Inlet Obstruction Research Articles

Measurement of Disease Activity of Pouchitis.

Pouchitis is the most common inflammatory complication in ulcerative colitis patients undergoing postoperative construction of an IPAA. Pouchitis refers to a spectrum of diseases, and as such, it lacks a universally accepted definition as well as validated instruments to measure disease activity and treatment response. Assessing pouchitis activity is challenging, and methods for diagnosis and classification of severity of pouchitis are not universally agreed upon. Pouchitis is characterized by a constellation of clinical symptoms, including increased stool frequency, urgency, incontinence, bleeding, and rarely constitutional symptoms such as malaise and low-grade fever. However, these symptoms are subjective, and similar symptoms can be caused by noninflammatory conditions including anal sphincter dysfunction, anastomotic strictures, occult leaks, pouch inlet obstruction, and cuffitis. Objective scores that include endoscopic and histologic criteria have been developed for subjects with an IPAA. However, these instruments are not validated for measuring pouchitis disease activity and are associated with a number of challenges. In addition, the clinical components of the scores correlate poorly with endoscopic and histologic findings. There is a need for prospective studies to facilitate the development and validation of novel instruments that are valid, reliable, and responsive to change that would facilitate the development of therapeutic agents for the treatment of pouchitis.

Investigation on inlet obstruction in transitional flow regime: Heat transfer augmentation and pressure drop analysis

Thermohydraulic characteristics of air as the working medium in a circular heated channel fitted with inlet obstruction (ribbed prism) at the inlet is carried out experimentally for transitional flow regime. The ribbed prism is fabricated using aluminum metal. Three non-dimensional parameters clearance ratio (C = 0.4, 0.5 and 0.6) and pitch ratio (e = 0.12, 0.15 and 0.16) were investigated. The Reynolds number (Nu) varied from 500 to 7036 to cover all the flow regimes. Experiments were conducted at two constant heat fluxes of 0.5 kW/m 2 and 1 kW/m 2 . It was found that start and end of transitional flow regime was influenced by insertion of the inlet obstruction at the inlet of the test section. With placement of prism in the channel, the boundaries of transition changes when compared with the plain channel. It is observed that transition starts early and also end early to the transition limit of plain channel. Heat flux shows significant influence on the onset and termination of the transition. At higher heat flux the transition starts later and terminates later when compared with the lower heat flux conditions. For the case of C = 0.6 and e = 0.16, the transition begins Re = 1648 and ends at Re = 3387 for 1 kw/m 2 heat flux. The transition of 0.5 kW/m 2 of heat flux for C = 0.6 and e = 0.16 begins at Re = 1554 and ends at Re = 3321. Correlations were also developed for predicting the Nusselt number and friction factor and the results are useful to design solar thermal systems and heat exchangers.

Venous Collateral Pathways in Superior Thoracic Inlet Obstruction: A Systematic Analysis of Anatomy, Embryology, and Resulting Patterns.

OBJECTIVE. For this study, we reviewed 56 standard-of-care CT examinations over a timespan of 2 years from patients with superior thoracic inlet venous obstruction and identified eight thoracic collateral pathways for venous blood return to the right heart. We evaluated each pathway individually from an anatomic and a pathophysiologic perspective for a better understanding of how such pathways form and what patterns can be expected. MATERIALS AND METHODS. All 56 patients were scanned according to our standard CT protocol. Images of the thoracic region were acquired in the craniocaudal direction during breath-holding using a second-generation dual-source CT scanner. Contrast medium was administered via a cubital or antecubital vein; the amount of contrast material ranged from 49 to 81 mL depending on patient body weight. RESULTS. Of the 56 patients, CT showed superior vena cava syndrome exclusively in 22 (39%) patients and showed superior vena cava syndrome and involvement of the left or right brachiocephalic vein or even the subclavian vein in the remaining 34 (61%) patients. We could not find any remarkable feature leading to the formation of only one collateral pathway or to a specific pattern depending on underlying cause or the level or the extent of obstruction. Thus, we believe that there are no specific patterns for how these venous detours form and that they are most probably driven by pressure gradients. CONCLUSION. Recognizing imaging findings associated with venous collateral pathways may prevent misdiagnosis or unnecessary follow-up examinations. Furthermore, knowledge of these collateral pathways and an understanding of the underlying cause can support interventional radiologists and vascular surgeons in planning interventional procedures and revascularization procedures.

