Clinical Observation On Pregnancy Affect The Efficacy Of Lumbar Epidural Anesthesia

Objective Comparing the effection of epidural anesthesia between gynecologic and obstetric operation , to explore whether pregnancy may increase the efficacy of lumbar epidural anesthesia and effect the level or range of blockade,also to evaluate whether the blocking effection of motor nerve can be improved in pregnancy under epidural anesthesia.Methods Fifty patients about to undergo cesarean section and about to undergo hysterectomy under elective lumbar epidural anesthesia with ASA physical status I orâ…¡,from 25 to 45 years old were enrolled in this study. We will randomly divide into two groups. One is pregnancy operation group, another is non-pregnancy group.Each group were 25 paitents. Patients in two groups were all premedicated with atropine 0.5 mg i.m. 30 min before admission into the operating room, After insertion of an i.v. catheter, non-invasive blood pressure, ECG and arterial oxygen saturation were monitored. All epidural punctures were performed at the L1-2 interspace. After the epidural space was identified,then 2% lidocaine 5 mL was administered as a test dose, an additional 1% ropivacaine 8 mL was injected over a 1.5-min period after local anesthetic effect and detect the level of blockade through the catheter. To detect the cephalad and caudal anesthesia level respectively , the test was conducted for 5, 10, 15, 20, and 25min following administration of lumbar epidural anesthesia,and apply the identical electric stimulation modus, and test the analgesia threshold on the right side at the dermatomes L2, S1and S3, to observe and record the Bromage score and the change of blood pressure(BP) and heart rate(HR). Results Significant differences in weight,cephalad and caudal anesthesia level were found between the two groups. There were no significant differences between the two groups in mean arterial blood pressure(MAP), but the differences were significant in heart rate(P<0.05). There were significant differences in MAP were found within each group before and 25min after epidural injection.The heart rate decreased in non-pregnancy in 25min after epidural injection. No differences in Bromage scores were found between the groups.No significant differences in pain threshold or onset of sensory blockade at the L2, S1 or S3 segments were found between the groups. The pain thresholds at the S1 and S3 dermatomes were significantly lower than that at L2 in pregnancy group. There are positive dependablity between pain threshold and time. Conclusion Comparing with non-pregnancy, pregnant women donn't enhance the sensibility of sensory and motor blockade following epidural administration of 1% ropivacaine.The pregnancy cann't improve the efficacy of motor blockade.This study t demonstrate that it is more difficult to produce rapid blockade of sacral segments,but non-pregnancy patients are more adequate than pregnancy in sacral blockade. The dose requirement for cephalad spread of lumbar epidural anesthesia is reduced in parturients. It may take over 25 min to achieve satisfactory sacral blockade with lumbar epidural anesthesia alone.