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

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.

Anesthetic management as a risk factor for postpartum hemorrhage after cesarean deliveries

OBJECTIVE

This population-based study aimed to compare the risk of postpartum hemorrhage (PPH) for patients who underwent cesarean section delivery (CS) with general vs spinal/epidural anesthesia.

STUDY DESIGN

We identified 67,328 women who had live singleton births by CS by linking the Taiwan National Health Insurance Research Dataset and the national birth certificate registry. Multivariate logistic regression was carried out to explore the relationship between anesthetic management type and PPH.

RESULTS

Women who received general anesthesia had a higher rate of PPH than women who received epidural anesthesia (5.1% vs 0.4%). The odds of PPH in women who had CS with general anesthesia were 8.15 times higher (95% confidence interval, 6.43-10.33) than for those who had CS with epidural anesthesia, after adjustment was made for the maternal and fetal characteristics.

CONCLUSION

The odds that women will experience cesarean PPH with general anesthesia are approximately 8.15 times higher than for women who undergo CS with epidural anesthesia.