Postoperative Analgesic Effectiveness of Peripheral Nerve Blocks in Cesarean Delivery: A Systematic Review and Network Meta-Analysis

Peripheral nerve blocks for analgesia following cesarean delivery A narrative review

Spinal and epidural blocks are commonly employed for pain relief during and following cesarean section. Intrathecal morphine (ITM) has been the gold standard for the same for many years. In recent times, many peripheral nerve blocks (PNBs) have been tried for postoperative analgesia following cesarean delivery (PACD). This article has reviewed the common PNBs used for PACD. The role of PNBs along with ITM has been studied and the current best strategy for PACD has also been explored. Currently, Ilio-inguinal nerve and anterior transversus abdominis plane block in conjunction with intrathecal morphine have been found to be the most effective strategy, providing lower rest pain at 6 hours as compared to ITM alone. In patients not receiving intrathecal morphine, recommended PNBs are lateral transversus abdominis plane block, single shot local anesthetic wound infiltration, or continuous wound infiltration with catheter below rectus fascia. PNBs are recommended for PACD. They have an opioid-sparing effect and are devoid of adverse effects associated with central neuraxial blocks such as hypotension, bradycardia, and urine retention. However, caution must be observed with PNBs for possible local anesthetic toxicity due to the large volumes of drug required.

Regional Analgesia for Cesarean Delivery: A Narrative Review Toward Enhancing Outcomes in Parturients

Introduction

With the current surge on peripheral nerve blocks in post-cesarean pain management and the historical lack of unequivocal evidence supporting its universal use, this review intended to re-examine the extended scope of literature on regional anesthesia and postoperative analgesia in low-transverse cesarean section.

Methods

A literature search was conducted up to April 2023 using PubMed to identify articles relevant to our search words "cesarean section", "neuraxial morphine", "post-cesarean analgesia", as well as the name of each individual nerve block. The literature search was ultimately narrowed to systematic reviews and randomized controlled trials published between 2012 and 2023. We define, describe, and discuss the evidence surrounding each individual regional anesthetic technique in the presence and absence of intrathecal morphine, which is used as the gold standard when appropriate.

Results

In the absence of neuraxial morphine, all regional anesthetic techniques have some level of analgesic benefit in the post-cesarean analgesia. Transversus Abdominis Plane blocks continue to have the most studies in their use. Newer fascia plane blocks including the anterior Quadratus Lumborum, and Erector Spinae Plane blocks provide significant analgesia. In addition, direct comparison among peripheral nerve blocks consistently favors the more proximal, centralized techniques. Conversely, in the presence of neuraxial morphine, no peripheral anesthetic technique has reliably and reproducibly demonstrated an added analgesic benefit regardless of the peripheral nerve block technique or location of local anesthetic injection in the post-cesarean population.

Conclusion

Neuraxial morphine continues to be the gold standard for post-cesarean section analgesia, the benefit of additional single injection regional anesthetic is currently not evidence supported. In cases where neuraxial opioids have not or cannot be given, there is overwhelming evidence that regional anesthetic techniques improve post-cesarean section analgesia and decrease post-operative opioid consumption. Even though there is no consensus on the optimal peripheral nerve block, emerging evidence suggests more centralized abdominal fascia plane block trends towards better analgesia.

Analgesia after cesarean section - what is new?

PURPOSE OF REVIEW

Cesarean section is the most frequent surgical intervention, and pain following cesarean delivery unfortunately remains a common issue. The purpose of this article is to highlight the most effective and efficient options for postcesarean analgesia and to summarize current guidelines.

RECENT FINDINGS

The most effective form of postoperative analgesia is through neuraxial morphine. With adequate dosing, clinically relevant respiratory depression is extremely rare. It is important to identify women with increased risk of respiratory depression, as they might require more intensive postoperative monitoring. If neuraxial morphine cannot be used, abdominal wall block or surgical wound infiltration are very valuable alternatives. A multimodal regimen with intraoperative intravenous dexamethasone, fixed doses of paracetamol/acetaminophen, and nonsteroidal anti-inflammatory drugs reduce postcesarean opioid use. As the use of postoperative lumbar epidural analgesia impairs mobilization, double epidural catheters with lower thoracic epidural analgesia are a possible alternative.

SUMMARY

Adequate analgesia following cesarean delivery is still underused. Simple measures, such as multimodal analgesia regimens should be standardized according to institutional circumstances and defined as part of a treatment plan. Neuraxial morphine should be used whenever possible. If it cannot be used, abdominal wall blocks or surgical wound infiltration are good alternatives.

Efficacy and safety of different doses of epidural morphine coadministered with low-concentration ropivacaine after cesarean section: A retrospective cohort study

Objective: The optimal dose of epidural morphine after cesarean section (CS) still remains unknown when combined with low-concentration ropivacaine based on a continuous basal infusion (CBI) mode. The aim of this study was to assess the impact of different dose of epidural morphine plus ropivacaine on maternal outcomes.

Materials and methods: Data of parturients who received epidural analgesia for CS at a teaching hospital from March 2021 to June 2022 were retrospectively collected. Parturients were divided into two groups (RM3 group and RM6 group) according to different medication regimens of morphine. The implementation of epidural analgesia was performed with 3 mg morphine in RM3 group and 6 mg morphine in RM6 group in combination with 0.1% ropivacaine via a CBI pump. The primary outcomes included pain intensity at rest and movement and the incidence of urinary retention and pruritus within postoperative 48 h. The secondary outcomes included the incidence and severity of postoperative nausea and vomiting (PONV) and pruritus, the rate of rescue analgesia and grading of motor Block.

Results: Totally, 531 parturients were eligible for the final analysis, with 428 and 103 parturients in the RM3 group and RM6 group, respectively. There were no statistically significant differences in the visual analogue scores (VAS) at rest and movement within postoperative 48 h between the two groups (all p > 0.05). Compared with the RM6 group, the incidence of urinary retention was lower in the RM3 group within 48 h after CS (4.0% vs. 8.7%, p = 0.044). No significant difference was found in the incidence and severity of PONV and pruritus, the rate of rescue analgesia and grading of motor block between RM3 and RM6 groups.

Conclusion: Epidural 3 mg morphine plus 0.1% ropivacaine in a CBI mode can provide equal efficacy and have lower incidence of urinary retention compared with 6 mg morphine after CS.

Perioperative management of acute myocardial infarction in the 31st week of pregnancy: A case report and literature review

Pregnancy-related acute myocardial infarction (PAMI) is rare but life-threatening. The incidence of PAMI is growing over time for multiple reasons, and the management of parturients with acute myocardial infarction is challenging in terms of diagnosis and treatment. To date, there are still no clear guidelines on the best practice for PAMI. We present a case of a 41-year-old woman with PAMI at 31 weeks of pregnancy. Through multidisciplinary collaboration, successful outcomes were achieved for both the mother and fetus.