Effects of anesthetic agents on contractions of the pregnant rat myometrium in vivo and in vitro

Exploring the Utility of remimazolam in cesarean sections under general anesthesia: A preliminary retrospective analysis and Implications for future study

Background

Remimazolam has recently been introduced as a maintenance agent for general anesthesia. However, the effect of remimazolam on peripartum prognosis has not been reported. Therefore, this study aimed to compare the effects of remimazolam and propofol for uterotonic drugs following cesarean section.

Methods

The electronic medical records of 51 adult women who underwent elective cesarean sections by single obstetrician under general anesthesia were collected. Participants were categorized into two groups: the propofol group and the remimazolam group. General anesthesia was maintained by continuous infusion of propofol or remimazolam after delivery. The number of uterotonic drugs administered during the cesarean section, the estimated blood loss (EBL), and length of hospital stay (LOS) after delivery were assessed.

Results

Of the 51 patients included in the study, 35 were in the propofol group and 16 in the remimazolam group. In the remimazolam group, five patients (31.3%, 5/16) received more uterotonics than the standard regimen. Conversely, in the propofol group, 19 patients (54.3%, 19/35) were injected with more uterotonics than the standard regimen. Logistic regression analysis showed that abnormal positioning of the placenta (P = 0.079) and not using remimazolam (P = 0.100) were the most relevant factors associated with the increased use of uterotonics. There was no significant difference in EBL between the two groups. The use of remimazolam was clinically relevant with a shorter LOS (P = 0.059).

Conclusions

The use of remimazolam as a maintenance agent did not result in significantly higher use of intrapartum uterotonics compared to the use of propofol. These results cannot exclude all adverse effects of remimazolam during cesarean delivery. Further randomized controlled trials must be conducted to obtain high-quality evidence.

Comparison of the negative effect of remimazolam and propofol on cardiac contractility: Analysis of a randomised parallel-group trial and a preclinical ex vivo study

Remimazolam is a newly developed ultra-short-acting benzodiazepine that exerts sedative effects. This study aimed to clarify the effects of remimazolam on cardiac contractility. In a randomised-parallel group trial, haemodynamic parameters were compared between propofol (n = 11) and remimazolam (n = 12) groups during the induction of general anaesthesia in patients undergoing non-cardiac surgery. In a preclinical study, the direct effects of remimazolam on cardiac contractility were also evaluated using isolated rat hearts. RNA sequence data obtained from rat and human hearts were analysed to assess the expression patterns of the cardiac γ-aminobutyric acid type A (GABAA ) receptor subunits. In a clinical study, the proportional change of the maximum rate of arterial pressure rise was milder during the study period in the remimazolam group (propofol: -52.6 [10.2] (mean [standard deviation])% vs. remimazolam: -39.7% [10.5%], p = 0.007). In a preclinical study, remimazolam did not exert a negative effect on left ventricle developed pressure, whereas propofol did exert a negative effect after bolus administration of a high dose (propofol: -26.9% [3.5%] vs. remimazolam: -1.1 [6.9%], p < 0.001). Analysis of the RNA sequence revealed a lack of γ subunits, which are part of the major benzodiazepine binding site of the GABAA receptor, in rat and human hearts. These results indicate that remimazolam does not have a direct negative effect on cardiac contractility, which might contribute to its milder effect on cardiac contractility during the induction of general anaesthesia. The expression patterns of cardiac GABAA receptor subunits might be associated with the unique pharmacokinetics of benzodiazepines in the heart.

Low-dose intranasal dexmedetomidine premedication improves epidural labor analgesia onset and reduces procedural pain on epidural puncture: a prospective randomized double-blind clinical study

BACKGROUND

Epidural labor analgesia is a safe and effective method of pain management during labor with the drawbacks of delayed onset and maternal distress during epidural puncture. This study aimed to determine whether pretreatment with intranasal low-dose dexmedetomidine effectively shortens the onset of analgesia and reduces procedural pain.

METHODS

In this prospective, randomized double-blind trial, nulliparous patients were randomly assigned to either the intranasal dexmedetomidine group or the control group. The intranasal dexmedetomidine group received 0.5 μg/kg dexmedetomidine intranasally, and the control group received an equal volume of normal saline intranasally. Both groups were maintained with a programmed intermittent epidural bolus. The primary outcome was the onset time of analgesia and scores of pain related to the epidural puncture.

RESULTS

Seventy-nine patients were enrolled, and 60 completed the study and were included in the analysis. The time to achieve adequate analgesia was significantly shorter in the intranasal dexmedetomidine group than in the control group (hazard ratio = 2.069; 95% CI, 2.187 to 3.606; P = 0.010). The visual analogue scale pain scores during epidural puncture in the intranasal dexmedetomidine group were also significantly lower than those in the control group (2.0 (1.8-2.5) vs. 3.5 (3.3-4.5), P ≤ 0.001, Table 2). Pretreatment with intranasal dexmedetomidine before epidural labor analgesia was associated with improved visual analogue scale pain scores and Ramsay scores, less consumption of analgesics and higher maternal satisfaction (P < 0.05). No differences were observed for labor and neonatal outcomes or the incidence of adverse effects between the two groups.

