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. 2024 Jul-Sep;40(3):491-497.
doi: 10.4103/joacp.joacp_189_23. Epub 2024 Mar 28.

Minimum effective dose of intrathecal hyperbaric bupivacaine for cesarean section with and without prophylactic norepinephrine infusion: Randomized triple-blinded trial

Asha Tyagi  1 , Monika Mathur  1 , Rashmi Salhotra  1 , Rajesh S Rautela  1
Affiliations

Minimum effective dose of intrathecal hyperbaric bupivacaine for cesarean section with and without prophylactic norepinephrine infusion: Randomized triple-blinded trial

Asha Tyagi et al. J Anaesthesiol Clin Pharmacol. 2024 Jul-Sep.

Abstract

Background and aims: Vasopressor usage can affect the rostral spread of intrathecal drug and, hence, its requirement during cesarean delivery. Although a decreased spread is evidenced with phenylephrine, there is no data for norepinephrine usage. The present study aimed to evaluate the minimum effective dose of intrathecal hyperbaric bupivacaine for cesarean section with and without prophylactic norepinephrine infusion.

Material and methods: Patients scheduled for elective cesarean section under combined spinal-epidural block were randomized to receive intravenous infusion of norepinephrine (0.05 μg/kg/min) or normal saline (placebo), initiated immediately after intrathecal injection. Postspinal hypotension in either group (systolic arterial pressure ≤0.8 baseline) was treated with norepinephrine 4 μg rescue. Dose of intrathecal hyperbaric bupivacaine (0.5%) was decided for individual patients using up-and-down sequential allocation method. Primary outcome measure was the minimum effective dose of intrathecal hyperbaric bupivacaine (0.5%) defined as ED50, while secondary observations included spinal block characteristics and neonatal outcomes.

Results: Demographic parameters were statistically similar between both groups (P > 0.05). ED50 of intrathecal hyperbaric bupivacaine was 7.8 mg (95% confidence interval [CI]: 6.7-8.8) and 7.4 mg (95% CI: 6.1-8.7) for normal saline and norepinephrine group respectively (P = 0.810). Block characteristics were similar between both groups as was neonatal APGAR score, but umbilical artery base excess was greater for norepinephrine versus normal saline group (-4.4 ± 3.6 vs. -6.5 ± 2.4, P = 0.038).

Conclusion: Use of prophylactic norepinephrine (0.05 μg/kg/min) during cesarean delivery does not require adjustment of intrathecal hyperbaric bupivacaine.

Keywords: Cesarean section; ED50; intrathecal dose; norepinephrine; vasopressor.

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Conflict of interest statement

There are no conflicts of interest.

Figures

Figure 1
Figure 1
CONSORT flow chart. BMI = body mass index
Figure 2
Figure 2
Sequence for doses of hyperbaric bupivacaine in (a) normal saline and (b) norepinephrine group (with ED50). ◊Inadequate block; ♦Adequate block
See this image and copyright information in PMC

References

    1. Ngan Kee WD, Khaw KS, Lee BB, Lau TK, Gin T. A dose response study of prophylactic intravenous ephedrine for the prevention of hypotension during spinal anaesthesia for delivery. Anesth Analg. 2000;90:1390–5. - PubMed
    1. Kinsella SM, Carvalho B, Dyer RA, Fernando R, McDonnell N, Mercier FJ, et al. International consensus statement on the management of hypotension with vasopressors during caesarean section under spinal anaesthesia. Anaesthesia. 2018;73:71–92. - PubMed
    1. Ngan Kee WD, Lee SWY, Ng FF, Khaw KS. Prophylactic norepinephrine infusion for preventing hypotension during spinal anesthesia for cesarean delivery. Anesth Analg. 2018;126:1989–94. - PubMed
    1. Hasanin A, Amin S, Refaat S, Habib S, Zayed M, Abdelwahab Y, et al. Norepinephrine versus phenylephrine infusion for prophylaxis against post-spinal anaesthesia hypotension during elective caesarean delivery: A randomised controlled trial. Anaesth Crit Care Pain Med. 2019;38:601–7. - PubMed
    1. Ngan Kee WD, Lee SW, Ng FF, Tan PE, Khaw KS. Randomized double-blinded comparison of norepinephrine and phenylephrine for maintenance of blood pressure during spinal anesthesia for cesarean delivery. Anesthesiology. 2015;122:736–45. - PubMed

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