Postoperative pain management in day surgery

the very rapid clearance ofsufentanil &om CSF-mce that ofpethiidine and 2-10 times that of morphne. In 1991, Handsomer stated that 75 pg of sufentanil should be a maximal bolus dose given epidurally; the CSF concentration was in the range seen after 15 pg given intrathecally. In 1994, Van Decar determined a dose-response curve for intrathecal sufentanil dunng labour. This study suggested that the ED,, for intrathecal sufentanil is 2.5 pg and that the ED,, between 7.5 and 10 pg. The duration ofanalgesia increased as the dose of sufentanil increased. Another study showed that there was no relationshp between the injectate volume of intrathecal sufentanil and the durauon or quality of analgesia. The addition of 0.2 mg adrenaline to intrathecal sufentanil did not significantly prolong labour analgesia. Both early and late respiratory depression have been seen with spinal opioid administration. Early respiratory depression is thought to be secondary to the effect of systemically absorbed drug. The respiratory depression observed with lipid4oluble opioids is more Lkely to be associated with high serum levels, that is, the same mechanism that is associated with systemic routes of administration. Respiratory depression with spinally administered opioids appears to be dose related. Verborgh found that the respiratory rate was significantly decreased from 15 min to 1 h after 75 pg of epidural sufentanil; however, the addition of adrenaline significantly prolonged the duration of analgesia and decreased hypercapnia and caused a reduction in respiratory rate. A case report of delayed respiratory arrest after the use of combined spinal and epidural anesthesia suggested a risk of epidurally administered opioid. Leighton found that epidural bupivacaine anaesthetised more dermatomes afier intrathecal sufentanil than when administered alone. The appropriate dose of epidural local anaesthetic must be individualised when intrathecal opioids are used!