Drain Location Research Articles

Subdural Versus Subgaleal Drain Placement After Minicraniotomy for Chronic Subdural Hematoma.

Surgical evacuation with placement of a postoperative drain is the standard treatment for symptomatic chronic subdural hematoma (cSDH). Subdural and subgaleal drains are equally effective after burrhole craniostomy, but the optimal location of the drain after craniotomy is not clear. We sought to compare the clinical and radiological outcomes of subdural and subgaleal drain placement in patients undergoing minicraniotomy for cSDH. A retrospective review of 137 consecutive patients undergoing minicraniotomy for cSDH at a single institution was performed. Cases were stratified by location of postoperative drain. The primary outcome was change in functional status (modified Rankin Score, mRS) at 3 months from preoperative baseline. Among the patient cohort, 24.6% received subgaleal drain placement. After a median follow-up of 105 days, 79.4% (27/34) in the subgaleal group and 57.3% (59/103) in the subdural group (P = .02) had been discharged home. Worse premorbid mRS (P = .002), subdural drain location (P = .004), and decreased consciousness at presentation (Glasgow Coma Scale<15) (P < .002) were independent predictors of a discharge destination other than home. At the 3-month follow-up, the subgaleal group exhibited a mean improvement of 0.77 ± 1.2 points, while the subdural group had a deterioration of 0.14 ± 0.8 points (P < .01). Subgaleal drain location (P < .0001), better preoperative Glasgow Coma Scale (P = .01), and worse premorbid mRS (P = .0003) were independent predictors of improved mRS at 3 months. Recurrence requiring repeat surgery were more common in the subdural (13.6% (14/103) than the subgaleal 2.9% (1/34) group, P = .12), although the absolute incidence rates remained low. In patients undergoing minicraniotomy for cSDH, subgaleal drains are associated with shorter hospitalization, greater chance of discharge home, and better functional outcomes than subdural drains.

P.121 Subgaleal versus subdural drain after minicraniotomy for chronic subdural haematoma

Background: Subdural and subgaleal drains are equally effective after burrhole craniostomy for chronic subdural haematoma, however the optimal location of drains after minicraniotomy is not clear. As such we present the first study to assess this. Methods: Consecutive patients undergoing minicraniotomy for cSDH between 2019 and 2023 at a single institution were included. Subgaleal drains were placed exclusively by a single surgeon with the rest of the department utilising standard subdural drains. Cases were stratified by drain location. Primary outcomes included changes in functional status (Modified Rankin Score, mRS) at 3 months from preoperative baseline. Results: A total of 137 patients were included, of which 24.6% received subgaleal drains. Discharge home was higher in the subgaleal group compared to subdural group (79.4% vs 57.3%, p=0.02). Subgaleal drain location (p&lt;0.0001) and better preoperative GCS (p=0.01) were predictors of improved 3 month mRS. Worse premorbid mRS (p=0.002), subdural drain (p=0.004), and decreased consciousness at presentation (p&lt;0.002) were predictors of not being discharged home. Surgical recurrence was lower in the subgaleal group than the subdural group (2.9% vs 13.6%, p=0.12), but not statistically significant. Conclusions: Subgaleal drains are associated with shorter hospitalisation, greater chance of discharge home, and better functional outcomes than subdural drains.

Impact of intense sanitization on environmental biofilm communities and the survival of Salmonella enterica at a beef processing plant.

Salmonella enterica is a leading cause of foodborne illness in the U.S. In the meat industry, one action taken to address pathogen contamination incidence is an intense sanitization (IS) of the entire processing plant that many large processors perform annually or semiannually. However, this procedure's immediate and long-term impact on environment microbial community and pathogen colonization are unknown. Here we investigated the impact of IS procedure on environmental biofilms and the subsequent S. enterica colonization and stress tolerance. Environmental samples were collected from floor drains at various areas 1 week before, 1 week, and 4 weeks after the IS procedure at a beef plant with sporadic S. enterica prevalence. Biofilm formation by microorganisms in the drain samples without S. enterica presence was tested under processing temperature. The ability of the biofilms to recruit and/or protect a co-inoculated S. enterica strain from quaternary ammonium compound (QAC) treatment was determined. The community structure of each drain sample was elucidated through 16S rRNA amplicon community sequencing. Post-IS samples collected from 8 drains formed significantly stronger biofilms than the respective pre-IS samples. S. enterica colonization was not different between the pre- and post-IS biofilms at all drain locations. S. enterica survival in QAC-treated pre- and post-IS mixed biofilms varied depending upon the drain location but a higher survival was associated with a stronger biofilm matrix. The 16S rRNA amplicon gene community sequencing results exhibited a decrease in community diversity 1 week after IS treatment but followed by a significant increase 4 weeks after the treatment. The IS procedure also significantly altered the community composition and the higher presence of certain species in the post-IS community may be associated with the stronger mixed biofilm formation and Salmonella tolerance. Our study suggested that the IS procedure might disrupt the existing environmental microbial community and alter the natural population composition, which might lead to unintended consequences as a result of a lack of competition within the multispecies mixture. The survival and recruitment of species with high colonizing capability to the post-IS community may play crucial roles in shaping the ensuing ecological dynamics.

