Phenylephrine infusion versus bolus regimens during cesarean delivery under spinal anesthesia: a double-blind randomized clinical trial to assess hemodynamic changes

Anne Doherty, Yayoi Ohashi, Kristi Downey, Jose C A Carvalho
Anesthesia and Analgesia 2012, 115 (6): 1343-50

INTRODUCTION: Phenylephrine is used to prevent and treat hypotension during spinal anesthesia for cesarean delivery. The optimal administration regimen is undetermined. We used a Non-invasive cardiac output monitor to test the hypothesis that a fixed-rate phenylephrine infusion regimen would cause a smaller reduction in maternal cardiac output, and result in less maternal hypotension, as compared to a phenylephrine bolus regimen.

METHODS: This was a double-blind, randomized clinical trial of women undergoing elective cesarean delivery under spinal anesthesia. Patients were randomized to an intermittent bolus (120 μg) or a fixed-rate infusion (120 μg/min) regimen of phenylephrine. Any decrease in systolic blood pressure from baseline was treated. The primary outcome was the maximum change in cardiac output in the predelivery period, assessed using bioreactance technology. Secondary outcomes included the maximum change in heart rate, incidence of hypo- and hypertension, nausea/vomiting and bradycardia, total dose of phenylephrine, umbilical blood gases, and Apgar scores. The hemodynamic profiles over time in each treatment arm were compared.

RESULTS: Sixty patients were studied. There was no significant difference in the maximum change in cardiac output between the 2 treatment arms: mean (SD) maximum change in cardiac output in the bolus group was 1.87 (1.68) L/min versus 1.9 (1.46) L/min in the infusion group (P = 0.94) (95% confidence intervals of difference in means: -0.84 to 0.78 L/min). The infusion group received significantly more phenylephrine (1740 (613) versus 964 (454) μg) (P < 0.001). In the initial 6 min after intrathecal injection, there was a significant decrease in blood pressure in the infusion group compared to the bolus group (P = 0.007). There was no significant difference in the other secondary outcomes.

CONCLUSION: There were no clinical benefits to administering phenylephrine as an infusion versus a bolus regimen. The bolus regimen maintained maternal arterial blood pressure closer to baseline in the initial minutes after spinal injection but this had no clinical benefits. The infusion regimen required a higher total dose of phenylephrine to maintain maternal arterial blood pressure at baseline during the predelivery period.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"