Labour epidural analgesia is highly effective but can be limited by slow onset and incomplete blockade. The administration of warmed, compared with room temperature, bupivacaine has resulted in more rapid-onset epidural anaesthesia. These authors hypothesised that the administration of bupivacaine with fentanyl at 37°C versus 20°C would result in improved initial and ongoing labour epidural analgesia.
Methods
The authors carried out a prospective, randomised, double-blinded study, in which 54 nulliparous, labouring women were randomised to receive epidural bupivacaine 0.125% with fentanyl 2 µg/mL (20 mL initial and 6 mL hourly boluses) at either 37°C or 20°C. Pain verbal rating scores (VRS), sensory level, oral temperature and side effects were assessed after epidural loading (time 0), at 5, 10, 15, 20, 30 and 60 minutes, and at hourly intervals. The primary outcome was the time to achieve initial satisfactory analgesia (VRS ?3). Secondary outcomes included ongoing quality of sensory blockade, body temperature and shivering.
Results
There were no differences between groups in patient demographics, initial pain scores, cervical dilatation, body temperature or mode of delivery. Epidural bupivacaine at 37°C resulted in shorter mean (±SD) analgesic onset time (9.2±4.7 versus 16.0±10.5 minutes, p=0.005) and improved analgesia for the first 15 minutes after initial bolus (p=0.001–0.03). Although patient temperature increased during the study (p<0.01), there were no differences between the groups (p=0.09). Six (24%) and 10 (40%) patients experienced shivering in the 37°C and 20°C groups, respectively (p=0.23).
Conclusions
The authors conclude that the administration of epidural 0.125% bupivacaine with fentanyl 2 µg/mL at 37°C versus 20°C resulted in more rapid onset and improved labour analgesia for the first 15 minutes. There was no evidence of improved ongoing labour analgesia or differences in side effects between groups.
Tags: bupivacaina, fentanyl