Vertical transmission of infectious aerosols through building toilet drainage system: An experimental study

The building's toilet drainage system has been identified as a potential route for the transmission of SARS-CoV-2 during outbreaks. This study employed agar-fluorescein sodium semi-solid as trace particles to investigate the possibility of vertical transmission of the SARS-CoV-2 in drainage system. In both scenarios, where floor drains were all properly sealed or dried out, simulated faeces containing fluorescein sodium were flushed into the toilet bowl. Air sampling was conducted in each restroom, and differential pressure measurements at the floor drain locations were taken. The experimental results showed that when all floor drains were properly sealed, the differential pressure at each floor drain was 0. The fluorescein sodium-traced aerosol did not transmit through the drainage system to various floors, which significantly reduced the risk of infection for users through this route. However, when all floor drains dried out, toilet users above the neutral pressure layer (NPL) were at a high risk of virus infection. Due to the increasing maximum negative pressure at the floor drain above the NPL with ascending floor levels, users on each floor above the NPL faced an elevated infection risk in restrooms. Specifically, users on the top floor were exposed to infectious aerosols roughly 1.6 times that of the first floor above the NPL. Conversely, owing to the increasing maximum positive pressure at the floor drain below the NPL with descending floor levels, users below the NPL experienced a comparatively lower infection risk. This finding has important implications for understanding the vertical transmission dynamics of SARS-CoV-2 in residential or public building and can inform the development of effective control measures.

Evaluation of complications and long-term outcomes associated with 101 dogs and cats discharged with and without subcutaneous active closed-suction drains (2014-2022).

To retrospectively evaluate complications reported in dogs and cats with a closed suction subcutaneous drain that were either managed completely in hospital (Group ND) or discharged home for ongoing outpatient care (Group D). 101 client-owned animals involving 94 dogs and 7 cats with a subcutaneous closed suction drain placed during a surgical procedure. Electronic medical records (January 2014 to December 2022) were reviewed. Signalment, reason for drain placement, surgical procedure, location and duration of drain placement, drain discharge status, antimicrobial usage, culture and sensitivity results, and intraoperative and postoperative complications were recorded. Associations among variables were evaluated. There were 77 animals in Group D and 24 animals in Group ND. Majority (n = 21/26) of complications were classified as minor and were all from Group D. Length of hospitalization in Group D (1 day) was significantly shorter than Group ND (3.25 days). Duration of drain placement was significantly longer in Group D (5.6 days) than Group ND (3.1 days). There were no associations between drain location, drain duration, or surgical site contamination with risk of complications. There is a higher risk of complications associated with discharging an animal from hospital (37%) with a subcutaneous closed suction drain than removing it prior to discharge (4%). These complications, however, were primarily minor and easily managed. Discharging an otherwise stable animal to home with a subcutaneous closed suction drain may be feasible to decrease duration of hospitalization, cost to the owner, and stress for the animal.

