Maternal hemodynamics during labor epidural analgesia with and without adrenaline: a secondary analysis of a randomized trial

Abstract

Background: Pregnancy in general and labor in particular is associated with changes in maternal hemodynamic parameters such as increased cardiac output and heart rate, with peaks during uterine contractions. Adrenaline may be added to labor epidural solutions to enhance efficiency, but the hemodynamic fluctuations may increase. The aim of this study was to compare the hemodynamic changes of epidural drug solution with or without adrenaline 2 µg.ml-1and to provide pilot data for a larger study.Methods:Forty-one nulliparous laboring women requesting epidural analgesia were randomized to epidural solution of bupivacaine 1mg.ml-1, fentanyl 2 µg.ml-1 with or without adrenaline 2 µg.ml-1. The participants were monitored with the Nexfin CC continuous non-invasive blood pressure and cardiac output monitor. The primary outcomes were changes in peak systolic blood pressure and cardiac output at uterine contraction within 30 minutes after epidural activation. The effect of adrenaline was tested statistically by a linear mixed effects model of the outcome variables’ dependency on time, adrenaline and their interaction. Results:The addition of adrenaline to the solution had no statistically significant effect on the temporal changes in peak systolic blood pressure (mean change 0.23 mmHg.min-1 95% CI [-0.17; 0.64] p=0.26), peak cardiac output (mean change 0.0029 l.min-1.min-1 95 % CI [-0.026; 0.032] 0.84), or heart rate (mean change 0.015 beats.min-1 .min-1 95 % CI [-0.25; 0.28] p=0.91). Conclusion:The addition of adrenaline 2 µg.ml-1to the epidural solution does not seem to have clinically significant influences on the maternal hemodynamics during labor.Trial registration:This trial was registered at clinicaltrials.gov (NCT00685672) May 28th 2008.