The addition of droperidol or clonidine to epidural tramadol shortens onset time and increases duration of postoperative analgesia

Purpose: To compare tramadol alone and the combinations of either tramadol-clonidine or tramadol-droperidol with regard to analgesic and adverse effects. Methods: After Ethic's Committee approval and patient informed consent were obtained, epidural catheters were inserted preoperatively at the L3-4 interspace in 90 ASA physical status I-II adult patients undergoing lower abdominal surgery. Anesthesia was standardized. Patients were randomly assigned to one of three groups. Group I (T) patients received tramadol 75 mg, Group II (TD) patients received tramadol 75 mg plus droperidol 2.5 mg, and Group III (TC) patients received tramadol 75 mg plus clonidine 150 μg in a total volume of 10 mL administered as a single epidural injection in the postanesthesia care unit. The onset time of analgesia and duration of analgesia, visual analogue pain scores, sedation, nausea scores, vital signs and side effects were recorded. Results: Duration of analgesia was similar in both the TD and TC groups, and significantly longer than in the T group (P < 0.001). Group TC patients displayed a significant increase in sedation scores and decrease in blood pressure and heart rate when compared with other groups (P < 0.001). No adverse effects were observed in Group TD, while nausea scores were high in both the T and TC groups (P < 0.001). Pain score, respiration rate, and SpO2 values were similar in all study groups. Conclusion: We conclude that epidural tramadol in combination with droperidol or clonidine prolongs the duration of analgesia; however, droperidol appears to be a better alternative when adverse effects and antiemetic properties are taken into consideration

Hybrid seven-bar press mechanism: link optimization and kinetostatic analysis

An optimization study with kinetostatic analysis is performed on hybrid seven-bar press mechanism. This study is based on previous studies performed on planar hybrid seven-bar linkage. Dimensional synthesis is performed, and optimum link lengths for the mechanism are found. Optimization study is performed by using genetic algorithm (GA). Genetic Algorithm Toolbox is used with Optimization Toolbox in MATLAB®. The design variables and the constraints are used during design optimization. The objective function is determined and eight precision points are used. A seven-bar linkage system with two degrees of freedom is chosen as an example. Metal stamping operation with a dwell is taken as the case study. Having completed optimization, the kinetostatic analysis is performed. All forces on the links and the crank torques are calculated on the hybrid system with the optimized link lengths