .001) and a greater slope of the skull base in the coronal plane (P < .006). A lower cribriform height relative to ethmoid roof height was also noted in cases of CSF leak as compared to controls (P < .04). A steep skull base angle in the sagittal plane, a greater slope of the skull base in the coronal plane, and a low cribriform height relative to the ethmoid roof predispose the patient to CSF leak during FESS. Preoperative review of imaging with specific attention paid to these anatomic variations may help to prevent iatrogenic CSF leak. Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.

Risk factors for cerebrospinal fluid leak in pediatric patients undergoing endoscopic endonasal skull base surgery.

PubMed

Stapleton, Amanda L; Tyler-Kabara, Elizabeth C; Gardner, Paul A; Snyderman, Carl H; Wang, Eric W

2017-02-01

To determine the risk factors associated with cerebrospinal fluid (CSF) leak following endoscopic endonasal surgery (EES) for pediatric skull base lesions. Retrospective chart review of pediatric patients (ages 1 month to 18 years) treated for skull base lesions with EES from 1999 to 2014. Five pathologies were reviewed: craniopharyngioma, clival chordoma, pituitary adenoma, pituitary carcinoma, and Rathke's cleft cyst. Fisher's exact tests were used to evaluate the different factors to determine which had a statistically higher risk of leading to a post-operative CSF leak. 55 pediatric patients were identified who underwent 70 EES's for tumor resection. Of the 70 surgeries, 47 surgeries had intraoperative CSF leaks that were repaired at the time of surgery. 11 of 47 (23%) surgeries had post-operative CSF leaks that required secondary operative repair. Clival chordomas had the highest CSF leak rate at 36%. There was no statistical difference in leak rate based on the type of reconstruction, although 28% of cases that used a vascularized flap had a post-operative leak, whereas only 9% of those cases not using a vascularized flap had a leak. Post-operative hydrocephalus and perioperative use of a lumbar drain were not significant risk factors. Pediatric patients with an intra-operative CSF leak during EES of the skull base have a high rate of post-operative CSF leaks. Clival chordomas appear to be a particularly high-risk group. The use of vascularized flaps and perioperative lumbar drains did not statistically decrease the rate of post-operative CSF leak. Copyright © 2017 Elsevier B.V. All rights reserved.

Stochastic Consequence Analysis for Waste Leaks

DOE Office of Scientific and Technical Information (OSTI.GOV)

HEY, B.E.

This analysis evaluates the radiological consequences of potential Hanford Tank Farm waste transfer leaks. These include ex-tank leaks into structures, underneath the soil, and exposed to the atmosphere. It also includes potential misroutes, tank overflow

The role of ICP monitoring in patients with persistent cerebrospinal fluid leak following spinal surgery: a case series.

PubMed

Craven, Claudia; Toma, Ahmed K; Khan, Akbar A; Watkins, Laurence D

2016-09-01

Cerebrospinal fluid (CSF) leak following spinal surgery is a relatively common surgical complication. A disturbance in the underlying CSF dynamics could be the causative factor in a small group of patients with refractory CSF leaks that require multiple surgical repairs and prolonged hospital admission. A retrospective case series of patients with persistent post spinal surgery CSF leak referred to the hydrocephalus service for continuous intracranial pressure (ICP) monitoring. Patients' notes were reviewed for medical history, ICP data, radiological data, and subsequent management and outcome. Five patients (two males/three females, mean age, 35.4 years) were referred for ICP monitoring over a 12-month period. These patients had prolonged CSF leak despite multiple repair attempts 252 ± 454 days (mean ± SD). On ICP monitoring, all five patients had abnormal results, with the mean ICP 8.95 ± 4.41 mmHg. Four had abnormal pulse amplitudes, mean 6.15 mmHg ± 1.22 mmHg. All five patients underwent an intervention. Three patients underwent insertion of ventriculoperitoneal (VP) shunts. One patient had venous sinus stent insertion and one patient underwent medical management with acetazolamide. All five of the patients' CSF leak resolved post intervention. The mean time to resolution of CSF leak post intervention was 10.8  ± 12.9 days. Abnormal cerebrospinal fluid dynamics could be the underlying factor in patients with a persistent and treatment-refractory CSF leak post spinal surgery. Treatments aimed at lowering ICP may be beneficial in this group of patients. Whether abnormal pressure and dynamics represent a pre-existing abnormality or is induced by spinal surgery should be a subject of further study.

Leak and Pipe Detection Method and System

NASA Technical Reports Server (NTRS)

Youngquist, Robert C. (Inventor)

2003-01-01

A method and system for locating leaks of conductive fluids from non-conductive pipes and other structures or for locat- ing non-conductive pipes or structures having conductive fluid contained therein, employ a charge generator to apply a time varying charge to the conductive fluid, and a capaci- tive type detector that can detect the variable charge that is induced in the fluid. The capacitive detector, which prefer- ably includes a handheld housing, employs a large conduc- tive pickup plate that is used to locate the pipe or leak by scanning the plate over the ground and detecting the induced charge that is generated when the plate comes in close proximity to the pipe or leak. If a leak is encountered, the resulting signal will appear over an area larger than expected for a buried pipe, assuming the leak provides an electrically conductive path between the flow and the wet surrounding ground. The detector uses any suitable type of indicator device, such as a pair of headphones that enable an operator to hear the detected signal as a chirping sound, for example.

Assessments of fluid friction factors for use in leak rate calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chivers, T.C.

1997-04-01

Leak before Break procedures require estimates of leakage, and these in turn need fluid friction to be assessed. In this paper available data on flow rates through idealized and real crack geometries are reviewed in terms of a single friction factor k It is shown that for {lambda} < 1 flow rates can be bounded using correlations in terms of surface R{sub a} values. For {lambda} > 1 the database is less precise, but {lambda} {approx} 4 is an upper bound, hence in this region flow calculations can be assessed using 1 < {lambda} < 4.

Comprehensive Quantitative Analysis on Privacy Leak Behavior

PubMed Central

Fan, Lejun; Wang, Yuanzhuo; Jin, Xiaolong; Li, Jingyuan; Cheng, Xueqi; Jin, Shuyuan

2013-01-01

Privacy information is prone to be leaked by illegal software providers with various motivations. Privacy leak behavior has thus become an important research issue of cyber security. However, existing approaches can only qualitatively analyze privacy leak behavior of software applications. No quantitative approach, to the best of our knowledge, has been developed in the open literature. To fill this gap, in this paper we propose for the first time four quantitative metrics, namely, possibility, severity, crypticity, and manipulability, for privacy leak behavior analysis based on Privacy Petri Net (PPN). In order to compare the privacy leak behavior among different software, we further propose a comprehensive metric, namely, overall leak degree, based on these four metrics. Finally, we validate the effectiveness of the proposed approach using real-world software applications. The experimental results demonstrate that our approach can quantitatively analyze the privacy leak behaviors of various software types and reveal their characteristics from different aspects. PMID:24066046

Comprehensive quantitative analysis on privacy leak behavior.

PubMed

Fan, Lejun; Wang, Yuanzhuo; Jin, Xiaolong; Li, Jingyuan; Cheng, Xueqi; Jin, Shuyuan

2013-01-01

Privacy information is prone to be leaked by illegal software providers with various motivations. Privacy leak behavior has thus become an important research issue of cyber security. However, existing approaches can only qualitatively analyze privacy leak behavior of software applications. No quantitative approach, to the best of our knowledge, has been developed in the open literature. To fill this gap, in this paper we propose for the first time four quantitative metrics, namely, possibility, severity, crypticity, and manipulability, for privacy leak behavior analysis based on Privacy Petri Net (PPN). In order to compare the privacy leak behavior among different software, we further propose a comprehensive metric, namely, overall leak degree, based on these four metrics. Finally, we validate the effectiveness of the proposed approach using real-world software applications. The experimental results demonstrate that our approach can quantitatively analyze the privacy leak behaviors of various software types and reveal their characteristics from different aspects.

Heat exchanger with leak detecting double wall tubes

DOEpatents

Bieberbach, George; Bongaards, Donald J.; Lohmeier, Alfred; Duke, James M.

1981-01-01

A straight shell and tube heat exchanger utilizing double wall tubes and three tubesheets to ensure separation of the primary and secondary fluid and reliable leak detection of a leak in either the primary or the secondary fluids to further ensure that there is no mixing of the two fluids.

Intraoperative seizure and cerebrospinal fluid leak during adult cochlear implant surgery.

PubMed

Musser, Alexander B; Golub, Justin S; Samy, Ravi N; Phero, James C

2016-01-01

To report a rare case of cerebrospinal fluid gusher and subsequent seizure immediately after cochlear implant electrode insertion. After the cochlear implant electrode was inserted, brisk flow of 10 mL of cerebrospinal fluid was seen. The electrode was promptly inserted and the leak was additionally sealed with fascia. Seconds later, the patient had a tonic-clonic seizure lasting 30 seconds. Two additional episodes occurred during the case. Her postoperative course was uneventful with no subsequent seizures. The device has been successfully activated. Intervention & Technique: Postoperative imaging showed correct intracochlear placement of the electrode as well as an incidental enlarged vestibular aqueduct. Neurology consultation including electroencephalogram was unremarkable. To our knowledge, this is the first report of a seizure temporally associated with cochlear implant electrode insertion. The significance and possible casual relationship between these two events is discussed.

Leak detection aid

DOEpatents

Steeper, Timothy J.

1989-01-01

A leak detection apparatus and method for detecting leaks across an O-ring sealing a flanged surface to a mating surface is an improvement in a flanged surface comprising a shallow groove following O-ring in communication with an entrance and exit port intersecting the shallow groove for injecting and withdrawing, respectively, a leak detection fluid, such as helium. A small quantity of helium injected into the entrance port will flow to the shallow groove, past the O-ring and to the exit port.

Leak detection aid

DOEpatents

Steeper, T.J.

1989-12-26

A leak detection apparatus and method for detecting leaks across an O-ring sealing a flanged surface to a mating surface is an improvement in a flanged surface comprising a shallow groove following O-ring in communication with an entrance and exit port intersecting the shallow groove for injecting and withdrawing, respectively, a leak detection fluid, such as helium. A small quantity of helium injected into the entrance port will flow to the shallow groove, past the O-ring and to the exit port. 2 figs.

Detecting well casing leaks in Bangladesh using a salt spiking method

USGS Publications Warehouse

Stahl, M.O.; Ong, J.B.; Harvey, C.F.; Johnson, C.D.; Badruzzaman, A.B.M.; Tarek, M.H.; VanGeen, A.; Anderson, J.A.; Lane, J.W.

2014-01-01

We apply fluid-replacement logging in arsenic-contaminated regions of Bangladesh using a low-cost, down-well fluid conductivity logging tool to detect leaks in the cased section of wells. The fluid-conductivity tool is designed for the developing world: it is lightweight and easily transportable, operable by one person, and can be built for minimal cost. The fluid-replacement test identifies leaking casing by comparison of fluid conductivity logs collected before and after spiking the wellbore with a sodium chloride tracer. Here, we present results of fluid-replacement logging tests from both leaking and non-leaking casing from wells in Araihazar and Munshiganj, Bangladesh, and demonstrate that the low-cost tool produces measurements comparable to those obtained with a standard geophysical logging tool. Finally, we suggest well testing procedures and approaches for preventing casing leaks in Bangladesh and other developing countries.

[Management of cerebrospinal fluid leaks according to size. Our experience].

PubMed

Alobid, Isam; Enseñat, Joaquim; Rioja, Elena; Enriquez, Karla; Viscovich, Liza; de Notaris, Matteo; Bernal-Sprekelsen, Manuel

2014-01-01

We present our experience in the reconstruction of cerebrospinal fluid (CSF) leaks according to their size and location. Fifty-four patients who underwent advanced skull base surgery (large defects) and 62 patients with CSF leaks of different origin (small and medium-sized defects) were included. Large defects were reconstructed with a nasoseptal pedicled flap positioned on fat and fascia lata and lumbar drainage was used. In small and medium-sized leaks of other origin, intrathecal fluorescein 5% was applied previously to identify the defect. Fascia lata in an underlay position was used for reconstruction, which was then covered with mucoperiosteum from the turbinate. Perioperative antibiotics were administered for 5-7 days. Nasal packing was removed after 24-48 hours. The most frequent aetiology for small and medium-sized defects was spontaneous (48.4%), followed by trauma (24.2%), iatrogenic (5%) and others. The success rate was of 91% after the first surgery and 98% in large skull base defects and small/medium-sized respectively. After rescue surgery, the rate of closure achieved was 100%. The follow-up was 15.6 ± 12.4 months for large defects and 75.3 ± 51.3 months for small/medium-sized defects without recurrence. Endoscopic surgery for closure of any type of skull base defect is the gold standard approach. Defect size does not play a significant role in the success rate. Fascia lata and mucoperiosteum allow a reconstruction of small/medium-sized defects. For larger skull base defects, a combination of fat, fascia lata and nasoseptal pedicled flaps provide a successful reconstruction. Copyright © 2013 Elsevier España, S.L. All rights reserved.

Fluid management in critically ill patients: the role of extravascular lung water, abdominal hypertension, capillary leak, and fluid balance

PubMed Central

2012-01-01

Introduction Capillary leak in critically ill patients leads to interstitial edema. Fluid overload is independently associated with poor prognosis. Bedside measurement of intra-abdominal pressure (IAP), extravascular lung water index (EVLWI), fluid balance, and capillary leak index (CLI) may provide a valuable prognostic tool in mechanically ventilated patients. Methods We performed an observational study of 123 mechanically ventilated patients with extended hemodynamic monitoring, analyzing process-of-care variables for the first week of ICU admission. The primary outcome parameter was 28-day mortality. ΔmaxEVLWI indicated the maximum difference between EVLWI measurements during ICU stay. Patients with a ΔmaxEVLWI <−2 mL/kg were called 'responders'. CLI was defined as C-reactive protein (milligrams per deciliter) over albumin (grams per liter) ratio and conservative late fluid management (CLFM) as even-to-negative fluid balance on at least two consecutive days. Results CLI had a biphasic course. ΔmaxEVLWI was lower if CLFM was achieved and in survivors (−2.4 ± 4.8 vs 1.0 ± 5.5 mL/kg, p = 0.001; −3.3 ± 3.8 vs 2.5 ± 5.3 mL/kg, p = 0.001, respectively). No CLFM achievement was associated with increased CLI and IAPmean on day 3 and higher risk to be nonresponder (odds ratio (OR) 2.76, p = 0.046; OR 1.28, p = 0.011; OR 5.52, p = 0.001, respectively). Responders had more ventilator-free days during the first week (2.5 ± 2.3 vs 1.5 ± 2.3, p = 0.023). Not achieving CLFM and being nonresponder were strong independent predictors of mortality (OR 9.34, p = 0.001 and OR 7.14, p = 0.001, respectively). Conclusion There seems to be an important correlation between CLI, EVLWI kinetics, IAP, and fluid balance in mechanically ventilated patients, associated with organ dysfunction and poor prognosis. In this context, we introduce the global increased permeability syndrome. PMID:22873410

Detecting well casing leaks in Bangladesh using a salt spiking method.

PubMed

Stahl, M O; Ong, J B; Harvey, C F; Johnson, C D; Badruzzaman, A B M; Tarek, M H; van Geen, A; Anderson, J A; Lane, J W

2014-09-01

We apply fluid-replacement logging in arsenic-contaminated regions of Bangladesh using a low-cost, down-well fluid conductivity logging tool to detect leaks in the cased section of wells. The fluid-conductivity tool is designed for the developing world: it is lightweight and easily transportable, operable by one person, and can be built for minimal cost. The fluid-replacement test identifies leaking casing by comparison of fluid conductivity logs collected before and after spiking the wellbore with a sodium chloride tracer. Here, we present results of fluid-replacement logging tests from both leaking and non-leaking casing from wells in Araihazar and Munshiganj, Bangladesh, and demonstrate that the low-cost tool produces measurements comparable to those obtained with a standard geophysical logging tool. Finally, we suggest well testing procedures and approaches for preventing casing leaks in Bangladesh and other developing countries. © 2014, National Ground Water Association.

Spontaneous cerebrospinal fluid leak from an anomalous thoracic nerve root: case report.

PubMed

Lopez, Alejandro J; Campbell, Robert K; Arnaout, Omar; Curran, Yvonne M; Shaibani, Ali; Dahdaleh, Nader S

2016-12-01

The authors report the case of a 28-year-old woman with a spontaneous cerebrospinal fluid leak from the sleeve of a redundant thoracic nerve root. She presented with postural headaches and orthostatic symptoms indicative of intracranial hypotension. CT myelography revealed that the lesion was located at the T-11 nerve root. After failure of conservative management, including blood patches and thrombin glue injections, the patient was successfully treated with surgical decompression and ligation of the duplicate nerve, resulting in full resolution of her orthostatic symptoms.

Postoperative ascitic leaks: the ongoing challenge.

PubMed

Rosemurgy, A S; Statman, R C; Murphy, C G; Albrink, M H; McAllister, E W

1992-06-01

The leak of ascitic fluid from surgical incisions is thought to be associated with a very high mortality rate. There have been few reports, however, focusing on the clinical characteristics, management, or mortality rates of this condition. During a 10-year period, 18 patients with postoperative ascitic fluid leaks were treated. All patients had ascites before surgery and all had liver disease; in 13 of the 18 patients alcoholic liver disease was the cause of ascites. Ten of the 18 patients died (56%). Midline incisions were more often associated with recalcitrant leaks and fatal complications than were transverse incisions. Early consideration of fascial dehiscence and prompt repair is emphasized. The most effective predictor of survival was cessation of the leak.

Comprehensive leak detection survey and benefit/cost analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scholze, R.J. Jr.; Maloney, S.W.

1995-06-01

Fort Carson, Colorado was the site of a comprehensive leak detection investigation of the potable water system with the express purpose of quantifying the benefits to be derived by a military installation from use of leak detection and repair technology. Military bases are often the size of a small city and one Directorate or Department has responsibility for all real estate (buildings, roads, grounds, etc.) unlike a municipal public works department. The investigation used state of the art noise correlation and computer correlation technology to survey the distribution system mains. This was complemented by a building to building survey coveringmore » office and commercial buildings along with family and barracks housing where investigators entered buildings and quantified visible leaks in faucets and water closets, etc. Following repairs and a year`s time, a follow-on survey is performed to again examine all aspects of the system. The result was a complete economic evaluation and benefit/cost analysis of the installation. Representative findings include: the majority of distribution system leaks were at hydrants or similar appurtenances; and family housing was found to be the other major concentration of leaks. However, where the first survey found 80 percent of housing units had leaks, findings from the second round on the order of 20 percent. Office buildings were found from the first survey to not merit follow-on attention due to limited numbers of leaks. Water-consciousness was raised for both the responsible directorate and individuals in family housing and leak repair was given a higher priority for repairs. This paper will outline the leak detection methodology used, characterize the types and patterns of leaks found, introduce an economic analysis for the entire leak detection process, and finally, provide lessons learned with practical results and implications.« less

Spinal cerebrospinal fluid leak as the cause of chronic subdural hematomas in nongeriatric patients.

PubMed

Beck, Jürgen; Gralla, Jan; Fung, Christian; Ulrich, Christian T; Schucht, Philippe; Fichtner, Jens; Andereggen, Lukas; Gosau, Martin; Hattingen, Elke; Gutbrod, Klemens; Z'Graggen, Werner J; Reinert, Michael; Hüsler, Jürg; Ozdoba, Christoph; Raabe, Andreas

2014-12-01

The etiology of chronic subdural hematoma (CSDH) in nongeriatric patients (≤ 60 years old) often remains unclear. The primary objective of this study was to identify spinal CSF leaks in young patients, after formulating the hypothesis that spinal CSF leaks are causally related to CSDH. All consecutive patients 60 years of age or younger who underwent operations for CSDH between September 2009 and April 2011 at Bern University Hospital were included in this prospective cohort study. The patient workup included an extended search for a spinal CSF leak using a systematic algorithm: MRI of the spinal axis with or without intrathecal contrast application, myelography/fluoroscopy, and postmyelography CT. Spinal pathologies were classified according to direct proof of CSF outflow from the intrathecal to the extrathecal space, presence of extrathecal fluid accumulation, presence of spinal meningeal cysts, or no pathological findings. The primary outcome was proof of a CSF leak. Twenty-seven patients, with a mean age of 49.6 ± 9.2 years, underwent operations for CSDH. Hematomas were unilateral in 20 patients and bilateral in 7 patients. In 7 (25.9%) of 27 patients, spinal CSF leakage was proven, in 9 patients (33.3%) spinal meningeal cysts in the cervicothoracic region were found, and 3 patients (11.1%) had spinal cysts in the sacral region. The remaining 8 patients (29.6%) showed no pathological findings. The direct proof of spinal CSF leakage in 25.9% of patients suggests that spinal CSF leaks may be a frequent cause of nongeriatric CSDH.

Smokestack leak in central serous chorioretinopathy.

PubMed

Bujarborua, Dhiren; Nagpal, Pran N; Deka, Manab

2010-03-01

To study the demography, various morphological patterns and fluid dynamics of the smokestack leak by fluorescein angiography (FA) in central serous chorioretinopathy (CSC). Part I (clinical): review of the medical records and angiographic documents of 69 consecutive cases of CSC with smokestack leak. Part II (experimental): documentation of the movement of various concentrations of fluorescein dye due to convection currents in a laboratory model that roughly represents a closed chamber similar to that of CSC in human eyes. The clinical study (Part I) revealed that 14.40% of 479 consecutive cases had smokestack leak, of which 70% occurred in first acute episode (p-value: <0.001), 27.14% in acute recurrent episodes (50% fresh leak) and 2.85% in chronic stage. Patients were predominantly male (84.05%) with a median age of 34.00 +/- 8.14 years. The median symptom duration excluding the chronic cases was 15 +/- 34.28 days. This type of leak was mostly (48.57%) seen in medium-sized CSC, and the majority were in the parafoveal superonasal quadrant (31.42%). The ascending type of leak was predominant (94.28%). In four eyes, an atypical pattern and in two eyes more than one smokestack leak were seen within the same detached area. The experimental study (Part II) demonstrated that fluid containing a low concentration of fluorescein ascended due to convection currents, whereas highly concentrated dye descended. The clinical study revealed smokestack leaks to be significantly more common in a primary acute episode, and they usually develop in the early part of the acute phase of the disease (average duration 15 +/- 34.28 days). Rarely, this type of leak can occur in the chronic stage, and multiple leaks may develop in the same detached space. The various patterns of dye movement due to convection currents in the experimental model resembled the dye movement in certain cases of CSC of the present series. The experimental study also hinted at the probability of drainage of

Fluid pipeline leak detection and location with miniature RF tags

DOEpatents

McIntyre, Timothy J.

2017-05-16

Sensors locate troublesome leaks in pipes or conduits that carry a flowing medium. These sensors, through tailored physical and geometric properties, preferentially seek conduit leaks or breaches due to flow streaming. The sensors can be queried via transceivers outside the conduit or located and interrogated inside by submersible unmanned vehicle to identify and characterize the nature of a leak. The sensors can be functionalized with other capabilities for additional leak and pipeline characterization if needed. Sensors can be recovered from a conduit flow stream and reused for future leak detection activities.

Low Level Leaks

NASA Technical Reports Server (NTRS)

1998-01-01

NASA has transferred the improved portable leak detector technology to UE Systems, Inc.. This instrument was developed to detect leaks in fluid systems of critical launch and ground support equipment. This system incorporates innovative electronic circuitry, improved transducers, collecting horns, and contact sensors that provide a much higher degree of reliability, sensitivity and versatility over previously used systems. Potential commercial uses are pipelines, underground utilities, air-conditioning systems, petrochemical systems, aerospace, power transmission lines and medical devices.

Coconut Model for Learning First Steps of Craniotomy Techniques and Cerebrospinal Fluid Leak Avoidance.

PubMed

Drummond-Braga, Bernardo; Peleja, Sebastião Berquó; Macedo, Guaracy; Drummond, Carlos Roberto S A; Costa, Pollyana H V; Garcia-Zapata, Marco T; Oliveira, Marcelo Magaldi

2016-12-01

Neurosurgery simulation has gained attention recently due to changes in the medical system. First-year neurosurgical residents in low-income countries usually perform their first craniotomy on a real subject. Development of high-fidelity, cheap, and largely available simulators is a challenge in residency training. An original model for the first steps of craniotomy with cerebrospinal fluid leak avoidance practice using a coconut is described. The coconut is a drupe from Cocos nucifera L. (coconut tree). The green coconut has 4 layers, and some similarity can be seen between these layers and the human skull. The materials used in the simulation are the same as those used in the operating room. The coconut is placed on the head holder support with the face up. The burr holes are made until endocarp is reached. The mesocarp is dissected, and the conductor is passed from one hole to the other with the Gigli saw. The hook handle for the wire saw is positioned, and the mesocarp and endocarp are cut. After sawing the 4 margins, mesocarp is detached from endocarp. Four burr holes are made from endocarp to endosperm. Careful dissection of the endosperm is done, avoiding liquid albumen leak. The Gigli saw is passed through the trephine holes. Hooks are placed, and the endocarp is cut. After cutting the 4 margins, it is dissected from the endosperm and removed. The main goal of the procedure is to remove the endocarp without fluid leakage. The coconut model for learning the first steps of craniotomy and cerebrospinal fluid leak avoidance has some limitations. It is more realistic while trying to remove the endocarp without damage to the endosperm. It is also cheap and can be widely used in low-income countries. However, the coconut does not have anatomic landmarks. The mesocarp makes the model less realistic because it has fibers that make the procedure more difficult and different from a real craniotomy. The model has a potential pedagogic neurosurgical application for

Body mass index and the risk of postoperative cerebrospinal fluid leak following trans-sphenoidal surgery in an Asian population.

PubMed

Sun, Ira; Lim, Jia Xu; Goh, Chun Peng; Low, Shiong Wen; Kirollos, Ramez W; Tan, Chuen Seng; Lwin, Sein; Yeo, Tseng Tsai

2016-09-22

Postoperative cerebrospinal fluid (CSF) leak is a serious complication following trans-sphenoidal surgery for which elevated body mass index (BMI) has been implicated as a risk factor, albeit only in two recent North American studies. Given the paucity of evidence, we sought to determine if this association held true in an Asian population, where BMI criteria for obesity differ from the international standard. A retrospective study of 119 patients who underwent 123 trans-sphenoidal procedures for sellar lesions between May 2000 and May 2012 was conducted. Univariate and multivariate logistic regression analyses were performed to investigate the impact of elevated BMI and other risk factors on postoperative CSF leak. We found 10 (8.1%) procedures in ten patients that were complicated by postoperative CSF leak. The median BMI of patients with postoperative leak following trans-sphenoidal procedures was significantly higher than that of patients without postoperative CSF leak (27.0 kg/m2 vs. 24.6 kg/m2; p = 0.018). Patients categorised as either moderate or high risk under the Asian BMI classification were more likely to suffer from a postoperative leak (p = 0.030). Repeat procedures were also found to be significantly associated with postoperative CSF leak (p = 0.041). Elevated BMI predicts for postoperative CSF leak following trans-sphenoidal procedures, even in an Asian population, where the definition of obesity differs from international standards. Thus, BMI should be borne in mind during local and regional management decision-making processes prior to such procedures.

[Group A streptococcal meningitis: Streptococcus pneumoniae is not the only one to seep into the CSF fluid leak!].

PubMed

Zappella, N; Barrelet, A; Pangon, B; Laurent, V; Bruneel, F

2013-11-01

We reported a case of group A streptococcal meningitis in a patient with a CSF fluid leak. This case underlined several relevant points: (i) an unfrequent cause of bacterial meningitis; (ii) the main diagnosis to evoke when the direct examination of CSF shows Gram+ cocci with a negative pneumococcal antigen; (iii) that bacteria other than Streptococcus pneumoniae are possible in front of a meningitis associated with a CSF fluif leak. Copyright © 2013 Société française d’anesthésie et de réanimation (Sfar). Published by Elsevier SAS. All rights reserved.

Clinical characteristics of 15 cases of chronic subdural hematomas due to spontaneous intracranial hypotension with spinal cerebrospinal fluid leak.

PubMed

Wan, Yingfeng; Xie, Jixi; Xie, Dajiang; Xue, Zhaoliang; Wang, Yirong; Yang, Shuxu

2016-12-01

The etiology of chronic subdural hematoma (CSDH) in patients is diverse. The primary objective of this article was to discuss one of the causes, spontaneous intracranial hypotension with spinal cerebrospinal fluid (CSF) leak, which is usually neglected by the neurosurgeon. All the consecutive 15 patients who underwent operation for CSDHs between June 2012 and June 2014 at Sir Run Run Shaw Hospital of Zhejiang University were included in this retrospective cohort study. The clinical and imaging data of these patients with CSDHs due to spinal CSF leak were retrospectively studied. Fifteen patients, with a mean age of 53.8 ± 8.3 years, underwent operations for CSDH. Hematomas were unilateral in 4 patients and bilateral in 11 patients. Among these patients, eight patients had recurrence of hematomas after operation due to neglect of spinal CSF leak. All patients had fully recovery. Spinal CSF leak is a cause of cSDH, which is overlooked by the doctor.

Capillary leak syndrome: etiologies, pathophysiology, and management.

PubMed

Siddall, Eric; Khatri, Minesh; Radhakrishnan, Jai

2017-07-01

In various human diseases, an increase in capillary permeability to proteins leads to the loss of protein-rich fluid from the intravascular to the interstitial space. Although sepsis is the disease most commonly associated with this phenomenon, many other diseases can lead to a "sepsis-like" syndrome with manifestations of diffuse pitting edema, exudative serous cavity effusions, noncardiogenic pulmonary edema, hypotension, and, in some cases, hypovolemic shock with multiple-organ failure. The term capillary leak syndrome has been used to describe this constellation of disease manifestations associated with an increased capillary permeability to proteins. Diseases other than sepsis that can result in capillary leak syndrome include the idiopathic systemic capillary leak syndrome or Clarkson's disease, engraftment syndrome, differentiation syndrome, the ovarian hyperstimulation syndrome, hemophagocytic lymphohistiocytosis, viral hemorrhagic fevers, autoimmune diseases, snakebite envenomation, and ricin poisoning. Drugs including some interleukins, some monoclonal antibodies, and gemcitabine can also cause capillary leak syndrome. Acute kidney injury is commonly seen in all of these diseases. In addition to hypotension, cytokines are likely to be important in the pathophysiology of acute kidney injury in capillary leak syndrome. Fluid management is a critical part of the treatment of capillary leak syndrome; hypovolemia and hypotension can cause organ injury, whereas capillary leakage of administered fluid can worsen organ edema leading to progressive organ injury. The purpose of this article is to discuss the diseases other than sepsis that produce capillary leak and review their collective pathophysiology and treatment. Copyright © 2017 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

Modified Graded Repair of Cerebrospinal Fluid Leaks in Endoscopic Endonasal Transsphenoidal Surgery

PubMed Central

Park, Jae-Hyun; Choi, Jai Ho; Kim, Young-Il; Kim, Sung Won

2015-01-01

Objective Complete sellar floor reconstruction is critical to avoid postoperative cerebrospinal fluid (CSF) leakage during transsphenoidal surgery. Recently, the pedicled nasoseptal flap has undergone many modifications and eventually proved to be valuable and efficient. However, using these nasoseptal flaps in all patients who undergo transsphenoidal surgery, including those who had none or only minor CSF leakage, appears to be overly invasive and time-consuming. Methods Patients undergoing endoscopic endonasal transsphenoidal tumor surgery within a 5 year-period were reviewed. Since 2009, we classified the intraoperative CSF leakage into grades from 0 to 3. Sellar floor reconstruction was tailored to each leak grade. We did not use any tissue grafts such as abdominal fat and did not include any procedures of CSF diversions such as lumbar drainage. Results Among 200 cases in 188 patients (147 pituitary adenoma and 41 other pathologies), intraoperative CSF leakage was observed in 27.4% of 197 cases : 14.7% Grade 1, 4.6% Grade 2a, 3.0% Grade 2b, and 5.1% Grade 3. Postoperative CSF leakage was observed in none of the cases. Septal bone buttress was used for Grade 1 to 3 leakages instead of any other foreign materials. Pedicled nasoseptal flap was used for Grades 2b and 3 leakages. Unused septal bones and nasoseptal flaps were repositioned. Conclusion Modified classification of intraoperative CSF leaks and tailored repair technique in a multilayered fashion using an en-bloc harvested septal bone and vascularized nasoseptal flaps is an effective and reliable method for the prevention of postoperative CSF leaks. PMID:26279811

Occurrence of occult CSF leaks during standard FESS procedures.

PubMed

Bucher, S; Kugler, A; Probst, E; Epprecht, L; Stadler, R S; Holzmann, D; Soyka, M B

2018-03-18

To determine the incidence of occult cerebrospinal fluid leaks (CSF) after functional endoscopic sinus surgery (FESS) and to evaluate the diagnostic performance of beta2-transferrin in blood-contaminated conditions. Prospective cohort study. An analysis of 57 intraoperative samples using hydrogel 6 beta2-transferrin assay after FESS was undertaken. In case of CSF positive samples and continuing rhinorrhea, reanalysis after more than 1 year was conducted. In-vivo analysis of a primary spontaneous CSF leak sample took place to verify difficulties in detecting beta2-transferrin in blood-contaminated settings. Own titrations were performed to evaluate detection limits of CSF by beta2-transferrin and beta-trace protein assays in these settings. An incidence of 13% for occult CSF leaks after FESS was found. In blood-contaminated conditions, routine beta2-transferrin assays showed low sensitivity. In over 1 year follow-up, all samples were negative for CSF and none of them developed clinical relevant CSF leaks or meningitis. Occult and clinically irrelevant CSF leaks do occur in a significant proportion of patients during and shortly after FESS. Intra- and postoperatively, routine beta2-transferrin assays show low sensitivity. They should not be used in these settings. The clinical course of patients with occult CSF leaks indicated possibility of an uneventful follow-up.

Cerebrospinal fluid leaks following spinal surgery: use of fat grafts for prevention and repair. Technical note.

PubMed

Black, Perry

2002-03-01

Cerebrospinal fluid (CSF) leaks are relatively common following spinal surgery. A midline dural tear in the spine is readily repaired by direct application of sutures; however, far-lateral or ventral dural tears are problematic. Fat is an ideal sealant because it is impermeable to water. In this paper the author reports his experience with using fat grafts for the prevention or repair of CSF leaks and proposes a technique in which a large sheet of fat, harvested from the patient's subcutaneous layer, is used to cover not only the dural tear(s) but all of the exposed dura and is tucked into the lateral recess. This procedure prevents CSF from seeping around the fat, which may be tacked to the dura with a few sutures. Fibrin glue is spread on the surface of the fat and is further covered with Surgicel or Gelfoam. For ventral dural tears (associated with procedures in which disc material is excised), fat is packed into the disc space to seal off the ventral dural leak. Dural suture lines following spinal intradural exploration are prophylatically protected from CSF leakage in the same manner. With one exception, 27 dural tears noted during 1650 spinal procedures were successfully repaired using this technique. There was one case of postoperative CSF leakage in 140 cases in which intradural exploration for tumor or other lesions was undertaken. Both postoperative CSF leaks were controlled by applying additional skin sutures. The use of a fat graft is recommended as a rapid, effective means of prevention and repair of CSF leaks following spinal surgery.

Combined Endoscopic Transorbital and Endonasal Repair of High Flow Orbital Apex/Middle Fossa Cerebrospinal Fluid Leak with a Nasoseptal Flap.

PubMed

Lucke-Wold, Brandon; Mendez, Gustavo; Cua, David; Akins, Paul; Gillham, Haley; Ciporen, Jeremy

2018-01-01

High flow orbital apex or middle fossa cerebrospinal fluid (CSF) leaks can be life threatening and complex to repair. These leaks associated with large dural defects are most commonly repaired with an open temporalis muscle patch or free flaps, but these flaps do not always stop the leak. A 65-year-old patient presented two years after orbital exenteration and radiation for squamous cell carcinoma. He developed multi-organism meningitis and pneumocephalus secondary to a large high-flow orbital apex/middle fossa CSF leak. To repair the leak, a combined endoscopic transorbital/endonasal approach with pedicled nasospetal flap and dermis fat graft was used. We describe the unique endoscopic technique that was used to treat the life threatening high flow orbital apex/middle fossa CSF leak. The technique allowed the use of the transposed pedicled flap, which is an alternative to the free flap in controlling CSF leak. Cisternogram post-operatively and clinical exam confirmed resolution of CSF leak. Although a critically ill patient at admission with a modified Rankin scale (MRS) of 5, he was discharged home on continued IV antibiotic therapy with a MRS of 3. Endoscopic evaluation at three months after treatment showed the effectiveness of the flap and he continued to improve clinically. This is the first case to describe a combined endoscopic transorbital and endonasal repair of high flow orbital apex/middle fossa CSF leak with a pedicled nasoseptal flap. These techniques can be utilized during initial reconstruction after orbital exenteration or as a salvage flap.

Hazardous Gas Leak Analysis in the Space Shuttle

NASA Technical Reports Server (NTRS)

Barile, Ronald G.

1991-01-01

Helium tests of the main propulsion system in the Space Shuttle and on hydrogen leaks are examined. The hazardous gas detection system (HGDS) in the mobile launch pad uses mass spectrometers (MS) to monitor the shuttle environment for leaks. The mass spectrometers are fed by long tubes to sample gas from the payload bay, mid-body, aft engine compartment, and external tank. The purpose is to improve the HGDS, especially in its potential for locating cryogen leaks. Pre-existing leak data was analyzed for transient information to determine if the leak location could be pinpointed from test data. A rapid response leak detection experiment was designed, built, and tested. Large eddies and vortices were visually seen with Schlieren imaging, and they were detected in the time plots of the various instruments. The response time of the MS was found in the range of 0.05 to 0.1 sec. Pulsed concentration waves were clearly detected at 25 cycles per sec by spectral analysis of MS data. One conclusion is that the backup HGDS sampling frequency should be increased above the present rate of 1 sample per second.

Spontaneous nasal cerebrospinal fluid leaks and empty sella syndrome: a clinical association.

PubMed

Schlosser, Rodney J; Bolger, William E

2003-01-01

Spontaneous, idiopathic nasal meningoencephaloceles are herniations of arachnoid/dura and cerebrospinal fluid (CSF) through anatomically fragile sites within the skull base. Empty sella syndrome occurs when intracranial contents herniate through the sellar diaphragm filling the sella turcica with CSF and giving the radiographic appearance of an absent pituitary gland. The objective of this study was to examine the association between spontaneous encephaloceles/CSF leaks and empty sella syndrome because of their similar clinical features and potential common pathophysiology. Retrospective. Sixteen patients were treated for spontaneous encephaloceles between 1996 and 2001. All 16 patients had associated CSF leaks. Five patients had multiple simultaneous encephaloceles. Fifteen patients with imaging of the sella turcica had empty (10 patients) or partially empty (5 patients) sellas. One patient did not have complete imaging of the sella. Three patients had lumbar punctures with measurement of CSF pressure during computed tomography cisternograms because of multiple skull base defects. Mean CSF pressure was 28.3 cm of water (range, 19-34 cm; normal, 0-15 cm). Thirteen of 16 patients (81%) were obese women (mean body mass index 35.9 kg/m2; normal, <25 kg/m2). Mean follow-up was 14.2 months with 100% success in closure of the defects after one procedure. Spontaneous meningoencephaloceles and CSF leaks are strongly associated with radiographic findings of an empty sella and suggest a common pathophysiology. The underlying condition probably represents a form of intracranial hypertension that exerts hydrostatic pressure at anatomically weakened sites within the skull base. Otolaryngologists should be familiar with this disease entity and the implications intracranial hypertension has on patient management.

Cerebrospinal fluid leaks and encephaloceles of temporal bone origin: nuances to diagnosis and management.

PubMed

Jeevan, Dhruve S; Ormond, D Ryan; Kim, Ana H; Meiteles, Lawrence Z; Stidham, Katrina R; Linstrom, Christopher; Murali, Raj

2015-04-01

Temporal bone encephalocele has become less common as the incidence of chronic mastoid infection and surgery for this condition has decreased. As a result, the diagnosis is often delayed, and the encephalocele is often an incidental finding. This situation can result in serious neurologic complications with patients presenting with cerebrospinal fluid leak and meningitis. We review the occurrence of, characteristics of, and repair experience with temporal encephaloceles from 2000-2012. We conducted a retrospective review of 32 patients undergoing combined mastoidectomy and middle cranial fossa craniotomy for the treatment of temporal encephalocele. The diagnosis of temporal encephalocele was made in all patients using high-resolution temporal bone computed tomography and magnetic resonance imaging. At the time of diagnosis, 12 patients had confirmed cerebrospinal fluid leak; other common presenting symptoms included hearing loss and ear fullness. Tegmen defect was most commonly due to chronic otitis media (n = 14). Of these patients, 8 had undergone prior mastoidectomy, suggesting an iatrogenic cause. Other etiologies included radiation exposure, congenital defects, and spontaneous defects. Additionally, 2 patients presented with meningitis; 1 patient had serious neurologic deficits resulting from venous infarction. The risk of severe neurologic complications after the herniation of intracranial contents through a tegmen defect necessitates prompt recognition and appropriate management. Computed tomography and magnetic resonance imaging aid in definitive diagnosis. A combined mastoid/middle fossa approach allows for sustainable repair with adequate exposure of defects and support of intracranial contents. Copyright © 2015 Elsevier Inc. All rights reserved.

Aerospace Payloads Leak Test Methodology

NASA Technical Reports Server (NTRS)

Lvovsky, Oleg; Grayson, Cynthia M.

2010-01-01

Pressurized and sealed aerospace payloads can leak on orbit. When dealing with toxic or hazardous materials, requirements for fluid and gas leakage rates have to be properly established, and most importantly, reliably verified using the best Nondestructive Test (NDT) method available. Such verification can be implemented through application of various leak test methods that will be the subject of this paper, with a purpose to show what approach to payload leakage rate requirement verification is taken by the National Aeronautics and Space Administration (NASA). The scope of this paper will be mostly a detailed description of 14 leak test methods recommended.

Development problem analysis of correlation leak detector’s software

NASA Astrophysics Data System (ADS)

Faerman, V. A.; Avramchuk, V. S.; Marukyan, V. M.

2018-05-01

In the article, the practical application and the structure of the correlation leak detectors’ software is studied and the task of its designing is analyzed. In the first part of the research paper, the expediency of the facilities development of correlation leak detectors for the following operating efficiency of public utilities exploitation is shown. The analysis of the functional structure of correlation leak detectors is conducted and its program software tasks are defined. In the second part of the research paper some development steps of the software package – requirement forming, program structure definition and software concept creation – are examined in the context of the usage experience of the hardware-software prototype of correlation leak detector.

40 CFR 60.562-2 - Standards: Equipment leaks of VOC.

Code of Federal Regulations, 2013 CFR

2013-07-01

... from bleed ports in existing pumps in light liquid service are not considered to be a leak as defined... feature of the pump whereby polymer fluid used to provide lubrication and/or cooling of the pump shaft exits the pump, thereby resulting in a visible leak of fluid. This exemption expires when the existing...

40 CFR 60.562-2 - Standards: Equipment leaks of VOC.

Code of Federal Regulations, 2014 CFR

2014-07-01

... from bleed ports in existing pumps in light liquid service are not considered to be a leak as defined... feature of the pump whereby polymer fluid used to provide lubrication and/or cooling of the pump shaft exits the pump, thereby resulting in a visible leak of fluid. This exemption expires when the existing...

40 CFR 60.562-2 - Standards: Equipment leaks of VOC.

Code of Federal Regulations, 2011 CFR

2011-07-01

... from bleed ports in existing pumps in light liquid service are not considered to be a leak as defined... feature of the pump whereby polymer fluid used to provide lubrication and/or cooling of the pump shaft exits the pump, thereby resulting in a visible leak of fluid. This exemption expires when the existing...

40 CFR 60.562-2 - Standards: Equipment leaks of VOC.

Code of Federal Regulations, 2012 CFR

2012-07-01

... from bleed ports in existing pumps in light liquid service are not considered to be a leak as defined... feature of the pump whereby polymer fluid used to provide lubrication and/or cooling of the pump shaft exits the pump, thereby resulting in a visible leak of fluid. This exemption expires when the existing...

Atmospheric emissions from the Deepwater Horizon spill constrain air-water partitioning, hydrocarbon fate, and leak rate

NASA Astrophysics Data System (ADS)

Ryerson, T. B.; Aikin, K. C.; Angevine, W. M.; Atlas, E. L.; Blake, D. R.; Brock, C. A.; Fehsenfeld, F. C.; Gao, R.-S.; de Gouw, J. A.; Fahey, D. W.; Holloway, J. S.; Lack, D. A.; Lueb, R. A.; Meinardi, S.; Middlebrook, A. M.; Murphy, D. M.; Neuman, J. A.; Nowak, J. B.; Parrish, D. D.; Peischl, J.; Perring, A. E.; Pollack, I. B.; Ravishankara, A. R.; Roberts, J. M.; Schwarz, J. P.; Spackman, J. R.; Stark, H.; Warneke, C.; Watts, L. A.

2011-04-01

The fate of deepwater releases of gas and oil mixtures is initially determined by solubility and volatility of individual hydrocarbon species; these attributes determine partitioning between air and water. Quantifying this partitioning is necessary to constrain simulations of gas and oil transport, to predict marine bioavailability of different fractions of the gas-oil mixture, and to develop a comprehensive picture of the fate of leaked hydrocarbons in the marine environment. Analysis of airborne atmospheric data shows massive amounts (˜258,000 kg/day) of hydrocarbons evaporating promptly from the Deepwater Horizon spill; these data collected during two research flights constrain air-water partitioning, thus bioavailability and fate, of the leaked fluid. This analysis quantifies the fraction of surfacing hydrocarbons that dissolves in the water column (˜33% by mass), the fraction that does not dissolve, and the fraction that evaporates promptly after surfacing (˜14% by mass). We do not quantify the leaked fraction lacking a surface expression; therefore, calculation of atmospheric mass fluxes provides a lower limit to the total hydrocarbon leak rate of 32,600 to 47,700 barrels of fluid per day, depending on reservoir fluid composition information. This study demonstrates a new approach for rapid-response airborne assessment of future oil spills.

Middle cranial fossa approach for the repair of spontaneous cerebrospinal fluid leaks to the middle ear.

PubMed

Altuna, Xabier; Navarro, Juan José; García, Leire; Ugarte, Ane; Thomas, Izaskun

Spontaneous cerebrospinal fluid (CSF) leaks to the middle ear due to tegmen tympani defects can result in hearing loss or hypoacusis and predispose to meningitis as well as other neurological complications. Surgical repair of the defect can be performed through a middle cranial fossa (MCF) approach or a transmastoid approach. We conducted a retrospective study of the patients in our Department due to a spontaneous CSF leak to the middle ear treated using a MCF approach during a 6-year period (2009-2014). Thirteen patients with spontaneous CSF leak to the middle ear were treated with this approach. The primary and first symptom in all of them was conductive hearing loss. In all cases, the defect or defects were closed in a multilayer manner using muscle, temporalis fascia and cortical bone. Minimum follow-up in this series was 14 months, with successful closure in all but one patient (who required reintervention). We found no intra- or postoperative complications due to the craniotomy, and the audiometry improved and normalised in all cases except for the failed case. The MCF approach with a multilayer closure of the defect is an effective technique for repairing spontaneous CSF leaks to the middle ear and for restoring hearing in these patients. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Otorrinolaringología y Cirugía de Cabeza y Cuello. All rights reserved.

Cerebrospinal fluid leak (image)

MedlinePlus

... brain and spinal cord by acting like a liquid cushion. The fluid allows the organs to be buoyant protecting them from blows or other trauma. Inside the skull the cerebrospinal fluid is contained by the dura which covers ...

Cerebrospinal fluid leaks following spinal or posterior fossa surgery: use of fat grafts for prevention and repair.

PubMed

Black, P

2000-01-01

Cerebrospinal fluid (CSF) leaks are relatively common following spinal or posterior fossa surgery. A midline dural tear in the spine is readily repaired by direct application of a suture. However, far-lateral or ventral dural tears are problematic. Fat is an ideal sealant because it is impermeable to water. In this paper the author reports his experience with using fat grafts for the prevention or repair of CSF leaks and proposes a technique in which a large sheet of fat, harvested from the patient's subcutaneous layer, is used to cover not only the dural tear(s) but all of the exposed dura and is tucked into the lateral recess. This procedure prevents CSF from seeping around the fat, which may be tacked to the dura with a few sutures. Fibrin glue is spread on the surface of the fat and is further covered with Surgicel or Gelfoam. For ventral dural tears (associated with procedures in which disc material is excised), fat is packed into the disc space to seal off the ventral dural leak. Leaks in the posterior fossa are managed similarly to those in the spine. Dural suture lines, following suboccipital or spinal intradural exploration, are prophylactically protected from CSF leakage in the same manner. With one exception, 27 dural tears noted during 1650 spinal procedures were successfully repaired using this technique. There was one case of postoperative CSF leakage in 150 cases in which intradural exploration for tumor or other lesions was undertaken. Both postoperative CSF leaks were controlled by applying additional skin sutures. The use of a fat graft is recommended as a rapid, effective means of prevention and repair of CSF leaks following posterior fossa and spinal surgery.

40 CFR 61.135 - Standard: Equipment leaks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Emissions from Coke By-Product Recovery Plants § 61.135 Standard: Equipment leaks. (a) Each owner or... benzene service. (d) Each exhauster shall be monitored quarterly to detect leaks by the methods specified... stuffing box pressure; or (ii) Equipped with a barrier fluid system that is connected by a closed vent...

Reliable Intraoperative Repair Nuances of Cerebrospinal Fluid Leak in Anterior Cervical Spine Surgery and Review of the Literature.

PubMed

Mitchell, Bartley D; Verla, Terence; Reddy, Duemani; Winnegan, Lona; Omeis, Ibrahim

2016-04-01

Cerebrospinal fluid (CSF) leak during anterior cervical spine surgery can lead to complications, including wound breakdown, meningitis, headaches, need for lumbar drain, or additional surgery. These leaks can be difficult to manage given the limited field of view and lack of deep access. Herein, we describe 8 consecutive patients who underwent intraoperative repair of CSF leak, with no postoperative evidence of wound dehiscence or drainage. A retrospective review was performed on 8 cases where CSF leak was encountered during an anterior cervical spine surgery. Patients had ossification of the posterior longitudinal ligament, intradural disk herniation, or dural ectasia. Intraoperative repair was as follows. First, CSF was drained to low pressure, and durotomy was covered by dural substitute and sealant agent. Then the interbody graft used was manually undersized in the anteroposterior dimension to allow for expansion of the agents used. Anterior instrumentation was then performed. Finally, a wound drain was anchored to a biologic bag for shoulder level passive drainage. In all 8 cases, there were no cases of wound dehiscence or CSF leak using this strategy. Likewise, there was no evidence of cord compression or neurologic deficits. No meningitis or persistent headaches were reported, and there was no need for lumbar drain placement at any time postoperatively. Once durotomy is encountered during anterior spine surgery, draining the CSF to a low pressure followed by dural substitute with a sealing agent, followed by a smaller anteroposterior size graft is an effective strategy of preventing complications in an inescapable problem. Copyright © 2016 Elsevier Inc. All rights reserved.

Innovative real CSF leak simulation model for rhinology training: human cadaveric design.

PubMed

AlQahtani, Abdulaziz A; Albathi, Abeer A; Alhammad, Othman M; Alrabie, Abdulkarim S

2018-04-01

To study the feasibility of designing a human cadaveric simulation model of real CSF leak for rhinology training. The laboratory investigation took place at the surgical academic center of Prince Sultan Military Medical City between 2016 and 2017. Five heads of human cadaveric specimens were cannulated into the intradural space through two frontal bone holes. Fluorescein-dyed fluid was injected intracranialy, then endoscopic endonasal iatrogenic skull base defect was created with observation of fluid leak, followed by skull base reconstruction. The outcome measures included subjective assessment of integrity of the design, the ability of creating real CSF leak in multiple site of skull base and the possibility of watertight closure by various surgical techniques. The fluid filled the intradural space in all specimens without spontaneous leak from skull base or extra sinus areas. Successfully, we demonstrated fluid leak from all areas after iatrogenic defect in the cribriform plate, fovea ethmoidalis, planum sphenoidale sellar and clival regions. Watertight closure was achieved in all defects using different reconstruction techniques (overly, underlay and gasket seal closure). The design is simulating the real patient with CSF leak. It has potential in the learning process of acquiring and maintaining the surgical skills of skull base reconstruction before direct involvement of the patient. This model needs further evaluation and competence measurement as training tools in rhinology training.

Evaluation of Spontaneous Spinal Cerebrospinal Fluid Leaks Disease by Computerized Image Processing.