Surgical solutions for refractory J-pouch inlet obstruction.

Many surgeons consider total proctectomy with ileal pouch-anal anastomosis as the treatment of choice for patients with medically refractory ulcerative colitis or ulcerative colitis with dysplasia. However, obstruction occurring at the pouch inlet or involving the afferent limb can be refractory to nonoperative or endoscopic management. Historically, these refractory obstructions have usually required resection of the pouch. There is now increasing evidence to suggest that pouch salvage surgery may be feasible in these patients. A retrospective review was performed of all patients of a single surgical practice who underwent a neo ileal-pouch anastomosis for J-pouch inlet obstructions between 2000 and 2017. Data collected included patient demographics, preoperative workup, intra-operative findings, type of surgical intervention and postoperative outcomes. Surgical interventions were performed on eight patients with J-pouch inlet obstructions. Six patients had inlet strictures or acute angulations at the inlet, which were either bypassed or resected and primarilyanastomosed. Two patients had internal hernias posterior to the mesentery, with volvulus of the pouch. At a mean follow-up of 36.5months, all patients retained their pouches and the mean number of daily bowel movements was eight. Two major and two minor complications occurred. J-pouch inlet obstructions may take years to develop. In patients with obstruction who are refractory to endoscopic or medical treatment, good functional results may be obtained with pouch salvage procedures. With increasing numbers of J-pouches being performed, awareness of novel surgical techniques is important.

Investigation of the Performance and Flow Behaviors of the Multi-blade Centrifugal Fan Based on the Computer Simulation Technology

The non-uniform flowrate distribution along the axis direction will affect the aerodynamic performance of the multi-blade centrifugal fan. In this article, the bevel cutting design on the blade is adopted. Using this method, the inlet structure is changed and the deviation of the inlet flow of the centrifugal fan is improved. The changed inlet structure reduces the friction and the inlet obstruction, which leads to a more uniform flow distribution, and reduces the impact loss, vortex loss and the drag loss. This paper is focused on the effect of bevel cutting blade on the aerodynamic performance and the flow behaviors of the centrifugal fan, and the bevel cutting area moves along the radial direction and axis direction are also investigated based on the CFD simulation, respectively.

Fecal Impaction with a Twist: A Unique Case of Esophageal Inlet Obstruction

Copyright: © 2015 Omar H et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. *Corresponding author: Hina Omar, Advocate Lutheran General Hospital, Internal Medicine, 1775 Dempster Street, Park Ridge, IL 60068, USA, Tel: 847-723-2210; E-mail: hina.omar@gmail.com

Airway Management in an Adult Patient With a Large Vallecular Cyst

Vallecular cysts are rarely seen in adults and occur as a result of the tongue base mucus retention. In cases with laryngeal inlet obstruction due to a vallecular cyst, the airway management sometimes might be a challenge. We presented the airway management of an adult patient with difficult airway due to a large vallecular cyst. A 28-year-old male patient with a large vallecular cyst was scheduled for surgical excision of the cyst under general anesthesia. Despite the use of different laryngoscopic blades, no laryngeal structure was seen due to the cystic formation. After aspiration of approximately 20 mL cyst content, the peripheral side of the epiglottis was seen on the left-upper side of the shrunken cyst. Therefore, laryngoscopy was performed by an insertion of the left side of the mouth, and tracheal intubation was achieved by endotracheal tube which was advanced blindly under the epiglottis. A week later, due to cyst reoccurrence, the patient was undergone surgery again. No problem arose during the course of anesthesia, surgical intervention and the postoperative period, and the patient was discharged on the fifth postoperative day. We concluded that the view of the glottis or other laryngeal structures can be obtained by shrinking the vallecular cyst size. J Med Cases. 2014;5(3):160-162 doi: http://dx.doi.org/ 10.14740/ jmc1970e

