A comparative study of 0.125% racemic bupivacaine (S50-R50) and 0.125% and 0.25% 50% enantiomeric excess bupivacaine (S75-R25) in epidural anesthesia for labor analgesia.
OBJECTIVE
Continuous epidural block is used for relief of labor pain and it is associated with a low incidence of complications. Studies with the levorotatory isomer of local anesthetics demonstrated that they are safer regarding the cardiotoxicity. The objective of this study was to compare analgesia and motor blockade of 0.125% bupivacaine (S50-R50) and 0.125% and 0.25% 50% enantiomeric excess bupivacaine (S75-R25) in continuous epidural block for labor analgesia.


METHODS
Seventy-five patients in labor participated in this randomized, double-blind study after signing an informed consent. Patients were divided in three groups: GI - 0.125% bupivacaine (S50-R50); GII - 0.125% bupivacaine (S75-R25) and GIII - 0.25% bupivacaine (S75-R25).


RESULTS
The latency of analgesia, levels of sensorial blockade, volume of local anesthetic, duration of labor and analgesia, frequency of instrumental delivery, Apgar scores, or pH of umbilical cord blood showed no statistically significant differences. The length of time until the first rescue dose was greater and pain scores at 45 minutes were also greater in the 0.25% bupivacaine (S75-R25) group. The intensity of the motor blockade was greater in the 0.125% bupivacaine (S50-R50) group.


CONCLUSIONS
The motor blockade was less intense with bupivacaine (S75-R25) regardless the concentration, resulting in analgesia of better quality without interfering with the evolution of labor or the vitality of newborns.
Duarte
Nádia Maria da Conceição
NM
Instituto Materno Infantil Professor Fernando Figueira (IMIP), Recife, PE. nadia.duarte@terra.com.br
Caetano
Ana Maria Menezes
AM
Lima
Luciana Cavalcanti
LC
das Chagas
Aumério Silva
AS
D016362:Analgesia, Obstetrical; D000767:Anesthesia, Epidural; D000779:Anesthetics, Local / Q000008:administration & dosage*; D002045:Bupivacaine / Q000008:administration & dosage*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D011247:Pregnancy; D055815:Young Adult
D000779:Anesthetics, Local; D002045:Bupivacaine