PubMed

Yıldırım, Mustafa S; Kara, Sadık; Albayram, Mehmet S; Okkesim, Şükrü

2016-05-17

Spontaneous Spinal Cerebrospinal Fluid Leaks (SSCFL) is a disease based on tears on the dura mater. Due to widespread symptoms and low frequency of the disease, diagnosis is problematic. Diagnostic lumbar puncture is commonly used for diagnosing SSCFL, though it is invasive and may cause pain, inflammation or new leakages. T2-weighted MR imaging is also used for diagnosis; however, the literature on T2-weighted MRI states that findings for diagnosis of SSCFL could be erroneous when differentiating the diseased and control. One another technique for diagnosis is CT-myelography, but this has been suggested to be less successful than T2-weighted MRI and it needs an initial lumbar puncture. This study aimed to develop an objective, computerized numerical analysis method using noninvasive routine Magnetic Resonance Images that can be used in the evaluation and diagnosis of SSCFL disease. Brain boundaries were automatically detected using methods of mathematical morphology, and a distance transform was employed. According to normalized distances, average densities of certain sites were proportioned and a numerical criterion related to cerebrospinal fluid distribution was calculated. The developed method was able to differentiate between 14 patients and 14 control subjects significantly with p = 0.0088 and d = 0.958. Also, the pre and post-treatment MRI of four patients was obtained and analyzed. The results were differentiated statistically (p = 0.0320, d = 0.853). An original, noninvasive and objective diagnostic test based on computerized image processing has been developed for evaluation of SSCFL. To our knowledge, this is the first computerized image processing method for evaluation of the disease. Discrimination between patients and controls shows the validity of the method. Also, post-treatment changes observed in four patients support this verdict.

Spinal Cord Herniation After Cervical Corpectomy with Cerebrospinal Fluid Leak: Case Report and Review of the Literature.

PubMed

Guppy, Kern H; Silverthorn, James W

2017-04-01

Spinal cord herniation (SCH) is rare, is mostly idiopathic, and occurs predominantly in the thoracic spine. SCH is less common in the cervical spine and has been reported after posterior cervical spine surgery associated with the development of pseudomeningoceles. Two cases of SCH have been reported after anterior cervical corpectomies for ossified posterior longitudinal ligament with cerebrospinal fluid (CSF) leaks. We report the third such case, but the first in a patient without ossified posterior longitudinal ligament (degenerative disc disease and pseudarthrosis). A 56-year-old woman presented with bilateral arm pain and weakness. She had undergone 3 previous anterior cervical spine surgeries at an outside medical center with the most recent 7 years ago with C5 and C6 corpectomies and fusion with a persistent CSF leak. Magnetic resonance imaging and computed tomography myelography showed spinal cord herniation through the mesh cage at C6. The patient underwent a redo C5 and C6 corpectomy with untethering of the spinal cord. The patient was asymptomatic 2 years later. This is the first reported case of anterior cervical SCH in a patient without ossified posterior longitudinal ligament after multiple anterior cervical fusions including a cervical corpectomy for pseudarthrosis with a CSF leak. We hypothesize that persistent CSF leak causes a pressure gradient across the dura mater through the cage to the lower pressure in the retropharyngeal space, which led to herniation of the spinal cord into the anterior cage. We review the literature and discuss the treatment choices for anterior cervical SCH. Copyright © 2017 Elsevier Inc. All rights reserved.

Cerebrospinal fluid otorhinorrhea due to cochlear dysplasias.

PubMed

Syal, Rajan; Tyagi, Isha; Goyal, Amit

2005-07-01

Cochlear dysplasia associated with defect in stapes footplate can be a cause of cerebrospinal fluid leak. Repair of cerebrospinal fluid leak in these cases is usually done by packing the vestibule with muscle or fascia. This traditional method of repair has 30-60% failure rate. Cerebrospinal fluid leak in four such patients was successfully repaired using multiple layer packing of vestibule, reinforced by pedicle temporalis muscle graft. Intraoperatively continuous lumbar drain was done. Magnetic resonance imaging of inner ear using 3D FSE T2WI and 3D FIESTA sequences was found helpful noninvasive investigation to localize site and route of cerebrospinal fluid leak.

Milestone Report #2: Direct Evaporator Leak and Flammability Analysis Modifications and Optimization of the Organic Rankine Cycle to Improve the Recovery of Waste Heat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guillen, Donna Post

2013-09-01

The direct evaporator is a simplified heat exchange system for an Organic Rankine Cycle (ORC) that generates electricity from a gas turbine exhaust stream. Typically, the heat of the exhaust stream is transferred indirectly to the ORC by means of an intermediate thermal oil loop. In this project, the goal is to design a direct evaporator where the working fluid is evaporated in the exhaust gas heat exchanger. By eliminating one of the heat exchangers and the intermediate oil loop, the overall ORC system cost can be reduced by approximately 15%. However, placing a heat exchanger operating with a flammablemore » hydrocarbon working fluid directly in the hot exhaust gas stream presents potential safety risks. The purpose of the analyses presented in this report is to assess the flammability of the selected working fluid in the hot exhaust gas stream stemming from a potential leak in the evaporator. Ignition delay time for cyclopentane at temperatures and pressure corresponding to direct evaporator operation was obtained for several equivalence ratios. Results of a computational fluid dynamic analysis of a pinhole leak scenario are given.« less

Cerebrospinal Fluid Leak at Percutaneous Exit of Ventricular Catheter as a Crucial Risk Factor for External Ventricular Drainage-Related Infection in Adult Neurosurgical Patients.

PubMed

Park, Jaechan; Choi, Yeon-Ju; Ohk, Boram; Chang, Hyun-Ha

2018-01-01

The placement of a ventricular catheter for temporary cerebrospinal fluid (CSF) diversion is associated with a considerable risk of CSF infection. The authors investigated the effect of a CSF leak on CSF-related infection and the predisposing factors for a CSF leak. Fifty-two patients who underwent external ventricular drainage (EVD) for acute hydrocephalus associated with a subarachnoid hemorrhage or intraventricular hemorrhage (IVH) were enrolled in this prospective study. A CSF leak-detection paper (small sterilized filter paper) was applied at the percutaneous catheter exit site to check for any bloody CSF leak. In addition, radiologic and clinical data were collected. Four of the 52 patients (7.7%) developed an EVD-related CSF infection from organisms including Staphylococcus epidermidis (n = 3) and Staphylococcus hominis (n = 1). A prolonged CSF leak >1 day was detected in 9 patients (17.3%) and revealed as a significant risk factor for CSF infection with a 44.4% positive predictive value. Moreover, an IVH >10 mL was found in 11 patients (21.2%) and revealed as a significant predisposing factor for a CSF leak at the percutaneous catheter exit. A prolonged CSF leak for >1 day at the percutaneous catheter exit site is a crucial risk factor for EVD-related CSF infection and an IVH >10 mL is a predisposing factor for a CSF leak. Copyright © 2017 Elsevier Inc. All rights reserved.

Transmastoid approach to temporal bone cerebrospinal fluid leaks.

PubMed

Oliaei, Sepehr; Mahboubi, Hossein; Djalilian, Hamid R

2012-01-01

The aim of the study was to evaluate various presentations and treatment options for spontaneous cerebrospinal fluid (CSF) leakage originating in the temporal bone. Clinical data and imaging results for 18 ears (15 patients) presenting with spontaneous CSF leakage originating in the temporal bone were reviewed. Average follow-up period was 13.5 months. The main outcome measure was presence of persistent CSF leak postoperatively. A standard postauricular mastoidectomy was performed. Fifteen patients diagnosed with spontaneous CSF leakage over an 8-year period including 3 treated for bilateral disease were included in the study. The age ranged between 33 and 83 years. Presenting symptoms included serous otitis media (44%), persistent otorrhea after tympanostomy tube placement (28%), and meningitis (28%). Preoperative diagnosis was made using imaging studies and was substantiated by observation of CSF leakage and dural herniation intraoperatively. Treatment was eustachian tube plugging (5%), mastoidectomy with fat obliteration (61%), middle fossa approach with extradural (17%), intradural repair (5%), or combined middle fossa and transmastoid (TM) approach (11%). Successful treatment was obtained in 17 of the 18 cases. The last 9 patients in the series underwent TM approach alone for repair with no treatment failures. Repair of defects in tegmen mastoideum and posterior fossa can be successfully achieved on an outpatient basis without regard to size and multitude of defects via TM approach. This approach obviates the need for a craniotomy or lumbar drain. Copyright © 2012 Elsevier Inc. All rights reserved.

Preservation of the Myofascial Cuff During Posterior Fossa Surgery to Reduce the Rate of Pseudomeningocele Formation and Cerebrospinal Fluid Leak: A Technical Note

PubMed Central

Felbaum, Daniel R; Anaizi, Amjad; Mason, Robert B; Jean, Walter C; Voyadzis, Jean M

2016-01-01

Introduction: Suboccipital craniotomy is a workhorse neurosurgical operation for approaching the posterior fossa but carries a high risk of pseudomeningocele and cerebrospinal fluid (CSF) leak. We describe our experience with a simple T-shaped fascial opening that preserves the occipital myofascial cuff as compared to traditional methods to reduce this risk. Methods: A single institution, retrospective review of prospectively collected database was performed of patients that underwent a suboccipital craniectomy or craniotomy. Patient data was reviewed for craniotomy or craniectomy, dural graft, and/or sealant use as well as CSF complications. A pseudomeningocele was defined as a subcutaneous collection of cerebrospinal fluid palpable clinically and confirmed on imaging. A CSF leak was defined as a CSF-cutaneous fistula manifested by CSF leaking through the wound. All patients underwent regular postoperative visits of two weeks, one month, and three months. Results: Our retrospective review identified 33 patients matching the inclusion criteria. Overall, our cohort had a 21% (7/33) rate of clinical and radiographic pseudomeningocele formation with 9% (3/33) requiring surgical revision or a separate procedure. The rate of clinical and radiographic pseudomeningocele formation in the myofascial cuff preservation technique was less than standard techniques (12% and 31%, respectively). Revision or further surgical procedures were also reduced in the myofascial cuff preservation technique vs. the standard technique (6% vs 13%). Conclusions: Preservation of the myofascial cuff during posterior fossa surgery is a simple and adoptable technique that reduces the rate of pseudomeningocele formation and CSF leak as compared with standard techniques.   PMID:28133584

Preservation of the Myofascial Cuff During Posterior Fossa Surgery to Reduce the Rate of Pseudomeningocele Formation and Cerebrospinal Fluid Leak: A Technical Note.

PubMed

Felbaum, Daniel R; Mueller, Kyle; Anaizi, Amjad; Mason, Robert B; Jean, Walter C; Voyadzis, Jean M

2016-12-28

 Suboccipital craniotomy is a workhorse neurosurgical operation for approaching the posterior fossa but carries a high risk of pseudomeningocele and cerebrospinal fluid (CSF) leak. We describe our experience with a simple T-shaped fascial opening that preserves the occipital myofascial cuff as compared to traditional methods to reduce this risk.  A single institution, retrospective review of prospectively collected database was performed of patients that underwent a suboccipital craniectomy or craniotomy. Patient data was reviewed for craniotomy or craniectomy, dural graft, and/or sealant use as well as CSF complications. A pseudomeningocele was defined as a subcutaneous collection of cerebrospinal fluid palpable clinically and confirmed on imaging. A CSF leak was defined as a CSF-cutaneous fistula manifested by CSF leaking through the wound. All patients underwent regular postoperative visits of two weeks, one month, and three months.  Our retrospective review identified 33 patients matching the inclusion criteria. Overall, our cohort had a 21% (7/33) rate of clinical and radiographic pseudomeningocele formation with 9% (3/33) requiring surgical revision or a separate procedure. The rate of clinical and radiographic pseudomeningocele formation in the myofascial cuff preservation technique was less than standard techniques (12% and 31%, respectively). Revision or further surgical procedures were also reduced in the myofascial cuff preservation technique vs. the standard technique (6% vs 13%).  Preservation of the myofascial cuff during posterior fossa surgery is a simple and adoptable technique that reduces the rate of pseudomeningocele formation and CSF leak as compared with standard techniques.

Fluid leakage detector for vacuum applications

NASA Technical Reports Server (NTRS)

Nguyen, Bich Ngoc (Inventor); Farkas, Tibor (Inventor); Kim, Brian Byungkyu (Inventor)

2002-01-01

A leak detection system for use with a fluid conducting system in a vacuum environment, such as space, is described. The system preferably includes a mesh-like member substantially disposed about the fluid conducting system, and at least one sensor disposed within the mesh-like member. The sensor is capable of detecting a decrease in temperature of the mesh-like member when a leak condition causes the fluid of the fluid conducting system to freeze when exposed to the vacuum environment. Additionally, a signal processor in preferably in communication with the sensor. The sensor transmits an electrical signal to the signal processor such that the signal processor is capable of indicating the location of the fluid leak in the fluid conducting system.

Dural diverticulum with a symptomatic cerebrospinal fluid leak.

PubMed

Armstrong, Nicholas; Williamson, Clinton; Williamson, Natalie; Fortes, Manuel; Tjauw, Iwan; Vij, Vikas; Trojan, Ryan

2016-03-01

A case report of a 63-year-old female patient with a cervical spinal dural diverticulum and intracranial hypotension secondary to a symptomatic CSF leak after minor trauma. The patient responded well after the cervical approach epidural blood patch procedure.

Mitigated Transfer Line Leaks that Result in Surface Pools and Spray Leaks into Pits

DOE Office of Scientific and Technical Information (OSTI.GOV)

HEY, B.E.

This analysis provides radiological and toxicological consequence calculations for postulated mitigated leaks during transfers of six waste compositions. Leaks in Cleanout Boxes equipped with supplemental covers and leaks in pits are analyzed.

Method and means of passive detection of leaks in buried pipes

DOEpatents

Claytor, T.

1979-10-30

A method and means for passive detection of a leak in a buried pipe containing fluid under pressure includes a plurality of acoustic detectors that are placed in contact with the pipe. Noise produced by the leak is detected by the detectors, and the detected signals are correlated to locate the leak. In one embodiment of the invention two detectors are placed at different locations to locate a leak between them. In an alternate embodiment two detectors of different waves are placed at substantially the same location to determine the distance of the leak from the location.

Method and means of passive detection of leaks in buried pipes

DOEpatents

Claytor, Thomas N.

1981-01-01

A method and means for passive detection of a leak in a buried pipe containing fluid under pressure includes a plurality of acoustic detectors that are placed in contact with the pipe. Noise produced by the leak is detected by the detectors, and the detected signals are correlated to locate the leak. In one embodiment of the invention two detectors are placed at different locations to locate a leak between them. In an alternate embodiment two detectors of different waves are placed at substantially the same location to determine the distance of the leak from the location.

Intraoperative leak testing has no correlation with leak after laparoscopic sleeve gastrectomy.

PubMed

Sethi, Monica; Zagzag, Jonathan; Patel, Karan; Magrath, Melissa; Somoza, Eduardo; Parikh, Manish S; Saunders, John K; Ude-Welcome, Aku; Schwack, Bradley F; Kurian, Marina S; Fielding, George A; Ren-Fielding, Christine J

2016-03-01

Staple line leak is a serious complication of sleeve gastrectomy. Intraoperative methylene blue and air leak tests are routinely used to evaluate for leak; however, the utility of these tests is controversial. We hypothesize that the practice of routine intraoperative leak testing is unnecessary during sleeve gastrectomy. A retrospective cohort study was designed using a prospectively collected database of seven bariatric surgeons from two institutions. All patients who underwent sleeve gastrectomy from March 2012 to November 2014 were included. The performance of intraoperative leak testing and the type of test (air or methylene blue) were based on surgeon preference. Data obtained included BMI, demographics, comorbidity, presence of intraoperative leak test, result of test, and type of test. The primary outcome was leak rate between the leak test (LT) and no leak test (NLT) groups. SAS version 9.4 was used for univariate and multivariate analyses. A total of 1550 sleeve gastrectomies were included; most were laparoscopic (99.8%), except for one converted and two open cases. Routine intraoperative leak tests were performed in 1329 (85.7%) cases, while 221 (14.3%) did not have LTs. Of the 1329 cases with LTs, there were no positive intraoperative results. Fifteen (1%) patients developed leaks, with no difference in leak rate between the LT and NLT groups (1 vs. 1%, p = 0.999). After adjusting for baseline differences between the groups with a propensity analysis, the observed lack of association between leak and intraoperative leak test remained. In this cohort, leaks presented at a mean of 17.3 days postoperatively (range 1-67 days). Two patients with staple line leaks underwent repeat intraoperative leak testing at leak presentation, and the tests remained negative. Intraoperative leak testing has no correlation with leak due to laparoscopic sleeve gastrectomy and is not predictive of the later development of staple line leak.

Modeling the Risk of Fire/Explosion Due to Oxidizer/Fuel Leaks in the Ares I Interstage

NASA Technical Reports Server (NTRS)

Ring, Robert W.; Stott, James E.; Hales, Christy

2008-01-01

A significant flight hazard associated with liquid propellants, such as those used in the upper stage of NASA's new Ares I launch vehicle, is the possibility of leakage of hazardous fluids resulting in a catastrophic fire/explosion. The enclosed and vented interstage of the Ares I contains numerous oxidizer and fuel supply lines as well as ignition sources. The potential for fire/explosion due to leaks during ascent depends on the relative concentrations of hazardous and inert fluids within the interstage along with other variables such as pressure, temperature, leak rates, and fluid outgasing rates. This analysis improves on previous NASA Probabilistic Risk Assessment (PRA) estimates of the probability of deflagration, in which many of the variables pertinent to the problem were not explicitly modeled as a function of time. This paper presents the modeling methodology developed to analyze these risks.

Lack of causal association between spontaneous intracranial hypotension and cranial cerebrospinal fluid leaks.

PubMed

Schievink, Wouter I; Schwartz, Marc S; Maya, M Marcel; Moser, Franklin G; Rozen, Todd D

2012-04-01

Spontaneous intracranial hypotension is an important cause of headaches and an underlying spinal CSF leak can be demonstrated in most patients. Whether CSF leaks at the level of the skull base can cause spontaneous intracranial hypotension remains a matter of controversy. The authors' aim was to examine the frequency of skull base CSF leaks as the cause of spontaneous intracranial hypotension. Demographic, clinical, and radiological data were collected from a consecutive group of patients evaluated for spontaneous intracranial hypotension during a 9-year period. Among 273 patients who met the diagnostic criteria for spontaneous intracranial hypotension and 42 who did not, not a single instance of CSF leak at the skull base was encountered. Clear nasal drainage was reported by 41 patients, but a diagnosis of CSF rhinorrhea could not be established. Four patients underwent exploratory surgery for presumed CSF rhinorrhea. In addition, the authors treated 3 patients who had a postoperative CSF leak at the skull base following the resection of a cerebellopontine angle tumor and developed orthostatic headaches; spinal imaging, however, demonstrated the presence of a spinal source of CSF leakage in all 3 patients. There is no evidence for an association between spontaneous intracranial hypotension and CSF leaks at the level of the skull base. Moreover, the authors' study suggests that a spinal source for CSF leakage should even be suspected in patients with orthostatic headaches who have a documented skull base CSF leak.

Lumbar Drains Decrease the Risk of Postoperative Cerebrospinal Fluid Leak Following Endonasal Endoscopic Surgery for Suprasellar Meningiomas in Patients With High Body Mass Index.

PubMed

Cohen, Salomon; Jones, Samuel H; Dhandapani, Sivashanmugam; Negm, Hazem M; Anand, Vijay K; Schwartz, Theodore H

2018-01-01

Postoperative cerebrospinal fluid (CSF) leak is a persistent, albeit much less prominent, complication following endonasal endoscopic surgery. The pathology with highest risk is suprasellar meningiomas. A postoperative lumbar drain (LD) is used to decrease the risk of CSF leak but is not universally accepted. To compare the rates of postoperative CSF leak between patients with and without LD who underwent endonasal endoscopic surgical resection of suprasellar meningiomas. A consecutive series of newly diagnosed suprasellar meningiomas was drawn from a prospectively acquired database of endonasal endoscopic surgeries at our institution. An intraoperative, preresection LD was placed and left open at 5 cc/h for ∼48 h. In a subset of patients, the LD could not be placed. Rates of postoperative CSF leak were compared between patients with and without an LD. Twenty-five patients underwent endonasal endoscopic surgical resection of suprasellar meningiomas. An LD could not be placed in 2 patients. There were 2 postoperative CSF leaks (8%), both of which occurred in the patients who did not have an LD (P = .0033). The average body mass index (BMI) of the patients in whom the LD could not be placed was 39.1 kg/m2, compared with 27.6 kg/m2 for those in whom the LD could be placed (P = .009). In the subgroup of obese patients (BMI > 30 kg/m2), LD placement was protective against postoperative CSF leak (P = .022). The inability to place an LD in patients with obesity is a risk factor for postoperative CSF leak. An LD may be useful to prevent postoperative CSF leak, particularly in patients with elevated BMI. Copyright © 2017 by the Congress of Neurological Surgeons

Leaks, Lumps, and Lines: Stigma and Women's Bodies

ERIC Educational Resources Information Center

Chrisler, Joan C.

2011-01-01

Women's bodies have often been positioned in art and popular culture as monstrous or defiled and women's bodily products (e.g., menstrual fluid, breast milk) as disgusting. This framing has led to the stigmatization of aspects of women's bodies (e.g., leaking fluids, lumps of fat, and lines in the skin that indicate aging), especially those…

Technique for detecting liquid metal leaks

DOEpatents

Bauerle, James E.

1979-01-01

In a system employing flowing liquid metal as a heat transfer medium in contact with tubular members containing a working fluid, i.e., steam, liquid metal leaks through the wall of the tubular member are detected by dislodging the liquid metal compounds forming in the tubular member at the leak locations and subsequently transporting the dislodged compound in the form of an aerosol to a detector responsive to the liquid metal compound. In the application to a sodium cooled tubular member, the detector would consist of a sodium responsive device, such as a sodium ion detector.

U.S. strategic petroleum reserve Big Hill 114 leak analysis 2012.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lord, David L.; Roberts, Barry L.; Lord, Anna C. Snider

2013-06-01

This report addresses recent well integrity issues related to cavern 114 at the Big Hill Strategic Petroleum Reserve site. DM Petroleum Operations, M&O contractor for the U.S. Strategic Petroleum Reserve, recognized an apparent leak in Big Hill cavern well 114A in late summer, 2012, and provided written notice to the State of Texas as required by law. DM has since isolated the leak in well A with a temporary plug, and is planning on remediating both 114 A- and B-wells with liners. In this report Sandia provides an analysis of the apparent leak that includes: (i) estimated leak volume, (ii)more » recommendation for operating pressure to maintain in the cavern between temporary and permanent fixes for the well integrity issues, and (iii) identification of other caverns or wells at Big Hill that should be monitored closely in light of the sequence of failures there in the last several years.« less

Sensitivity of MRI of the spine compared with CT myelography in orthostatic headache with CSF leak.

PubMed

Starling, Amaal; Hernandez, Fatima; Hoxworth, Joseph M; Trentman, Terrence; Halker, Rashmi; Vargas, Bert B; Hastriter, Eric; Dodick, David

2013-11-12

To investigate the sensitivity of MRI of the spine compared with CT myelography (CTM) in detecting CSF leaks. Between July 1998 and October 2010, 12 patients with orthostatic headache and a CTM-confirmed spinal CSF leak underwent an MRI of the spine with and without contrast. Using CTM as the gold standard, we retrospectively investigated the sensitivity of spinal MRI in detecting a CSF leak. Eleven of 12 patients with a CSF leak documented by CTM also had extradural fluid collections on spinal MRI (sensitivity 91.7%). Six patients with extradural fluid collections on spinal MRI also had spinal dural enhancement. When compared with the gold standard of CTM, MRI of the spine appears to be a sensitive and less invasive imaging modality for detecting a spinal CSF leak, suggesting that MRI of the spine should be the imaging modality of first choice for the detection of spinal CSF leaks.

Ammonia Leak Locator Study

NASA Technical Reports Server (NTRS)

Dodge, Franklin T.; Wuest, Martin P.; Deffenbaugh, Danny M.

1995-01-01

The thermal control system of International Space Station Alpha will use liquid ammonia as the heat exchange fluid. It is expected that small leaks (of the order perhaps of one pound of ammonia per day) may develop in the lines transporting the ammonia to the various facilities as well as in the heat exchange equipment. Such leaks must be detected and located before the supply of ammonia becomes critically low. For that reason, NASA-JSC has a program underway to evaluate instruments that can detect and locate ultra-small concentrations of ammonia in a high vacuum environment. To be useful, the instrument must be portable and small enough that an astronaut can easily handle it during extravehicular activity. An additional complication in the design of the instrument is that the environment immediately surrounding ISSA will contain small concentrations of many other gases from venting of onboard experiments as well as from other kinds of leaks. These other vapors include water, cabin air, CO2, CO, argon, N2, and ethylene glycol. Altogether, this local environment might have a pressure of the order of 10(exp -7) to 10(exp -6) torr. Southwest Research Institute (SwRI) was contracted by NASA-JSC to provide support to NASA-JSC and its prime contractors in evaluating ammonia-location instruments and to make a preliminary trade study of the advantages and limitations of potential instruments. The present effort builds upon an earlier SwRI study to evaluate ammonia leak detection instruments [Jolly and Deffenbaugh]. The objectives of the present effort include: (1) Estimate the characteristics of representative ammonia leaks; (2) Evaluate the baseline instrument in the light of the estimated ammonia leak characteristics; (3) Propose alternative instrument concepts; and (4) Conduct a trade study of the proposed alternative concepts and recommend promising instruments. The baseline leak-location instrument selected by NASA-JSC was an ion gauge.

Intraoperative air leak measured after lobectomy is associated with postoperative duration of air leak.

PubMed

Brunelli, Alessandro; Salati, Michele; Pompili, Cecilia; Gentili, Paolo; Sabbatini, Armando

2017-11-01

To verify the association between the air leak objectively measured intraoperatively (IAL) using the ventilator and the air leak duration after pulmonary lobectomy. Prospective analysis on 111 patients submitted to pulmonary lobectomy (33 by video-assisted thoracic surgery). After resection, objective assessment of air leak (in milliliter per minute) was performed before closure of the chest by measuring the difference between a fixed inspired and expired volume, using a tidal volume of 8 ml/kg, a respiratory rate of 10 and a positive-end expiratory pressure of 5 cmH2O. A multivariable analysis was performed for identifying factors associated with duration of postoperative air leak. Average IAL was 158 ml/min (range 0-1500 ml/min). The best cut-off (receiver-operating characteristics analysis) associated with air leak longer than 5 days was 500 ml/min. Nine patients had IAL >500 ml/min (8%). They had a longer duration of postoperative air leak compared with those with a lower IAL (mean values, 10.1 days, SD 8.8 vs 1.5 days, SD 4.9 P < 0.001). The following variables remained associated with days of air leak duration after multivariable regression: left side resection (P = 0.018), upper site resection (P = 0.031) and IAL >500 ml/min (P < 0.001). The following equation estimating the days of air leak duration was generated: 1.7 + 2.4 × left side + 2.2 × upper site + 8.8 × IAL >500. The air leak measurement using the ventilator parameters after lung resection may assist in estimating the risk of postoperative prolonged air leak. An IAL > 500 ml/min may warrant the use of intraoperative preventative measures, particularly after video-assisted thoracic surgery lobectomy where a submersion test is often unreliable. © 2017 European Society of Cardiology and European Atherosclerosis Association. All rights reserved. For permissions please email: journals.permissions@oup.com.

Real-Time Model-Based Leak-Through Detection within Cryogenic Flow Systems

NASA Technical Reports Server (NTRS)

Walker, M.; Figueroa, F.

2015-01-01

The timely detection of leaks within cryogenic fuel replenishment systems is of significant importance to operators on account of the safety and economic impacts associated with material loss and operational inefficiencies. Associated loss in control of pressure also effects the stability and ability to control the phase of cryogenic fluids during replenishment operations. Current research dedicated to providing Prognostics and Health Management (PHM) coverage of such cryogenic replenishment systems has focused on the detection of leaks to atmosphere involving relatively simple model-based diagnostic approaches that, while effective, are unable to isolate the fault to specific piping system components. The authors have extended this research to focus on the detection of leaks through closed valves that are intended to isolate sections of the piping system from the flow and pressurization of cryogenic fluids. The described approach employs model-based detection of leak-through conditions based on correlations of pressure changes across isolation valves and attempts to isolate the faults to specific valves. Implementation of this capability is enabled by knowledge and information embedded in the domain model of the system. The approach has been used effectively to detect such leak-through faults during cryogenic operational testing at the Cryogenic Testbed at NASA's Kennedy Space Center.

Analysis of various tracts of mastoid air cells related to CSF leak after the anterior transpetrosal approach.

PubMed

Tamura, Ryota; Tomio, Ryosuke; Mohammad, Farrag; Toda, Masahiro; Yoshida, Kazunari

2018-03-16

OBJECTIVE The anterior transpetrosal approach (ATPA) was established in 1984 and has been particularly effective for petroclival tumors. Although some complications associated with this approach, such as venous hemorrhage in the temporal lobe and nervous disturbances, have been resolved over the years, the incidence rate of CSF leaks has not greatly improved. In this study, some varieties of air cell tracts that are strongly related to CSF leaks are demonstrated. In addition, other pre- and postoperative risk factors for CSF leakage after ATPA are discussed. METHODS Preoperative and postoperative target imaging of the temporal bone was performed in a total of 117 patients who underwent ATPA, and various surgery-related parameters were analyzed. RESULTS The existence of air cells at the petrous apex, as well as fluid collection in the mastoid antrum detected by a postoperative CT scan, were possible risk factors for CSF leakage. Tracts that directly connected to the antrum from the squamous part of the temporal bone and petrous apex, rather than through numerous air cells, were significantly related to CSF leak and were defined as "direct tract." All patients with a refractory CSF leak possessed "unusual tracts" that connected to the attic, tympanic cavity, or eustachian tube, rather than through the mastoid antrum. CONCLUSIONS Preoperative assessment of petrous pneumatization types is necessary to prevent CSF leaks. Direct and unusual tracts are particularly strong risk factors for CSF leaks.

Simulated spinal cerebrospinal fluid leak repair: an educational model with didactic and technical components.

PubMed

Ghobrial, George M; Anderson, Paul A; Chitale, Rohan; Campbell, Peter G; Lobel, Darlene A; Harrop, James

2013-10-01

In the era of surgical resident work hour restrictions, the traditional apprenticeship model may provide fewer hours for neurosurgical residents to hone technical skills. Spinal dura mater closure or repair is 1 skill that is infrequently encountered, and persistent cerebrospinal fluid leaks are a potential morbidity. To establish an educational curriculum to train residents in spinal dura mater closure with a novel durotomy repair model. The Congress of Neurological Surgeons has developed a simulation-based model for durotomy closure with the ongoing efforts of their simulation educational committee. The core curriculum consists of didactic training materials and a technical simulation model of dural repair for the lumbar spine. Didactic pretest scores ranged from 4/11 (36%) to 10/11 (91%). Posttest scores ranged from 8/11 (73%) to 11/11 (100%). Overall, didactic improvements were demonstrated by all participants, with a mean improvement between pre- and posttest scores of 1.17 (18.5%; P = .02). The technical component consisted of 11 durotomy closures by 6 participants, where 4 participants performed multiple durotomies. Mean time to closure of the durotomy ranged from 490 to 546 seconds in the first and second closures, respectively (P = .66), whereby the median leak rate improved from 14 to 7 (P = .34). There were also demonstrative technical improvements by all. Simulated spinal dura mater repair appears to be a potentially valuable tool in the education of neurosurgery residents. The combination of a didactic and technical assessment appears to be synergistic in terms of educational development.

Area Monitoring for Detection of Leaks and/or Flames

NASA Technical Reports Server (NTRS)

Mian, Zahid F. (Inventor); Gamache, Ronald W. (Inventor); Glasser, Nick (Inventor)

2015-01-01

A solution for monitoring an area for the presence of a flame and/or a leak, such as from a pressurized fluid, is provided. An imaging device can be used that acquires image data based on electromagnetic radiation having wavelengths only corresponding to at least one region of the electromagnetic spectrum in which electromagnetic radiation from an ambient light source is less than the electromagnetic radiation emitted by at least one type of flame for which the presence within the area is being monitored. An acoustic device can be used that is configured to acquire acoustic data for the area and enhance acoustic signals in a range of frequencies corresponding to a leak of a pressurized fluid present in the area.

Area Monitoring for Detection of Leaks And/Or Flames

NASA Technical Reports Server (NTRS)

Mian, Zahid F. (Inventor); Gamache, Ronald W. (Inventor); Glasser, Nicholas (Inventor)

2017-01-01

A solution for monitoring an area for the presence of a flame and/or a leak, such as from a pressurized fluid, is provided. An imaging device can be used that acquires image data based on electromagnetic radiation having wavelengths only corresponding to at least one region of the electromagnetic spectrum in which electromagnetic radiation from an ambient light source is less than the electromagnetic radiation emitted by at least one type of flame for which the presence within the area is being monitored. An acoustic device can be used that is configured to acquire acoustic data for the area and enhance acoustic signals in a range of frequencies corresponding to a leak of a pressurized fluid present in the area.

The Demonstration of a Robotic External Leak Locator on the International Space Station

NASA Technical Reports Server (NTRS)

Naids, Adam; Rossetti, Dino; Bond, Tim; Johnson, Brien; Huang, Alvin; Deal, Alexandra; Fox, Katie; Heiser, Michael; Hartman, William; Mikatarian, Ronald

2017-01-01

The International Space Station (ISS) and all currently conceivable future manned spacecraft are susceptible to mission impacts due to fluid/gas leaks to the exterior environment. For example, there is a well-known risk of ammonia leaks from the ISS External Thermal Control System loops and currently no method to locate them. It was, therefore, critical to develop a method for detecting and locating leaks to preserve vehicle health. The Robotic External Leak Locator (RELL) was developed and deployed to the ISS to provide this capability. An on-orbit validation and demonstration was successfully completed in December 2016 and leak locating operations occurred in February 2017. This paper discusses the results of those exercises including measurements of the environment around ISS, detection of the small ammonia leak and implementation of leak locating methodologies.

Extensive traumatic anterior skull base fractures with cerebrospinal fluid leak: classification and repair techniques using combined vascularized tissue flaps.

PubMed

Archer, Jacob B; Sun, Hai; Bonney, Phillip A; Zhao, Yan Daniel; Hiebert, Jared C; Sanclement, Jose A; Little, Andrew S; Sughrue, Michael E; Theodore, Nicholas; James, Jeffrey; Safavi-Abbasi, Sam

2016-03-01

This article introduces a classification scheme for extensive traumatic anterior skull base fracture to help stratify surgical treatment options. The authors describe their multilayer repair technique for cerebrospinal fluid (CSF) leak resulting from extensive anterior skull base fracture using a combination of laterally pediculated temporalis fascial-pericranial, nasoseptal-pericranial, and anterior pericranial flaps. Retrospective chart review identified patients treated surgically between January 2004 and May 2014 for anterior skull base fractures with CSF fistulas. All patients were treated with bifrontal craniotomy and received pedicled tissue flaps. Cases were classified according to the extent of fracture: Class I (frontal bone/sinus involvement only); Class II (extent of involvement to ethmoid cribriform plate); and Class III (extent of involvement to sphenoid bone/sinus). Surgical repair techniques were tailored to the types of fractures. Patients were assessed for CSF leak at follow-up. The Fisher exact test was applied to investigate whether the repair techniques were associated with persistent postoperative CSF leak. Forty-three patients were identified in this series. Thirty-seven (86%) were male. The patients' mean age was 33 years (range 11-79 years). The mean overall length of follow-up was 14 months (range 5-45 months). Six fractures were classified as Class I, 8 as Class II, and 29 as Class III. The anterior pericranial flap alone was used in 33 patients (77%). Multiple flaps were used in 10 patients (3 salvage) (28%)--1 with Class II and 9 with Class III fractures. Five (17%) of the 30 patients with Class II or III fractures who received only a single anterior pericranial flap had persistent CSF leak (p < 0.31). No CSF leak was found in patients who received multiple flaps. Although postoperative CSF leak occurred only in high-grade fractures with single anterior flap repair, this finding was not significant. Extensive anterior skull base

Leak detection in gas pipeline by acoustic and signal processing - A review

NASA Astrophysics Data System (ADS)

Adnan, N. F.; Ghazali, M. F.; Amin, M. M.; Hamat, A. M. A.

2015-12-01

The pipeline system is the most important part in media transport in order to deliver fluid to another station. The weak maintenance and poor safety will contribute to financial losses in term of fluid waste and environmental impacts. There are many classifications of techniques to make it easier to show their specific method and application. This paper's discussion about gas leak detection in pipeline system using acoustic method will be presented in this paper. The wave propagation in the pipeline is a key parameter in acoustic method when the leak occurs and the pressure balance of the pipe will generated by the friction between wall in the pipe. The signal processing is used to decompose the raw signal and show in time- frequency. Findings based on the acoustic method can be used for comparative study in the future. Acoustic signal and HHT is the best method to detect leak in gas pipelines. More experiments and simulation need to be carried out to get the fast result of leaking and estimation of their location.

MASS SPECTROMETER LEAK

DOEpatents

Shields, W.R.

1960-10-18

An improved valve is described for precisely regulating the flow of a sample fluid to be analyzed, such as in a mass spectrometer, where a gas sample is allowed to "leak" into an evacuated region at a very low, controlled rate. The flow regulating valve controls minute flow of gases by allowing the gas to diffuse between two mating surfaces. The structure of the valve is such as to prevent the corrosive feed gas from contacting the bellows which is employed in the operation of the valve, thus preventing deterioration of the bellows.

An approximate solution for a penny-shaped hydraulic fracture that accounts for fracture toughness, fluid viscosity and leak-off.

PubMed

Dontsov, E V

2016-12-01

This paper develops a closed-form approximate solution for a penny-shaped hydraulic fracture whose behaviour is determined by an interplay of three competing physical processes that are associated with fluid viscosity, fracture toughness and fluid leak-off. The primary assumption that permits one to construct the solution is that the fracture behaviour is mainly determined by the three-process multiscale tip asymptotics and the global fluid volume balance. First, the developed approximation is compared with the existing solutions for all limiting regimes of propagation. Then, a solution map, which indicates applicability regions of the limiting solutions, is constructed. It is also shown that the constructed approximation accurately captures the scaling that is associated with the transition from any one limiting solution to another. The developed approximation is tested against a reference numerical solution, showing that accuracy of the fracture width and radius predictions lie within a fraction of a per cent for a wide range of parameters. As a result, the constructed approximation provides a rapid solution for a penny-shaped hydraulic fracture, which can be used for quick fracture design calculations or as a reference solution to evaluate accuracy of various hydraulic fracture simulators.

An approximate solution for a penny-shaped hydraulic fracture that accounts for fracture toughness, fluid viscosity and leak-off

NASA Astrophysics Data System (ADS)

Dontsov, E. V.

2016-12-01

This paper develops a closed-form approximate solution for a penny-shaped hydraulic fracture whose behaviour is determined by an interplay of three competing physical processes that are associated with fluid viscosity, fracture toughness and fluid leak-off. The primary assumption that permits one to construct the solution is that the fracture behaviour is mainly determined by the three-process multiscale tip asymptotics and the global fluid volume balance. First, the developed approximation is compared with the existing solutions for all limiting regimes of propagation. Then, a solution map, which indicates applicability regions of the limiting solutions, is constructed. It is also shown that the constructed approximation accurately captures the scaling that is associated with the transition from any one limiting solution to another. The developed approximation is tested against a reference numerical solution, showing that accuracy of the fracture width and radius predictions lie within a fraction of a per cent for a wide range of parameters. As a result, the constructed approximation provides a rapid solution for a penny-shaped hydraulic fracture, which can be used for quick fracture design calculations or as a reference solution to evaluate accuracy of various hydraulic fracture simulators.

Fluid sampling device

NASA Technical Reports Server (NTRS)

Studenick, D. K. (Inventor)

1977-01-01

An inlet leak is described for sampling gases, more specifically, for selectively sampling multiple fluids. This fluid sampling device includes a support frame. A plurality of fluid inlet devices extend through the support frame and each of the fluid inlet devices include a longitudinal aperture. An opening device that is responsive to a control signal selectively opens the aperture to allow fluid passage. A closing device that is responsive to another control signal selectively closes the aperture for terminating further fluid flow.

Modeling the GPR response of leaking, buried pipes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powers, M.H.; Olhoeft, G.R.

1996-11-01

Using a 2.5D, dispersive, full waveform GPR modeling program that generates complete GPR response profiles in minutes on a Pentium PC, the effects of leaking versus non-leaking buried pipes are examined. The program accounts for the dispersive, lossy nature of subsurface materials to GPR wave propagation, and accepts complex functions of dielectric permittivity and magnetic permeability versus frequency through Cole-Cole parameters fit to laboratory data. Steel and plastic pipes containing a DNAPL chlorinated solvent, an LNAPL hydrocarbon, and natural gas are modeled in a surrounding medium of wet, moist, and dry sand. Leaking fluids are found to be more detectablemore » when the sand around the pipes is fully water saturated. The short runtimes of the modeling program and its execution on a PC make it a useful tool for exploring various subsurface models.« less

A Hydrazine Leak Sensor Based on Chemically Reactive Thermistors

NASA Technical Reports Server (NTRS)

Davis, Dennis D.; Mast, Dion J.; Baker, David L.

1999-01-01

Leaks in the hydrazine supply system of the Shuttle APU can result in hydrazine ignition and fire in the aft compartment of the Shuttle. Indication of the location of a leak could provide valuable information required for operational decisions. WSTF has developed a small, single use sensor for detection of hydrazine leaks. The sensor is composed of a thermistor bead coated with copper(II) oxide (CuO) dispersed in a clay or alumina binder. The CuO-coated thermistor is one of a pair of closely located thermistors, the other being a reference. On exposure to hydrazine the CuO reacts exothermically with the hydrazine and increases the temperature of the coated-thermistor by several degrees. The temperature rise is sensed by a resistive bridge circuit and an alarm registered by data acquisition software. Responses of this sensor to humidity changes, hydrazine concentration, binder characteristics, distance from a liquid leak, and ambient pressure levels as well as application of this sensor concept to other fluids are presented.

40 CFR 63.1331 - Equipment leak provisions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... in pumps and agitator seals in light liquid service shall not be considered to be a leak. For purposes of this subpart, a “bleed port” is a technologically-required feature of the pump or seal whereby polymer fluid used to provide lubrication and/or cooling of the pump or agitator shaft exits the pump...

Risk Factors for Gastrointestinal Leak after Bariatric Surgery: MBASQIP Analysis.

PubMed

Alizadeh, Reza Fazl; Li, Shiri; Inaba, Colette; Penalosa, Patrick; Hinojosa, Marcelo W; Smith, Brian R; Stamos, Michael J; Nguyen, Ninh T

2018-03-30

Gastrointestinal leak remains one of the most dreaded complications in bariatric surgery. We aimed to evaluate risk factors and the impact of common perioperative interventions on the development of leak in patients who underwent laparoscopic bariatric surgery. Using the 2015 database of accredited centers, data were analyzed for patients who underwent laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass (LRYGB). Emergent, revisional, and converted cases were excluded. Multivariate logistic regression was used to analyze risk factors for leak, including provocative testing of anastomosis, surgical drain placement, and use of postoperative swallow study. Data from 133,478 patients who underwent laparoscopic sleeve gastrectomy (n = 92,495 [69.3%]) and LRYGB (n = 40,983 [30.7%]) were analyzed. Overall leak rate was 0.7% (938 of 133,478). Factors associated with increased risk for leak were oxygen dependency (adjusted odds ratio [AOR] 1.97), hypoalbuminemia (AOR 1.66), sleep apnea (AOR 1.52), hypertension (AOR 1.36), and diabetes (AOR 1.18). Compared with LRYGB, laparoscopic sleeve gastrectomy was associated with a lower risk of leak (AOR 0.52; 95% CI 0.44 to 0.61; p < 0.01). Intraoperative provocative test was performed in 81.9% of cases and the leak rate was higher in patients with vs without a provocative test (0.8% vs 0.4%, respectively; p < 0.01). A surgical drain was placed in 24.5% of cases and the leak rate was higher in patients with vs without a surgical drain placed (1.6% vs 0.4%, respectively; p < 0.01). A swallow study was performed in 41% of cases and the leak rate was similar between patients with vs without swallow study (0.7% vs 0.7%; p = 0.50). The overall rate of gastrointestinal leak in bariatric surgery is low. Certain preoperative factors, procedural type (LRYGB), and interventions (intraoperative provocative test and surgical drain placement) were associated with a higher risk for leaks. Copyright © 2018 American College of Surgeons

Reconstruction after retrosigmoid approaches using autologous fat graft-assisted Medpor Titan cranioplasty: assessment of postoperative cerebrospinal fluid leaks and headaches in 60 cases.

PubMed

Ling, Phoebe Y; Mendelson, Zachary S; Reddy, Rohit K; Jyung, Robert W; Liu, James K

2014-10-01

Postoperative cerebrospinal fluid (CSF) leaks and headaches remain potential complications after retrosigmoid approaches for lesions in the posterior fossa and cerebellopontine angle. The authors describe a simple repair technique with an autologous fat graft-assisted Medpor Titan cranioplasty and investigate the incidence of postoperative CSF leaks and headaches using this technique. A retrospective chart review was conducted on all cases (n = 60) of retrosigmoid craniectomy from September 2009 to May 2014 in patients who underwent fat graft-assisted cranioplasty. After obtaining a watertight dural closure and sealing off any visible mastoid air cells with bone wax, an autologous fat graft was placed over the dural suture line and up against the waxed-off air cells. The fat graft filled the retrosigmoid cranial defect and was then bolstered with a Medpor Titan (titanium mesh embedded in porous polyethylene) cranioplasty. A postoperative mastoid pressure dressing was applied for 48 h, and prophylactic lumbar drainage was not used. Factors examined in this study included postoperative CSF leak (incisional, rhinorrhea, otorrhea), pseudomeningocele formation, incidence and severity of postoperative headache, length of hospital stay, and length of follow-up. No patients developed postoperative CSF leaks (0 %), pseudomeningoceles (0 %), or new-onset postoperative headaches (0 %) with the described repair technique. There were no cases of graft site morbidity such as hematoma or wound infection. Mean duration of postoperative hospital stay was 3.8 days (range 2-10 days). Mean postoperative follow-up was 12.4 months (range 2.0-41.1 months). Our multilayer repair technique with a fat graft-assisted Medpor Titan cranioplasty appears effective in preventing postoperative CSF leaks and new-onset postoperative headaches after retrosigmoid approaches. Postoperative lumbar drainage may not be necessary.

Water Pipeline Monitoring and Leak Detection using Flow Liquid Meter Sensor

NASA Astrophysics Data System (ADS)

Rahmat, R. F.; Satria, I. S.; Siregar, B.; Budiarto, R.

2017-04-01

Water distribution is generally installed through underground pipes. Monitoring the underground water pipelines is more difficult than monitoring the water pipelines located on the ground in open space. This situation will cause a permanent loss if there is a disturbance in the pipeline such as leakage. Leaks in pipes can be caused by several factors, such as the pipe’s age, improper installation, and natural disasters. Therefore, a solution is required to detect and to determine the location of the damage when there is a leak. The detection of the leak location will use fluid mechanics and kinematics physics based on harness water flow rate data obtained using flow liquid meter sensor and Arduino UNO as a microcontroller. The results show that the proposed method is able to work stably to determine the location of the leak which has a maximum distance of 2 metres, and it’s able to determine the leak location as close as possible with flow rate about 10 litters per minute.

Normally-Closed Zero-Leak Valve with Magnetostrictive Actuator

NASA Technical Reports Server (NTRS)

Ramspacher, Daniel J. (Inventor); Richard, James A. (Inventor)

2017-01-01

A non-pyrotechnic, normally-closed, zero-leak valve is a replacement for the pyrovalve used for both in-space and launch vehicle applications. The valve utilizes a magnetostrictive alloy for actuation, rather than pyrotechnic charges. The alloy, such as Terfenol-D, experiences magnetostriction, i.e. a gross elongation, when exposed to a magnetic field. This elongation fractures a parent metal seal, allowing fluid flow through the valve. The required magnetic field is generated by redundant coils that are isolated from the working fluid.

The utility of CT for predicting bile leaks in hepatic trauma.

PubMed

LeBedis, Christina A; Anderson, Stephan W; Mercier, Gustavo; Kussman, Steven; Coleman, Stephanie L; Golden, Louis; Penn, David R; Uyeda, Jennifer W; Soto, Jorge A

2015-04-01

The purpose of this study was to determine the efficacy of CT to predict the development of bile leaks in hepatic trauma. This HIPAA-compliant retrospective study was IRB approved and consent was waived. All patients who sustained hepatic trauma between January 1, 2006, and January 31, 2012, and who underwent CT and hepatobiliary scans during the same hospital admission were included. One hundred and thirty-two patients met the inclusion criteria. Comparison between the presence of biliary injury relative to American Association for the Surgery of Trauma (AAST) hepatic injury grade and mean distance of the hepatic laceration to the inferior vena cava (IVC) was made. The ability of free fluid to predict bile injury was analyzed. Forty-one (31 %) of the 132 patients had positive hepatobiliary scans. Of these 41 patients, seven (17 %) sustained low-grade and 34 (83 %) sustained high-grade hepatic injury compared with the 37 (41 %) low-grade and 54 (59 %) high-grade hepatic injuries in the negative hepatobiliary scan group. The mean distance to the IVC was 2.4 cm (SD 2.9 cm) and 3.6 cm (SD 3.3 cm) in patients with and without bile leaks, respectively. A statistically significant difference in the proportion of high-grade injuries and the mean distance from the IVC between the two groups was identified. The presence of free fluid on CT is sensitive, but not specific, for detecting a bile leak. CT findings, including AAST liver injury grade and location of the liver laceration, are able to predict which patients are at risk for developing bile leaks as seen on hepatobiliary scintigraphy, whereas the presence of free fluid is not.

Development of a leak location system for use on underground electric power transmission cable

NASA Astrophysics Data System (ADS)

Williams, J. A.

1982-10-01

This report describes a study to evaluate methods for locating leaks of dielectric fluid from buried high voltage cable systems. Two primary types of leak location systems were investigated: (1) systems that will rapidly isolate the leak within a manhole section, typically 1000 m long on a feeder that might be 30 km long; and (2) systems that will then pinpoint the location of the leak. Rapid leak isolation was accomplished by developing an enhanced conductivity oil probe which allows the injection of a small quantity of conductive oil and which indicates the path of the oil as it drifts downstream in the direction of the leak. Two methods for pinpointing the leak were proven. The more successful method was the use of trained leak location dogs which were found to have far better sensitivity than instruments and which could detect cable oil alone without the need for additives. A tracer gas injection and detection scheme was developed for use in areas where the dogs may be unsuitable.

Temperature and Atomic Oxygen Effects on Helium Leak Rates of a Candidate Main Interface Seal

NASA Technical Reports Server (NTRS)

Penney, Nicholas; Wasowski, Janice L.; Daniels, Christopher C.

2011-01-01

Helium leak tests were completed to characterize the leak rate of a 54 in. diameter composite space docking seal design in support of the National Aeronautics and Space Administration s (NASA's) Low Impact Docking System (LIDS). The evaluated seal design was a candidate for the main interface seal on the LIDS, which would be compressed between two vehicles, while docked, to prevent the escape of breathable air from the vehicles and into the vacuum of space. Leak tests completed at nominal temperatures of -30, 20, and 50 C on untreated and atomic oxygen (AO) exposed test samples were examined to determine the influence of both test temperature and AO exposure on the performance of the composite seal assembly. Results obtained for untreated seal samples showed leak rates which increased with increased test temperature. This general trend was not observed in tests of the AO exposed specimens. Initial examination of collected test data suggested that AO exposure resulted in higher helium leak rates, however, further analysis showed that the differences observed in the 20 and 50 C tests between the untreated and AO exposed samples were within the experimental error of the test method. Lack of discernable trends in the test data prevented concrete conclusions about the effects of test temperature and AO exposure on helium leak rates of the candidate seal design from being drawn. To facilitate a comparison of the current test data with results from previous leak tests using air as the test fluid, helium leak rates were converted to air leak rates using standard conversion factors for viscous and molecular flow. Flow rates calculated using the viscous flow conversion factor were significantly higher than the experimental air leakage values, whereas values calculated using the molecular flow conversion factor were significantly lower than the experimentally obtained air leak rates. The difference in these sets of converted flow rates and their deviation from the

The potential for spills and leaks of hydraulic fracturing related fluids on well sites and from road incidents.

