A two-level hybrid evolutionary algorithm for modeling one-dimensional dynamic systems by higher-order ODE models.

This paper presents a new algorithm for modeling one-dimensional (1-D) dynamic systems by higher-order ordinary differential equation (HODE) models instead of the ARMA models as used in traditional time series analysis. A two-level hybrid evolutionary modeling algorithm (THEMA) is used to approach the modeling problem of HODE's for dynamic systems. The main idea of this modeling algorithm is to embed a genetic algorithm (GA) into genetic programming (GP), where GP is employed to optimize the structure of a model (the upper level), while a GA is employed to optimize the parameters of the model (the lower level). In the GA, we use a novel crossover operator based on a nonconvex linear combination of multiple parents which works efficiently and quickly in parameter optimization tasks. Two practical examples of time series are used to demonstrate the THEMA's effectiveness and advantages.

Thoracic epidural anesthesia for laparoscopic cholecystectomy using either bupivacaine or a mixture of bupivacaine and clonidine: A comparative clinical study.

INTRODUCTION: Traditionally laparoscopic cholecystectomy is done under general anesthesia. But recently there is a growing interest to get it conducted under central neuraxial blockade. We conducted a clinical study comprising bupivacaine alone or a combination of bupivacaine and clonidine (2 µg/kg) in thoracic epidural anesthesia for laparoscopic cholecystectomy (LC). The aim was to attenuate the undesirable hemodynamic changes due to pneumoperitoneum (PNO) and achieve a better qualitative blockade. PATIENTS AND METHODS: After taking approval from Institutional Ethical Committee, 50 adult patients of ASA grade I and II were divided into two groups; group A where bupivacaine was given with 2 µg/kg of clonidine (Cloneon, Neon) and in group B bupivacaine (Anawin, Neon) was given with 1 ml of saline as placebo. Thoracic epidural was given at the T9-T10 or T10-T11 interspace to obtain a block of T4-L2 dermatome. Hemodynamic parameters like heart rate (HR), noninvasive blood pressure (NIBP), respiratory rate (RR), electrocardiogram (ECG), oxygen saturation (SpO2) and arterial pressure of carbon dioxide (PaCO2) were monitored and readings were recorded before and 10 minutes (min.) after the blockade and then at 5 min, 15 min and 30 min after PNO and 15 min after exsufflation. RESULTS: All the parameters of the patients in group A remained stable but the patients of group B showed an increase in mean arterial pressure (MAP) and HR at 5, 15 and 30 min after PNO and 15 min after exsufflation as compared to Group A. PaCO2, SpO2 and RR values in both the groups were comparable. In group A, two patients complained of shoulder pain while in group B12 patients complained of shoulder pain. CONCLUSION: Thoracic epidural anesthesia for LC is a satisfactory alternative technique in selected cases. Addition of clonidine (2 µg/kg) to bupivacaine produces better qualitative anesthetic conditions. It prevents hemodynamic perturbations produced by pneumoperitoneum and also decreases the incidence of shoulder pain. Thus we strongly advocate the incorporation of clonidine as an adjuvant in thoracic epidural anesthesia for LC.

Midline Submental Orotracheal Intubation in Maxillofacial Injuries: A Substitute to Tracheostomy Where Postoperative Mechanical Ventilation is not Required.

BACKGROUND: Maxillofacial fractures present unique airway problems to the anaesthesiologist. Nasotracheal intubation is contraindicated due to associated Lefort I, II or III fractures. The requirement for intraoperative maxillomandibular fixation (MMF) to re-establish dental occlusion in such cases precludes orotracheal intubation. Tracheostomy has a high complication rate and in many patients, an alternative to the oral airway is not required beyond the perioperative period. Hernandez1 in 1986 first described "The submental route for endotracheal intubation". Later some workers faced difficult tube passage, bleeding, and sublingual gland involvement with this approach. They modified this to strict midline submental intubation and there were no operative or postoperative complications in their cases.67&8. Therefore we used mid line approach for submental orotracheal intubation in this study to demonstrate its feasibility and reliability and that it can be used as an excellent substitute to short term tracheostomy. PATIENTS #ENTITYSTARTX00026; METHODS: We used midline submental intubation in 25 cases selected out of 310 consecutively treated patients with maxillofacial trauma over a 3 year period. After induction orotracheal intubation was done with spiral re-inforced tube. A 1.5-2.0 cm skin incision was made in the submental region in the midline 2.0 cm behind the symphysis and endotracheal tube was taken out through this incision in all the cases. At the end of the surgery the procedure was reversed, the submental wound was stitched; all the patients could be extubated & none of them required post-operative mechanical ventilation. CONCLUSION: There were no significant operative or postoperative complications. Postoperative submental scarring was acceptable([6]). We conclude that midline submental intubation is a simple and useful technique with low morbidity. It can be chosen in selected cases of maxillofacial trauma and is an excellent substitute to tracheostomy where postoperative mechanical ventilation is not required.