The effects of sevoflurane on isolated gravid human myometrium

The use of processed electroencephalography (pEEG) in obstetric anaesthesia: a narrative review

Accidental awareness under general anaesthesia (AAGA) remains a major complication of anaesthesia. The incidence of AAGA during obstetric anaesthesia is high relative to other specialities. The use of processed electroencephalography (pEEG) in the form of "depth of anaesthesia" monitoring has been shown to reduce the incidence of AAGA in the non-obstetric population. The evidence for using pEEG to prevent AAGA in the obstetric population is poor and requires further exploration. Furthermore, pregnancy and disease states affecting the central nervous system, such as pre-eclampsia, may alter the interpretation of pEEG waveforms although this has not been fully characterised. National guidelines exist for pEEG monitoring with total intravenous anaesthesia and for "high-risk" cases regardless of technique, including the obstetric population. However, none of the currently available guidelines relates specifically to obstetric anaesthesia. Using pEEG monitoring for obstetric anaesthesia may also provide additional benefits beyond a reduction in risk of AAGA. These potential benefits include reduced postoperative nausea and vomiting, reduced anaesthetic agent use, a shorter post-anaesthetic recovery stay. In addition, pEEG acts as a surrogate marker of cerebral perfusion, and thus as an additional monitor for impending cardiovascular collapse, as seen in amniotic fluid embolism. The subtle physiological and pathological changes in EEG activity that may occur during pregnancy are an unexplored research area in the context of anaesthetic pEEG monitors. We believe that the direction of clinical practice is moving towards greater use of pEEG monitoring and individualisation of anaesthesia.

Postpartum peripheral neuropathy due to vitamin B12 deficiency, potentially precipitated by nitrous oxide use

Neurological dysfunction which would concern the anaesthetist on labour ward is typically associated with neuraxial blocks. However, an appreciation of other causes is crucial. We present a case of peripheral neuropathy secondary to vitamin B12 deficiency, which highlights the importance of a thorough neurological examination, alongside an understanding of neurological pathophysiology. This is crucial for initiating appropriate referral, subsequent investigations and treatment. Neurological dysfunction secondary to vitamin B12 deficiency may be reversible, following prolonged rehabilitation, so prevention is the best approach, which may require modification of anaesthetic techniques. In addition, at-risk patients should be screened and treated prior to nitrous oxide use, with alternative methods of labour analgesia advised in very high-risk individuals. The incidence of vitamin B12 deficiency may increase in the future potentially linked to a rise in plant-based diets, so this picture may be more commonly seen. Added vigilance by the anaesthetist is imperative.

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).

Liver and Biliary Disease of Pregnancy and Anesthetic Implications: A Review

Liver and biliary disease complicates pregnancy in varying degrees of severity to the mother and fetus, and anesthesiologists may be asked to assist in caring for these patients before, during, and after birth of the fetus. Therefore, it is important to be familiar with how different liver diseases impact the pregnancy state. In addition, knowing symptoms, signs, and laboratory markers in the context of a pregnant patient will lead to faster diagnosis and treatment of such patients. This review article discusses changes in physiology of parturients, patients with liver disease, and parturients with liver disease. Next, general treatment of parturients with acute and chronic liver dysfunction is presented. The article progresses to specific liver diseases with treatments as they relate to pregnancy. And finally, important aspects to consider when anesthetizing parturients with liver disease are discussed.

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

BACKGROUND

Several anesthetic agents are used in cesarean sections for both regional and general anesthesia purposes. However, there are no data comparing the in vivo effects of propofol, sevoflurane, and dexmedetomidine on the contraction of the myometrium in pregnant rats. The aim of this study was to investigate the effect of these anesthetic agents on myometrial contraction and elucidate the underlying mechanisms.

METHODS

Contraction force and frequency changes in response to propofol, dexmedetomidine, or sevoflurane were evaluated in vivo and in vitro. To test the effect of arachidonic acid on myometrial contraction enhanced by dexmedetomidine, changes in myometrial contraction with dexmedetomidine after administration of indomethacin were evaluated. The amount of phosphorylated myosin phosphatase target subunit 1 (MYPT1) in the membrane fraction was expressed as a percentage of the total fraction by Western blot analysis.

