The association of low-dose of bupivacaine plus fentanyl was more effective and safe than medium-dose of bupivacaine in epidural analgesia during labour

Inmaculada Bellido1, Gonzalo J Perez-Villarejo2, Mariano J Fernandez-Baena2, Aurelio Gomez-Luque3
1D. Pharmacology and Clinical Therapeutic. Medicine School. University of Malaga, Malaga, Spain, 2S. Anesthesiology, Carlos Haya Universitary Hospital, Malaga, Spain, 3S. Anesthesiology, Virgen de la Victoria Universitary Hospital, Malaga, Spain

Spinal block for labour analgesia with high-dose of local anaesthetic such as bupivacaine has been associated with headache, hypotension, motor block, neurological sequels (bilateral pain in the buttocks or thighs, new-onset back pain, paraesthesia in the feet…), and excessive somnolence in the mother. It has also been associated with somnolence and heart rate abnormalities in the foetus and the neonate (Sah et al., 2007). As this analgesic technique is nowadays a routine use in the labour ward, it is necessary to improve it using the most effective and safe drugs and drug dose (Bolukbasi et al., 2005; Goring-Morris and Russell, 2005). Our aim was to compare the efficacy and safety of epidural analgesia with low-dose of bupivacaine plus fentanyl (B+F) vs. medium-dose of bupivacaine (B) during labour.

In a randomized, double-blinded study 117 ASA I-II parturients (aged 29.8±0.5 years, primiparous with mono-foetal gestation, at 37-42 weeks’ gestation, cervical dilatation <4 cm and rhythmic labour contractions were randomly allocated to receive either epidural analgesia with 12 mL/h of 0.25% bupivacaine (group B, n=54) or combined 0.125% bupivacaine with 5 μg fentanyl (group B+F, n=63). In both groups, the original analgesia was followed by bolus of B+F low-doses on demand via patient-controlled epidural analgesia (PCEA) (10-min lock-out interval and 15-mL/h limit). Clinical stage, labour characteristics and evolution, drugs used during labour, analgesic drugs used during labour and after delivery, maternal and foetal-newborn status and complications were recorded. Pain during labor was evaluated with a visual analog scale (VAS). The study was approved by local authorities and the informant consent was accepted and signed by all the included patients.

There were no differences in demographic, hemodynamic, or obstetric characteristics between the two groups. Delivery labor modes were (% in B/B+F): eutocic 24.1%/33.3%, non eutocic 75.9%/66.7% (instrumental 40.7%/28.6% and caesarean 35.2%/38.1%). B+F showed a shorter time between the beginning of the epidural analgesia induction and final delivery (1.3 h) with respect to B (p<0.05). The complementary intra-labour and post-labour analgesia requirements were lesser in B+F than in B (p<0.05): i) number of B+F PCEA bolus were B=8±1.2 and B+F=3±0.5; ii) use of intra-labour complementary analgesia were: B=35.2% vs. B+F=25.4%; iii) use of post-labour analgesia in recovery room and maternity ward were: B=36.6% vs. B+F=29.5%. Adverse reactions (RAM) incidence were (% in B/B+F): absence of RAM 59.3%/65.1%; nausea-vomiting (14.8%/20.6%), constipation (18.5%/19%), cephalalgia (3.2%/1.9%), hypertension (11.1%/3.2%), and acute renal insufficiency (7.4%/1.6%). There were no significant differences in complementary non analgesic medication between the groups, but there was a slightly more post-labour antiemetic drugs use with B+F (16.9%) than with B (9.2%). No adverse neonatal outcomes were observed in both groups.

Addition of fentanyl to bupivacaine significantly enhanced analgesia and increased the labour’s delivery eutocic rate without adverse maternal and neonatal outcomes.

Bolukbasi et al., Int J Obstet Anesth. 2005;14(4):288-293. Goring-Morris and Russell. Int J Obstet Anesth. 2006;15(2):109-114. Sah et al., J Clin Anesth. 2007;19(3):214-217