A systematic review of the effects of adding neostigmine to local anesthetics for neuraxial administration in obstetric anesthesia and analgesia

Comparison of adjuvant pharmaceuticals for caudal block in pediatric lower abdominal and urological surgeries: A network meta-analysis

STUDY OBJECTIVE

Caudal block helps relieve pain after sub-umbilical surgery in pediatric patients; however, the duration for which it exerts its analgesic effect is limited. The addition of certain adjuvant agents to local anesthetics (LAs) that are used to administer caudal block can prolong postoperative analgesia. Therefore, we aimed to compare the efficiencies and side effects of caudal adjuvants in the settings of pediatric lower abdominal and urological surgeries.

DESIGN

A network meta-analysis (NMA).

PATIENTS

One hundred and twelve randomized controlled trials (RCTs) involving 6800 pediatric patients were included in the final analysis.

INTERVENTIONS

Different adjuvant agents, namely clonidine, dexamethasone, dexmedetomidine, fentanyl, ketamine, magnesium, midazolam, morphine, neostigmine, and tramadol.

MEASUREMENTS

The primary outcome was the duration of analgesia. The secondary outcomes included the requirement for additional analgesia, analgesic consumption, and postoperative complications. The effects and rankings were evaluated using NMA and the surface under the cumulative ranking curve scores, respectively.

RESULTS

Neostigmine, dexmedetomidine, and dexamethasone were found to be the three most effective adjuvants that prolong the duration of analgesia for caudal block, and these adjuvants extended this duration by 8.9 h (95% confidence interval [CI], 7.1-10.7), 7.3 h (95% CI, 6.0-8.6), and 5.9 h (95% CI, 4.0-7.7), respectively. Caudal neostigmine was associated with an increase in the incidence of postoperative nausea and vomiting, whereas dexmedetomidine and dexamethasone showed no postoperative complications.

CONCLUSIONS

This NMA provided evidence and suggested that dexmedetomidine and dexamethasone may be the most beneficial adjuvant pharmaceutics adding to LAs for caudal block in children. However, given the off-label status of caudal dexmedetomidine and dexamethasone, further high-quality RCTs are still warranted, especially to determine whether delayed neurological complications will occur.

Epidural analgesia in labor: A narrative review

Lumbar epidural is the most effective form of pain relief in labor with around 30% of laboring women in the UK and 60% in the USA receiving epidural analgesia. Associations of epidural on maternal, obstetric, and neonatal outcomes have been the subject of intense study, though a number of uncertainties persist. The present narrative review explores important areas of research surrounding epidural analgesia in obstetric patients including methods of initiation and administration, choice of local anesthetic solution, and the addition of adjuvants. Key meta-analyses exploring associations of epidural analgesia on maternal and neonatal outcomes are identified and summarized.

Cholinergic modulation is independent of T lymphocytes in a mouse model of neuropathic pain

T lymphocytes are increasingly implicated in pain signaling. A subset of T lymphocytes, termed TChAT, express the rate-limiting enzyme for acetylcholine (ACh) production, choline acetyltransferase (ChAT), and mediate numerous physiological functions. Given that cholinergic signaling has long been known to modulate pain processing and is the basis for several analgesics used clinically, we asked whether TChAT could be the intersection between T lymphocyte and cholinergic mediation of pain signaling. In this study, we used a mouse gene knockout strategy to ablate ChAT specifically from T lymphocytes and examined the development and expression of mechanical and thermal hypersensitivity in a spared nerve injury (SNI) mouse model of neuropathic pain. We found that mice with ChAT knockout in T cells (floxed Chat plus CD4-Cre recombinase) did not differ from control mice with intact ChAT (floxed Chat, but no Cre recombinase) in their expression of mechanical sensitivity before or after injury. Similarly, thermal sensitivity was unaffected after injury, with control mice expressing similar patterns of thermal preference to mice whose T cells do not express ChAT. Our experiments demonstrate that cholinergic signaling initiated by T lymphocytes neither dampens nor exacerbates the expression of mechanical or thermal sensitivity in neuropathic mice. Thus, while both cholinergic signaling and T lymphocytes have established roles in modulating pain phenotypes, it is not cholinergic signaling initiated by T lymphocytes that drive this. Our findings will help to narrow in on which aspects of T-cell modulation may prove useful as therapies.