RESULTS

This study demonstrated that dexmedetomidine enhances oxytocin-induced contraction in the myometrium of pregnant rats, whereas propofol and sevoflurane attenuate these contractions. The dexmedetomidine-induced enhancement of myometrial contraction force was abolished by the administration of indomethacin. Propofol did not affect oxytocin-induced MYPT1 phosphorylation, whereas sevoflurane attenuated oxytocin-induced MYPT1 phosphorylation.

CONCLUSIONS

Inhibition of myofilament calcium sensitivity may underlie the inhibition of myometrial contraction induced by sevoflurane. Arachidonic acid may play an important role in the enhancement of myometrial contraction induced by dexmedetomidine by increasing myofilament calcium sensitivity. Dexmedetomidine may be used as a sedative agent to promote uterine muscle contraction and suppress bleeding after fetal delivery.

Comparison of electroencephalogram between propofol- and thiopental-induced anesthesia for awareness risk in pregnant women

There have been few comparative studies using electroencephalogram (EEG) spectral characteristics during the induction of general anesthesia for cesarean section. This retrospective study investigated the differences in the depth of anesthesia through EEG analysis between propofol- and thiopental-induced anesthesia. We reviewed data of 42 patients undergoing cesarean section who received either thiopental (5 mg/kg) or propofol (2 mg/kg). EEG data were extracted from the bispectral index (BIS) monitor, and 10-second segments were selected from the following sections: 1) Stage I, BIS below 60 after induction; 2) Stage II, after intubation completion; 3) Stage III, end-tidal sevoflurane above 0 vol%. The risk of awareness was represented by the BIS and entropy measures. In Stage III, the thiopental group (n = 20) showed significantly higher BIS value than the propofol group (n = 22) (67.9 [18.66] vs 44.5 [20.63], respectively, p = 0.002). The thiopental group had decreased slow-delta oscillations and increased beta-oscillations as compared to the propofol group in Stages II and III (p < 0.05). BIS, spectral entropy, and Renyi permutation entropy were also higher in the thiopental group at Stages II and III (p < 0.05). In conclusion, frontal spectral EEG analysis demonstrated that propofol induction maintained a deeper anesthesia than thiopental in pregnant women.

Intraoperative Blood Loss during Induced Abortion: A Comparison of Anesthetics

Objective

To determine whether there is a difference in intraoperative bleeding with inhalational versus noninhalational anesthetic agents for patients undergoing suction dilatation and curettage for first-trimester induced abortion.

Methods

This is an IRB-approved retrospective chart review of the electronic medical records of patients undergoing induced abortion at gestational ages between 5 0/7 and 14 0/7 weeks of pregnancy at the New York City Health + Hospitals/Metropolitan. The records of 138 patients who underwent suction dilatation and curettage for induced abortion between June 2012 and June 2014 were reviewed for an association between anesthetic technique and intraoperative hemorrhage. Twenty patients received inhalational anesthetic agents, while 118 received intravenous anesthetics. Blood loss was estimated by the operating gynecologists.

Results

The mean intraoperative blood loss for inhalational anesthetics (113.6 ml) was significantly higher than with noninhalational agents (40.2 ml) (p=0.007). Age, body mass index, and gestational age were not statistically different between the groups; the number of methylergonovine doses at induced abortion trended higher with inhalation anesthetics.

Conclusions

The difference in blood loss between the two types of anesthetic techniques was statistically significant. These findings may be important for patients with significant anemia or at an increased risk of bleeding, such as those with unrecognized coagulopathies.

Perioperative and transfusion outcomes in women undergoing cesarean hysterectomy for abnormal placentation

BACKGROUND

Women with placenta increta (PI) and placenta percreta (PP) are at high risk of obstetric hemorrhage; however, the severity of hemorrhage and perioperative morbidity may differ according to the degree of placental invasion. We sought to compare blood component usage and perioperative morbidity between women with PI versus PP undergoing cesarean hysterectomy (CH).