NASA Astrophysics Data System (ADS)

Clancy, Sarah; Worrall, Fred; Davies, Richard; Gluyas, Jon

2017-04-01

The potential growth of shale gas developments within Europe has raised concerns of the possibility of spills and leaks from shale gas sites and from liquid transportation via roads and pipelines. Data from a range of sources has been examined to estimate the likelihood of an incident. From the US, the Texas Railroad Commission and the Colorado Oil and Gas Commission have maintained records of the quantity; reasons for the spill; and reported impacts. For the UK, the Environment Agency pollution incident database and transport statistics from the UKs Department for Transport have also been analysed and used as an analogy to determine the likelihood of an incident or spill on the road. Data were used as an analogue to predict the potential number of spills and leaks that might occur at a well site, or in transport operation, under different shale gas development scenarios if fracking was to go forward in the UK. Since 2014 the Colorado Oil and Gas Commission has recorded 3874 spills in the State of Colorado, the majority of these (1941) consisted of produced water, whereas 835 recorded oil spills. Of all the spills recorded 1809 spilt more than 0.79 m3, with 1356 of these leaking outside the berm of the well site, and three sites requiring construction of an emergency pits to contain the spillage. During 2015, there were 53054 active wells; the percentage of produced oil spilt was 0.001%, whilst the percentage of produced water spilt was 0.009%. Data from the Texas Railroad Commission shows the number of reported spills over 0.16 m3 in Texas since 2009 has increased year on year, with 675 reported in 2009 and 1485 in 2015. The greatest loss each year was of crude oil, with 14176 m3 being spilt in 2015, which is equivalent to 0.0089% of the oil produced. Clean-up operations recover some of the lost fluid; however, much is left unrecovered, annually 60% of the crude oil spilt is recovered, 65% of production fluid is recovered, whereas just 30% of liquid gas is

Single-Shell Tanks Leak Integrity Elements/ SX Farm Leak Causes and Locations - 12127

DOE Office of Scientific and Technical Information (OSTI.GOV)

Girardot, Crystal; Harlow, Don; Venetz, Theodore

2012-07-01

related to leak detection. In-tank parameters can include temperature of the supernatant and sludge, types of waste, and chemical determination by either transfer or sample analysis. Ex-tank information can be assembled from many sources including design media, construction conditions, technical specifications, and other sources. Five conditions may have contributed to SX Farm tank liner failure including: tank design, thermal shock, chemistry-corrosion, liner behavior (bulging), and construction temperature. Tank design did not apparently change from tank to tank for the SX Farm tanks; however, there could be many unknown variables present in the quality of materials and quality of construction. Several significant SX Farm tank design changes occurred from previous successful tank farm designs. Tank construction occurred in winter under cold conditions which could have affected the ductile to brittle transition temperature of the tanks. The SX Farm tanks received high temperature boiling waste from REDOX which challenged the tank design with rapid heat up and high temperatures. All eight of the leaking SX Farm tanks had relatively high rate of temperature rise. Supernatant removal with subsequent nitrate leaching was conducted in all but three of the eight leaking tanks prior to leaks being detected. It is possible that no one characteristic of the SX Farm tanks could in isolation from the others have resulted in failure. However, the application of so many stressors - heat up rate, high temperature, loss of corrosion protection, and tank design working jointly or serially resulted in their failure. Thermal shock coupled with the tank design, construction conditions, and nitrate leaching seem to be the overriding factors that can lead to tank liner failure. The distinction between leaking and sound SX Farm tanks seems to center on the waste types, thermal conditions, and nitrate leaching. (authors)« less

SINGLE-SHELL TANKS LEAK INTEGRITY ELEMENTS/SX FARM LEAK CAUSES AND LOCATIONS - 12127

DOE Office of Scientific and Technical Information (OSTI.GOV)

VENETZ TJ; WASHENFELDER D; JOHNSON J

2012-01-25

related to leak detection. In-tank parameters can include temperature of the supernatant and sludge, types of waste, and chemical determination by either transfer or sample analysis. Ex-tank information can be assembled from many sources including design media, construction conditions, technical specifications, and other sources. Five conditions may have contributed to SX Farm tank liner failure including: tank design, thermal shock, chemistry-corrosion, liner behavior (bulging), and construction temperature. Tank design did not apparently change from tank to tank for the SX Farm tanks; however, there could be many unknown variables present in the quality of materials and quality of construction. Several significant SX Farm tank design changes occurred from previous successful tank farm designs. Tank construction occurred in winter under cold conditions which could have affected the ductile to brittle transition temperature of the tanks. The SX Farm tanks received high temperature boiling waste from REDOX which challenged the tank design with rapid heat up and high temperatures. All eight of the leaking SX Farm tanks had relatively high rate of temperature rise. Supernatant removal with subsequent nitrate leaching was conducted in all but three of the eight leaking tanks prior to leaks being detected. It is possible that no one characteristic of the SX Farm tanks could in isolation from the others have resulted in failure. However, the application of so many stressors - heat up rate, high temperature, loss of corrosion protection, and tank design - working jointly or serially resulted in their failure. Thermal shock coupled with the tank design, construction conditions, and nitrate leaching seem to be the overriding factors that can lead to tank liner failure. The distinction between leaking and sound SX Farm tanks seems to center on the waste types, thermal conditions, and nitrate leaching.« less

Identification of sewage leaks by active remote-sensing methods

NASA Astrophysics Data System (ADS)

Goldshleger, Naftaly; Basson, Uri

2016-04-01

The increasing length of sewage pipelines, and concomitant risk of leaks due to urban and industrial growth and development is exposing the surrounding land to contamination risk and environmental harm. It is therefore important to locate such leaks in a timely manner, to minimize the damage. Advances in active remote sensing Ground Penetrating Radar (GPR) and Frequency Domain Electromagnetic (FDEM) technologies was used to identify leaking potentially responsible for pollution and to identify minor spills before they cause widespread damage. This study focused on the development of these electromagnetic methods to replace conventional acoustic methods for the identification of leaks along sewage pipes. Electromagnetic methods provide an additional advantage in that they allow mapping of the fluid-transport system in the subsurface. Leak-detection systems using GPR and FDEM are not limited to large amounts of water, but enable detecting leaks of tens of liters per hour, because they can locate increases in environmental moisture content of only a few percentage along the pipes. The importance and uniqueness of this research lies in the development of practical tools to provide a snapshot and monitoring of the spatial changes in soil moisture content up to depths of about 3-4 m, in open and paved areas, at relatively low cost, in real time or close to real time. Spatial measurements performed using GPR and FDEM systems allow monitoring many tens of thousands of measurement points per hectare, thus providing a picture of the spatial situation along pipelines and the surrounding. The main purpose of this study was to develop a method for detecting sewage leaks using the above-proposed geophysical methods, since their contaminants can severely affect public health. We focused on identifying, locating and characterizing such leaks in sewage pipes in residential and industrial areas.

White gauze test: a novel technique in preventing post-hepatectomy bile leak.

PubMed

Yugasaravanan, K; Affirul, C A; Zamri, Z; Azlanudin, A; Bong, J J

Post-hepatectomy bile leak may lead to undesired morbidity. Multiple methods have been employed to identify this leak but can be inconclusive and taxing. This novel white gauze test is a simple and reliable method. This is a prospective study performed from January 2010 until March 2011. All open hepatic resection were included. Dry white gauze is compressed onto the transected surface and observed for bile staining. The leaking duct is repaired immediately upon detection. The process is repeated until negative. Drain was removed on postoperative day-5. Post-operative bile leak is defined as: 1. Bilirubin concentration of the drain fluid is 3 times or higher than serum; 2. Presence of intra-abdominal bile collection on imaging and upon drainage; 3. Bile leak demonstrated on postoperative cholangiography. 42 patients were recruited. Seven (16.7%) patients were cirrhotic with Child-Pugh A. White gauze test were positive for intra-operative bile leaks in 29 patients (70%), which were primarily repaired. As a result, there was no postoperative bile leak in this series. One mortality was detected in this series due to postoperative pancreatic fistula and multi organ failure. The White Gauze Test is a useful method for the prevention of bile leakage after hepatic resection. It is safe, quick and cheap.

Fiber optic distributed chemical sensor for the real time detection of hydrocarbon fuel leaks

NASA Astrophysics Data System (ADS)

Mendoza, Edgar; Kempen, C.; Esterkin, Yan; Sun, Sunjian

2015-09-01

With the increase worldwide demand for hydrocarbon fuels and the vast development of new fuel production and delivery infrastructure installations around the world, there is a growing need for reliable hydrocarbon fuel leak detection technologies to provide safety and reduce environmental risks. Hydrocarbon leaks (gas or liquid) pose an extreme danger and need to be detected very quickly to avoid potential disasters. Gas leaks have the greatest potential for causing damage due to the explosion risk from the dispersion of gas clouds. This paper describes progress towards the development of a fast response, high sensitivity, distributed fiber optic fuel leak detection (HySense™) system based on the use of an optical fiber that uses a hydrocarbon sensitive fluorescent coating to detect the presence of fuel leaks present in close proximity along the length of the sensor fiber. The HySense™ system operates in two modes, leak detection and leak localization, and will trigger an alarm within seconds of exposure contact. The fast and accurate response of the sensor provides reliable fluid leak detection for pipelines, storage tanks, airports, pumps, and valves to detect and minimize any potential catastrophic damage.

Anastomotic leaks in stage IV colorectal cancer.

PubMed

Ng, Suat Chin; Stupart, Douglas; Bartolo, David; Watters, David

2018-06-12

The purpose of this study was to determine the anastomotic leak rate for colorectal cancer resections in patients with metastases (compared to those without), and to determine the impact of anastomotic leaks on survival. This is a retrospective analysis of all patients who underwent resection and primary anastomosis for colorectal adenocarcinoma at a single institution between January 2002 and December 2014. A total of 843 patients underwent a resection and primary anastomosis for colorectal adenocarcinoma (661 colon and 182 rectal). Of these, 135 (16%) had metastases and 708 (84%) did not. Anastomotic leaks occurred in 17 of 135 (13%) patients with metastases, and in 37 of 798 (5.2%) patients without metastases (P = 0.003). Peri-operative mortality occurred in 13 of 135 (9.6%) patients with metastases, compared with 19 of 708 (2.7%) patients without metastases (P = 0.0003). Anastomotic leak was associated with a reduction in overall survival (median survival 121 months without anastomotic leak versus 66 months in patients who had an anastomotic leak (P = 0.02)). If the patients who died peri-operatively are excluded from this analysis, however, long-term mortality was similar (125 months versus 101 months; P = 0.70). Metastatic disease was associated with an increased risk of anastomotic leak and a higher peri-operative mortality rate after colorectal resections for cancer. Patients with anastomotic leaks had a higher peri-operative mortality rate, but long-term survival was unaffected beyond the peri-operative phase. © 2018 Royal Australasian College of Surgeons.

Anastomotic leaks: what is the best diagnostic imaging study?

PubMed

Nicksa, G A; Dring, R V; Johnson, K H; Sardella, W V; Vignati, P V; Cohen, J L

2007-02-01

Postoperative anastomotic leaks are one of the most devastating consequences of colorectal surgery. Diagnostic imaging for upper gastrointestinal anastomotic leaks has been evaluated and reported on extensively. No study has compared the utility and effectiveness of CT scans and water-soluble enemas for the identification of postoperative lower gastrointestinal anastomotic leaks. The present study was designed to evaluate and compare these two common radiographic imaging modalities in detecting lower gastrointestinal anastomotic leaks. A retrospective chart review was performed that identified 36 patients during a seven-year period who underwent reoperative surgery for a lower gastrointestinal anastomotic leak. Patient's imaging studies were classified as positive if extravasation of contrast material was demonstrated. When negative, a study was retrospectively reviewed in an attempt to identify findings suggestive of an anastomotic leak. There were 36 patients identified with a postoperative lower gastrointestinal leak requiring surgical intervention. There were 28 of 36 patients (78 percent) re-explored on the basis of a radiologic study demonstrating an anastomotic leak. A total of 27 CT scans were performed, of which 4 (14.8 percent) were considered positive for an anastomotic leak. On review of the remaining negative CT scans, nine (33.3 percent) were considered descriptive positive with a large amount of fluid or air in the peritoneal cavity but without obvious extravasation of contrast. Eighteen patients were evaluated with a water-soluble enema and 15 (83.3 percent) demonstrated extravasation of contrast material. In the 26 patients with a distal anastomotic leak, 17 water-soluble enemas were performed, with 15 (88 percent) demonstrating a leak. In contrast, only 2 of 17 (12 percent) CT scans were positive in this group of patients (P < 0.001). There were ten patients who initially had a CT scan followed by a water-soluble enema. Of these patients, eight of

Cerebrospinal fluid rhinorrhea following trans-sphenoidal pituitary macroadenoma surgery: experience from 592 patients.

PubMed

Han, Zong-Li; He, Dong-Sheng; Mao, Zhi-Gang; Wang, Hai-Jun

2008-06-01

To determine the incidence, risk factors, diagnostic procedures, and management of cerebrospinal fluid (CSF) leaks following trans-sphenoidal pituitary macroadenoma surgery. Retrospective analysis of 592 patients. Intra- and post-operative CSF leaks occurred in 14.2 and 4.4% of patients, respectively. Surgical revision, tumor consistency, and tumor margins were independently associated with intra-operative leaks, while the tumor size, consistency, and margins were risk factors of post-operative leaks. The intra-operative leak rate of ACTH adenomas was greater than all other types combined; the incidence of post-operative CSF leaks was highest for FSH adenomas. There were no significant differences among various techniques and we achieved an initial repair success rates of 83.3 and 92.9% for intra- and post-operative CSF leaks, respectively. Of the 26 patients with post-operative CSF leaks, five were complicated by meningitis and four by post-infectious hydrocephalus which required ventriculoperitoneal shunts. CSF leaks have a propensity to occur in cases with fibrous tumors or tumors with indistinct margin and may have some relationship with the tumor type. Endoscopic and microscopic repairs were shown to be effective techniques in managing these types of leaks. Post-infectious hydrocephalus may influence the outcome of the repair and ventriculoperitoneal shunts were necessary in some cases.

Human body fluid proteome analysis

PubMed Central

Hu, Shen; Loo, Joseph A.; Wong, David T.

2010-01-01

The focus of this article is to review the recent advances in proteome analysis of human body fluids, including plasma/serum, urine, cerebrospinal fluid, saliva, bronchoalveolar lavage fluid, synovial fluid, nipple aspirate fluid, tear fluid, and amniotic fluid, as well as its applications to human disease biomarker discovery. We aim to summarize the proteomics technologies currently used for global identification and quantification of body fluid proteins, and elaborate the putative biomarkers discovered for a variety of human diseases through human body fluid proteome (HBFP) analysis. Some critical concerns and perspectives in this emerging field are also discussed. With the advances made in proteomics technologies, the impact of HBFP analysis in the search for clinically relevant disease biomarkers would be realized in the future. PMID:17083142

Human body fluid proteome analysis.

PubMed

Hu, Shen; Loo, Joseph A; Wong, David T

2006-12-01

The focus of this article is to review the recent advances in proteome analysis of human body fluids, including plasma/serum, urine, cerebrospinal fluid, saliva, bronchoalveolar lavage fluid, synovial fluid, nipple aspirate fluid, tear fluid, and amniotic fluid, as well as its applications to human disease biomarker discovery. We aim to summarize the proteomics technologies currently used for global identification and quantification of body fluid proteins, and elaborate the putative biomarkers discovered for a variety of human diseases through human body fluid proteome (HBFP) analysis. Some critical concerns and perspectives in this emerging field are also discussed. With the advances made in proteomics technologies, the impact of HBFP analysis in the search for clinically relevant disease biomarkers would be realized in the future.

Ultrafast dynamic computed tomography myelography for the precise identification of high-flow cerebrospinal fluid leaks caused by spiculated spinal osteophytes.

PubMed

Thielen, Kent R; Sillery, John C; Morris, Jonathan M; Hoxworth, Joseph M; Diehn, Felix E; Wald, John T; Rosebrock, Richard E; Yu, Lifeng; Luetmer, Patrick H

2015-03-01

Precise localization and understanding of the origin of spontaneous high-flow spinal CSF leaks is required prior to targeted treatment. This study demonstrates the utility of ultrafast dynamic CT myelography for the precise localization of high-flow CSF leaks caused by spiculated spinal osteophytes. This study reports a series of 14 patients with high-flow CSF leaks caused by spiculated spinal osteophytes who underwent ultrafast dynamic CT myelography between March 2009 and December 2010. There were 10 male and 4 female patients, with an average age of 49 years (range 37-74 years). The value of ultrafast dynamic CT myelography in depicting the CSF leak site was qualitatively assessed. In all 14 patients, ultrafast dynamic CT myelography was technically successful at precisely demonstrating the site of the CSF leak, the causative spiculated osteophyte piercing the dura, and the relationship of the implicated osteophyte to adjacent structures. Leak sites included 3 cervical, 11 thoracic, and 0 lumbar levels, with 86% of the leaks occurring from C-5 to T-7. Information obtained from the ultrafast dynamic CT myelogram was considered useful in all treated CSF leaks. Spinal osteophytes piercing the dura are a more frequent cause of high-flow CSF leaks than previously recognized. Ultrafast dynamic CT myelography adds value beyond standard dynamic myelography or digital subtraction myelography in the diagnosis and anatomical characterization of high-flow spinal CSF leaks caused by these osteophytes. This information allows for appropriate planning for percutaneous or surgical treatment.

Recognition and management of idiopathic systemic capillary leak syndrome: an evidence-based review.

PubMed

Baloch, Noor Ul-Ain; Bikak, Marvi; Rehman, Abdul; Rahman, Omar

2018-05-01

Idiopathic systemic capillary leak syndrome (SCLS) is a unique disorder characterized by episodes of massive systemic leak of intravascular fluid leading to volume depletion and shock. A typical attack of SCLS consists of prodromal, leak and post-leak phases. Complications, such as compartment syndrome and pulmonary edema, usually develop during the leak and post-leak phases respectively. Judicious intravenous hydration and early use of vasopressors is the cornerstone of management in such cases. Areas covered: The purpose of the present review is to provide an up-to-date, evidence-based review of our understanding of SCLS and its management in the light of currently available evidence. Idiopathic SCLS was first described in 1960 and, since then, more than 250 cases have been reported. A large number of cases have been reported over the past one decade, most likely due to improved recognition. In the acute care setting, most patients with SCLS are managed as per the Surviving Sepsis guidelines and receive aggressive volume resuscitation - which is not the optimal management strategy for such patients. There is a need to raise awareness amongst physicians and clinicians in order to improve recognition of this disorder and ensure its appropriate management.

High serum lactate as an adjunct in the early prediction of anastomotic leak following oesophagectomy.

PubMed

Ip, B; Ng, K T; Packer, S; Paterson-Brown, S; Couper, G W

2017-10-01

Anastomotic leak (AL) following oesophagectomy carries a high mortality and morbidity. Early detection and intervention is required for a successful outcome. We have examined the role of a high postoperative serum lactate in predicting which patients are at risk of developing an anastomotic leak(AL). All patients who underwent transthoracic oesophagectomy over a 3-year period were identified from a prospectively collected database. Medical records were reviewed to identify the highest serum lactate recorded from blood gas analysis over each 24hr post-operative period. Patients who underwent transhiatal and left thoraco-abdominal oesophagectomies were excluded. Patients who developed a chyle leak were excluded. Of a total of 136 oesophagectomies included for analysis, 18 developed an AL (13.2%). Of these patients, 10 underwent thoracoscopic oesophageal mobilization with cervical anastomosis and the rest an Ivor Lewis procedure. Predictive factors for AL included neoadjuvant chemotherapy (15/18 83.3% vs 55/118 46.6% p = 0.0046) and number of positive lymph nodes (mean 4.2 vs control mean 2.3 p = 0.045). Overall net fluid balance was comparable between the 2 groups, although AL patients received slightly more fluid on Day 3. High lactate levels on days 1-3 were associated with an AL. Using a Day 2 lactate of 1.7 mmol/L, the sensitivity of predicting AL was 72% and specificity 88%. The mean lag time using existing diagnostic modalities was 7.9 days. A serum lactate of >1.7 mmol/l on day 2 should raise the possibility of a potential AL. Such patients should be selected for more intensive monitoring, optimization and selective gastroscopy. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Space Shuttle RCS Oxidizer Leak Repair for STS-26

NASA Technical Reports Server (NTRS)

Delventhal, R. A.; Faget, N. M.

1989-01-01

Following propellant loading of the Space Shuttle's reaction control system (RCS) for mission STS 26, an oxidizer leak was detected in the left orbital maneuvering system (OMS) pod, where the RCS is located. Subsequent investigation determined that the leak was isolated at a mechanical Dynatube fitting near the RCS nitrogen tetroxide tank. An intense effort was initiated to design, fabricate, and qualify a sealing device to stop the oxidizer leak externally so that the Space Shuttle launch could proceed. It was discovered that sealing devices called clamshells were widely used throughout the petrochemical and power generation industries to stop leaks developed in large diameter pipes which carry steam or other hazardous fluids. These clamshells are available in different diameters and strengths and are placed around the pipe at the location of the leak. A sealing compound is then injected under high pressure into the clamshell to stop the leak. This technology was scaled down and applied to the problem of stopping the leak on the Orbiter, which was on a half-inch diameter line in a nearly inaccessible location. Many obstacles had to be overcome such as determining that the sealing material would be compatible with the nitrogen tetroxide and ensuring that the clamshell would actually fit around the Dynatube fitting without interfering with other lines which were in close proximity. The effort at the NASA Johnson Space Center included materials compatibility testing of several sealants, design of a clamshell to fit in the confined compartment, and manufacture and qualification of the flight hardware. A clamshell was successfully placed around the Dynatube fitting on the Orbiter and the oxidizer leak was terminated. Then it was decided to apply this technology further and design clamshells for other mechanical fittings onboard the Orbiter and develop sealing compounds which will be compatible with fuels such as monomethyl hydrazine (MMH). The potential exists for

Individual surgeon is an independent risk factor for leak after double-stapled colorectal anastomosis: An institutional analysis of 800 patients.

PubMed

García-Granero, Eduardo; Navarro, Francisco; Cerdán Santacruz, Carlos; Frasson, Matteo; García-Granero, Alvaro; Marinello, Franco; Flor-Lorente, Blas; Espí, Alejandro

2017-11-01

Our aim was to assess whether the individual surgeon is an independent risk factor for anastomotic leak in double-stapled colorectal anastomosis after left colon and rectal cancer resection. This retrospective analysis of a prospectively collected database consists of a consecutive series of 800 patients who underwent an elective left colon and rectal resection with a colorectal, double-stapled anastomosis between 1993 and 2009 in a specialized colorectal unit of a tertiary hospital with 7 participating surgeons. The main outcome variable was anastomotic leak, defined as leak of luminal contents from a colorectal anastomosis between 2 hollow viscera diagnosed radiologically, clinically, endoscopically, or intraoperatively. Pelvic abscesses were also considered to be an anastomotic leak. Radiologic examination was performed when there was clinical suspicion of leak. Anastomotic leak occurred in 6.1% of patients, of which 33 (67%) were treated operatively, 6 (12%) with radiologic drains, and 10 (21%) by medical treatment. Postoperative mortality rate was 2.9% for the whole group of 800 patients. In patients with anastomotic leak, mortality rate increased up to 16% vs 2.0% in patients without anastomotic leak (P < .0001). At multivariate analysis, rectal location of tumor, male sex, bowel obstruction preoperatively, tobacco use, diabetes, perioperative transfusion, and the individual surgeon were independent risk factors for anastomotic leak. The surgeon was the most important factor (mean odds ratio 4.9; range 1.0 to 13.5). The variance of anastomotic leak between the different surgeons was 0.56 in the logit scale. The individual surgeon is an independent risk factor for leakage in double-stapled, colorectal, end-to-end anastomosis after oncologic left-sided colorectal resection. Copyright © 2017 Elsevier Inc. All rights reserved.

Experiences with leak rate calculations methods for LBB application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grebner, H.; Kastner, W.; Hoefler, A.

1997-04-01

In this paper, three leak rate computer programs for the application of leak before break analysis are described and compared. The programs are compared to each other and to results of an HDR Reactor experiment and two real crack cases. The programs analyzed are PIPELEAK, FLORA, and PICEP. Generally, the different leak rate models are in agreement. To obtain reasonable agreement between measured and calculated leak rates, it was necessary to also use data from detailed crack investigations.

Real-time electronic monitoring of a pitted and leaking gas gathering pipeline

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asperger, R.G.; Hewitt, P.G.

1986-08-01

Hydrogen patch, flush electrical resistance, and flush linear polarization proves wre used with flush coupons to monitor corrosion rates in a pitted and leaking sour gas gathering line. Four inhibitors were evaluated in stopping the leaks. Inhibitor residuals and the amount and ratio of water and condensate in the lines were measured at five locations along the line. The best inhibitor reduced reduced the pit-leak frequency by over a factor of 10. Inhibitor usage rate was optimized using the hydrogen patch current as a measure of the instantaneous corrosion rate. Improper pigging was identified as a cause of corrosion transients.more » This problem is discussed in relation to the pigging of pipelines in stratified flow where moving fluids are the carriers for continuously injected corrosion inhibitors.« less

Risk of anastomotic leak after laparoscopic versus open colectomy.

PubMed

Murray, Alice C A; Chiuzan, Cody; Kiran, Ravi P

2016-12-01

Anastomotic leak following colorectal surgery is associated with significant morbidity and mortality. With the widespread adoption of laparoscopy, data from initial clinical trials evaluating the efficacy of laparoscopic when compared to open surgery may not currently be generalizable. We assess the risk of anastomotic leak after laparoscopic versus open colorectal resection using a nationwide database with standardized definitions. The 2012-2013 ACS-NSQIP targeted colectomy data were queried for all elective colorectal resections. Characteristics were compared for those patients undergoing laparoscopic versus open operations. Univariable and multivariable analyses, followed by a propensity score-matched analysis, were performed to assess the impact of laparoscopy on the development of an anastomotic leak. Of 23,568 patients, 3.4 % developed an anastomotic leak. Laparoscopic surgery was associated with a leak rate of 2.8 % (n = 425) and open surgery, 4.5 % (n = 378, p < 0.0001). Patients who developed a leak were more likely to die within 30 days of surgery (5.7 vs. 0.6 %, p < 0.0001). Patients who underwent laparoscopic surgery compared to open were younger (61 vs. 63 years, p = 0, p = 0.045) and with fewer comorbidities. On univariable analysis laparoscopic surgery was associated with reduced odds of developing an anastomotic leak (OR 0.60, p < 0.0001), and this remained after adjusting for all significant preoperative and disease-related confounders (OR 0.69, 95 % CI 0.58-0.82). A propensity score-matched analysis confirmed benefit of laparoscopic surgery over open surgery for anastomotic leak. Laparoscopic colectomy is safe and associated with reduced odds of developing an anastomotic leak following colectomy when controlling for patient-, disease- and procedure-related factors.

Cerebrospinal fluid cutaneous fistula following obstetric epidural analgaesia. Case report.

PubMed

Fedriani de Matos, J J; Quintero Salvago, A V; Gómez Cortés, M D

2017-10-01

Cutaneous fistula of cerebrospinal fluid is a rare complication of neuroaxial blockade. We report the case of a parturient in whom an epidural catheter was placed for labour analgesia and 12h after the catheter was removed, presented an abundant asymptomatic fluid leak from the puncture site, compatible in the cyto-chemical analysis with cerebrospinal fluid. She was treated with acetazolamide, compression of skin orifice of the fluid leakage, antibiotic prophylaxis, hydration and rest, and progressed satisfactorily without requiring blood patch. Copyright © 2017 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

Intracranial hypotension headache caused by a massive cerebrospinal fluid leak successfully treated with a targeted c2 epidural blood patch: a case report.

PubMed

Sykes, Kenneth T; Yi, Xiaobin

2013-01-01

Cervical epidural steroid injections, administered either interlaminarly or transforaminally, are common injection therapies used in many interventional pain management practices to treat cervicalgia or cervicobrachial pain secondary to spondylosis or intervertebral disc displacement of the cervical spine. Among the risks associated with these procedures are the risk for inadvertent dural puncture and the development of positional headache from intracranial hypotension. We report the case of a 31-year-old woman with a history of migraine and cervicalgia from cervical spine spondylosis and cervical disc degenerative disease that developed an intractable orthostatic headache accompanied by nausea and vomiting after a therapeutic high cervical intralaminar epidural steroid injection was administered directly to the C1-C2 spinal level. Although the initial magnetic resonance imaging of the brain was unremarkable, a computed tomography myelogram study revealed a massive cerebrospinal fluid (CSF) leak from the cervical spine.  Repeated cervical epidural blood patches using a catheter targeted to the high cervical spine (C2) to inject 15 mL of autologous blood was required to totally alleviate her symptoms after she failed conservative therapy. Determining the optimal location or approach to administer an epidural blood patch can be a challenge depending on the location of the CSF leak. Our case demonstrates that targeted cervical epidural blood patch placement using an easily manipulated catheter under fluoroscopic guidance is a safe and effective approach to treat a massive CSF leak in the high cervical spine region caused by prior therapeutic cervical spine epidural steroid injection.

Impact of anastomotic leak on recurrence and survival after colorectal cancer surgery: a BioGrid Australia analysis.

PubMed

Sammour, Tarik; Hayes, Ian P; Jones, Ian T; Steel, Malcolm C; Faragher, Ian; Gibbs, Peter

2018-01-01

There is conflicting evidence regarding the oncological impact of anastomotic leak following colorectal cancer surgery. This study aims to test the hypothesis that anastomotic leak is independently associated with local recurrence and overall and cancer-specific survival. Analysis of prospectively collected data from multiple centres in Victoria between 1988 and 2015 including all patients who underwent colon or rectal resection for cancer with anastomosis was presented. Overall and cancer-specific survival rates and rates of local recurrence were compared using Cox regression analysis. A total of 4892 patients were included, of which 2856 had completed 5-year follow-up. The overall anastomotic leak rate was 4.0%. Cox regression analysis accounting for differences in age, sex, body mass index, American Society of Anesthesiologists score and tumour stage demonstrated that anastomotic leak was associated with significantly worse 5-year overall survival (χ 2 = 6.459, P = 0.011) for colon cancer, but only if early deaths were included. There was no difference in 5-year colon cancer-specific survival (χ 2 = 0.582, P = 0.446) or local recurrence (χ 2 = 0.735, P = 0.391). For rectal cancer, there was no difference in 5-year overall survival (χ 2 = 0.266, P = 0.606), cancer-specific survival (χ 2 = 0.008, P = 0.928) or local recurrence (χ 2 = 2.192, P = 0.139). Anastomotic leak may reduce 5-year overall survival in colon cancer patients but does not appear to influence the 5-year overall survival in rectal cancer patients. There was no effect on local recurrence or cancer-specific survival. © 2016 Royal Australasian College of Surgeons.

Fluid Inclusion Gas Analysis

DOE Data Explorer

Dilley, Lorie

2013-01-01

Fluid inclusion gas analysis for wells in various geothermal areas. Analyses used in developing fluid inclusion stratigraphy for wells and defining fluids across the geothermal fields. Each sample has mass spectrum counts for 180 chemical species.

Coupled Model for CO2 Leaks from Geological Storage: Geomechanics, Fluid Flow and Phase Transitions

NASA Astrophysics Data System (ADS)

Gor, G.; Prevost, J.

2013-12-01

Deep saline aquifers are considered as a promising option for long-term storage of carbon dioxide. However, risk of CO2 leakage from the aquifers through faults, natural or induced fractures or abandoned wells cannot be disregarded. Therefore, modeling of various leakage scenarios is crucial when selecting a site for CO2 sequestration and choosing proper operational conditions. Carbon dioxide is injected into wells at supercritical conditions (t > 31.04 C, P > 73.82 bar), and these conditions are maintained in the deep aquifers (at 1-2 km depth) due to hydrostatic pressure and geothermal gradient. However, if CO2 and brine start to migrate from the aquifer upward, both pressure and temperature will decrease, and at the depth of 500-750 m, the conditions for CO2 will become subcritical. At subcritical conditions, CO2 starts boiling and the character of the flow changes dramatically due to appearance of the third (vapor) phase and latent heat effects. When modeling CO2 leaks, one needs to couple the multiphase flow in porous media with geomechanics. These capabilities are provided by Dynaflow, a finite element analysis program [1]; Dynaflow has already showed to be efficient for modeling caprock failure causing CO2 leaks [2, 3]. Currently we have extended the capabilities of Dynaflow with the phase transition module, based on two-phase and three-phase isenthalpic flash calculations [4]. We have also developed and implemented an efficient method for solving heat and mass transport with the phase transition using our flash module. Therefore, we have developed a robust tool for modeling CO2 leaks. In the talk we will give a brief overview of our method and illustrate it with the results of simulations for characteristic test cases. References: [1] J.H. Prevost, DYNAFLOW: A Nonlinear Transient Finite Element Analysis Program. Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ. http://www.princeton.edu/~dynaflow/ (last update 2013

Sleeve gastrectomy and the risk of leak: a systematic analysis of 4,888 patients.

PubMed

Aurora, Alexander R; Khaitan, Leena; Saber, Alan A

2012-06-01

Sleeve gastrectomy has become a popular stand-alone bariatric procedure with comparable weight loss and resolution of comorbidities to that of laparoscopic gastric bypass. The simplicity of the procedure and the decreased long-term risk profile make this surgery more appealing. Nonetheless, the ever present risk of a staple-line leak is still of great concern and needs further investigation. An electronic literature search of MEDLINE database plus manual reference checks of articles published on laparoscopic sleeve gastrectomy for morbid obesity and its complications was completed. Keywords used in the search were "sleeve gastrectomy" OR "gastric sleeve" AND "leak." We analyzed 29 publications, including 4,888 patients. We analyzed the frequency of leak after sleeve gastrectomy and its associated risks of causation. The risk of leak after sleeve gastrectomy in all comers was 2.4%. This risk was 2.9% in the super-obese [body mass index (BMI) > 50 kg/m(2)] and 2.2% for BMI < 50 kg/m(2). Staple height and use of buttressing material did not affect leak rate. The use of a size 40-Fr or greater bougie was associated with a leak rate of 0.6% compared with those who used smaller sizes whose leak rate was 2.8%. Leaks were found at the proximal third of the stomach in 89% of cases. Most leaks were diagnosed after discharge. Endoscopic management is a viable option for leaks and was documented in 11% of cases as successful. Sleeve gastrectomy has become an important surgical option for the treatment of the ever growing morbidly obese population. The risk of leak is low at 2.4%. Attention to detail specifically at the esophagogastric junction cannot be stressed enough. Careful patient selection (BMI < 50 kg/m(2)) and adopting the use of a 40-Fr or larger bougie may decrease the risk of leak. Vigilant follow-up during the first 30 days is critical to avoid catastrophe, because most leaks will happen after patient discharge.

Spontaneous CSF-leaks and meningoencephaloceles in sphenoid sinus by persisting Sternberg's canal.

PubMed

Tomazic, Peter Valentin; Stammberger, Heinz

2009-12-01

Cerebrospinal fluid (CSF) leaks and meningoencephaloceles of the lateral recess of sphenoid sinuses are rare findings. A congenital bony defect in the lateral wall of sphenoid sinus called Sternberg's canal could be the origin of these lesions. Their endoscopic transnasal management is challenging though less traumatic than transcranial approaches. The aim of this study was to define Sternberg's canal as a potential source for these rare lesions and to describe their endoscopic endonasal management. In a retrospective analysis clinical charts of 27 patients with CSF-leaks and / or meningoencephaloceles operated between March 2002 and October 2008 at the University ENT-hospital Graz have been reviewed. All patients were treated by an endoscopic endonasal approach. Five patients (4 female / 1 male) were identified with spontaneous CSF-leaks from sphenoid sinus and meningoencephaloceles. In all five cases, Sternberg's canal was the site of leakage, with the bony and dural defects always located laterally between the maxillary and Vidian nerves. Mean age was 51.2 years and mean body mass index (BMI) was 31.9 kg/m2. All patients were operated using a multilayer closure technique. Two patients had recurrences after 12 days and 7 months, respectively, managed by endoscopic revision surgery resulting in a 100% closure rate after one revision (mean follow-up: 6.5 months). Persisting Sternberg's canal can be the source of spontaneous CSF-leaks and meningoencephaloceles in the lateral recess of sphenoid sinus especially when associated with extensive pneumatisation. Endoscopic management is technically challenging, nevertheless its advantages are a good view of the surgical field while being less traumatic than transcranial approaches.

Leak rate of seals: Effective-medium theory and comparison with experiment.

PubMed

Lorenz, B; Persson, B N J

2010-02-01

Seals are extremely useful devices to prevent fluid leakage. We present an effective-medium theory of the leak rate of rubber seals, which is based on a recently developed contact mechanics theory. We compare the theory with experimental results for seals consisting of silicon rubber in contact with sandpaper and sand-blasted PMMA surfaces.

Outcomes of endoscopic repair of cerebrospinal fluid rhinorrhea without lumbar drains.

PubMed

Adams, Austin S; Russell, Paul T; Duncavage, James A; Chandra, Rakesh K; Turner, Justin H

2016-11-01

Lumbar drains (LD) are commonly used during endoscopic repair of cerebrospinal fluid (CSF) rhinorrhea, either to facilitate graft healing or to monitor CSF fluid dynamics. However, the indications and necessity of LD placement remains controversial. The current study sought to evaluate endoscopic CSF leak repair outcomes in the setting of limited LD use. Patients who underwent endoscopic repair of CSF rhinorrhea between 2004 and 2014 were identified by a review of medical records. Demographic and clinical data were extracted and compared between patients who had surgery with and patients who had surgery without a perioperative LD. A univariate analysis was performed to identify factors predictive of recurrence. A total of 107 patients (116 surgical procedures) were identified, with a mean follow-up of 15.8 months. Eighty-eight of 107 patients (82.2%) had surgery without an LD. The mean hospital stay was 4.48 days in the LD group versus 1.03 days in the non-LD group (p < 0.00001). There was no difference in recurrence rate between the LD and non-LD groups. Predictors of recurrence included repair technique (p = 0.04) and size of defect (p = 0.005). Body mass index, leak site (ethmoid, sphenoid, frontal), and etiology (spontaneous, iatrogenic, traumatic) were not predictive of leak recurrence. Use of LDs in endoscopic CSF leak repair was not associated with reduced recurrence rates, regardless of leak etiology, and resulted in a significant increase in hospital length of stay. Although the use of perioperative LDs to monitor CSF dynamics may have some therapeutic and diagnostic advantages, it may not be associated with clinically significant improvements in patient outcomes or recurrence rates.

Detecting Methane Leaks

NASA Technical Reports Server (NTRS)

Grant, W. B.; Hinkley, E. D.

1984-01-01

Remote sensor uses laser radiation backscattered from natural targets. He/Ne Laser System for remote scanning of Methane leaks employs topographic target to scatter light to receiver near laser transmitter. Apparatus powered by 1.5kW generator transported to field sites and pointed at suspected methane leaks. Used for remote detection of natural-gas leaks and locating methane emissions in landfill sites.

Modeling and measurement of the performance of a branched conduit sampling system in a mass spectrometer leak detector

NASA Technical Reports Server (NTRS)

Russell, John M.

1994-01-01

In the leak testing of a large engineering system, one may distinguish three stages, namely leakage measurement by an overall enclosure, leak location, and leakage measurement by a local enclosure. Sniffer probes attached to helium mass spectrometer leak detectors are normally designed for leak location, a qualitative inspection technique intended to pinpoint where a leak is but not to quantify its rate of discharge. The main conclusion of the present effort is that local leakage measurement by a leak detector with a sniffer probe is feasible provided one has: (1) quantitative data on the performance of the mass separator cell (a device interior to the unit where the stream of fluid in the sample line branches); and (2) a means of stabilizing the mass transfer boundary layer that is created near a local leak site when a sniffer probe is placed in its immediate vicinity. Theoretical models of the mass separator cell are provided and measurements of the machine-specific parameters in the formulas are presented. A theoretical model of a porous probe end for stabilizing the mass transfer boundary is also presented.

Modeling and measurement of the performance of a branched conduit sampling system in a mass spectrometer leak detector

NASA Astrophysics Data System (ADS)

Russell, John M.

1994-10-01

In the leak testing of a large engineering system, one may distinguish three stages, namely leakage measurement by an overall enclosure, leak location, and leakage measurement by a local enclosure. Sniffer probes attached to helium mass spectrometer leak detectors are normally designed for leak location, a qualitative inspection technique intended to pinpoint where a leak is but not to quantify its rate of discharge. The main conclusion of the present effort is that local leakage measurement by a leak detector with a sniffer probe is feasible provided one has: (1) quantitative data on the performance of the mass separator cell (a device interior to the unit where the stream of fluid in the sample line branches); and (2) a means of stabilizing the mass transfer boundary layer that is created near a local leak site when a sniffer probe is placed in its immediate vicinity. Theoretical models of the mass separator cell are provided and measurements of the machine-specific parameters in the formulas are presented. A theoretical model of a porous probe end for stabilizing the mass transfer boundary is also presented.

Endotracheal tube leak pressure and tracheal lumen size in swine.

PubMed

Finholt, D A; Audenaert, S M; Stirt, J A; Marcella, K L; Frierson, H F; Suddarth, L T; Raphaely, R C

1986-06-01

Endotracheal tube "leak" is often estimated in children to judge the fit of uncuffed endotracheal tubes within the trachea. Twenty-five swine were intubated with uncuffed tracheal tubes to determine whether a more sensitive measurement of leaks could be devised and whether leak pressure estimates fit between tracheal tube and trachea. We compared leak pressure measurement using a stethoscope and aneroid manometer with a technique using a microphone, pressure transducer, and recorder, and found no differences between the two methods. The tracheas were then removed and slides prepared of tracheal cross-sectional specimens. Regression analysis revealed a linear relationship between tracheal lumen size and tracheal tube size for both low leak pressure (y = -0.4 + 0.79x, r = 0.88, P less than 0.05) and high leak pressure (y = -2.9 + 0.71x, r = 0.92, P less than 0.05) groups. We conclude that leak testing with a stethoscope and aneroid manometer is sensitive and accurate, and that tracheal tube leak pressure accurately portrays fit between tube and trachea.

Leak-off mechanism and pressure prediction for shallow sediments in deepwater drilling

NASA Astrophysics Data System (ADS)

Tan, Qiang; Deng, Jingen; Sun, Jin; Liu, Wei; Yu, Baohua

2018-02-01

Deepwater sediments are prone to loss circulation in drilling due to a low overburden gradient. How to predict the magnitude of leak-off pressure more accurately is an important issue in the protection of drilling safety and the reduction of drilling cost in deep water. Starting from the mechanical properties of a shallow formation and based on the basic theory of rock-soil mechanics, the stress distribution around a borehole was analyzed. It was found that the rock or soil on a borehole is in the plastic yield state before the effective tensile stress is generated, and the effective tangential and vertical stresses increase as the drilling fluid density increases; thus, tensile failure will not occur on the borehole wall. Based on the results of stress calculation, two mechanisms and leak-off pressure prediction models for shallow sediments in deepwater drilling were put forward, and the calculated values of these models were compared with the measured value of shallow leak-off pressure in actual drilling. The results show that the MHPS (minimum horizontal principle stress) model and the FIF (fracturing in formation) model can predict the lower and upper limits of leak-off pressure. The PLC (permeable lost circulation) model can comprehensively analyze the factors influencing permeable leakage and provide a theoretical basis for leak-off prevention and plugging in deepwater drilling.

SSME propellant path leak detection real-time

NASA Technical Reports Server (NTRS)

Crawford, R. A.; Smith, L. M.

1994-01-01

Included are four documents that outline the technical aspects of the research performed on NASA Grant NAG8-140: 'A System for Sequential Step Detection with Application to Video Image Processing'; 'Leak Detection from the SSME Using Sequential Image Processing'; 'Digital Image Processor Specifications for Real-Time SSME Leak Detection'; and 'A Color Change Detection System for Video Signals with Applications to Spectral Analysis of Rocket Engine Plumes'.

Mapping urban pipeline leaks: methane leaks across Boston.

PubMed

Phillips, Nathan G; Ackley, Robert; Crosson, Eric R; Down, Adrian; Hutyra, Lucy R; Brondfield, Max; Karr, Jonathan D; Zhao, Kaiguang; Jackson, Robert B

2013-02-01

Natural gas is the largest source of anthropogenic emissions of methane (CH(4)) in the United States. To assess pipeline emissions across a major city, we mapped CH(4) leaks across all 785 road miles in the city of Boston using a cavity-ring-down mobile CH(4) analyzer. We identified 3356 CH(4) leaks with concentrations exceeding up to 15 times the global background level. Separately, we measured δ(13)CH(4) isotopic signatures from a subset of these leaks. The δ(13)CH(4) signatures (mean = -42.8‰ ± 1.3‰ s.e.; n = 32) strongly indicate a fossil fuel source rather than a biogenic source for most of the leaks; natural gas sampled across the city had average δ(13)CH(4) values of -36.8‰ (± 0.7‰ s.e., n = 10), whereas CH(4) collected from landfill sites, wetlands, and sewer systems had δ(13)CH(4) signatures ~20‰ lighter (μ = -57.8‰, ± 1.6‰ s.e., n = 8). Repairing leaky natural gas distribution systems will reduce greenhouse gas emissions, increase consumer health and safety, and save money. Copyright © 2012 Elsevier Ltd. All rights reserved.

Mitochondrial proton and electron leaks.

PubMed

Jastroch, Martin; Divakaruni, Ajit S; Mookerjee, Shona; Treberg, Jason R; Brand, Martin D

2010-01-01

Mitochondrial proton and electron leak have a major impact on mitochondrial coupling efficiency and production of reactive oxygen species. In the first part of this chapter, we address the molecular nature of the basal and inducible proton leak pathways, and their physiological importance. The basal leak is unregulated, and a major proportion can be attributed to mitochondrial anion carriers, whereas the proton leak through the lipid bilayer appears to be minor. The basal proton leak is cell-type specific and correlates with metabolic rate. The inducible leak through the ANT (adenine nucleotide translocase) and UCPs (uncoupling proteins) can be activated by fatty acids, superoxide or lipid peroxidation products. The physiological role of inducible leak through UCP1 in mammalian brown adipose tissue is heat production, whereas the roles of non-mammalian UCP1 and its paralogous proteins, in particular UCP2 and UCP3, are not yet resolved. The second part of the chapter focuses on the electron leak that occurs in the mitochondrial electron transport chain. Exit of electrons prior to the reduction of oxygen to water at cytochrome c oxidase causes superoxide production. As the mechanisms of electron leak are crucial to understanding their physiological relevance, we summarize the mechanisms and topology of electron leak from complexes I and III in studies using isolated mitochondria. We also highlight recent progress and challenges of assessing electron leak in the living cell. Finally, we emphasize the importance of proton and electron leak as therapeutic targets in body mass regulation and insulin secretion.

Combining supercritical fluid extraction of soil herbicides with enzyme immunoassay analysis.

PubMed

Stearman, G K

2001-10-01

Supercritical fluid extraction (SFE) of soil herbicides followed by enzyme immunoassay analysis (EIA) is explained in a step-by-step process. Extracted herbicides, include 2,4-D, simazine, atrazine, and alachlor. The herbicide, trifluralin was not successfully analyzed by EIA because of crossreacting metabolites. Problems with SFE, including uneven packing of cells, leaks, uneven flow and clogging, can largely be eliminated as the method parameters are optimized. It was necessary to add modifiers including methanol or acetone to the SF CO2 to increase the solubility of the analytes. Detection limits of 2.5 ng/g soil for atrazine and alachlor and 15 ng/g soil for simazine and 2,4-D without concentration of the sample were achieved. Recoveries above 80% and relative standard deviations (RSDs) less than 15% for 2,4-D simazine, atrazine and alachlor were achieved. Atrazine and alachlor recoveries were above 90% with RSDs below 10%. Forty soil samples could be extracted and analyzed in an 8-h day.

Air-Leak Effects on Ear-Canal Acoustic Absorbance

PubMed Central

Rasetshwane, Daniel M.; Kopun, Judy G.; Gorga, Michael P.; Neely, Stephen T.

2015-01-01

Objective: Accurate ear-canal acoustic measurements, such as wideband acoustic admittance, absorbance, and otoacoustic emissions, require that the measurement probe be tightly sealed in the ear canal. Air leaks can compromise the validity of the measurements, interfere with calibrations, and increase variability. There are no established procedures for determining the presence of air leaks or criteria for what size leak would affect the accuracy of ear-canal acoustic measurements. The purpose of this study was to determine ways to quantify the effects of air leaks and to develop objective criteria to detect their presence. Design: Air leaks were simulated by modifying the foam tips that are used with the measurement probe through insertion of thin plastic tubing. To analyze the effect of air leaks, acoustic measurements were taken with both modified and unmodified foam tips in brass-tube cavities and human ear canals. Measurements were initially made in cavities to determine the range of critical leaks. Subsequently, data were collected in ears of 21 adults with normal hearing and normal middle-ear function. Four acoustic metrics were used for predicting the presence of air leaks and for quantifying these leaks: (1) low-frequency admittance phase (averaged over 0.1–0.2 kHz), (2) low-frequency absorbance, (3) the ratio of compliance volume to physical volume (CV/PV), and (4) the air-leak resonance frequency. The outcome variable in this analysis was the absorbance change (Δabsorbance), which was calculated in eight frequency bands. Results: The trends were similar for both the brass cavities and the ear canals. ΔAbsorbance generally increased with air-leak size and was largest for the lower frequency bands (0.1–0.2 and 0.2–0.5 kHz). Air-leak effects were observed in frequencies up to 10 kHz, but their effects above 1 kHz were unpredictable. These high-frequency air leaks were larger in brass cavities than in ear canals. Each of the four predictor variables

Air-leak effects on ear-canal acoustic absorbance.

PubMed

Groon, Katherine A; Rasetshwane, Daniel M; Kopun, Judy G; Gorga, Michael P; Neely, Stephen T

2015-01-01

Accurate ear-canal acoustic measurements, such as wideband acoustic admittance, absorbance, and otoacoustic emissions, require that the measurement probe be tightly sealed in the ear canal. Air leaks can compromise the validity of the measurements, interfere with calibrations, and increase variability. There are no established procedures for determining the presence of air leaks or criteria for what size leak would affect the accuracy of ear-canal acoustic measurements. The purpose of this study was to determine ways to quantify the effects of air leaks and to develop objective criteria to detect their presence. Air leaks were simulated by modifying the foam tips that are used with the measurement probe through insertion of thin plastic tubing. To analyze the effect of air leaks, acoustic measurements were taken with both modified and unmodified foam tips in brass-tube cavities and human ear canals. Measurements were initially made in cavities to determine the range of critical leaks. Subsequently, data were collected in ears of 21 adults with normal hearing and normal middle-ear function. Four acoustic metrics were used for predicting the presence of air leaks and for quantifying these leaks: (1) low-frequency admittance phase (averaged over 0.1-0.2 kHz), (2) low-frequency absorbance, (3) the ratio of compliance volume to physical volume (CV/PV), and (4) the air-leak resonance frequency. The outcome variable in this analysis was the absorbance change (Δabsorbance), which was calculated in eight frequency bands. The trends were similar for both the brass cavities and the ear canals. ΔAbsorbance generally increased with air-leak size and was largest for the lower frequency bands (0.1-0.2 and 0.2-0.5 kHz). Air-leak effects were observed in frequencies up to 10 kHz, but their effects above 1 kHz were unpredictable. These high-frequency air leaks were larger in brass cavities than in ear canals. Each of the four predictor variables exhibited consistent dependence on

Cost-effectiveness analysis of stent type in endoscopic treatment of gastric leak after laparoscopic sleeve gastrectomy.

PubMed

Cosse, C; Rebibo, L; Brazier, F; Hakim, S; Delcenserie, R; Regimbeau, J M

2018-04-01

Gastric leak is the most feared surgical postoperative complication after sleeve gastrectomy. An endoscopic procedure is usually required to treat the leak. No data are available on the cost-effectiveness of different stent types in this procedure. Between April 2005 and July 2016, patients with a confirmed gastric leak undergoing endoscopic treatment using a covered stent (CS) or double-pigtail stent (DPS) were included. The primary objective of the study was to assess overall costs of the stent types after primary sleeve gastrectomy. Secondary objectives were the cost-effectiveness of each stent type expressed as an incremental cost-effectiveness ratio (ICER); the incremental net benefit; the probability of efficiency, defined as the probability of being cost-effective at a threshold of €30 000, and identification of the key drivers of ICER derived from a multivariable analysis. One hundred and twelve patients were enrolled. The overall mean costs of gastric leak were €22 470; the mean(s.d.) cost was €24 916(12 212) in the CS arm and €20 024(3352) in the DPS arm (P = 0·018). DPS was more cost-effective than CS (ICER €4743 per endoscopic procedure avoided), with an incremental net benefit of €25 257 and a 27 per cent probability of efficiency. Key drivers of the ICER were the inpatient ward after diagnosis of gastric leak (surgery versus internal medicine), type of institution (private versus public) and duration of hospital stay per endoscopic procedure. DPS for the treatment of gastric leak is more cost-effective than CS and should be proposed as the standard regimen whenever possible. © 2018 BJS Society Ltd Published by John Wiley & Sons Ltd.

