Background and Objective: Owing to the hemodynamic response to pneumoperitoneum, laparoscopic is not devoid of risk; adjuvants have been used to decrease the dose of volatile agents and their side effects and to blunt the hemodynamic response. This study was designed to compare the effect of dexmedetomidine and remifentanil on sevoflurane expired fraction concentration (EF sevo) in general anesthesia, monitored by BIS. Hemodynamic response, postoperative recovery profile, analgesic requirements and PONV were also recorded.
Patients and methods: General anesthesia induction with propofol 2.5 mg/kg rocuronium bromide 0.6 mgkg and sevoflurane 1-1.5 MAC. Tracheal intubation was performed and patients were mechanically ventilated. Patients were allocated to Groups D or R. Group D (≤ 40) was the dexmedetomidine group, they received dexmedetomidine diluted with 0.9% NaCl to a concentration of 4 ugmL in 50 mL (an initial loading dose of 0.7 ug/kg given for a 10 min period followed by 0.5 ug/kg/h). Group D (n=40) was the dexmedetomidine group, they received dexmedetomidine (Precedex, 200 ug per 2 mL; Abbott, USA) (an initial loading dose of 0.7 ug/kg given for a 10 min period followed by 0.4 ug/kg/h). Group R (n=40) was the remifentanil group and received an intravenous (i.v.) remifentanil (an initial loading dose of 0.7 ug/kg given for a 10 min period followed by 0.2 ug/kg/h). The infusion was stopped 15 min before the end of surgery. sevoflurane concentration adjusted to maintain BIS between 40 and 60. The parameters evaluated (BIS, SBP, DBP, MAP, HR, and EF sevo) were expressed as mean and standard deviation at 15 min before induction, during induction of anesthesia, 15 min later, during pneumperitonium, after release of insufflation and 15 min after release of insufflation.
Statistical analysis: Student’s t-test is a test of significance used for comparison of quantitative variables between two groups of normally distributed data, while Mann Whitney's test was used for comparison of quantitative variables between two groups of not normally distributed data. Chi-square test (χ2) was used to study association between qualitative variables. Whenever any of the expected cells were less than five, Fischer’s Exact test with Yates correction was used. P-value of <0.05 was considered statistically significant.
Results: No patients had marked hypotension MAP less than 60 mmHg or bradycardia HR less than 45 in both groups but there were significant decrease in HR and MAP between the two groups during induction, 15 min after induction, during pneumperitonium, aftert release of insufflation and 15 min after release of insufflation, extubation time, spontaneous eye movement, eye movement to verbal stimuli, spontaneous arm movement, purposeful movement and time of discharge to recovery room were significantly lower in group R than group D, However group R showed significantly higher EF sevo 15 min after induc, BSI during insufflation of CO2, EF sevo during insufflation of CO2, BSI after release. CO2, EF sevo after release of CO2, BSI before end of surgery and EF sevo before end of surgery than group D.
Conclusion: Both dexmedetomidine and remifentanil reduce the anesthetic requirement and depress the hemodynamic response during pneumoperitoneum with more significant decrease in EF sevo in the D group, however dexmedetomidine provides better postoperative analgesia and less incidence of PONV.