Причины развития послеоперационного энтероколита при болезни Гиршпрунга у пациентов детского возраста

ГИРШСПРУНГА БОЛЕЗНЬ /ХИРАГАНГЛИОЗ ТОЛСТОЙ КИШКИ ВРОЖДЕННЫЙ /ХИРМЕГАКОЛОН ВРОЖДЕННЫЙ /ХИРТОЛСТАЯ КИШКА /ХИРКИШЕЧНИК ТОЛСТЫЙ /ХИРПОСЛЕОПЕРАЦИОННЫЕ ОСЛОЖНЕНИЯЭНТЕРОКОЛИТТРАНСАНАЛЬНОЕ ЭНДОРЕКТАЛЬНОЕ НИЗВЕДЕНИЕДЕТИТотальная мезоректумэктомия является фактором риска развития и формирования патологических пресакральных синусов. В результате резекции прямой кишки с тотальной мезоректумэктомией в тазу образуется объемная полость, ограниченная костными структурами. При накоплении в ней жидкости, крови увеличивается риск инфицирования и образования пресакральных абсцессов. Если патологическая полость не заживает на протяжении 12 месяцев, такой синус считают хроническим. Хронический пресакральный синус образуется у 5-9,5% пациентов, которым проводилась тотальная мезоректумэктомия. Основными факторами развития являются неоадъювантная химиолучевая терапия, высокая интраоперационная кровопотеря, опухоли больших размеров. Диагностика заключается в проведении следующих инструментальных методов: ректоскопия, проктография, магнитно-резонансная томография органов малого таза. Основным методом лечения при небольших синусах является использование фибринового клея и системы EndoVac. Фибриновый клей механически закрывает дефект, стимулирует пролиферацию фибробластов и служит матриксом для синтеза коллагена, процессов заживления раны. Чаще всего фибриновый клей применяется как завершающий этап терапии системой EndoVac, при котором губка, соответствующая размерам дефекта, устанавливается в полость абсцесса и меняется через каждые 48-72 часа. Степень эффективности 66-100%. В случаях больших размеров синусов, дренирующихся через небольшой дефект в анастомозе, или неэффективности системы EndoVac, для создания адекватного дренирования целесообразно применение методики эндоскопической марсупиализации. Данная методика позволяет сохранить колоректальный анастомоз. Пациентам с симптоматическим пресакральным синусом, у которых реверсия стомы невозможна, рекомендуется выполнять чрессфинктерную проктэктомию с тампонадой полости большим сальником.Total mesorectumectomy is a risk factor of development and formulation of pathological presacral sinuses. In the result of the rectum resection with total mesorectumectomy, the volumetric cavity is formed in the pelvisbounded by thebone structures. In case of accumulation of the liquid and blood in it, the risk of infection and the formation of presacral abscesses increases. If the pathological cavity does not heal during 12 months, such sinus is considered to be chronic. The chronic presacral sinus is formed in 5-9.5% of patients, those who underwent total mesorectumectomy. The main causes of development are neoadjuvantchemotherapy, high intraoperative bleeding, tumors of large size. The diagnostics includes the following instrumental methods: rectoscopy, proctography, magnetic resonance imaging of the pelvic organs. The basic methods of treatment in small sinuses are the application of fibrin glue and the EndoVac system. Fibringluecloses defects mechanically, stimulates proliferation of fibroblasts and provides matrix for the synthesis of collagen and for the processes of the wound healing. Fibrin glue is most often used as the final stage of the EndoVac system therapy, when a sponge, corresponding to the defect sizes, is placed in the abscess cavity, and is replaced every 48-72 hours. Treatment effectiveness is 66-100%. In the case of a large sinus, drained through a small defect in anastomosis or inefficiency of the EndoVac system, the method of endoscopic marsupialization is appropriate to be used. The given method allows saving the colorectal anastomosis. In patients with symptomatic presacral sinus in whom stoma reversionis impossible, transversal proctectomy with the cavity tamponade by greater omentum is advisable

Link adaptation for energy-efficient uplink coordinated multi-point receptions

We investigate link adaptation methods for energy-efficient uplink coordinated multi-point receptions. A system model for practical cellular networks is introduced, in which only a subset of base stations participates in cooperative link adaptation and cooperative decoding for uplink transmissions. To cope with channel-state-information (CSI) mismatch incurred from the system model, link adaptation controllers implementing rate back-off from the maximum achievable rate calculated with the mismatched CSI is introduced. From analytical and simulation results, it is concluded that under a certain condition, the rate back-off does not help to improve energy efficiency, where, for example, the condition holds when the CSI errors are modeled as additive Gaussian random variables. Furthermore, energy efficiency of multi-user spatial-division-multiple-access uplink transmissions is studied in isolated cooperative cellular networks. In this scenario, an analytical expression for the optimal link adaptation achieving maximum energy efficiency is obtained

Link adaptation for energy-efficient uplink coordinated multi-point receptions

We investigate link adaptation methods for energy-efficient uplink coordinated multi-point receptions. A system model for practical cellular networks is introduced, in which only a subset of base stations participates in cooperative link adaptation and cooperative decoding for uplink transmissions. To cope with channel-state-information (CSI) mismatch incurred from the system model, link adaptation controllers implementing rate back-off from the maximum achievable rate calculated with the mismatched CSI is introduced. From analytical and simulation results, it is concluded that under a certain condition, the rate back-off does not help to improve energy efficiency, where, for example, the condition holds when the CSI errors are modeled as additive Gaussian random variables. Furthermore, energy efficiency of multi-user spatial-division-multiple-access uplink transmissions is studied in isolated cooperative cellular networks. In this scenario, an analytical expression for the optimal link adaptation achieving maximum energy efficiency is obtained

