The in-vitro effects of sevoflurane and desflurane on the contractility of pregnant human uterine muscle

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.

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.

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.

Effect of pre-exposure to sevoflurane on the bispectral index in women undergoing Caesarean delivery under general anaesthesia

BACKGROUND

Patients undergoing Caesarean delivery under inhalation anaesthesia are at a high risk of awareness, especially in the period before delivery. We assessed the effects of pre-exposure to sevoflurane on the bispectral index (BIS) in the interval before delivery.

METHODS

Sixty-four patients undergoing elective Caesarean delivery were randomly assigned to receive 1.0-1.1 vol% (control 1) or 1.2-1.3 vol% (control 2) end-tidal sevoflurane, or the same concentrations of end-tidal sevoflurane combined with pre-exposure to 1 vol% sevoflurane for the last 1 min of the preoxygenation period (the preSevo 1 and preSevo 2 groups, respectively). We assessed BIS values, arterial pressure, and heart rate at the time of induction; before intubation; and upon skin incision, uterine incision, and delivery. We also determined the maternal incidence of intraoperative awareness and the neonatal Apgar scores, and conducted umbilical blood gas analysis.

RESULTS

At skin incision, BIS values were significantly lower in the preSevo 1 group than in the control 1 group [50 (13) vs 72 (8), P<0.001] and in the preSevo 2 group than in the control 2 group [44 (11) vs 67 (10), P<0.001]. The mean BIS values in the preSevo 1 and 2 groups were maintained below 60 in the period before delivery. No other parameter differed among groups, and no patient exhibited intraoperative awareness.

CONCLUSIONS

Pre-exposure to low concentrations of sevoflurane reduced BIS values in the interval before delivery, suggesting that this approach may reduce the risk of maternal awareness. Clinical Research Information Service (code KCT0000069, http://cris.cdc.go.kr).

The effect of type of anesthesia on intra-and postoperative blood loss at elective cesarean section

BACKGROUND

In cesarean section (c-sec) it is known that women receiving spinal anesthesia have decreased intraoperative blood loss compared to women receiving general anesthesia. However, we should always consider postoperative bleeding (postpartum bleeding) that may follow. The amount of postpartum bleeding can be substantial. Therefore, we sought to evaluate the effect of type of anesthesia retrospectively on intra- and postoperative blood loss by comparing the changes of postoperative Hb, Hct at c-sec.

METHODS

We retrospectively compared the medical records of 287 elective c-sec patients. We excluded medical and obstetric conditions that may predispose such patients to increased blood loss. Subsequent detailed record analysis included 152 patients that received spinal anesthesia (group S), and 135 patients that received sevoflurane for general anesthesia (group G).

RESULTS

In comparison with the preoperative Hb, rates of Hb in the 1(st) postoperative day in group S significantly decreased compared to group G, but there was no significant difference in decreasing rates of Hb in the 3(rd) postoperative day between groups S and G. Estimated blood loss (EBL) of the intraoperative and operative day in group S was significantly lower compared to group G, but there was no significant difference in EBL of 1(st) and 2(nd) postoperative day between groups S and G.

CONCLUSIONS

We conclude that group S had a decrease in blood loss between the intraoperative and operative day and there was no significant differences in postoperative blood loss compared with group G.

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.

Inhibitory effect of alprostadil against sevoflurane-induced myometrial relaxation in rats

PURPOSE

For anesthetic management of cesarean sections, regardless of the use of regional or general anesthesia, it is crucial to achieve sufficient uterine contraction immediately following the delivery of an infant in order to reduce excessive bleeding. No previous study has investigated the ability of alprostadil, a synthesized prostaglandin, to inhibit myometrial relaxation induced by volatile anesthetics. The aim of the present study was to investigate the inhibitory effects of alprostadil on sevoflurane-induced myometrial relaxation using myometrial strips isolated from pregnant rats.

METHODS

Myometrial strips were isolated from Sprague-Dawley rats (300-400 g) in the late stage of gestation (19-21 days). The time course of changes in spontaneous myometrium contraction was studied in the presence and absence of sevoflurane. Additionally, alprostadil was titrated at three different concentrations during continuous introduction of sevoflurane 2%, and myometrium contraction was studied. As an index of contraction, the area under the contraction curve was used, and data were analyzed by repeated measure one-way analysis of variance.

RESULTS

We have shown a significant decrease in myometrium contraction as a result of the use of sevoflurane (2%). Additionally, alprostadil has been shown to inhibit myometrial relaxation induced by sevoflurane in a dose-dependent manner. The areas under the contraction curve were 87%, 87%, 129%, and 172% of the baseline value for the control and at low, medium, and high concentrations of alprostadil, respectively.

CONCLUSION

The ability of alprostadil to inhibit myometrial relaxation induced by sevoflurane suggests that the use of alprostadil during general anesthesia for cesarean section may be advantageous for the reduction of postpartum bleeding.

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.