Airway Management in an Adult Patient With a Large Vallecular Cyst

Vallecular cysts are rarely seen in adults and occur as a result of the tongue base mucus retention. In cases with laryngeal inlet obstruction due to a vallecular cyst, the airway management sometimes might be a challenge. We presented the airway management of an adult patient with difficult airway due to a large vallecular cyst. A 28-year-old male patient with a large vallecular cyst was scheduled for surgical excision of the cyst under general anesthesia. Despite the use of different laryngoscopic blades, no laryngeal structure was seen due to the cystic formation. After aspiration of approximately 20 mL cyst content, the peripheral side of the epiglottis was seen on the left-upper side of the shrunken cyst. Therefore, laryngoscopy was performed by an insertion of the left side of the mouth, and tracheal intubation was achieved by endotracheal tube which was advanced blindly under the epiglottis. A week later, due to cyst reoccurrence, the patient was undergone surgery again. No problem arose during the course of anesthesia, surgical intervention and the postoperative period, and the patient was discharged on the fifth postoperative day. We concluded that the view of the glottis or other laryngeal structures can be obtained by shrinking the vallecular cyst size. J Med Cases. 2014;5(3):160-162 doi: http://dx.doi.org/ 10.14740/ jmc1970e

Unforeseen Consequences of Therapy With Continuous-Flow Pumps

> For use almost can change the stamp of nature. > > — Hamlet , Act III, Scene IV Hamlet's statement may well be applied to the marked alteration in normal mammalian physiology introduced by the use of left ventricular assist devices (LVADs), particularly the nonpulsatile devices. This alteration of the “stamp of nature” has led to changes in the normal circulatory physiology not previously encountered in the field of medicine. Two unanticipated consequences of the clinical application of LVAD technology—acquired aortic valve insufficiency (AI) and acquired von Willebrand syndrome (VWS)—are reported in this issue of Circulation: Heart Failure . Articles see pp 668 and 675 The report by Cowger et al1 quantifies a single-center experience with acquired AI after implantation of both the pulsatile HeartMate XVE (HM-XVE) and the nonpulsatile HeartMate II (HM-II) LVAD (Thoratec Corporation, Pleasanton, Calif). These investigators used echocardiography to study 78 patients who received the HeartMate XVE (n=25) or HeartMate II (n=53) LVAD between 2004 and 2008. They performed 315 studies at set time intervals and graded AI and aortic valve opening according to classic echocardiographic methodology. Trends in the development of AI were assessed in the group as a whole and were then compared by device type. Because this was a single-center study, the numbers available for follow-up evaluation were limited (49 patients at 6 months, 29 patients at 12 months, 13 patients at 18 months, and 5 patients at 24 months). However, an increase in both the development and the severity of AI was noted during this period. The grade of moderate-to-severe AI was approximately 11% at 6 months, 26% at 12 months, and 51% at 18 months. Compared with patients with the HM-XVE device, those with the HM-II pump had an increased incidence and severity of AI; however, in no patient was the AI severe enough to require intervention. The authors …

Ileoanal Pouch Inlet Obstruction Following Cesarean Section

Ileoanal Pouch Inlet Obstruction Following Cesarean Section

The management of thoracic inlet syndrome associated with Hurler's syndrome: a novel surgical technique☆

A 21-year-old male developed significant swelling of his tongue after a respiratory arrest. The patient had a history of Hurler's syndrome. Magnetic resonance imaging (MRI) angiogram delineated that the swelling was due to compression of his internal jugular veins at the level of the first rib, resulting in thoracic inlet obstruction. The standard surgical treatment of thoracic inlet obstruction was not suitable in this patient's case due to his short thick neck and his characteristic Hurler's syndrome body habitus. Therefore, a novel surgical strategy was used to decompress his head and neck vessels. The manubrium was widened using an iliac crest bone graft, stabilised using internal fixation plates and reconstructed with a pectoral muscle flap.

Artificial neural network modelling of the thermal performance of a compact heat exchanger

This paper reports the use of artificial neural network models to simulate the thermal performance of a compact, fin-tube heat exchanger with air and water/ethylene glycol anti-freeze mixtures as the working fluids. The model predictions were compared with experimental data over a range of flow rates and inlet temperatures and with various ethylene glycol concentrations. In addition, the inlet air flow was distorted by obstructing part of the inlet ducting near the front face of the exchanger. The artificial neural networks were able to predict the overall rate of heat transfer in the exchanger with a high degree of accuracy and in this respect were found to be superior over conventional non-linear regression models in capturing the underlying non-linearity in the data. Moreover the detailed spatial variations in outlet air temperature were also adequately predicted. The results indicate that appropriately trained neural networks can simulate both the overall and “local” characteristics of the compact heat exchanger. In addition the paper demonstrates how an alternative type of neural network, the so-called Self-Organising-Map (SOM), can be employed for heat exchanger condition monitoring by identifying and classifying the deterioration in exchanger performance which, in this case, was associated with different levels of inlet obstruction.

