Comparison of ultra‐low, low and high concentration local anaesthetic for labour epidural analgesia: a systematic review and network meta‐analysis

Abstract

Summary Lumbar epidural is the gold standard for labour analgesia. Low concentrations of local anaesthetic are recommended. This network meta‐analysis investigated whether further reducing the concentration of local anaesthetic can improve maternal and neonatal outcomes without compromising analgesia. We conducted a systematic search of relevant databases for randomised controlled trials comparing high (>0.1%), low (>0.08% to ≤0.1%) or ultra‐low (≤0.08%) concentration local anaesthetic (bupivacaine or equivalent) for labour epidural. Outcomes included mode of delivery, duration of labour and maternal/neonatal outcomes. Bayesian network meta‐analysis with random‐effects modelling was used to calculate odds ratios or weighted mean differences and 95% credible intervals. A total of 32 studies met inclusion criteria (3665 women). The total dose of local anaesthetic received increased as the concentration increased; ultra‐low compared with low (weighted mean difference −14.96 mg, 95% credible interval [−28.38 to −1.00]) and low compared with high groups (weighted mean difference −14.99 [−28.79 to −2.04]), though there was no difference in the number of rescue top‐ups administered between the groups. Compared with high concentration, ultra‐low concentration local anaesthetic was associated with increased likelihood of spontaneous vaginal delivery (OR 1.46 [1.18 to 1.86]), reduced motor block (Bromage score >0; OR 0.32 [0.18 to 0.54]) and reduced duration of second stage of labour (weighted mean difference −13.02 min [−21.54 to −4.77]). Compared with low, ultra‐low concentration local anaesthetic had similar estimates for duration of second stage of labour (weighted mean difference −1.92 min [−14.35 to 10.20]); spontaneous vaginal delivery (OR 1.07 [0.75 to 1.56]; assisted vaginal delivery (OR 1.35 [0.75 to 2.26]); caesarean section (OR 0.76 [0.49 to 1.22]); pain (scale 1–100, weighted mean difference −5.44 [−16.75 to 5.93]); and maternal satisfaction. Although a lower risk of an Apgar score < 7 at 1 min (OR 0.43 [0.15 to 0.79]) was reported for ultra‐low compared with low concentration, this was not sustained at 5 min (OR 0.12 [0.00 to 2.10]). Ultra‐low concentration local anaesthetic for labour epidural achieves similar or better maternal and neonatal outcomes as low and high concentration, but with reduced local anaesthetic consumption.

The 90% effective concentration of alfentanil combined with 0.075% ropivacaine for epidural labor analgesia: a single-center, prospective, double-blind sequential allocation biased-coin design

“…The study by Bader [ 7 ] showed that 0.125% bupivacaine combined with 5 μg/mL alfentanil in the clinical application of epidural labor analgesia had a rapid onset of action, definite effect and high patient satisfaction, but the concentrations of both local anesthetic and alfentanil were slightly higher than those in our study. Hallidy et al [ 13 ] showed that ultra-low concentration (≤ 0.08%) local anesthetic increased the likelihood of spontaneous vaginal delivery, reduced motor block and shortened the duration of the second stage of labor compared to high concentration local anesthetic. Therefore, in our study, 0.075% ropivacaine was used and none of the women experienced motor block.…”

Cytochrome P4503A4 gene polymorphisms guide safe sufentanil analgesic doses in pregnant Chinese mothers: a multicenter, randomized, prospective study

“…It is believed that decreased uterine activity in the second stage of labor is responsible for the increased rate of assisted instrumental delivery and risk of a low 5 min Apgar score [35,36]. Another meta-analysis indicated that the lower total local anesthetic drugs dose, the lower the probability of assisted vaginal and cesarean delivery, and the lower incidence of Apgar <7 at 1 min, however, ultra-low and high doses of anesthetic drugs can significantly shorten the first stage of labor compared to low doses, but there is no significant difference on the second stage of labor [23]. Critically, we observed no significant differences in cesarean and forceps delivery rates between groups, suggesting that delivery modes were similar across groups and that experimental sufentanil doses had no impact on these rates.…”

“…The relationship between opioids' adverse effects and drug dose has been confirmed, so clinicians believe the drug dose needs to be strictly controlled to achieve good analgesic effects and to avoid or minimize adverse drug reactions [23]. Many factors can affect the dose of drugs in clinical practice.…”

Extreme inequity in analgesia and peri‐operative management of pregnant patients

“…The obvious questions are, if all delays and barriers to receiving an epidural in labour were removed what would, or should, the rate of epidural analgesia be? Evidence from other countries and from other centres in the UK suggests a much higher epidural rate than the 25% reported by Halliday et al [6]. Modifications of this model can also be used to explain some negative outcomes associated with ethnicity in the study by O'Carroll et al [7], and more generally in other work reporting disparities in outcomes in racial and ethnically marginalised groups [22].…”