STUDY DESIGN AND METHODS

We identified 77 women who underwent CH for PI or PP from the NICHD MFMU Network Cesarean Registry, which sourced data from 19 centers from 1999 to 2002. We examined demographic, obstetric, and surgical data and rates of transfusion and perioperative morbidity. We performed statistical tests for between-group analyses; p values less than 0.05 were significant.

RESULTS

Rates of intraoperative or postoperative red blood cell (RBC) transfusion were similar between groups (PI 84% vs. PP 88%; p=0.7). We observed no between-group differences in rates of fresh-frozen plasma (FFP) transfusion (intraoperative FFP-PI 30% vs. PP 41%; p=0.3; postoperative FFP-PI 28% vs. PP 18%; p=0.4) or platelet (PLT) transfusion (intraoperative PLTs-PI 14% vs. PP 29%; p=0.2; postoperative PLTs-PI 9% vs. PP 9%; p=1.0). Among the morbidities, a higher proportion of PP women underwent cystotomy (PI 14% vs. PP 38%; p=0.02) and postoperative mechanical ventilation (PI 14% vs. PP 35%; p=0.03).

CONCLUSION

Rates of intraoperative RBC, FFP, and PLT transfusion are similar for PI and PP women, and perioperative outcomes are worse for PP women. We suggest the same mobilization transfusion medicine support for both groups, including blood ordering (type and cross-match for CH) and availability of emergency blood protocols including fibrinogen-containing preparations.

Critical care and transfusion management in maternal deaths from postpartum haemorrhage

OBJECTIVES

In postpartum haemorrhage (PPH), as for other causes of acute haemorrhage, management can have a major impact on patient outcomes. The aim of this study was to describe critical care management, particularly transfusion practices, in cases of maternal deaths from PPH.

STUDY DESIGN

This retrospective study provided a descriptive analysis of all cases of maternal death from PPH in France identified through the systematic French Confidential Enquiry into Maternal Death in 2000-2003.

RESULTS

Thirty-eight cases of maternal death from PPH were analysed. Twenty-six women (68%) had a caesarean section [21 (55%) emergency, five (13%) elective]. Uterine atony was the most common cause of PPH (n=13, 34%). Women received a median of 9 (range 2-64) units of red blood cells (RBCs) and 9 (range 2-67) units of fresh frozen plasma (FFP). The median delay in starting blood transfusion was 82 (range 0-320)min. RBC and FFP transfusions peaked 2-4h and 12-24h after PPH diagnosis, respectively. The median FFP:RBC ratio was 0.6 (range 0-2). Fibrinogen concentrates and platelets were administered to 18 (47%) and 16 (42%) women, respectively. Three women received no blood products. Coagulation tests were performed in 20 women. The haemoglobin concentration was only measured once in seven of the 22 women who survived for more than 6h. Twenty-four women received vasopressors, a central venous access was placed in 11 women, and an invasive blood pressure device was placed in two women. General anaesthesia was administered in 37 cases, with five patients being extubated during active PPH.

CONCLUSIONS

This descriptive analysis of maternal deaths from PPH suggests that there may be room for improvement of specific aspects of critical care management, including: transfusion procedures, especially administration delays and FFP:RBC ratio; repeated laboratory assessments of haemostasis and haemoglobin concentration; invasive haemodynamic monitoring; and protocols for general anaesthesia.

In Vitro Effects of Propofol on Gravid Human Myometrium

The aim of this study was to evaluate the direct effect of propofol (di-isopropyl phenol) on the contractile properties of gravid human uterine muscle.

