///2015 Abstract Details
2015 Abstract Details2019-08-02T16:54:43-05:00

Phenylephrine infusion versus phenylephrine bolus alone in elective cesarean section after spinal (or CSE) anesthesia.

Abstract Number: T-48
Abstract Type: Original Research

Mary C Zoccoli B.S., M.D.1 ; Idiana Mejias-Rodriguez M.D.2; Austin Pulliam M.D.3; Christopher James M.D.4; Kristen Vanderhoef M.D.5


Phenylephrine has been shown to be as effective as ephedrine for treating maternal hypotension following spinal anesthesia for cesarean section, with improved fetal acid-base status. With a high incidence of hypotension in elective cesarean section patients under spinal anesthesia, prophylactic phenylephrine variable rate infusion regimens have been used as treatment. Multiple variable rate regimens have been described with mixed results.


We present a retrospective review comparing a phenylephrine variable rate infusion regimen adjusted to changes in arterial blood pressure and heart rate to traditional bolus injections alone observing the hemodynamic profiles of both groups, particularly the incidence and degree of hypotension and status of the newborn. We reviewed all elective cesarean sections performed at our institution from May, 2014 through January, 2015 under spinal or combined spinal epidural (CSE) anesthesia. Some anesthesia staff began implementing a phenylephrine infusion following neuraxial blockade in elective cesarean sections in an attempt to ameliorate the peaks and troughs often seen when treating hypotension with bolus dosing alone. For each group, we identified 1) initial baseline blood pressure in the operating room prior to the block, 2) the lowest blood pressure recorded after intrathecal injection, 3) episodes of hypotension defined as a 20% decrease from baseline, 4) the total number of hypotensive episodes prior to delivery of the fetus, 5) total phenylephrine dose administered and 6) APGARS at 1 and 5 minutes. The phenylephrine infusion was started at 50 mcg/min, with incremental increases or decreases of 25 mcg/min titrated to blood pressure measured every minute. Rescue bolus dosing of 50-100 mcg was noted in some cases. In the control group, bolus dosing of 50-200 mcg of phenylephrine was given incrementally as determined by the clinician.


186 patients met our inclusion criteria. 66 were in the infusion group and 117 were controls. 99 patients (53%) had combined spinal epidural (CSE) while 87(47%) had single-shot spinals with 12mg of 0.75% bupivacaine, 10-20 mcg of fentanyl and 150-200 mcg of DuramorphR. Our preliminary data was significant for 108 patients (58%) with pre-delivery hypotension. 69of these patients (64%) were in the control group and 39 (36%) in the infusion group. The infusion regimen required a higher total dose of phenylephrine compared to controls, but with a lower incidence of hypotension and fewer episodes prior to delivery (exact number currently being extracted from the data). Neonatal outcomes or APGAR scores were not different between the two groups.


Our preliminary data shows that prophylactic variable rate phenylephrine infusion with intermittent rescue bolusing is more effective than bolus dosing alone with respect to maintaining blood pressure and clinician workload.

References: Allen et al, Anesth Analg 2010. Key et al, Anest

SOAP 2015