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Monitoring the evolution of the state of networks is an important issue to ensure that many applications provide the required quality of service. The first step in network-monitoring systems consists of capturing packets; that is, packets arrive at the system through a network interface card and are placed into system memory. Then, in this first stage, and usually in relation to the operating system, packets are treated and transferred from the capturing buffer to a higher-layer processing, for instance, to be analyzed in the next step of the system. In this work, we focus on the capturing stage. In particular, we focus on a Linux packet-capturing system. We model it as a single server queue. Taking into account that the server can be in charge not only of the capturing process but also of other tasks, we consider that the queue has vacations, i.e., there is some time when the capturing process cannot be carried out. We also assume that the queue has a finite buffer. We consider three different models and present a rigorous analysis of the derived Markov chain of each of the models. We provide standard performance metrics in all cases. We also evaluate the performance of these models in a real packet-capture probe. [ABSTRACT FROM AUTHOR]

The evolution of commodity hardware makes it possible to use this type of equipment to implement traffic monitoring systems. A preliminary empirical evaluation of a network traffic probe based on Linux indicates that the system performance has significant losses as the network rate increases. To assess this issue, we consider a model with two tandem queues and a moving server. In this system, we formulate a three-dimensional Markov Decision Process in continuous time. The goal of the proposed model is to determine the position of the server in each time slot so as to optimize the system performance which is measured in terms of throughput. We first formulate an equivalent discrete-time Markov Decision Process and we propose a numerical method to characterize the solution of our problem in a general setting. The solution we obtain in this problem has been tested for a wide range of scenarios and, in all the instances, we observe that the optimality is close to a threshold type policy. We also consider a real probe and we validate the good performance of threshold policies in real applications. [ABSTRACT FROM AUTHOR]

In this issue of I Pediatric Anesthesia i , Cruz-Beltran and colleagues report the results of a single-center retrospective study evaluating the association between HLA antibodies and prior exposure to allogeneic blood products in pediatric patients undergoing heart transplantation.1 Advancements made in perioperative management and immunosuppression have led to improved outcomes following heart transplant with a median survival of 16 years among all pediatric heart transplant recipients and up to 22 years in those transplanted during infancy. There are two distinct possibilities to explain those findings: patients with high pretransplant HLA antibody loads represent immune responsive patients who are at risk of developing more de novo post-transplant DSAs. In a recent matched cohort of patients who underwent kidney transplant, Yabu et al. reported that 10 of 50 (20%) transfused versus 6 of 155 (4%) nontransfused patients had >10 HLA antibodies increased >3000 MFI ( I p i = .0006); 6 of the 50 (12%) transfused patients had a > 30 antibodies ( I p i = .0007). [Extracted from the article]

Children with cyanotic congenital heart disease ( CCHD) have complex alterations in their whole blood composition and coagulation profile due to long-standing hypoxemia. Secondary erythrocytosis is an associated physiological response intended to increase circulating red blood cells and oxygen carrying capacity. However, this response is frequently offset by an increase in whole blood viscosity that paradoxically reduces blood flow and tissue perfusion. In addition, the accompanying reduction in plasma volume leads to significant deficiencies in multiple coagulation proteins including platelets, fibrinogen and other clotting factors. On the one hand, these patients may suffer from severe hyperviscosity and subclinical 'sludging' in the peripheral vasculature with an increased risk of thrombosis. On the other hand, they are at an increased risk for postoperative hemorrhage due to a complex derangement in their hemostatic profile. Anesthesiologists caring for children with CCHD and secondary erythrocytosis need to understand the pathophysiology of these alterations and be aware of available strategies that lessen the risk of bleeding and/or thrombosis. The aim of this review is to provide an updated analysis of the systemic effects of long-standing hypoxemia in children with primary congenital heart disease with a specific focus on secondary erythrocytosis and hemostasis. [ABSTRACT FROM AUTHOR]

