Continuous infusion epidural analgesia in obstetrics

Abstract

Correspondence procedure,' only 21% of mothers required no top-up, whereas in our series of longer duration, 60% of mothers required no top-up during the infusion. Any reduction in the number of top-ups will improve safety.With regard to the incidence of hypotension in our series, it can be seen that all but one of the top-up related episodes followed the initial bolus injection. We have caused misunderstanding by using the term top-up to include the initial bolus injection as well as subsequent bolus injections. Hypotension, not related to top-ups, occurred in only two patients in either Group A or B; (A, 0.08%. 8, 0.25% bupivacaine at 20 mg/hour). We do not routinely preload all our patients with an intravenous infusion of Hartmann's solution.We believe that the safest way to administer epidural analgesia in labour is by continuous pump infusion. Bupivacaine 0.08% delivered up to a maximum rate of 25 mlihour continues in our experience to be very satisfactory. In Dr Ewen's series, the 25 patients in Group A received 0.08% bupivacaine at 20 mg/hour. There were 12 hypotensive episodes in this group. Eight of these 25 patients had bilateral segmental analgesia above T,.Approximately 50% of Group A patients had severe motor weakness. Only five out of 25 deliveries were spontaneous (and seven out of the total 53 patients). Such intensity and extent of blockade is surely not necessary for analgesia of the labouring mother, and calls into question the safety of the dose regimen. It is worrying that one of the four mothers in Group A (and two out of 10 in Group B) who required Caesarean section had such profound blockade that surgery was performed without supplemental top-up. Ewen et al. have shown that increasing the volume infused extended the blockade, but at a dose rate of 20 mg/hour using 0.08% in a third of the patients the block was surely too extensive.Like Li et d.,* we have found that an infusion of 0.125% bupivacaine at 10 ml/hour is optimal. We studied 45 patients receiving such an infusion during labour, after the establishment of an epidural using 3 ml (test dose) plus 12 ml 0.25% bupivacaine plain. Eighty percent of patients required none or only one top-up of infusion for a mean infusion time of 7 hours until delivery (range 3-13.5 hours); top-up = 10 ml bolus of infusate. Twenty-five patients had good pain relief with the infusion alone for a mean infusion time of 6.5 hours until delivery (range 3-12.5 hours). There were no hypotensive episodes (blood pressure was monitored and recorded using a Datascope Accutor initially at 5-minute and then 30-minute intervals.) No patient had motor blockade intense enough to prevent them turning themselves; this is an advantage which contributes to maternal well-being and is labour-saving. Sixteen of our 45 patients had spontaneous vaginal deliveries; no patient had blockade as high as T,.The safety of such a regimen has already been stressed by Li et al. and they have shown that increasing the dose rate above this confers no additional advantage.2 In the interests...

Postoperative analgesia with epidural bupivacaine and low‐dose fentanyl ‐ a comparison of two concentrations

“…For epidural bupivacaine alone, dose has been shown to be more important than volume (12)(13)(14). It has also been reported that the infusion of a more diluted bupivacaine solution gives better analgesia than a more concentrated solution (11,15). Patients receiving the diluted solution had more motor weakness and hypotension (11).…”

“…It has also been reported that the infusion of a more diluted bupivacaine solution gives better analgesia than a more concentrated solution (11,15). Patients receiving the diluted solution had more motor weakness and hypotension (11). For a mixture of epidural bupivacaine and sufentanil used after thoracic surgery, the dose seemed more important than the volume of the solution (16), although in another study pain relief upon exercise was initially better with a low concentration/ high volume solution (17).…”

“…On the other hand, frequent changes of the reservoir increase the theoretical risk of contamination of the epidural line. The incidence of adverse effectsmotor block and hypotensionas well as analgesic effect could also depend on the concentration of the solution (2, 11).…”

Epidural bupivacaine for aortic surgery The effect of dilution on the quality of analgesia

“…The analgesia produced by such regimens is, however, often disappointing [2]. Most work on epidural infusions of local anaesthetic without added opioid has been done on parturient women, in whom it has been found that the quality of analgesia can be improved greatly by diluting the local anaesthetic and infusing a higher volume [3,4]. The purpose of this study was to determine whether this is also true in elderly high-risk patients undergoing aortic surgery.…”