Six specimens of uterine muscle were obtained from term parturients undergoing elective lower segment caesarean section. Small strips (1 × 2 x 12 mm) of muscle were prepared and suspended in an organ bath containing oxygenated Kreb's solution at 36.5°C. Following preparation, spontaneous regular contractions developed at a rate of one contraction every six to 10 minutes. Force of contraction was recorded continuously using an isometric tension transducer. Following baseline measurements, propofol was introduced into the bath at concentrations corresponding to 2 /μg/ml, 5 /μg/ml and 8 /μg/ml. The specimens were also exposed to intralipid in concentrations equivalent to that found in the 8 μ/ml solution of propofol to determine whether this additive influenced uterine contractility. Contractility (defined as area under the tension/time curve) was decreased to 89 ± 6.5% of control at 2 μg/ml 53±4.3% at 5 μ/ml and 45 ± 4.1% at 8 μg/ml. This decrease in contractility was statistically significant at concentrations >2 μg/ml. Intralipid did not significantly affect uterine contractility. The results of this study show that propofol decreases isolated human uterine muscle contractility in a dose-dependent manner.

Complete uterine inversion during caesarean section: A case report

Inversion of the uterus through the uterine lower segment incision during a caesarean section is an extremely rare obstetric incident. It consists, though, an emergency complication that is potentially life-threatening, especially in cases of prolonged inversion, because haemodynamic instability and shock may occur. Prompt diagnosis and immediate uterine reversion are the key actions in the management of this serious complication.

The Effects of Volatile Anesthetics on Spontaneous Contractility of Isolated Human Pregnant Uterine Muscle: A Comparison Among Sevoflurane, Desflurane, Isoflurane, and Halothane

We examined the effects of equianesthetic concentrations of sevoflurane, desflurane, isoflurane, and halothane on the spontaneous contractility of isolated human pregnant uterine muscles. We also determined if their action was related to potassium channels. Uterine specimens were obtained from normal full-term pregnant women undergoing elective lower-segment cesarean delivery. Longitudinal muscle strips were mounted vertically in tissue chambers. Their isometric tension was recorded while they were exposed to 0.5-3 minimum alveolar concentration (MAC) of volatile anesthetics in the absence and presence of the high conductance calcium-activated potassium channel blocker, tetraethylammonium, or the adenosine triphosphate-sensitive potassium channel (K(ATP))-blocker, glibenclamide. The anesthetics examined produced a dose-dependent depression of contractility. The inhibitory potency of sevoflurane and desflurane was comparable to, whereas that of isoflurane was smaller than, that of halothane: concentrations causing 50% inhibition of the contractile amplitude (ED(50)) were 1.72, 1.44, 2.35, and 1.66 MAC (P < 0.05), respectively. Tetraethylammonium and glibenclamide did not affect the uterine response to the anesthetics, except for glibenclamide, which attenuated the response to isoflurane. These results indicate that the volatile anesthetics have inhibitory effects on the contractility of the human uterus. The inhibitory effect of isoflurane may in part be mediated through activation of K(ATP) channels.

Fetal endoscopic surgery: indications and anaesthetic management

Fetal intervention for certain life-threatening conditions has progressed from being primarily experimental in nature to the standard of care in certain circumstances. While surgical techniques have advanced over the past few years, the anaesthetic goals for these interventions have remained the same; namely, minimizing maternal and fetal risk as well as maximizing the chances of a successful fetal intervention and optimize the conditions necessary to carry the fetus to term gestation. Fetal endoscopic techniques allow access to the fetus without the need for a hysterotomy incision, thus improving the chances of controlled post-operative tocolysis and term gestation after fetal intervention. This procedure, however, is not without associated risks to both fetus and mother. This chapter will address the fetal diseases that may benefit from fetoscopic intervention, the rationale behind why maternal and fetal anaesthesia is required, the various anaesthetics used for these cases and specific considerations of both maternal and fetal physiology that aid in the determination of the best anaesthetic technique for individual cases. Methods of intra-operative fetal monitoring and fetal resuscitation will also be discussed.

Airway management on placental support (AMPS)--the anaesthetic perspective

Neonatal airway obstruction has been reported to have a high mortality. Antenatal diagnosis of this condition is now possible. Anaesthetic and surgical techniques have been developed that allow neonatal airway obstruction to be managed at delivery, while the fetus remains oxygenated via the placental circulation. Three case studies are presented, and the anaesthetic issues for mother and fetus/neonate are discussed with reference to previously published cases of airway management on placental support. In particular, techniques for uterine relaxation and maintenance of placental circulation are explored. The history of these procedures and issues of planning and logistics are also discussed.