Extradural Analgesia: The Influence of Volume and Concentration of Bupivacaine on the Mode of Delivery, Analgesic Efficacy and Motor Block

Abstract

Five hundred and seventeen women in labour receiving extradural analgesia, using bupivacaine plain solution, were randomly allocated to one of three groups. Group A received 6-8ml of 0.5% solution, group B 10-14ml of 0.25% solution, and group C 6-8 ml of 0.25% solution. Spontaneous delivery occurred in 31.7% of patients in group A, 38.7% in group B and 53% in group C (P less than 0.001). The percentage of rotational forceps, ventouse and Caesarean section deliveries was similar in the three groups. Analgesia was most effective in group A, and at least in group C, both during labour and at delivery, although assessment by linear analogue score suggested that the differences between the three groups were slight. Motor block was most frequent and rapidly progressive in groups A, but was progressive in all groups, and after five or more top-up injections, was similar in the three groups. Difficulties with micturition following delivery were significantly more common in group A.

The place of 0.375% bupivacaine in obstetric anaesthesia

“…It has been implicated as the cause of increased instrumental deliveries [6], reduced maternal satisfaction [7] and long-term backache after childbirth [8]. Motor block develops earlier and is more severe when more concentrated solutions of local anaesthetics are used, and is inevitable with repeated doses of 0.375% of 0.5% bupivacaine [6].…”

Another subdural block, or was it?

“…It has been implicated as the cause of increased instrumental deliveries [6], reduced maternal satisfaction [7] and long-term backache after childbirth [8]. Motor block develops earlier and is more severe when more concentrated solutions of local anaesthetics are used, and is inevitable with repeated doses of 0.375% of 0.5% bupivacaine [6].…”

“…Slight movement of the catheter over several hours may have allowed the late aspiration of CSF, and encouraged subarachnoid spread of the subsequent doses of bupivacaine. Use of a catheter with more closely spaced eyes may have prevented this multicompartment block [6].…”

Epidural tramadol improves the quality of pain relief during labor

“…Decreased alpha and beta receptor stimulation may result in improved uteroplacental perfusion and more effective uterine activity 4 . Epidural anesthesia along with a skilled anesthetist, a faithful obstetrician and a trained midwife can convert the painful labor into a less stressful event 5 .Delivery of the infant into the arms of conscious and pain free mother is one of the most rewarding feelings in medicine 6 .…”