There is a critical shortage of donor organs. According to the United Network for Organ Sharing (UNOS), 20% of organs are discarded after procurement. Many of these may be potentially salvageable. Brain death is particularly detrimental to cardiac function. The initial sympathetic storm can produce direct myocardial injury. The ensuing spinal shock reduces global oxygen delivery. There is a change to anaerobic metabolism due to global mitochondrial dysfunction. Diabetes insipidus worsens hypovolemia and thyroid deficiency impairs cardiac function. Inadequate replacement of blood loss from trauma and coagulopathy worsens anemia and oxygen delivery. In the mid-1990s, the Papworth Hospital group in the UK advocated early invasive hemodynamic monitoring and administration of a 'hormonal cocktail', consisting of triiodothyronine (T3), vasopressin, methyl-prednisolone and insulin. This has been widely accepted and is endorsed by UNOS. Ventricular function, volume status and adequacy of resuscitation should be guided by invasive monitoring and serial echocardiography. Dopamine or epinephrine is used for inotropic support. If hypotension persists, vasopressin should be added which may allow reduction of inotropes. Donor lung function and ventilation should be optimized. Recently, two large retrospective studies have shown that, with aggressive pharmacological and hormonal resuscitation, a significant increase in the number and quality of organs harvested can be achieved. [ABSTRACT FROM AUTHOR]

Summary We report a 3-year-old girl who presented with Scimitar syndrome and underwent hypothermic circulatory arrest for correction of anomalous pulmonary veins and an atrial septal defect. In this case the Bispectral Index (BIS) correlated significantly with the gradual onset of hypothermia and circulatory arrest. However, BIS remained low during the rewarming phase of cardiopulmonary bypass, in spite of adequate pump flows and stable haemodynamics. We postulate that this significant lag in BIS during the rewarming phase of deep hypothermic circulatory arrest may represent neuronal bewilderment or perhaps stunning, and differs from previous studies that show significant increase in BIS during rewarming from mild hypothermia. [ABSTRACT FROM AUTHOR]

The article presents the case of a cardiac arrest following induction of anesthesia due to unrecognized delayed dilated cardiomyopathy on a child with extensive burn injury. It offers information about the late impact on the heart of severely burned patients. It is of primary importance in the anesthetic management of patients with severe burn injuries to recognize cardiac compromise and maintain near baseline loading conditions, heart rhythm, stoke volume and systemic vascular resistance so as to maintain cardiac output at baseline.

The telecommunications sector has experienced significant changes over the past few years. The advent and rise of new applications and services, together with a competitive market, has led to a complex scenario in which quality of service plays a major role. Under this condition, novel QoS regulation and standardization initiatives are required. During the last few years new terms and concepts, such as quality of experience or QoS perceived, have been included in the updated and new QoS-related standards as to better integrate the user?s point of view, as opposed to only network performance parameters. The influence of the user?s satisfaction on the quality of business has also been given increased attention in the regulation and standardization bodies recently. The result is a loose collection of metrics and models that are not standardized and do not integrate all aspects of quality. Such integration is necessary to assure the successful development of this sector. This paper presents a new and integrated QoS model (QoXphere) that is spherical, adaptive, and multi-layered. [ABSTRACT FROM AUTHOR]

Clinically significant extrauterine twin‐twin transfusion syndrome in conjoined twins is rare and carries a high risk of perinatal mortality. The ensuing postnatal imbalance in circulation across connecting vessels results in hypovolemia in the donor and hypervolemia in the recipient. Data on management and treatment are sparse especially in the setting of a single ventricle congenital heart defect. We present a case of a pair of omphalopagus conjoined twins, one with a single ventricle physiology (Twin B), who developed twin‐twin transfusion syndrome shortly after birth. The resulting pathophysiology in the setting of a single ventricle congenital heart defect created added layers of complexity to their management and expedited surgical separation. Shunting from Twin B to Twin A—with an anatomically normal heart—resulted in mal‐perfusion and rapid deterioration jeopardizing the health of both twins. In the preoperative course, steps taken to medically optimize the twins prior to surgery and the anesthetic considerations are detailed in this report. [ABSTRACT FROM AUTHOR]

