Modern techniques to optimize neuraxial labor analgesia

Modern labor epidural analgesia: implications for labor outcomes and maternal-fetal health

Epidural analgesia is an important means of pain control during labor throughout the world. Over its historic development, it has been implicated in several undesirable outcomes, including prolongation of labor and increased need for operative delivery. These effects have emerged in some retrospective and observational studies, but such methods of investigation are highly prone to bias and are particularly ill-suited for the study of labor analgesia. In high-quality studies, including Cochrane reviews and meta-analyses, epidural analgesia has been suggested to extend the first stage of labor by 30 minutes and the second stage by 15 minutes, when compared with alternative forms of analgesia. Although this may be a reproducible effect, it may be argued that it is clinically negligible. With respect to mode of delivery, similar high-quality studies have consistently shown no increased risk of cesarean delivery associated with epidural analgesia. Some forms of epidural analgesia were associated with higher risk of assisted vaginal delivery, but the use of newer modalities has been shown to abolish this effect. Specific advancements have centered on reducing total anesthetic consumption, given that local anesthetic-induced motor block is theorized to interfere with maternal expulsive efforts in the second stage of labor. These measures include the use of low-concentration local anesthetic solutions equivalent to ≤0.1% bupivacaine, shown in meta-analyses to lead to no higher risk of assisted vaginal delivery relative to nonepidural analgesia. Additional advancements in the maintenance of analgesia include programmed intermittent epidural bolus and patient-controlled epidural analgesia, the combination of which has been shown to reduce the risk of assisted vaginal delivery, also likely mediated by reduction in local anesthetic dose. These techniques have gained popularity in the past two decades, such that studies published since 2005 show no higher risk of assisted vaginal delivery with epidural than with opioid analgesia (as reported in a Cochrane review). Labor epidural analgesia has implications for maternal and fetal health perinatally. It is known to result in transient maternal hypotension (particularly with initiation), which may progress to the level of necessitating fluid or vasopressor therapy. This is not clearly associated with any adverse outcomes. There is also a consistently higher incidence of fever in parturients receiving neuraxial anesthesia, likely of noninfectious origin, which has similarly not been associated with adverse neonatal outcomes. Finally, neonates of parturients who receive epidural analgesia have been shown to have no worse Apgar scores and more favorable acid-base status than their counterparts. These observations should serve to reassure providers that modern labor analgesia, as currently understood, is not consistently associated with any significant adverse outcomes for the parturient or fetus. In this review, we describe variations of modern labor epidural analgesia, conduct an in-depth review of current literature on its use, and explore the most up-to-date evidence on its implications for the progression and outcomes of labor, including the pertinent maternal and fetal side effects.

Neuraxial labor analgesia: Maintenance techniques

Since the advent of neuraxial analgesia for labor, approaches to maintaining intrapartum pain relief have seen significant advancement. Through pharmacologic innovations and improved drug delivery mechanisms, current neuraxial labor analgesia maintenance techniques have been shaped by efforts to maximize patient comfort during the birthing process, while minimizing undesirable side effects and promoting the unimpeded progress of labor. To these ends, a modern anesthesiologist may avail themselves of several techniques, including programmed intermittent epidural bolus (PIEB), patient controlled epidural analgesia (PCEA) and dilute concentration local anesthetic + opioid epidural solutions. We explore the historical development and the evidential underpinnings of these techniques, in addition to several contemporary neuraxial labor analgesia practices. We also summarize current understanding of the effects these interventions have on maternal/fetal health and the labor course, as well as several important aspects of analgesic safety and monitoring.

Anesthetic management of obese and morbidly obese parturients

The prevalence of obese parturients is increasing worldwide. This review describes safe analgesic techniques for labor and anesthetic management during cesarean sections in obese parturients. The epidural analgesic technique is the best way to provide good pain relief during the labor phase and can be easily converted to a surgical anesthetic condition. However, the insertion of the epidural catheter in obese parturients is technically more difficult compared to that in non-obese parturients. The distance from the skin to the epidural space increases in proportion to the body mass index (BMI): 4.4 cm in mothers of normal weight and 7.5 cm in mothers with BMI 50 and above. Neuraxial blocks are the ideal anesthetic methods and gold standard techniques for cesarean section in pregnant women with obesity. Single-shot spinal anesthesia is the most common type of anesthesia used for cesarean sections. The advantage of single-shot spinal anesthesia is a dense-sufficient block of rapid onset. A combined spinal-epidural (CSE) anesthetic technique is also recommended as an attractive alternative method. In obese parturients, the operation time can be longer than expected, and therefore, the CSE technique provides the advantage of rapid onset and intense block for prolonged operation with postoperative pain control. The risk of postoperative complications is very high in obese parturients. Therefore, detailed communication of the parturient's medical condition and the details of surgery and anesthesia between the anesthesiologist and obstetrician is important prior to cesarean section in obese pregnant women.