Laboratory Performance Testing of Venous Cannulae During Inlet Obstruction

Venous cannulae undergo continuous improvements to achieve better and safer venous drainage. Several cannula tests have been reported, though cannula performance during inlet obstruction has never been a test criterion. In this study, five different cannulae for proximal venous drainage were tested in a mock circulation that enabled measurement of hydraulic conductance after inlet obstruction by vessel collapse. Values for hydraulic conductance ranged from 1.11 x 10(-2) L/min/mm Hg for a Thin-Flex Single Stage Venous Cannula with an open-end lighthouse tip to 1.55 x 10(-2) L/min/mm Hg for a DLP VAD Venous Cannula featuring a swirled tip profile, showing a difference that amounts to nearly 40% of the lowest conductance value. Excessive venous drainage results in potentially dangerous high-negative venous line pressures independent of cannula design. Cannulatip design featuring swirled and grooved tip structures increases drainage capacity and enhances cannula performance during inlet obstruction.

CT angiographic demonstration of hepatic collateral pathways due to superior vena cava obstruction in Behçet's Disease

Behçet disease (BD) is a chronic multisystemic inflammatory disorder, mainly characterized by recurrent oral and genital ulcers, skin lesions, and uveitis. Large vein thrombosis in BD is unusual; when present, it is most frequently seen in the inferior or superior vena cava (SVC). The authors describe an unusual hepatic pseudolesion caused by abnormal focal enhancement through collateral pathways to the liver in two BD patients with SVC occlusion on three-dimensional multi-detector computed tomography, using volume rendering and maximum intensity projection techniques. BD should be suspected in patients presenting a focal increased hepatic enhancement area with collaterals caused by occlusion of the SVC without evidence of a hypercoagulable state or malignant mediastinal or thoracic venous inlet obstruction.

Frzb modulates Wnt-9a-mediated β-catenin signaling during avian atrioventricular cardiac cushion development

Normal development of the cardiac atrioventricular (AV) endocardial cushions is essential for proper ventricular septation and morphogenesis of the mature mitral and tricuspid valves. In this study, we demonstrate spatially restricted expression of both Wnt-9a (formerly Wnt-14) and the secreted Wnt antagonist Frzb in AV endocardial cushions of the developing chicken heart. Wnt-9a expression is detected only in AV canal endocardial cells, while Frzb expression is detected in both endocardial and transformed mesenchymal cells of the developing AV cardiac cushions. We present evidence that Wnt-9a promotes cell proliferation in the AV canal and overexpression of Wnt-9a in ovo results in enlarged endocardial cushions and AV inlet obstruction. Wnt-9a stimulates β-catenin-responsive transcription in AV canal cells, duplicates the embryonic axis upon ventral injections in Xenopus embryos and appears to regulate cell proliferation by activating a Wnt/β-catenin signaling pathway. Additional functional studies reveal that Frzb inhibits Wnt-9a-mediated cell proliferation in cardiac cushions. Together, these data argue that Wnt-9a and Frzb regulate mesenchymal cell proliferation leading to proper AV canal cushion outgrowth and remodeling in the developing avian heart.

Classification of radial compressor faults using pattern-recognition techniques

An application of pattern-recognition techniques for the classification of faults in a radial compressor is presented. A number of mechanical alterations, simulating faults, are introduced in a test compressor. They include the insertion of an inlet obstruction, an obstruction in a diffuser passage, variation of impeller tip clearance and impeller fouling. Two kinds of measurements, namely sound emission and casing vibration, are examined. Three kinds of pattern-recognition techniques with increasing complexity are used in order to classify the examined faults correctly according to engine condition. The possibility of using each one of these techniques for diagnosing faults in a radial compressor is also examined. It is demonstrated that minor faults, which do not affect performance, can be identified using the proposed techniques.