Effect Location of Vertical Drain on Seepage and Stability in Homogenous Earth Dams

Effect Location of Vertical Drain on Seepage and Stability in Homogenous Earth Dams

Comparing alternative conceptual models for tile drains and soil heterogeneity for the simulation of tile drainage in agricultural catchments

• The seepage node concept was used to simulate tile drainage at the catchment scale. • Tile drainage was simulated without the specific location of tile drains. • Similar drainage discharge volumes were simulated with different conceptual models. • Drainage discharge was sensitive to soil heterogeneity. • Observed stream discharge and depth to water table were well simulated. Tile drains are important water flow paths in agricultural catchments and must be included in hydrological models. However, their locations are rarely known and the explicit incorporation of tile drains in hydrological models requires refined meshes around the drains, which can significantly increase computational times. Although seepage nodes have been used to represent tile drains with satisfactory performance, they have never been applied to represent all tile drainage systems in a catchment. The goal of this study is to compare different conceptual models for tile drains and soil heterogeneity for the numerical simulation of tile drainage in an agricultural catchment in Denmark. The first conceptual model for tile drains uses seepage nodes to represent only the main collector drains in the catchment and the second model uses seepage nodes distributed over all the agricultural areas, without considering the specific locations of tile drains. A third conceptual model, labelled the Benchmark Model, represent all tile drains at their known locations with seepage nodes and a fourth conceptual model implicitly represents tile drains as a high-permeability layer. The four models performed satisfactorily to simulate the observed outlet stream discharge and could be recommended almost interchangeably. The simulation of the water table depth was very satisfactory compared to modeling studies with similar mesh resolution (∼50 m). Results indicated that the three models using seepage nodes i) simulated similar monthly discharges and cumulative discharge volumes for most of the studied tile-drained areas, and ii) simulated surface water flow in tile-drained fields without runoff or ponding water. The shorter simulation times (around 35% faster) of the model representing the main drains and the distributed seepage node model suggest that they are suitable for model calibration, compared to the Benchmark Model. Whenever the location of tile drains is unavailable, using seepage node to represent drains in agricultural areas may satisfactorily simulate catchment-scale stream and drainage discharges. Four alternative soil models were developed to evaluate the effect of soil heterogeneity on the simulations. Our results suggest that at smaller scales (drainage area) soil heterogeneity is more relevant than the drainage conceptualization to improve model results. However, at the subcatchment scale, the opposite was observed and, at the catchment scale, both criteria had a comparable effect.

Management of postoperative drainage after pancreaticoduodenectomy: review from the location of perianastomotic fluid collection during the early postoperative period

Introduction: To assess the association between perianastomotic fluid collection (PFC) during the early postoperative period and postoperative pancreatic fistula (POPF) related complications, and to investigate the optical drain location. Methods: Medical records of 148 patients who had undergone PD and computed tomography (CT) on postoperative day 4 were retrospectively reviewed. The location—superior, inferior, ventral, dorsal, or splenic hilum—and volume of PFC were determined using CT. Postoperative complications were compared between the PFC and non-PFC groups. Association between volume and postoperative complications was assessed. Results: The PFC group included 102 patients (69%). POPF and organ/space surgical site infection (SSI) were more frequent in the PFC group (p < 0.001 and p=0.020, respectively). According to the location of PFC, superior and ventral PFCs were associated with pseudoaneurysm (p=0.006 and p=0.002, respectively), while inferior and dorsal PFCs were associated with deep incisional SSI (p=0.027 and p=0.034, respectively). In 5 of 9 patients with inferior PFC and deep incisional SSI, the PFC had reached the abdominal wall via the surface of the transverse mesocolon. All of these patients showed a dorsal PFC connected to the inferior PFC on CT performed on POD 4. Therefore, we added drainage tube at the inferior part of PJ for soft pancreas cases after January 2019. We encountered clinically relevant POPF in 3 cases of 10 soft pancreas cases, however we did not experience deep incisional SSI. Conclusion: The prevention of PFC during the early postoperative period may prevent more severe POPF related complications.

Impact of mixed biofilm formation with environmental microorganisms on E. coli O157:H7 survival against sanitization

Biofilm formation by foodborne pathogens is a serious threat to food safety and public health. Meat processing plants may harbor various microorganisms and occasional foodborne pathogens; thus, the environmental microbial community might impact pathogen survival via mixed biofilm formation. We collected floor drain samples from two beef plants with different E. coli O157:H7 prevalence history and investigated the effects of the environmental microorganisms on pathogen sanitizer tolerance. The results showed that biofilm forming ability and bacterial species composition varied considerably based on the plants and drain locations. E. coli O157:H7 cells obtained significantly higher sanitizer tolerance in mixed biofilms by samples from the plant with recurrent E. coli O157:H7 prevalence than those mixed with samples from the other plant. The mixed biofilm that best protected E. coli O157:H7 also had the highest species diversity. The percentages of the species were altered significantly after sanitization, suggesting that the community composition affects the role and tolerance level of each individual species. Therefore, the unique environmental microbial community, their ability to form biofilms on contact surfaces and the interspecies interactions all play roles in E. coli O157:H7 persistence by either enhancing or reducing pathogen survival within the biofilm community.