Cross-layer optimization for spectral and energy efficiency

The future success of communication networks hinges on the ability to overcome the mismatch between requested quality of service (QoS) and limited network resources. Spectrum is a natural resource that cannot be replenished and therefore must be used efficiently. On the other hand, energy efficiency (EE) is also becoming increasingly important as battery technology has not kept up with the growing requirements stemming from ubiquitous multimedia applications. The qualities of wireless channels vary with both time and user. We use channel state information (CSI) to dynamically assign wireless resources to users to improve spectral and energy efficiency. We first investigate a series of general treatments of exploiting CSI in a distributed way to control the medium access to maximize spectral efficiency for networks with arbitrary topologies and traffic distributions. As the first step, we propose decentralized optimization for multichannel random access (DOMRA), which uses local CSI and two-hop static neighborhood information to achieve performance comparable with the global optimal channel-aware Aloha. The generic framework developed in DOMRA proved to be very useful in improving cellular networks as well. We develop cochannel interference avoidance (CIA) medium access control (MAC), which is optimized by DOMRA, to mitigate the downlink severe cochannel interference that is usually experienced by cell-edge users. Aloha-based schemes have low channel utilization efficiency because of the collision of entire data frames. We further develop channel-aware distributed MAC (CAD-MAC), which avoids collision through signaling negotiation ahead of data transmission. CAD-MAC completely resolves the contention of networks with arbitrary topologies, achieves throughput close to centralized schedulers, and is robust to any channel uncertainty. Then we address energy-efficient wireless communications while emphasizing orthogonal frequency multiple access (OFDMA) systems. We first discover the global optimal energy-efficient link adaptation in frequency-selective channels using the strict quasiconcavity of energy efficiency functions. This link adaptation optimally balances the power consumption of electronic circuits and that of data transmission on each subchannel. The global optimal energy-efficient transmission can be obtained using iterative operations, which may be complex to be implemented in a practical system. Besides, running iterative algorithms consumes additional energy. Hence, we further develop a closed-form link adaptation scheme, which performs close to the global optimum. Besides, since subchannel allocation in OFDMA systems determines the energy efficiency of all users, we develop closed-form resource allocation approaches that achieve near-optimal performance too. In an interference-free environment, a tradeoff between EE and spectral efficiency (SE) exists, as increasing transmit power always improves SE but not necessarily EE. We continue the investigation in interference-limited scenarios and show that since increased transmit power also brings higher interference to the network, SE is not necessarily higher and the tradeoff is improved. Especially, in interference-dominated regimes, e.g., local area networks, both spectral- and energy-efficient communications desire optimized time-division protocols and the proposed DOMRA, CIA-MAC, and CAD-MAC can be used to improve both spectral and energy efficiency.Ph.D.Committee Chair: Li, Geoffrey Ye; Committee Member: Ma, Xiaoli; Committee Member: Stuber, Gordon; Committee Member: Wardi, Yorai; Committee Member: Yu, Xingxin

On Optimal Energy-Efficient Multi-User MIMO

Energy efficiency is becoming increasingly importantfor mobile devices because battery technology has notkept up with the growing demand of ubiquitous multimediacommunications. Since multi-user multiple-input multiple-output(MU-MIMO) is a key technology in next-generation wirelesscommunications, this paper addresses optimal energy-efficientdesign for MU-MIMO. The energy efficiency is measured by aclassic metric, “throughput per Joule”, while both RF transmitpower and device electronic circuit power are considered. Wedefine the energy efficiency (EE) capacity for MU-MIMO andstudy the power allocation that achieves this capacity. We showthat user antennas should be used only when the correspondingsubchannels are sufficiently good and using them improves theoverall network EE. Based on theoretical analysis, we further developlow-complexity yet globally optimal energy-efficient powerallocation algorithms that converge to the optimum exponentially.Finally comprehensive simulation results are provided todemonstrate the significant gain in network energy efficiency.QC 20130114</p

Energy-Efficient Uplink Multi-User MIMO with Dynamic Antenna Management

Energy efficiency is important for mobile devices because battery technology development has not kept up with the growing demand of ubiquitous broadband communications. This paper addresses optimal energy-efficient design for uplink (UL) MU-MIMO in a single cell environment. We assume mobile devices have dynamic antenna management capability and can turn off circuit operations when some antennas are not used to save power. We show that some antennas should not be used even when their channel states are good because turning them on consumes too much circuit power. This indicates a single antenna system could perform better than a multi-antenna system in terms of energy efficiency. Based on theoretical analysis, we further develop low-complexity yet globally optimal algorithms that converge to the optimum exponentially.QC 201302156005

Energy-Efficient Uplink Multi-User MIMO

This paper addresses optimal energy-efficient design for uplink (UL) MU-MIMO in a single cell environment. The energy efficiency is measured by throughput per Joule, while both RF transmission power and device electronic circuit power are considered. We define the energy efficiency (EE) capacity for UL MU-MIMO and study the power allocation that achieves this capacity. First we assume all users consume a fixed amount of circuit power and show that user antennas should be used only when the corresponding spatial channels are sufficiently good and using them improves the overall network EE. Mobile devices may have improved circuit management capability and turn off circuit operations when some antennas are not used to reduce circuit power consumption. Therefore we further study energy-efficient UL MU-MIMO with improved circuit management and show that some antennas should not be used even when their channel states are good because turning them on consumes too much circuit power. Based on theoretical analysis, we further develop low-complexity yet globally optimal energy-efficient power allocation algorithms that converge to the optimum exponentially. Simulation results are provided to demonstrate the significant gain in network energy efficiency.QC 20130723Low-energy wireless system