Adding Dexmedetomidine or Clonidine to Spinal Anesthesia for Cesarean Delivery

Overview

This study will examine whether addition of dexmedetomidine or clonidine (two alpha-2 adrenergic agonists) will improve the comfort of patients during spinal anesthesia for cesarean delivery. When added to standard spinal anesthesia consisting of bupivacaine (a local anesthetic) and fentanyl and morphine (two opioids), these medications may decrease some of the pulling/tugging/pressure sensations that patients sometimes feel during cesarean delivery, may prolong the anesthetic time, and may decrease postoperative pain.

While spinal anesthesia almost always creates a reasonably comfortable operative/birth experience, a significant proportion of women do experience significance "pressure" or "pulling" and some do have sensations described as painful during the operation. This has received increased interest in both the medical and lay press in recent years. The main medication in a spinal anesthetic is the local anesthetic, usually bupivacaine, but a variety of adjuvants can and are used to improve the analgesia and decrease sensation (or increase the time period of effectiveness) of the anesthetic. Opioids (usually fentanyl or sufentanil for intraoperative benefits and morphine for postoperative analgesia) are very commonly added to spinal anesthetics for cesarean delivery in the United States. Somewhat less commonly, but increasingly, alpha-2 adrenergic agonists (clonidine or dexmedetomidine), which have sedative and analgesic properties (mostly analgesic when given into spinal fluid) are added in an attempt to improve the intraoperative experience and/or lengthen the time the block is effective. These adjuvants, although not approved specifically for this use in spinal anesthesia, have become more widely used in spinal anesthesia, including for cesarean delivery, and have been mentioned/recommended in recent statements by the American Society of Anesthesiologists for use when additional or improved analgesia may be needed or desired. The quality of the studies of intrathecal dexmedetomidine as part of spinal anesthesia for cesarean delivery is quite poor. This study will investigate whether clonidine or dexmedetomidine, when added to a spinal anesthetic containing bupivacaine/fentanyl/morphine, will improve intraoperative analgesia/anesthesia, decrease unwanted sensation, and assess what the other effects will be (prolongation of sensory and motor block, effects on blood pressure, other side effects).