The Effects of Epidural Analgesia on Obstetric Outcomes, Uterine and Umbilical artery Doppler in Labor

Abstract

BACKGROUND Epidural analgesia for labor and delivery involves the injection of a local anesthetic agent and an opioid analgesic agent into the lumbar epidural space. Hypotension threatens the fetus by decreasing uterine blood flow. Modest decreases (≤ 20 %) in maternal blood pressure are of limited concern in a woman with a healthy fetus. The increase in vascular flow resistance by color Doppler (uterine artery pulsatility index) UtA-PI is positively correlated to the intrauterine pressure produced by contractions. Under normal circumstances the umbilical artery blood flow is not affected by uterine contractions. Aim of the study: This study aimed to compare the effects of epidural analgesia by using bupivacaine and fentanyl in the obstetric outcomes, uterine and umbilical artery Doppler with patients underwent normal labor. METHODS: The study included 40 full pregnant females divided into two equal groups, 20 patients for each underwent normal labor. In (group I) patients go to labor ward directly without analgesia. In (group II) patients with epidural analgesia received (bupivacaine + fentanyl). The following parameters was compared between the 2 groups: labor criteria, maternal mean arterial blood pressure, uterine artery pulsatility index (UtA-PI) during uterine contractions and relaxation, umbilical artery pulsatility index (UA-PI). RESULTS: There was a significant decrease in mean arterial blood pressure at 15, 30, 45, 60 minutes and also the (UtA-PI) was decreased at 30 and 60 minutes during contraction only. The type of delivery, the (UA-PI) and Apgar score were comparable. CONCLUSIONS: Epidural analgesia using10 ml of 0.25% bupivacaine plus 50 μg fentanyl diluted in 5 ml saline significantly decreased maternal blood pressure at 15, 30, 45, 60 minutes and the placental blood flow at 30, 60 minutes after induction only during uterine contractions but these effects not affect the umbilical blood flow, labor outcomes and neonatal outcomes. Introduction In the first stage of labor The pain is caused by uterine contractions and distension of the cervix and low uterine and is transmitted through visceral afferent (sympathetic). Labor pain is referred to the dermatomes T(11) and T(12). Later in labor perineal stretching transmits painful stimuli through the pudendal nerve and sacral nerves S2 through S4. The maternal stress response can lead to increased release of corticotropin, cortisol, norepinephrine, βendorphins, and epinephrine. [1] Epidural analgesia for labour and delivery involves the injection of a local anesthetic agent and an opioid analgesic agent into the lumbar epidural space. The injected agent gradually diffuses across the dura into the subarachnoid space, where it acts primarily on the spinal nerve roots and to a lesser degree on the spinal cord and paravertebral nerves. . The most common complications occurring with epidural analgesia is maternal hypotension. Hypotension threatens the fetus by decreasing uterine blood flow. Modest decreases (≤ 20 %) in maternal blood pressure are of limited concern in a woman with a healthy fetus. The maternal blood supply to the placenta is intermittently strangulated by myometrial contractions . A significant reduction in the perfusion pressure of the uterine artery blood flow is seen at the maximum pressure of the uterine contraction. In diastole, when intrauterine pressure exceeds maternal diastolic pressure especially if associated with hypotension, the perfusion pressure of the uterine artery blood flow is no longer present . The increase in vascular flow resistance by Doppler velocimetry as (uterine artery pustule pulsatility index) UtA-PI is positively correlated to the intrauterine pressure produced by contractions. Under normal circumstances the umbilical artery blood flow is not affected by uterine contractions . Aim of the study: This study aimed to compare the effects of epidural analgesia by using bupivacaine and fentanyl in the obstetric outcomes, uterine and umbilical artery Doppler with patients who underwent normal labor. Patients and methods This study was approved by the local Clinical Research Ethics Committee of Menoufiya hospital and written informed consent was obtained from the patients before the onset of labour analgesia. This study was performed in one year period from June 2012 till March 2013. Sixty full term pregnant females were included in the study classified as American Society of Anesthesiologists physical status I or II. The inclusion criteria included: age between 18-40 years, no significant medical or obstetric complications; normal platelet count and coagulation profile, singleton pregnancy, gestational age ≥37 weeks; with an engaged vertex presentation ; intact membrane; active labor with cervical dilatation >4 cm and uterine contractions occurring at least every 5 min; normal cardiotocography (CTG) [baseline fetal heart rate (FHR) between 110 and 160 beats/minute, baseline variability >5 beats/minute, presence of accelerations, and absence of decelerations. Exclusion criteria were: maternal age less than18 years or more than 40 years, poor parturient compliance, pre-eclampsia, gestational diabetes, cardiovascular diseases, psychiatric or neurological disorders, documented coagulation abnormality or abnormal bleeding history, evidence of infection or anatomic abnormality at catheter insertion site, delivery time is less than 120 minutes of study period, or fetal distress mandating urgent cesarean Research and Opinion in Anesthesia & Intensive Care Volume 2

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