Drain type and technique for subdural insertion after burr hole evacuation of chronic subdural hematoma.

Strengths and limitations of subdural versus subperiosteal drain location after burr hole evacuation of chronic subdural hematoma (CSDH) are currently debated. The safety of subdural placement of a drain has been questioned in a recent study by Soleman et al. from 2019, showing a misplacement rate of 17%, and these results have been further highlighted by the same authors, with a slightly lower misplacement rate of 15.8%, in the recent paper "When the drain hits the brain." The safety of subdural drainage for CSDH depends to a high degree on type of drain and surgical technique. In this technical note, we describe drain type and technique for drain placement which is standardized in Denmark.

A New Energy Efficient Multitier Deterministic Energy-Efficient Clustering Routing Protocol for Wireless Sensor Networks

Wireless Sensor Networks (WSNs) may be incorporated with thousands of small nodes. This gives them the capability to effectively sense, communicate, and compute parameters. However, the security and life span of a WSN node is a primary concern. This paper is focused on introducing a mathematical model of a modified Multitier Deterministic Energy-Efficient Clustering (DEC) based on novel election multi-tier random probability protocol for agricultural WSNs to enhance the life span of a WSN node along with a comparison of it with existing DEC protocol. In the proposed model, the selection of cluster heads, (CH), is done based on the energy drain pattern and location of the sensor nodes, which increased the lifespan of sensor nodes. In addition, several WSN probabilistic routing protocols to save energy throughout data transmissions like Low Energy Adaptive Clustering Hierarchy (LEACH), Power-Efficient Gathering in Sensor Information Systems (PEGASIS), DEC, and Stable Election Protocol (SEP) are explained. Moreover, it has been found that, after some mathematical modification in existing DEC routing, it will be capable to give a more positive result and reduce the energy drain in WSN nodes using a selective cluster head technique based on residual energy of sensor nodes. The DEC protocol is also compared with our proposed modified protocol for showing the energy-efficiency. The energy efficiency of clustering is associated with the field of energy sustainability of wireless sensor networks which is in the scope of Symmetry journal.

The location of perianastomotic fluid collection predicts postoperative complications after pancreaticoduodenectomy.

Perianastomotic fluid collection (PFC) is one of the postoperative complications of pancreaticoduodenectomy (PD). However, no studies have investigated the clinical significance of PFC location and volume during the early postoperative period. This study aimed to assess the association between PFC during the early postoperative period and postoperative complications. Medical records of 148 patients who had undergone PD and computed tomography (CT) on postoperative day 4 were retrospectively reviewed. The location-superior, inferior, ventral, dorsal, or splenic hilum-and PFC index, which is the estimated volume of fluid collection, were determined using CT. The associations between postoperative complication and the presence of PFC, and PFC index according to the location, were assessed. The PFC group included 102 patients (69%). Postoperative pancreatic fistula (POPF) and organ/space surgical site infection (SSI) were more frequent in the PFC group (42% vs 9%, p < 0.001 and 29% vs 11%, p = 0.020, respectively). Additionally, the PFC index was larger in patients who developed POPF, organ/space SSI, or pseudoaneurysm (81cm3 vs 19cm3, p < 0.001; 75cm3 vs 30cm3, p = 0.001; and 185cm3 vs 31cm3, p < 0.001, respectively). Furthermore, superior and ventral PFCs were associated with pseudoaneurysm (11% vs 0%, p = 0.006 and 14% vs 1%, p = 0.002, respectively), whereas inferior and dorsal PFCs were associated with deep incisional SSI (9% vs 0%, p = 0.027 and 8% vs 1%, p = 0.034, respectively). The PFC location during the early postoperative period is associated with postoperative complications. Our findings may help determine the optimal location of prophylactic drains.