Leak testing in parenteral packaging: establishment of direct correlation between helium leak rate measurements and microbial ingress for two different leak types.

PubMed

Morrical, Bradley D; Goverde, Marcel; Grausse, Jean; Gerwig, Tanja; Vorgrimler, Lothar; Morgen, Rachel; Büttiker, Jean-Pierre

2007-01-01

A direct test method using helium leak detection was developed to determine microbial ingress in parenteral vial/rubber closure systems. The purpose of this study was to establish a direct correlation between the helium leak rate and the presence of ingress when vials were submersed under pressure in a broth of bacteria. Results were obtained for two different types of leaks: microholes that have been laser-drilled into thin metal plates, and thin copper wire that was placed between the rubber closure and the glass vial's sealing surface. The results from the microholes showed that the helium leak rate was a function of the square of the hole diameter and fit well with theoretical calculations. The relationship with the wire gave a far more complex dependence and was not modeled theoretically. Comparison with the microbial challenge showed that for microholes a lower size limit was found to be 2 microm with a corresponding leak rate of 1.4 x 10(-3) mbarl/s. For the fine wire experiment the lower limit was 15-microm wire and a corresponding leak rate of 1.3 x 10(-5) mbarl/s. From these tests a safe, lower limit, leak rate was established.

Evaluation of an Interferometric Sensor for In-Space Detection of Gas Leaks

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Korman, Valentin; Sinko, John; Hendrickson, Adam

2009-01-01

Space mission planning often involves long-term storage of volatile liquids or high-pressure gases. These may include cryogenic fuels and oxidizers, high-pressure gases, and life-support-critical consumables. The risk associated with the storage of fluids and gases in space systems has long been an issue and the ability to retain these fluids is often tied to mission success. A leak in the storage or distribution system can cause many different problems, including a simple, but mission endangering, loss of inventory or, in severe cases, unbalanced thrust loads on a flight vehicle. Cryogenic propellants are especially difficult to store, especially over a long duration. The propellant can boil off and be lost through the insulating walls of the tank or simple thermal cycling of the fittings, valves, and propellant feed lines may unseat seals allowing the fluid to escape. Current NASA missions call for long-duration in-space storage of propellants, oxidizers, and life support supplies. Leaks of a scale detectable through a pressure drop in the storage tank are often catastrophic and have long been the focus of ground-based mitigation efforts where redundant systems are often employed. However, there is presently no technology available for detecting and monitoring low-level, but still mission-endangering, gas leaks in space. Standard in-space gas detection methods either have a very limited pressure range over which they operate effectively or are limited to certain gases. Mass spectrometer systems are able to perform the detection tasks, but their size, mass and use of high voltage, which could potentially lead to an arc that ignites a combustible propellent, severely limit their usefulness in a space system. In this paper, we present results from testing of the light-based interferometric gas monitoring and leak detection sensor shown in Fig. 1. The output of the sensor is an interference fringe pattern that is a function of the gas density, and commensurate index

Transthoracic Anastomotic Leak After Esophagectomy: Current Trends.

PubMed

Ryan, Carrie E; Paniccia, Alessandro; Meguid, Robert A; McCarter, Martin D

2017-01-01

Leaks from intrathoracic esophagogastric anastomosis are thought to be associated with higher rates of morbidity and mortality than leaks from cervical anastomosis. We challenge this assumption and hypothesize that there is no significant difference in mortality based on the location of the esophagogastric anastomosis. A systematic literature search was conducted using PubMed and Embase databases on all studies published from January 2000 to June 2015, comparing transthoracic (TTE) and transhiatal (THE) esophagectomies. Studies using jejunal or colonic interposition were excluded. Outcomes analyzed were leak rate, leak-associated mortality, overall 30-day mortality, and overall morbidity. Meta-analyses were performed using Mantel-Haenszel statistical analyses on studies reporting leak rates of both approaches. Nominal data are presented as frequency and interquartile range (IQR); measures of the association between treatments and outcomes are presented as odds ratio (OR) with 95 % confidence interval. Twenty-one studies (3 randomized controlled trials) were analyzed comprising of 7167 patients (54 % TTE). TTE approach yields a lower anastomotic leak rate (9.8 %; IQR 6.0-12.2 %) than THE (12 %; IQR 11.6-22.1 %; OR 0.56 [0.34-0.92]), without any significant difference in leak associated mortality (7.1 % TTE vs. 4.6 % THE: OR 1.83 [0.39-8.52]). There was no difference in overall 30-day mortality (3.9 % TTE vs. 4.3 % THE; OR 0.86 [0.66-1.13]) and morbidity (59.0 % TTE vs. 66.6 % THE; OR 0.76 [0.37-1.59]). Based on meta-analysis, TTE is associated with a lower leak rate and does not result in higher morbidity or mortality than THE. The previously assumed higher rate of transthoracic anastomotic leak-associated mortality is overstated, thus supporting surgeon discretion and other factors to influence the choice of thoracic versus cervical anastomosis.

Routine intraoperative leak testing for sleeve gastrectomy: is the leak test full of hot air?

PubMed

Bingham, Jason; Lallemand, Michael; Barron, Morgan; Kuckelman, John; Carter, Preston; Blair, Kelly; Martin, Matthew

2016-05-01

Staple line leak after sleeve gastrectomy (SG) is a rare but dreaded complication with a reported incidence of 0% to 8%. Many surgeons routinely test the staple line with an intraoperative leak test (IOLT), but there is little evidence to validate this practice. In fact, there is a theoretical concern that the leak test may weaken the staple line and increase the risk of a postop leak. Retrospective review of all SGs performed over a 7-year period was conducted. Cases were grouped by whether an IOLT was performed, and compared for the incidence of postop staple line leaks. The ability of the IOLT for identifying a staple line defect and for predicting a postoperative leak was analyzed. Five hundred forty-two SGs were performed between 2007 and 2014. Thirteen patients (2.4%) developed a postop staple line leak. The majority of patients (n = 494, 91%) received an IOLT, including all 13 patients (100%) who developed a subsequent clinical leak. There were no (0%) positive IOLTs and no additional interventions were performed based on the IOLT. The IOLT sensitivity and positive predictive value were both 0%. There was a trend, although not significant, to increase leak rates when a routine IOLT was performed vs no routine IOLT (2.6% vs 0%, P = .6). The performance of routine IOLT after SG provided no actionable information, and was negative in all patients who developed a postoperative leak. The routine use of an IOLT did not reduce the incidence of postop leak, and in fact was associated with a higher leak rate after SG. Published by Elsevier Inc.

Prospective randomized trial compares suction versus water seal for air leaks.

PubMed

Cerfolio, R J; Bass, C; Katholi, C R

2001-05-01

Surgeons treat air leaks differently. Our goal was to evaluate whether it is better to place chest tubes on suction or water seal for stopping air leaks after pulmonary surgery. A second goal was to evaluate a new classification system for air leaks that we developed. Patients were prospectively randomized before surgery to receive suction or water seal to their chest tubes on postoperative day (POD) #2. Air leaks were described and quantified daily by a classification system and a leak meter. The air-leak meter scored leaks from 1 (least) to 7 (greatest). The group randomized to water seal stayed on water seal unless a pneumothorax developed. On POD #2, 33 of 140 patients had an air leak. Eighteen patients had been preoperatively randomized to water seal and 15 to suction. Air leaks resolved in 12 (67%) of the water seal patients by the morning of POD #3. All 6 patients whose air leak did not stop had a leak that was 4/7 or greater (p < 0.0001) on the leak meter. Of the 15 patients randomized to suction, only 1 patient's air leak (7%) resolved by the morning of POD #3. The randomization aspect of the trial was ended and statistical analysis showed water seal was superior (p = 0.001). The remaining 14 patients were then placed to water seal and by the morning of POD #4, 13 patients' leaks had stopped. Of the 32 total patients placed to seal, 7 (22%) developed a pneumothorax and 6 of these 7 patients had leaks that were 4/7 or greater (p = 0.001). Placing chest tubes on water seal seems superior to wall suction for stopping air leaks after pulmonary resection. However, water seal does not stop expiratory leaks that are 4/7 or greater. Pneumothorax may occur when chest tubes are placed on seal with leaks this large.

Sodium leak channel, non-selective contributes to the leak current in human myometrial smooth muscle cells from pregnant women.

PubMed

Reinl, Erin L; Cabeza, Rafael; Gregory, Ismail A; Cahill, Alison G; England, Sarah K

2015-10-01

Uterine contractions are tightly regulated by the electrical activity of myometrial smooth muscle cells (MSMCs). These cells require a depolarizing current to initiate Ca(2+) influx and induce contraction. Cationic leak channels, which permit a steady flow of cations into a cell, are known to cause membrane depolarization in many tissue types. Previously, a Gd(3+)-sensitive, Na(+)-dependent leak current was identified in the rat myometrium, but the presence of such a current in human MSMCs and the specific ion channel conducting this current was unknown. Here, we report the presence of a Na(+)-dependent leak current in human myometrium and demonstrate that the Na(+)-leak channel, NALCN, contributes to this current. We performed whole-cell voltage-clamp on fresh and cultured MSMCs from uterine biopsies of term, non-laboring women and isolated the leak currents by using Ca(2+) and K(+) channel blockers in the bath solution. Ohmic leak currents were identified in freshly isolated and cultured MSMCs with normalized conductances of 14.6 pS/pF and 10.0 pS/pF, respectively. The myometrial leak current was significantly reduced (P < 0.01) by treating cells with 10 μM Gd(3+) or by superfusing the cells with a Na(+)-free extracellular solution. Reverse transcriptase PCR and immunoblot analysis of uterine biopsies from term, non-laboring women revealed NALCN messenger RNA and protein expression in the myometrium. Notably, ∼90% knockdown of NALCN protein expression with lentivirus-delivered shRNA reduced the Gd(3+)-sensitive leak current density by 42% (P < 0.05). Our results reveal that NALCN, in part, generates the leak current in MSMCs and provide the basis for future research assessing NALCN as a potential molecular target for modulating uterine excitability. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Postoperative air leak grading is useful to predict prolonged air leak after pulmonary lobectomy.

PubMed

Oh, Sang Gi; Jung, Yochun; Jheon, Sanghoon; Choi, Yunhee; Yun, Ju Sik; Na, Kook Joo; Ahn, Byoung Hee

2017-01-23

Results of studies to predict prolonged air leak (PAL; air leak longer than 5 days) after pulmonary lobectomy have been inconsistent and are of limited use. We developed a new scale representing the amount of early postoperative air leak and determined its correlation with air leak duration and its potential as a predictor of PAL. We grade postoperative air leak using a 5-grade scale. All 779 lobectomies from January 2005 to December 2009 with available medical records were reviewed retrospectively. We devised six 'SUM' variables using air leak grades in the initial 72 h postoperatively. Excluding unrecorded cases and postoperative broncho-pleural fistulas, there were 720 lobectomies. PAL occurred in 135 cases (18.8%). Correlation analyses showed each SUM variable highly correlated with air leak duration, and the SUM 4to9 , which was the sum of six consecutive values of air leak grades for every 8 h record on postoperative days 2 and 3, was proved to be the most powerful predictor of PAL; PAL could be predicted with 75.7% and 77.7% positive and negative predictive value, respectively, when SUM 4to9  ≥ 16. When 4 predictors derived from multivariable logistic regression of perioperative variables were combined with SUM 4to9 , there was no significant increase in predictability compared with SUM 4to9 alone. This simple new method to predict PAL using SUM 4to9 showed that the amount of early postoperative air leak is the most powerful predictor of PAL, therefore, grading air leak after pulmonary lobectomy is a useful method to predict PAL.

Measuring Small Leak Holes

NASA Technical Reports Server (NTRS)

Koch, D. E.; Stephenson, J. G.

1983-01-01

Hole sizes deduced from pressure measurements. Measuring apparatus consists of pitot tube attached to water-filled manometer. Compartment tested is pressurized with air. Pitot probe placed at known distance from leak. Dynamic pressure of jet measured at that point and static pressure measured in compartment. Useful in situations in which small leaks are tolerable but large leaks are not.

The Leaking-Toilet Challenge

ERIC Educational Resources Information Center

Roman, Harry T.

2008-01-01

Leaking toilets can cost homeowners big dollars--often before it is even realized. Homeowners do not necessarily hear it leaking. It just does, and when the water bill comes due, it can be a most unpleasant surprise. This article presents a classroom challenge to try to develop leak-detection ideas that would be inexpensive and easily added to…

A short review on a complication of lumbar spine surgery: CSF leak.

PubMed

Menon, Sajesh K; Onyia, Chiazor U

2015-12-01

Cerebrospinal fluid (CSF) leak is a common complication of surgery involving the lumbar spine. Over the past decades, there has been significant advancement in understanding the basis, management and techniques of treatment for post-operative CSF leak following lumbar spine surgery. In this article, we review previous work in the literature on the various factors and technical errors during or after lumbar spine surgery that may lead to this feared complication, the available options of management with focus on the various techniques employed, the outcomes and also to highlight on the current trends. We also discuss the presentation, factors contributing to its development, basic concepts and practical aspects of the management with emphasis on the different techniques of treatment. Different outcomes following various techniques of managing post-operative CSF leak after lumbar spine surgery have been well described in the literature. However, there is currently no most ideal technique among the available options. The choice of which technique to be applied in each case is dependent on each surgeon's cumulative experience as well as a clear understanding of the contributory underlying factors in each patient, the nature and site of the leak, the available facilities and equipment. Copyright © 2015 Elsevier B.V. All rights reserved.

Vehicle-based Methane Mapping Helps Find Natural Gas Leaks and Prioritize Leak Repairs

NASA Astrophysics Data System (ADS)

von Fischer, J. C.; Weller, Z.; Roscioli, J. R.; Lamb, B. K.; Ferrara, T.

2017-12-01

Recently, mobile methane sensing platforms have been developed to detect and locate natural gas (NG) leaks in urban distribution systems and to estimate their size. Although this technology has already been used in targeted deployment for prioritization of NG pipeline infrastructure repair and replacement, one open question regarding this technology is how effective the resulting data are for prioritizing infrastructure repair and replacement. To answer this question we explore the accuracy and precision of the natural gas leak location and emission estimates provided by methane sensors placed on Google Street View (GSV) vehicles. We find that the vast majority (75%) of methane emitting sources detected by these mobile platforms are NG leaks and that the location estimates are effective at identifying the general location of leaks. We also show that the emission rate estimates from mobile detection platforms are able to effectively rank NG leaks for prioritizing leak repair. Our findings establish that mobile sensing platforms are an efficient and effective tool for improving the safety and reducing the environmental impacts of low-pressure NG distribution systems by reducing atmospheric methane emissions.

The ISS 2B PVTCS Ammonia Leak: An Operational History

NASA Technical Reports Server (NTRS)

Vareha, Anthony

2014-01-01

In 2006, the Photovoltaic Thermal Control System (PVTCS) for the International Space Station's 2B power channel began leaking ammonia at a rate of approximately 1.5lbm/year (out of a starting approximately 53lbm system ammonia mass). Initially, the operations strategy was "feed the leak," a strategy successfully put into action via Extra Vehicular Activity during the STS-134 mission. During this mission the system was topped off with ammonia piped over from a separate thermal control system. This recharge was to have allowed for continued power channel operation into 2014 or 2015, at which point another EVA would have been required. Without these periodic EVAs to refill the 2B coolant system, the channel would eventually leak enough fluid as to risk pump cavitation and system failure, resulting in the loss of the 2B power channel - the most critical of the Space Station's 8 power channels. In mid-2012, the leak rate increased to approximately 5lbm/year. Once discovered, an EVA was planned and executed within a 5 week timeframe to drastically alter the architecture of the PVTCS via connection to a dormant thermal control system not intended to be utilized as anything other than spare components. The purpose of this rerouting of the TCS was to increase system volume and to isolate the photovoltaic radiator, thought to be the likely leak source. This EVA was successfully executed on November 1st, 2012 and left the 2B PVTCS in a configuration where the system was now being adequately cooled via a totally different radiator than what the system was designed to utilize. Unfortunately, data monitoring over the next several months showed that the isolated radiator was not leaking, and the system itself continued to leak steadily until May 9th, 2013. It was on this day that the ISS crew noticed the visible presence of ammonia crystals escaping from the 2B channel's truss segment, signifying a rapid acceleration of the leak from 5lbm/year to 5lbm/day. Within 48 hours of the

Sensitivity and specificity of intrathecal fluorescein and white light excitation for detecting intraoperative cerebrospinal fluid leak in endoscopic skull base surgery: a prospective study.

PubMed

Raza, Shaan M; Banu, Matei A; Donaldson, Angela; Patel, Kunal S; Anand, Vijay K; Schwartz, Theodore H

2016-03-01

The intraoperative detection of CSF leaks during endonasal endoscopic skull base surgery is critical to preventing postoperative CSF leaks. Intrathecal fluorescein (ITF) has been used at varying doses to aid in the detection of intraoperative CSF leaks. However, the sensitivity and specificity of ITF at certain dosages is unknown. A prospective database of all endoscopic endonasal procedures was reviewed. All patients received 25 mg ITF diluted in 10 ml CSF and were pretreated with dexamethasone and Benadryl. Immediately after surgery, the operating surgeon prospectively noted if there was an intraoperative CSF leak and fluorescein was identified. The sensitivity, specificity, and positive and negative predictive power of ITF for detecting intraoperative CSF leak were calculated. Factors correlating with postoperative CSF leak were determined. Of 419 patients, 35.8% of patients did not show a CSF leak. Fluorescein-tinted CSF (true positive) was noted in 59.7% of patients and 0 false positives were encountered. CSF without fluorescein staining (false negative) was noted in 4.5% of patients. The sensitivity and specificity of ITF were 92.9% and 100%, respectively. The negative and positive predictive values were 88.8% and 100%, respectively. Postoperative CSF leaks only occurred in true positives at a rate of 2.8%. ITF is extremely specific and very sensitive for detecting intraoperative CSF leaks. Although false negatives can occur, these patients do not appear to be at risk for postoperative CSF leak. The use of ITF may help surgeons prevent postoperative CSF leaks by intraoperatively detecting and confirming a watertight repair.

Long-life leak standard assembly

DOEpatents

Basford, James A.; Mathis, John E.; Wright, Harlan C.

1982-01-01

The present invention is directed to a portable leak standard assembly which is capable of providing a stream of high-purity reference gas at a virtually constant flow rate over an extensive period of time. The leak assembly comprises a high pressure reservoir coupled to a metal leak valve through a valve-controlled conduit. A reproducible leak valve useful in this assembly is provided by a metal tube crimped with a selected pressure loading for forming an orifice in the tube with this orifice being of a sufficient size to provide the selected flow rate. The leak valve assembly is formed of metal so that it can be "baked-out" in a vacuum furnace to rid the reservoir and attendent components of volatile impurities which reduce the efficiency of the leak standard.

Leakage detection in galvanized iron pipelines using ensemble empirical mode decomposition analysis

NASA Astrophysics Data System (ADS)

Amin, Makeen; Ghazali, M. Fairusham

2015-05-01

There are many numbers of possible approaches to detect leaks. Some leaks are simply noticeable when the liquids or water appears on the surface. However many leaks do not find their way to the surface and the existence has to be check by analysis of fluid flow in the pipeline. The first step is to determine the approximate position of leak. This can be done by isolate the sections of the mains in turn and noting which section causes a drop in the flow. Next approach is by using sensor to locate leaks. This approach are involves strain gauge pressure transducers and piezoelectric sensor. the occurrence of leaks and know its exact location in the pipeline by using specific method which are Acoustic leak detection method and transient method. The objective is to utilize the signal processing technique in order to analyse leaking in the pipeline. With this, an EEMD method will be applied as the analysis method to collect and analyse the data.

GPR image analysis to locate water leaks from buried pipes by applying variance filters

NASA Astrophysics Data System (ADS)

Ocaña-Levario, Silvia J.; Carreño-Alvarado, Elizabeth P.; Ayala-Cabrera, David; Izquierdo, Joaquín

2018-05-01

Nowadays, there is growing interest in controlling and reducing the amount of water lost through leakage in water supply systems (WSSs). Leakage is, in fact, one of the biggest problems faced by the managers of these utilities. This work addresses the problem of leakage in WSSs by using GPR (Ground Penetrating Radar) as a non-destructive method. The main objective is to identify and extract features from GPR images such as leaks and components in a controlled laboratory condition by a methodology based on second order statistical parameters and, using the obtained features, to create 3D models that allows quick visualization of components and leaks in WSSs from GPR image analysis and subsequent interpretation. This methodology has been used before in other fields and provided promising results. The results obtained with the proposed methodology are presented, analyzed, interpreted and compared with the results obtained by using a well-established multi-agent based methodology. These results show that the variance filter is capable of highlighting the characteristics of components and anomalies, in an intuitive manner, which can be identified by non-highly qualified personnel, using the 3D models we develop. This research intends to pave the way towards future intelligent detection systems that enable the automatic detection of leaks in WSSs.

Negative-pressure and low-pressure hydrocephalus: the role of cerebrospinal fluid leaks resulting from surgical approaches to the cranial base.

PubMed

Filippidis, Aristotelis S; Kalani, M Yashar S; Nakaji, Peter; Rekate, Harold L

2011-11-01

Negative-pressure and low-pressure hydrocephalus are rare clinical entities that are frequently misdiagnosed. They are characterized by recurrent episodes of shunt failure because the intracranial pressure is lower than the opening pressure of the valve. In this report the authors discuss iatrogenic CSF leaks as a cause of low- or negative-pressure hydrocephalus after approaches to the cranial base. The authors retrospectively reviewed cases of low-pressure or negative-pressure hydrocephalus presenting after cranial approaches complicated with a CSF leak at their institution. Three patients were identified. Symptoms of high intracranial pressure and ventriculomegaly were present, although the measured pressures were low or negative. A blocked communication between the ventricles and the subarachnoid space was documented in 2 of the cases and presumed in the third. Shunt revisions failed repeatedly. In all cases, temporary clinical and radiographic improvement resulted from external ventricular drainage at subatmospheric pressures. The CSF leaks were sealed and CSF communication was reestablished operatively. In 1 case, neck wrapping was used with temporary success. Negative-pressure or low-pressure hydrocephalus associated with CSF leaks, especially after cranial base approaches, is difficult to treat. The solution often requires the utilization of subatmospheric external ventricular drains to establish a lower ventricular drainage pressure than the drainage pressure created in the subarachnoid space, where the pressure is artificially lowered by the CSF leak. Treatment involves correction of the CSF leak, neck wrapping to increase brain turgor and allow the pressure in the ventricles to rise to the level of the opening pressure of the valve, and reestablishing the CSF route.

Improved Portable Ultrasonic Leak Detectors

NASA Technical Reports Server (NTRS)

Youngquist, Robert C.; Moerk, John S.; Haskell, William D.; Cox, Robert B.; Polk, Jimmy D.; Strobel, James P.; Luaces, Frank

1995-01-01

Improved portable ultrasonic leak detector features three interchangeable ultrasonic-transducer modules, each suited for operation in unique noncontact or contact mode. One module equipped with ultrasound-collecting horn for use in scanning to detect leaks from distance; horn provides directional sensitivity pattern with sensitivity multiplied by factor of about 6 in forward direction. Another module similar, does not include horn; this module used for scanning close to suspected leak, where proximity of leak more than offsets loss of sensitivity occasioned by lack of horn. Third module designed to be pressed against leaking vessel; includes rugged stainless-steel shell. Improved detectors perform significantly better, smaller, more rugged, and greater sensitivity.

Fuel leak detection apparatus for gas cooled nuclear reactors

DOEpatents

Burnette, Richard D.

1977-01-01

Apparatus is disclosed for detecting nuclear fuel leaks within nuclear power system reactors, such as high temperature gas cooled reactors. The apparatus includes a probe assembly that is inserted into the high temperature reactor coolant gaseous stream. The probe has an aperture adapted to communicate gaseous fluid between its inside and outside surfaces and also contains an inner tube for sampling gaseous fluid present near the aperture. A high pressure supply of noncontaminated gas is provided to selectively balance the pressure of the stream being sampled to prevent gas from entering the probe through the aperture. The apparatus includes valves that are operable to cause various directional flows and pressures, which valves are located outside of the reactor walls to permit maintenance work and the like to be performed without shutting down the reactor.

Superfluid helium leak sealant study

NASA Technical Reports Server (NTRS)

Vorreiter, J. W.

1981-01-01

Twenty-one leak specimens were fabricated in the ends of stainless steel and aluminum tubes. Eighteen of these tubes were coated with a copolymer material to seal the leak. The other three specimens were left uncoated and served as control specimens. All 21 tubes were cold shocked in liquid helium 50 times and then the leak rate was measured while the tubes were submerged in superfluid helium at 1.7 K. During the cold shocks two of the coated specimens were mechanically damaged and eliminated from the test program. Of the remaining 16 coated specimens one suffered a total coating failure and resulting high leak rate. Another three of the coated specimens suffered partial coating failures. The leak rates of the uncoated specimens were also measured and reported. The significance of various leak rates is discussed in view of the infrared astronomical satellite (IRAS) Dewar performance.

Demonstration of rapid and sensitive module leak certification for space station freedom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dietz, R.N.; Goodrich, R.W.

1991-03-01

A leak detection and quantification demonstration using perflurocarbon tracer (PFT) technology was successfully performed at the NASA Marshall Space Flight Center on January 25, 1991. The real-time Dual Trap Analyzer (DTA) at one-half hour after the start of the first run gave an estimated leak rate of 0.7 mL/min. This has since been refined to be 1.15 {plus minus} 0.09 mL/min. The leak rates in the next three runs were determined to be 9.8 {plus minus} 0.7, {minus}0.4 {plus minus} 0.3, and 76 {plus minus} 6 mL/min, respectively. The theory on leak quantification in the steady-state and time-dependent modes formore » a single zone test facility was developed and applied to the above determinations. The laboratory PFT analysis system gave a limit-of-detection (LOD) of 0.05 fL for ocPDCH. This is the tracer of choice and is about 100-fold better than that for the DTA. Applied to leak certification, the LOD is about 0.00002 mL/s (0.000075 L/h), a 5 order-of-magnitude improvement over the original leak certification specification. Furthermore, this limit can be attained in a measurement period of 3 to 4 hours instead of days, weeks, or months. A new Leak Certification Facility is also proposed to provide for zonal (three zones) determination of leak rates. The appropriate multizone equations, their solutions, and error analysis have already been derived. A new concept of seal-integrity certification has been demonstrated for a variety of controlled leaks in the range of module leak testing. High structural integrity leaks were shown to have a linear dependence of flow on {Delta}p. The rapid determination of leak rates at different pressures is proposed and is to be determined while subjecting the module to other external force-generating parameters such as vibration, torque, solar intensity, etc. 13 refs.« less

Demonstration of rapid and sensitive module leak certification for Space Station Freedom

NASA Technical Reports Server (NTRS)

Dietz, R. N.; Goodrich, R. W.

1991-01-01

A leak detection and quantification demonstration using perflurocarbon tracer (PFT) technology was successfully performed at the NASA Marshall Space Flight Center on January 25, 1991. The real-time Dual Trap Analyzer (DTA) at one-half hour after the start of the first run gave an estimated leak rate of 0.7 mL/min. This has since been refined to be 1.15 (+ or -) 0.09 mL/min. The leak rates in the next three runs were determined to be 9.8 (+ or -) 0.7, -0.4 (+ or -) 0.3, and 76 (+ or -) 6 mL/min, respectively. The theory on leak quantification in the steady-state and time-dependent modes for a single zone test facility was developed and applied to the above determinations. The laboratory PFT analysis system gave a limit-of-detection (LOD) of 0.05 fL for ocPDCH. This is the tracer of choice and is about 100-fold better than that for the DTA. Applied to leak certification, the LOD is about 0.00002 mL/s (0.000075 L/h), a 5 order-of-magnitude improvement over the original leak certification specification. Furthermore, this limit can be attained in a measurement period of 3 to 4 hours instead of days, weeks, or months. A new Leak Certification Facility is also proposed to provide for zonal (three zones) determination of leak rates. The appropriate multizone equations, their solutions, and error analysis have already been derived. A new concept of seal-integrity certification has been demonstrated for a variety of controlled leaks in the range of module leak testing. High structural integrity leaks were shown to have a linear dependence of flow on (Delta)p. The rapid determination of leak rates at different pressures is proposed and is to be determined while subjecting the module to other external force-generating parameters such as vibration, torque, solar intensity, etc.

Determinants of Unintentional Leaks During CPAP Treatment in OSA.

PubMed

Lebret, Marius; Arnol, Nathalie; Martinot, Jean-Benoît; Lambert, Loïc; Tamisier, Renaud; Pepin, Jean-Louis; Borel, Jean-Christian

2018-04-01

Unintentional leakage from the mouth or around the mask may lead to cessation of CPAP treatment; however, the causes of unintentional leaks are poorly understood. The objectives of this study were (1) to identify determining factors of unintentional leakage and (2) to determine the effect of the type of mask (nasal/oronasal) used on unintentional leakage. Seventy-four polysomnograms from patients with OSA syndrome treated with auto-CPAP were analyzed (23 women; 56 ± 13 years; BMI, 32.9 kg/m 2 (range, 29.0-38.0 kg/m 2 ). Polysomnographic recordings were obtained under auto-CPAP, and mandibular behavior was measured with a magnetic sensor. After sleep and respiratory scoring, polysomnographic signals were computed as mean values over nonoverlapping 10-s intervals. The presence/absence of unintentional leakage was dichotomized for each 10-s interval (yes/no). Univariate and multivariate conditional regression models estimated the risk of unintentional leaks during an interval "T" based on the explanatory variables from the previous interval "T-1." A sensitivity analysis for the type of mask was then conducted. The univariate analysis showed that mandibular lowering (mouth opening), a high level of CPAP, body position (other than supine), and rapid eye movement (REM) sleep increased the risk of unintentional leaks and microarousal decreased it. In the multivariate analysis, the same variables remained independently associated with an increased risk of unintentional leakage. The sensitivity analysis showed that oronasal masks reduced the risk of unintentional leaks in cases of mouth opening and REM sleep. Mouth opening, CPAP level, sleep position, and REM sleep independently contribute to unintentional leakage. These results provide a strong rationale for the definition of phenotypes and the individual management of leaks during CPAP treatment. Copyright © 2017 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

Present-day stress magnitude at depth from leak-off tests in Italy

NASA Astrophysics Data System (ADS)

Mariucci, M. T.; Montone, P.; Pierdominici, S.

2012-04-01

We present new results from the analysis of leak-off tests, performed in deep oil wells in Italy, to characterize the present-day stress magnitude and regime in the crust. In the last years we have collected a large number of data (more than 500) from different stress indicators, mainly borehole breakouts, earthquake focal mechanisms and fault data, which provided information on the present-day stress orientations. In some areas the tectonic regime has been inferred either from fault plane solutions of M≥4 earthquakes or from stress inversions of smaller earthquakes. Where seismicity lacks, the regime is not well constrained and little or no information on the magnitude of the crustal stresses is available. In order to improve our knowledge in stress regime and its magnitude in Italy, in this work we use the leak-off test technique. Each test is performed at the bottom of an open hole by sealing off a section and then slowly pressurizing with a fluid until hydraulic tensile fractures develop. The minimum horizontal stress is inferred by leak-off pressure record, the vertical stress is computed by rock density data and the maximum horizontal stress is estimated applying a specific formula from the literature. Thanks to ENI S.p.A. (Italian oil company), that kindly provided new well data, we have been able to perform a critical review of our preliminary calculations and to enhance our previous results concerning stress magnitudes. Totally, we have analyzed 192 leak-off tests at depth between 200 and 5400m (average 1800m). In particular, wells are located along the Italian peninsula and in Sicily: most of them are in the Po Plain and along the Apenninic foredeep; few are in southern Apenninic belt and a few tens are in Sicily. After an accurate selection of the most robust results, we better characterize the Italian stress regime at depth.

Spontaneous spinal cerebrospinal fluid leak as a cause of coma after craniotomy for clipping of an unruptured intracranial aneurysm.

PubMed

Schievink, Wouter I; Palestrant, David; Maya, M Marcel; Rappard, George

2009-03-01

Spontaneous spinal CSF leaks are best known as a cause of orthostatic headache, but may also be the cause of coma. The authors encountered a unique case of a spontaneous spinal CSF leak causing coma 2 days after craniotomy for clipping of an unruptured aneurysm. This 44-year-old woman with autosomal dominant polycystic kidney disease underwent an uneventful craniotomy for an incidental anterior choroidal artery aneurysm. No intraoperative spinal CSF drainage was used. Two days after surgery the patient became comatose with a left oculomotor nerve palsy. Computed tomography scanning revealed a right extraceberal hematoma and loss of gray-white matter differentiation. The hematoma was evacuated and a diagnosis of hemodialysis disequilibrium syndrome was made. Continuous hemodialysis and hyperosmolar therapy were instituted without any improvement. The CT scans were then reinterpreted as showing sagging of the brain, and the patient was placed in the Trendelenburg position which resulted in prompt improvement in her level of consciousness. A CT myelogram demonstrated an upper thoracic CSF leak that eventually required surgical correction. The patient made a complete neurological recovery. Neurological deterioration after craniotomy may be caused by brain sagging caused by a spontaneous spinal CSF leak, similar to intracranial hypotension due to intraoperative lumbar CSF drainage.

14 CFR 25.1183 - Flammable fluid-carrying components.

Code of Federal Regulations, 2012 CFR

2012-01-01

... safeguard against the ignition of leaking flammable fluid. An integral oil sump of less than 25-quart..., essential services or equipment. [Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-11, 32...

14 CFR 25.1183 - Flammable fluid-carrying components.

Code of Federal Regulations, 2011 CFR

2011-01-01

... safeguard against the ignition of leaking flammable fluid. An integral oil sump of less than 25-quart..., essential services or equipment. [Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-11, 32...

14 CFR 25.1183 - Flammable fluid-carrying components.

Code of Federal Regulations, 2010 CFR

2010-01-01

... safeguard against the ignition of leaking flammable fluid. An integral oil sump of less than 25-quart..., essential services or equipment. [Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-11, 32...

14 CFR 25.1183 - Flammable fluid-carrying components.

Code of Federal Regulations, 2013 CFR

2013-01-01

... safeguard against the ignition of leaking flammable fluid. An integral oil sump of less than 25-quart..., essential services or equipment. [Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-11, 32...

Single cell rheometry with a microfluidic constriction: Quantitative control of friction and fluid leaks between cell and channel walls

PubMed Central

Preira, Pascal; Valignat, Marie-Pierre; Bico, José; Théodoly, Olivier

2013-01-01

We report how cell rheology measurements can be performed by monitoring the deformation of a cell in a microfluidic constriction, provided that friction and fluid leaks effects between the cell and the walls of the microchannels are correctly taken into account. Indeed, the mismatch between the rounded shapes of cells and the angular cross-section of standard microfluidic channels hampers efficient obstruction of the channel by an incoming cell. Moreover, friction forces between a cell and channels walls have never been characterized. Both effects impede a quantitative determination of forces experienced by cells in a constriction. Our study is based on a new microfluidic device composed of two successive constrictions, combined with optical interference microscopy measurements to characterize the contact zone between the cell and the walls of the channel. A cell squeezed in a first constriction obstructs most of the channel cross-section, which strongly limits leaks around cells. The rheological properties of the cell are subsequently probed during its entry in a second narrower constriction. The pressure force is determined from the pressure drop across the device, the cell velocity, and the width of the gutters formed between the cell and the corners of the channel. The additional friction force, which has never been analyzed for moving and constrained cells before, is found to involve both hydrodynamic lubrication and surface forces. This friction results in the existence of a threshold for moving the cells and leads to a non-linear behavior at low velocity. The friction force can nevertheless be assessed in the linear regime. Finally, an apparent viscosity of single cells can be estimated from a numerical prediction of the viscous dissipation induced by a small step in the channel. A preliminary application of our method yields an apparent loss modulus on the order of 100 Pa s for leukocytes THP-1 cells, in agreement with the literature data. PMID:24404016

Prolonged air leak following lobectomy can be predicted in lung cancer patients.

PubMed

Okada, Satoru; Shimada, Junichi; Kato, Daishiro; Tsunezuka, Hiroaki; Inoue, Masayoshi

2017-08-01

The purpose of this study was to identify the factors associated with prolonged air leak (PAL) following pulmonary lobectomy for lung cancer. The data of 146 patients who underwent pulmonary lobectomy for lung cancer between August 2010 and July 2015 were retrospectively reviewed. Air leaks were assessed daily by a visual evaluation and were categorized as follows: forced expiratory only (Grade 1), expiratory only (Grade 2), or continuous (Grade 3). Logistic regression analyses were performed to identify the predictors of PAL (>5 days). PAL occurred in 23 patients (16%). An air leak at rest (Grade ≥ 2) was detected on postoperative day (POD) 1 in 48% of the patients with PAL and 7% of the patients without PAL. A univariate analysis demonstrated that PAL was significantly associated with male sex, a smoking history of ≥ 40 pack years, a serum albumin level of ≤4.0 mg/dL, and an air leak on POD1 (Grade ≥ 2). A multivariate analysis demonstrated that a serum albumin level of ≤4.0 mg/dL (p = 0.027) and an air leak on POD1 (p = 0.006) were independent predictors of PAL. PAL occurred in 75% of the patients with these two risk factors. The preoperative serum albumin level and the presence of a visually evaluated air leak on POD1 may be useful indicators for the perioperative management of air leaks.

Drain Tube-Induced Jejunal Penetration Masquerading as Bile Leak following Whipple's Operation.

PubMed

Bae, Sang Ho; Lee, Tae Hoon; Lee, Sae Hwan; Lee, Suck-Ho; Park, Sang-Heum; Kim, Sun-Joo; Kim, Chang Ho

2011-05-01

A 70-year-old man had undergone pancreaticoduodenectomy due to a distal common bile duct malignancy. After the operation, serous fluid discharge decreased from two drain tubes in the retroperitoneum. Over four weeks, the appearance of the serous fluid changed to a greenish bile color and the patient persistently drained over 300 ml/day. Viewed as bile leak at the choledochojejunostomy, treatment called for endoscopic diagnosis and therapy. Cap-fitted forward-viewing endoscopy demonstrated that the distal tip of a pancreatic drain catheter inserted at the pancreaticojejunostomy site had penetrated the opposite jejunum wall. One of the drain tubes primarily placed in the retroperitoneum had also penetrated the jejunum wall, with the distal tip positioned near the choledochojejunostomy site. No leak of contrast appeared beyond the jejunum or anastomosis site. Following repositioning of a penetrating catheter of the pancreaticojejunostomy, four days later, the patient underwent removal of two drain tubes without additional complications. In conclusion, the distal tip of the catheter, placed to drain pancreatic juice, penetrated the jejunum wall and may have caused localized perijejunal inflammation. The other drain tube, placed in the retroperitoneal space, might then have penetrated the inflamed wall of the jejunum, allowing persistent bile drainage via the drain tube. The results masqueraded as bile leakage following pancreaticoduodenectomy.

Chest tube management following pulmonary lobectomy: change of protocol results in fewer air leaks.

PubMed

Bertholet, Joost W M; Joosten, Joris J A; Keemers-Gels, Mariël E; van den Wildenberg, Frits J H; Barendregt, Wouter B

2011-01-01

Much controversy exists regarding the management of chest tubes following pulmonary lobectomy. The objective of this study was to analyse the effect of a new chest tube management protocol on clinical features, such as postoperative air leak, drain characteristics, 30-day postoperative complications and length of hospital stay. We retrospectively analysed 133 patients who underwent pulmonary lobectomy, from January 2005 to December 2008. A new chest tube protocol was introduced on 1 January 2007 and included placement of a single chest tube and early conversion to water seal. The chest tube was removed when air leak had resolved and (non-chylous) fluid drainage was <400 ml/day. The results of patients in the old (n=68) and the new protocol (n=65) were compared. In the new protocol group the median duration of air leak and duration of chest tube drainage declined significantly. Also the length of hospital stay decreased significantly to a median of eight days. The number of reinterventions and 30-day morbidity and mortality rates did not differ significantly. Our data suggest that placement of a single chest tube and early conversion to water seal decreases the duration of air leak and chest tube drainage and length of hospital stay.

Leak rate measurements for satellite subsystems and residual gas analysis during space environment tests. [thermal vacuum and solar simulation tests

NASA Technical Reports Server (NTRS)

Nuss, H. E.

1975-01-01

The measuring and evaluation procedure for the determination of leak rates of satellite subsystems with a quadrupole mass spectrometer, and the results of the residual gas analysis are described. The method selected for leak rate determination was placing the system into a vacuum chamber and furnishing the chamber with a mass spectrometer and calibrated leaks. The residual gas of a thermal vacuum test facility, in which the thermal balance test radiation input was simulated by a heated canister, was analyzed with the mass spectrometer in the atomic mass unit range up to 300 amu. In addition to the measurements during the space environment tests, mass spectrometric studies were performed with samples of spacecraft materials. The studies were carried out during tests for the projects HELIOS, AEROS B and SYMPHONIE.

Hermetic Seal Leak Detection Apparatus

NASA Technical Reports Server (NTRS)

Kelley, Anthony R. (Inventor)

2013-01-01

The present invention is a hermetic seal leak detection apparatus, which can be used to test for hermetic seal leaks in instruments and containers. A vacuum tight chamber is created around the unit being tested to minimize gas space outside of the hermetic seal. A vacuum inducing device is then used to increase the gas chamber volume inside the device, so that a slight vacuum is pulled on the unit being tested. The pressure in the unit being tested will stabilize. If the stabilized pressure reads close to a known good seal calibration, there is not a leak in the seal. If the stabilized pressure reads closer to a known bad seal calibration value, there is a leak in the seal. The speed of the plunger can be varied and by evaluating the resulting pressure change rates and final values, the leak rate/size can be accurately calculated.

Paravalvular Leak in Structural Heart Disease.

PubMed

Goel, Kashish; Eleid, Mackram F

2018-03-06

This review will summarize the growing importance of diagnosing and managing paravalvular leak associated with surgical and transcatheter valves. The burden of paravalvular leak is increasing; however, advanced imaging techniques and high degree of clinical suspicion are required for diagnosis and management. The latest data from pivotal clinical trials in the field of transcatheter aortic valve replacement suggest that any paravalvular leak greater than mild was associated with worse clinical outcomes. Percutaneous techniques for paravalvular leak closure are now the preferred approach, and surgical repair is reserved for contraindications and unsuccessful procedures. Recent data from studies evaluating paravalvular leak closure outcomes report a greater than 90% success rate with a significant improvement in patient symptoms. Paravalvular leak is a growing problem in the structural heart disease arena. Percutaneous closure is successful in more than 90% of the procedures with a low complication rate.

Fluids and sepsis: changing the paradigm of fluid therapy: a case report.

PubMed

Hariyanto, Hori; Yahya, Corry Quando; Widiastuti, Monika; Wibowo, Primartanto; Tampubolon, Oloan Eduard

2017-02-04

Over the past 16 years, sepsis management has been guided by large-volume fluid administration to achieve certain hemodynamic optimization as advocated in the Rivers protocol. However, the safety of such practice has been questioned because large-volume fluid administration is associated with fluid overload and carries the worst outcome in patients with sepsis. Researchers in multiple studies have declared that using less fluid leads to increased survival, but they did not describe how to administer fluids in a timely and appropriate manner. An 86-year-old previously healthy Sundanese man was admitted to the intensive care unit at our institution with septic shock, acute kidney injury, and respiratory distress. Standard care was implemented during his initial care in the high-care unit; nevertheless, his condition worsened, and he was transferred to the intensive care unit. We describe the timing of fluid administration and elaborate on the amount of fluids needed using a conservative fluid regimen in a continuum of resuscitated sepsis. Because fluid depletion in septic shock is caused by capillary leak and pathologic vasoplegia, continuation of fluid administration will drive intravascular fluid into the interstitial space, thereby producing marked tissue edema and disrupting vital oxygenation. Thus, fluids have the power to heal or kill. Therefore, management of patients with sepsis should entail early vasopressors with adequate fluid resuscitation followed by a conservative fluid regimen.

Traumatic orbital CSF leak

PubMed Central

Borumandi, Farzad

2013-01-01

Compared to the cerebrospinalfluid (CSF) leak through the nose and ear, the orbital CSF leak is a rare and underreported condition following head trauma. We present the case of a 49-year-old woman with oedematous eyelid swelling and ecchymosis after a seemingly trivial fall onto the right orbit. Apart from the above, she was clinically unremarkable. The CT scan revealed a minimally displaced fracture of the orbital roof with no emphysema or intracranial bleeding. The fractured orbital roof in combination with the oedematous eyelid swelling raised the suspicion for orbital CSF leak. The MRI of the neurocranium demonstrated a small-sized CSF fistula extending from the anterior cranial fossa to the right orbit. The patient was treated conservatively and the lid swelling resolved completely after 5 days. Although rare, orbital CSF leak needs to be included in the differential diagnosis of periorbital swelling following orbital trauma. PMID:24323381

Blind Leak Detection for Closed Systems

NASA Technical Reports Server (NTRS)

Oelgoetz, Peter; Johnson, Ricky; Todd, Douglas; Russell, Samuel; Walker, James

2003-01-01

The current inspection technique for locating interstitial leaking in the Space Shuttle Main Engine nozzles is the application of a liquid leak check solution in the openings where the interstitials space between the tubing and the structural jacket vent out the aft end of the nozzle, while its cooling tubes are pressurized to 25 psig with Helium. When a leak is found, it is classified, and if the leak is severe enough the suspect tube is cut open so that a boroscope can be inserted to find the leak point. Since the boroscope can only cover a finite tube length and since it is impossible to identify which tube (to the right or left of the identified interstitial) is leaking, many extra and undesired repairs have been made to fix just one leak. In certain instances when the interstitials are interlinked by poor braze bonding, many interstitials will show indications of leaking from a single source. What is desired is a technique that can identify the leak source so that a single repair can be performed. Dr, Samuel Russell and James Walker, both with NASA/MSFC have developed a thermographic inspection system that addresses a single repair approach. They have teamed with Boeing/Rocketdyne to repackage the inspection processes to be suitable to address full scale Shuttle development and flight hardware and implement the process at NASA centers. The methods and results presented address the thermographic identification of interstitial leaks in the Space Shuttle Main Engine nozzles. A highly sensitive digital infrared camera (capable of detecting a delta temperature difference of 0.025 C) is used to record the cooling effects associated with a leak source, such as a crack or pinhole, hidden within the nozzle wall by observing the inner hot wall surface as the nozzle is pressurized, These images are enhanced by digitally subtracting a thermal reference image taken before pressurization. The method provides a non-intrusive way of locating the tube that is leaking and the

The Sixth Annual Thermal and Fluids Analysis Workshop

NASA Technical Reports Server (NTRS)

1995-01-01

The Sixth Annual Thermal and Fluids Analysis Workshop consisted of classes, vendor demonstrations, and paper sessions. The classes and vendor demonstrations provided participants with the information on widely used tools for thermal and fluids analysis. The paper sessions provided a forum for the exchange of information and ideas among thermal and fluids analysis. Paper topics included advances an uses of established thermal and fluids computer codes (such as SINDA and TRASYS) as well as unique modeling techniques and applications.

Technical factors associated with anastomotic leak after Roux-en-Y gastric bypass.

PubMed

Smith, Mark D; Adeniji, Abidemi; Wahed, Abdus S; Patterson, Emma; Chapman, William; Courcoulas, Anita P; Dakin, Gregory; Flum, David; McCloskey, Carol; Mitchell, James E; Pomp, Alfons; Staten, Myrlene; Wolfe, Bruce

2015-01-01

Anastomotic leak is one of the most serious complications after Roux-en-Y gastric bypass (RYGB). Our objective was to examine the relationship between technical factors and incidence of clinically relevant anastomotic leak after RYGB in longitudinal assessment of bariatric surgery (LABS). The setting of the study was 11 bariatric centers in the United States, university, and private practice. Patient characteristics, technical factors of surgery, and postoperative outcomes were assessed by trained researchers using standardized protocols. Correlation of surgical factors of patients undergoing RYGB (n = 4444) with the incidence of postoperative anastomotic leak was assessed by univariate χ(2) analysis. Forty-four participants (1.0%, 95% CI .7%-1.3%) experienced a clinically relevant anastomotic leak. Of these, 39 (89%) underwent abdominal reoperation and 3 (7%) died. Technical factors associated with anastomotic leak were open surgery (P<.0001), revision surgery (P<.0001), and use of an abdominal drain (P = .02). Provocative leak testing, method of gastrojejunostomy, and use of fibrin sealant were not associated with anastomotic leak. Anastomotic leak after RYGB was rare (1.0%). Most cases required reintervention; however, the majority (93%) recovered from this event. Open surgery, revision surgery, and routine drain placement were associated with increased leak rate. Some of these findings may be due to differences in preoperative patient risk. Copyright © 2015 American Society for Metabolic and Bariatric Surgery. All rights reserved.

Leak Isolation in Pressurized Pipelines using an Interpolation Function to approximate the Fitting Losses

NASA Astrophysics Data System (ADS)

Badillo-Olvera, A.; Begovich, O.; Peréz-González, A.

2017-01-01

The present paper is motivated by the purpose of detection and isolation of a single leak considering the Fault Model Approach (FMA) focused on pipelines with changes in their geometry. These changes generate a different pressure drop that those produced by the friction, this phenomenon is a common scenario in real pipeline systems. The problem arises, since the dynamical model of the fluid in a pipeline only considers straight geometries without fittings. In order to address this situation, several papers work with a virtual model of a pipeline that generates a equivalent straight length, thus, friction produced by the fittings is taking into account. However, when this method is applied, the leak is isolated in a virtual length, which for practical reasons does not represent a complete solution. This research proposes as a solution to the problem of leak isolation in a virtual length, the use of a polynomial interpolation function in order to approximate the conversion of the virtual position to a real-coordinates value. Experimental results in a real prototype are shown, concluding that the proposed methodology has a good performance.

Helium Mass Spectrometer Leak Detection: A Method to Quantify Total Measurement Uncertainty

NASA Technical Reports Server (NTRS)

Mather, Janice L.; Taylor, Shawn C.

2015-01-01

In applications where leak rates of components or systems are evaluated against a leak rate requirement, the uncertainty of the measured leak rate must be included in the reported result. However, in the helium mass spectrometer leak detection method, the sensitivity, or resolution, of the instrument is often the only component of the total measurement uncertainty noted when reporting results. To address this shortfall, a measurement uncertainty analysis method was developed that includes the leak detector unit's resolution, repeatability, hysteresis, and drift, along with the uncertainty associated with the calibration standard. In a step-wise process, the method identifies the bias and precision components of the calibration standard, the measurement correction factor (K-factor), and the leak detector unit. Together these individual contributions to error are combined and the total measurement uncertainty is determined using the root-sum-square method. It was found that the precision component contributes more to the total uncertainty than the bias component, but the bias component is not insignificant. For helium mass spectrometer leak rate tests where unit sensitivity alone is not enough, a thorough evaluation of the measurement uncertainty such as the one presented herein should be performed and reported along with the leak rate value.

Apparatus for detecting leaks

DOEpatents

Booth, Eugene T.

1976-02-24

A method and apparatus for determining the position of and estimating the size of leaks in an evacuating apparatus comprising the use of a testing gas such as helium or hydrogen flowing around said apparatus whereby the testing gas will be drawn in at the site of any leaks.

METHOD AND APPARATUS FOR THE DETECTION OF LEAKS IN PIPE LINES

DOEpatents

Jefferson, S.; Cameron, J.F.

1961-11-28

A method is described for detecting leaks in pipe lines carrying fluid. The steps include the following: injecting a radioactive solution into a fluid flowing in the line; flushing the line clear of the radioactive solution; introducing a detector-recorder unit, comprising a radioactivity radiation detector and a recorder which records the detector signal over a time period at a substantially constant speed, into the line in association with a go-devil capable of propelling the detector-recorder unit through the line in the direction of the fluid flow at a substantia1ly constant velocity; placing a series of sources of radioactivity at predetermined distances along the downstream part of the line to make a characteristic signal on the recorder record at intervals corresponding to the location of said sources; recovering the detector-recorder unit at a downstream point along the line; transcribing the recorder record of any radioactivity detected during the travel of the detector- recorder unit in terms of distance along the line. (AEC)

Gaseous leak detector

DOEpatents

Juravic, Jr., Frank E.

