Effects of clonidine associated to hyperbaric bupivacaine during high-level spinal anesthesia.
OBJECTIVE
Published data suggest that clonidine, an alpha2-adrenergic agonist, in association with bupivacaine, may increase the incidence of intraoperative hypotension and bradycardia during high-level spinal anesthesia. This study aimed at determining the synergistic potential of two clonidine doses (45 and 75 microg) and hyperbaric bupivacaine on characteristics and hemodynamic effects of high-level (T4) spinal anesthesia.


METHODS
Participated in this randomized double-blind study, 60 ASA I patients scheduled for lower abdominal and limb surgery. Spinal anesthesia was induced with 17.5 mg (3.5 ml) of 0.5% hyperbaric bupivacaine plus the association of the following drugs: Control group (n = 20) - 0.5 ml isotonic saline solution; Clon 45 group (n = 20) - 45 microg (0.3 ml) clonidine + 0.2 ml isotonic saline solution; and Clon 75 (n = 20) - 75 microg (0.5 ml) clonidine. Surgery was only started when high-level (T4) analgesia was consistently obtained.


RESULTS
Sensory and motor block onset did not significantly differ among groups (p > 0.05). Both clonidine doses significantly prolonged analgesic block at T8 and motor block level 3 duration (determined by modified Bromage scale) (p < 0.05). Intraoperative arterial hypotension was observed only in Clon 75 group as compared to Control group (p < 0.05), while Clon 45 group had intermediate incidence between both groups. There was no significant difference among groups in bradycardia (p > 0.05). Both clonidine doses prolonged postoperative analgesia (time from spinal block to first postoperative analgesic request) (p < 0.05).


CONCLUSIONS
High clonidine dose (75 microg) associated to hyperbaric bupivacaine during high-level spinal anesthesia (T4) induces a higher incidence of arterial hypotension but prolongs sensory block and postoperative analgesia similar to lower clonidine dose (45 microg) during upper spinal anesthesia.
Braz
José Reinaldo Cerqueira
JR
CET/SBA, Departamento de Anestesiologia, Faculdade de Medicina de Botucatu (FMB - UNESP), Botucatu, SP. jbraz@fmb.unesp.br
Koguti
Edgar Shiguero
ES
Braz
Leandro Gobbo
LG
Croitor
Lorena Brito da Justa
LB
Navarro
Lais Helena Camacho
LH