Pharmacological and clinical implications of local anaesthetic mixtures: a narrative review

Various techniques have been explored to prolong the duration and improve the efficacy of local anaesthetic nerve blocks. Some of these involve mixing local anaesthetics or adding adjuncts. We did a literature review of studies published between 01 May 2011 and 01 May 2021 that studied specific combinations of local anaesthetics and adjuncts. The rationale behind mixing long- and short-acting local anaesthetics to hasten onset and extend duration is flawed on pharmacokinetic principles. Most local anaesthetic adjuncts are not licensed for use in this manner and the consequences of untested admixtures and adjuncts range from making the solution ineffective to potential harm. Pharmaceutical compatibility needs to be established before administration. The compatibility of drugs from the same class cannot be inferred and each admixture requires individual review. Precipitation on mixing (steroids, non-steroidal anti-inflammatory drugs) and subsequent embolisation can lead to serious adverse events, although these are rare. The additive itself or its preservative can have neurotoxic (adrenaline, midazolam) and/or chondrotoxic properties (non-steroidal anti-inflammatory drugs). The prolongation of block may occur at the expense of motor block quality (ketamine) or block onset (magnesium). Adverse effects for some adjuncts appear to be dose-dependent and recommendations concerning optimal dosing are lacking. An important confounding factor is whether studies used systemic administration of the adjunct as a control to accurately identify an additional benefit of perineural administration. The challenge of how best to prolong block duration while minimising adverse events remains a topic of interest with further research required.

The effective interplay of (non-) selective NSAIDs with neostigmine in animal models of analgesia and inflammation

BACKGROUND

Surgical procedures cause perioperative immunosuppression and neuroendocrine stress, exerted by activation of the autonomic nervous system and the hypothalamic-pituitary-adrenal axis. The acetylcholinesterase inhibitor (ACHEI); neostigmine, is known clinically for its analgesic effect in the perioperative phases proving high efficacy; besides possessing anti-inflammatory properties controlling immune cells and cytokine level. Hence, this study evaluated and compared the analgesic and anti-inflammatory activities of the combination of selective Cox-2 inhibitor; celecoxib, with neostigmine versus a combination of the non-selective Cox inhibitor; diclofenac, with neostigmine; in different experimental models of analgesia and inflammation in rats.

METHODS

Analgesic activity of neostigmine with/without diclofenac or celecoxib was assessed in female Sprague-Dawely rats using the tail clip model and acetic acid induced writhing. Serum level of β-endorphin was assessed after the tail clip test. The anti-inflammatory activity was evaluated using acute and sub-chronic formalin induced paw edema. At the end of the sub-chronic formalin test, blood samples were collected for analysis of anti-inflammatory, liver and kidney function markers. Livers, kidneys and hind paws were also examined histopathologically.

RESULTS

Addition of neostigmine to selective or non-selective NSAIDs (celecoxib or diclofenac) causes an increased level of analgesia of NSAIDs with rapid onset of action and short duration, while causing potentiation of the anti-inflammatory effect of neostigmine as seen in the tail clip, writhing, formalin test, Cox-1 and Cox-2 activities, serum β-endorphin, TNF-α, NF-кB and HS-CRP. All combinations of this study disturb some kidney and liver functions, however with normal histopathological appearances, while hind paws reveal improved inflammatory infiltration in all treated groups.

CONCLUSIONS

Selective and non-selective NSAIDs examined in this study could be good adjunct options to general anesthetic agents and neostigmine in perioperative stages, an outcome that needs further clinical investigations.

