Vasopressors for the Management of Hypotension After Spinal Anesthesia for Elective Cesarean Section

Abstract

Topics: Pharmacology, Anesthetic ComplicationsT he choice of vasopressor to treat hypotension due to spinal anesthesia for cesarean section is controversial. For a number of years, the use of a low-dose phenylephrine infusion has been recommended to improve hemodynamic stability. However, evidence to support this recommendation is poor. pH and base excess (BE) are important outcome parameters of the newborn; and 1 systematic review has reported a significantly increased risk of lower pH and BE if ephedrine is used to treat hypotension. However, the clinical significance of this difference is unknown as the pHs reported were within the normal range regardless of whether ephedrine or phenylephrine was used. This meta-analysis was conducted to compare fetal and maternal effects of ephedrine and phenylephrine for spinal anesthesia-induced hypotension.A systematic literature search was conducted for trials comparing ephedrine and phenylephrine for hypotension treatment and the quality of the trials was scored with randomized controlled trials being weighted more in the analysis. The number of events and the total number of subjects in the ephedrine or phenylephrine groups were recorded in addition to instances of maternal hypotension, hypertension, and bradycardia, and instances of fetal acidosis defined as a pH < 7.2. Continuous parameters that were recorded were BE and arterial pCO 2 . The randomeffects model was applied in the analysis of the variables. The pooled risk ratio (RR) and 95% confidence interval (95% CI) and the weighted mean difference (WMD) of the pooled continuous data were calculated. The ephedrine group was chosen as the control group.From 133 articles, 20 were considered for further analysis and included 1069 subjects. The RR of fetal acidosis was 5.29 (95% CI, 1.62-17.25) for ephedrine compared with phenylephrine (P = 0.006). The WMD in pooled BE data was also statistically significantly lower in the ephedrine group (WMD, À1.17; 95% CI, À 2.01 to À0.33; P = 0.006). No significant difference between the 2 agents was found for umbilical artery pCO 2 (WMD, 1.60; 95% CI, À 0.41 to 3.62; P = 0.12). For the studies that reported Apgar values of <7, only 1 neonate in the ephedrine group of 1 study had an Apgar value of <7 after 5 minutes. The 1 study that reported Apgar values at 10 minutes after birth found no statistically significant differences between the ephedrine and phenylephrine groups. The risk of bradycardia was significantly lower in the women in the ephedrine group compared with those in the phenylephrine arm (RR, 0.17; 95% CI, 0.07-0.43). No significant difference was found in the risk of hypotension when the vasopressor was given prophylactically (RR, 1.13; 95% CI, 0.68-1.86; P = 0.64) or in pooled data for the vasopressors for either treatment or prevention (RR, 1.03; 95% CI, 0.72-1.48; P = 0.87). The 2 vasopressors did not differ in the risk of hypertension (RR, 1.18; 95% CI, 0.86-1.63; P = 0.30).These results support the favorable effects of phenylephrine over ephedrine for managing hy...

Comparative efficacy and safety of prophylactic norepinephrine and phenylephrine in spinal anesthesia for cesarean section: A systematic review and meta-analysis with trial sequential analysis

“…While similar meta-analyses exist, they are not entirely identical to the present study. For instance, several metaanalyses have been published on either the efficacy of multiple antihypertensive agents in spinal anesthesia (Ryu et al, 2019;Singh et al, 2020), on the comparison of phenylephrine and ephedrine (Veeser et al, 2012;Heesen et al, 2019), or on the treatment of hypotension induced by…”

“…Several meta-analyses have been published on either the efficacy of multiple antihypertensive agents in spinal anesthesia (Ryu et al, 2019;Singh et al, 2020), comparison of phenylephrine and ephedrine (Veeser et al, 2012;Heesen et al, 2019), or analyse the treatment of hypotension induced by spinal anesthesia (Kumari et al, 2022). However, our study focused on prophylaxis and not only highlights a different time point in the use of these drugs but also reflects a distinct line of thought.…”