1988-01-01

In a short path length mass-spectrometer type of helium leak detector wherein the helium trace gas is ionized, accelerated and deflected onto a particle counter, an arrangement is provided for converting the detector to neon leak detection. The magnetic field of the deflection system is lowered so as to bring the non linear fringe area of the magnetic field across the ion path, thereby increasing the amount of deflection of the heavier neon ions.

Demonstration of rapid and sensitive module leak certification for space station freedom. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dietz, R.N.; Goodrich, R.W.

1991-03-01

A leak detection and quantification demonstration using perflurocarbon tracer (PFT) technology was successfully performed at the NASA Marshall Space Flight Center on January 25, 1991. The real-time Dual Trap Analyzer (DTA) at one-half hour after the start of the first run gave an estimated leak rate of 0.7 mL/min. This has since been refined to be 1.15 {plus_minus} 0.09 mL/min. The leak rates in the next three runs were determined to be 9.8 {plus_minus} 0.7, {minus}0.4 {plus_minus} 0.3, and 76 {plus_minus} 6 mL/min, respectively. The theory on leak quantification in the steady-state and time-dependent modes for a single zone testmore » facility was developed and applied to the above determinations. The laboratory PFT analysis system gave a limit-of-detection (LOD) of 0.05 fL for ocPDCH. This is the tracer of choice and is about 100-fold better than that for the DTA. Applied to leak certification, the LOD is about 0.00002 mL/s (0.000075 L/h), a 5 order-of-magnitude improvement over the original leak certification specification. Furthermore, this limit can be attained in a measurement period of 3 to 4 hours instead of days, weeks, or months. A new Leak Certification Facility is also proposed to provide for zonal (three zones) determination of leak rates. The appropriate multizone equations, their solutions, and error analysis have already been derived. A new concept of seal-integrity certification has been demonstrated for a variety of controlled leaks in the range of module leak testing. High structural integrity leaks were shown to have a linear dependence of flow on {Delta}p. The rapid determination of leak rates at different pressures is proposed and is to be determined while subjecting the module to other external force-generating parameters such as vibration, torque, solar intensity, etc. 13 refs.« less

Grading of Emphysema Is Indispensable for Predicting Prolonged Air Leak After Lung Lobectomy.

PubMed

Murakami, Junichi; Ueda, Kazuhiro; Tanaka, Toshiki; Kobayashi, Taiga; Hamano, Kimikazu

2018-04-01

The aim of this study was to assess the utility of quantitative computed tomography-based grading of emphysema for predicting prolonged air leak after thoracoscopic lobectomy. A consecutive series of 284 patients undergoing thoracoscopic lobectomy for lung cancer was retrospectively reviewed. Prolonged air leak was defined as air leaks lasting 7 days or longer. The grade of emphysema (emphysema index) was defined by the proportion of the emphysematous lung volume (less than -910 HU) to the total lung volume (-600 to -1,024 HU) by a computer-assisted histogram analysis of whole-lung computed tomography scans. The mean length of chest tube drainage was 1.5 days. Fifteen patients (5.3%) presented with prolonged air leak. According to a receiver-operating characteristics curve analysis, the emphysema index was the best predictor of prolonged air leak, with an area under the curve of 0.85 (95% confidence interval: 0.73 to 0.98). An emphysema index of 35% or greater was the best cutoff value for predicting prolonged air leak, with a negative predictive value of 0.99. The emphysema index was the only significant predictor for the length of postoperative chest tube drainage among conventional variables, including the pulmonary function and resected lobe, in both univariate and multivariate analyses. Prolonged air leak resulted in an increased duration of hospitalization (p < 0.001) and was frequently accompanied by pneumonia or empyema (p < 0.001). The grade of emphysema on computed tomography scan is the best predictor of prolonged air leak that adversely influences early postoperative outcomes. We must take new measures against prolonged air leak in quantitative computed tomography-based high-risk patients. Copyright © 2018 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Leak detection with expandable coatings

NASA Technical Reports Server (NTRS)

1971-01-01

Developed and evaluated is a system for leak detection that can be easily applied over separable connectors and that expands into a bubble or balloon if a leak is present. This objective is accomplished by using thin films of Parafilm tape wrapped over connectors, which are then overcoated with a special formulation. The low yield strength and the high elongation of the envelope permit bubble formation if leakage occurs. This system is appropriate for welds and other hardware besides separable connectors. The practical limit of this system appears to be for leaks exceeding 0.000001 cc/sec. If this envelope is used to trap gases for mass spectrometer inspection, leaks in the range of ten to the minus 8th power cc/sec. may be detectable.

Experimental investigation of the effect orifice shape and fluid pressure has on high aspect ratio cross-sectional jet behaviour.

PubMed

Wakes, S J; Holdø, A E; Meares, A J

2002-01-04

Prevention of major disasters such as Piper Alpha is a concern of oil and gas companies when commissioning a new offshore superstructure. Safety studies are undertaken to identify potential major hazards, risks to personnel and that sufficient precautions have been employed to minimise these. Such an assessment will also include the consideration of the protection from gas leaks such as the optimum positions of gas leak detectors and startup safety procedures after a leak. This requires a comprehensive knowledge of the behaviour of the leaking hydrocarbons as they emerge from the leak into the area of concern. Such leaks are most likely to emanate from a high aspect ratio cross-sectional curved slot in a pipeline. This paper challenges the conventional view that it is sufficient to model such leaks as axisymmetric jets. This paper is therefore concerned with an experimental study carried out on a series of more realistic high aspect ratio cross-sectional jets issuing from a flange orifice. Both high quality photographs in both planes of the jets and some quantitative pressure data is examined for a high aspect ratio cross-sectional jet of air at pressures up to 4.136bar. The effect of changing aspect ratio, fluid pressure and orifice shape will be discussed and put into context with regard to how this relates to offshore analysis studies.

Leak testing and repair of fusion devices

NASA Astrophysics Data System (ADS)

Kozman, T. A.

1983-06-01

The leak testing, reporting and vacuum leak repair techniques of the MPTF yin-yang number one magnet system, the world's largest superconducting magnet system, are discussed. Based on this experience, techniques are developed for testing and repairing leaks on the 42 MPTF-B magnets. The leak hunting techniques for the yin-yang magnet systems were applied to two helium circuits (the coil bundle and guard vacuum; both require helium flow for magnet cooldown). Additionally, during MPTF-B operation there are warm water plasma shields and piping that require leak checking.

40 CFR 63.1005 - Leak repair.

Code of Federal Regulations, 2013 CFR

2013-07-01

... lubricant into the lubricated packing. (b) Leak identification removal—(1) Valves in gas/vapor and light liquid service. The leak identification on a valve in gas/vapor or light liquid service may be removed... monitoring. The leak identification on a connector in gas/vapor or light liquid service may be removed after...

40 CFR 63.1005 - Leak repair.

Code of Federal Regulations, 2012 CFR

2012-07-01

... lubricant into the lubricated packing. (b) Leak identification removal—(1) Valves in gas/vapor and light liquid service. The leak identification on a valve in gas/vapor or light liquid service may be removed... monitoring. The leak identification on a connector in gas/vapor or light liquid service may be removed after...

40 CFR 63.1005 - Leak repair.

Code of Federal Regulations, 2011 CFR

2011-07-01

... lubricant into the lubricated packing. (b) Leak identification removal—(1) Valves in gas/vapor and light liquid service. The leak identification on a valve in gas/vapor or light liquid service may be removed... monitoring. The leak identification on a connector in gas/vapor or light liquid service may be removed after...

40 CFR 63.1005 - Leak repair.

Code of Federal Regulations, 2014 CFR

2014-07-01

... lubricant into the lubricated packing. (b) Leak identification removal—(1) Valves in gas/vapor and light liquid service. The leak identification on a valve in gas/vapor or light liquid service may be removed... monitoring. The leak identification on a connector in gas/vapor or light liquid service may be removed after...

40 CFR 265.196 - Response to leaks or spills and disposition of leaking or unfit-for-use tank systems.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Response to leaks or spills and... leaks or spills and disposition of leaking or unfit-for-use tank systems. A tank system or secondary containment system from which there has been a leak or spill, or which is un-fit for use, must be removed from...

Analytical study of the performance of a geomembrane leak detection system.

PubMed

Lugli, Francesco; Mahler, Claudio Fernando

2016-05-01

The electrical detection of leaks in geomembranes is a method that allows identifying leakage of contaminants in lined facilities (e.g. sanitary landfills, pollutant ponds, etc.). The procedure in the field involves placing electrodes above and below the geomembrane, to generate an electrical current, which in turn engenders an electric potential distribution in the protective layer (generally a clayey soil). The electric potential will be greater in areas with higher current density, i.e. near leaks. In this study, we combined models from the literature to carry out a parametric analysis to identify the variables that most influence the amplitude of the electrical signals produced by leaks. The basic hypothesis is that the electrical conduction phenomena in a liner system could be depicted by a direct current circuit. After determining the value of the current at the leak, we calculated the electric potential distribution according to the model of Darilek and Laine. This enabled analysing the sensitivity of the parameters, which can be useful in the design of landfills and facilitate the location of leaks. This study showed that geomembranes with low electrical resistance (owing to low thickness, low resistivity, or extensive area) can hinder the leak detection process. In contrast, low thickness and high resistivity of the protection layer magnify the leak signal. © The Author(s) 2016.

Glycol leak detection system

NASA Astrophysics Data System (ADS)

Rabe, Paul; Browne, Keith; Brink, Janus; Coetzee, Christiaan J.

2016-07-01

MonoEthylene glycol coolant is used extensively on the Southern African Large Telescope to cool components inside the telescope chamber. To prevent coolant leaks from causing serious damage to electronics and optics, a Glycol Leak Detection System was designed to automatically shut off valves in affected areas. After two years of research and development the use of leaf wetness sensors proved to work best and is currently operational. These sensors are placed at various critical points within the instrument payload that would trigger the leak detector controller, which closes the valves, and alerts the building management system. In this paper we describe the research of an initial concept and the final accepted implementation and the test results thereof.

Skull Base Cerebrospinal Fluid Leakage Control with a Fibrin-Based Composite Tissue Adhesive

PubMed Central

Rock, Jack P.; Sierra, David H.; Castro-Moure, Frederico; Jiang, Feng

1996-01-01

Cerebrospinal fluid (CSF) leaks can be responsible for significant patient morbidity and mortality. While the majority of leaks induced after head trauma will seal without intervention, spontaneous or surgically-induced leaks often require operative repair. Many modifications on standard surgical technique are available for repair of CSF fistulae, but none assures adequate closure. We have studied the efficacy of a novel fibrin-based composite tissue adhesive (CTA) for closure of experimentally-induced CSF leaks in rats. Fistulae were created in two groups of animals. Two weeks after creation of the leaks, the animals were sacrificed and analyzed for persistence of leak. A 58% leakage rate was noted in the control group (n = 12), and no leaks were noted in the experimental group closed after application of CTA to the surgical defect followed by skin closure (n = 11). Comparing the control group to the experimental group, results were statistically significant (p = 0.015). These data suggest that CTA may be effective as an adjunct for the closure of CSF fistulae. ImagesFigure 2Figure 3 PMID:17170969

Influence of intraoperative hypotension on leaks after sleeve gastrectomy.

PubMed

Nienhuijs, Simon W; Kaymak, Uzay; Korsten, Erik; Buise, Marc P

2016-01-01

Leak after a sleeve gastrectomy (SG) is a severe complication. Risk factors, such as regional ischemia, increased intraluminal pressure, technical failure of the stapling device, and surgeon error, have been reported. It was hypothesized that intraoperative hypotension is another risk factor for leak, similar to that reported for colorectal surgery. Tertiary teaching hospital in The Netherlands. Results of a 7-year cohort of primary SGs were reviewed in relation to multiple intraoperative blood pressure measurements. The thresholds for the mean pressure were 40 to 70 mm Hg and for the systolic pressure 70 to 100 mm Hg. Only continuous episodes of 15 and 20 minutes were included. Twenty-four leaks were identified in a cohort of 1041 primary SGs. Episodes of systolic blood pressure<100 mm Hg for 15 min (P = .027) and 20 minutes (P = .008) were significantly related to a staple line leak. An episode of mean blood pressure<70 mm Hg for 20 min was significantly related to leak (P = .014). Episodes with lower thresholds of pressure occurred less frequently and revealed no significant differences. Other identified risk factors were smoking (P = .019), fast-track recovery program (P = .006), use of a tri-stapler (P = .004), and duration of surgery (P = .000). In a multivariate analysis, only intraoperative systolic pressure<100 mm Hg for 20 minutes remained significant (odds ratio, 2.45; P = .012). Intraoperative hypotension may contribute independently to a leak after SG. Copyright © 2016 American Society for Bariatric Surgery. Published by Elsevier Inc. All rights reserved.

Long-life leak standard assembly. [Patent application

DOEpatents

Basford, J.A.; Mathis, J.E.; Wright, H.C.

1980-11-12

The present invention is directed to a portable leak standard assembly which is capable of providing a stream of high-purity reference gas at a virtually constant flow rate over an extensive period of time. The leak assembly comprises a high pressure reservoir coupled to a metal leak valve through a valve-controlled conduit. A reproducible leak valve useful in this assembly is provided by a metal tube crimped with a selected pressure loading for forming an orifice in the tube with this orifice being of a sufficient size to provide the selected flow rate. The leak valve assembly is formed of metal so that it can be baked-out in a vacuum furnace to rid the reservoir and attendent components of volatile impurities which reduce the efficiency of the leak standard.

Annular Air Leaks in a liquid hydrogen storage tank

NASA Astrophysics Data System (ADS)

Krenn, AG; Youngquist, RC; Starr, SO

2017-12-01

Large liquid hydrogen (LH2) storage tanks are vital infrastructure for NASA, the DOD, and industrial users. Over time, air may leak into the evacuated, perlite filled annular region of these tanks. Once inside, the extremely low temperatures will cause most of the air to freeze. If a significant mass of air is allowed to accumulate, severe damage can result from nominal draining operations. Collection of liquid air on the outer shell may chill it below its ductility range, resulting in fracture. Testing and analysis to quantify the thermal conductivity of perlite that has nitrogen frozen into its interstitial spaces and to determine the void fraction of frozen nitrogen within a perlite/frozen nitrogen mixture is presented. General equations to evaluate methods for removing frozen air, while avoiding fracture, are developed. A hypothetical leak is imposed on an existing tank geometry and a full analysis of that leak is detailed. This analysis includes a thermal model of the tank and a time-to-failure calculation. Approaches to safely remove the frozen air are analyzed, leading to the conclusion that the most feasible approach is to allow the frozen air to melt and to use a water stream to prevent the outer shell from chilling.

Rapid Surface Detection of CO2 Leaks from Geologic Sequestration Sites

NASA Astrophysics Data System (ADS)

Moriarty, D. M.; Krevor, S. C.; Benson, S. M.

2013-12-01

Carbon sequestration is becoming a viable option for global CO2 mitigation but effective monitoring methods are needed assure the carbon dioxide stays underground. Above surface monitoring using a mobile gas analyzer is one such method (e.g. Krevor et al., 2010). The Picarro gas analyzer uses wavelength-scanned cavity ring down spectroscopy to accurately identify concentrations of various atmospheric gases including their isotopic composition. These measurements can then be used for anomaly (leak) detection and source attribution. Leaks are detected by anomalous absolute concentration of CO2 and anomalous δ13C values. Source attribution is determined by the isotopic concentrations of the identified leaking gas. To distinguish between noise from ambient signals and leaks, a method based on mixing ratios has been developed. A newly acquired data set presented here has been collected from a 3.7km2 area with naturally occurring CO2 springs near Green River, Utah. All of the areas of known leakage were readily detected using this method along with several other areas that showed significant signs of leakage. In addition, testing on the Stanford campus has shown that this method is sensitive enough to distinguish between open fields and roadways. Another data set is being collected at Montana State University at the ZERT monitoring test site where an artificial leak has been created for the purpose of testing leak detection and quantification methods. Data collected from this site are being used for (1) assessing of detection levels and how they depend on environmental parameters such as wind speed, and acquisition variables such as sample rate and traverse speed, (2) optimizing acquisition parameters to increase detection levels and increase confidence in leak detection, (3) evaluating the potential for quantifying the magnitude of the leak and (4) spatial data analysis to identify the most probable leak locations.

Ultrasonic Detectors Safely Identify Dangerous, Costly Leaks

NASA Technical Reports Server (NTRS)

2013-01-01

In 1990, NASA grounded its space shuttle fleet. The reason: leaks detected in the hydrogen fuel systems of the Space Shuttles Atlantis and Columbia. Unless the sources of the leaks could be identified and fixed, the shuttles would not be safe to fly. To help locate the existing leaks and check for others, Kennedy Space Center engineers used portable ultrasonic detectors to scan the fuel systems. As a gas or liquid escapes from a leak, the resulting turbulence creates ultrasonic noise, explains Gary Mohr, president of Elmsford, New York-based UE Systems Inc., a long-time leader in ultrasonic detector technologies. "In lay terms, the leak is like a dog whistle, and the detector is like the dog ear." Because the ultrasound emissions from a leak are highly localized, they can be used not only to identify the presence of a leak but also to help pinpoint a leak s location. The NASA engineers employed UE s detectors to examine the shuttle fuel tanks and solid rocket boosters, but encountered difficulty with the devices limited range-certain areas of the shuttle proved difficult or unsafe to scan up close. To remedy the problem, the engineers created a long-range attachment for the detectors, similar to "a zoom lens on a camera," Mohr says. "If you are on the ground, and the leak is 50 feet away, the detector would now give you the same impression as if you were only 25 feet away." The enhancement also had the effect of reducing background noise, allowing for a clearer, more precise detection of a leak s location.

Leak Rate Quantification Method for Gas Pressure Seals with Controlled Pressure Differential

NASA Technical Reports Server (NTRS)

Daniels, Christopher C.; Braun, Minel J.; Oravec, Heather A.; Mather, Janice L.; Taylor, Shawn C.

2015-01-01

An enhancement to the pressure decay leak rate method with mass point analysis solved deficiencies in the standard method. By adding a control system, a constant gas pressure differential across the test article was maintained. As a result, the desired pressure condition was met at the onset of the test, and the mass leak rate and measurement uncertainty were computed in real-time. The data acquisition and control system were programmed to automatically stop when specified criteria were met. Typically, the test was stopped when a specified level of measurement uncertainty was attained. Using silicone O-ring test articles, the new method was compared with the standard method that permitted the downstream pressure to be non-constant atmospheric pressure. The two methods recorded comparable leak rates, but the new method recorded leak rates with significantly lower measurement uncertainty, statistical variance, and test duration. Utilizing this new method in leak rate quantification, projects will reduce cost and schedule, improve test results, and ease interpretation between data sets.

Quantitative computed tomography versus spirometry in predicting air leak duration after major lung resection for cancer.

PubMed

Ueda, Kazuhiro; Kaneda, Yoshikazu; Sudo, Manabu; Mitsutaka, Jinbo; Li, Tao-Sheng; Suga, Kazuyoshi; Tanaka, Nobuyuki; Hamano, Kimikazu

2005-11-01

Emphysema is a well-known risk factor for developing air leak or persistent air leak after pulmonary resection. Although quantitative computed tomography (CT) and spirometry are used to diagnose emphysema, it remains controversial whether these tests are predictive of the duration of postoperative air leak. Sixty-two consecutive patients who were scheduled to undergo major lung resection for cancer were enrolled in this prospective study to define the best predictor of postoperative air leak duration. Preoperative factors analyzed included spirometric variables and area of emphysema (proportion of the low-attenuation area) that was quantified in a three-dimensional CT lung model. Chest tubes were removed the day after disappearance of the air leak, regardless of pleural drainage. Univariate and multivariate proportional hazards analyses were used to determine the influence of preoperative factors on chest tube time (air leak duration). By univariate analysis, site of resection (upper, lower), forced expiratory volume in 1 second, predicted postoperative forced expiratory volume in 1 second, and area of emphysema (< 1%, 1% to 10%, > 10%) were significant predictors of air leak duration. By multivariate analysis, site of resection and area of emphysema were the best independent determinants of air leak duration. The results were similar for patients with a smoking history (n = 40), but neither forced expiratory volume in 1 second nor predicted postoperative forced expiratory volume in 1 second were predictive of air leak duration. Quantitative CT is superior to spirometry in predicting air leak duration after major lung resection for cancer. Quantitative CT may aid in the identification of patients, particularly among those with a smoking history, requiring additional preventive procedures against air leak.

Leak detection using structure-borne noise

NASA Technical Reports Server (NTRS)

Holland, Stephen D. (Inventor); Roberts, Ronald A. (Inventor); Chimenti, Dale E. (Inventor)

2010-01-01

A method for detection and location of air leaks in a pressure vessel, such as a spacecraft, includes sensing structure-borne ultrasound waveforms associated with turbulence caused by a leak from a plurality of sensors and cross correlating the waveforms to determine existence and location of the leak. Different configurations of sensors and corresponding methods can be used. An apparatus for performing the methods is also provided.

A multicenter study of routine versus selective intraoperative leak testing for sleeve gastrectomy.

PubMed

Bingham, Jason; Kaufman, Jedediah; Hata, Kai; Dickerson, James; Beekley, Alec; Wisbach, Gordon; Swann, Jacob; Ahnfeldt, Eric; Hawkins, Devon; Choi, Yong; Lim, Robert; Martin, Matthew

2017-09-01

Staple line leaks after sleeve gastrectomy are dreaded complications. Many surgeons routinely perform an intraoperative leak test (IOLT) despite little evidence to validate the reliability, clinical benefit, and safety of this procedure. To determine the efficacy of IOLT and if routine use has any benefit over selective use. Eight teaching hospitals, including private, university, and military facilities. A multicenter, retrospective analysis over a 5-year period. The efficacy of the IOLT for identifying unsuspected staple line defects and for predicting postoperative leaks was evaluated. An anonymous survey was also collected reflecting surgeons' practices and beliefs regarding IOLT. From January 2010 through December 2014, 4284 patients underwent sleeve gastrectomy. Of these, 37 patients (.9%) developed a postoperative leak, and 2376 patients (55%) received an IOLT. Only 2 patients (0.08%) had a positive finding. Subsequently, 21 patients with a negative IOLT developed a leak. IOLT demonstrated a sensitivity of only 8.7%. There was a nonsignificant trend toward increased leak rates when an IOLT was performed versus when IOLT was not performed. Leak rates were not statistically different between centers that routinely perform IOLT versus those that selectively perform IOLT. Routine IOLT had very poor sensitivity and was negative in 91% of patients who later developed postoperative leaks. The use of IOLT was not associated with a decrease in the incidence of postoperative leaks, and routine IOLT had no benefit over selective leak testing. IOLT should not be used as a quality indicator or "best practice" for bariatric surgery. Published by Elsevier Inc.

Impact of the Surgical Experience on Leak Rate After Laparoscopic Sleeve Gastrectomy.

PubMed

Noel, Patrick; Nedelcu, Marius; Gagner, Michel

2016-08-01

Laparoscopic sleeve gastrectomy (LSG) has become one of the most commonly performed bariatric procedures, largely due to several advantages it carries over more complex bariatric procedures. LSG is generally considered a straightforward procedure, but one of the major concerns is a staple line leak. The objectives of this study are to evaluate the correlation between surgeon's experience and leak rate and to assess the different risk factors for developing a gastric leak after LSG. Private hospital, France. The analysis of a single surgeon's yearly leak rate since the introduction of LSG for possible risk factors was done. A total of 2012 LSGs were performed in between September, 2005 and December, 2014. Twenty cases (1 %) of gastric leak were recorded. Of these, 17 patients were women (94.4 %) with a mean age of 39.4 years (range 22-61) and mean body mass index (BMI) 41.2 kg/m(2) (range 34.8-57.1). On a yearly basis, the leak rate was 4.8 % (2006), 5.7 % (2007), 0 (2008), 2.6 % (2009), 2 % (2010), 0.8 % (2011), 0.6 % (2012), 0.2 % (2013), and 0 (2014). In the first 1000 cases (group A), there were 18 cases of gastric leak and in the last 1000 cases, there were 800 with GORE® SEAMGUARD® Bioabsorbable Staple Line Reinforcement (group B) 2 cases of gastric leak (p = 0.009). A revisional LSG, 395 patients after gastric banding and 61 patients re-sleeve gastrectomy, was performed in 456 cases (22.7 %). There were 3 cases of leak (0.65 %). There were two deaths. LSG can be performed with a low complication rate. This large series of a single surgeon's experience demonstrated that the leak rate after LSG could be significantly decreased over time with changes in techniques.

Can the intraoperative leak test prevent postoperative leakage of esophagojejunal anastomosis after total gastrectomy?

PubMed

Kanaji, Shingo; Ohyama, Masato; Yasuda, Takashi; Sendo, Hiroyoshi; Suzuki, Satoshi; Kawasaki, Kentaro; Tanaka, Kenichi; Fujino, Yasuhiro; Tominaga, Masahiro; Kakeji, Yoshihiro

2016-07-01

Anastomotic failures that cannot be detected during surgery often lead to postoperative leakage. There have been no detailed reports on the intraoperative leak test for esophagojejunal anastomosis. Our purpose was to investigate the utility of routine intraoperative leak testing to prevent postoperative anastomotic leakage after performing esophagojejunostomy. We prospectively performed routine air leak tests and reviewed the records of 185 consecutive patients with gastric cancer who underwent open total gastrectomy followed by esophagojejunostomy. A positive leak test was found for six patients (3.2 %). These patients with positive leak tests were subsequently treated with additional suturing, and they developed no postoperative anastomotic leakage. However, anastomotic leakage occurred in nine patients (4.9 %) with negative leak tests. A multivariate analysis demonstrated that a patient age >75 years and the surgeon's experience <30 cases were risk factors for anastomotic leakage. Intraoperative leak testing can detect some physical dehiscence, and additional suturing may prevent anastomotic leakage. However, it cannot prevent all anastomotic leakage caused by other factors, such as the surgeons' experience and patients' age.

High sensitivity leak detection method and apparatus

DOEpatents

Myneni, Ganapatic R.

1994-01-01

An improved leak detection method is provided that utilizes the cyclic adsorption and desorption of accumulated helium on a non-porous metallic surface. The method provides reliable leak detection at superfluid helium temperatures. The zero drift that is associated with residual gas analyzers in common leak detectors is virtually eliminated by utilizing a time integration technique. The sensitivity of the apparatus of this disclosure is capable of detecting leaks as small as 1.times.10.sup.-18 atm cc sec.sup.-1.

Microseismic response characteristics modeling and locating of underground water supply pipe leak

NASA Astrophysics Data System (ADS)

Wang, J.; Liu, J.

2015-12-01

In traditional methods of pipeline leak location, geophones must be located on the pipe wall. If the exact location of the pipeline is unknown, the leaks cannot be identified accurately. To solve this problem, taking into account the characteristics of the pipeline leak, we propose a continuous random seismic source model and construct geological models to investigate the proposed method for locating underground pipeline leaks. Based on two dimensional (2D) viscoacoustic equations and the staggered grid finite-difference (FD) algorithm, the microseismic wave field generated by a leaking pipe is modeled. Cross-correlation analysis and the simulated annealing (SA) algorithm were utilized to obtain the time difference and the leak location. We also analyze and discuss the effect of the number of recorded traces, the survey layout, and the offset and interval of the traces on the accuracy of the estimated location. The preliminary results of the simulation and data field experiment indicate that (1) a continuous random source can realistically represent the leak microseismic wave field in a simulation using 2D visco-acoustic equations and a staggered grid FD algorithm. (2) The cross-correlation method is effective for calculating the time difference of the direct wave relative to the reference trace. However, outside the refraction blind zone, the accuracy of the time difference is reduced by the effects of the refracted wave. (3) The acquisition method of time difference based on the microseismic theory and SA algorithm has a great potential for locating leaks from underground pipelines from an array located on the ground surface. Keywords: Viscoacoustic finite-difference simulation; continuous random source; simulated annealing algorithm; pipeline leak location

Analysis of lactate concentrations in canine synovial fluid.

PubMed

Proot, J L J; de Vicente, F; Sheahan, D E

2015-01-01

To report synovial fluid lactate concentrations in normal and pathological canine joints. Controlled, prospective study. Lactate was measured in synovial fluid using a hand-held meter and the rest of the fluid was sent to a commercial laboratory for analysis. Samples were divided into four groups; group 1: control, group 2: osteoarthritis, group 3: immune-mediated inflammatory arthritis, and group 4: septic arthritis. Statistical analysis was performed to compare lactate concentrations between the four groups and to examine the predictive value of lactate in the diagnosis of septic arthritis. A correlation was sought between synovial fluid lactate and synovial fluid total nucleated cell count and total protein. Seventy-four samples were investigated from 55 dogs. Statistical analysis found that lactate concentrations were significantly higher in the septic arthritis group than in each of the other three groups. No significant correlation could be found between synovial fluid lactate concentrations and synovial fluid total nucleated cell count or synovial fluid total protein. Lactate concentration was found to be a useful predictor of septic arthritis, with a low concentration pointing towards exclusion rather than a high concentration to the diagnosis of septic arthritis. Synovial fluid lactate concentration is not a good marker for osteoarthritis or immune-mediated inflammatory arthritis, but it is significantly increased in septic arthritis and could help the clinician in ruling out this condition in a quick and cost-effective way.

Distribution System Audits, Leak Detection, and Repair: Kirtland Air Force Base Leak Detection and Repair Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Water Best Management Practice #3 Fact Seet: Outlines how a leak detection and repair program helped Kirtland Air Force Base perform distribution system audits, leak detection, and repair to conserve water site-wide.

49 CFR 195.444 - CPM leak detection.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false CPM leak detection. 195.444 Section 195.444... PIPELINE Operation and Maintenance § 195.444 CPM leak detection. Each computational pipeline monitoring (CPM) leak detection system installed on a hazardous liquid pipeline transporting liquid in single...

The Fourth Annual Thermal and Fluids Analysis Workshop

NASA Technical Reports Server (NTRS)

1992-01-01

The Fourth Annual Thermal and Fluids Analysis Workshop was held from August 17-21, 1992, at NASA Lewis Research Center. The workshop consisted of classes, vendor demonstrations, and paper sessions. The classes and vendor demonstrations provided participants with the information on widely used tools for thermal and fluids analysis. The paper sessions provided a forum for the exchange of information and ideas among thermal and fluids analysts. Paper topics included advances and uses of established thermal and fluids computer codes (such as SINDA and TRASYS) as well as unique modeling techniques and applications.

Automated Hydrogen Gas Leak Detection System

NASA Technical Reports Server (NTRS)

1995-01-01

The Gencorp Aerojet Automated Hydrogen Gas Leak Detection System was developed through the cooperation of industry, academia, and the Government. Although the original purpose of the system was to detect leaks in the main engine of the space shuttle while on the launch pad, it also has significant commercial potential in applications for which there are no existing commercial systems. With high sensitivity, the system can detect hydrogen leaks at low concentrations in inert environments. The sensors are integrated with hardware and software to form a complete system. Several of these systems have already been purchased for use on the Ford Motor Company assembly line for natural gas vehicles. This system to detect trace hydrogen gas leaks from pressurized systems consists of a microprocessor-based control unit that operates a network of sensors. The sensors can be deployed around pipes, connectors, flanges, and tanks of pressurized systems where leaks may occur. The control unit monitors the sensors and provides the operator with a visual representation of the magnitude and locations of the leak as a function of time. The system can be customized to fit the user's needs; for example, it can monitor and display the condition of the flanges and fittings associated with the tank of a natural gas vehicle.

CT-Guided Percutaneous Drainage of Infected Collections Due to Gastric Leak After Sleeve Gastrectomy for Morbid Obesity: Initial Experience

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kelogrigoris, M., E-mail: kelogre.mic@hotmail.com; Sotiropoulou, E.; Stathopoulos, K.

This study was designed to evaluate the efficacy and safety of computed tomography (CT)-guided drainage in treating infected collections due to gastric leak after laparoscopic sleeve gastrectomy for morbid obesity. From January 2007 to June 2009, 21 patients (9 men and 12 women; mean age, 39.2 (range, 26-52) years) with infected collections due to gastric leak after laparoscopic sleeve gastrectomy for morbid obesity underwent image-guided percutaneous drainage. All procedures were performed using CT guidance and 8- to 12-Fr pigtail drainage catheters. Immediate technical success was achieved in all 21 infected collections. In 18 of 21 collections, we obtained progressive shrinkagemore » of the collection with consequent clinical success (success rate 86%). In three cases, the abdominal fluid collection was not resolved, and the patients were reoperated. Among the 18 patients who avoided surgery, 2 needed replacement of the catheter due to obstruction. No major complications occurred during the procedure. The results of our study support that CT-guided percutaneous drainage is an effective and safe method to treat infected abdominal fluid collections due to gastric leak in patients who had previously underwent laparoscopic sleeve gastrectomy for morbid obesity. It may be considered both as a preparatory step for surgery and a valuable alternative to open surgery. Failure of the procedure does not, however, preclude a subsequent surgical operation.« less

Group invariant solution for a pre-existing fracture driven by a power-law fluid in permeable rock

NASA Astrophysics Data System (ADS)

Fareo, A. G.; Mason, D. P.

2016-06-01

Group invariant analytical and numerical solutions for the evolution of a two-dimensional fracture with nonzero initial length in permeable rock and driven by an incompressible non-Newtonian fluid of power-law rheology are obtained. The effect of fluid leak-off on the evolution of the power-law fluid fracture is investigated.

Preoperative Detection of Sarcopenic Obesity Helps to Predict the Occurrence of Gastric Leak After Sleeve Gastrectomy.

PubMed

Gaillard, Martin; Tranchart, Hadrien; Maitre, Sophie; Perlemuter, Gabriel; Lainas, Panagiotis; Dagher, Ibrahim

2018-03-02

Sleeve gastrectomy (SG) has become the primary procedure for many bariatric teams and staple-line leak represents its most feared complication. Sarcopenic obesity combines the risks of obesity and depleted lean mass leading possibly to an inferior surgical outcome after abdominal surgery. The aim of this study was to evaluate the existence of a potential link between radiologically determined sarcopenic obesity and staple-line leak risk after SG. A retrospective analysis of a prospective database was performed in consecutive patients undergoing SG as primary procedure. Total psoas muscles (TPA) and total visible muscles (TMA) areas were measured on a preoperative computed tomography (CT). Sarcopenia was defined as lowest tertile of skeletal muscular mass indexes (muscular areas over square of height) in each gender (using TPA or TMA). Multivariate analysis was performed to determine preoperative risk factors for staple-line leak. During the study period, 205 patients were included in the analysis. Median BMI was 40.8 kg/m 2 (34.2-49.6), and 9 patients (4.4%) presented a gastric leak. The sex-specific cut-offs for skeletal muscular mass index according to TPA were 8.2 cm 2 /m 2 for men and 6.08 cm 2 /m 2 for women. After multivariate analysis, preoperative weight (OR = 1043) and sarcopenia (TPA) (OR = 5204) were independent predictive factors for gastric leak. The present series suggests that CT scan-determined sarcopenic obesity is associated with increased risk of gastric leak after SG. This preoperatively radiological examination would be a useful clinical tool to tailor patient management according to gastric leak risk.

Sensitivities of Soap Solutions in Leak Detection

NASA Technical Reports Server (NTRS)

Stuck, D.; Lam, D. Q.; Daniels, C.

1985-01-01

Document describes method for determining minimum leak rate to which soap-solution leak detectors sensitive. Bubbles formed at smaller leak rates than previously assumed. In addition to presenting test results, document discusses effects of joint-flange configurations, properties of soap solutions, and correlation of test results with earlier data.

High sensitivity leak detection method and apparatus

DOEpatents

Myneni, G.R.

1994-09-06

An improved leak detection method is provided that utilizes the cyclic adsorption and desorption of accumulated helium on a non-porous metallic surface. The method provides reliable leak detection at superfluid helium temperatures. The zero drift that is associated with residual gas analyzers in common leak detectors is virtually eliminated by utilizing a time integration technique. The sensitivity of the apparatus of this disclosure is capable of detecting leaks as small as 1 [times] 10[sup [minus]18] atm cc sec[sup [minus]1]. 2 figs.

An Integrated Solution for Performing Thermo-fluid Conjugate Analysis

NASA Technical Reports Server (NTRS)

Kornberg, Oren

2009-01-01

A method has been developed which integrates a fluid flow analyzer and a thermal analyzer to produce both steady state and transient results of 1-D, 2-D, and 3-D analysis models. The Generalized Fluid System Simulation Program (GFSSP) is a one dimensional, general purpose fluid analysis code which computes pressures and flow distributions in complex fluid networks. The MSC Systems Improved Numerical Differencing Analyzer (MSC.SINDA) is a one dimensional general purpose thermal analyzer that solves network representations of thermal systems. Both GFSSP and MSC.SINDA have graphical user interfaces which are used to build the respective model and prepare it for analysis. The SINDA/GFSSP Conjugate Integrator (SGCI) is a formbase graphical integration program used to set input parameters for the conjugate analyses and run the models. The contents of this paper describes SGCI and its thermo-fluids conjugate analysis techniques and capabilities by presenting results from some example models including the cryogenic chill down of a copper pipe, a bar between two walls in a fluid stream, and a solid plate creating a phase change in a flowing fluid.

Noble Gas Leak Detector for Use in the SNS Neutron Electric Dipole Moment Experiment

NASA Astrophysics Data System (ADS)

Barrow, Chad; Huffman, Paul; Leung, Kent; Korobkina, Ekaterina; White, Christian; nEDM Collaboration Collaboration

2017-09-01

Common practice for leak-checking high vacuum systems uses helium as the probing gas. However, helium may permeate some materials at room temperature, making leak characterization difficult. The experiment to find a permanent electric dipole moment of the neutron (nEDM), to be conducted at Oak Ridge National Laboratories, will employ a large volume of liquid helium housed by such a helium-permeable composite material. It is desirable to construct a leak detector that can employ alternative test gases. The purpose of this experiment is to create a leak detector that can quantify the argon gas flux in a high vacuum environment and interpret this flux as a leak-rate. This apparatus will be used to check the nEDM volumes for leaks at room temperature before cooling down to cryogenic temperatures. Our leak detector uses a residual gas analyzer and a vacuum pumping station to characterize the gas present in an evacuated volume. The introduction of argon gas into the system is interpreted as a leak-rate into the volume. The device has been calibrated with NIST certified calibrated leaks and the machine's sensitivity has been calculated using background gas analysis. As a result of the device construction and software programming, we are able to leak-check composite and polyamide volumes This work was supported in part by the US Department of Energy under Grant No. DE-FG02-97ER41042.

Theoretical and experimental investigation into structural and fluid motions at low frequencies in water distribution pipes

NASA Astrophysics Data System (ADS)

Gao, Yan; Liu, Yuyou

2017-06-01

Vibrational energy is transmitted in buried fluid-filled pipes in a variety of wave types. Axisymmetric (n = 0) waves are of practical interest in the application of acoustic techniques for the detection of leaks in underground pipelines. At low frequencies n = 0 waves propagate longitudinally as fluid-dominated (s = 1) and shell-dominated (s = 2) waves. Whilst sensors such as hydrophones and accelerometers are commonly used to detect leaks in water distribution pipes, the mechanism governing the structural and fluid motions is not well documented. In this paper, the low-frequency behaviour of the pipe wall and the contained fluid is investigated. For most practical pipework systems, these two waves are strongly coupled; in this circumstance the ratios of the radial pipe wall displacements along with the internal pressures associated with these two wave types are obtained. Numerical examples show the relative insensitivity of the structural and fluid motions to the s = 2 wave for both metallic and plastic pipes buried in two typical soils. It is also demonstrated that although both acoustic and vibration sensors at the same location provide the identical phase information of the transmitted signals, pressure responses have significantly higher levels than acceleration responses, and thus hydrophones are better suited in a low signal-to-noise ratio (SNR) environment. This is supported by experimental work carried out at a leak detection facility. Additional pressure measurements involved excitation of the fluid and the pipe fitting (hydrant) on a dedicated water pipe. This work demonstrates that the s = 1 wave is mainly responsible for the structural and fluid motions at low frequencies in water distribution pipes as a result of water leakage and direct pipe excitation.

40 CFR 63.424 - Standards: Equipment leaks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Standards: Equipment leaks. 63.424....424 Standards: Equipment leaks. (a) Each owner or operator of a bulk gasoline terminal or pipeline breakout station subject to the provisions of this subpart shall perform a monthly leak inspection of all...

The Predictive Value of Coefficient of PCT × BG for Anastomotic Leak in Esophageal Carcinoma Patients With ARDS After Esophagectomy.

PubMed

Li, Huan; Wang, Daofeng; Wei, Wenxiao; Ouyang, Lamei; Lou, Ning

2017-01-01

Anastomotic leak was a potentially severe life-threatening complication of esophagectomy, which drew attention in consequence of progressive dyspnea until acute respiratory distress syndrome (ARDS) due to the early asymptomatic presentation. Respiratory failure, caused by ARDS as the severe presentation of anastomotic leak, is the most common organ failure. CRP (C-reactive protein), procalcitonin (PCT), and Blood G (BG) test are the sensitivity markers for inflammatory, sepsis, and fungemia, respectively. Early recognition and intervention treatment of anastomotic leak may alleviate complication and improve outcome. We retrospectively analyzed 71 patients, accepting mechanical ventilation support because of ARDS as the complication after radical resection of esophagus cancer. Clinical data were collected from the patients' electronic medical records, including their clinically hematological examination, drainage fluid cultures, and sputum culture. Accord to appearance of anastomotic leak or not, all patients were divided into 2 groups, leak group and no-leak group. Inflammatory markers, such as CRP, PCT, and the coefficient of BG and PCT, were significantly different between the 2 groups. Respiratory index, white blood cell, hemoglobin (HBG), platelet (PLT), and other clinical factors were not significantly different between the 2 groups. Receiver operating characteristic curves were constructed to calculate the sensitivity, specificity, positive predictive value, negative predictive value, and area under the curve for various cutoff levels of several factors. Blood G tests presented the better predicting value for anastomotic leak. Blood G tests and PCT should be tested after esophagectomy. The coefficient of PCT and BG (>260) is of great significance, and clinical value to predict anastomotic leak for patients with postesophagectomy ARDS, early PCT and BG test, and especially, dynamic variation may alleviate complication and improve outcome.

The minimal leak test technique for endotracheal cuff maintenance.

PubMed

Harvie, D A; Darvall, J N; Dodd, M; De La Cruz, A; Tacey, M; D'Costa, R L; Ward, D

2016-09-01

Endotracheal tube (ETT) cuff pressure management is an essential part of airway management in intubated and mechanically ventilated patients. Both under- and over-inflation of the ETT cuff can lead to patient complications, with an ideal pressure range of 20-30 cmH 2 O defined. A range of techniques are employed to ensure adequate ETT cuff inflation, with little comparative data. We performed an observational cross-sectional study in a tertiary metropolitan ICU, assessing the relationship between the minimal leak test and cuff manometry. Forty-five mechanically ventilated patients, over a three-month period, had ETT cuff manometry performed at the same time as their routine cuff maintenance (minimal leak test). Bedside nurse measurements were compared with investigator measurements. At the endpoint of cuff inflation, 20 of 45 patients (44%) had cuff pressures between 20 and 30 cmH 2 O; 11 of 45 patients (24%) had cuff pressures <20 cmH 2 O; 14 of 45 patients (31%) had cuff pressures ≥30 cmH 2 O. Univariate analysis demonstrated an association between both patient obesity and female gender requiring less ETT cuff volume ( P =0.008 and P <0.001 respectively), though this association was lost on multivariate analysis. No association was demonstrated between any measured variables and cuff pressures. Inter-operator reliability in performing the minimal leak test showed no evidence of bias between nurse and investigators (Pearson coefficient = 0.897). We conclude the minimal leak test for maintenance of ETT cuffs leads to both over- and under-inflation, and alternative techniques, such as cuff manometry, should be employed.

40 CFR 63.691 - Standards: Equipment leaks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Standards: Equipment leaks. 63.691....691 Standards: Equipment leaks. (a) The provisions of this section apply to the control of air emissions from equipment leaks for which § 63.683(d) references the use of this section for such air...

Leak Detection in Spacecraft Using a 64-Element Multiplexed Passive Array to Monitor Structure-Borne Noise

NASA Astrophysics Data System (ADS)

Holland, Stephen D.; Song, Jun-Ho; Chimenti, D. E.; Roberts, Ron

2006-03-01

We demonstrate an array sensor method intended to locate leaks in manned spacecraft using leak-generated, structure-borne ultrasonic noise. We have developed and tested a method for sensing and processing leak noise to reveal the leak location involving the use of a 64-element phased-array. Cross-correlations of ultrasonic noise waveforms from a leak into vacuum have been used with a phased-array analysis to find the direction from the sensor to the leak. This method measures the propagation of guided ultrasonic Lamb waves passing under the PZT array sensor in the spacecraft skin structure. This paper will describe the custom-designed array with integrated electronics, as well as the performance of the array in prototype applications. We show that this method can be used to successfully locate leaks to within a few millimeters on a 0.6-m square aluminum plate.

A Leak Monitor for Industry

NASA Technical Reports Server (NTRS)

1996-01-01

GenCorp Aerojet Industrial Products, Lewis Research Center, Marshall Space Flight Center, and Case Western Reserve University developed a gas leak detection system, originally for use with the Space Shuttle propulsion system and reusable launch vehicles. The Model HG200 Automated Gas Leak Detection System has miniaturized sensors that can identify extremely low concentrations of hydrogen without requiring oxygen. A microprocessor-based hardware/software system monitors the sensors and displays the source and magnitude of hydrogen leaks in real time. The system detects trace hydrogen around pipes, connectors, flanges and pressure tanks, and has been used by Ford Motor Company in the production of a natural gas-powered car.

Improved gaseous leak detector

DOEpatents

Juravic, F.E. Jr.

1983-10-06

In a short path length mass-spectrometer type of helium leak detector wherein the helium trace gas is ionized, accelerated and deflected onto a particle counter, an arrangement is provided for converting the detector to neon leak detection. The magnetic field of the deflection system is lowered so as to bring the nonlinear fringe area of the magnetic field across the ion path, thereby increasing the amount of deflection of the heavier neon ions.

Optimal sensor placement for leak location in water distribution networks using genetic algorithms.

PubMed

Casillas, Myrna V; Puig, Vicenç; Garza-Castañón, Luis E; Rosich, Albert

2013-11-04

This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs). The sensor placement problem is formulated as an integer optimization problem. The optimization criterion consists in minimizing the number of non-isolable leaks according to the isolability criteria introduced. Because of the large size and non-linear integer nature of the resulting optimization problem, genetic algorithms (GAs) are used as the solution approach. The obtained results are compared with a semi-exhaustive search method with higher computational effort, proving that GA allows one to find near-optimal solutions with less computational load. Moreover, three ways of increasing the robustness of the GA-based sensor placement method have been proposed using a time horizon analysis, a distance-based scoring and considering different leaks sizes. A great advantage of the proposed methodology is that it does not depend on the isolation method chosen by the user, as long as it is based on leak sensitivity analysis. Experiments in two networks allow us to evaluate the performance of the proposed approach.

Optimal Sensor Placement for Leak Location in Water Distribution Networks Using Genetic Algorithms

PubMed Central

Casillas, Myrna V.; Puig, Vicenç; Garza-Castañón, Luis E.; Rosich, Albert

2013-01-01

This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs). The sensor placement problem is formulated as an integer optimization problem. The optimization criterion consists in minimizing the number of non-isolable leaks according to the isolability criteria introduced. Because of the large size and non-linear integer nature of the resulting optimization problem, genetic algorithms (GAs) are used as the solution approach. The obtained results are compared with a semi-exhaustive search method with higher computational effort, proving that GA allows one to find near-optimal solutions with less computational load. Moreover, three ways of increasing the robustness of the GA-based sensor placement method have been proposed using a time horizon analysis, a distance-based scoring and considering different leaks sizes. A great advantage of the proposed methodology is that it does not depend on the isolation method chosen by the user, as long as it is based on leak sensitivity analysis. Experiments in two networks allow us to evaluate the performance of the proposed approach. PMID:24193099

Apparatus and method for fluid analysis

DOEpatents

Wilson, Bary W.; Peters, Timothy J.; Shepard, Chester L.; Reeves, James H.

2004-11-02

The present invention is an apparatus and method for analyzing a fluid used in a machine or in an industrial process line. The apparatus has at least one meter placed proximate the machine or process line and in contact with the machine or process fluid for measuring at least one parameter related to the fluid. The at least one parameter is a standard laboratory analysis parameter. The at least one meter includes but is not limited to viscometer, element meter, optical meter, particulate meter, and combinations thereof.

Probabilistic pipe fracture evaluations for leak-rate-detection applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahman, S.; Ghadiali, N.; Paul, D.

1995-04-01

Regulatory Guide 1.45, {open_quotes}Reactor Coolant Pressure Boundary Leakage Detection Systems,{close_quotes} was published by the U.S. Nuclear Regulatory Commission (NRC) in May 1973, and provides guidance on leak detection methods and system requirements for Light Water Reactors. Additionally, leak detection limits are specified in plant Technical Specifications and are different for Boiling Water Reactors (BWRs) and Pressurized Water Reactors (PWRs). These leak detection limits are also used in leak-before-break evaluations performed in accordance with Draft Standard Review Plan, Section 3.6.3, {open_quotes}Leak Before Break Evaluation Procedures{close_quotes} where a margin of 10 on the leak detection limit is used in determining the crackmore » size considered in subsequent fracture analyses. This study was requested by the NRC to: (1) evaluate the conditional failure probability for BWR and PWR piping for pipes that were leaking at the allowable leak detection limit, and (2) evaluate the margin of 10 to determine if it was unnecessarily large. A probabilistic approach was undertaken to conduct fracture evaluations of circumferentially cracked pipes for leak-rate-detection applications. Sixteen nuclear piping systems in BWR and PWR plants were analyzed to evaluate conditional failure probability and effects of crack-morphology variability on the current margins used in leak rate detection for leak-before-break.« less

Cryogenic fluid management experiment

NASA Technical Reports Server (NTRS)

Eberhardt, R. N.; Bailey, W. J.; Fester, D. A.

1981-01-01

The cryogenic fluid management experiment (CFME), designed to characterize subcritical liquid hydrogen storage and expulsion in the low-q space environment, is discussed. The experiment utilizes a fine mesh screen fluid management device to accomplish gas-free liquid expulsion and a thermodynamic vent system to intercept heat leak and control tank pressure. The experiment design evolved from a single flight prototype to provision for a multimission (up to 7) capability. A detailed design of the CFME, a dynamic test article, and dedicated ground support equipment were generated. All materials and parts were identified, and components were selected and specifications prepared. Long lead titanium pressurant spheres and the flight tape recorder and ground reproduce unit were procured. Experiment integration with the shuttle orbiter, Spacelab, and KSC ground operations was coordinated with the appropriate NASA centers, and experiment interfaces were defined. Phase 1 ground and flight safety reviews were conducted. Costs were estimated for fabrication and assembly of the CFME, which will become the storage and supply tank for a cryogenic fluid management facility to investigate fluid management in space.

40 CFR 264.196 - Response to leaks or spills and disposition of leaking or unfit-for-use tank systems.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Response to leaks or spills and... HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Tank Systems § 264.196 Response to leaks or... system from which there has been a leak or spill, or which is unfit for use, must be removed from service...

Technical basis for inner container leak detection sensitivity goals in 3013 DE surveillance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berg, John M.

Helium leak checking of 3013 inner container lids is under consideration for addition to DE Surveillance tasks as an improved means to detect any through-wall flaws that may have formed during storage. This white paper evaluates whether leak checking at DE could replace and improve upon the current method of comparing gas compositions and pressures within the inner and outer containers. We have used viscous and molecular flow equations in ANSI N14.5 to calculate what the measured standard helium leak rate would be for hypothetical leaks of three different sizes. For comparison, we have also calculated the effects on gasmore » composition and pressure differences as a function of pre-DE storage time for the same three leak sizes, using molecular and viscous flow equations as well as diffusion equations to predict the relevant gas transport. For a hypothetical leak that would be measured at 1x10 -7 std cc/sec, likely an achievable sensitivity using helium leak checking at DE, the calculations predict no measurable effect on pressure difference or gas composition as measured by DE gas analysis. We also calculate that it would take over 200 years for water vapor to diffuse through a 10 -7 std cc/sec leak enough to raise the RH outer container to half the RH value in the inner container. A leak 100 times larger, which would be measured at 1x10 -5 std cc/sec, the same water vapor diffusion would take at least 14 years. Our conclusion is that helium leak checking will be useful even at a sensitivity of 1x10 -5 std cc/sec, and a significant improvement over current DE methods at a sensitivity of 1x10 -7 std cc/sec.« less

Recent advances in the treatment of air leaks.

