Epidural anesthesia and postoperative analgesia with ropivacaine and fentanyl in off-pump coronary artery bypass grafting: a randomized, controlled study

<p>Abstract</p> <p>Background</p> <p>Our aim was to assess the efficacy of thoracic epidural anesthesia (EA) followed by postoperative epidural infusion (EI) and patient-controlled epidural analgesia (PCEA) with ropivacaine/fentanyl in off-pump coronary artery bypass grafting (OPCAB).</p> <p>Methods</p> <p>In a prospective study, 93 patients were scheduled for OPCAB under propofol/fentanyl anesthesia and randomized to three postoperative analgesia regimens aiming at a visual analog scale (VAS) score < 30 mm at rest. The control group (n = 31) received intravenous fentanyl 10 μg/ml postoperatively 3-8 mL/h. After placement of an epidural catheter at the level of Th₂-Th₄before OPCAB, a thoracic EI group (n = 31) received EA intraoperatively with ropivacaine 0.75% 1 mg/kg and fentanyl 1 μg/kg followed by continuous EI of ropivacaine 0.2% 3-8 mL/h and fentanyl 2 μg/mL postoperatively. The PCEA group (n = 31), in addition to EA and EI, received PCEA (ropivacaine/fentanyl bolus 1 mL, lock-out interval 12 min) postoperatively. Hemodynamics and blood gases were measured throughout 24 h after OPCAB.</p> <p>Results</p> <p>During OPCAB, EA decreased arterial pressure transiently, counteracted changes in global ejection fraction and accumulation of extravascular lung water, and reduced the consumption of propofol by 15%, fentanyl by 50% and nitroglycerin by a 7-fold, but increased the requirements in colloids and vasopressors by 2- and 3-fold, respectively (<it>P </it>< 0.05). After OPCAB, PCEA increased PaO₂/FiO₂at 18 h and decreased the duration of mechanical ventilation by 32% compared with the control group (<it>P </it>< 0.05).</p> <p>Conclusions</p> <p>In OPCAB, EA with ropivacaine/fentanyl decreases arterial pressure transiently, optimizes myocardial performance and influences the perioperative fluid and vasoactive therapy. Postoperative EI combined with PCEA improves lung function and reduces time to extubation.</p> <p>Trial Registration</p> <p><a href="http://www.clinicaltrials.gov/ct2/show/NCT01384175">NCT01384175</a></p

BIM competencies for delivering waste-efficient building projects in a circular economy

Competency measures are increasingly becoming effective ways for construction organizations to measure their ability to deliver waste-efficient projects. Despite the ongoing efforts in achieving the goals of the circular economy through BIM adoption, there is still a paucity of studies on building information modeling (BIM) competencies for delivering waste-efficient building projects. This paper, therefore, aims to identify and investigate critical BIM competencies for delivering waste-efficient building projects in a circular economy. The study adopts a pluralistic approach, using a combination of the review of extant literature, focus group discussions and questionnaire survey. Analysis of the focus group discussion along with the result of the literature review revealed forty-three preliminary BIM competencies, which were subjected to rigorous statistical analyses. Four broad categories of BIM competencies for delivering waste-efficient building projects emerged from the analyses. These are project management-related, construction-related, procurement-related, and design-related BIM competencies. Construction firms could use the BIM competencies identified in this study to enhance the delivery of waste-efficient building projects as well as assess their BIM competency requirements at an individual and organizational level

Centre for Quantifiable Quality of

Abstract — Fountain codes provide an efficient way to transfer information over erasure channels. We give an exact performance analysis of a specific type of fountain codes, called LT codes, when the message length N is small. Two different approaches are developed. In a Markov chain approach the state space explosion, even with reduction based on permutation isomorphism, limits the analysis to very short messages, N ≤ 4. An alternative combinatorial method allows recursive calculation of the probability of decoding after N received packets. The recursion can be solved symbolically for values of N ≤ 10 and numerically up to N ≈ 30. Examples of optimization results give insight into the nature of the problem. In particular, we argue that a few conditions are sufficient to define an almost optimal LT encoding. I

A model for TCP congestion control capturing the

We consider a simplified model for the rate control of TCP sources. In particular, we assume idealized negative feedbacks upon reaching a certain total sending rate, i.e., at the moment when the total sending rate attains a given capacity limit c one of the TCP sources is given a negative feedback and the source reduces its sending rate in a multiplicative manner. Thus, the model takes into account the interactions between different flows appropriately at the microscopic level instead of assuming independence. For this model we are able to derive steady state equations and solve them. Furthermore, we are able to compute several important performance measures such as the mean and the variance of the total sending rate. Moreover, we are able to characterize the packet loss process at the bottleneck link and, in particular, the correlations therein