Improved background and clutter reduction for pipe detection under pavement using Ground Penetrating Radar (GPR)

Pavement drainage systems are one of the key drivers of pavement function and longevity, and effective drain maintenance can significantly extend a pavement’s service life. Maintenance of these drains, however, is often hampered by the challenge of locating the drains. Ground Penetrating Radar (GPR) typically offers a rapid and effective method to detect these underground targets. However, typical detection schema that rely upon the observation of the hyperbolic return from a GPR scan of a buried conduit still tend to miss many of the older drains beneath pavements as they may be partially or fully filled with sediment and/or may be fabricated from clay or other earthen materials, yielding a return signal that is convolved with significant background noise.To manage this challenge, this paper puts forward an improved background noise and clutter reduction method to enhance the target signals in what amounts to a constructed environment that tends to have more consistent subsurface properties than one might encounter in a general setting. Within this technique, two major algorithms are employed. Algorithm 1 is the core of this method, and plays the role of reducing background noise and clutter. Algorithm 2 is supplementary, and helps eliminate anomalous discontinuous returns generated by the equipment itself, which could otherwise lead to false detection indications in the output of Algorithm 1. Instead of traditional 2-D GPR images, the result of the proposed algorithms is a 1-D plot along the survey line, highlighting a set of “points of interest” that could indicate buried drain locations identified at any given GPR operating frequency. Subsurface exploration using two different operating frequencies, 900 MHz and 400 MHz herein, is then employed to further enhance detection confidence. Points of interest are ultimately coded to define the confidence of the detection. Code -1 represents a false alarm; code 0 represents a possible drain location that needs further examination; codes 1, 2 and 3 represent successful detection with different levels of confidence. Comparing the final result of proposed algorithms with the original GPR images, the improved algorithm is demonstrated to provide significantly improved detection results, and could potentially be applied to similar problems in other contexts.

Surgical Closed Suction Drain Use After Craniotomy for Evacuation of Supratentorial Epidural Hematomas: A Case Series of Radiographic and Clinical Outcomes

Surgical closed suction drain (SCSDs) are used in a variety of surgical disciplines to prevent postoperative fluid collections. Use of SCSDs has not been well studied in the neurosurgical literature. Practice patterns have varied within our institution with respect to SCSDs after craniotomies for neurotrauma. In this study we describe SCSD use for patients undergoing evacuation of supratentorial epidural hematomas (EDHs) and examine the effect on patient outcomes and length of hospital stay. We performed a retrospective review of craniotomies for supratentorial EDH performed at our Level I trauma center between May 2015 and May 2018. Imaging and clinical data were obtained from chart review. Fifty-two patients with EDH received operations from 8 attending surgeons. The number of drains used was 0 or 1 in 36 cases and 2 or more in 16 cases. Drain location was subgaleal in 25 cases, epidural in 8 cases, and both subgaleal and epidural in 13 cases. Attending preference (P < 0.001) but not hematoma size was associated with use of an epidural drain and use of 2 or more drains. After controlling for age, initial neurologic exam, and presence of other injuries, use of more drains was associated with longer intensive care unit lengths of stay. Drain use pattern was not associated with patient outcome measures, and no return to the operating room was necessary for residual or recurrent EDH. Use of fewer SCSDs did not affect radiographic outcome after evacuation of epidural hematomas but was associated with decreased intensive care unit length of stay.

Does Drain Position and Duration Influence Outcomes in Patients Undergoing Burr-Hole Evacuation of Chronic Subdural Hematoma? Lessons from a UK Multicenter Prospective Cohort Study.

BackgroundDrain insertion following chronic subdural hematoma (CSDH) evacuation improves patient outcomes.ObjectiveTo examine whether this is influenced by variation in drain location, positioning or duration of placement.MethodsWe performed a subgroup analysis of a previously reported multicenter, prospective cohort study of CSDH patients performed between May 2013 and January 2014. Data were analyzed relating drain location (subdural or subgaleal), position (through a frontal or parietal burr hole), and duration of insertion, to outcomes in patients aged >16 yr undergoing burr-hole drainage of primary CSDH. Primary outcomes comprised modified Rankin scale (mRS) at discharge and symptomatic recurrence requiring redrainage within 60 d.ResultsA total of 577 patients were analyzed. The recurrence rate of 6.7% (12/160) in the frontal subdural drain group was comparable to 8.8% (30/343) in the parietal subdural drain group. Only 44/577 (7.6%) patients underwent subgaleal drain insertion. Recurrence rates were comparable between subdural (7.7%; 41/533) and subgaleal (9.1%; 4/44) groups (P = .95). We found no significant differences in discharge mRS between these groups. Recurrence rates were comparable between patients with postoperative drainage for 1 or 2 d, 6.4% and 8.4%, respectively (P = .44). There was no significant difference in mRS scores between these 2 groups (P = .56).CONCLUSIONDrain insertion after CSDH drainage is important, but position (subgaleal or subdural) and duration did not appear to influence recurrence rate or clinical outcomes. Similarly, drain location did not influence recurrence rate nor outcomes where both parietal and frontal burr holes were made. Further prospective cohort studies or randomized controlled trials could provide further clarification.