CONCLUSIONS

Pretreatment with intranasal dexmedetomidine before epidural labor analgesia yielded a faster onset of analgesia and decreased epidural puncture pain without increasing adverse effects. Pretreatment with intranasal dexmedetomidine may be a useful adjunct for the initiation of epidural analgesia, and further investigation should be encouraged to determine its utility more fully.

TRIAL REGISTRATION

This trial was prospectively registered at Chictr.org.cn on 29/05/2020 with the registration number ChiCTR2000033356 ( http://www.chictr.org.cn/listbycreater.aspx ).

General anesthesia for cesarean section: are we doing it well?

Korea has a higher rate of cesarean sections under general anesthesia than in other countries. Neuraxial anesthesia is the gold standard for a cesarean section, but there are some cases in which general anesthesia is inevitable. Therefore, obstetric anesthesiologists should be familiar in performing general anesthesia for cesarean section. Rapid-sequence induction and intubation with cricoid pressure using thiopental-succinylcholine have been the standard for cesarean section under general anesthesia for a long time. Recently, with the introduction of new drugs (propofol, rocuronium, and sugammadex) and equipments (videolaryngoscopy and supraglottic airways), anesthesia methods have also gradually changed. Pursuing the safety of obstetric patients and anesthesiologists at the same time, this review will help update the knowledge or training in performing general anesthesia for cesarean section.

Impact of anesthetic agents on the amount of bleeding during dilatation and evacuation: A systematic review and meta-analysis

Purpose

Patients undergo dilatation and evacuation for abortion or miscarriage. However, bleeding is sometimes problematic. Despite reports on the association between volatile anesthetics and increased bleeding during the procedure, firm evidence is lacking. Therefore, we conducted a systematic review and meta-analysis to compare the effects of volatile anesthetics and propofol on the amount of bleeding in patients undergoing dilatation and evacuation.

Methods

We conducted a systematic search of four databases, namely PubMed, Embase, Cochrane Central Register of Controlled Trials databases, and Web of Science (Clarivate Analytics), from their respective inception to April 2021. Moreover, we searched two trial registration sites. The inclusion criterion was randomized controlled trials of patients who underwent dilatation and evacuation under general anesthesia using volatile anesthetics or propofol. The primary outcome was the amount of perioperative bleeding. The mean difference of the bleeding was combined using a random-effects model. The I² statistic was used to assess heterogeneity. We assessed risk of bias with Cochrane domains. We controlled type I and II errors due to sparse data and repetitive testing with Trial Sequential Analysis. We assessed the quality of evidence with GRADE.

Results

Five studies were included in the systematic review. The amount of bleeding was compared in four studies and was higher in the volatile anesthetic group, with a mean difference of 164.7 ml (95% confidence interval, 43.6 to 285.7; p = 0.04). Heterogeneity was considerable, with an I² value of 97%. Two studies evaluated the incidence of significant bleeding, which was significantly higher in the volatile anesthetic group (RR, 2.42; 95% confidence interval, 1.04–5.63; p = 0.04).

Conclusion

Choosing propofol over volatile anesthetics during dilatation and evacuation might reduce bleeding and the incidence of excessive bleeding. However, the quality of the evidence was very low. This necessitates further trials with a low risk of bias.

Trial registration

PROSPERO (CRD42019120873).

Effects of Solvents, Emulsions, Cosolvents, and Complexions on Ex Vivo Mouse Myometrial Contractility

A great need exists to develop tocolytic and uterotonic drugs that combat poor, labor-related maternal and fetal outcomes. A widely utilized method to assess novel compounds for their tocolytic and uterotonic efficacy is the isometric organ bath contractility assay. Unfortunately, water-insoluble compounds can be difficult to test using the physiological, buffer-based, organ bath assay. Common methods for overcoming solubility issues include solvent variation, cosolvency, surfactant or complexion use, and emulsification. However, these options for drug delivery or formulation can impact tissue function. Therefore, the goal of this study was to evaluate the ability of common solvents, surfactants, cosolvents, and emulsions to adequately solubilize compounds in the organ bath assay without affecting mouse myometrial contractility. We found that acetone, acetonitrile, and ethanol had the least effect, while dimethylacetamide, ethyl acetate, and isopropanol displayed the greatest inhibition of myometrial contractility based on area under the contractile curve analyses. The minimum concentration of surfactants, cosolvents, and human serum albumin required to solubilize nifedipine, a current tocolytic drug, resulted in extensive bubbling in the organ bath assay, precluding their use. Finally, we report that an oil-in-water base emulsion containing no drug has no statistical effect beyond the control (water), while the drug emulsion yielded the same potency and efficacy as the freely solubilized drug.