Postoperative analgesia requirement was less in the meperidine group compared to that in the C59 wnt in vivo lidocaine group. They concluded that intrathecal 5% meperidine in a dose of 1 mg/kg was superior

to 5% heavy lidocaine because of the prolonged postoperative analgesia. Some findings of this study confirm our results, but some others do not. Norris et al.22 compared the anesthetic potency, duration, and side effects of subarachnoid meperidine and lidocaine in twenty healthy unpremedicated postpartum women, who were candidates for postpartum tubal ligation. They found that sensory or motor block developed slightly faster in the lidocaine group. Patients who received meperidine experienced Inhibitors,research,lifescience,medical more pruritus. Patients receiving lidocaine had more postoperative pain, and required supplemental analgesia. No patient’s oxygen saturation fell below 95%. Patients expressed equal satisfaction with both agents. The study concluded that subarachnoid meperidine had no advantage Inhibitors,research,lifescience,medical compared to lidocaine for postpartum tubal ligation except for meperidine providing longer postoperative analgesia. The only investigators, who studied the hemodynamic effects of intrathecal meperidine, were Cozian

et al.23 They Inhibitors,research,lifescience,medical exercised some invasive monitoring on eight patients, and measured radial arterial pressures and cardiac output. They found statistically insignificant decreases in MAP, CVP and left atrial pressure with no change in CI and HR. Level of sensory block in that study was the same as that in ours (T8). Inhibitors,research,lifescience,medical The findings of Cozian et al.23 are similar to our findings in operative room, and suggest that intrathecal meperidine causes a sympathetic block similar to intrathecal local anesthetics with no significant effect on BP. In the present study no patient showed respiratory depression, which might be due to the use of a low dose of meperidine (0.4 mg/kg). However, the previous study by Nguyen et al.19 showed that respiratory depression

could occur with doses as low as 0.5 mg/kg. Maurette et al.24 investigated the mechanisms leading to respiratory depression after lumbar administration of opioids. Inhibitors,research,lifescience,medical They studied plasma and ventricular cerebrospinal fluid (CSF) pharmacokinetics of intrathecal meperidine (1 mg/kg) in five head-injured patients undergoing surgery for lower limb fracture. Meperidine was detected both in the plasma (arterial catheter) and in the Phosphoprotein phosphatase ventricular CSF (intracranial catheter) soon after intrathecal administration. The study concluded that the putative risk of respiratory depression appears to be mainly related to the absorption into the systemic circulation and redistribution back into the CSF. The post-operative hypertension usually begins within 30 min from the end of operation and lasted about two hours. The principal factors possibly contributing to the pressure elevations are pain, hypercarbia and emergence excitement.