Sevoflurane inhibits contraction of uterine smooth muscle from pregnant rats similarly to halothane and isoflurane

Sevoflurane and isoflurane anesthesia induce redox imbalance, but only sevoflurane impairs vascular contraction

Volatile anesthetics may cause vascular dysfunction; however, underlying effects are unclear. The aim of the present study was to investigate whether sevoflurane and isoflurane affect vascular function, nitric oxide (NO) bioavailability, and biomarkers of oxidative stress and inflammation. Wistar rats were divided into three experimental groups: Not anesthetized (control group) or submitted to anesthesia with isoflurane (Iso group) or sevoflurane (Sevo group). Hemodynamic parameters were monitored during anesthesia, and blood gas values and biochemical determinants were analyzed. Isometric contractions were recorded in aortic rings. Vasoconstriction induced by potassium chloride (KCl) and phenylephrine (Phe) were measured. No differences in hemodynamic parameters and blood gasses variables were observed. Impaired KCl and Phe-induced contractions were observed in endothelium-intact aorta of Sevo compared to Iso and Control groups. Redox imbalance was found in Sevo and Iso groups. Reduced NO bioavailability and increased activity of matrix metalloproteinase 2 (MMP-2) were observed in Sevo, but not in the Iso group. While reduced IL-10 and IL-1β were observed in Sevo, increases in IL-1β in the Iso group were found. Sevoflurane, but not isoflurane, anesthesia impairs vasocontraction, and reduced NO and cytokines and increased MMP-2 activity may be involved in vascular dysfunction after sevoflurane anesthesia.

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).

Changes in Umbilico-Placental Circulation during Prolonged Intact Cord Resuscitation in a Lamb Model

Some previous studies reported a benefit to cardiopulmonary transition at birth when starting resuscitation maneuvers while the cord was still intact for a short period of time. However, the best timing for umbilical cord clamping in this condition is unknown. The aim of this study was to explore the duration of effective umbilico-placental circulation able to promote cardiorespiratory adaptation at birth during intact cord resuscitation. Umbilico-placental blood flow and vascular resistances were measured in an experimental neonatal lamb model. After a C-section delivery, the lambs were resuscitated ventilated for 1 h while the cord was intact. The maximum and mean umbilico-placental blood flow were respectively 230 ± 75 and 160 ± 12 mL·min^-1 during the 1 h course of the experiment. However, umbilico-placental blood flow decreased and vascular resistance increased significantly 40 min after birth (p < 0.05). These results suggest that significant cardiorespiratory support can be provided by sustained placental circulation for at least 1 h during intact cord resuscitation.

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.

Factors associated with postcesarean blood transfusion: a case control study

Objective: Cesarean delivery (CD) is a known risk factor for postpartum hemorrhage. However, the characteristics associated with post-CD transfusion are not well-established. We aimed to assess blood transfusion rates and associated factors following CD.Methods: A retrospective case-control study of women who underwent CD at a university hospital. The study group comprised all women who received blood transfusion following surgery. A control group of women who did not receive postoperative blood transfusion was assigned in a two-to-one ratio.Results: During study period, the overall post-CD blood transfusion rate was 4.7%. The study group comprised 170 women, and the control group 340. Maternal age (aOR [95% CI]: 1.07 (1.03, 1.11), p = .001), parity (aOR [95% CI]: 1.26 (1.09, 1.47), p = .002), gestational hypertensive disorders (aOR [95% CI]: 4.07 (1.52, 10.91), p = .005), maternal comorbidities (aOR [95% CI]: 4.16 (1.88, 9.1), p < .001), lower predelivery hemoglobin level (aOR [95% CI]: 0.43 (0.34, 0.54), p < .001), and major placental abnormalities (aOR [95% CI]: 2.74 (1.04, 7.18), p = .04) were independently associated with blood transfusion requirement. Intrapartum characteristics associated with blood transfusion requirement included nonelective procedure (aOR [95% CI]: 3.21 (1.72, 5.99), p < .001), prolonged second stage of labor (aOR [95% CI]: 5.50 (2.57, 11.78), p < .001), longer duration of surgery (aOR [95% CI]: 1.03 (1.02, 1.04), p < .001), general anesthesia (aOR [95% CI]: 2.11 (1.14, 3.91), p = .02), and greater estimated operative blood loss (aOR [95% CI]: 5.72 (3.15, 10.36), p < .001).Conclusions: Among women who underwent CD, we identified 11 factors associated with blood transfusion following surgery. Prospective studies are warranted to assess the implementations of prophylactic interventions to reduce transfusion rates among those deemed at high risk for CD-related bleeding.

