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Abstract Laparoscopy has now become the standard technique for cholecystectomy. However, the pneumoperitoneum (PNO) required for laparoscopy results in pathophysiologic changes (Joris et al. 1993). More particularly, changes in cardiovascular function occur during laparoscopy. These are characterized by an increase in arterial pressure and systemic and pulmonary vascular resistances (SVR and PVR) early after the beginning of intra-abdominal insufflation, with insignificant changes in heart rate (HR). A 10% to 30% decrease in cardiac output has also been reported in most studies (Joris et al.1993- Sharma et al. 1996). Today the theraputic objective for administration of α2-adrenoceptor agonists has shifted from reduction of high blood pressure to various other applications, including the management of myocardial ischaemia and withdrawal symptoms in drug addicts. The development of highly specific α2-adrenoceptor agonists with profound effects on vigilance and haemodynamics has created new interest for the use of α2-adrenoceptor agonists for use in anaesthesia and intensive care medicine. α2-Adrenoceptor agonists possess a variety of pharmacological properties that render them desirable as adjuncts in anaesthesia. Clonidine, an imidazoline, is the prototypal α2-adrenoceptor agonist. It has a relatively slow onset (0.5 h) and an elimination half-life of 9-12 h. The highly specific α2- adrenoceptor-agonist dexmedetomidine was approved in the USA at the end of 1999 for sedation and analgesia in the intensive care unit (ICU). This drug shows unique characteristics: patients are sedated but remain rousable and able to cooperate with the hospital staff when stimulated. Moreover, in ICU therapy with dexmedetomidine, there is no evidence of respiratory depression at clinical Summary 125 concentrations, and the heamodynamic changes are both moderate and predictable (Bhana N et al. 2000). The aim of this study is to compare the effect of two different infusion rates of dexmedetomidine on perioperative heamodynamic responses to painful stimulation, intubation, abdominal insufflation, anaesthetic requirement, postoperative analgesia and postoperative complication during abdominal laparoscopic procedure.This study was designed to include eighty patients of both sexes, aged 20-50 years, ASAI&II physical status, who are scheduled for elective abdominal laparoscopic cholecystectomy. All surgical procedures were of an expected duration of 30-75 minutes. All patients received the following drugs before the induction of anaesthesia: · 7.5 mg oral midazolam one hour before induction of anaesthesia · 0.5 mg IM atropine half an hour before induction of anaesthesia Patients were randomly assigned into one of four groups, as follows: Group I (control group) (n = 20): Patients in this group received placebo (normal saline), infused intravenously over 10 minutes. Group II (n = 20): Patients in this group received fentanyl 2μg/kg as a single dose followed by saline infusion for 10 minutes. Group III (n = 20): Patients in this group receive 0.5 μg/kg/h dexmedetomidine infusion 10 min before induction of anaesthesia and till the end of the operation. Group IV (n = 20): Patients in this group receive 1 μg/kg/h dexmedetomidine infusion 10 min before induction of anaesthesia and till the end of the operation. Ten minutes after administration of the study drug, the patients were given Tracrium 0.5 mg/kg IV. Anaesthesia was induced with sleeping dose of thiopental Na, after tracheal intubation with cuffed ETT a gas module for Summary 126 measurement of end-expiratory concentration of halothane and end-tidal carbon dioxide tension was applied. Data recorded as follow: · Heart rate ( HR ), blood pressure ( systole, diastole, mean), respiratory rate (RR), peripheral oxygen saturation ( Spo2) were recorded in the following times: - on arrival of the patients to the operating room - Every 2 minutes after study drug administration for 10 minutes. - Every 10 min in the recovery room for 2 hours · Heart rate ( HR ), blood pressure ( systole, diastole, mean),respiratory rate (RR), End tidal CO2 concentration (ETCO2), peripheral oxygen saturation ( Spo2), End tidal halothane concentration will be recorded at the following times: - immediately after intubation - every 2 min until 10 min after intubation then every 3 min for 15 min - Every 5 min during the rest of the operation. · Recovery was assessed by recording the time from extubation to spontaneous eye opening. · Post-operative analgesic requirement was assessed by recording the time to 1st request of post-operative analgesia. When comparing the four study groups together it was found that group 3 and 4 demonstrated statistically significant decrease in the heart rate, blood pressure and intraoperative halothane consumption compared with group 1 and 2 from intubation till the end of the surgery. Respiratory rate, SPO2, ETCO2 were comparable in all groups through the study period. There were insignificant Summary 127 differences between the study groups with respect to time from extubation till spontaneous eye opening, group 3 and 4 demonstrated statistically significant lower time to request of postoperative analgesia when compared with group 1 and 2. |