Classification of Radial Compressor Faults Using Pattern Recognition Techniques

Abstract An application of pattern-recognition techniques for the classification of faults in a radial compressor is presented. A number of mechanical alterations, simulating faults, are introduced in a test compressor. They include the insertion of an inlet obstruction, an obstruction in a diffuser passage, variation of impeller tip clearance and impeller fouling. Two kinds of measurements, namely sound emission and casing vibration, are examined. Three kinds of pattern-recognition techniques with increasing complexity are used in order to classify the examined faults correctly according to engine condition. The possibility of using each one of these techniques for diagnosing faults in a radial compressor is also examined. It is demonstrated that minor faults, which do not affect performance, can be identified using the proposed techniques.

A review of open biopsy for mediastinal masses.

To review the recent experience with biopsied mediastinal lesions in children and to assess the impact of recent advances in imaging and surgical techniques on diagnosis. The clinical and radiological features of 55 patients who had mediastinal biopsies at The Royal Alexandra Hospital For Children (RAHC) over 15 years were reviewed. Fifty-five patients presented to RAHC between 1978 and 1993 with lesions of the mediastinum requiring biopsy of that site. Thirty-one of the 55 (56%) lesions were malignant. Neurogenic tumours were the most common (40%). In order of frequency the following lesions were found: neuroblastoma (15), teratoma (eight), non-Hodgkin's lymphoma (NHL; eight), enteric cyst/duplication (five), ganglioneuroma (five), bronchogenic cyst (three), ganglioneuroblastoma (two), lymphangioma (two), abscess (two), Hodgkin's lymphoma (HL; two), oesophageal granuloma (one), Langerhan's cell histiocytosis (one), congenital fibromatosis (one). Eighty-two per cent of neurogenic tumours were located in the posterior mediastinum, while 75% of teratomas and 100% lymphoid tumours were located anteriorly. Symptoms were generally unhelpful in establishing a specific diagnosis and in 27% of cases the lesions were discovered incidentally. Physical signs, such as thoracic inlet obstruction and neurological findings, were helpful clinically in localizing lesions within the mediastinum. Chest radiography enabled lesions to be subdivided within the mediastinum. This localization, in combination with the age at presentation, predicted the tissue diagnosis. Computerized tomography (CT) and magnetic resonance imaging (MRI) further defined the lesion and demonstrated involvement of adjacent structures. Histology, however, was essential to distinguish benign from malignant lesions. The clinical presentation of mediastinal masses is often non-specific or incidental. Despite recent advances in imaging technology and biopsy techniques, full histological examination is required to exclude malignancy.

Evaluation of hepatic perfusion disorders with double-phase spiral CT.

Double-phase (dual-phase) spiral computed tomography (CT) represents a technologic advance that allows two evaluations of hepatic blood flow during a single 19-29-second breath hold: once during the hepatic arterial phase (HAP) and again during the portal venous phase (PVP). Perfusion disorders of the hepatic parenchyma are more readily observed at double-phase spiral CT. The various hepatic perfusion disorders are related to (a) portal venous inflow obstruction, (b) hepatic venous outflow obstruction (e.g., Budd-Chiari syndrome, cardiac failure, mediastinal fibrosis), (c) mediastinal or thoracic venous inlet obstruction, (d) focal liver lesions, (e) inflammatory processes, (f) normal anatomic variants in the hepatic blood supply, (g) altered hemodynamics after the placement of a transjugular intrahepatic portosystemic shunt, and (h) uncertain causes. In general, the area of involvement appears hyperattenuating on HAP images and of normal or near-normal attenuation on PVP images. Familiarity with the spiral CT appearances of different types of perfusion disorders allows the radiologist to separate clinically insignificant flow phenomena from perfusion disorders caused by underlying parenchymal or vascular disease.

Beidseitige Riesenblähzysten bei Lymphangioleiomyomatose der Lunge als seltene Ursache einer Einflußstauung

We report on a 27-year-old female developing acute thoracic inlet obstruction by bilateral pulmonary cysts which arose from pulmonary lymphangioleiomyomatosis and increased with respiratory treatment. Bilateral synchronous bullectomy via median sternotomy was necessary to resolve the life-threatening condition. The most frequent differential diagnoses are tension pneumothorax and pericardial tamponade. Although this case of thoracic inlet obstruction was caused by a rare disease it may serve to recall the therapeutic problems encountered in bullous pulmonary lesions under tension, especially regarding acute volume expansion due to one-way valve mechanism during respiratory treatment or general anaesthesia.