PROSPECT guideline for elective caesarean section: updated systematic review and procedure-specific postoperative pain management recommendations

Caesarean section is associated with moderate‐to‐severe postoperative pain, which can influence postoperative recovery and patient satisfaction as well as breastfeeding success and mother‐child bonding. The aim of this systematic review was to update the available literature and develop recommendations for optimal pain management after elective caesarean section under neuraxial anaesthesia. A systematic review utilising procedure‐specific postoperative pain management (PROSPECT) methodology was undertaken. Randomised controlled trials published in the English language between 1 May 2014 and 22 October 2020 evaluating the effects of analgesic, anaesthetic and surgical interventions were retrieved from MEDLINE, Embase and Cochrane databases. Studies evaluating pain management for emergency or unplanned operative deliveries or caesarean section performed under general anaesthesia were excluded. A total of 145 studies met the inclusion criteria. For patients undergoing elective caesarean section performed under neuraxial anaesthesia, recommendations include intrathecal morphine 50–100 µg or diamorphine 300 µg administered pre‐operatively; paracetamol; non‐steroidal anti‐inflammatory drugs; and intravenous dexamethasone administered after delivery. If intrathecal opioid was not administered, single‐injection local anaesthetic wound infiltration; continuous wound local anaesthetic infusion; and/or fascial plane blocks such as transversus abdominis plane or quadratus lumborum blocks are recommended. The postoperative regimen should include regular paracetamol and non‐steroidal anti‐inflammatory drugs with opioids used for rescue. The surgical technique should include a Joel‐Cohen incision; non‐closure of the peritoneum; and abdominal binders. Transcutaneous electrical nerve stimulation could be used as analgesic adjunct. Some of the interventions, although effective, carry risks, and consequentially were omitted from the recommendations. Some interventions were not recommended due to insufficient, inconsistent or lack of evidence. Of note, these recommendations may not be applicable to unplanned deliveries or caesarean section performed under general anaesthesia.

Analgesic effect of adding magnesium sulfate to epidural levobupivacaine in patients with pre-eclampsia undergoing elective cesarean section

Background and Aims:

Magnesium is a physiological antagonist of NMDA receptor and a calcium channel blocker. This study was designed to test the analgesic effect of magnesium sulfate (MgSO₄) when added to epidural anesthesia in mild pre-eclampsia.

Material and Methods:

Sixty parturients with mild pre-eclampsia were allocated randomly to two equal groups. The Placebo group received 20 ml levobupivacaine hydrochloride 0.5% plus 5 ml isotonic saline 0.9% using two separate syringes. The Magnesium group received the same amount of local anesthetic plus 5 ml of 10% MgSO₄(500 mg) using two separate syringes. The primary outcome was pain free period. While, the secondary outcomes were the onset of motor block and the time needed to achieve complete motor block. The analgesic profile was evaluated by visual analog scale (VAS) during rest or motion, the time to first request for analgesia, and the total analgesic consumption.

Results:

The pain-free period was significantly longer in the Magnesium group (311.3 ± 21.4) compared to placebo group (153.1 ± 22.18). The total postoperative consumption of fentanyl was significantly lower in the Magnesium group (42.4 ± 5.3) than that in the placebo group (94.4 ± 9.9), with a P value 0. 01. Both the onset time of motor block and the time needed to achieve complete motor block were significantly shorter among the Magnesium group (4.4 ± 1.4 and 8.2 ± 0.4, respectively), with a P value of 0. 01.

Conclusion:

The addition of 500 mg MgSO₄ to epidural anesthesia fastens both sensory and motor blockade and improves postoperative analgesic profile.

Preoperative Assessment of the Pregnant Patient Undergoing Nonobstetric Surgery

The anesthetic management of pregnant patients can present a variety of challenges and a thorough preoperative assessment is necessary before initiating any anesthetic services. Both the mother and the fetus need to be considered when formulating an anesthetic plan and discussing informed consent. The overall aims in assessing a pregnant patient are to identity potential issues that can lead to catastrophic complications, provide adequate information allowing the mother to make informed decisions, and to obtain knowledge for tailoring an anesthetic that maintains maternal and fetal homeostasis.

