Effects of methylergometrine and oxytocin on thoracic epidural pressure during cesarean section

Abstract

Aim: The effects of oxytocics on thoracic epidural pressure during cesarean section were studied in 60 parturients, (American Society of Anesthesiologist physical status, class I or II) after obtaining informed consent.

Methods: The subjects were randomized to either a ergometrine (n = 30) or oxytocin treatment group (n = 30). The subjects were anesthetized with 11-12 mg of intrathecal isobaric bupivacaine (0.5%), and an epidural catheter was placed at Th 11/12, and was connected to a pressure transducer to continuously monitor thoracic epidural pressure. We analyzed epidural pressure, blood pressure, and heart rate 5 min after administering intrathecal bupivacaine (SAB5m), immediately before skin incision (pre-incision), immediately after delivery of the placenta (placenta-del), and 5 min after delivery of the fetus (CS5m).

Results: In both groups, epidural pressures were found to be elevated after delivery compared with their levels before the skin incisions were made, (P < 0.0001). Epidural pressures at placenta-del (P = 0.0055) and CS5m (P < 0.0001) were higher than at SAB5m in the ergometrine group. Epidural pressures at placenta-del were also higher than at SAB5m in the oxytocin group (P < 0.0001). Epidural pressures at placenta-del were lower in the ergometrine group compared with the oxytocin group (P = 0.0122), but epidural pressures at CS5m were higher in the ergometrine group compared with the oxytocin group (P < 0.0001).

Conclusions: We conclude that there is an increase in thoracic epidural pressure after fetal delivery, which appears to be associated with uterine contraction.