Effects of diluent volume of a single dose of epidural bupivacaine in parturients during the first stage of labor.
OBJECTIVE
0.1% bupivacaine for obstetric epidural analgesia is given by infusion, using a loading dose of a higher concentration alone or in combination with opioid analgesics. A single dose of 0.1% without any additive for relief of first-stage labor pain has not yet been documented.


METHODS
Fifty-eight primiparae in active labor and with less than 5 cm cervical dilatation received 20 mg epidural bupivacaine diluted in 4 mL [group 1: 0.5% (I)], 10 mL [group 2: 0.2% (II)], or 20 mL [group 3: 0.1% (III)]. Pain relief, dermatomal spread, and motor block were assessed.


RESULTS
Visual analog pain scale (VAS) was significantly lower in group 2 (0.88 +/- 1.34) and group 3 (0.25 +/- 0.61) than in group 1 (4.37 +/- 2.57). Onset and time to maximum analgesia was significantly shorter in group 2 than in group 3. Mean duration of analgesia was 120 +/- 21 minutes in group 3, 100 +/- 26 in group 2, and 43 +/- 21 in group 1. The mean numbers and upper limits of dermatomes blocked did not differ between groups 2 and 3, but were higher than in group 1. Motor blocks in groups 2 and 3 were more extensive than in group 1 with no difference between groups 2 and 3. Ten mL 0.2% or 20 mL 0.1% epidural bupivacaine results in a similar degree of pain relief, superior to that following 4 mL 0.5%, while duration was longest after 20 mL 0.1%.


CONCLUSIONS
Analgesia lasts significantly longer following 20 mL 0.1% bupivacaine than following 10 mL 0.2% bupivacaine when given for first-stage labor pain. Four milliliters 0.5% bupivacaine results in inadequate pain relief.
Christiaens
F
F
Departement Anesthesie, Akademisch Ziekenhuis Vrije Universiteit Brussel, Belgium.
Verborgh
C
C
Dierick
A
A
Camu
F
F
D000328:Adult; D015360:Analgesia, Epidural / Q000379:methods*; D016362:Analgesia, Obstetrical / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage*; D002045:Bupivacaine / Q000008:administration & dosage*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007747:Labor Stage, First; D010147:Pain Measurement; D011247:Pregnancy; D011446:Prospective Studies; D012996:Solutions
D000779:Anesthetics, Local; D012996:Solutions; D002045:Bupivacaine