PubMed

Cerfolio, Robert James

2005-07-01

Alveolar-pleural fistulas (air leaks) are an extremely common clinical problem and remain the most common complication after elective pulmonary resection and video-assisted procedures. The decision making process used to manage air leaks and chest tubes that control them has been, until very recently, based on opinions and training preferences as opposed to facts derived from randomized clinical trials. Recently, several prospective randomized trials have studied air leaks. An objective, reproducible classification system has also been designed and clinically validated to help study air leaks. This system and these studies have shown that water seal is superior to wall suction to help stop most leaks. Even in patients with a pneumothorax and an air leak, water seal is safe and best; however, if a patient has a large leak (greater than an expiratory 3 on the classification system) or experiences subcutaneous emphysema or an expanding pneumothorax that causes hypoxia, then some suction (-10 cm of water) should be applied to the chest tubes. Air leaks were a poorly understood yet extremely common clinical problem that had never been scientifically studied. Over the past 5 years, prospective randomized studies have shown that water seal is the best setting for chest tubes and that a pneumothorax is not a contraindication to leaving tubes on seal. Further studies are needed to investigate the ideal management of alveolar-pleural fistulas (air leaks) in different clinical scenarios besides those that occur postoperatively.

The Fifth Annual Thermal and Fluids Analysis Workshop

NASA Technical Reports Server (NTRS)

1993-01-01

The Fifth Annual Thermal and Fluids Analysis Workshop was held at the Ohio Aerospace Institute, Brook Park, Ohio, cosponsored by NASA Lewis Research Center and the Ohio Aerospace Institute, 16-20 Aug. 1993. The workshop consisted of classes, vendor demonstrations, and paper sessions. The classes and vendor demonstrations provided participants with the information on widely used tools for thermal and fluid analysis. The paper sessions provided a forum for the exchange of information and ideas among thermal and fluids analysts. Paper topics included advances and uses of established thermal and fluids computer codes (such as SINDA and TRASYS) as well as unique modeling techniques and applications.

Space Station Freedom seal leakage rate analysis and testing summary: Air leaks in ambient versus vacuum exit conditions

NASA Technical Reports Server (NTRS)

Rodriguez, P. I.; Markovitch, R.

1992-01-01

This report is intended to reveal the apparent relationship of air seal leakage rates between 2 atmospheres (atm) to 1 atm and 1 atm to vacuum conditions. Gas dynamics analysis is provided as well as data summarizing the MSFC test report, 'Space Station Freedom (S.S. Freedom) Seal Flaw Study With Delta Pressure Leak Rate Comparison Test Report'.

Hydrogen leak detection in the Space Shuttle

NASA Technical Reports Server (NTRS)

Barile, Ronald G

1992-01-01

This study focuses on a helium gas jet flowing into room air. Measurements of helium concentration and velocity in the jet-air mixture are reported. The objective is to learn about jet characteristics so that dynamically similar hydrogen leaks may be located in the Space Shuttle. The hazardous gas detection system (HGDS) in the mobile launch pad uses mass spectrometers to monitor the shuttle environment for leaks. The mass spectrometers are fed by long sample tubes which draw gas from the payload bay, mid body, aft engine compartment and external tank. The overall purpose of this study is to improve the HGDS especially in its potential for locating hydrogen leaks. A rapid-response leak detection experiment was designed, built, and tested, following on the work done in this program last summer. The apparatus included a Perkin Elmer MGA-1200 mass spectrometer and air velocity transducer, both monitored by a Macintosh IIFX computer using LabVIEW software. A jet of helium flowing into the lab air simulated a gas leak. Steady helium or hydrogen-nitrogen jets were logged for concentration and velocity, and the power spectral density of each was computed. Last year, large eddies and vortices were visually seen with Schlieren imaging, and they were detected in the time plots of the various instruments. The response time of the MGA-1200 was found in the range of 0.05 to 0.1 sec. Pulsed concentration waves were clearly detected at 25 cycles per sec by spectral analysis of MGA data. No peaks were detected in the power spectrum, so in the present study, 10 Hz bandwidth-averaged power levels were examined at regular frequency intervals. The practical consequences of last year's study are as follows: sampling frequency should be increased above the present rate of 1 sample per second so that transients could be observed and analyzed with frequency response methods. Many more experiments and conditions were observed in this second summer, including the effects of orifice diameter

Anastomotic Leaks After Restorative Resections for Rectal Cancer Compromise Cancer Outcomes and Survival.

PubMed

Lu, Zheqin R; Rajendran, Nirooshun; Lynch, A Craig; Heriot, Alexander G; Warrier, Satish K

2016-03-01

Anastomotic leaks after restorative resections for rectal cancer may lead to worse long-term outcomes. The purpose of this study was to evaluate the best current evidence assessing anastomotic leaks in rectal cancer resections with curative intent and their impact on survival and cancer recurrence. A meta-analysis was performed using MEDLINE, EMBASE, and Cochrane search engines for relevant studies published between January 1982 and January 2015. Preferred Reporting Items for Systematic Reviews and Meta-Analyses methodology was used to screen and select relevant studies for the review using key words "colorectal surgery; colorectal neoplasm; rectal neoplasm" and "anastomotic leak." Anastomotic leak groups were compared with nonanastomotic leak groups. ORs were calculated from binary data for local recurrence, distant recurrence, and cancer-specific mortality. A random-effects model was then used to calculate pooled ORs with 95% CIs. Eleven studies with 13,655 patients met the inclusion criteria. This included 5 prospective cohort and 6 retrospective cohort studies. Median follow-up was 60 months. Higher cancer-specific mortality was noted in the leak group with an OR of 1.30 (95% CI, 1.04-1.62; p < 0.05). Local recurrences were more likely in rectal cancer resections complicated by anastomotic leaks (OR = 1.61 (95% CI, 1.25-2.09); p < 0.001). Distant recurrence was not more likely in the anastomotic leak group (OR = 1.07 (95% CI, 0.87-1.33); p = 0.52). All 11 studies are level 3 evidence cohort studies. Additional sensitivity analyses were performed to minimize cross-study heterogeneity. Anastomotic leaks after restorative resections for rectal cancer adversely impact cancer-specific mortality and local recurrence.

What is the optimal management of an intra-operative air leak in a colorectal anastomosis?

PubMed

Mitchem, J B; Stafford, C; Francone, T D; Roberts, P L; Schoetz, D J; Marcello, P W; Ricciardi, R

2018-02-01

An airtight anastomosis on intra-operative leak testing has been previously demonstrated to be associated with a lower risk of clinically significant postoperative anastomotic leak following left-sided colorectal anastomosis. However, to date, there is no consistently agreed upon method for management of an intra-operative anastomotic leak. Therefore, we powered a noninferiority study to determine whether suture repair alone was an appropriate strategy for the management of an intra-operative air leak. This is a retrospective cohort analysis of prospectively collected data from a tertiary care referral centre. We included all consecutive patients with left-sided colorectal or ileorectal anastomoses and evidence of air leak during intra-operative leak testing. Patients were excluded if proximal diversion was planned preoperatively, a pre-existing proximal diversion was present at the time of surgery or an anastomosis was ultimately unable to be completed. The primary outcome measure was clinically significant anastomotic leak, as defined by the Surgical Infection Study Group at 30 days. From a sample of 2360 patients, 119 had an intra-operative air leak during leak testing. Sixty-eight patients underwent suture repair alone and 51 underwent proximal diversion or anastomotic reconstruction. The clinically significant leak rate was 9% (6/68; 95% CI: 2-15%) in the suture repair alone arm and 0% (0/51) in the diversion or reconstruction arm. Suture repair alone does not meet the criteria for noninferiority for the management of intra-operative air leak during left-sided colorectal anastomosis. Further repair of intra-operative air leak by suture repair alone should be reconsidered given these findings. Colorectal Disease © 2017 The Association of Coloproctology of Great Britain and Ireland.

Capillary Leak Syndrome Following Snakebite Envenomation

PubMed Central

Udayabhaskaran, V.; Arun Thomas, E. T.; Shaji, Bhagya

2017-01-01

Capillary leak syndrome is a unique complication that follows Russell's viper envenomation. This syndrome has a very high fatality rate and is characterized by parotid swelling, chemosis, periorbital edema, hypotension, albuminuria, hypoalbuminemia, and hemoconcentration. This syndrome is frequently recognized from the southern parts of India, especially from the state of Kerala. It has been postulated that a vascular apoptosis inducing component of Russell's viper venom that is not neutralized by the commercially available anti-snake venom (ASV) is responsible for this complication as it occurs even after adequate doses of ASV administration in most cases. Acute kidney injury often requiring dialysis is invariably present in all patients because of reduced renal perfusion and ischemic acute tubular necrosis as a result of hypotension. Management mainly involves aggressive fluid resuscitation to maintain adequate tissue perfusion. There are no other proven effective treatment modalities, except a few reports of successful treatment with plasmapheresis. Methylprednisolone pulse therapy, terbutaline, aminophylline, and intravenous immunoglobulin are other treatment modalities tried. PMID:29142382

Postoperative esophageal leak management with the Polyflex esophageal stent.

PubMed

Freeman, Richard K; Ascioti, Anthony J; Wozniak, Thomas C

2007-02-01

Leak after esophageal anastomosis or perforation repair prolongs hospitalization, prevents oral hydration and nutrition, and can produce localized infection or sepsis. This investigation reviews our experience treating postoperative esophageal leaks with the Polyflex esophageal stent (Boston Scientific, Natick, Mass). Over a 30-month period, patients with a postoperative esophageal leak were treated with the Polyflex stent for leak occlusion. Leak occlusion was confirmed by means of esophagraphy. Patients were followed until their stent was removed and their esophageal leak had resolved. Twenty-one patients had 27 stents placed for leak occlusion after esophagectomy (n = 5), esophageal perforation (n = 5), surgical (n = 4) or endoscopic (n = 2) antireflux procedure, and esophageal diverticulectomy (n = 3) or myotomy (n = 2). The mean interval between surgical intervention and stent placement was 12 +/- 8 days (range, 3-31 days). Occlusion of the leak occurred in 20 patients. One patient experienced a dehiscence of the surgical esophageal perforation repair requiring esophageal diversion. Stent migration requiring repositioning (n = 3) or replacement (n = 4) occurred in 5 (24%) patients. Twenty (95%) stents were removed without residual leak (mean, 51 +/- 43 days; range, 15-175 days). One patient had a stricture after stent removal that required endoscopic dilatation. One patient in this series died. The Polyflex esophageal stent is an effective method for occluding a postoperative esophageal leak. It rapidly eliminates contamination of the mediastinum, pleura, and peritoneum; allows oral hydration and nutrition; and is easily removable. These stents also offer an appealing alternative to traditional esophageal diversion and subsequent reconstruction in patients with a persistent esophageal leak.

Successful endoscopic therapy of traumatic bile leaks.

PubMed

Spinn, Matthew P; Patel, Mihir K; Cotton, Bryan A; Lukens, Frank J

2013-01-01

Traumatic bile leaks often result in high morbidity and prolonged hospital stay that requires multimodality management. Data on endoscopic management of traumatic bile leaks are scarce. Our study objective was to evaluate the efficacy of the endoscopic management of a traumatic bile leak. We performed a retrospective case review of patients who were referred for endoscopic retrograde cholangiopancreatography (ERCP) after traumatic bile duct injury secondary to blunt (motor vehicle accident) or penetrating (gunshot) trauma for management of bile leaks at our tertiary academic referral center. Fourteen patients underwent ERCP for the management of a traumatic bile leak over a 5-year period. The etiology included blunt trauma from motor vehicle accident in 8 patients, motorcycle accident in 3 patients and penetrating injury from a gunshot wound in 3 patients. Liver injuries were grade III in 1 patient, grade IV in 10 patients, and grade V in 3 patients. All patients were treated by biliary stent placement, and the outcome was successful in 14 of 14 cases (100%). The mean duration of follow-up was 85.6 days (range 54-175 days). There were no ERCP-related complications. In our case review, endoscopic management with endobiliary stent placement was found to be successful and resulted in resolution of the bile leak in all 14 patients. Based on our study results, ERCP should be considered as first-line therapy in the management of traumatic bile leaks.

External detection and localization of well leaks in aquifer zones

NASA Astrophysics Data System (ADS)

Haas, Allan K.

This dissertation presents a new methodology for monitoring, detecting, and localizing shallow, aquifer zone leaks in oil and gas wells. The rationale for this type of leak detection is to close the knowledge gap associated with public claims of subsurface water resource contamination caused by the oil and gas industry. A knowledge gap exists because there is no data, one way or the other, that can definitively prove or deny the existence of subsurface leakage pathways in oil and gas wells, new, old or abandoned. This dissertation begins with an overview of existing and future oil and gas well leak detection methods, and then presents three published papers, each describing a different phenomena that can be exploited for leak monitoring, detection, localization, and damage extent determination. The first paper describes the direct detection and localization of a leak that was discovered during a laboratory based hydraulic fracturing experiment. The second paper describes the laboratory measured electrical response that occurs during two phase flow inside of porous media. The third paper describes the detection and tracking of a gravity driven salt plume leak in a freshwater test tank in the laboratory. the three geophysical approaches that are presented, when combined together, provide a new, powerful, external to the well method to monitor, detect, localize, and assess the damage from leaks in the drinking water protection zone of oil and gas wells. This is a capability that is not available in any other leak detection and localization method. This dissertation also presents a chapter of Science, Technology and Society (STS), and Science, and Technology Policy (STP) as a final fulfillment requirement of the SmartGeo Fellowship program, and the Science, Technology, Engineering, and Policy minor. This chapter introduces a new STS/STP concept concerning the after effects of knowledge boundary disputes. This new concept is called the residual footprints of knowledge

Locating air leaks in manned spacecraft using structure-borne noise.

PubMed

Holland, Stephen D; Chimenti, D E; Roberts, Ron; Strei, Michael

2007-06-01

All manned spacecraft are vulnerable to leaks generated by micrometeorite or debris impacts. Methods for locating such leaks using leak-generated, structure-borne ultrasonic noise are discussed and demonstrated. Cross-correlations of ultrasonic noise waveforms from a leak into vacuum are used to find the location of the leak. Four methods for sensing and processing leak noise have been developed and tested and each of these can be used to reveal the leak location. The methods, based on phased-array, distributed sensor, and dual sensor approaches, utilize the propagation patterns of guided ultrasonic Lamb waves in the spacecraft skin structure to find the source or direction of the leak noise. It is shown that each method can be used to successfully locate the leak to within a few millimeters on a 0.6-m2 aluminum plate. The relative merits of the four methods are discussed.

Spacecraft Leak Location Using Structure-Borne Noise

NASA Astrophysics Data System (ADS)

Reusser, R. S.; Chimenti, D. E.; Holland, S. D.; Roberts, R. A.

2010-02-01

Guided ultrasonic waves, generated by air escaping through a small hole, have been measured with an 8×8 piezoelectric phased-array detector. Rapid location of air leaks in a spacecraft skin, caused by high-speed collisions with small objects, is essential for astronaut survival. Cross correlation of all 64 elements, one pair at a time, on a diced PZT disc combined with synthetic aperture analysis determines the dominant direction of wave propagation. The leak location is triangulated by combining data from two or more detector. To optimize the frequency band selection for the most robust direction finding, noise-field measurements of a plate with integral stiffeners have been performed using laser Doppler velocimetry. We compare optical and acoustic measurements to analyze the influence of the PZT array detector and its mechanical coupling to the plate.

Distributed wireless sensing for methane leak detection technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klein, Levente; van Kesse, Theodor

Large scale environmental monitoring requires dynamic optimization of data transmission, power management, and distribution of the computational load. In this work, we demonstrate the use of a wireless sensor network for detection of chemical leaks on gas oil well pads. The sensor network consist of chemi-resistive and wind sensors and aggregates all the data and transmits it to the cloud for further analytics processing. The sensor network data is integrated with an inversion model to identify leak location and quantify leak rates. We characterize the sensitivity and accuracy of such system under multiple well controlled methane release experiments. It ismore » demonstrated that even 1 hour measurement with 10 sensors localizes leaks within 1 m and determines leak rate with an accuracy of 40%. This integrated sensing and analytics solution is currently refined to be a robust system for long term remote monitoring of methane leaks, generation of alarms, and tracking regulatory compliance.« less

Distributed wireless sensing for fugitive methane leak detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klein, Levente J.; van Kessel, Theodore; Nair, Dhruv

Large scale environmental monitoring requires dynamic optimization of data transmission, power management, and distribution of the computational load. In this work, we demonstrate the use of a wireless sensor network for detection of chemical leaks on gas oil well pads. The sensor network consist of chemi-resistive and wind sensors and aggregates all the data and transmits it to the cloud for further analytics processing. The sensor network data is integrated with an inversion model to identify leak location and quantify leak rates. We characterize the sensitivity and accuracy of such system under multiple well controlled methane release experiments. It ismore » demonstrated that even 1 hour measurement with 10 sensors localizes leaks within 1 m and determines leak rate with an accuracy of 40%. This integrated sensing and analytics solution is currently refined to be a robust system for long term remote monitoring of methane leaks, generation of alarms, and tracking regulatory compliance.« less

Distributed wireless sensing for fugitive methane leak detection

DOE PAGES

Klein, Levente J.; van Kessel, Theodore; Nair, Dhruv; ...

2017-12-11

Large scale environmental monitoring requires dynamic optimization of data transmission, power management, and distribution of the computational load. In this work, we demonstrate the use of a wireless sensor network for detection of chemical leaks on gas oil well pads. The sensor network consist of chemi-resistive and wind sensors and aggregates all the data and transmits it to the cloud for further analytics processing. The sensor network data is integrated with an inversion model to identify leak location and quantify leak rates. We characterize the sensitivity and accuracy of such system under multiple well controlled methane release experiments. It ismore » demonstrated that even 1 hour measurement with 10 sensors localizes leaks within 1 m and determines leak rate with an accuracy of 40%. This integrated sensing and analytics solution is currently refined to be a robust system for long term remote monitoring of methane leaks, generation of alarms, and tracking regulatory compliance.« less

Drain amylase aids detection of anastomotic leak after esophagectomy.

PubMed

Baker, Erin H; Hill, Joshua S; Reames, Mark K; Symanowski, James; Hurley, Susie C; Salo, Jonathan C

2016-04-01

Anastomotic leak following esophagectomy is associated with significant morbidity and mortality. As hospital length of stay decreases, the timely diagnosis of leak becomes more important. We evaluated CT esophagram, white blood count (WBC), and drain amylase levels in the early detection of anastomotic leak. The diagnostic performance of CT esophagram, drain amylase >800 IU/L, and WBC >12,000/µL within the first 10 days after surgery in predicting leak at any time after esophagectomy was calculated. Anastomotic leak occurred in 13 patients (13%). CT esophagram performed within 10 days of surgery diagnosed six of these leaks with a sensitivity of 0.54. Elevation in drain amylase level within 10 days of surgery diagnosed anastomotic leak with a sensitivity of 0.38. When the CT esophagram and drain amylase were combined, the sensitivity rose to 0.69 with a specificity of 0.98. WBC elevation had a sensitivity of 0.92, with a specificity of 0.34. Among 30 patients with normal drain amylase and a normal WBC, one developed an anastomotic leak. Drain amylase adds to the sensitivity of CT esophagram in the early detection of anastomotic leak. Selected patients with normal drain amylase levels and normal WBC may be able to safely forgo CT esophagram.

Anastomotic leak after colorectal resection: A population-based study of risk factors and hospital variation.

PubMed

Nikolian, Vahagn C; Kamdar, Neil S; Regenbogen, Scott E; Morris, Arden M; Byrn, John C; Suwanabol, Pasithorn A; Campbell, Darrell A; Hendren, Samantha

2017-06-01

Anastomotic leak is a major source of morbidity in colorectal operations and has become an area of interest in performance metrics. It is unclear whether anastomotic leak is associated primarily with surgeons' technical performance or explained better by patient characteristics and institutional factors. We sought to establish if anastomotic leak could serve as a valid quality metric in colorectal operations by evaluating provider variation after adjusting for patient factors. We performed a retrospective cohort study of colorectal resection patients in the Michigan Surgical Quality Collaborative. Clinically relevant patient and operative factors were tested for association with anastomotic leak. Hierarchical logistic regression was used to derive risk-adjusted rates of anastomotic leak. Of 9,192 colorectal resections, 244 (2.7%) had a documented anastomotic leak. The incidence of anastomotic leak was 3.0% for patients with pelvic anastomoses and 2.5% for those with intra-abdominal anastomoses. Multivariable analysis showed that a greater operative duration, male sex, body mass index >30 kg/m 2 , tobacco use, chronic immunosuppressive medications, thrombocytosis (platelet count >400 × 10 9 /L), and urgent/emergency operations were independently associated with anastomotic leak (C-statistic = 0.75). After accounting for patient and procedural risk factors, 5 hospitals had a significantly greater incidence of postoperative anastomotic leak. This population-based study shows that risk factors for anastomotic leak include male sex, obesity, tobacco use, immunosuppression, thrombocytosis, greater operative duration, and urgent/emergency operation; models including these factors predict most of the variation in anastomotic leak rates. This study suggests that anastomotic leak can serve as a valid metric that can identify opportunities for quality improvement. Copyright © 2017 Elsevier Inc. All rights reserved.

Study of Residual Gas Analyser (RGA) Response towards Known Leaks

NASA Astrophysics Data System (ADS)

Pathan, Firozkhan S.; Khan, Ziauddin; Semwal, Pratibha; George, Siju; Raval, Dilip C.; Thankey, Prashant L.; Manthena, Himabindu; Yuvakiran, Paravastu; Dhanani, Kalpesh R.

2012-11-01

Helium leak testing is the most versatile form of weld qualification test for any vacuum application. Almost every ultra-high vacuum (UHV) system utilizes this technique for insuring leak tightness for the weld joints as well as demountable joints. During UHV system under operational condition with many other integrated components, in-situ developed leaks identification becomes one of the prime aspect for maintaining the health of such system and for continuing the experiments onwards. Since online utilization of leak detector (LD) has many practical limitations, residual gas analyser (RGA) can be used as a potential instrument for online leak detection. For this purpose, a co-relation for a given leak rate between Leak Detector and RGA is experimentally established. This paper describes the experimental aspect and the relationship between leak detector and RGA.

Severe capillary leak syndrome after inner ear decompression sickness in a recreational scuba diver.

PubMed

Gempp, Emmanuel; Lacroix, Guillaume; Cournac, Jean-Marie; Louge, Pierre

2013-07-01

Post-decompression shock with plasma volume deficit is a very rare event that has been observed under extreme conditions of hypobaric and hyperbaric exposure in aviators and professional divers. We report a case of severe hypovolemic shock due to extravasation of plasma in a recreational scuba diver presenting with inner ear decompression sickness. Impaired endothelial function can lead to capillary leak with hemoconcentration and hypotension in severe cases. This report suggests that decompression-induced circulating bubbles may have triggered the endothelial damage, activating the classic inflammatory pathway of increased vascular permeability. This observation highlights the need for an accurate diagnosis of this potentially life-threatening condition at the initial presentation in the Emergency Department after a diving-related injury. An elevated hematocrit in a diver should raise the suspicion for the potential development of capillary leak syndrome requiring specific treatment using albumin infusion as primary fluid replacement. Copyright © 2013 Elsevier Inc. All rights reserved.

Conceptual apparatus for detecting leaks of nonconductive liquids

NASA Technical Reports Server (NTRS)

Walsh, G. D.

1968-01-01

Apparatus detects leaks at joints in lines carrying electrically nonconductive liquids. The proposed apparatus could include a panel that would give a visual or audible indication of a leak /to permit manual shutdown/ and/or an electromechanical actuator that would automatically cut off the flow when a leak occurs.

ISS Ammonia Leak Detection Through X-Ray Fluorescence

NASA Technical Reports Server (NTRS)

Camp, Jordan; Barthelmy, Scott; Skinner, Gerry

2013-01-01

Ammonia leaks are a significant concern for the International Space Station (ISS). The ISS has external transport lines that direct liquid ammonia to radiator panels where the ammonia is cooled and then brought back to thermal control units. These transport lines and radiator panels are subject to stress from micrometeorites and temperature variations, and have developed small leaks. The ISS can accommodate these leaks at their present rate, but if the rate increased by a factor of ten, it could potentially deplete the ammonia supply and impact the proper functioning of the ISS thermal control system, causing a serious safety risk. A proposed ISS astrophysics instrument, the Lobster X-Ray Monitor, can be used to detect and localize ISS ammonia leaks. Based on the optical design of the eye of its namesake crustacean, the Lobster detector gives simultaneously large field of view and good position resolution. The leak detection principle is that the nitrogen in the leaking ammonia will be ionized by X-rays from the Sun, and then emit its own characteristic Xray signal. The Lobster instrument, nominally facing zenith for its astrophysics observations, can be periodically pointed towards the ISS radiator panels and some sections of the transport lines to detect and localize the characteristic X-rays from the ammonia leaks. Another possibility is to use the ISS robot arm to grab the Lobster instrument and scan it across the transport lines and radiator panels. In this case the leak detection can be made more sensitive by including a focused 100-microampere electron beam to stimulate X-ray emission from the leaking nitrogen. Laboratory studies have shown that either approach can be used to locate ammonia leaks at the level of 0.1 kg/day, a threshold rate of concern for the ISS. The Lobster instrument uses two main components: (1) a microchannel plate optic (also known as a Lobster optic) that focuses the X-rays and directs them to the focal plane, and (2) a CCD (charge

Hydrogel sealant versus sutures to prevent fluid egress after cataract surgery.

PubMed

Masket, Samuel; Hovanesian, John A; Levenson, Jeffrey; Tyson, Farrell; Flynn, William; Endl, Michael; Majmudar, Parag A; Modi, Satish; Chu, Ralph; Raizman, Michael B; Lane, Stephen S; Kim, Terry

2014-12-01

To evaluate the effectiveness of a hydrogel sealant versus a suture in preventing fluid egress after wound leakage in cataract surgery. Twenty-four ophthalmic clinical practices in the United States. Prospective randomized parallel-arm controlled multicenter subject-masked study. Healthy patients having uneventful clear corneal incision (CCI) cataract surgery were eligible for the study. Spontaneous and provoked fluid egress from wounds was evaluated at the time of surgery using a calibrated force gauge. Eyes with leakage were randomized to receive a hydrogel sealant (Resure) or a nylon suture at the main incision site. Incision leakage was reevaluated 1, 3, 7, and 28 days postoperatively. Of 500 eyes, 488 had leakage at the time of cataract surgery. The leak was spontaneous in 244 cases (48.8%), and 488 (97.6%) of all incisions leaked with 1.0 ounce or less of applied force. After randomization, 12 (4.1%) of 295 eyes in the sealant group and 60 (34.1%) of 176 eyes in the suture group had wound leakage with provocation (P<.0001). The overall incidence of adverse ocular events was statistically significantly lower in the sealant group than in the suture group (P<.05). In this study, 97.6% of CCIs leaked after cataract surgery. The hydrogel sealant was safe and effective and better than a suture for the intraoperative management of CCIs with leakage as seen on Seidel testing and for the prevention of postoperative fluid egress. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Gastric fluid versus amniotic fluid analysis for the identification of intra-amniotic infection due to Ureaplasma species

PubMed Central

Kim, Sun Min; Romero, Roberto; Lee, JoonHo; Chaemsaithong, Piya; Docheva, Nikolina; Yoon, Bo Hyun

2017-01-01

Objective Early neonatal sepsis is often due to intra-amniotic infection. The stomach of the neonate contains fluid swallowed before and during delivery. The presence of bacteria as well as neutrophils detected by culture or Gram stain in the gastric fluid during the first day of life is suggestive of exposure to bacteria or inflammation. We undertook this study to determine the relationship between gastric fluid analysis and amniotic fluid obtained by transabdominal amniocentesis in the detection of Ureaplasma species, the most frequent microorganisms responsible for intra-amniotic infection. Materials and Methods The study population consisted of 100 singleton pregnant women who delivered preterm neonates (<35weeks) within 7 days of amniocentesis. Gastric fluid of newborns was obtained by nasogastric intubation on the day of birth. Amniotic fluid and gastric fluid were cultured for genital Mycoplasmas and polymerase chain reaction (PCR) for Ureaplasma species was performed. Intra-amniotic inflammation was defined as an elevated amniotic fluid matrix metalloproteinase-8 concentration (> 23ng/mL). Results 1) Ureaplasma species were detected by culture or PCR in 18% (18/100) of amniotic fluid samples and in 5% (5/100) of gastric fluid samples; 2) among the amniotic fluid cases positive for Ureaplasma species, these microorganisms were identified in 27.8% (5/18) of gastric fluid samples; 3) none of the cases negative for Ureaplasma species in the amniotic fluid were found to be positive for these microorganisms in the gastric fluid; 4) patients with amniotic fluid positive for Ureaplasma species but with gastric fluid negative for these microorganisms had a significantly higher rate of intra-amniotic inflammation, acute histologic chorioamnionitis, and neonatal death than those with both amniotic fluid and gastric fluid negative for Ureaplasma species; and 5) no significant differences were observed in the rate of intra-amniotic inflammation, acute histologic

Gastric fluid versus amniotic fluid analysis for the identification of intra-amniotic infection due to Ureaplasma species.

PubMed

Kim, Sun Min; Romero, Roberto; Lee, JoonHo; Chaemsaithong, Piya; Docheva, Nikolina; Yoon, Bo Hyun

2016-01-01

Early neonatal sepsis is often due to intra-amniotic infection. The stomach of the neonate contains fluid swallowed before and during delivery. The presence of bacteria as well as neutrophils detected by culture or Gram stain of the gastric fluid during the first day of life is suggestive of exposure to bacteria or inflammation. We undertook this study to determine the relationship between gastric fluid analysis and amniotic fluid obtained by transabdominal amniocentesis in the detection of Ureaplasma species, the most frequent microorganisms responsible for intra-amniotic infection. The study population consisted of 100 singleton pregnant women who delivered preterm neonates (<35 weeks) within 7 days of amniocentesis. Gastric fluid of newborns was obtained by nasogastric intubation on the day of birth. Amniotic fluid and gastric fluid were cultured for genital Mycoplasmas, and polymerase chain reaction (PCR) for Ureaplasma species was performed. Intra-amniotic inflammation was defined as an elevated amniotic fluid matrix metalloproteinase-8 concentration (>23 ng/mL). (1) Ureaplasma species were detected by culture or PCR in 18% (18/100) of amniotic fluid samples and in 5% (5/100) of gastric fluid samples; (2) among the amniotic fluid cases positive for Ureaplasma species, these microorganisms were identified in 27.8% (5/18) of gastric fluid samples; (3) none of the cases negative for Ureaplasma species in the amniotic fluid were found to be positive for these microorganisms in the gastric fluid; (4) patients with amniotic fluid positive for Ureaplasma species but with gastric fluid negative for these microorganisms had a significantly higher rate of intra-amniotic inflammation, acute histologic chorioamnionitis, and neonatal death than those with both amniotic fluid and gastric fluid negative for Ureaplasma species; and (5) no significant differences were observed in the rate of intra-amniotic inflammation, acute histologic chorioamnionitis, and neonatal death

What Is the Risk of Anastomotic Leak After Repeat Intestinal Resection in Patients With Crohn's Disease?

PubMed

Johnston, W Forrest; Stafford, Caitlin; Francone, Todd D; Read, Thomas E; Marcello, Peter W; Roberts, Patricia L; Ricciardi, Rocco

2017-12-01

Approximately half of Crohn's patients require intestinal resection, and many need repeat resections. The purpose of this study was to evaluate the increased risk of clinical anastomotic leak in patients with a history of previous intestinal resection undergoing repeat resection with anastomosis for Crohn's disease. This was a retrospective analysis of prospectively collected departmental data with 100% capture. The study was conducted at the department of colorectal surgery in a tertiary care teaching hospital between July 2007 and March 2016. A cohort of consecutive patients with Crohn's disease who were treated with intestinal resection and anastomosis, excluding patients with proximal fecal diversion, were included. The cohort was divided into 2 groups, those with no previous resection compared with those with previous resection. Clinical anastomotic leak within 30 days of surgery was measured. Of the 206 patients who met criteria, 83 patients had previous intestinal resection (40%). The 2 groups were similar in terms of patient factors, immune-suppressing medication use, and procedural factors. Overall, 20 clinical anastomotic leaks were identified (10% leak rate). There were 6 leaks (5%) detected in patients with no previous intestinal resection and 14 leaks (17%) detected in patients with a history of previous intestinal resection (p < 0.005). The OR of anastomotic leak in patients with Crohn's disease with previous resection compared with no previous resection was 3.5 (95% CI, 1.3-9.4). Patients with 1 previous resection (n = 53) had a leak rate of 13%, whereas patients with ≥2 previous resections (n = 30) had a leak rate of 23%. The number of previous resections correlated with increasing risk for clinical anastomotic leak (correlation coefficient = 0.998). This was a retrospective study with limited data to perform a multivariate analysis. Repeat intestinal resection in patients with Crohn's disease is associated with an increased rate of anastomotic

Joint properties of a tool machining process to guarantee fluid-proof abilities

NASA Astrophysics Data System (ADS)

Bataille, C.; Deltombe, R.; Jourani, A.; Bigerelle, M.

2017-12-01

This study addressed the impact of rod surface topography in contact with reciprocating seals. Rods were tooled with and without centreless grinding. All rods tooled with centreless grinding were fluid-proof, in contrast to rods tooled without centreless grinding that either had leaks or were fluid-proof. A method was developed to analyse the machining signature, and the software Mesrug™ was used in order to discriminate roughness parameters that can be used to characterize the sealing functionality. According to this surface roughness analysis, a fluid-proof rod tooled without centreless grinding presents aperiodic large plateaus, and the relevant roughness parameter for characterizing the sealing functionality is the density of summits S DS. Increasing the density of summits counteracts leakage, which may be because motif decomposition integrates three topographical components: circularity (perpendicular long-wave roughness), longitudinal waviness, and roughness thanks to the Wolf pruning algorithm. A 3D analytical contact model was applied to analyse the contact area of each type of sample with the seal surface. This model provides a leakage probability, and the results were consistent with the interpretation of the topographical analysis.

The Soil Microbial Response to a Massive Natural Gas Leak

NASA Astrophysics Data System (ADS)

Tavormina, P. L.; Newman, S.; Shen, L.; Connon, S. A.; Okumura, M.; Orphan, V. J.

2016-12-01

The 2015/2016 gas leak in the Porter Ranch community (Southern California) was the largest natural gas leak in US history. While considerable attention has focused on the amount of methane released to the atmosphere and the effects of other gas components on human well-being, less attention has been given to the response of soil microbes to this event. These microbes represent natural pathways for utilization of C1 compounds in soils and, possibly, untapped potential to remediate natural and anthropogenic gas emissions. We monitored onsite and background soil methane concentrations and microbial communities during and following the Porter Ranch gas leak. Soil core samples (25cm depth, collected twice monthly beginning in January 2016) were preserved for DNA, RNA, microscopic, stable isotope probing, and chromatographic methods. Simultaneously to coring, gas from soil pore spaces was collected for cavity ringdown spectroscopy to measure carbon dioxide, methane and ethane concentrations, and estimate corresponding isotopic values in carbon dioxide and methane. By pairing these measurements with high throughput sequencing, transcript analysis, and cultivation, we demonstrate discrete shifts in the total microbial community in surface (0 - 5 cm) and deep (20 - 25 cm) soils. Importantly, we find that methane consumption likely occurred in surface soils during and following the leak. The lineages most significantly correlated with elevated methane from the leak event were five orders of magnitude more abundant near the leak event in space and time, indicating a microbial bloom. These lineages are previously unrecognized members of Sphingomonadaceae, and they encode at least two biochemical pathways for methane oxidation. Cultivation of the first representative of this group now allows more detailed investigation into its capacity for microbially-mediated soil methane oxidation and mitigation.

Overview of MSFC's Applied Fluid Dynamics Analysis Group Activities

NASA Technical Reports Server (NTRS)

Garcia, Roberto; Griffin, Lisa; Williams, Robert

2002-01-01

This viewgraph report presents an overview of activities and accomplishments of NASA's Marshall Space Flight Center's Applied Fluid Dynamics Analysis Group. Expertise in this group focuses on high-fidelity fluids design and analysis with application to space shuttle propulsion and next generation launch technologies. Topics covered include: computational fluid dynamics research and goals, turbomachinery research and activities, nozzle research and activities, combustion devices, engine systems, MDA development and CFD process improvements.

Modulation of leak K(+) channel in hypoglossal motoneurons of rats by serotonin and/or variation of pH value.

PubMed

Xu, Xue-Feng; Tsai, Hao-Jan; Li, Lin; Chen, Yi-Fan; Zhang, Cheng; Wang, Guang-Fa

2009-08-25

The cloned TWIK-related acid-sensitive K(+) channel (TASK-1) is sensitive to the pH changes within physiological pH range (pK~7.4). Recently, the native TASK-1-like channel was suggested to be the main contributor to the background (or leak) K(+) conductance in the motoneurons of the brain stem. Serotonin (5-HT) and variation of pH value in perfused solution could modulate these currents. Here we aimed to examine the properties and modulation of the currents by serotonin or variation of pH value in hypoglossal motoneurons of rats. Transverse slices were prepared from the brainstem of neonatal Sprague-Dawley rats (postnatal days 7-8). Hypoglossal motoneurons were used for the study. The leak K(+) current (TASK-1-like current) and hyperpolarization-activated cationic current (I(h)) were recorded with the whole-cell patch-clamp technique. The results showed that these currents were inhibited by acidified artificial cerebrospinal fluid (ACSF, pH 6.0) and activated by alkalized ACSF (pH 8.5). 5-HT (10 mumol/L) significantly inhibited both leak K(+) current and I(h) with depolarization of membrane potential and the occurrence of oscillation and/or spikes. Bath application of Ketanserine, an antagonist of 5-HT₂ receptor, reversed or reduced the inhibitory effect of acidified solution on leak K(+) current and I(h). The results suggest that 5-HT₂ receptors mediate the effects of acidified media on leak K(+) current and I(h) in hypoglossal motoneurons.

49 CFR 230.64 - Leaks under lagging.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Steam Leaks § 230.64 Leaks under lagging. The steam locomotive owner and/or operator shall take out of...

40 CFR 63.1023 - Instrument and sensory monitoring for leaks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... leaks. 63.1023 Section 63.1023 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... (CONTINUED) National Emission Standards for Equipment Leaks-Control Level 2 Standards § 63.1023 Instrument and sensory monitoring for leaks. (a) Monitoring for leaks. The owner or operator of a regulated...

Leak detection by mass balance effective for Norman Wells line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liou, J.C.P.

Mass-balance calculations for leak detection have been shown as effective as a leading software system, in a comparison based on a major Canadian crude-oil pipeline. The calculations and NovaCorp`s Leakstop software each detected 4% (approximately) or greater leaks on Interprovincial Pipe Line (IPL) Inc.`s Norman Wells pipeline. Insufficient data exist to assess performances of the two methods for leaks smaller than 4%. Pipeline leak detection using such software-based systems are common. Their effectiveness is measured by how small and how quickly a leak can be detected. Algorithms used and measurement uncertainties determine leak detectability.

10 CFR 36.59 - Detection of leaking sources.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 1 2010-01-01 2010-01-01 false Detection of leaking sources. 36.59 Section 36.59 Energy... Irradiators § 36.59 Detection of leaking sources. (a) Each dry-source-storage sealed source must be tested for leakage at intervals not to exceed 6 months using a leak test kit or method approved by the Commission or...

40 CFR 65.104 - Instrument and sensory monitoring for leaks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... leaks. 65.104 Section 65.104 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Equipment Leaks § 65.104 Instrument and sensory monitoring for leaks. (a) Monitoring for leaks. The owner or operator of a regulated source subject to this...

Leak rates in sealed cells.

NASA Technical Reports Server (NTRS)

Frank, H. A.; Uchiyama, A. A.

1973-01-01

Water vapor loss rates were determined from simulated and imperfectly sealed alkaline cells in the vacuum environment. The observed rates were found to be in agreement with a semi-empirical equation employed in vacuum technology. Results thereby give support for using this equation for the prediction of loss rates of battery gases and vapors to the aerospace environment. On this basis it was shown how the equation can be applied to the solution of many heretofore unresolved questions regarding leaks in batteries. Among these are the maximum permissible leak size consistent with a given cell life or conversely the maximum life consistent with a given leak size. It was also shown that loss rates of these cells in the terrestrial environment are several orders of magnitude less than the corresponding loss rates in the aerospace environment.

Leak test adapter for containers

DOEpatents

Hallett, Brian H.; Hartley, Michael S.

1996-01-01

An adapter is provided for facilitating the charging of containers and leak testing penetration areas. The adapter comprises an adapter body and stem which are secured to the container's penetration areas. The container is then pressurized with a tracer gas. Manipulating the adapter stem installs a penetration plug allowing the adapter to be removed and the penetration to be leak tested with a mass spectrometer. Additionally, a method is provided for using the adapter.

40 CFR 63.1004 - Instrument and sensory monitoring for leaks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... leaks. 63.1004 Section 63.1004 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... (CONTINUED) National Emission Standards for Equipment Leaks-Control Level 1 § 63.1004 Instrument and sensory monitoring for leaks. (a) Monitoring for leaks. The owner or operator of a regulated source subject to this...

Overview af MSFC's Applied Fluid Dynamics Analysis Group Activities

NASA Technical Reports Server (NTRS)

Garcia, Roberto; Griffin, Lisa; Williams, Robert

2004-01-01

This paper presents viewgraphs on NASA Marshall Space Flight Center's Applied Fluid Dynamics Analysis Group Activities. The topics include: 1) Status of programs at MSFC; 2) Fluid Mechanics at MSFC; 3) Relevant Fluid Dynamics Activities at MSFC; and 4) Shuttle Return to Flight.

SPAR improved structure/fluid dynamic analysis capability

NASA Technical Reports Server (NTRS)

Oden, J. T.; Pearson, M. L.

1983-01-01

The capability of analyzing a coupled dynamic system of flowing fluid and elastic structure was added to the SPAR computer code. A method, developed and adopted for use in SPAR utilizes the existing assumed stress hybrid plan element in SPAR. An operational mode was incorporated in SPAR which provides the capability for analyzing the flaw of a two dimensional, incompressible, viscous fluid within rigid boundaries. Equations were developed to provide for the eventual analysis of the interaction of such fluids with an elastic solid.

Double Shell Tank AY-102 Radioactive Waste Leak Investigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Washenfelder, Dennis J.

2014-04-10

PowerPoint. The objectives of this presentation are to: Describe Effort to Determine Whether Tank AY-102 Leaked; Review Probable Causes of the Tank AY-102 Leak; and, Discuss Influence of Leak on Hanford’s Double-Shell Tank Integrity Program.

Spectral luminescence analysis of amniotic fluid

NASA Astrophysics Data System (ADS)

Slobozhanina, Ekaterina I.; Kozlova, Nataly M.; Kasko, Leonid P.; Mamontova, Marina V.; Chernitsky, Eugene A.

1997-12-01

It is shown that the amniotic fluid has intensive ultra-violet luminescence caused by proteins. Along with it amniotic fluid radiated in the field of 380 - 650 nm with maxima at 430 - 450 nm and 520 - 560 nm. The first peak of luminescence ((lambda) exc equals 350 nm; (lambda) em equals 430 - 440 nm) is caused (most probably) by the presence in amniotic fluid of some hormones, NADH2 and NADPH2. A more long-wave component ((lambda) exc equals 460 nm; (lambda) em equals 520 - 560 nm) is most likely connected with the presence in amniotic fluid pigments (bilirubin connected with protein and other). It is shown that intensity and maximum of ultra-violet luminescence spectra of amniotic fluid in normality and at pathology are identical. However both emission spectra and excitation spectra of long-wave ((lambda) greater than 450 nm) luminescence of amniotic fluid from pregnant women with such prenatal abnormal developments of a fetus as anencephaly and spina bifida are too long-wave region in comparison with the norm. Results of research testify that spectral luminescent analysis of amniotic fluid can be used for screening of malformations of the neural tube. It is very difficult for a practical obstetrician to reveal pregnant women with a high risk of congenital malformations of the fetus. Apart from ultrasonic examination, cytogenetic examination of amniotic fluid and defumination of concentrations of alpha-fetoprotein and acetylcholin-esterases in the amniotic fluid and blood plasma are the most widely used diagnostic approaches. However, biochemical and cytogenetic diagnostic methods are time-consuming. In the present work spectral luminescence properties of the amniotic fluid are investigated to determine spectral parameters that can be used to reveal pregnant women with a high risk of congenital malformations of their offsprings.

40 CFR 63.1024 - Leak repair.

Code of Federal Regulations, 2012 CFR

2012-07-01

... light liquid service. The leak identification on a valve in gas/vapor or light liquid service may be... that monitoring. The leak identification on a connector in gas/vapor or light liquid service may be... or light liquid service that is subject to the provisions of § 63.1027(b)(3)(iv), may be removed...

40 CFR 63.1024 - Leak repair.

Code of Federal Regulations, 2011 CFR

2011-07-01

... light liquid service. The leak identification on a valve in gas/vapor or light liquid service may be... that monitoring. The leak identification on a connector in gas/vapor or light liquid service may be... or light liquid service that is subject to the provisions of § 63.1027(b)(3)(iv), may be removed...

40 CFR 63.1024 - Leak repair.

Code of Federal Regulations, 2013 CFR

2013-07-01

... light liquid service. The leak identification on a valve in gas/vapor or light liquid service may be... that monitoring. The leak identification on a connector in gas/vapor or light liquid service may be... or light liquid service that is subject to the provisions of § 63.1027(b)(3)(iv), may be removed...

40 CFR 63.1024 - Leak repair.

Code of Federal Regulations, 2014 CFR

2014-07-01

... light liquid service. The leak identification on a valve in gas/vapor or light liquid service may be... that monitoring. The leak identification on a connector in gas/vapor or light liquid service may be... or light liquid service that is subject to the provisions of § 63.1027(b)(3)(iv), may be removed...

Generalized Fluid System Simulation Program (GFSSP) Version 6 - General Purpose Thermo-Fluid Network Analysis Software

NASA Technical Reports Server (NTRS)

Majumdar, Alok; Leclair, Andre; Moore, Ric; Schallhorn, Paul

2011-01-01

GFSSP stands for Generalized Fluid System Simulation Program. It is a general-purpose computer program to compute pressure, temperature and flow distribution in a flow network. GFSSP calculates pressure, temperature, and concentrations at nodes and calculates flow rates through branches. It was primarily developed to analyze Internal Flow Analysis of a Turbopump Transient Flow Analysis of a Propulsion System. GFSSP development started in 1994 with an objective to provide a generalized and easy to use flow analysis tool for thermo-fluid systems.

Leak test fixture and method for using same

DOEpatents

Hawk, Lawrence S.

1976-01-01

A method and apparatus are provided which are especially useful for leak testing seams such as an end closure or joint in an article. The test does not require an enclosed pressurized volume within the article or joint section to be leak checked. A flexible impervious membrane is disposed over an area of the seamed surfaces to be leak checked and sealed around the outer edges. A preselected vacuum is applied through an opening in the membrane to evacuate the area between the membrane and the surface being leak checked to essentially collapse the membrane to conform to the article surface or joined adjacent surfaces. A pressure differential is concentrated at the seam bounded by the membrane and only the seam experiences a pressure differential as air or helium molecules are drawn into the vacuum system through a leak in the seam. A helium detector may be placed in a vacuum exhaust line from the membrane to detect the helium. Alternatively, the vacuum system may be isolated at a preselected pressure and leaks may be detected by a subsequent pressure increase in the vacuum system.

Design of a leak detection device for marine airtight container

NASA Astrophysics Data System (ADS)

Li, Yuan; Zhu, Faxin; Lu, Jinshu; Li, Yule; Wu, Wenfeng; Zhang, Jianwei; Qin, Beichen

2018-04-01

The ship airtight container as the research object, according to the tightness of the traditional detection methods of sealed container from the shortcomings of the design of modern ship sealed container leak detection device based on the requirements of the use of AutoCAD to design a ship leakage detection device using airtight container, and introduces its working principle and main components. Finally, from the aspects of technology, structure, operation and economy, the feasibility analysis of the leak detection device for marine airtight container is designed, and it is concluded that the device has the advantages of simple operation, short detection time, easy maintenance and cost control, and has high feasibility.

Operational Philosophy Concerning Manned Spacecraft Cabin Leaks

NASA Technical Reports Server (NTRS)

DeSimpelaere, Edward

2011-01-01

The last thirty years have seen the Space Shuttle as the prime United States spacecraft for manned spaceflight missions. Many lessons have been learned about spacecraft design and operation throughout these years. Over the next few decades, a large increase of manned spaceflight in the commercial sector is expected. This will result in the exposure of commercial crews and passengers to many of the same risks crews of the Space Shuttle have encountered. One of the more dire situations that can be encountered is the loss of pressure in the habitable volume of the spacecraft during on orbit operations. This is referred to as a cabin leak. This paper seeks to establish a general cabin leak response philosophy with the intent of educating future spacecraft designers and operators. After establishing a relative definition for a cabin leak, the paper covers general descriptions of detection equipment, detection methods, and general operational methods for management of a cabin leak. Subsequently, all these items are addressed from the perspective of the Space Shuttle Program, as this will be of the most value to future spacecraft due to similar operating profiles. Emphasis here is placed upon why and how these methods and philosophies have evolved to meet the Space Shuttle s needs. This includes the core ideas of: considerations of maintaining higher cabin pressures vs. lower cabin pressures, the pros and cons of a system designed to feed the leak with gas from pressurized tanks vs. using pressure suits to protect against lower cabin pressures, timeline and consumables constraints, re-entry considerations with leaks of unknown origin, and the impact the International Space Station (ISS) has had to the standard Space Shuttle cabin leak response philosophy. This last item in itself includes: procedural management differences, hardware considerations, additional capabilities due to the presence of the ISS and its resource, and ISS docking/undocking considerations with a

Linear and nonlinear analysis of fluid slosh dampers

NASA Astrophysics Data System (ADS)

Sayar, B. A.; Baumgarten, J. R.

1982-11-01

A vibrating structure and a container partially filled with fluid are considered coupled in a free vibration mode. To simplify the mathematical analysis, a pendulum model to duplicate the fluid motion and a mass-spring dashpot representing the vibrating structure are used. The equations of motion are derived by Lagrange's energy approach and expressed in parametric form. For a wide range of parametric values the logarithmic decrements of the main system are calculated from theoretical and experimental response curves in the linear analysis. However, for the nonlinear analysis the theoretical and experimental response curves of the main system are compared. Theoretical predictions are justified by experimental observations with excellent agreement. It is concluded finally that for a proper selection of design parameters, containers partially filled with viscous fluids serve as good vibration dampers.

Supercritical fluid chromatography for lipid analysis in foodstuffs.

PubMed

Donato, Paola; Inferrera, Veronica; Sciarrone, Danilo; Mondello, Luigi

2017-01-01

The task of lipid analysis has always challenged separation scientists, and new techniques in chromatography were often developed for the separation of lipids; however, no single technique or methodology is yet capable of affording a comprehensive screening of all lipid species and classes. This review acquaints the role of supercritical fluid chromatography within the field of lipid analysis, from the early developed capillary separations based on pure CO 2 , to the most recent techniques employing packed columns under subcritical conditions, including the niche multidimensional techniques using supercritical fluids in at least one of the separation dimensions. A short history of supercritical fluid chromatography will be introduced first, from its early popularity in the late 1980s, to the sudden fall and oblivion until the last decade, experiencing a regain of interest within the chromatographic community. Afterwards, the subject of lipid nomenclature and classification will be briefly dealt with, before discussing the main applications of supercritical fluid chromatography for food analysis, according to the specific class of lipids. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Definition and classification of chyle leak after pancreatic operation: A consensus statement by the International Study Group on Pancreatic Surgery.

PubMed

Besselink, Marc G; van Rijssen, L Bengt; Bassi, Claudio; Dervenis, Christos; Montorsi, Marco; Adham, Mustapha; Asbun, Horacio J; Bockhorn, Maximillian; Strobel, Oliver; Büchler, Markus W; Busch, Olivier R; Charnley, Richard M; Conlon, Kevin C; Fernández-Cruz, Laureano; Fingerhut, Abe; Friess, Helmut; Izbicki, Jakob R; Lillemoe, Keith D; Neoptolemos, John P; Sarr, Michael G; Shrikhande, Shailesh V; Sitarz, Robert; Vollmer, Charles M; Yeo, Charles J; Hartwig, Werner; Wolfgang, Christopher L; Gouma, Dirk J

2017-02-01

Recent literature suggests that chyle leak may complicate up to 10% of pancreatic resections. Treatment depends on its severity, which may include chylous ascites. No international consensus definition or grading system of chyle leak currently is available. The International Study Group on Pancreatic Surgery, an international panel of pancreatic surgeons working in well-known, high-volume centers, reviewed the literature and worked together to establish a consensus on the definition and classification of chyle leak after pancreatic operation. Chyle leak was defined as output of milky-colored fluid from a drain, drain site, or wound on or after postoperative day 3, with a triglyceride content ≥110 mg/dL (≥1.2 mmol/L). Three different grades of severity were defined according to the management needed: grade A, no specific intervention other than oral dietary restrictions; grade B, prolongation of hospital stay, nasoenteral nutrition with dietary restriction, total parenteral nutrition, octreotide, maintenance of surgical drains, or placement of new percutaneous drains; and grade C, need for other more invasive in-hospital treatment, intensive care unit admission, or mortality. This classification and grading system for chyle leak after pancreatic resection allows for comparison of outcomes between series. As with the other the International Study Group on Pancreatic Surgery consensus statements, this classification should facilitate communication and evaluation of different approaches to the prevention and treatment of this complication. Copyright © 2016 Elsevier Inc. All rights reserved.

