[The effect of adding subarachnoid clonidine to hyperbaric bupivacaine and sufentanil during labor analgesia.].

BACKGROUND AND OBJECTIVES Adding subarachnoid clonidine (an alpha -agonist) prolongs the analgesic effect of the combination of sufentanil and isobaric bupivacaine when combined during labor analgesia. The aim of this study was to compare the quality and duration of the analgesia as well as the incidence of side-effects after the addition of subarachnoid clonidine to hyperbaric bupivacaine and sufentanil in a combined spinal-epidural analgesia during labor. METHODS Twenty-six patients, physical status ASA I in full-term pregnancy were studied. They randomly received the following in the subarachnoid space: clonidine, sufentanil and bupivacaine (n = 13) - referred to as the Clon/Sufenta/Bupi Group - wherein 2.5 mg of 0.5% hyperbaric bupivacaine was added to 2.5 microg of sufentanil and 30 microg of clonidine; sufentanil and bupivacaine (n = 13) - referred to as the Sufenta/Bupi Group - wherein 2.5 mg of 0.5% hyperbaric bupivacaine was added to 2.5 microg of sufentanil. This was a double-blind study. Evaluations of pain and side effects (nausea, vomiting, itching, low blood pressure and sedation) were conducted every five minutes for the first 15 minutes and after that, every 15 minutes up until the birth of the baby. Pain was evaluated using a visual analogic scale ranging from 0-10 cm (VAS 0 = absence of pain and 10 = unbearable pain). The study was over whenever complementary epidural anasthesia was found necessary (pain > 3 cm) or at the moment of birth. A Student t-test statistical analysis was performed and the results were significant (p < 0.05). RESULTS The mean pain scores at the times measured were similar for the Clon/Sufenta/Bupi and Sufenta/Bupi Groups respectively: 0 min (8.9 +/- 1.6/ 7.6 +/- 2.1), 5 min (3.4 +/- 2.3/ 2.3 +/- 3.1), 10 min (1.5 +/- 2.5/ 1.4 +/- 2.2) and 15 min (0.26 +/- 0.8/ 1.4 +/- 2.2). No differences between the Clon/Sufenta/Bupi and Sufenta/Bupi Groups, respectively, were observed regarding: the duration of the analgesia (58.8 +/- 32 min / 55.4 +/- 53 min), itching (4/13 and 4/12 patients), nausea (1/13 and 1/12 patients), vomiting (1/13 and 0/12 patients) and low blood pressure (2/13 and 1/12 patients). The sedative effect of clonidine was not observed in any patient. One patient from the Sufenta/Bupi group was eliminated from the study because the anaesthesia failed to take effect after 15 minutues. CONCLUSIONS Under the conditions observed in the study, adding a low dosage of clonidine when combined with a hyperbaric solution does not prolong the duration of the analgesia, does not improve the quality of the action and does not act as the determining factor for the occurence of low blood pressure or sedation.