Practical application of laparoscopic oviductal artificial insemination for the propagation of domestic cats and wild felids

AI was first reported in cats almost 50 years ago but, unlike AI in other domesticated animals (e.g. dogs, cattle, horses), has not been widely used for routine propagation by veterinarians or breeders. Anatomical and physiological challenges with cats have hindered the efficiency of AI using standardised transcervical approaches applied to other species. Development of laparoscopic oviductal AI (LO-AI) has helped overcome some of these barriers and, during the past 7 years, produced high pregnancy percentages (>70%) in domestic cats using both fresh collected and frozen-thawed semen and resulted in the birth of full-term offspring in three cat hereditary disease models and six wild cat species (ocelot, Pallas's cat, fishing cat, sand cat, tiger, clouded leopard). The standard approach involves exogenous gonadotrophin treatment (typically equine chorionic gonadotrophin followed by porcine LH) to induce ovarian follicular growth and ovulation, with laparoscopic visualisation of the oviductal ostium for direct intraluminal insemination with low numbers of spermatozoa. Similar ovarian synchronisation and insemination approaches have been used with wild felids, but frequently must be refined on a species-by-species basis. From a practical perspective, LO-AI in domestic cats now has adequate efficiency for applied use as a reproductive service in veterinary practices that possess basic laparoscopy expertise.

Risk Factors for Severe Postpartum Hemorrhage After Cesarean Delivery: Case-Control Studies

BACKGROUND

Women who undergo intrapartum caesarean delivery (CD) are at increased risk of postpartum hemorrhage (PPH) compared with those undergoing prelabor CD. To determine whether the presence and strength of the associations between individual risk factors and severe PPH vary among women undergoing prelabor CD or intrapartum CD, stratified analyses are needed according to CD subtype.

METHODS

To identify risk factors for severe PPH within 2 distinct CD populations, prelabor CD and intrapartum CD, we performed 2 case-control studies. Women in each study cohort delivered at a tertiary obstetric center in the United States between 2002 and 2012. For each study, cases were women who had a blood loss ≥1500 mL or who received an intraoperative or postoperative transfusion up to 48 hours after delivery. Risk factors for severe PPH among women undergoing prelabor CD or intrapartum CD were examined in separate logistic regression models.

RESULTS

For prelabor CD, we identified 269 cases and 550 controls. Clinical factors with the highest adjusted odds for severe PPH during prelabor CD were general anesthesia (adjusted odds ratio [aOR] = 22.3; 95% confidence interval [CI], 4.9-99.9; reference group = spinal anesthesia), multiple pregnancies (aOR = 8.0; 95% CI, 4.2-15.0; reference group = singleton pregnancy), and placenta previa (aOR = 6.3; 95% CI, 3.4-11.8). For intrapartum CD, we identified 278 cases and 572 controls. Clinical factors with the highest adjusted odds for severe PPH during intrapartum CD were general anesthesia (aOR = 5.4; 95% CI, 1.7-17.1), multiple pregnancies (aOR = 3.2; 95% CI, 1.7-6.3), and a predelivery hemoglobin ≤ 9.9 g/dL (aOR = 3.0; 95% CI, 1.3-6.9; reference group = predelivery hemoglobin ≥ 11 g/dL).

