Effects on tramadol minimum alveolar concentration

Aim:Sevoflurane has a higher minimum alveolar concentration (MAC). This leads to an increase in the incidence of side effects. The use of opioid analgesics may lower the sevoflurane MAC to reduce possible cardiovascular side effects. We aimed to evaluate the effect of preoperative tramadol on sevoflurane minimum alveolar concentration (MAC) and hemodynamic parameters in a prospective, randomized, placebo controlled study. Materials and Methods: A total of 80 ASA I-II patients aged 18-65 years who were scheduled for operation were included to the study.Patients were divided into 4 groups. Group ET (n: 20): oral 50 mg tramadol, Group EP (n: 20): oral B complex vitamins, Group IT (n: 20): oral 50 mg tramadol, Group IP (n: 20): oral B complex vitamins. The medicines were made into cachets to look the same before the procedure. Standardized monitoring was achieved with preoperative electrocardiography (ECG), noninvasive blood pressure (NIBP), peripheral oxygen saturation (SpO2), and heart rate (HR). A baseline blood pressure value was determined by taking the average of the three NIBP values measured in two minutes. Results: Preoperative tramadol administration decreased sevoflurane MAC levels. The mean MAC values were 3.34 (2.20-4.00) in Group ET, 4.02 (3.20-4.60) in Group EP and statistically significantly lower than group EP in group ET (P <0.05). The mean MAC values were 2.61 (2.00-3.00) in Group IT and 2.90 (2.60-3.20) in Group IP. Statistically significant decrease was obtained Group IT than Group IP (p<0.05). There was a significant increasein HR, SBP and DBP in Group ET after the anesthesia induction and no significant difference after intubation. In Group IT, HR was significantly lower than Group IP (p>0.05), and no significant difference was found in SBP and DBP. Conclusion:Preoperative tramadol administration resulted in a significant decrease in sevoflurane MAC, while in the tramadol group in which the response to intubation was evaluated, there was an increase in HR, SBP and DBP compared with placebo. In the tramadol group in which response to incision was evaluated, there was a decrease in HR compared to placebo, but no significant difference was observed in SBP and DBP. Key words: Tramadol, Minimum alveolar concentration, Blood pressure, Heart rate, Sevoflurane