Importance of limiting hohlraum leaks at cryogenic temperatures on NIF targets

DOE PAGES

Bhandarkar, Suhas; Teslich, Nick; Haid, Ben; ...

2017-08-18

Inertial confinement fusion targets are complex systems designed to allow fine control of temperature and pressure for making precise spherical ice layers of hydrogen isotopes at cryogenic temperatures. We discuss the various technical considerations for a maximum leak rate based on heat load considerations. This maximum flow rate turns out to bemore » $$5\\times 10^{-6}$$ standard cc per second, which can be caused by an orifice less than half a micron in diameter. This makes the identification of the location and resolution of the leak a significant challenge. To illustrate this, we showcase one example of a peculiar failure mode that appeared suddenly but persisted whereby target production yield was severely lowered. Identification of the leak source and the root cause requires very careful analysis of multiple thermomechanical aspects to ensure that the end solution is indeed the right remedy and is robust.« less

Fibrin glue as agent for sealing corneal and conjunctival wound leaks.

PubMed

Scalcione, C; Ortiz-Vaquerizas, D; Said, D G; Dua, H S

2018-02-01

PurposeTo describe a novel use of fibrin glue in managing leaking blebs and leaking wounds following trauma or surgery.MethodsInterventional case series.ResultsWe report eight patients, including three where intra-operative or immediate post-penetrating keratoplasty recalcitrant leaks from the graft-host junction and/or openings created by the needle pass, were noted. All three had thin recipient beds in the sector of leak. This was managed by intra-cameral injection of fibrin glue in the affected quadrant. This stopped the leak and allowed the defect to heal. One patient of Descemets-stripping-endothelial-keratoplasty had leak from the surgical wound, which was also sealed with fibrin glue. Two patients with leaking glaucoma-surgery-related blebs were treated with intra-bleb injection of fibrin glue to stop the leak. One patient with a penetrating corneal injury with a metal wire had a brisk leak upon removal of the wire. This was sealed with fibrin glue. Another patient of chemical burn with spontaneous leaks was managed by glue injection in the perforations. Transient rise of intraocular pressure in one patient with a leaking bleb was the only adverse event recorded.ConclusionThis novel adaptation of the application of fibrin glue can help to deal with persistent intra-operative, post-operative and traumatic aqueous and air leaks.

Presidential Leaks: Rhetoric and Mediated Political Knowledge.

ERIC Educational Resources Information Center

Erickson, Keith V.

1989-01-01

Argues that presidential leaks constitute rhetorical acts, enabling administrations to exercise a variety of rhetorically potent options not afforded by the public forum. Proposes a typology of presidential leaks and analyzes their rhetorical functions, benefits, and liabilities. (MM)

Analysis of Skylab fluid mechanics science demonstrations

NASA Technical Reports Server (NTRS)

Tegart, J. R.; Butz, J. R.

1975-01-01

The results of the data reduction and analysis of the Skylab fluid mechanics demonstrations are presented. All the fluid mechanics data available from the Skylab missions were identified and surveyed. The significant fluid mechanics phenomena were identified and reduced to measurable quantities wherever possible. Data correlations were performed using existing theories. Among the phenomena analyzed were: static low-g interface shapes, oscillation frequency and damping of a liquid drop, coalescence, rotating drop, liquid films and low-g ice melting. A survey of the possible applications of the results was made and future experiments are recommended.

Treatment of air leak in polytrauma patients with blunt chest injury.

PubMed

Halat, Gabriel; Negrin, Lukas L; Chrysou, Konstantina; Hoksch, Beatrix; Schmid, Ralph A; Kocher, Gregor J

2017-09-01

Precise diagnostics and an adequate therapeutic approach are mandatory in the treatment of air leak in polytrauma patients with blunt chest trauma. The aim of this study was to evaluate the incidence, characteristics, and management of air leak following this injury pattern. Data from 110 polytrauma patients was collected retrospectively. Fifty-four patients received initial treatment by chest tube placement for pneumothorax. These patients were classified into two groups, one with severe air leak and one with minor air leak. An evaluation of injury pattern, chest wall injuries in particular, duration of air leak, reason for drainage maintenance in place, hospital length of stay, ICU stay, ventilator duration, type of treatment, and the delay to surgical intervention was performed. Whereas 4 patients showed severe air leak and were subsequently scheduled for timely surgical intervention, the remaining 50 patients only showed minor air leak. Only 7 patients with minor air leak suffered from prolonged air leak (>5days), which spontaneously resolved in all of them after a mean duration of 7.7days (range 6-12days). Absence of a prolonged air leak resulted in a shorter length of stay and a shorter duration of mechanical ventilation, although no statistical significance was observed. Early spontaneous cessation of most minor air leaks as well as early surgical intervention for severe air leak lead to very satisfactory patient outcomes with a relatively short hospital stay in our patients. We therefore advocate early surgery for lacerations of the pulmonary parenchyma resulting in severe air leak, whereas minor air leaks can usually be treated conservatively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Air leak after lung resection: pathophysiology and patients' implications.

PubMed

Pompili, Cecilia; Miserocchi, Giuseppe

2016-02-01

Protocols for the management of air leaks are critical aspects in the postoperative course of patients following lung resections. Many investigations in the last decade are focusing on the chest tube modalities or preventative measures, however, little is known about the pathophysiology of air leak and the patient perception of this common complication. This review concentrates on understanding the reasons why a pulmonary parenchyma may start to leak or an air leak may be longer than others. Experimental works support the notion that lung overdistension may favor air leak. These studies may represent the basis of future investigations. Furthermore, the standardization of nomenclature in the field of pleural space management and the creation of novel air leak scoring systems have contributed to improve the knowledge among thoracic surgeons and facilitate the organization of trials on this matter. We tried to summarize available evidences about the patient perception of a prolonged air leak and about what would be useful for them in order to prevent worsening of their quality of life. Future investigations are warranted to better understand the pathophysiologic mechanisms responsible of prolonged air leak in order to define tailored treatments and protocols. Improving the care at home with web-based telemonitoring or real time connected chest drainage may in a future improve the quality of life of the patients experience this complication and also enhance hospital finances.

Air leak after lung resection: pathophysiology and patients’ implications

PubMed Central

Miserocchi, Giuseppe

2016-01-01

Protocols for the management of air leaks are critical aspects in the postoperative course of patients following lung resections. Many investigations in the last decade are focusing on the chest tube modalities or preventative measures, however, little is known about the pathophysiology of air leak and the patient perception of this common complication. This review concentrates on understanding the reasons why a pulmonary parenchyma may start to leak or an air leak may be longer than others. Experimental works support the notion that lung overdistension may favor air leak. These studies may represent the basis of future investigations. Furthermore, the standardization of nomenclature in the field of pleural space management and the creation of novel air leak scoring systems have contributed to improve the knowledge among thoracic surgeons and facilitate the organization of trials on this matter. We tried to summarize available evidences about the patient perception of a prolonged air leak and about what would be useful for them in order to prevent worsening of their quality of life. Future investigations are warranted to better understand the pathophysiologic mechanisms responsible of prolonged air leak in order to define tailored treatments and protocols. Improving the care at home with web-based telemonitoring or real time connected chest drainage may in a future improve the quality of life of the patients experience this complication and also enhance hospital finances. PMID:26941970

Slip analysis of squeezing flow using doubly stratified fluid

NASA Astrophysics Data System (ADS)

Ahmad, S.; Farooq, M.; Javed, M.; Anjum, Aisha

2018-06-01

The non-isothermal flow is modeled and explored for squeezed fluid. The influence of velocity, thermal and solutal slip effects on transport features of squeezed fluid are analyzed through Darcy porous channel when fluid is moving due to squeezing of upper plate towards the stretchable lower plate. Dual stratification effects are illustrated in transport equations. A similarity analysis is performed and reduced governing flow equations are solved using moderated and an efficient convergent approach i.e. Homotopic technique. The significant effects of physical emerging parameters on flow velocity, temperature and fluid concentration are reporting through various plots. Graphical explanations for drag force, Nusselt and Sherwood numbers are stated and examined. The results reveal that minimum velocity field occurs near the plate, whereas it increases far away from the plate for strong velocity slip parameter. Furthermore, temperature and fluid concentration significantly decreases with increased slip effects. The current analysis is applicable in some advanced technological processes and industrial fluid mechanics.

10 CFR 36.59 - Detection of leaking sources.

Code of Federal Regulations, 2013 CFR

2013-01-01

... alarm set-point to a higher level if necessary to operate the pool water purification system to clean up... certificate from a transferor that leak test has been done within the 6 months before the transfer. Water from... either by using a radiation monitor on a pool water circulating system or by analysis of a sample of pool...

10 CFR 36.59 - Detection of leaking sources.

Code of Federal Regulations, 2012 CFR

2012-01-01

... alarm set-point to a higher level if necessary to operate the pool water purification system to clean up... certificate from a transferor that leak test has been done within the 6 months before the transfer. Water from... either by using a radiation monitor on a pool water circulating system or by analysis of a sample of pool...

10 CFR 36.59 - Detection of leaking sources.

Code of Federal Regulations, 2011 CFR

2011-01-01

... alarm set-point to a higher level if necessary to operate the pool water purification system to clean up... certificate from a transferor that leak test has been done within the 6 months before the transfer. Water from... either by using a radiation monitor on a pool water circulating system or by analysis of a sample of pool...

10 CFR 36.59 - Detection of leaking sources.

Code of Federal Regulations, 2014 CFR

2014-01-01

... alarm set-point to a higher level if necessary to operate the pool water purification system to clean up... certificate from a transferor that leak test has been done within the 6 months before the transfer. Water from... either by using a radiation monitor on a pool water circulating system or by analysis of a sample of pool...

40 CFR 86.328-79 - Leak checks.

Code of Federal Regulations, 2013 CFR

2013-07-01

... flows may be used to estimate the in-use flow rates. (3) The sample probe and the connection between the sample probe and valve V2 (Figure D79-1) may be excluded from the leak check. (b) Pressure side leak...

40 CFR 86.328-79 - Leak checks.

Code of Federal Regulations, 2012 CFR

2012-07-01

... flows may be used to estimate the in-use flow rates. (3) The sample probe and the connection between the sample probe and valve V2 (Figure D79-1) may be excluded from the leak check. (b) Pressure side leak...

40 CFR 86.328-79 - Leak checks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... flows may be used to estimate the in-use flow rates. (3) The sample probe and the connection between the sample probe and valve V2 (Figure D79-1) may be excluded from the leak check. (b) Pressure side leak...

40 CFR 86.328-79 - Leak checks.

Code of Federal Regulations, 2011 CFR

2011-07-01

... flows may be used to estimate the in-use flow rates. (3) The sample probe and the connection between the sample probe and valve V2 (Figure D79-1) may be excluded from the leak check. (b) Pressure side leak...

Flood Syndrome: Spontaneous Umbilical Hernia Rupture Leaking Ascitic Fluid-A Case Report.

PubMed

Nguyen, Emilie T; Tudtud-Hans, Leah A

2017-01-01

We report a rare case of Flood syndrome, which is a spontaneous rupture of an umbilical hernia. A 42-year-old man with decompensated hepatitis C and alcoholic cirrhosis complicated by ascites and esophageal varices presented with 1 day of ascitic fluid drainage after rupture of a preexisting umbilical hernia associated with diffuse abdominal pain and tenderness. A pigtail drain was placed in the right upper abdominal quadrant to decrease fluid drainage from the abdominal wall defect, allowing it to heal naturally. The spontaneous rupture of an umbilical hernia in our patient highlights a rare complication with high mortality rates and stresses the challenge of treatment that falls in the area between medical and surgical management.

Measuring Pinhole Leaks - A Novel Method

NASA Technical Reports Server (NTRS)

Dunn, Carol Anne

2009-01-01

Both of the shuttle pads have one of these large liquid hydrogen tanks and the Shuttle program is currently using both pads. However, just recently, there has been increasing concerns over possible air leaks from the outside into the evacuated region. A method to detect leaks involving measuring the change in the boil-off rate of the liquid hydrogen in the tank.

INNOVATIVE ACOUSTIC SENSOR TECHNOLOGIES FOR LEAK DETECTION IN CHALLENGING PIPE TYPES

DTIC Science & Technology

2016-12-30

through focused acoustic surveys that are typically conducted at the correlated location prior to marking the leak location. All three technologies were...shift” survey with cross- correlation Echologics LeakFinderRTT M Field survey of leak signatures. Recommended every 3-5 years Contractor...cross- correlation features to detect and pinpoint leaks in challenging pipe types, as well as metallic pipes. 15. SUBJECT TERMS Leak detection

Remote Leak Detection: Indirect Thermal Technique

NASA Technical Reports Server (NTRS)

Clements, Sandra

2002-01-01

Remote sensing technologies are being considered for efficient, low cost gas leak detection. Eleven specific techniques have been identified for further study and evaluation of several of these is underway. The Indirect Thermal Technique is one of the techniques that is being explored. For this technique, an infrared camera is used to detect the temperature change of a pipe or fitting at the site of a gas leak. This temperature change is caused by the change in temperature of the gas expanding from the leak site. During the 10-week NFFP program, the theory behind the technique was further developed, experiments were performed to determine the conditions for which the technique might be viable, and a proof-of-concept system was developed and tested in the laboratory.

Elevated body mass index and risk of postoperative CSF leak following transsphenoidal surgery

PubMed Central

Dlouhy, Brian J.; Madhavan, Karthik; Clinger, John D.; Reddy, Ambur; Dawson, Jeffrey D.; O’Brien, Erin K.; Chang, Eugene; Graham, Scott M.; Greenlee, Jeremy D. W.

2012-01-01

Object Postoperative CSF leakage can be a serious complication after a transsphenoidal surgical approach. An elevated body mass index (BMI) is a significant risk factor for spontaneous CSF leaks. However, there is no evidence correlating BMI with postoperative CSF leak after transsphenoidal surgery. The authors hypothesized that patients with elevated BMI would have a higher incidence of CSF leakage complications following transsphenoidal surgery. Methods The authors conducted a retrospective review of 121 patients who, between August 2005 and March 2010, underwent endoscopic endonasal transsphenoidal surgeries for resection of primarily sellar masses. Patients requiring extended transsphenoidal approaches were excluded. A multivariate statistical analysis was performed to investigate the association of BMI and other risk factors with postoperative CSF leakage. Results In 92 patients, 96 endonasal endoscopic transsphenoidal surgeries were performed that met inclusion criteria. Thirteen postoperative leaks occurred and required subsequent treatment, including lumbar drainage and/or reoperation. The average BMI of patients with a postoperative CSF leak was significantly greater than that in patients with no postoperative CSF leak (39.2 vs 32.9 kg/m2, p = 0.006). Multivariate analyses indicate that for every 5-kg/m2 increase in BMI, patients undergoing a transsphenoidal approach for a primarily sellar mass have 1.61 times the odds (95% CI 1.10–2.29, p = 0.016, by multivariate logistic regression) of having a postoperative CSF leak. Conclusions Elevated BMI is an independent predictor of postoperative CSF leak after an endonasal endoscopic transsphenoidal approach. The authors recommend that patients with BMI greater than 30 kg/m2 have meticulous sellar reconstruction at surgery and close monitoring postoperatively. PMID:22443502

1999 Leak Detection and Monitoring and Mitigation Strategy Update

DOE Office of Scientific and Technical Information (OSTI.GOV)

OHL, P.C.

This document is a complete revision of WHC-SD-WM-ES-378, Rev 1. This update includes recent developments in Leak Detection, Leak Monitoring, and Leak Mitigation technologies, as well as, recent developments in single-shell tank retrieval technologies. In addition, a single-shell tank retrieval release protection strategy is presented.

Leak Detection and Location Technology Assessment for Aerospace Applications

NASA Technical Reports Server (NTRS)

Wilson, William C.; Coffey, Neil C.; Madaras, Eric I.

2008-01-01

Micro Meteoroid and Orbital Debris (MMOD) and other impacts can cause leaks in the International Space Station and other aerospace vehicles. The early detection and location of leaks is paramount to astronaut safety. Therefore this document surveys the state of the art in leak detection and location technology for aerospace vehicles.

A new tool for the rapid remote detection of leaks from subsea pipelines during remotely operated vehicle inspections

NASA Astrophysics Data System (ADS)

McStay, D.; McIlroy, J.; Forte, A.; Lunney, F.; Greenway, T.; Thabeth, K.; Dean, G.

2005-06-01

A new 2000 m depth rated subsea sensor that can effectively, rapidly and remotely detect leaks of fluorescein dye, leak detection chemicals and hydraulic fluids from underwater structures is reported. The system utilizes ultra-bright LED technology to project a structured beam of light, at a wavelength suitable to excite the fluorescence of the target material, into the water column. The resultant fluorescence is collected and digital signal processing used to extract the intensity. The system is capable of detecting ppm concentrations of fluorescein at a range of 2.5 m in water in real time. The ability to stand-off from subsea structures, while rapidly detecting the chemicals makes the system highly suited to subsea leak inspections with remotely operated vehicles or autonomous underwater vehicles, as it allows the vehicles to be flown quickly and safely over the structure to be inspected. This increases both the speed and effectiveness of the inspection. The remote detection capability is also highly effective for probing complex underwater structures. The system has been successfully used in real subsea survey applications and has been found to be effective, user friendly and to dramatically reduce inspection times and hence costs.

Scanning, standoff TDLAS leak imaging and quantification

NASA Astrophysics Data System (ADS)

Wainner, Richard T.; Aubut, Nicholas F.; Laderer, Matthew C.; Frish, Michael B.

2017-05-01

This paper reports a novel quantitative gas plume imaging tool, based on active near-infrared Backscatter Tunable Diode Laser Absorption Spectroscopy (b-TDLAS) technology, designed for upstream natural gas leak applications. The new tool integrates low-cost laser sensors with video cameras to create a highly sensitive gas plume imager that also quantifies emission rate, all in a lightweight handheld ergonomic package. It is intended to serve as a lower-cost, higherperformance, enhanced functionality replacement for traditional passive non-quantitative mid-infrared Optical Gas Imagers (OGI) which are utilized by industry to comply with natural gas infrastructure Leak Detection and Repair (LDAR) requirements. It addresses the need for reliable, robust, low-cost sensors to detect and image methane leaks, and to quantify leak emission rates, focusing on inspections of upstream oil and gas operations, such as well pads, compressors, and gas plants. It provides: 1) Colorized quantified images of path-integrated methane concentration. The images depict methane plumes (otherwise invisible to the eye) actively interrogated by the laser beam overlaid on a visible camera image of the background. The detection sensitivity exceeds passive OGI, thus simplifying the manual task of leak detection and location; and 2) Data and algorithms for using the quantitative information gathered by the active detection technique to deduce plume flux (i.e. methane emission rate). This key capability will enable operators to prioritize leak repairs and thereby minimize the value of lost product, as well as to quantify and minimize greenhouse gas emissions, using a tool that meets EPA LDAR imaging equipment requirements.

Lymphangiography in the Diagnosis and Localization of Various Chyle Leaks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deso, Steve; Ludwig, Benjamin; Kabutey, Nii-Kabu

2012-02-15

Purpose: Chyle leaks are rare entities infrequently encountered by most physicians. However, large centers providing advanced surgical care are inevitably confronted with chyle leaks as a complication of surgery, an extension of disease, or as a primary disorder. Regardless of the etiology, proper diagnosis and localization are paramount in the management of any chyle leak. Materials and Methods: Here we present 16 patients with 17 chyle leaks (5 chyluria, 8 chylothorax, and 4 chylous ascites) who underwent bipedal lymphangiography (LAG) and postprocedure computed tomography (CT) imaging. Results: In each case, the source of the chyle leak was identified and properlymore » localized to guide further treatment. Of the 16 patients who underwent LAG and postprocedure CT imaging, the initial LAG alone provided the diagnosis and localized the chyle leak in 4 patients (25%); the postprocedure CT imaging provided the diagnosis and localized the chyle leak in 6 patients (37.5%); and the two modalities were equal in the diagnosing and localizing the chyle leak in the remaining 6 patients (37.5%)ConclusionThese cases highlight the unparalleled abilities of LAG and the added benefit of post-LAG CT imaging in the diagnosis and fine anatomic localization of chyle leaks. In addition, these cases demonstrate the retained utility of LAG in these investigations despite the development of alternative tests involving CT, magnetic resonance imaging, and nuclear medicine imaging.« less

Development and verification of methods for predicting flow rates through leaks in valves and couplings

NASA Technical Reports Server (NTRS)

Russell, John M.

1993-01-01

This is the final report of a research effort which addresses the title problem. The report discusses two broad models of flows, which represent the following extreme cases: (1) inertia-dominated flow, where friction is relatively insignificant; and (2) friction-dominated flow where inertia is insignificant. In class (2), the leak channel might consist of the gap between a scratch in a plastic seal and a polished metal plate against which the seal is pressed. Here, the cross section of the leak channel is modeled as a flat bottomed crescent. A publication generated under the present grant period presents an exact solution of the equations of fully-developed laminar pipe flow of a liquid in the case of a crescent beneath a hyperbolic arc. A Master's thesis project supported by the present grant presents the corresponding solution beneath a circular arc. A second publication reviews the flow of a gas through the same channel, which may be analyzed by a standard one-dimensional model (Fanno flow) for an engineering approximation. Finally, the report discusses the design and progress in the fabrication of a leak-test cell, in which one may measure the flow of fluid through a controlled flaw in a seal. The aim of such measurements is to furnish data for comparison with the predictions of the theory.

Modeling the Progression of Epithelial Leak Caused by Overdistension

PubMed Central

Hamlington, Katharine L.; Ma, Baoshun; Smith, Bradford J.; Bates, Jason H. T.

2016-01-01

Mechanical ventilation is necessary for treatment of the acute respiratory distress syndrome but leads to overdistension of the open regions of the lung and produces further damage. Although we know that the excessive stresses and strains disrupt the alveolar epithelium, we know little about the relationship between epithelial strain and epithelial leak. We have developed a computational model of an epithelial monolayer to simulate leak progression due to overdistension and to explain previous experimental findings in mice with ventilator-induced lung injury. We found a nonlinear threshold-type relationship between leak area and increasing stretch force. After the force required to initiate the leak was reached, the leak area increased at a constant rate with further increases in force. Furthermore, this rate was slower than the rate of increase in force, especially at end-expiration. Parameter manipulation changed only the leak-initiating force; leak area growth followed the same trend once this force was surpassed. These results suggest that there is a particular force (analogous to ventilation tidal volume) that must not be exceeded to avoid damage and that changing cell physical properties adjusts this threshold. This is relevant for the development of new ventilator strategies that avoid inducing further injury to the lung. PMID:26951764

A Hydrogen Leak Detection System for Aerospace and Commercial Applications

NASA Technical Reports Server (NTRS)

Hunter, Gary W.; Makel, D. B.; Jansa, E. D.; Patterson, G.; Cova, P. J.; Liu, C. C.; Wu, Q. H.; Powers, W. T.

1995-01-01

Leaks on the space shuttle while on the launch pad have generated interest in hydrogen leak monitoring technology. Microfabricated hydrogen sensors are being fabricated at Case Western Reserve University (CWRU) and tested at NASA Lewis Research Center (LeRC). These sensors have been integrated into hardware and software designed by Aerojet. This complete system allows for multipoint leak monitoring designed to provide leak source and magnitude information in real time. The monitoring system processes data from the hydrogen sensors and presents the operator with a visual indication of the leak location and magnitude. Although the leak monitoring system was designed for hydrogen propulsion systems, the possible applications of this monitoring system are wide ranged. This system is in operation in an automotive application which requires high sensitivity to hydrogen.

Prevention of Postoperative Bile Leak in Partial Cystectomy for Hydatid Liver Disease: Tricks of the Trade.

PubMed

Peker, Kivanc Derya; Gumusoglu, Alpen Yahya; Seyit, Hakan; Kabuli, Hamit Ahmet; Salik, Aysun Erbahceci; Gonenc, Murat; Kapan, Selin; Alis, Halil

2015-12-01

The presence of postoperative bile leak is the major outcome measure for the assessment of operative success in partial cystectomy for hydatid liver disease. However, the optimal operative strategy to reduce the postoperative bile leak rate is yet to be defined. Medical records of patients who underwent partial cystectomy for hydatid liver disease between January 2013 and January 2015 were reviewed in this retrospective analysis. All patients were managed with a specific operative protocol. The primary outcome measure was the rate of persistent postoperative bile leak. The secondary outcome measures were the morbidity and mortality rate, and the length of hospital stay. Twenty-eight patients were included in the study. Only one patient (3.6 %) developed persistent postoperative bile leak. The overall morbidity and mortality rate was 17.8 and 0 %, respectively. The median length of hospital stay was 5 days. Aggressive preventative surgical measures have led to low persistent bile leak rates with low morbidity and mortality.

Thermohydrodynamic analysis of cryogenic liquid turbulent flow fluid film bearings

NASA Technical Reports Server (NTRS)

Andres, Luis San

1993-01-01

A thermohydrodynamic analysis is presented and a computer code developed for prediction of the static and dynamic force response of hydrostatic journal bearings (HJB's), annular seals or damper bearing seals, and fixed arc pad bearings for cryogenic liquid applications. The study includes the most important flow characteristics found in cryogenic fluid film bearings such as flow turbulence, fluid inertia, liquid compressibility and thermal effects. The analysis and computational model devised allow the determination of the flow field in cryogenic fluid film bearings along with the dynamic force coefficients for rotor-bearing stability analysis.

Of Detection Limits and Effective Mitigation: The Use of Infrared Cameras for Methane Leak Detection

NASA Astrophysics Data System (ADS)

Ravikumar, A. P.; Wang, J.; McGuire, M.; Bell, C.; Brandt, A. R.

2017-12-01

Mitigating methane emissions, a short-lived and potent greenhouse gas, is critical to limiting global temperature rise to two degree Celsius as outlined in the Paris Agreement. A major source of anthropogenic methane emissions in the United States is the oil and gas sector. To this effect, state and federal governments have recommended the use of optical gas imaging systems in periodic leak detection and repair (LDAR) surveys to detect for fugitive emissions or leaks. The most commonly used optical gas imaging systems (OGI) are infrared cameras. In this work, we systematically evaluate the limits of infrared (IR) camera based OGI system for use in methane leak detection programs. We analyze the effect of various parameters that influence the minimum detectable leak rates of infrared cameras. Blind leak detection tests were carried out at the Department of Energy's MONITOR natural gas test-facility in Fort Collins, CO. Leak sources included natural gas wellheads, separators, and tanks. With an EPA mandated 60 g/hr leak detection threshold for IR cameras, we test leak rates ranging from 4 g/hr to over 350 g/hr at imaging distances between 5 ft and 70 ft from the leak source. We perform these experiments over the course of a week, encompassing a wide range of wind and weather conditions. Using repeated measurements at a given leak rate and imaging distance, we generate detection probability curves as a function of leak-size for various imaging distances, and measurement conditions. In addition, we estimate the median detection threshold - leak-size at which the probability of detection is 50% - under various scenarios to reduce uncertainty in mitigation effectiveness. Preliminary analysis shows that the median detection threshold varies from 3 g/hr at an imaging distance of 5 ft to over 150 g/hr at 50 ft (ambient temperature: 80 F, winds < 4 m/s). Results from this study can be directly used to improve OGI based LDAR protocols and reduce uncertainty in estimated

Leakage detection on CT myelography for targeted epidural blood patch in spontaneous cerebrospinal fluid leaks: calcified or ossified spinal lesions ventral to the thecal sac.

PubMed

Yoshida, Hiroki; Takai, Keisuke; Taniguchi, Makoto

2014-09-01

The purpose of this study was to describe significant CT myelography findings for determination of the leak site and outcome of targeted epidural blood patch (EBP) in patients with spontaneous CSF leaks. During 2005-2013, spontaneous CSF leaks were diagnosed for 12 patients with orthostatic headaches. The patients received targeted EBP on the basis of CT myelography assessments. Computed tomography myelograms revealed ventral extradural collection of contrast medium distributed over multiple spinal levels (average 16 levels). Intraforaminal contrast medium extravasations were observed at multiple spinal levels (average 8.2 levels). For 8 (67%) of 12 patients, spinal lesions were noted around the thecal sac and included calcified discs with osteophytes, an ossified posterior longitudinal ligament, and an ossified yellow ligament; lesions were mostly located ventral to the thecal sac and were in close contact with the dura mater. The levels of these spinal lesions were considered potential leak sites and were targeted for EBP. For the remaining 4 patients who did not have definite spinal lesions around the thecal sac, leak site determination was based primarily on the contrast gradient hypothesis. The authors hypothesized that the concentration of extradural contrast medium would be the greatest and the same as that of intradural contrast medium at the leak site but that it would decrease with increased distance from the leak site according to the contrast gradient. Epidural blood patch was placed at the level of spinal lesions and/or of the greatest and same concentration of contrast medium between the intradural and extradural spaces. For 10 of the 12 patients, the orthostatic headaches decreased significantly within a week of EBP and disappeared within a month. For the remaining 2 patients, headaches persisted and medical treatment was required for several months. For 3 patients, thick chronic subdural hematomas caused severe headaches and/or disturbed

Intraoperative colonic pulse oximetry in left-sided colorectal surgery: can it predict anastomotic leak?

PubMed

Salusjärvi, Johannes M; Carpelan-Holmström, Monika A; Louhimo, Johanna M; Kruuna, Olli; Scheinin, Tom M

2018-03-01

An anastomotic leak is a fairly common and a potentially lethal complication in colorectal surgery. Objective methods to assess the viability and blood circulation of the anastomosis could help in preventing leaks. Intraoperative pulse oximetry is a cheap, easy to use, fast, and readily available method to assess tissue viability. Our aim was to study whether intraoperative pulse oximetry can predict the development of an anastomotic leak. The study was a prospective single-arm study conducted between the years 2005 and 2011 in Helsinki University Hospital. Patient material consisted of 422 patients undergoing elective left-sided colorectal surgery. The patients were operated by one of the three surgeons. All of the operations were partial or total resections of the left side of the colon with a colorectal anastomosis. The intraoperative colonic oxygen saturation was measured with pulse oximetry from the colonic wall, and the values were analyzed with respect to post-operative complications. 2.3 times more operated anastomotic leaks occurred when the colonic StO 2 was ≤ 90% (11/129 vs 11/293). The mean colonic StO 2 was 91.1 in patients who developed an operated anastomotic leak and 93.0 in patients who did not. With logistic regression analysis, the risk of operated anastomotic leak was 4.2 times higher with StO 2 values ≤ 90%. Low intraoperative colonic StO 2 values are associated with the occurrence of anastomotic leak. Despite its handicaps, the method seems to be useful in assessing anastomotic viability.

Behavior and dynamics of bubble breakup in gas pipeline leaks and accidental subsea oil well blowouts.

PubMed

Wang, Binbin; Socolofsky, Scott A; Lai, Chris C K; Adams, E Eric; Boufadel, Michel C

2018-06-01

Subsea oil well blowouts and pipeline leaks release oil and gas to the environment through vigorous jets. Predicting the breakup of the released fluids in oil droplets and gas bubbles is critical to predict the fate of petroleum compounds in the marine water column. To predict the gas bubble size in oil well blowouts and pipeline leaks, we observed and quantified the flow behavior and breakup process of gas for a wide range of orifice diameters and flow rates. Flow behavior at the orifice transitions from pulsing flow to continuous discharge as the jet crosses the sonic point. Breakup dynamics transition from laminar to turbulent at a critical value of the Weber number. Very strong pure gas jets and most gas/liquid co-flowing jets exhibit atomization breakup. Bubble sizes in the atomization regime scale with the jet-to-plume transition length scale and follow -3/5 power-law scaling for a mixture Weber number. Copyright © 2018 Elsevier Ltd. All rights reserved.

Using a refrigerant leak detector to monitor waste gases from halogenated anesthetics.

PubMed

Rasmussen, Henrik; Thorud, Syvert

2007-09-01

Although halogenated gas anesthetics are indispensable in laboratory animal medicine, they are hazardous when present in the working environment. A simple technique of real-time leak detection and environmental spot monitoring can provide valuable adjunct information to current techniques of time-weighted monitoring. We investigated the minimal limit of detection of halothane, isoflurane, sevoflurane, and desflurane of a leak detector for halogenated gas refrigerants which provides a qualitative response only. We connected a container to an infrared gas analyzer to create a 135-l closed-circuit system and injected liquid halothane, isoflurane, sevoflurane, and desflurane to create calculated gas concentrations of 0.7 to 3.4 parts per million (ppm). The infrared absorbance and response of the leak detector were recorded, and a total of 5 measurements were made per concentration. The actual gas concentrations were calculated by comparison with the agent-specific absorbance standard curve. The leak detector clearly and consistently responded to halothane, isoflurane, sevoflurane, and desflurane from minimal concentrations of 2.1 +/- 0.2, 1.4 +/- 0.04, 0.8 +/- 0.04, and 1.2 +/- 0.4 ppm, respectively, as determined by infrared analysis. Although the detector does not provide numerical and time-weighted results, leak testing of equipment and repeated monitoring of the environment (spot monitoring) can provide valuable real-time information. In addition, with appropriate consideration of the methodological limitations, spot monitoring can be used to predict the likelihood of compliance with time-weighted exposure recommendations. A leak detector therefore represents a simple, effective, and inexpensive instrument for monitoring the leakage of halogenated anesthetic gases from equipment and into the working environment.

Geomechanical analysis to predict the oil leak at the wellbores in Big Hill Strategic Petroleum Reserve

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Byoung Yoon

2014-02-01

Oil leaks were found in wellbores of Caverns 105 and 109 at the Big Hill Strategic Petroleum Reserve site. According to the field observations, two instances of casing damage occurred at the depth of the interbed between the caprock bottom and salt top. A three dimensional finite element model, which contains wellbore element blocks and allows each cavern to be configured individually, is constructed to investigate the wellbore damage mechanism. The model also contains element blocks to represent interface between each lithology and a shear zone to examine the interbed behavior in a realistic manner. The causes of the damagedmore » casing segments are a result of vertical and horizontal movements of the interbed between the caprock and salt dome. The salt top subsides because the volume of caverns below the salt top decrease with time due to salt creep closure, while the caprock subsides at a slower rate because the caprock is thick and stiffer. This discrepancy yields a deformation of the well. The deformed wellbore may fail at some time. An oil leak occurs when the wellbore fails. A possible oil leak date of each well is determined using the equivalent plastic strain failure criterion. A well grading system for a remediation plan is developed based on the predicted leak dates of each wellbore.« less

Transient thermal analysis of fluid systems

NASA Technical Reports Server (NTRS)

Chandler, G. D.; Trust, R. D.

1977-01-01

Computer program performs transient thermal analysis of any 2-node to 200-node-thermal network, which transports heat by fluid flow convection. Program can be modified to add conduction along tubes and radiation.

New technique to prevent prolonged air leak: use of 'Tachosuture' technique.

PubMed

Nishida, Tatsuya; Mikami, Iwao; Fujii, Yoshitaka

2017-02-01

Prolonged air leak (defined as air leak >7 days), caused by pulmonary resection or alveolar-pleural fistula, increases postoperative morbidity, prolongs hospital stay and increases healthcare costs. We describe a new technique ('Tachosuture' technique) to prevent prolonged air leak. The key point of this new technique is that air leak is classified into three types and an absorbable suture is added to a TachoSil ® patch in each type to prevent detachment from the lung parenchyma. Between August 2013 and March 2016, 40 patients underwent thoracoscopic surgery using 'Tachosuture' technique. Postoperative air leak always stopped within 3 days (95% confidence interval for the absence of prolonged air leak: 92.5-100%). It is considered that this simple technique is useful to prevent prolonged air leak.

Assessing Surgeon Behavior Change after Anastomotic Leak in Colorectal Surgery

PubMed Central

Simianu, Vlad V.; Basu, Anirban; Alfonso-Cristancho, Rafael; Thirlby, Richard C.; Flaxman, Abraham D.; Flum, David R.

2016-01-01

Background Recency effect suggests that people disproportionately value events from the immediate past when making decisions, but the extent of this impact on surgeons’ decisions is unknown. This study evaluates for recency effect in surgeons by examining use of preventative leak testing before and after colorectal operations with anastomotic leaks. Materials and Methods Prospective cohort of adult patients (≥18 years) undergoing elective colorectal operations at Washington State hospitals participating in the Surgical Care and Outcomes Assessment Program (2006–2013). The main outcome measure was surgeons’ change in leak testing from 6 months before to 6 months after an anastomotic leak occurred. Results Across 4,854 elective colorectal operations performed by 282 surgeons at 44 hospitals, there was a leak rate of 2.6% (n=124). The 40 leaks (32%) in which the anastomosis was not tested occurred across 25 surgeons. While the ability to detect an overall difference in use of leak testing was limited by small sample size, 9 (36%) of 25 surgeons increased their leak testing by 5 percent points or more after leaks in cases where the anastomosis was not tested. Surgeons who increased their leak testing more frequently performed operations for diverticulitis (45% vs 33%), more frequently began their cases laparoscopically (65% vs 37%), and had longer mean operative times (195±99 vs 148±87 minutes), all p<0.001. Conclusions Recency effect was demonstrated by only one-third of eligible surgeons. Understanding the extent to which clinical decisions may be influenced by recency effect may be important in crafting quality improvement initiatives that require clinician behavior change. PMID:27664886

Assessing surgeon behavior change after anastomotic leak in colorectal surgery.

PubMed

Simianu, Vlad V; Basu, Anirban; Alfonso-Cristancho, Rafael; Thirlby, Richard C; Flaxman, Abraham D; Flum, David R

2016-10-01

Recency effect suggests that people disproportionately value events from the immediate past when making decisions, but the extent of this impact on surgeons' decisions is unknown. This study evaluates for recency effect in surgeons by examining use of preventative leak testing before and after colorectal operations with anastomotic leaks. Prospective cohort of adult patients (≥18 y) undergoing elective colorectal operations at Washington State hospitals participating in the Surgical Care and Outcomes Assessment Program (2006-2013). The main outcome measure was surgeons' change in leak testing from 6 mo before to 6 mo after an anastomotic leak occurred. Across 4854 elective colorectal operations performed by 282 surgeons at 44 hospitals, there was a leak rate of 2.6% (n = 124). The 40 leaks (32%) in which the anastomosis was not tested occurred across 25 surgeons. While the ability to detect an overall difference in use of leak testing was limited by small sample size, nine (36%) of 25 surgeons increased their leak testing by 5% points or more after leaks in cases where the anastomosis was not tested. Surgeons who increased their leak testing more frequently performed operations for diverticulitis (45% versus 33%), more frequently began their cases laparoscopically (65% versus 37%), and had longer mean operative times (195 ± 99 versus 148 ± 87 min), all P < 0.001. Recency effect was demonstrated by only one-third of eligible surgeons. Understanding the extent to which clinical decisions may be influenced by recency effect may be important in crafting quality improvement initiatives that require clinician behavior change. Copyright © 2016 Elsevier Inc. All rights reserved.

Update on pancreatic cyst fluid analysis

PubMed Central

Rockacy, Matthew; Khalid, Asif

2013-01-01

Pancreatic cystic lesions (PCL) may be incidentally detected in up to 13.5% of patients. These represent a wide variety of lesions including mucinous cysts [intraductal papillary mucinous neoplasms (IPMN) and mucinous cystic neoplasms (MCN)] that have malignant potential. The difficulty in identifying the various PCL and their unpredictable potential for malignant degeneration makes their management cumbersome. The current diagnostic evaluation of PCL often includes EUS-guided fine needle aspiration (EUS-FNA) for cyst fluid analysis. Cyst fluid can be analyzed for tumor markers, cytology, mucins, DNA analysis and amylase. Pancreatic cyst CEA level is considered the most accurate tumor marker for diagnosing mucinous cysts. Approximately 0.2 to 1.0 mL of cyst fluid is required to run the test and a cut-off of 192 ng/ mL can be expected to capture ~75% of mucinous cysts. The presence of a KRAS mutation is very specific for a mucinous cyst but lacks sensitivity. Cytology is especially helpful in diagnosing malignancy typically in the presence of a solid component in the cyst. Newer markers to improve diagnostic accuracy are on the horizon, but clinical studies are awaited. PMID:24714589

Clinical Factors and Postoperative Impact of Bile Leak After Liver Resection.

PubMed

Martin, Allison N; Narayanan, Sowmya; Turrentine, Florence E; Bauer, Todd W; Adams, Reid B; Stukenborg, George J; Zaydfudim, Victor M

2018-04-01

Despite technical advances, bile leak remains a significant complication after hepatectomy. The current study uses a targeted multi-institutional dataset to characterize perioperative factors that are associated with bile leakage after hepatectomy to better understand the impact of bile leak on morbidity and mortality. Adult patients in the 2014-2015 ACS NSQIP targeted hepatectomy dataset were linked to the ACS NSQIP PUF dataset. Bivariable and multivariable regression analyses were used to assess the associations between clinical factors and post-hepatectomy bile leak. Of 6859 patients, 530 (7.7%) had a postoperative bile leak. Proportion of bile leaks was significantly greater in patients after major compared to minor hepatectomy (12.6 vs. 5.1%, p < 0.001). The proportion of patients with bile leak was significantly greater in patients after major hepatectomy who had concomitant enterohepatic reconstruction (31.8 vs. 10.1%, p < 0.001). Postoperative mortality was significantly greater in patients with bile leaks (6.0 vs. 1.7%, p < 0.001). After adjusting for significant covariates, bile leak was independently associated with increased risk of postoperative morbidity (OR = 4.55; 95% CI 3.72-5.56; p < 0.001). After adjusting for significant effects of postoperative complications, liver failure, and reoperation (all p<0.001), bile leak was not independently associated with increased risk of postoperative mortality (p = 0.262). Major hepatectomy and enterohepatic biliary reconstruction are associated with significantly greater rates of bile leak after liver resection. Bile leak is independently associated with significant postoperative morbidity. Mitigation of bile leak is critical in reducing morbidity and mortality after liver resection.

Fighting the Epidemic of Nuclear Plant Leaks.

ERIC Educational Resources Information Center

Udell, Richard A.

1983-01-01

The current epidemic of steam generator tube leaks alone should put to rest the rosy future once envisioned for nuclear power. It is impossible to regulate quality into a nuclear plant; it must be built and designed that way. The economic impact of the leaks is discussed. (RM)

Chemseal 3808-A2 penetration into small leak path

NASA Technical Reports Server (NTRS)

Carruth, M. R., Jr.; Dehaye, R. F.

1988-01-01

A possible fix to a leak in the oxidizer system of the Space Shuttle Discovery's attitude control system was proposed by MSFC. This fix involved the passing of a shuttlecock past the leaking Dynaflow fitting and sealing the vent tube containing the fitting with Chemseal 3808-A2. The question of whether the Chemseal 3808-A2 can flow into the leak path and provide a better seal was addressed analytically and by experiment to verify the analytical formula used. The results show that the equations are applicable and that the Chemseal will flow into the expected leak path and seal.

Prognostic Factors and Significance of Gastrointestinal Leak After Cytoreductive Surgery (CRS) with Heated Intraperitoneal Chemotherapy (HIPEC).

PubMed

Chouliaras, Konstantinos; Levine, Edward A; Fino, Nora; Shen, Perry; Votanopoulos, Konstantinos I

2017-04-01

Gastrointestinal leak (GIL) after cytoreductive surgery with heated intraperitoneal chemotherapy (CRS/HIPEC) is associated with significant morbidity and mortality. This study aimed to identify GIL prognostic factors and its impact on overall survival. A retrospective analysis of a prospectively maintained database comprising 1270 CRS/HIPEC procedures was performed. Type of GIL, functional and resection status, morbidity, mortality, and survival were reviewed. Gastrointestinal leaks were identified in 8.7% (110/1270) of CRS/HIPEC procedures, including 53 anastomotic leaks (4.2%), 53 hollow viscus perforations (4.2%), and four leaks at unknown sites. The multivariate predictors of leak were Eastern Cooperative Oncology Group (ECOG) functional status (ECOG 1 vs. 0: odds ratio [OR] 2.12, p = 0.009; ECOG 2 vs. 0: OR 2.90, p = 0.004), and number of anastomoses (OR 5.34; p < 0.0001). The in-hospital mortality rate for the GIL cohort was 21.8% (24/110), with a 72% (80/110) reoperation rate. The leak cohort had a higher major morbidity rate (88.3 vs. 23.3%; p < 0.0001), a longer hospital stay (39.0 vs. 9.9 days; p < 0.0001), and a longer intensive care unit (ICU) stay (7.7 vs. 1.7 days; p = 0.0003). After surgical mortality was excluded, the overall survival periods for the leak and no-leak patients with complete cytoreduction were respectively 1.5 and 4.98 years (p = 0.0001). Clinically significant decreases in survival were observed for all primary malignancies. Gastrointestinal leak after CRS/HIPEC is a source of significant mortality, with a decrease in overall survival even after complete CRS. Preoperative functional status and number of anastomoses are predictors of leak for CRS/HIPEC patients.

Influence of preoperative radiation field on postoperative leak rates in esophageal cancer patients after trimodality therapy.

PubMed

Juloori, Aditya; Tucker, Susan L; Komaki, Ritsuko; Liao, Zhongxing; Correa, Arlene M; Swisher, Stephen G; Hofstetter, Wayne L; Lin, Steven H

2014-04-01

Postoperative morbidities, such as anastomotic leaks, are common after trimodality therapy (chemoradiation followed by surgery) for esophageal cancer. We investigated for factors associated with an increased incidence of anastomotic leaks. Data from 285 esophageal cancer patients treated from 2000 to 2011 with trimodality therapy were analyzed. Anastomotic location relative to preoperative radiation field was assessed using postoperative computed tomographic imaging. Logistic regression was used to evaluate for factors associated with any or clinically relevant (CR) (≥ grade 2) leaks. Overall anastomotic leak rate was 11% (31 of 285), and CR leak rate was 6% (17 of 285). Multivariable analysis identified body mass index (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.00-1.17; OR, 1.11, 95% CI, 1.01-1.22), three-field surgery (OR, 10.01; 95% CI, 3.83-26.21; OR, 4.83; 95% CI, 1.39-16.71), and within radiation field ("in-field") anastomosis (OR, 5.37; 95% CI, 2.21-13.04; OR, 8.63; 95% CI, 2.90-25.65) as independent predictors of both all grade and CR leaks, respectively. While patients with distal esophageal tumors and Ivor-Lewis surgery had the lowest incidence of all grade (6.5%) and CR leaks (4.2%), most of the leaks were associated with the anastomosis constructed within the field of radiation (in-field: 39% and 30% versus out-of-field: 2.6% and 1.0%, respectively, for total and CR leaks, p less than 0.0001, Fisher's exact test). Esophagogastric anastomosis placed within the preoperative radiation field was a very strong predictor for anastomotic leaks in esophageal cancer patients treated with trimodality therapy, among other factors. Surgical planning should include a critical evaluation of the preoperative radiation fields to ensure proper anastomotic placement after chemoradiation therapy.

Resilience to leaking--dynamic systems modeling of information security.

PubMed

Hamacher, Kay

2012-01-01

Leaking of confidential material is a major threat to information security within organizations and to society as a whole. This insight has gained traction in the political realm since the activities of Wikileaks, which hopes to attack 'unjust' systems or 'conspiracies'. Eventually, such threats to information security rely on a biologistic argument on the benefits and drawbacks that uncontrolled leaking might pose for 'just' and 'unjust' entities. Such biological metaphors are almost exclusively based on the economic advantage of participants. Here, I introduce a mathematical model of the complex dynamics implied by leaking. The complex interactions of adversaries are modeled by coupled logistic equations including network effects of econo-communication networks. The modeling shows, that there might arise situations where the leaking envisioned and encouraged by Wikileaks and the like can strengthen the defending entity (the 'conspiracy'). In particular, the only severe impact leaking can have on an organization seems to originate in the exploitation of leaks by another entity the organization competes with. Therefore, the model suggests that leaks can be used as a `tactical mean' in direct adversary relations, but do not necessarily increase public benefit and societal immunization to 'conspiracies'. Furthermore, within the model the exploitation of the (open) competition between entities seems to be a more promising approach to control malicious organizations : divide-et-impera policies triumph here.

Autogenous Metallic Pipe Leak Repair in Potable Water Systems.

PubMed

Tang, Min; Triantafyllidou, Simoni; Edwards, Marc A

2015-07-21

Copper and iron pipes have a remarkable capability for autogenous repair (self-repair) of leaks in potable water systems. Field studies revealed exemplars that metallic pipe leaks caused by nails, rocks, and erosion corrosion autogenously repaired, as confirmed in the laboratory experiments. This work demonstrated that 100% (N = 26) of 150 μm leaks contacting representative bulk potable water in copper pipes sealed autogenously via formation of corrosion precipitates at 20-40 psi, pH 3.0-11.0, and with upward and downward leak orientations. Similar leaks in carbon steel pipes at 20 psi self-repaired at pH 5.5 and 8.5, but two leaks did not self-repair permanently at pH 11.0 suggesting that water chemistry may control the durability of materials that seal the leaks and therefore the permanence of repair. Larger 400 μm holes in copper pipes had much lower (0-33%) success of self-repair at pH 3.0-11.0, whereas all 400 μm holes in carbon steel pipes at 20 psi self-repaired at pH 4.0-11.0. Pressure tests indicated that some of the repairs created at 20-40 psi ambient pressure could withstand more than 100 psi without failure. Autogenous repair has implications for understanding patterns of pipe failures, extending the lifetime of decaying infrastructure, and developing new plumbing materials.

Overview of MSFC's Applied Fluid Dynamics Analysis Group Activities

NASA Technical Reports Server (NTRS)

Garcia, Roberto; Griffin, Lisa; Williams, Robert

2003-01-01

TD64, the Applied Fluid Dynamics Analysis Group, is one of several groups with high-fidelity fluids design and analysis expertise in the Space Transportation Directorate at Marshall Space Flight Center (MSFC). TD64 assists personnel working on other programs. The group participates in projects in the following areas: turbomachinery activities, nozzle activities, combustion devices, and the Columbia accident investigation.

Fugitive methane emissions from leak-prone natural gas distribution infrastructure in urban environments.

PubMed

Hendrick, Margaret F; Ackley, Robert; Sanaie-Movahed, Bahare; Tang, Xiaojing; Phillips, Nathan G

2016-06-01

Fugitive emissions from natural gas systems are the largest anthropogenic source of the greenhouse gas methane (CH4) in the U.S. and contribute to the risk of explosions in urban environments. Here, we report on a survey of CH4 emissions from 100 natural gas leaks in cast iron distribution mains in Metro Boston, MA. Direct measures of CH4 flux from individual leaks ranged from 4.0 - 2.3 × 10(4) g CH4•day(-1). The distribution of leak size is positively skewed, with 7% of leaks contributing 50% of total CH4 emissions measured. We identify parallels in the skewed distribution of leak size found in downstream systems with midstream and upstream stages of the gas process chain. Fixing 'superemitter' leaks will disproportionately stem greenhouse gas emissions. Fifteen percent of leaks surveyed qualified as potentially explosive (Grade 1), and we found no difference in CH4 flux between Grade 1 leaks and all remaining leaks surveyed (p = 0.24). All leaks must be addressed, as even small leaks cannot be disregarded as 'safely leaking.' Key methodological impediments to quantifying and addressing the impacts of leaking natural gas distribution infrastructure involve inconsistencies in the manner in which gas leaks are defined, detected, and classified. To address this need, we propose a two-part leak classification system that reflects both the safety and climatic impacts of natural gas leaks. Copyright © 2016 Elsevier Ltd. All rights reserved.

Financial validation of the European Society of Thoracic Surgeons risk score predicting prolonged air leak after video-assisted thoracic surgery lobectomy.

