Standard, segmental and modified segmental epidural blockade in obstetrics

Abstract

A project was carried out to compare 3 different techniques of epidural block. The project was motivated because many shortcomings were noted in the techniques in current use. These include a high incidence of hypotension after epidural block. This incidence was found to be higher than what is usually reported. The incidence and severity of hypotension was reduced by using lower dosages of Bupivacaine and by at the same time avoiding aorto-caval compression. The latter was achieved by placing the patient in the kneeling position. The quality of analgesia achieved by using Segmental blockade was inferior to that achieved by Standard Epidural blockade. On the other hand, the Modified Segmental block produced results which were statistically comparible with the Standard Block. This was not a true reflection of the clinical experience, and may indicate an inadequacy in our scoring system. Although we were unable to improve the analgesic quality by Segmental blockade, this may be merely a factor of inexperience at the present time, or due to inaccurate catheter placement. The duration of the second stage, is commonly reported to be prolonged by epidural blockade. Although we were able to shorten the second stage by using Segmental blockade, the difference was not significant. The Apgar scores of neonates born after epidural block have not been reported to be negatively influenced by epidural block. We fond a higher incidence of slightly reduced Apgar scores in the Standard and Segmental blocks, but acceptable results after Modified Segmental blockade. The Acid-base status of mothers and neonates is not known to be negatively influenced by epidural blockade. Our study confirmed this. In fact, we found that the umbilical vein p02 values to be significantly higher after the Modified Segmental block when compared with the other two techniques. Bupivacaine is to-day regarded as the best drug for epidural· block. It is however not completely without danger to mother and foetus. It is important to keep down the dosage of the drug. We used Bupivacaine with Adrenaline 1:200000. We found our blood levels to be lower than those reported in the literature. By using the Segmental blocks, the maternal blood levels were reduced significantly when compared with those of the Standard Block. Because it was reported in the literature that epidural catheters were difficult to place accurately,we performed Epidurograms to determine the fate of epidural catheters. When catheters were threaded for 10 cm or more, accurate placement was achieved in unacceptably low percentages of patients. By using the technique of Modified Epidural block, accurate catheter placement was achieved in 100% of cases. The technique of placement was safe, repeatable and reliable. It allows for a more scientific approach to epidural blockade. Foetal heart rate abnormalities are commonly associated with epidural blockade. This was confirmed by the present series - in the first 2 groups. By employing the Modified Segmental Block, we were able to reduce the incidence of foetal heart rate abnormalities to nill. This alone has made the project a worth while undertaking to us. Flaccidity of the pelvic floor, malposition of the foetal head and a high instrumental delivery rate are commonly reported after epidural block. These were confirmed by our Group A. By using the Segmental Blocks, the incidences of all these were greatly reduced. The incidence of major complications in this series was not greatly elevated above the incidence commonly reported in the literature. None of the 3 blocks tested was prone to any particular type of complication. Although the Modified Segmental block was found to have some disadvantages, these were outweighed greatly by its advantages •. We introduced two modifications into the current practice of Segmental Epidural blockade. i. We placed the top catheter at T12, after entering the epidural space in the thoracic region. ii. We placed patients in the kneeling position during epidural block. By these two modifications we hope to have made some contribution to the present status of epidural blockade. We are satisfied that this Modified Segmental Blockade has many advantages over the other techniques in use presently. We hope to do a further large study using this technique, to confirm the findings of the present (small) series.