Epidural Neostigmine versus Fentanyl to Decrease Bupivacaine Use in Patient-controlled Epidural Analgesia during Labor: A Randomized, Double-blind, Controlled Study

BACKGROUND

The addition of opioids to epidural local anesthetic reduces local anesthetic consumption by 20% but at the expense of side effects and time spent for regulatory compliance paperwork. Epidural neostigmine also reduces local anesthetic use. The authors hypothesized that epidural bupivacaine with neostigmine would decrease total hourly bupivacaine use compared with epidural bupivacaine with fentanyl for patient-controlled epidural analgesia.

METHODS

A total of 215 American Society of Anesthesiologists physical status II, laboring parturients requesting labor epidural analgesia consented to the study and were randomized to receive 0.125% bupivacaine with the addition of either fentanyl (2 μg/ml) or neostigmine (2, 4, or 8 μg/ml). The primary outcome was total hourly local anesthetic consumption, defined as total patient-controlled epidural analgesia use and top-ups (expressed as milliliters of 0.125% bupivacaine) divided by the infusion duration. A priori analysis determined a group size of 35 was needed to have 80% power at α = 0.05 to detect a 20% difference in the primary outcome.

RESULTS

Of 215 subjects consented, 151 patients were evaluable. Demographics, maternal and fetal outcomes, and labor characteristics were similar among groups. Total hourly local anesthetic consumption did not differ among groups (P = 0.55). The total median hourly bupivacaine consumption in the fentanyl group was 16.0 ml/h compared with 15.3, 14.6, and 16.2 ml/h in the 2, 4, and 8 μg/ml neostigmine groups, respectively (P = 0.55).

CONCLUSIONS

The data do not support any difference in bupivacaine requirements for labor patient-controlled epidural analgesia whether patients receive epidural bupivacaine with 2 to 8 μg/ml neostigmine or epidural bupivacaine with 2 μg/ml fentanyl.

Comparison of Epidural Butorphanol with Neostigmine and Epidural Sufentanyl with Neostigmine for First Stage of Labor Analgesia: A Randomized Controlled Trial

Background:

Epidural administration of neostigmine appears to be safe in the obstetric population. Recently, few studies have concluded 10 μg sufentanil to be an effective adjuvant with epidural neostigmine in providing labor analgesia. However, no study has evaluated the analgesic effect of epidural butorphanol with neostigmine for the same.

Materials and Methods:

The parturients were randomly allocated to one of the three study groups - Group A (n = 30) received butorphanol 1 mg and neostigmine 7 μg/kg. Group B (n = 30) received sufentanil 10 μg and neostigmine 7 μg/kg. Group C (n = 30) received neostigmine 7 μg/kg and 0.9% normal saline. Maternal hemodynamic parameters and fetal heart rate (FHR) were continuously monitored. The level of sensory and motor block, and visual analog scale (VAS) pain score were recorded at designated time points. In addition, the total duration of analgesia, duration of labor, mode of delivery, and any maternal or fetal adverse effects were also recorded.

Statistical Analysis Used:

A one-way analysis of variance (ANOVA) with post hoc Tukey's test was used to compare mean value among the three groups for age, height, weight, gestational age, and cervical dilatation. Repeated measure ANOVA was used to compare mean difference among the time points and also the trend among the various time points for hemodynamic parameters, VAS pain score, and FHR. For inter-group comparison among the groups, post hoc Tukey test was used.

Results:

There was a statistically significant longer effect of analgesic drug in Group B with respect to Group A and C (P < 0.001); however, the parturient in Group C had minimum duration of analgesia. Epidural neostigmine combined with sufentanil produces effective analgesia in early labor (VAS <30 within 10 min in 63.3% of parturient and within 15 min in 83.3% parturient) with average duration of 111.67 ± 24.51 min without motor block or other side effect in mother and fetus. No significant effect was observed in the duration of labor and mode of delivery in-between the two groups, and none of the patients in any group had any maternal or fetal side effects.

Conclusion:

Epidural combination of sufentanil with neostigmine provided better pain relief in terms of the total duration of analgesia and the reduction in VAS pain scores at various time points in the initial 30 min of epidural administration of drugs during the first stage of labor in parturient when compared to the epidural combination of butorphanol with neostigmine.