The maternal and neonatal effects of the volatile anaesthetic agents desflurane and sevoflurane in caesarean section: a prospective, randomized clinical study

This study compared maternal and neonatal outcomes in women undergoing elective caesarean section under general anaesthesia with desflurane or sevoflurane; the neonatal effects were also compared with those in women undergoing epidural anaesthesia. Fifty women requesting general anaesthesia were randomly assigned to receive either 3% desflurane or 1% sevoflurane. Twenty-five women requesting regional anaesthesia received epidural anaesthesia with ropivacaine. Comparing desflurane sevoflurane with respect to their maternal haemodynamic effects, maternal blood pressure levels were higher and tachycardia was more frequent in the desflurane group. Comparing general and epidural anaesthesia, no significant differences were detected in terms of neonatal Apgar scores or neurological adaptive capacity scores. In conclusion, 3% desflurane or 1% sevoflurane for general anaesthesia and ropivacaine for epidural anaesthesia for elective caesarean section had similar effects on neonatal outcomes. In women who received desflurane, blood pressure and heart rate elevation were significantly higher than in the sevoflurane group, though this difference did not have any clinical importance.

Anesthésie maternofœtale pour « ex utero intrapartum » traitement (EXIT) procédure : à propos de deux cas

The ex utero intrapartum treatment (EXIT) procedure is a surgical procedure maintaining utero-placental circulation during caesarean section. Anaesthetic implications are described: foetal transplacental anaesthesia to avoid first breathing and to permit surgical procedure on obstructed foetal airway, deep maternal haemodynamically stable anaesthesia to relax uterine smooth muscle during a long caesarean procedure but avoiding post-partum haemorrhage. Volatile anaesthesia with sevoflurane seems to be adequate for these aims. Two cases are described.

Comparing the relaxing effects of desflurane and sevoflurane on oxytocin-induced contractions of isolated myometrium in both pregnant and nonpregnant rats

In this study, the effects of 2 volatile anesthetics, desflurane and sevoflurane, on oxytocin-induced contractions of isolated myometrium in pregnant and nonpregnant rats were compared. Twenty pregnant and 20 nonpregnant Wistar albino rats were studied at 19 to 20 days' gestation (term, 22 days). A total of 40 myometrial strips were obtained from pregnant and nonpregnant rats, and each of these was randomly assigned to 1 of 4 groups (n=10, each group). After spontaneous myometrial contractions were induced in the De Jalon solution, the effects of 0.5, 1, and 2 minimum alveolar anesthetic concentrations (MAC) of desflurane or sevoflurane, in the absence and presence of oxytocin (2 x 10(-9) M), were investigated. Oxytocin significantly increased the amplitude and duration of spontaneous contractions in longitudinal myometrial strips (P<.05), but not the frequency. Both agents (except for 0.5 MAC in the nonpregnant group) inhibited the duration, amplitude, and frequency of induced contractions in a dose-dependent manner. The inhibitory potencies of desflurane and sevoflurane were similar. It was found that isolated strips of pregnant rat myometrium were more sensitive to the inhibitory effects of both agents than were the nonpregnant rat myometrial strips.

Inhibitory effects of desflurane and sevoflurane on oxytocin-induced contractions of isolated pregnant human myometrium

BACKGROUND

In this study, we investigated the inhibitory effects of desflurane and sevoflurane on oxytocin-induced contractions of isolated human myometrium.

METHODS

Following delivery of the infant and placenta, a small segment of myometrium was excised from the upper incisional surface of the lower uterine segment and 20 strips, randomly assigned into two groups (n = 10), were obtained from 20 non-laboring term parturients. The study protocol consisted of a 60-min period of spontaneous contractions, control recording with oxytocin 2 x 10(9) m (10-min period), washout interval of 10 min, volatile administration (three times per 15-min period) of 0.5, 1 and 2 minimum alveolar concentration (MAC), response to oxytocin (10-min period), a further washout interval (10-min period) and subsequent control recording with oxytocin without anesthetics.

RESULTS

After oxytocin administration, the frequency and amplitude of contractions increased (P < 0.05) and the duration decreased (P < 0.05). The frequency and amplitude of contractions induced with oxytocin decreased significantly at 0.5, 1 and 2 MAC of desflurane and sevoflurane (P < 0.05). The amplitude of contractions was significantly different at 1 MAC between the two groups (P < 0.05). The duration of contractions at 2 MAC decreased in both groups (P < 0.05).

CONCLUSIONS

Desflurane and sevoflurane at 0.5, 1 and 2 MAC inhibit the frequency and amplitude of myometrial contractions induced with oxytocin in a dose-dependent manner. However, desflurane inhibits the amplitude less than sevoflurane at 1 MAC. We suggest that 0.5 MAC of both agents and 1 MAC of desflurane may be safely used in the presence of oxytocin following delivery of the infant and placenta during Cesarean section without fear of uterine atony and hemorrhage.

Four cases of the ex utero intrapartum treatment (EXIT) procedure: anesthetic implications

The ex utero intrapartum treatment (EXIT) procedure is a method of maintaining utero-placental circulation during cesarean section to gain time to secure a potentially obstructed fetal airway. Four cases of the EXIT procedure are described with special reference to the maternal anesthetic technique. Deep volatile anesthesia (approximately 2 MAC) with isoflurane or sevoflurane for a prolonged period of time, in three cases in combination with an intravenous nitroglycerin infusion, was used to ensure a fully relaxed uterus during the procedure. All mothers were maintained hemodynamically stable with preserved utero-placentary perfusion. It was possible to intubate the tracheas of two fetuses, whereas in the other two tracheostomies had to be performed. Fetal gas exchange was not negatively affected during the EXIT procedure as evidenced by normal blood gas values in the umbilical artery at the time of delivery. After reducing the concentration of volatile anesthetic, delivery of the neonate and administration of oxytocin, uterine contractility was promptly re-established and there were no signs of uterine atony in the postoperative period. All four neonates survived the procedure without complications.