Subdural versus subgaleal drainage for chronic subdural hematomas: a post hoc analysis of the TOSCAN trial.

The use of subdural drains after surgical evacuation of chronic subdural hematoma (CSH) decreases the risk of recurrence and has become the standard of care. Halfway through the controlled, randomized TOSCAN (Randomized Trial of Follow-up CT after Evacuation of Chronic Subdural Hematoma) trial, the authors' institutional guidelines changed to recommend subgaleal instead of subdural drainage. The authors report a post hoc analysis on the influence of drain location in patients participating in the TOSCAN trial. The study involved 361 patients enrolled in the TOSCAN trial. The patients were stratified according to whether they received surgery before (cohort A) or after (cohort B) the change in institutional protocol. An intention-to-treat analysis was performed with surgery for recurrence as the primary endpoint. Secondary endpoints were outcome-based on modified Rankin Scale scores, seizures, infections, parenchymal brain injuries, and hematoma diameter. Of the 361 patients included in the analysis, 214 were stratified into cohort A (subdural drainage recommended), while 147 were stratified into cohort B (subgaleal drainage recommended). There was a 31.78% rate of crossover from the subdural to the subgaleal drainage insertion site due to technical or anatomical difficulties. No differences in the rates of reoperation (21.5% [cohort A] vs 25.17% [cohort B], OR 0.81, 95% CI 0.50-1.34, p = 0.415), infections (0.47% [cohort A] vs 2.04% [cohort B], OR 0.23, 95% CI 0.02-2.19, p = 0.199), seizures (3.27% [cohort A] vs 2.72% [cohort B], OR 1.21, 95% CI 0.35-4.21, p = 0.765), or favorable outcomes (modified Rankin Scale score 0-3) at 1 and 6 months (91.26% [cohort A] vs 96.43% [cohort B], OR 0.39, 95% CI 0.14-1.07, p = 0.067; 89.90% [cohort A] vs 91.55% [cohort B], OR 0.82, 95% CI 0.39-1.73, p = 0.605) were noted between the two cohorts. Postoperatively, patients in cohort A had more frequent parenchymal brain tissue injuries (2.8% vs 0%, p = 0.041). Postoperative absolute and relative hematoma reduction was similar irrespective of the location of the drain. Subgaleal rather than subdural placement of the drain did not increase the risk for reoperation for recurrence of CSHs, nor did it have a negative impact on clinical or radiological outcome. The intention to place a subdural drain was associated with a higher rate of parenchymal injuries.

Evaluation of the Results of Glaucoma Surgery Using Optical Coherent Tomography (Literature Review)

Optical coherence tomography (OCT) is a noncontact method that provides two-dimensional (three-dimensional for some models) highresolution images of the anterior eye segment, with an axial resolution in the range from 3 to 20 µm. Two OCT diagnostics platforms are available: time-domain and spectral OCT. OCT provides a qualitative and quantitative assessment of the most important structures involved in the glaucoma pathogenesis: the state of the optic nerve head, the thickness of the nerve fiber layer, the anterior chamber angle and the trabecular apparatus. The OCT advantage is the ability to visualize surgically formed outflow tracts in the early postoperative period after antiglaucoma surgery. The OCT studies of the antiglaucomatous surgery zone are presented in detail in the literature, namely, the assessment of such biometric parameters of filtering bleb (FB) as wall thickness and reflectivity, radial length and height. According to the literature, the presence of a multi-layer filtration cushion 6 months after the operation indicates a favorable prognosis for the duration of the hypotensive effect of the operation. Such signs as low reflectivity of the filtration cushion wall and the presence of episcleral fluid are in most cases associated with a successful outcome of trabeculectomy. OCT studies of a filtration cushion after trabeculectomy make it much easier to choose an area for revision and nidling. In addition, OCT is used to assess anatomical features in the field of surgical intervention with drains and drainage devices. Currently OCT is widely implemented at the prehospital stage, however, engineers did not stop at the achieved level and carried out the integration of spectral OCT with an operating microscope. The possibilities of intraoperative imaging with cataract phacoemulsification (FEC) and trabeculectomy, implantation of the Ahmed valve, reconstruction of the anterior chamber angle, revision of the filtration bag and nidlinge are described in the literature. Conclusion. OCT is a very valuable method of intravital imaging of the antiglaucoma operation zone. It allows assessing the level of retention of intraocular fluid, determining the functional activity, the location of drains and drainage devices both in the early and late postoperative period.

