Local Anesthetic Requirements Are Greater in Dystocia Than in Normal Labor

Abstract

These data suggest that an increased local anesthetic requirement for epidural labor analgesia is associated with more intense pain related to dystocia. Women in early, clinically normal labor but who later develop dystocia require more local anesthetic and, by inference, are experiencing more severe pain than women who deliver vaginally. This association should be considered when studying the relation between the method of labor analgesia and the course of labor.

Genetic variability of the μ-opioid receptor influences intrathecal fentanyl analgesia requirements in laboring women ☆

“…Individual patient outcomes were categorized as success, failure, or rejection, similar to previous minimal local analgesic concentration (MLAC) [12] and minimal analgesic dose (MAD) [33] methodologies. The MLAC methodology has been extensively used in obstetric anesthesia investigations to assess differences in potencies and analgesic responses both to opioids and local anesthetics [1,6,12,13,31,[36][37][38]39,40,41]. We used the same criteria to define successful analgesia or failure as those used in previous studies assessing median effective doses of opioids or local anesthetics, as indicated below:…”

A retrospective case-controlled study of the association between request to discontinue second stage labor epidural analgesia and risk of instrumental vaginal delivery

“…4 Increased analgesic requirements have been demonstrated to be associated with dysfunctional labor, although it is unlikely that the dysfunctional labor was caused by the epidural per se. 6 Other investigators have found that fetal head malposition did not differ in parturients with and without neuraxial analgesia when stratified by mode of delivery. 7 There are multiple limitations of our study design and conclusions.…”

Impact of the addition of sufentanil 5 μg or clonidine 75 μg on the minimum local analgesic concentration of ropivacaine for epidural analgesia in labour: a randomized comparison

“…Dystocia leading to caesarean section is associated with increased local anaesthetic requirements in early labour. 34 Similarly, progression of labour significantly increases local anaesthetic requirements assessed by the MLAC methodology. 35 Inversely, obese patients have been demonstrated to have lower local anaesthetic requirements for epidural analgesia in labour.…”