Modern Neuraxial Anesthesia for Labor and Delivery

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.

Evaluation of Epidural Analgesia Use During Labor and Infection in Full-term Neonates Delivered Vaginally

IMPORTANCE

Quantification of potential consequences associated with the use of epidural analgesia during labor could help to improve the safety and quality of labor and delivery care for parturient women.

OBJECTIVE

To evaluate the association between epidural analgesia use during labor and neonatal infection in a large cohort of parturient women.

DESIGN, SETTING, AND PARTICIPANTS

This propensity score-matched cohort study was conducted at a university-affiliated hospital in Shanghai, China. Women at full-term pregnancy undergoing vaginal delivery between January 2013 and October 2018 were included in the study. Parturient women who were parous, experiencing premature delivery (gestational age <37 weeks), were pregnant with more than 1 fetus, or had experienced a stillbirth were excluded. Data were analyzed from October 2019 to June 2020.

EXPOSURES

The use of epidural analgesia during labor.

MAIN OUTCOMES AND MEASURES

The primary outcome was the incidence of neonatal infection, including neonatal sepsis, neonatal uncharacterized infection, neonatal pneumonia, and neonatal necrotizing enterocolitis reported in the medical record. Secondary outcomes included the incidence of maternal intrapartum fever and histologic chorioamnionitis.

RESULTS

Among 37 786 parturient women included (mean [SD] age, 29.5 [3.0] years), 19 968 (52.8%) received epidural analgesia during labor. In the propensity score-matched cohort (including 15 401 parturient women in each group), use of epidural analgesia was associated with a higher incidence of neonatal infection (absolute risk difference, 2.6%, 95% CI, 2.2%-3.0%; relative risk [RR], 2.43; 95% CI, 2.11-2.78), including higher incidence of sepsis (absolute risk difference, 0.1%, 95% CI, 0.1%-0.2%; RR, 3.50; 95% CI, 1.73-7.07) and uncharacterized infection (absolute risk difference, 2.2%, 95% CI, 1.9% to 2.6%; RR, 2.69; 95% CI, 2.30-3.15), compared with no epidural analgesia use. Use of epidural analgesia was also associated with greater incidence of maternal intrapartum fever (RR, 4.12; 95% CI, 3.78-4.50) and histologic chorioamnionitis (RR, 4.08; 95% CI, 3.59-4.64) compared with no epidural analgesia use.

CONCLUSIONS AND RELEVANCE

This cohort study found that use of epidural analgesia in full-term nulliparous women undergoing vaginal delivery was associated with an increased risk of neonatal infection, pending further investigation. These findings support efforts to further improve safety and quality of labor and delivery care for parturient women.

Women's epidural decision-making in labour: A Townsville perspective

BACKGROUND

Despite being an efficacious means of pain relief, there is a broad range of usage rates of epidural analgesia among countries worldwide. Australia sits between common usage in North America and more conservative usage in the UK. The reason for this is unclear, raising the question of whether there is a difference between Australia and other Western countries in pregnant women's attitudes toward epidural use, or the hospital context.

AIM

To explore predictors for epidural analgesia request among pregnant women in Townsville, Australia.

MATERIALS AND METHODS

A three-phase mixed methods exploratory study design, with Phase One involving 12 one-on-one interviews with pregnant and post-partum women regarding attitudes toward labour analgesia decision-making and epidural preferences. Interview data were analysed thematically to develop a survey distributed to 265 third-trimester women in Phase Two. Phase Three involved a chart review of survey participants to record delivery mode, epidural request and indication. Bivariate and logistic regression analysis of Phases Two and Three data were used to develop predictive models for epidural decision-making.

RESULTS

Interviews revealed several themes influencing analgesia preferences in Townsville women: concerns regarding personal safety, trust in health professionals, and previous experiences with labour. The logistic regression identified epidural request in labour to be predicted by: primiparity, epidural experience, induction or augmentation of labour, and perceived sense of control associated with epidural use.

CONCLUSIONS

This study suggests that the most significant influencers on Townsville women's epidural decision-making were parity, induction or augmentation of labour, previous experience of epidurals and attitude toward epidurals.

Labour analgesia; Molecular pathway and the role of nanocarriers: a systematic review

Labour is considered to be one of the most painful procedures in human experience. The most effective technique for pain relief during labour is neuraxial labour analgesia which provides analgesia without maternal or fetal sedation. Genetic predisposition may be of importance for pain perception and women experience varying degrees of pain in labour. Genetic variations in opioid receptor (OPR) genes may influence the response to epidural opioid analgesia during labour. The single-nucleotide polymorphism, A118G of the mu opioid receptor gene (oprm1), has been associated with altered pain perception. Targeted drug delivery reduces toxic side effects. Liposomes, nano-particles, nanofibres hydrogel, have been suggested to deliver anaesthetic drugs.

Bolus epidural infusion improves spread compared with continuous infusion in a cadaveric porcine spine model

BACKGROUND

The administration of epidural anesthesia during labor is a common technique used to reduce the pain of childbirth. We sought to compare standard infusion strategies of continuous epidural infusions (CEI) with programmed intermittent epidural bolus (PIEB) to assess the length of spread in terms of vertebral body length. Based on previous clinical data in humans, the PIEB was associated with improved pain control and decreased total dose of local anesthetic. We hypothesized that the PIEB was associated with increased spread when compared with CEI.

METHODS

Thirty female Yorkshire-cross swine cadavers were used to compare three infusion strategies, continuous infusion (CEI) 10 mL/hour programmed continuously, multiple bolus (MB) 2 mL given every 12 min for 10 mL total and 10 mL delivered in a single bolus (SB). Radiographs were used to identify the spread of the radiopaque contrast dye, and a number of vertebral bodies covered were measured to assess spread.

RESULTS

Overall, the CEI had an average spread of 5.6 levels, MB 7.9 and SB 10.4. The differences between SB and MB (p=0.011), SB and CEI (p<0.001) and MB and CEI (p=0.028) were all found to be significant.

CONCLUSIONS

We demonstrated increased spread of epidural contrast with programmed intermittent bolus strategies. This supports previous evidence of improved patient outcomes with PIEB strategy compared with CEI, and encourages the use of PIEB in the appropriate patient population.

Cadaveric Porcine Spines as a Model for the Human Epidural Space

Most patients who undergo epidural anesthesia are pregnant and thus a protected population, which has limited investigations of the human epidural space. Among the several species studied as models for the human spine, the porcine spine has been used as a model for spine instrumentation. Although the spread of colored dye within the porcine epidural space has been investigated, no model has demonstrated in situ spread by using radiopaque contrast dye. To this end, we here used 10 Yorkshire swine cadavers through an approved tissue sharing agreement. Epidural catheters were placed by using a landmark-based loss-of-resistance technique; placement was confirmed through radiography. The catheters were connected to epidural infusion pumps to ensure consistent dosing, 2-mL boluses of contrast dye were injected into the space, and radiographs were taken and recorded after each bolus. The total spread of the contrast dye was analyzed. We demonstrated consistent and reliable spread of fluid in the epidural space among the animals used, with low variability between animals of different weights. Our results support the use of the epidural space of cadaveric swine as a model for the human epidural space. Furthermore, the technique for epidural administration by using the landmark-based loss-of-resistance demonstrated in this model was validated, thus supporting future investigations of medication delivery into the epidural space.