Intrathecal hyperbaric versus isobaric bupivacaine for caesarean delivery: A meta-analysis and trial sequential analysis
David Gregory Tobin, Arnab Banerjee, Madhuchanda Chatterjee, Anindya BanerjeeABSTRACT
Background and Aims:
Intrathecal bupivacaine facilitates caesarean delivery and is available in two forms: isobaric or hyperbaric with differing pharmacokinetic profiles. This meta-analysis primarily aimed to compare the incidence of hypotension (defined as a drop ≥20% from baseline systolic or mean arterial pressure) when used in caesarean delivery.
Methods:
Randomised controlled trials (RCTs) comparing intrathecal isobaric and hyperbaric bupivacaine for caesarean delivery were identified from MEDLINE, Google Scholar, and Cochrane databases. Secondary outcomes included incidence of ephedrine use, nausea/vomiting, bradycardia, maximum block height, time to maximum block height, and offset of block. Jadad scores evaluated the trials' quality. RevMan statistical software® calculated the standardised mean difference with 95% confidence intervals for continuous variables. The Mantel–Haenszel test and a random effect model were used to calculate the odds ratio for dichotomous variables. Included articles were assessed for risk of bias and consistency with Grading of Recommendations Assessment, Development, and Evaluation guidelines.
Results:
Nineteen articles with 1501 patients were analysed with 722 patients receiving isobaric bupivacaine versus 779 receiving hyperbaric bupivacaine. There was no significant difference in the rates of hypotension [odds ratio (OR) 1.25, 95% confidence interval (CI) 0.63 to 2.46] or incidence of ephedrine use (OR 1.44, 95% CI 0.75 to 2.77). There was a faster onset of motor block with hyperbaric bupivacaine (standardised mean difference -0.46, 95% CI –0.86 to –0.05) but no other differences in secondary outcomes.
Conclusion:
Despite differences between isobaric and hyperbaric bupivacaine, neither caused a significantly higher incidence of hypotension. Both produce similar clinical profiles except for onset of motor block. High levels of heterogeneity between the studies indicate the need for focused RCTs on this topic.