CONCLUSIONS

Women who undergo prelabor CD and intrapartum CD have several shared risk factors for severe PPH (general anesthesia and multiple pregnancies). However, the risk factor profiles for severe PPH differed between these CD cohorts. Recognizing these differences may be important when planning resources and interventions for high-risk patients undergoing either prelabor or intrapartum CD.

Acute complete uterine inversion after controlled cord traction of placenta following vaginal delivery: a case report

Early recognition and active management of the third stage of labor will reduce the risks associated with uterine inversion. All staff members in the maternal unit should be updated with Green‐Top guidelines No. 52 and be appropriately trained in the PROMPT course to provide a standardized approach in obstetric emergencies.

Simultaneous cesarean delivery and craniotomy in a term pregnant patient with traumatic brain injury

The management of pregnant patients with traumatic brain injury is challenging. A multidisciplinary team approach is mandatory, and management should be individualized according to the type and extent of injury, maternal status, gestational age, and fetal status. We report a 27-year-old term primigravida presenting after head injury with Glasgow coma scale score 11 and anisocoria. Depressed temporal bone fracture and acute epidural hematoma were diagnosed, necessitating an urgent neurosurgery. Her fetus was viable with no signs of distress and no detected placental abnormalities. Cesarean delivery was performed followed by craniotomy in the same setting under general anesthesia with good outcome of the patient and her baby.

Prosocial effects of oxytocin in two mouse models of autism spectrum disorders

Clinical evidence suggests that oxytocin treatment improves social deficits and repetitive behavior in autism spectrum disorders (ASDs). However, the neuropeptide has a short plasma half-life and poor ability to penetrate the blood-brain barrier. In order to facilitate the development of more bioavailable oxytocinergic compounds as therapeutics to treat core ASD symptoms, small animal models must be validated for preclinical screens. This study examined the preclinical utility of two inbred mouse strains, BALB/cByJ and C58/J, that exhibit phenotypes relevant to core ASD symptoms. Mice from both strains were intraperitoneally administered oxytocin, using either acute or sub-chronic regimens. Acute oxytocin did not increase sociability in BALB/cByJ; however, sub-chronic oxytocin had significant prosocial effects in both BALB/cByJ and C58/J. Increased sociability was observed 24 h following the final oxytocin dose in BALB/cByJ, while prosocial effects of oxytocin emerged 1-2 weeks post-treatment in C58/J. Furthermore, acute oxytocin decreased motor stereotypy in C58/J and did not induce hypoactivity or anxiolytic-like effects in an open field test. This study demonstrates that oxytocin administration can attenuate social deficits and repetitive behavior in mouse models of ASD, dependent on dose regimen and genotype. These findings provide validation of the BALB/cByJ and C58/J models as useful platforms for screening novel drugs for intervention in ASDs and for elucidating the mechanisms contributing to the prosocial effects of oxytocin.

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.

Expression of pulmonary vasoactive factors after sevoflurane anaesthesia in rats: a quantitative real-time polymerase chain reaction study

BACKGROUND

Sevoflurane is a fluorinated volatile anaesthetic agent that lowers arterial pressure, in part by vasodilation. We previously showed, in rat lungs, that sevoflurane affected the expression of endothelin-1 (ET-1), a potent vasoconstrictor peptide. Therefore, we hypothesized that the vasodilation induced by sevoflurane involved vasodilatory and vasoconstrictor components.

METHODS

Rats were anaesthetized with sevoflurane 4% for 0, 2, and 6 h (n=9 each group) before death. In addition, a further group (n=9) were anaesthetized for 6 h then awoken for 2 h before death (n=9). We measured expression of mRNA encoding ET-1, nitric oxide synthase-1, 2, 3 (NOS1, 2, 3), haeme oxygenase-1, 2 (HO-1, 2), adrenomedullin (ADM), calcitonin gene-related peptide, vasoactive intestinal peptide, and prostacyclin synthase in whole lung using real-time reverse transcriptase-polymerase chain reaction.