The symmetric draining of capillary liquids from containers with interior corners

A new lubrication model solution is found for the late-stage draining of a wetting capillary liquid from a linear interior corner. The solution exploits the symmetry of volumetric sink conditions at opposing ends of such a ‘double-drained’ interior corner flow with applications ranging from liquid recovery in microfluidic devices on Earth to liquid fuel scavenging in large fuel tanks aboard spacecraft. At long times $t$, the nominal liquid depth is $h\sim t^{-1}$, the liquid volume is $V\sim t^{-2}$ and the maximum volumetric liquid removal rate is $Q\sim t^{-3}$. The constraints under which the solution is valid are provided. To qualitatively assess the value of the solution, representative experiments are conducted at larger length scales aboard the International Space Station and at microfluidic length scales in a terrestrial laboratory. Both sets of experiments confirm the predicted power-law dependences. We show that the separation of variables solution offers a method to predict maximum drain rates from related geometries where a single drain location provides the required symmetry of the problem.

Design approach for interceptor tile drains using hydrus

Abstract Seepage from irrigation canals can be controlled by interceptor pipe drains located down slope of the canal embankment and parallel to the canal. HYDRUS (2D/3D) is a software that simulates water flow in two-dimensional variably-saturated porous media. This software is used to determine the average water contents of the upper layers, direction of flow and the seepage rate to the pipe drain for different values of evaporation rates, pipe diameters, and horizontal and vertical pipe offsets from the conveyance canal. The results showed that increasing the vertical offset (drain depth) increases the drain discharge. Moreover, increasing the horizontal offset reduces the canal seepage and lower the phreatic surface. The proposed approach can determine drain size and location to cut off canal seepage, ensuring no contribution to the water body under the irrigated lands beyond the drain. The approach accounts for realistic soil formations and considers both saturated and capillary flows.

Does low level of drain amylase warrant the absence of postoperative pancreatic fistula after laparoscopic distal pancreatectomy?

Introduction: The definition of postoperative pancreatic fistula (POPF) by the international study group in pancreatic surgery (ISGPS) is based on the drainage amylase level. However, this definition is valid as long as abdominal drains are well positioned around the pancreatic anastomosis or stump. The aim of this study is to evaluate postoperative outcomes and the location of drains in postoperative computed tomography (CT) scan in patients with low level of the drainage amylase after laparoscopic distal pancreatectomy. Methods: Among 250 patients who underwent LDP from January 2004 to December 2016, 181 patients in whom drain amylase and postoperative CT scan were checked were selected for this study. Results: Eighty-three (43.7%) patients had a low level of drainage amylase (<300 U/L), of whom 38 had malpositioned drains. Among those, 13 (15.7%) patients experienced complicated intra-abdominal fluid collection (defined when associated with fever or leukocytosis, and required antibiotics or percutaneous/endoscopic intervention). CT revealed that the drain was migrated away from the pancreatic stump in 9 patients and well positioned in 4 patients. Percutaneous drainage was required for complicated fluid collection in 12 patients, of whom 9 patients were newly diagnosed to have grade B POPF due to high amylase level in percutaneous drainage. Finally, the incidence of grade B POPF was 18.8% (n=34). Conclusions: The results suggest that ISGPS definition of POPF based on the criteria of the drainage amylase level has some limitation in application to distal pancreatectomy due to frequent malposition or malfunction of the abdominal drain.