Combined spinal-epidural anesthesia with very low dose hyperbaric levobupivacaine for cesarean section in a preeclamptic patient

Epidural volume extension: a review

Epidural volume extension is a technical modification of the combined spinal epidural block. It involves the epidural injection of normal saline or a small volume of local anaesthetic after an intrathecal injection, aiming to augment the post-spinal sensory level. Although the consequent sensory block augmentation has been adequately documented, the probable factors influencing epidural volume extension and its implications for clinical practice are not well defined. This article reviews published literature relating to the probable factors affecting epidural volume extension, its clinical implications, case reports of its successful clinical application and summarises its unexplored effects.

[Maternal hypotension with low doses of spinal bupivacaine or levobupivacaine and epidural volume expansion with saline for cesarean section]

BACKGROUND AND OBJECTIVE

Epidural volume extension (EVE) with saline solution can contribute to greater cephalad spread of drugs injected into the subarachnoid space during cesarean section. We studied the incidence of material hypotension with spinal bupivacaine or levobupivacaine (L-bupivacaine) and the spread after epidural saline injection.

MATERIAL AND METHODS

After ethics committee approval, we randomized women scheduled for cesarean section to 4 groups to receive 5 mg of 0.25% bupivacaine with (n=51) or without (n=6) saline EVE; 5 mg of 025% L-bupivacaine (n=50); or 6 mg of 03% L-bupivacaine (n=50). All patients also received 25 microg of fentanyl per 2 mL of local hyperbaric spinal anesthetic. In all except the non-EVE group, 10 mL of saline was infused through an epidural catheter 5 minutes after anesthetic infusion. We recorded patient demographic data, procedural and anesthetic times, incision-clamping times, occurrence of hypotension, ephedrine dose required, motor and sensory blockade, requirement for rescue analgesics, and neonatal outcome.

RESULTS

After 6 patients had been randomized to the non-EVE group, no further patients were assigned because all the women required rescue analgesics. Demographic data, duration of procedure, time between. incision and delivery, and Apgar scores were similar in all the groups. The incidence of hypotension was lower in the group receiving 5 mg of L-bupivacaine (26% vs. 52.9% in the bupivacaine 5-mg group, and 56% in the 6-mg L-bupivacaine group, P = .04). More women given 5 mg of L-bupivacaine required rescue analgesia (46%) than did those receiving 5 mg of bupivacaine (235%) or 6 mg of L-bupivacaine (28%) (P = .039). Hypotension was associated with a lower umbilical cord pH (P = .001). Ephedrine doses over 20 mg were also associated with a lower umbilical cord pH (P = .031).

CONCLUSIONS

The incidence of hypotension was lowest in the group anesthetized with 5 mg of L-bupivacaine, but the need for rescue analgesia was greater in this group. Doses of 5 mg and 6 mg may be sufficient for cesarean section, as they provide a good level of sensory blockade.