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Phenylephrine infusion versus bolus regimens during cesarean delivery under spinal anesthesia: a double-blind randomized clinical trial to assess hemodynamic changes.
Anesth Analg. 2012 Dec; 115(6):1343-50.A&A

Abstract

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.

Authors+Show Affiliations

Department of Anesthesia and Pain Management, Mount Sinai Hospital, University of Toronto, 600 University Avenue, Room 781, Toronto, ON M5G 1X5, Canada. anneedoherty@yahoo.comNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Randomized Controlled Trial

Language

eng

PubMed ID

23011562

Citation

Doherty, Anne, et al. "Phenylephrine Infusion Versus Bolus Regimens During Cesarean Delivery Under Spinal Anesthesia: a Double-blind Randomized Clinical Trial to Assess Hemodynamic Changes." Anesthesia and Analgesia, vol. 115, no. 6, 2012, pp. 1343-50.
Doherty A, Ohashi Y, Downey K, et al. Phenylephrine infusion versus bolus regimens during cesarean delivery under spinal anesthesia: a double-blind randomized clinical trial to assess hemodynamic changes. Anesth Analg. 2012;115(6):1343-50.
Doherty, A., Ohashi, Y., Downey, K., & Carvalho, J. C. (2012). Phenylephrine infusion versus bolus regimens during cesarean delivery under spinal anesthesia: a double-blind randomized clinical trial to assess hemodynamic changes. Anesthesia and Analgesia, 115(6), 1343-50. https://doi.org/10.1213/ANE.0b013e31826ac3db
Doherty A, et al. Phenylephrine Infusion Versus Bolus Regimens During Cesarean Delivery Under Spinal Anesthesia: a Double-blind Randomized Clinical Trial to Assess Hemodynamic Changes. Anesth Analg. 2012;115(6):1343-50. PubMed PMID: 23011562.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Phenylephrine infusion versus bolus regimens during cesarean delivery under spinal anesthesia: a double-blind randomized clinical trial to assess hemodynamic changes. AU - Doherty,Anne, AU - Ohashi,Yayoi, AU - Downey,Kristi, AU - Carvalho,Jose C A, Y1 - 2012/09/25/ PY - 2012/9/27/entrez PY - 2012/9/27/pubmed PY - 2013/1/30/medline SP - 1343 EP - 50 JF - Anesthesia and analgesia JO - Anesth. Analg. VL - 115 IS - 6 N2 - 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. SN - 1526-7598 UR - https://www.unboundmedicine.com/medline/citation/23011562/Phenylephrine_infusion_versus_bolus_regimens_during_cesarean_delivery_under_spinal_anesthesia:_a_double_blind_randomized_clinical_trial_to_assess_hemodynamic_changes_ L2 - http://dx.doi.org/10.1213/ANE.0b013e31826ac3db DB - PRIME DP - Unbound Medicine ER -