Effect of uterine contractility and maternal hypotension on prolonged decelerations after bupivacaine epidural anesthesia.

Patients with prolonged decelerations after bupivacaine epidural anesthesia were matched with control patients. It was found that there were no differences in the decrease in mean arterial blood pressure after epidural anesthesia between those with prolonged decelerations (5 +/- 9 mm Hg) and those without (5 +/- 9 mm Hg). Uterine hypertonus was suggested as a cause in the prolonged deceleration group as a result of a higher rate of subjective impressions of uterine hypertonus (82% vs 11%) and more frequent use of terbutaline (30% vs 0%) after epidural anesthesia. With patients with internal uterine pressure monitors used as their own controls, it was also found that basal uterine tone was higher during periods when the deceleration occurred (26 +/- 9 mm Hg) than when it did not (13 +/- 4 mm Hg), and in comparison to windows before epidural anesthesia (12 +/- 5 mm Hg).