Phenylephrine infusion for spinal-induced hypotension in elective cesarean delivery: Does preload make a difference?

Abstract

Background and Aims:Patients undergoing elective cesarean delivery (CD) have a high-risk of spinal-induced hypotension (SIH). We hypothesized that a colloid preload would further reduce SIH when compared with a crystalloid preload.Material and Methods:Eighty-two healthy parturients undergoing elective CD were included in the study. Patients were randomly assigned to two groups (41 patients in each group) to receive either Lactated Ringer's solution (1500 ml) or hydroxyethyl starch (6% in normal saline, 500 ml) 30 min prior to placement of spinal anesthesia. All patients were treated with a phenylephrine infusion (100 mcg/min), titrated during the study.Results:There was no statistical difference between groups with regards to the incidence of hypotension (10.8% in the colloid group vs. 27.0% in the crystalloid group, P = 0.12). There was also no difference between groups with respect to bradycardia, APGAR scores, and nausea and vomiting. Significantly less phenylephrine (1077.5 ± 514 mcg) was used in the colloid group than the crystalloid group (1477 ± 591 mcg, P = 0.003).Conclusion:The preload with 6% of hydroxyethyl starch before CD might be beneficial for the prevention of SIH.

Dissecting genetic factors affecting phenylephrine infusion rates during anesthesia: a genome-wide association study employing EHR data

“…Fourth, phenylephrine infusion is frequently used to treat hypotension induced by spinal anesthesia in cesarean section [37, 38]. We excluded this group of patients because the indication and procedure are significantly different than general anesthesia and because of the prior observation that phenylephrine response in this group could be different [39, 40]. Future studies could include general or spinal anesthesia as distinct categories.…”

Colloid preloading versus crystalloid preloading to prevent hypotension after spinal anesthesia for cesarean delivery

“…Only two studies reported the requirement of phenylephrine following spinal anesthesia induced hypotension. [ 39 , 44 ] A statistically significant reduction in phenylephrine requirement was observed with the use of colloid preloading compared with crystalloid preloading (standardized mean difference: -0.54, 95% CI: -0.82 to -0.25; 169 women; I 2 = 0%, P = .0002).…”

“…The incidence of intraoperative nausea and/or vomiting was reported in 20 trials. [ 15 , 17 , 20 , 23 , 24 , 26 , 27 , 29 , 30 , 32 – 35 , 37 , 39 – 42 , 44 , 47 ] Among these trials, a statistically significant reduction in nausea and/or vomiting was found when colloid preloading was administered compared with crystalloid preloading (risk ratio: 0.72, 95% CI: 0.55–0.95; 1601 women; P = .02; Fig. 5 ) with mild heterogeneity ( I 2 = 36%).…”

“…Clinical work dating from the 2000s indicated that phenylephrine effectively reduced hypotension and was associated with less neonatal acidosis than ephedrine. [ 48 ] Nineteen studies in our review used ephedrine as the vasopressor to treat hypotension, four studies [ 37 , 39 , 44 , 45 ] used phenylephrine, one study [ 23 ] used metaraminol and one [ 26 ] used dopamine. Logically, the requirement for vasopressors is consistent with the incidence of hypotension because the drug is used to treat hypotension.…”

“…[ 5 ] This might be explained that fluid preloading alone was included in our study, and our meta-analysis covered several recent findings. [ 41 , 42 , 44 , 47 ]…”