Intense vasospasm during hypertensive crisis as a cause for rhabdomyolysis has been described in ambulatory patients with pheochromocytoma. We report this phenomenon as an intraoperative complication in a patient during laparoscopic pheochromocytoma resection and discuss patient and procedure related risk factors. Unexplained intraoperative hyperkalemia following a severe hypertensive episode during surgery may be a first sign of rhabdomyolysis. Anesthesiologists should be aware of such a possibility. Intra- and postoperative serial electrolyte determinations and if suspected, timely screening for myoglobiuria, may aid in early detection and treatment of intraoperative rhabdomyolysis during pheochromocytoma resections. [Copyright &y& Elsevier]

Background: There are no established criteria to decide suitability for Fontan fenestration closure. Our institution has the following criteria: an unobstructed Fontan pathway with no significant decompressing venovenous collaterals, baseline Fontan pressure ≤15 mmHg, baseline cardiac index ≥2 L/min/m², and a decrease in cardiac index ≤20% with test occlusion of the fenestration. Objective: The objective of the study was to review midterm outcomes following device closure of Fontan fenestration using institutional criteria. Materials and Methods: A retrospective review was performed of patients who underwent catheterization with prior fenestrated Fontan procedure between May 2005 and January 2015. Patients were classified as those who underwent successful closure (A), had closure deferred due to failure to meet criteria (B), or were not referred for closure (C). Results: There were 42 patients in Group A, 10 in Group B, and 150 in Group C. The mean Fontan pressure increased from 13.1 ± 2.1 to 14.5 ± 2.1mmHg in Group A and 14.6 ± 1.5 to 15.7 ± 2.2 mmHg in Group B (P = not significant). With test occlusion, cardiac index fell by 18.12% ± 15.68% in Group A and 33.75% ± 14.98% in Group B (P = 0.019). At a median of 46 month follow up, oxygen saturation increased significantly from 85.15% ± 6.29% at baseline to 94.6% ± 4.43% (P < 0.001) in Group A but with no statistically significant difference in the rates of plastic bronchitis, protein losing enteropathy, stroke, or heart transplantation between the three groups. Conclusions: Using institutional criteria, transcatheter device closure of Fontan fenestration was followed by significant increase in oxygen saturations and no statistically significant difference in morbidity or mortality between closure and nonclosure groups. [ABSTRACT FROM AUTHOR]

Objectives To study the effect of two protamine-dosing strategies on activated clotting time ( ACT) and thromboelastography ( TEG). Background Protamine dosage based on neutralizing heparin present in the combined estimated blood volumes ( EBVs) of the patient and cardiopulmonary bypass ( CPB) pump may result in excess protamine and contributes toward a coagulopathy that can be detected by ACT and TEG in pediatric patients. Methods A total of 100 pediatric patients 1 month to ≤5 years of age undergoing CPB were included in this retrospective before/after design study. Combined- EBV group consisted of 50 consecutive patients whose protamine dose was calculated to neutralize heparin in the combined EBVs of the patient and the pump. Pt- EBV group consisted of the next 50 consecutive patients whose protamine dose was calculated to neutralize heparin in the patient's EBV. Results Baseline and postprotamine ACTs were similar between groups. Postprotamine heparin assay (Hepcon) showed the absence of residual heparin in both groups. Postprotamine kaolin-heparinase TEG showed that R was prolonged by 7.5 min in the Combined- EBV group compared with the Pt- EBV group (mean R of 20.17 vs 12.4 min, respectively, P < 0.001). Increasing doses of protamine were associated with a corresponding, but nonlinear increase in R. There was no significant difference in the changes for K, alpha, and MA between the groups. Conclusion Automated protamine titration with a protamine dosage based on Pt- EBV can adequately neutralize heparin as assessed by ACT while minimizing prolonging clot initiation time as measured by TEG. [ABSTRACT FROM AUTHOR]