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Randomized Controlled Trial
. 2023 Dec 6;23(1):840.
doi: 10.1186/s12884-023-06165-5.

Oxytocin infusion for maintenance of uterine tone under prophylactic phenylephrine infusion for prevention of post-spinal hypotension in cesarean delivery: a prospective randomised double-blinded dose-finding study

Xiao-Qin Jin  1 , Yao-Hua Shen  1 , Fan Fu  1 , Juan Yu  1 , Fei Xiao  2 , Xiao-Dong Huang  3
Affiliations
Randomized Controlled Trial

Oxytocin infusion for maintenance of uterine tone under prophylactic phenylephrine infusion for prevention of post-spinal hypotension in cesarean delivery: a prospective randomised double-blinded dose-finding study

Xiao-Qin Jin et al. BMC Pregnancy Childbirth. .

Abstract

Background: Prior studies have shown that, when administered as an intravenous bolus to prevent uterine atony, prophylactic phenylephrine infusion increased the dose requirement of oxytocin and second-line uterotonics. For the prevention of uterine atony, oxytocin should be delivered by continuous infusion. Here, we aimed to determine the ED50 and ED90 parameters (the effective doses for 50 and 90% patients without uterine atony) of oxytocin for co-infusion with prophylactic phenylephrine during cesarean delivery.

Methods: In this prospective randomized double-blinded dose-finding study, one hundred patients were divided into four groups to receive 2.5, 5.0, 7.5, or 10 IU/h oxytocin infusion, after the umbilical cord was clamped during the study period. The uterine tone was evaluated and defined as either adequate or inadequate. Probit regression analysis was applied to calculate the ED50 and ED90 of oxytocin infusion. Uterine tone, the percentage of patients who needed additional oxytocin bolus, second-line uterotonics, side effects, estimated blood loss, and neonatal outcomes were monitored.

Results: The estimated ED50 and ED90 values of the oxytocin infusion doses for the prevention of uterine atony were 1.9 IU/h (95% CI -4.6-3.8) IU/h and 9.3 IU/h (95% CI 7.3-16.2) IU/h, respectively. Across groups, there was a significant linear trend between the infusion dose and the percentage of patients who required additional oxytocin (p-value = 0.002). No differences were observed in the incidence of side effects and neonatal outcomes.

Conclusion: Under the conditions of this study, the ED90 of oxytocin infusion for the prevention of uterine atony was 9.3 IU/h, which is higher than the current recommendation. This finding is helpful for clinical practice, because of the routine use of phenylephrine in cesarean delivery. Further studies are needed to determine the appropriate initial bolus of oxytocin after neonatal delivery.

Trial registration: The study was registered on the Chinese Clinical Trial Register (register no. ChiCTR2200059556 ).

Keywords: Cesarean delivery; Hypotension; Oxytocin; Phenylephrine; Uterine tone.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
CONSORT flow diagram
Fig. 2
Fig. 2
Proportion of patients with adequate uterine tone at corresponding infusion dose of oxytocin
Fig. 3
Fig. 3
Dose-response curve of oxytocin at corresponding infusion dose (IU/h) for prevention uterine atony. The estimated values of ED50 and ED90 of the infusion dose of oxytocin for the prevention of uterine atony were 1.9 IU/h (95% CI: − 4.6 -3.8) IU/h and 9.3 IU/h (95% CI 7.3–16.2) IU/h, respectively
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