Fetal Station May Predict the Incidence of Hypotension during Epidural Anesthesia for Cesarean Delivery
Abstract Number: 60
Abstract Type: Original Research
Introduction: Maternal hypotension complicates one-third of epidural anesthetics for cesarean delivery.(1) Understanding the risk factors for hypotension is important in order to develop better preventative measures. Laboring women have half the incidence of hypotension of elective cesarean patients, although we do not know why.(1) We hypothesize that epidural-related hypotension during cesarean delivery results from aortocaval compression and is more likely to occur if the fetal head is not engaged in the maternal pelvis. We designed this research study to determine if patients with high fetal head station have an increased rate of maternal hypotension compared to those with low fetal head station.
Methods: With IRB approval, healthy term parturients with preexisting labor epidurals who were scheduled for cesarean delivery consented to participate in this study. We collected maternal demographic, heart rate, and blood pressure (BP) data immediately before epidural dosing. We recorded cervical dilation, effacement, and station. We noted the amount of preoperative intravenous fluids given to the patient. We administered 2% lidocaine with epinephrine through the epidural catheter to achieve an adequate sensory block. Hypotension (a 20% decrease in systolic BP) was noted and promptly treated at the discretion of the provider. Assuming an overall 33% hypotension incidence, we calculated a needed sample size of 228 patients to detect a doubling of the hypotension incidence in patients with high fetal head station.
Results: We have enrolled 62 patients so far. Statistical analysis will be performed after enrollment is complete. Currently, hypotension has occurred in none of the patients with a fetal head station of +1, +2, or +3. (See Table 1)
Discussion: High fetal head station appears to be a risk factor for hypotension with epidural dosing for cesarean section. Further studies should be done to examine this phenomenon in non-laboring patients receiving neuraxial anesthesia.
1. McKinlay J, Lyons G. Int J Obstet Anesth. 2002;11:117-21.