PubMed

Brunelli, Alessandro; Pompili, Cecilia; Dinesh, Padma; Bassi, Vinod; Imperatori, Andrea

2018-04-27

The objective of this study was to verify whether the European Society of Thoracic Surgeons prolonged air leak risk score for video-assisted thoracoscopic lobectomy was associated with incremental postoperative costs. We retrospectively analyzed 353 patients subjected to video-assisted thoracoscopic lobectomy or segmentectomy (April 2014 to March 2016). Postoperative costs were obtained from the hospital Finance Department. Patients were grouped in different classes of risk according to their prolonged air leak risk score. To verify the independent association of the prolonged air leak risk score with postoperative costs, we performed a stepwise multivariable regression analysis in which the dependent variable was postoperative cost. Prolonged air leak developed in 56 patients (15.9%). Their length of stay was 3 days longer compared with those without prolonged air leak (8.3 vs 5.4, P < .0001). Their postoperative cost was higher than that of patients without prolonged air leak: $5939.8 versus $4381.7 (P = .001). After grouping the patients according to their prolonged air leak risk score, prolonged air leak incidence was 12.3% in class A, 13.7% in class B, 28.8% in class C, and 22.2% in class D (P = .020). The average postoperative cost was $4031.0 in class A, $4498.2 in class B, $6146.6 in class C, and $6809.3 in class D (analysis of variance test, P < .001). Multivariable regression analysis showed that being in classes C and D of PAL score (P = .001) and the presence of cardiopulmonary complications (P < .0001) were the only independent factors significantly associated with postoperative costs. We financially validated the European Society of Thoracic Surgeons prolonged air leak risk score for video-assisted thoracoscopic lobectomies, which appears useful in selecting those patients in whom the application of additional intraoperative interventions to avoid prolonged air leak may be more cost-effective. Copyright © 2018 The American Association

Schlieren optics for leak detection

NASA Technical Reports Server (NTRS)

Peale, Robert E.; Ruffin, Alranzo B.

1995-01-01

The purpose of this research was to develop an optical method of leak detection. Various modifications of schlieren optics were explored with initial emphasis on leak detection of the plumbing within the orbital maneuvering system of the space shuttle (OMS pod). The schlieren scheme envisioned for OMS pod leak detection was that of a high contrast pattern on flexible reflecting material imaged onto a negative of the same pattern. We find that the OMS pod geometry constrains the characteristic length scale of the pattern to the order of 0.001 inch. Our experiments suggest that optical modulation transfer efficiency will be very low for such patterns, which will limit the sensitivity of the technique. Optical elements which allow a negative of the scene to be reversibly recorded using light from the scene itself were explored for their potential in adaptive single-ended schlieren systems. Elements studied include photochromic glass, bacteriorhodopsin, and a transmissive liquid crystal display. The dynamics of writing and reading patterns were studied using intensity profiles from recorded images. Schlieren detection of index gradients in air was demonstrated.

Measurement of Submerged Oil/Gas Leaks using ROV Video

NASA Astrophysics Data System (ADS)

Shaffer, Franklin; de Vera, Giorgio; Lee, Kenneth; Savas, Ömer

2013-11-01

Drilling for oil or gas in the Gulf of Mexico is increasing rapidly at depths up to three miles. The National Commission on the Deepwater Horizon Oil Leak concluded that inaccurate estimates of the leak rate from the Deepwater Horizon caused an inadequate response and attempts to cap the leak to fail. The first response to a submerged oil/gas leak will be to send a Remotely Operated Vehicle (ROV) down to view the leak. During the response to the Deepwater Horizon crisis, the authors Savas and Shaffer were members of the Flow Rate Technical Group's Plume Team who used ROV video to develop the FRTG's first official estimates of the oil leak rate. Savas and Shaffer developed an approach using the larger, faster jet features (e.g., turbulent eddies, vortices, entrained particles) in the near-field developing zone to measure discharge rates. The authors have since used the Berkeley Tow Tank to test this approach on submerged dye-colored water jets and compressed air jets. Image Correlation Velocimetry has been applied to measure the velocity of visible features. Results from tests in the Berkeley Tow Tank and submerged oil jets in the OHMSETT facility will be presented.

Local Leak Detection and Health Monitoring of Pressurized Tanks

NASA Technical Reports Server (NTRS)

Polzin, Kurt; Witherow, William; Korman, Valentin; Sinko, John; Hendrickson, Adam

2011-01-01

An optical gas-detection sensor safely monitors pressurized systems (such as cryogenic tanks) and distribution systems for leaks. This sensor system is a fiber-coupled, solid optical body interferometer that allows for the miniaturized sensing element of the device to be placed in the smallest of recesses, and measures a wide range of gas species and densities (leaks). The deflection of the fringe pattern is detected and recorded to yield the time-varying gas density in the gap. This technology can be used by manufacturers or storage facilities with toxic, hazardous, or explosive gases. The approach is to monitor the change in the index of refraction associated with low-level gas leaks into a vacuum environment. The completion of this work will provide NASA with an enabling capability to detect gas system leaks in space, and to verify that pressurized systems are in a safe (i.e. non-leaking) condition during manned docking and transit operations. By recording the output of the sensor, a time-history of the leak can be constructed to indicate its severity. Project risk is mitigated by having several interferometric geometries and detection techniques available, each potentially leveraging hardware and lessons learned to enhance detectability.

Detection of Leaks in Water Distribution System using Non-Destructive Techniques

NASA Astrophysics Data System (ADS)

Aslam, H.; Kaur, M.; Sasi, S.; Mortula, Md M.; Yehia, S.; Ali, T.

2018-05-01

Water is scarce and needs to be conserved. A considerable amount of water which flows in the water distribution systems was found to be lost due to pipe leaks. Consequently, innovations in methods of pipe leakage detections for early recognition and repair of these leaks is vital to ensure minimum wastage of water in distribution systems. A major component of detection of pipe leaks is the ability to accurately locate the leak location in pipes through minimum invasion. Therefore, this paper studies the leak detection abilities of the three NDT’s: Ground Penetration Radar (GPR) and spectrometer and aims at determining whether these instruments are effective in identifying the leak. An experimental setup was constructed to simulate the underground conditions of water distribution systems. After analysing the experimental data, it was concluded that both the GPR and the spectrometer were effective in detecting leaks in the pipes. However, the results obtained from the spectrometer were not very differentiating in terms of observing the leaks in comparison to the results obtained from the GPR. In addition to this, it was concluded that both instruments could not be used if the water from the leaks had reached on the surface, resulting in surface ponding.

Endoscopic dilation for treatment of anastomotic leaks following transhiatal esophagectomy.

PubMed

Bhasin, D K; Sharma, B C; Gupta, N M; Sinha, S K; Singh, K

2000-06-01

Anastomotic leak is a known complication after transhiatal esophagectomy (THE) and cervical esophagogastric anastomosis. Conservative management takes a long time to heal such leaks. We assessed the role of endoscopic dilation in patients with anastomotic leak following THE. Eight consecutive patients (seven men, one woman; mean age 51) with anastomotic leak following THE were subjected to endoscopic dilation using Savary Gilliard dilators of 7-15 mm diameter. The mean interval between surgery and detection of leak was 9 days (range 5-22 days) and dilation was performed at a mean interval of 11.4 days (range 1-20 days) after detection of the leak. Drainage from fistulas stopped completely after 1-8 days (mean 3 days). X-ray with water soluble contrast showed closure of the fistula in all cases. Duration of follow-up ranged from 2 to 12 months. Anastomotic strictures developed in three patients. These patients required three sessions each of repeat dilation, and were alive at follow-up periods of 2, 4, and 12 months, respectively. One patient developed recurrence of growth at an anastomotic site. Four patients died because of distant metastasis. Bougie dilation of anastomotic sites is a safe and effective technique for the healing of anastomotic leaks following THE. However there is a need for a prospective randomized trial comparing endoscopic dilation with no dilation in patients with anastomotic leaks following THE.

Refrigerant leak detector

NASA Technical Reports Server (NTRS)

Byrne, E. J.

1979-01-01

Quantitative leak detector visually demonstrates refrigerant loss from precision volume of large refrigeration system over established period of time from single test point. Mechanical unit is less costly than electronic "sniffers" and is more reliable due to absence of electronic circuits that are susceptible to drift.

40 CFR 63.1255 - Standards: Equipment leaks.

Code of Federal Regulations, 2013 CFR

2013-07-01

... requirements of this section. (9) Equipment that is in organic HAP service, but is in such service less than... required in paragraph (g)(9) of this section. (10) When each leak is detected by visual, audible, or... paragraphs (c)(5) through (9) of this section. (ii) Leak definition. The instrument reading, as determined by...

Gas Leak Detection by Dilution of Atmospheric Oxygen

PubMed Central

Lambrecht, Armin; Maier, Eric; Strahl, Thomas; Herbst, Johannes

2017-01-01

Gas leak detection is an important issue in infrastructure monitoring and industrial production. In this context, infrared (IR) absorption spectroscopy is a major measurement method. It can be applied in an extractive or remote detection scheme. Tunable laser spectroscopy (TLS) instruments are able to detect CH4 leaks with column densities below 10 ppm·m from a distance of 30 m in less than a second. However, leak detection of non-IR absorbing gases such as N2 is not possible in this manner. Due to the fact that any leaking gas displaces or dilutes the surrounding background gas, an indirect detection is still possible. It is shown by sensitive TLS measurements of the ambient background concentration of O2 that N2 leaks can be localized with extractive and standoff methods for distances below 1 m. Minimum leak rates of 0.1 mbar·L/s were determined. Flow simulations confirm that the leakage gas typically effuses in a narrow jet. The sensitivity is mainly determined by ambient flow conditions. Compared to TLS detection of CH4 at 1651 nm, the indirect method using O2 at 761 nm is experimentally found to be less sensitive by a factor of 100. However, the well-established TLS of O2 may become a universal tool for rapid leakage screening of vessels that contain unknown or inexpensive gases, such as N2. PMID:29206133

The diagnostic performance of leak-plugging automated segmentation versus manual tracing of breast lesions on ultrasound images.

PubMed

Xiong, Hui; Sultan, Laith R; Cary, Theodore W; Schultz, Susan M; Bouzghar, Ghizlane; Sehgal, Chandra M

2017-05-01

To assess the diagnostic performance of a leak-plugging segmentation method that we have developed for delineating breast masses on ultrasound images. Fifty-two biopsy-proven breast lesion images were analyzed by three observers using the leak-plugging and manual segmentation methods. From each segmentation method, grayscale and morphological features were extracted and classified as malignant or benign by logistic regression analysis. The performance of leak-plugging and manual segmentations was compared by: size of the lesion, overlap area ( O a ) between the margins, and area under the ROC curves ( A z ). The lesion size from leak-plugging segmentation correlated closely with that from manual tracing ( R 2 of 0.91). O a was higher for leak plugging, 0.92 ± 0.01 and 0.86 ± 0.06 for benign and malignant masses, respectively, compared to 0.80 ± 0.04 and 0.73 ± 0.02 for manual tracings. Overall O a between leak-plugging and manual segmentations was 0.79 ± 0.14 for benign and 0.73 ± 0.14 for malignant lesions. A z for leak plugging was consistently higher (0.910 ± 0.003) compared to 0.888 ± 0.012 for manual tracings. The coefficient of variation of A z between three observers was 0.29% for leak plugging compared to 1.3% for manual tracings. The diagnostic performance, size measurements, and observer variability for automated leak-plugging segmentations were either comparable to or better than those of manual tracings.

Leak detectability of the Norman Wells pipeline by mass balance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liou, J.C.P.

Pipeline leak detection using software-based systems is becoming common practice. The detectability of such systems is measured by how small and how quickly a leak can be detected. Algorithms used and measurement uncertainties determine leak detectability. This paper addresses leak detectability using mass balance, establishes leak detectability for Norman Wells pipelines, and compares it with field leak test results. The pipeline is operated by the Interprovincial Pipe Line (IPL) Inc., of Edmonton, Canada. It is a 12.75-inch outside diameter steel pipe with variable wall thickness. The length of the pipe is approximately 550 miles (868.9 km). The pipeline transports lightmore » crude oil at a constant flow rate of about 250 m{sup 3}/hr. The crude oil can enter the pipeline at two locations. Besides the Norman Wells inlet, there is a side line near Zama terminal that can inject crude oil into the pipeline.« less

Hollow-core fiber sensing technique for pipeline leak detection

NASA Astrophysics Data System (ADS)

Challener, W. A.; Kasten, Matthias A.; Karp, Jason; Choudhury, Niloy

2018-02-01

Recently there has been increased interest on the part of federal and state regulators to detect and quantify emissions of methane, an important greenhouse gas, from various parts of the oil and gas infrastructure including well pads and pipelines. Pressure and/or flow anomalies are typically used to detect leaks along natural gas pipelines, but are generally very insensitive and subject to false alarms. We have developed a system to detect and localize methane leaks along gas pipelines that is an order of magnitude more sensitive by combining tunable diode laser spectroscopy (TDLAS) with conventional sensor tube technology. This technique can potentially localize leaks along pipelines up to 100 km lengths with an accuracy of +/-50 m or less. A sensor tube buried along the pipeline with a gas-permeable membrane collects leaking gas during a soak period. The leak plume within the tube is then carried to the nearest sensor node along the tube in a purge cycle. The time-to-detection is used to determine leak location. Multiple sensor nodes are situated along the pipeline to minimize the time to detection, and each node is composed of a short segment of hollow core fiber (HCF) into which leaking gas is transported quickly through a small pressure differential. The HCF sensing node is spliced to standard telecom solid core fiber which transports the laser light for spectroscopy to a remote interrogator. The interrogator is multiplexed across the sensor nodes to minimize equipment cost and complexity.

ISS-CREAM Thermal and Fluid System Design and Analysis

NASA Technical Reports Server (NTRS)

Thorpe, Rosemary S.

2015-01-01

Thermal and Fluids Analysis Workshop (TFAWS), Silver Spring MD NCTS 21070-15. The ISS-CREAM (Cosmic Ray Energetics And Mass for the International Space Station) payload is being developed by an international team and will provide significant cosmic ray characterization over a long time frame. Cold fluid provided by the ISS Exposed Facility (EF) is the primary means of cooling for 5 science instruments and over 7 electronics boxes. Thermal fluid integrated design and analysis was performed for CREAM using a Thermal Desktop model. This presentation will provide some specific design and modeling examples from the fluid cooling system, complex SCD (Silicon Charge Detector) and calorimeter hardware, and integrated payload and ISS level modeling. Features of Thermal Desktop such as CAD simplification, meshing of complex hardware, External References (Xrefs), and FloCAD modeling will be discussed.

An improved PCA method with application to boiler leak detection.

PubMed

Sun, Xi; Marquez, Horacio J; Chen, Tongwen; Riaz, Muhammad

2005-07-01

Principal component analysis (PCA) is a popular fault detection technique. It has been widely used in process industries, especially in the chemical industry. In industrial applications, achieving a sensitive system capable of detecting incipient faults, which maintains the false alarm rate to a minimum, is a crucial issue. Although a lot of research has been focused on these issues for PCA-based fault detection and diagnosis methods, sensitivity of the fault detection scheme versus false alarm rate continues to be an important issue. In this paper, an improved PCA method is proposed to address this problem. In this method, a new data preprocessing scheme and a new fault detection scheme designed for Hotelling's T2 as well as the squared prediction error are developed. A dynamic PCA model is also developed for boiler leak detection. This new method is applied to boiler water/steam leak detection with real data from Syncrude Canada's utility plant in Fort McMurray, Canada. Our results demonstrate that the proposed method can effectively reduce false alarm rate, provide effective and correct leak alarms, and give early warning to operators.

Assessing copper pinhole leaks in residential plumbing.

PubMed

Edwards, M; Rushing, J C; Kvech, S; Reiber, S

2004-01-01

Pinhole leaks in copper tubes are a major problem for homeowners, and an aggressive conscientious effort by utilities is recommended to diagnose the problem and identify potential solutions. In a case study at one utility, pinhole leak frequency data was compiled and a methodology was followed that might prove to be a useful guide for those facing similar problems.

40 CFR 53.52 - Leak check test.

Code of Federal Regulations, 2013 CFR

2013-07-01

... be verified at the highest and lowest pressures and temperatures used in the tests and shall be... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Leak check test. 53.52 Section 53.52... Leak check test. (a) Overview. In section 7.4.6 of 40 CFR part 50, appendix L, the sampler is required...

Appropriate fluid regimens to prevent bronchopulmonary dysplasia.

PubMed

Tammela, O K

1995-01-01

Pulmonary oedema is an important problem in premature neonates with surfactant deficiency because of fluid accumulation in the lung interstitium and reduced urine output. Some retrospective reports suggest that excessive early hydration might increase the risk of bronchopulmonary dysplasia (BPD). Only three prospective studies evaluating low or conventional fluid administration regimens to very low birth weight infants have been published. According to their results no significant differences in the incidence of BPD have been shown. However, fluid restriction seems to improve the outcome of the infants because of decreased incidence of haemodynamically significant patent ductus arteriosus, necrotizing enterocolitis, pulmonary air leaks and decreased mortality. The appropriate amount of sodium in the intravenous fluids during the first days of life needs further evaluation. In tiny infants with birth weights from 500 to 800g intensive monitoring of fluid balance is essential to control the extremely high fluid losses due to evaporation. Undernutrition is a risk factor of BPD and therefore it is important to start parenteral nutrition early. The benefit of the use of colloids as volume expanders is controversial. According to some retrospective reports there might be an association with increased use of colloidal fluids during the first days of life and the development of BPD. Early excessive fluid administration might constitute a potential risk for low birth weight infants with hyaline membrane disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Glutaredoxin-2 is required to control proton leak through uncoupling protein-3.

PubMed

Mailloux, Ryan J; Xuan, Jian Ying; Beauchamp, Brittany; Jui, Linda; Lou, Marjorie; Harper, Mary-Ellen

2013-03-22

Glutathionylation has emerged as a key modification required for controlling protein function in response to changes in cell redox status. Recently, we showed that the glutathionylation state of uncoupling protein-3 (UCP3) modulates the leak of protons back into the mitochondrial matrix, thus controlling reactive oxygen species production. However, whether or not UCP3 glutathionylation is mediated enzymatically has remained unknown because previous work relied on the use of pharmacological agents, such as diamide, to alter the UCP3 glutathionylation state. Here, we demonstrate that glutaredoxin-2 (Grx2), a matrix oxidoreductase, is required to glutathionylate and inhibit UCP3. Analysis of bioenergetics in skeletal muscle mitochondria revealed that knock-out of Grx2 (Grx2(-/-)) increased proton leak in a UCP3-dependent manner. These effects were reversed using diamide, a glutathionylation catalyst. Importantly, the increased leak did not compromise coupled respiration. Knockdown of Grx2 augmented proton leak-dependent respiration in primary myotubes from wild type mice, an effect that was absent in UCP3(-/-) cells. These results confirm that Grx2 deactivates UCP3 by glutathionylation. To our knowledge, this is the first enzyme identified to regulate UCP3 by glutathionylation and is the first study on the role of Grx2 in the regulation of energy metabolism.

Methods and apparatus for measuring small leaks from carbon dioxide sequestration facilities

DOEpatents

Nelson, Jr., David D.; Herndon, Scott C.

2018-01-02

In one embodiment, a CO.sub.2 leak detection instrument detects leaks from a site (e.g., a CO.sub.2 sequestration facility) using rapid concentration measurements of CO.sub.2, O.sub.2 and optionally water concentration that are achieved, for example, using laser spectroscopy (e.g. direct absorption laser spectroscopy). Water vapor in the sample gas may not be removed, or only partially removed. The sample gas may be collected using a multiplexed inlet assembly from a plurality of locations. CO.sub.2 and O.sub.2 concentrations may be corrected based on the water concentration. A resulting dataset of the CO.sub.2 and O.sub.2 concentrations is analyzed over time intervals to detect any changes in CO.sub.2 concentration that are not anti-correlated with O.sub.2 concentration, and to identify a potential CO.sub.2 leak in response thereto. The analysis may include determining eddy covariance flux measurements of sub-surface potential carbon.

Improved techniques reduce face mask leak during simulated neonatal resuscitation: study 2.

PubMed

Wood, Fiona E; Morley, Colin J; Dawson, Jennifer A; Kamlin, C Omar F; Owen, Louise S; Donath, Susan; Davis, Peter G

2008-05-01

Techniques of positioning and holding neonatal face masks vary. Studies have shown that leak at the face mask is common and often substantial irrespective of operator experience. (1) To identify a technique for face mask placement and hold which will minimise mask leak. (2) To investigate the effect of written instruction and demonstration of the identified technique on mask leak for two round face masks. Three experienced neonatologists compared methods of placing and holding face masks to minimise the leak for Fisher & Paykel 60 mm and Laerdal size 0/1 masks. 50 clinical staff gave positive pressure ventilation to a modified manikin designed to measure leak at the face mask. They were provided with written instructions on how to position and hold each mask and then received a demonstration. Face mask leak was measured after each teaching intervention. A technique of positioning and holding the face masks was identified which minimised leak. The mean (SD) mask leaks before instruction, after instruction and after demonstration were 55% (31), 49% (30), 33% (26) for the Laerdal mask and 57% (25), 47% (28), 32% (30) for the Fisher & Paykel mask. There was no significant difference in mask leak between the two masks. Written instruction alone reduced leak by 8.8% (CI 1.4% to 16.2%) for either mask; when combined with a demonstration mask leak was reduced by 24.1% (CI 16.4% to 31.8%). Written instruction and demonstration of the identified optimal technique resulted in significantly reduced face mask leak.

Influence of wetting effect at the outer surface of the pipe on increase in leak rate - experimental results and discussion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Isozaki, Toshikuni; Shibata, Katsuyuki

1997-04-01

Experimental and computed results applicable to Leak Before Break analysis are presented. The specific area of investigation is the effect of the temperature distribution changes due to wetting of the test pipe near the crack on the increase in the crack opening area and leak rate. Two 12-inch straight pipes subjected to both internal pressure and thermal load, but not to bending load, are modelled. The leak rate was found to be very susceptible to the metal temperature of the piping. In leak rate tests, therefore, it is recommended that temperature distribution be measured precisely for a wide area.

Autonomous Cryogenic Leak Detector for Improving Launch Site Operations

NASA Technical Reports Server (NTRS)

Goswami, Kisholoy

2013-01-01

NASA, military, and commercial satellite users need launch services that are highly reliable, less complex, easier to test, and cost effective. This project has developed a tapered optical fiber sensor for detecting hydrogen. The invention involves incorporating chemical indicators on the tapered end of an optical fiber using organically modified silicate nanomaterials. The Hazardous Gas Detection Lab (HGDL) at Kennedy Space Center is involved in the design and development of instrumentation that can detect and qualify various mission-critical chemicals. Historically, hydrogen, helium, nitrogen, oxygen, and argon are the first five gases of HGDL focus. The use of these cryogenic fluids in the area of propulsion offers challenges. Due to their extreme low temperatures, these fluids induce contraction of the materials they contact, a potential cause of leakage. Among them, hydrogen is of particular concern. Small sensors are needed in multiple locations without adding to the structural weight. The most vulnerable parts of the engine are the connection flanges on the transfer lines, which have to support cycles of large thermal amplitude. The thermal protection of the engine provides a closed area, increasing the likelihood of an explosive atmosphere. Thus, even a small leak represents an unacceptable hazardous condition during loading operations, in flight, or after an aborted launch. Tapered fibers were first fabricated from 1/1.3-mm core/cladding (silica/ plastic) optical fibers. Typically a 1-ft (approx. 30- cm) section of the 1-mm fiber is cut from the bundle and marked with a pen into five 2-.-in. (.5.7-cm) sections. A propane torch is applied at every alternate mark to burn the jacket and soften the glass core. While the core is softening, the two ends of the fiber are pulled apart slowly to create fine tapers of .- to .-in. (.6- to 12-mm) long on the 1-mm optical fiber. Following this, the non-tapered ends of the fibers are polished to a 0.3-micron finish

A Small Leak Detection Method Based on VMD Adaptive De-Noising and Ambiguity Correlation Classification Intended for Natural Gas Pipelines.

PubMed

Xiao, Qiyang; Li, Jian; Bai, Zhiliang; Sun, Jiedi; Zhou, Nan; Zeng, Zhoumo

2016-12-13

In this study, a small leak detection method based on variational mode decomposition (VMD) and ambiguity correlation classification (ACC) is proposed. The signals acquired from sensors were decomposed using the VMD, and numerous components were obtained. According to the probability density function (PDF), an adaptive de-noising algorithm based on VMD is proposed for noise component processing and de-noised components reconstruction. Furthermore, the ambiguity function image was employed for analysis of the reconstructed signals. Based on the correlation coefficient, ACC is proposed to detect the small leak of pipeline. The analysis of pipeline leakage signals, using 1 mm and 2 mm leaks, has shown that proposed detection method can detect a small leak accurately and effectively. Moreover, the experimental results have shown that the proposed method achieved better performances than support vector machine (SVM) and back propagation neural network (BP) methods.

Pleural fluid analysis

MedlinePlus

... of fluid that has collected in the pleural space. This is the space between the lining of the outside of the ... the chest. When fluid collects in the pleural space, the condition is called pleural effusion .

Incidence, risk factors and clinical implications of chyle leak after pancreatic surgery.

PubMed

Strobel, O; Brangs, S; Hinz, U; Pausch, T; Hüttner, F J; Diener, M K; Schneider, L; Hackert, T; Büchler, M W

2017-01-01

Chyle leak is a well known but poorly characterized complication after pancreatic surgery. Available data on incidence, risk factors and clinical significance of chyle leak are highly heterogeneous. For this cohort study all patients who underwent pancreatic surgery between January 2008 and December 2012 were identified from a prospective database. Chyle leak was defined as any drainage output with triglyceride content of 110 mg/dl or more. Risk factors for chyle leak were assessed by univariable and multivariable analyses. The clinical relevance of chyle leak was evaluated using hospital stay and resolution by 14 days for short-term outcome and overall survival for long-term outcome. Chyle leak developed in 346 (10·4 per cent) of 3324 patients. Pre-existing diabetes, resection for malignancy, distal pancreatectomy, duration of surgery 180 min or longer, and concomitant pancreatic fistula or abscess were independent risk factors for chyle leak. Both isolated chyle leak and coincidental chyle leak (with other intra-abdominal complications) were associated with prolonged hospital stay. Some 178 (87·7 per cent) of 203 isolated chyle leaks and 90 (70·3 per cent) of 128 coincidental chyle leaks resolved with conservative management within 14 days. Initial and maximum drainage volumes were associated with duration of hospital stay and success of therapy by 14 days. Impact on survival was restricted to chyle leaks that persisted at 14 days in patients with cancer undergoing palliative surgery. Chyle leak is a relevant complication, with an incidence of more than 10 per cent after pancreatic surgery, and has a major impact on hospital stay. Drainage volume is associated with hospital stay and success of therapy. © 2016 BJS Society Ltd Published by John Wiley & Sons Ltd.

Clinical and subclinical leaks after low colorectal anastomosis: a clinical and radiologic study.

PubMed

Lim, Michael; Akhtar, Saleem; Sasapu, Kishore; Harris, Keith; Burke, Dermot; Sagar, Peter; Finan, Paul

2006-10-01

This study was designed to examine the natural history of subclinical leaks and their effect on bowel function and quality of life and to evaluate water-soluble contrast enema features that predict anastomotic healing after leaks. Consecutive patients who underwent low rectal anastomosis were followed up postoperatively for leaks. All leaks were confirmed radiologically with CT scanning and water-soluble contrast enema imaging. Water-soluble contrast enemas were serially repeated to identify healing. Characteristics on initial water-soluble contrast enema were correlated with observed healing. Postoperatively, patients were required to fill in a quality of life and a bowel function questionnaire. A total of 138 patients underwent low rectal anastomosis procedures with a median follow-up period of 26 (interquartile range, 19-37) months. There were 23 documented leaks of which 13 (9 percent) presented clinically and 10 (8 percent) presented subclinically. Ileostomy closure was possible in 4 of 13 (30 percent) patients with a clinical leak and all 10 (100 percent) patients with a subclinical leak. Median quality of life scores were lower for patients with clinical leaks and no ileostomy closure (P = 0.03). Bowel function for subclinical leak patients and clinical leak patients with ileostomy closure were similarly impaired. The presence of a cavity (P = 0.01) and a stricture (P = 0.01) at the anastomotic site were unfavorable radiologic features associated with nonhealing. Subclinical leaks are more benign in their natural history compared with clinical leaks. Quality of life and bowel function is no better in patients with a subclinical leak compared with patients with a clinical leak who have ileostomy closure. Anastomotic leaks may resolve if favorable radiologic features are present.

40 CFR 1066.985 - Fuel storage system leak test procedure.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Fuel storage system leak test... Refueling Emission Test Procedures for Motor Vehicles § 1066.985 Fuel storage system leak test procedure. (a... conditions. (3) Leak test equipment must have the ability to pressurize fuel storage systems to at least 4.1...

[Ryanodine receptor, calcium leak and arrhythmias].

PubMed

Rueda, Angélica; de Alba-Aguayo, David R; Valdivia, Héctor H

2014-01-01

The participation of the ionic Ca(2+) release channel/ryanodine receptor in cardiac excitation-contraction coupling is well known since the late '80s, when various seminal papers communicated its purification for the first time and its identity with the "foot" structures located at the terminal cisternae of the sarcoplasmic reticulum. In addition to its main role as the Ca(2+) channel responsible for the transient Ca(2+) increase that activates the contractile machinery of the cardiomyocytes, the ryanodine receptor releases Ca(2+) during the relaxation phase of the cardiac cycle, giving rise to a diastolic Ca(2+) leak. In normal physiological conditions, diastolic Ca(2+) leak regulates the proper level of luminal Ca(2+), but in pathological conditions it participates in the generation of both, acquired and hereditary arrhythmias. Very recently, several groups have focused their efforts into the development of pharmacological tools to control the altered diastolic Ca(2+) leak via ryanodine receptors. In this review, we focus our interest on describing the participation of cardiac ryanodine receptor in the diastolic Ca(2+) leak under physiological or pathological conditions and also on the therapeutic approaches to control its undesired exacerbated activity during diastole. Copyright © 2013 Instituto Nacional de Cardiología Ignacio Chávez. Published by Masson Doyma México S.A. All rights reserved.

Fatal Primary Capillary Leak Syndrome in a Late Preterm Newborn.

PubMed

Kulihova, Katarina; Prochazkova, Martina; Semberova, Jana; Janota, Jan

2016-10-01

Primary capillary leak syndrome is a rare disease of unknown etiology, characterized by episodes of vascular collapse and plasma extravasation, which may lead to multiple organ failure. Primary capillary leak is extremely rare in children. The authors report a case of a late preterm newborn with fatal capillary leak syndrome of unknown etiology, manifesting as hypotension unresponsive to treatment, extravasation leading to generalised edema, disseminated intravascular coagulation and finally, multiple organ dysfunction syndrome. Aggressive volumotherapy and a combination of inotropes and high doses of terlipressin did not influence systemic vascular collapse and plasma extravasation. The newborn developed multiple organ failure and died on day 27 of life. Investigations performed failed to reveal any specific cause of capillary leak. This is the first report of a fatal primary capillary leak syndrome in a newborn.

Livermore study says oil leaks not severe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patrick, L.

The Petroleum Marketers Association of America (PMAA), which is working to reform the federal Leaking Underground Storage Tank program, got some strong ammunition last month. A study that the Lawrence Livermore National Laboratory performed for the California State Water Resources Control Board has found that the environmental threat of leaks is not as severe as formerly thought. The study said: such leaks rarely jeopardize drinking water; fuel hydrocarbons have limited impacts on health, the environment, and groundwater; and cleanups often are done contrary to the knowledge and experience gained from prior remediations. As a result of the study, Gov. Petemore » Wilson ordered California cleanups halted at sites more than 250 feet from drinking water supplies.« less

40 CFR 1065.644 - Vacuum-decay leak rate.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak rate...

40 CFR 1065.644 - Vacuum-decay leak rate.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak rate...

40 CFR 1065.644 - Vacuum-decay leak rate.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak rate...

40 CFR 1065.644 - Vacuum-decay leak rate.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak rate...

40 CFR 1065.644 - Vacuum-decay leak rate.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak rate...

Accuracy improvement in the TDR-based localization of water leaks

NASA Astrophysics Data System (ADS)

Cataldo, Andrea; De Benedetto, Egidio; Cannazza, Giuseppe; Monti, Giuseppina; Demitri, Christian

A time domain reflectometry (TDR)-based system for the localization of water leaks has been recently developed by the authors. This system, which employs wire-like sensing elements to be installed along the underground pipes, has proven immune to the limitations that affect the traditional, acoustic leak-detection systems. Starting from the positive results obtained thus far, in this work, an improvement of this TDR-based system is proposed. More specifically, the possibility of employing a low-cost, water-absorbing sponge to be placed around the sensing element for enhancing the accuracy in the localization of the leak is addressed. To this purpose, laboratory experiments were carried out mimicking a water leakage condition, and two sensing elements (one embedded in a sponge and one without sponge) were comparatively used to identify the position of the leak through TDR measurements. Results showed that, thanks to the water retention capability of the sponge (which maintains the leaked water more localized), the sensing element embedded in the sponge leads to a higher accuracy in the evaluation of the position of the leak.

Peritoneal fluid analysis

MedlinePlus

... at fluid that has built up in the space in the abdomen around the internal organs. This area is called the peritoneal space. ... sample of fluid is removed from the peritoneal space using a needle and syringe. Ultrasound is often ...

Assessing the Rayleigh Intensity Remote Leak Detection Technique

NASA Technical Reports Server (NTRS)

Clements, Sandra

2001-01-01

Remote sensing technologies are being considered for efficient, low cost gas leak detection. An exploratory project to identify and evaluate remote sensing technologies for application to gas leak detection is underway. During Phase 1 of the project, completed last year, eleven specific techniques were identified for further study. One of these, the Rayleigh Intensity technique, would make use of changes in the light scattered off of gas molecules to detect and locate a leak. During the 10-week Summer Faculty Fellowship Program, the scatter of light off of gas molecules was investigated. The influence of light scattered off of aerosols suspended in the atmosphere was also examined to determine if this would adversely affect leak detection. Results of this study indicate that in unconditioned air, it will be difficult, though perhaps not impossible, to distinguish between a gas leak and natural variations in the aerosol content of the air. Because information about the particle size distribution in clean room environments is incomplete, the applicability in clean rooms is uncertain though more promising than in unconditioned environments. It is suggested that problems caused by aerosols may be overcome by using the Rayleigh Intensity technique in combination with another remote sensing technique, the Rayleigh Doppler technique.

REFLEAK: NIST Leak/Recharge Simulation Program for Refrigerant Mixtures

National Institute of Standards and Technology Data Gateway

SRD 73 NIST REFLEAK: NIST Leak/Recharge Simulation Program for Refrigerant Mixtures (PC database for purchase)   REFLEAK estimates composition changes of zeotropic mixtures in leak and recharge processes.

[Capillary leak syndrome disclosing Ofuji's papuloerythroderma].

PubMed

Carsuzaa, F; Pierre, C; Morand, J J; Farnarier, C; Marrot, F; Kaplanski, G

1996-01-01

Capillary leak syndrome is a specific entity among syndromes with capillary hyperpermeability. Endothelial cell activation is related to the higt level of adhesion molecules (sICAM-1, sVCAM-&, sCD62E) possibly due to several cytokines (IL-2, TNF ...). An 84-year-old woman was hospitalized for erythroderma. Ofujui papuloerythroderma was diagnosed and edema was attributed to capillary leak. A kinetic study of several cytokines and adhesion molecules sCD62E, sVCAM-1 and sICAM-1 was done. Outcome was favorable with corticopuvatherapy. The capillary leak syndrome reported here is simlar to that described in other erythrodermas with or without lymphoma. The keratinocyte would be activated by the CD4 T lymphocyte via the gamma-interferon mediator. The T cell secretes cytokines (interleukin-1, tumor necrosis factor ...) which activates the endothelium and increases vascular permeability. The level of adhesion molecules and changes observed during the episode of edema demonstrated the endothelial activation.

Wavelet analysis of polarization maps of polycrystalline biological fluids networks

NASA Astrophysics Data System (ADS)

Ushenko, Y. A.

2011-12-01

The optical model of human joints synovial fluid is proposed. The statistic (statistic moments), correlation (autocorrelation function) and self-similar (Log-Log dependencies of power spectrum) structure of polarization two-dimensional distributions (polarization maps) of synovial fluid has been analyzed. It has been shown that differentiation of polarization maps of joint synovial fluid with different physiological state samples is expected of scale-discriminative analysis. To mark out of small-scale domain structure of synovial fluid polarization maps, the wavelet analysis has been used. The set of parameters, which characterize statistic, correlation and self-similar structure of wavelet coefficients' distributions of different scales of polarization domains for diagnostics and differentiation of polycrystalline network transformation connected with the pathological processes, has been determined.

Metabolic profiling of body fluids and multivariate data analysis.

PubMed

Trezzi, Jean-Pierre; Jäger, Christian; Galozzi, Sara; Barkovits, Katalin; Marcus, Katrin; Mollenhauer, Brit; Hiller, Karsten

2017-01-01

Metabolome analyses of body fluids are challenging due pre-analytical variations, such as pre-processing delay and temperature, and constant dynamical changes of biochemical processes within the samples. Therefore, proper sample handling starting from the time of collection up to the analysis is crucial to obtain high quality samples and reproducible results. A metabolomics analysis is divided into 4 main steps: 1) Sample collection, 2) Metabolite extraction, 3) Data acquisition and 4) Data analysis. Here, we describe a protocol for gas chromatography coupled to mass spectrometry (GC-MS) based metabolic analysis for biological matrices, especially body fluids. This protocol can be applied on blood serum/plasma, saliva and cerebrospinal fluid (CSF) samples of humans and other vertebrates. It covers sample collection, sample pre-processing, metabolite extraction, GC-MS measurement and guidelines for the subsequent data analysis. Advantages of this protocol include: •Robust and reproducible metabolomics results, taking into account pre-analytical variations that may occur during the sampling process•Small sample volume required•Rapid and cost-effective processing of biological samples•Logistic regression based determination of biomarker signatures for in-depth data analysis.

Prediction of failure pressure and leak rate of stress corrosion.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Majumdar, S.; Kasza, K.; Park, J. Y.

2002-06-24

An ''equivalent rectangular crack'' approach was employed to predict rupture pressures and leak rates through laboratory generated stress corrosion cracks and steam generator tubes removed from the McGuire Nuclear Station. Specimen flaws were sized by post-test fractography in addition to a pre-test advanced eddy current technique. The predicted and observed test data on rupture and leak rate are compared. In general, the test failure pressures and leak rates are closer to those predicted on the basis of fractography than on nondestructive evaluation (NDE). However, the predictions based on NDE results are encouraging, particularly because they have the potential to determinemore » a more detailed geometry of ligamented cracks, from which failure pressure and leak rate can be more accurately predicted. One test specimen displayed a time-dependent increase of leak rate under constant pressure.« less

A Small Leak Detection Method Based on VMD Adaptive De-Noising and Ambiguity Correlation Classification Intended for Natural Gas Pipelines

PubMed Central

Xiao, Qiyang; Li, Jian; Bai, Zhiliang; Sun, Jiedi; Zhou, Nan; Zeng, Zhoumo

2016-01-01

In this study, a small leak detection method based on variational mode decomposition (VMD) and ambiguity correlation classification (ACC) is proposed. The signals acquired from sensors were decomposed using the VMD, and numerous components were obtained. According to the probability density function (PDF), an adaptive de-noising algorithm based on VMD is proposed for noise component processing and de-noised components reconstruction. Furthermore, the ambiguity function image was employed for analysis of the reconstructed signals. Based on the correlation coefficient, ACC is proposed to detect the small leak of pipeline. The analysis of pipeline leakage signals, using 1 mm and 2 mm leaks, has shown that proposed detection method can detect a small leak accurately and effectively. Moreover, the experimental results have shown that the proposed method achieved better performances than support vector machine (SVM) and back propagation neural network (BP) methods. PMID:27983577

Fluid flow measurements by means of vibration monitoring

NASA Astrophysics Data System (ADS)

Campagna, Mauro M.; Dinardo, Giuseppe; Fabbiano, Laura; Vacca, Gaetano

2015-11-01

The achievement of accurate fluid flow measurements is fundamental whenever the control and the monitoring of certain physical quantities governing an industrial process are required. In that case, non-intrusive devices are preferable, but these are often more sophisticated and expensive than those which are more common (such as nozzles, diaphrams, Coriolis flowmeters and so on). In this paper, a novel, non-intrusive, simple and inexpensive methodology is presented to measure the fluid flow rate (in a turbulent regime) whose physical principle is based on the acquisition of transversal vibrational signals induced by the fluid itself onto the pipe walls it is flowing through. Such a principle of operation would permit the use of micro-accelerometers capable of acquiring and transmitting the signals, even by means of wireless technology, to a control room for the monitoring of the process under control. A possible application (whose feasibility will be investigated by the authors in a further study) of this introduced technology is related to the employment of a net of micro-accelerometers to be installed on pipeline networks of aqueducts. This apparatus could lead to the faster and easier detection and location of possible leaks of fluid affecting the pipeline network with more affordable costs. The authors, who have previously proven the linear dependency of the acceleration harmonics amplitude on the flow rate, here discuss an experimental analysis of this functional relation with the variation in the physical properties of the pipe in terms of its diameter and constituent material, to find the eventual limits to the practical application of the measurement methodology.

Apparatus for Leak Testing Pressurized Hoses

NASA Technical Reports Server (NTRS)

Underwood, Steve D. (Inventor); Garrison, Steve G. (Inventor); Gant, Bobby D. (Inventor); Palmer, John R. (Inventor)

2015-01-01

A hose-attaching apparatus for leak-testing a pressurized hose may include a hose-attaching member. A bore may extend through the hose-attaching member. An internal annular cavity may extend coaxially around the bore. At least one of a detector probe hole and a detector probe may be connected to the internal annular cavity. At least a portion of the bore may have a diameter which is at least one of substantially equal to and less than a diameter of a hose to be leak-tested.

Methane Leaks from Natural Gas Systems Follow Extreme Distributions.

PubMed

Brandt, Adam R; Heath, Garvin A; Cooley, Daniel

2016-11-15

Future energy systems may rely on natural gas as a low-cost fuel to support variable renewable power. However, leaking natural gas causes climate damage because methane (CH 4 ) has a high global warming potential. In this study, we use extreme-value theory to explore the distribution of natural gas leak sizes. By analyzing ∼15 000 measurements from 18 prior studies, we show that all available natural gas leakage data sets are statistically heavy-tailed, and that gas leaks are more extremely distributed than other natural and social phenomena. A unifying result is that the largest 5% of leaks typically contribute over 50% of the total leakage volume. While prior studies used log-normal model distributions, we show that log-normal functions poorly represent tail behavior. Our results suggest that published uncertainty ranges of CH 4 emissions are too narrow, and that larger sample sizes are required in future studies to achieve targeted confidence intervals. Additionally, we find that cross-study aggregation of data sets to increase sample size is not recommended due to apparent deviation between sampled populations. Understanding the nature of leak distributions can improve emission estimates, better illustrate their uncertainty, allow prioritization of source categories, and improve sampling design. Also, these data can be used for more effective design of leak detection technologies.

Methane Leaks from Natural Gas Systems Follow Extreme Distributions

DOE PAGES

Brandt, Adam R.; Heath, Garvin A.; Cooley, Daniel

2016-10-14

Future energy systems may rely on natural gas as a low-cost fuel to support variable renewable power. However, leaking natural gas causes climate damage because methane (CH 4) has a high global warming potential. In this study, we use extreme-value theory to explore the distribution of natural gas leak sizes. By analyzing ~15,000 measurements from 18 prior studies, we show that all available natural gas leakage datasets are statistically heavy-tailed, and that gas leaks are more extremely distributed than other natural and social phenomena. A unifying result is that the largest 5% of leaks typically contribute over 50% of themore » total leakage volume. While prior studies used lognormal model distributions, we show that lognormal functions poorly represent tail behavior. Our results suggest that published uncertainty ranges of CH 4 emissions are too narrow, and that larger sample sizes are required in future studies to achieve targeted confidence intervals. Additionally, we find that cross-study aggregation of datasets to increase sample size is not recommended due to apparent deviation between sampled populations. Finally, understanding the nature of leak distributions can improve emission estimates, better illustrate their uncertainty, allow prioritization of source categories, and improve sampling design. Also, these data can be used for more effective design of leak detection technologies.« less

Methane Leaks from Natural Gas Systems Follow Extreme Distributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandt, Adam R.; Heath, Garvin A.; Cooley, Daniel

Future energy systems may rely on natural gas as a low-cost fuel to support variable renewable power. However, leaking natural gas causes climate damage because methane (CH 4) has a high global warming potential. In this study, we use extreme-value theory to explore the distribution of natural gas leak sizes. By analyzing ~15,000 measurements from 18 prior studies, we show that all available natural gas leakage datasets are statistically heavy-tailed, and that gas leaks are more extremely distributed than other natural and social phenomena. A unifying result is that the largest 5% of leaks typically contribute over 50% of themore » total leakage volume. While prior studies used lognormal model distributions, we show that lognormal functions poorly represent tail behavior. Our results suggest that published uncertainty ranges of CH 4 emissions are too narrow, and that larger sample sizes are required in future studies to achieve targeted confidence intervals. Additionally, we find that cross-study aggregation of datasets to increase sample size is not recommended due to apparent deviation between sampled populations. Finally, understanding the nature of leak distributions can improve emission estimates, better illustrate their uncertainty, allow prioritization of source categories, and improve sampling design. Also, these data can be used for more effective design of leak detection technologies.« less

Resilience to Leaking — Dynamic Systems Modeling of Information Security

PubMed Central

Hamacher, Kay

2012-01-01

Leaking of confidential material is a major threat to information security within organizations and to society as a whole. This insight has gained traction in the political realm since the activities of Wikileaks, which hopes to attack ‘unjust’ systems or ‘conspiracies’. Eventually, such threats to information security rely on a biologistic argument on the benefits and drawbacks that uncontrolled leaking might pose for ‘just’ and ‘unjust’ entities. Such biological metaphors are almost exclusively based on the economic advantage of participants. Here, I introduce a mathematical model of the complex dynamics implied by leaking. The complex interactions of adversaries are modeled by coupled logistic equations including network effects of econo-communication networks. The modeling shows, that there might arise situations where the leaking envisioned and encouraged by Wikileaks and the like can strengthen the defending entity (the ‘conspiracy’). In particular, the only severe impact leaking can have on an organization seems to originate in the exploitation of leaks by another entity the organization competes with. Therefore, the model suggests that leaks can be used as a `tactical mean’ in direct adversary relations, but do not necessarily increase public benefit and societal immunization to ‘conspiracies’. Furthermore, within the model the exploitation of the (open) competition between entities seems to be a more promising approach to control malicious organizations : divide-et-impera policies triumph here. PMID:23227151

Overview of MSFC's Applied Fluid Dynamics Analysis Group Activities

NASA Technical Reports Server (NTRS)

Garcia, Roberto; Wang, Tee-See; Griffin, Lisa; Turner, James E. (Technical Monitor)

2001-01-01

This document is a presentation graphic which reviews the activities of the Applied Fluid Dynamics Analysis Group at Marshall Space Flight Center (i.e., Code TD64). The work of this group focused on supporting the space transportation programs. The work of the group is in Computational Fluid Dynamic tool development. This development is driven by hardware design needs. The major applications for the design and analysis tools are: turbines, pumps, propulsion-to-airframe integration, and combustion devices.

Does omental pedicle flap reduce anastomotic leak and septic complications after rectal cancer surgery?

PubMed

Ozben, Volkan; Aytac, Erman; Liu, Xiaobo; Ozuner, Gokhan

2016-03-01

Whether creation of omental pedicle flap (OPF) to reinforce bowel anastomosis can reduce septic outcomes remains controversial. The aim of this study was to investigate the role of this technique on anastomotic leak and septic complications after rectal cancer surgery. Patients who underwent rectal cancer surgery from 01/2008 to 12/2013 were identified and categorized into two groups based on OPF creation versus no-OPF creation. Clinical, operative characteristics and postoperative anastomotic leak and surgical site infections within 30 days after surgery were compared between the groups. There were 65 (14%) and 403 (86%) patients in OPF and no-OPF group, respectively. In multivariate analysis, OPF was not found to be associated with anastomotic leak (p = 0.35), organ/space infections (p = 0.99) and overall surgical site infections (p = 0.65). Three hundred and sixty eight (78.6%) patients underwent diversion. OPF did not reduce septic complications irrespective of the stoma status (p > 0.05). There were no differences between the two groups in terms of operative (p = 0.46) and non-operative management (p = 0.14). OPF neither reduced the incidence of anastomotic leak and surgical site infections nor had any impact on the management of anastomotic leak. Copyright © 2016 IJS Publishing Group Limited. Published by Elsevier Ltd. All rights reserved.

Clinical impact of leak compensation during non-invasive ventilation.

PubMed

Storre, Jan Hendrik; Bohm, Philipp; Dreher, Michael; Windisch, Wolfram

2009-10-01

This study aimed to assess the impact of leak compensation capabilities during pressure- and volume-limited non-invasive positive-pressure ventilation (NPPV) in COPD patients. Fourteen patients with stable hypercapnic COPD who were receiving long-term NPPV were included in the study. For both modes of NPPV, a full face mask and an artificial leak in the ventilatory circuit were used at three different settings, and applied during daytime NPPV, either without leakage (setting I), with leakage during inspiration only (setting II), and with leakage during inspiration and expiration (setting III). Ventilation pattern was pneumotachy-graphically recorded. NPPV was feasible with negligible leak volumes, indicating optimal mask fitting during the daytime (setting I). In the presence of leakage (settings II and III), the attempt to compensate for leak was only evident during pressure-limited NPPV, since inspiratory volumes delivered by the ventilator increased from 726+/-129 (setting I) to 1104+/-164 (setting II), and to 1257+/-166 (setting III) ml during pressure-limited NPPV, respectively (all p<0.001); however, they remained stable during volume-limited NPPV. Leak compensation resulted in a decrease in leakage-induced dyspnea. However, 83%/87% (setting II/III) of the additionally-delivered inspiratory volume during pressure-limited NPPV was also lost via leakage. Expiratory volume was higher in setting II compared to setting III (both p<0.001), indicating the presence of significant expiratory leakage. The attempt at leak compensation largely feeds the leakage itself and only results in a marginal increase of tidal volume. However, pressure-limited--but not volume-limited--NPPV results in a clinically-important leak compensation in vivo. www.uniklinik-freiburg.de/zks/live/uklregister/Oeffentlich.html Identifier: UKF001272.

Transepithelial leak in Barrett's esophagus patients: The role of proton pump inhibitors

PubMed Central

Farrell, Christopher; Morgan, Melissa; Tully, Owen; Wolov, Kevin; Kearney, Keith; Ngo, Benjamin; Mercogliano, Giancarlo; Thornton, James J; Valenzano, Mary Carmen; Mullin, James M

2012-01-01

AIM: To determine if the observed paracellular sucrose leak in Barrett’s esophagus patients is due to their proton pump inhibitor (PPI) use. METHODS: The in vivo sucrose permeability test was administered to healthy controls, to Barrett’s patients and to non-Barrett’s patients on continuous PPI therapy. Degree of leak was tested for correlation with presence of Barrett’s, use of PPIs, and length of Barrett’s segment and duration of PPI use. RESULTS: Barrett’s patients manifested a near 3-fold greater, upper gastrointestinal sucrose leak than healthy controls. A decrease of sucrose leak was observed in Barrett’s patients who ceased PPI use for 7 d. Although initial introduction of PPI use (in a PPI-naïve population) results in dramatic increase in sucrose leak, long-term, continuous PPI use manifested a slow spontaneous decline in leak. The sucrose leak observed in Barrett’s patients showed no correlation to the amount of Barrett’s tissue present in the esophagus. CONCLUSION: Although future research is needed to determine the degree of paracellular leak in actual Barrett’s mucosa, the relatively high degree of leak observed with in vivo sucrose permeability measurement of Barrett’s patients reflects their PPI use and not their Barrett’s tissue per se. PMID:22719187

Supercritical-fluid extraction and chromatography-mass spectrometry for analysis of mycotoxins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, R.D.; Udseth, H.R.

1982-07-01

The use of direct supercritical-fluid injection-mass spectrometry for the rapid analysis of mycotoxins of the tricothecene group is demonstrated. A solution containing diacetoxyscirpenol or T-2 toxin is injected into a fluid consisting primarily of pentane or carbon dioxide and is rapidly brought to supercritical conditions. Direct injection of the fluid stream into a chemical ionization source allows thermally labile compounds to be analyzed. Under these conditions trichothecene mass spectra showing significant (M + 1)/sup +/ ions and distinctive fragmentation patterns are obtained. Detection limits are in the subnanogram range. Direct analysis from complex substrates using selective supercritical-fluid extraction is proposed.more » 4 figures.« less