State-of-the-Art Labor Analgesia

Patient-controlled Epidural Analgesia and Programmed Intermittent Epidural Bolusing Once a catheter has been placed into the epidural space, several options are available to maintain analgesia (Supplemental Digital Content 1, http://links.lww.com/ ASA/A347). One of the first methods to be used was intermittent bolusing on patient request. Once the effect of the initial dose of local anesthetic would begin to subside, contraction pain would return and the patient would request more medication, at which time the anesthesiologist would provide analgesia using another bolus dose of local anesthetic. The obvious disadvantage to this technique is the relatively large amount of manpower required. Other disadvantages include noncontinuous pain relief and an intermittent increase in side effects such as hypotension and motor blockade. The natural progression in management of labor analgesia was, then, to use infusions to maintain analgesia; however, early infusion pumps were relatively primitive and sometimes unreliable, and data were lacking to guide infusion rates. A large body of research was eventually published to help rectify the problem, and it was during this time that the next step in the evolution of maintenance of labor analgesia occurred: patient-controlled epidural analgesia (PCEA). By this time, copious experience had accumulated with the use of intravenous patient-controlled analgesia, and the same principles were then applied to PCEA. However, it was soon discovered that there are some important differences between opioid-based intravenous patient-controlled analgesia for acute postoperative pain and local anesthetic–based PCEA for labor analgesia. Perhaps most important, a basal infusion was found to be very effective