RESULTS

Expressions of ET-1 and ADM were significantly increased by inhalation of sevoflurane for 2 and 6 h (P<0.05). Expression of NOS3 was significantly increased at 6 h (P<0.05). After awaking from anaesthesia, the expressions of NOS3, ET-1, and ADM returned to baseline levels.

CONCLUSIONS

Sevoflurane increased the expressions of ET-1, NOS3, and ADM. Our results suggest that the increased expressions of NOS3 and ADM may counteract that of ET-1 and so regulate pulmonary circulation under sevoflurane anaesthesia.

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.

Analgesia with sevoflurane during labour: II. Sevoflurane compared with Entonox for labour analgesia † ‡

BACKGROUND

We determined the optimal inspired sevoflurane concentration for use during labour as 0.8% in our previous study. This study compared sevoflurane at a concentration of 0.8% and Entonox((R)) (nitrous oxide 50%: oxygen 50%) for analgesia during labour in 32 healthy parturients.

METHODS

Each mother underwent two open-label, three-part sequences in random order, Entonox-sevoflurane-Entonox or sevoflurane-Entonox-sevoflurane. In each part the agent was self-administered during 10 contractions. A 100 mm visual analogue scores for pain relief and sedation was completed immediately after each contraction.

RESULTS

Two patients withdrew during administration of sevoflurane (because of its odour) and five during Entonox (requesting epidural analgesia). Of the remaining women, data were available for analysis from 29 participants: median (IQR [range]) pain relief scores were significantly higher for sevoflurane 67 (55-74 [33-100]) mm than for Entonox 51 (40-69.5 [13-100]) mm (P<0.037). Nausea and vomiting were more common in the Entonox group [relative risk 2.7 (95% CI 1.3-5.7); P=0.004]. No other adverse effects were observed in the mothers or babies. There was significantly more sedation with sevoflurane than with Entonox {74 (66.5-81 [32.5-100]) and 51 (41-69.5 [13-100]) mm, respectively; P<0.001}. Twenty-nine patients preferred sevoflurane to Entonox and found its sedative effects helpful.

CONCLUSIONS

We conclude that self-administered sevoflurane at subanaesthetic concentration (0.8%) can provide useful pain relief during the first stage of labour, and to a greater extent than Entonox. Although greater sedative effects were experienced with sevoflurane, it was preferred to Entonox.

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.

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.

Interactive effect of sevoflurane with isradipine or indomethacin on spontaneous contractile activity of isolated pregnant rat myometrium

Volatile anesthetics, calcium antagonists and non-steroidal anti-inflammatory drugs inhibit contractile activity of myometrial smooth muscle. The aim of this study was to investigate the interactive effect of sevoflurane with isradipine or indomethacin on spontaneous contractile activity of myometrial strips isolated from pregnant rats. The myometrial strips were excised from rats (250-300 g) at 19-21 days of gestation and mounted in tissue baths for recording of isometric tension. Sevoflurane (0.5 to 3 MAC) inhibited the amplitude and frequency of spontaneous myometrial contractions in a concentration-dependent manner (P<0.05). Sevoflurane responses were repeated in the presence of isradipine (a dihydropyridine-type calcium channel blocker) and indomethacin (a non-selective cyclooxygenase (COX) inhibitor). Pretreatment with isradipine (10(-6) M) or indomethacin (10(-7) M), concentrations that themselves had no effect on spontaneous contractility, significantly increased the inhibitor responses to sevoflurane on amplitude and frequency of myometrial contractions, beginning at 1 MAC (P<0.05). Blockade of calcium channels in myometrial smooth muscle may increase the inhibitor effect of sevoflurane. Further work is needed to determine the cellular mechanism(s) of this interaction.

Inhibitory effects of desflurane and sevoflurane on contractions of isolated gravid rat myometrium under oxytocin stimulation

BACKGROUND

We studied the inhibitory effects of desflurane and sevoflurane on oxytocin-induced contractions of isolated gravid rat myometrium.

