Does Cardiac Output Decrease Following Induction of Labor Analgesia?
Abstract Number: F-18
Abstract Type: Original Research
Obstetricians are always concerned about fetal heart variability that can occur after induction of labor analgesia. The etiology of fetal heart rate changes is uncertain. One of the factors implicated is decreased uterine blood flow as a result of decreased cardiac output. It is known that cardiac output decreases following induction of spinal anesthesia. However, there are no studies evaluating cardiac output changes following induction of labor analgesia. The purpose of this study is to evaluate the cardiac output changes following initiation of labor analgesia.
To date ten healthy singleton term parturients who elected regional analgesia for labor were enrolled. Patients were randomized to either epidural or combined spinal epidural (CSE) for regional analgesia. Exclusion criteria included the presence of diabetes, preeclampsia, use of beta blockers, magnesium sulphate, and category II aand III tracing. A non-invasive cardiac output monitor (Electrical Cardiometry, ICON) was used to determine hemodynamic parameters: heart rate (HR), stroke volume (SV), cardiac output (CO), systemic vascular resistance (SVR), stroke volume variation (SVV). The monitor uses four ECG sensors placed on the left side of the neck and thorax to detect changes in conductivity arising from alterations in orientation of red blood cells (RBC) within the aorta during cardiac cycle. Baseline hemodynamic parameters (SV, HR, CO, SVV, SVR) were determined for a period of 15 minutes prior to placement of neuraxial analgesia and data was collected continuously for one hour after initiation of analgesia. Parturients received either standard epidural or CSE medications. Fluid inputs and outputs were noted as well as use of vasopressors. Fetal heart rate category and patterns were automatically recorded throughout the entire length of the study and analyzed by the obstetrician (GE Centricity Perinatal System).
Results: Nine parturients completed the study. six parturients received epidural and three patients CSE analgesia. Table shows cardiac output, systolic and diastolic blood pressure data at 15 minute intervals. Both systolic and diastolic BP decreased within 15 minutes after initiation of labor analgesia. However cardiac output deceased significantly only after 30 minutes following initiation of labor analgesia. No fetal heart rate variability was observed during the study period. Further enrollment will elucidate if CSE is associated with profound decreases in CO