THE ROLE OF CONTINUOUS BACKGROUND INFUSIONS IN PATIENT-CONTROLLED EPIDURAL ANALGESIA FOR LABOR AND DELIVERY

The use of a background infusion with intravenous patient-controlled a nalgesia (IV-PCA) increases drug consumption without any additional co ntribution to analgesia. There are no data on the potential advantage of a background infusion administered with patient-controlled epidural analgesia (PCEA) for labor and delivery. Sixty women were randomized to one of four groups and received either: (a) demand dose PCEA (deman d dose = 3 mL; lockout interval = 10 min); (b) continuous infusion plu s demand dose PCEA (two separate infusion rates: 3 mL/h and 6 mL/h); o r (c) a fixed-rate continuous epidural infusion (CEI) at 12 mL/h. Ah p atients received 0.125% bupivacaine with 2 mu g/mL, of fentanyl. The s tudy protocol was double-blind and placebo-controlled. Visual analog p ain scores, motor strength, and bilateral pinprick analgesia were asse ssed every half hour by a blinded observer. Pain scores, cephalad exte nt of sensory analgesia, and motor block were no different among the s tudy groups during the first and second stages of labor. Cumulative ho urly bupivacaine use was similar among all PCEA study groups. However, use of PCEA (in whatever mode) provided a 35% dose-sparing effect in comparison to CEI. The PCEA groups receiving no background infusion or a 3-mL/h background infusion had a greater need for physician-adminis tered supplemental bupivacaine during the first stage of labor. While not statistically significant, a trend toward increased need for suppl ementation was seen in these same patient groups over the entire cours e of labor and delivery. Patients with a continuous background infusio n of 6 mL/h plus demand dose PCEA obligatorily received 33% of their m aximum hourly demand dose as a background infusion. The need for physi cian-administered supplementation was minimal. Yet, pain scores, exten t of sensory analgesia, degree of motor block, and cumulative hourly b upivacaine use were equivalent to all other PCEA groups. Thus, adminis tration of a significant but modest proportion (i.e., 33%) of the maxi mum hourly demand dose as a continuous background infusion is appropri ate for PCEA during labor and delivery.