Estimated blood loss (EBL), non-autologous transfusion rates, and change of hemoglobin (Hb) levels between two groups were compared to investigate the effect of adding meperidine to lidocaine on blood loss. The EBL in the operating room and recovery unit, and non autologous blood transfusion was recorded. Motor block (MB) was assessed BGJ398 according to the Bromage scale,12 1: unable to move feet, 2: able to move feet only, 3: just able to move knees, and 4: full flexion of knees and feet. Complete motor block was defined

as a Bromage score of three. Pain was assessed in operating room, recovery room, and the ward for 12 hours using the 10-score visual Inhibitors,research,lifescience,medical analog scale (VAS). If a patient complained of a pain score over three, (1.5 µg/kg) IV fentanyl would be prescribed,

and in the event of failed spinal block, general anesthesia would be performed. Midazolam was given intravenously in 0.5 mg increments as was indicated for anxiolysis. All patients were asked about the presence Inhibitors,research,lifescience,medical of headache, backache, paraesthesia, pain in thighs, buttocks, or leg, etc during the first and second Inhibitors,research,lifescience,medical post-operative days. Assuming that the incidence of hypotension by meperidine to be 8% percent and that of lidocaine to be 33%, it was predicted that the study would require 38 patients in each group to provide a power of 80% to detect a 35% differences in the incidence of hypotension. The data obtained were analyzed using the Statistical Package for Social Sciences software, version 11.0 (SPSS Inc, Chicago, IL, USA). Descriptive statistics were computed for the characteristics of the patients, and preoperative and postoperative hemodynamic changes. Repeated measure test ANOVA Student’s t test, and paired t test were used for between and within-group comaprisons. Inhibitors,research,lifescience,medical Bonferroni procedure to P value to avoid committing type 1 error after repeated measure ANOVA Chi square and Fisher exact tests were used to analyze nominal variables. A P value

of <0.05 was considered statistically significant. Results Thirty eight patients in the experimental group and 39 patients Inhibitors,research,lifescience,medical in the control group finished the study. The two groups were not statistically different with regards to the age, weight, or duration of operation (P>0.05). Baseline hemodynamic data and pre-operative hemoglobin were enough not significantly different between the two groups (table 1). The hemodynamic effects of subarachnoid block were studied among all patients in the two study groups. Heart rate in the patients receiving intrathecal meperidine was not significantly (P=0.08) different from the baseline value (table 2). The systolic and diastolic blood pressures in the two groups were significantly (P<0.0001) different from the baseline values after the induction of anesthesia. Moreover, the percent of patients, who experienced over 30% decrease in mean blood pressure, was significantly (P<0.0001) higher in the control group (56.4%) compared to that of the experiment group (7.