METHODS

Twenty strips were obtained from rats and these were randomly assigned into two groups. The effects of desflurane and sevoflurane were evaluated by treating strips with oxytocin alone 2x10-9 M or with oxytocin after desflurane and sevoflurane at 0.5, 1, and 2 MAC.

RESULTS

Oxytocin significantly increased the amplitude and duration of contractions (P< 0.05), but it did not increase the frequency. The duration (84%, 79%), amplitude (90%, 84%) and frequency (88%, 75%) were inhibited at 2 MAC of desflurane and sevoflurane, respectively.

CONCLUSION

These results suggest that the in vitro application of desflurane and sevoflurane similarly inhibit oxytocin-induced myometrial contractions of gravid rat in a dose-dependent manner.

The direct depressant effects of desflurane and sevoflurane on spontaneous contractions of isolated gravid rat myometrium

Our purpose was to investigate the direct depressant effects of desflurane and sevoflurane at 0.5, 1 and 2 minimum alveolar concentrations (MAC) on spontaneous contractions of isolated gravid rat myometrium. Ten gravid, albino Wistar rats, weighing 240-310 g and at 19-20 days' gestation were used. Sixty myometrial strips were obtained from 10 rats, and randomly assigned into six groups of 10. After obtaining spontaneous myometrial contractions in de Jalon solution for 45 min, 0.5, 1 or 2 MAC of desflurane or sevoflurane were continuously bubbled in the bath for 15 min and myometrial contractions evaluated during the last 10 min. Desflurane 0.5 MAC did not affect duration or amplitude of spontaneous contractions, but frequency was significantly decreased (P < 0.05). Duration, amplitude and frequency were all significantly decreased by desflurane 1 and 2 MAC (P < 0.05). Sevoflurane did not affect duration, amplitude or frequency at 0.5 MAC, but amplitude and frequency were significantly decreased at 1 MAC and all were significantly decreased at 2 MAC (P < 0.05). The frequency of contractions was decreased 21.2% with 1 MAC desflurane versus 17.1% with 1 MAC sevoflurane. The amplitude and frequency of contractions were decreased 48.2% and 48.7% with 2 MAC desflurane versus 58.9% and 49.3% with 2 MAC sevoflurane, respectively. We suggest that due to tocolytic activity, desflurane and sevoflurane can be useful in non-obstetric surgery during pregnancy.

Obstetric emergencies

Obstetric hemorrhage is still a significant cause of maternal morbidity and mortality. Prevention, early recognition, and prompt intervention are the keys to minimizing complications. Resuscitation can be inadequate because of under-estimation of blood loss and misleading maternal response. A young woman may maintain a normal blood pressure until sudden and catastrophic decompensation occurs. All members of the obstetric team should know how to manage hemorrhage because timing is of the essence. Good communication with the blood bank ensures timely release of appropriate blood products. A well-coordinated team is one of the most important elements in the care of a compromised fetus. If fetal anoxia is presumed, there is less than 10 minutes to permanent fetal brain damage. Antepartum anesthesia consultation should be encouraged in parturients with medical problems.

The effects of sevoflurane on isolated gravid human myometrium

The volatile anaesthetic agents are known to influence uterine muscle tone. All of the agents studied to date have been found to produce uterine relaxation. This property has been used to produce therapeutic uterine relaxation for difficult obstetric deliveries and the Ex Utero Intrapartum Treatment (EXIT) procedure. This study describes the effects of sevoflurane on isolated human myometrium at concentrations of 0.1, 0.25, 0.5, 0.75, 1.0, 1.5, 2.5 and 3.5 MAC. Sevoflurane produces dose-dependent depression of uterine muscle contractility with an ED50 of 0.94 MAC. Frequency of contraction was increased at concentrations of 2.5 MAC and greater. At concentrations of 3.5 MAC and above, uterine activity was virtually abolished.