Association between plain ropivacaine dose and spinal hypotension for cesarean delivery: a retrospective study.

Background: Data on the association between the plain ropivacaine dose and maternal hypotension during cesarean delivery are limited. Thus, this study aimed to explore this association.

Methods: This retrospective study included patients undergoing cesarean sections under spinal or combined spinal-epidural anesthesia with plain ropivacaine at The First Hospital of Fuyang, Hangzhou, China, between 2018 and 2022. Data were obtained from the anesthesia information management system. Liner trend tests were used to distinguish the linear relationship between spinal hypotension and the plain ropivacaine dose, and receiver operating characteristic curves were used to calculate the dose threshold. Logistic regression was used to adjust for confounders. Sensitivity analyses were performed to evaluate the stability of the results. The secondary outcome was vasopressor use (metaraminol and ephedrine).

Results: In total, 1,219 women were included. The incidence of hypotension linearly correlated with the plain ropivacaine dose (adjusted P-value for trend, P < 0.001). Thus, we used a dose threshold of 17.5 mg to compare the dose as a binary variable (≥17.5 mg vs. < 17.5 mg). Plain ropivacaine doses of ≥17.5 mg were associated with a higher incidence of spinal hypotension (adjusted odds ratio: 2.71; 95% confidence interval [1.85-3.95]; P < 0.001). The sensitivity analyses yielded similar results. The plain ropivacaine dose also correlated with metaraminol use but not ephedrine use.

Conclusions: The incidence of spinal-induced hypotension in women undergoing cesarean section linearly correlated with the plain ropivacaine dose. The dose threshold for hypotension risk was 17.5 mg.