Prolongation de la rachianesthésie à la bupivacaïne hyperbare par l'adrénaline et la clonidine chez le vieillard

Abstract

So as to determine the effects of vasoconstriction on the duration of hyperbaric bupivacaine spinal anaesthesia, a prospective controlled study was carried out on 80 ASA class II or III patients, aged 75 years or more, who were scheduled for spinal anaesthesia for lower limb surgery. They were randomly allocated to four groups, and were each given 3 ml (15 mg) of 0.5 % bupivacaine in plain solution with 0.5 ml of 30 % dextrose solution, together with 1 ml normal saline in group I, 0.15 mg clonidine in group II, 0.2 mg adrenaline in group III, and 0.4 mg adrenaline in group IV. All patients therefore received 4.5 ml of 0.33 % bupivacaine solution in 3.3 % dextrose solution. The injection was made in the lateral position, and the patients turned supine immediately afterwards. The segmental level of sensory loss was tested using forceps. The time course required for maximal spread of the sensory blockade did not differ in the four groups. No difference was observed between median highest levels of sensory analgesia. Adding 0.15 mg clonidine or 0.4 mg adrenaline significantly prolonged mean times for two- and four-segment regression and mean times for regression to L2 level. The addition of 0.2 mg adrenaline only prolonged the mean regression time to L2 level. Regression times tended to increase more with 0.4 mg than with 0.2 mg adrenaline. Significant prolongation of motor block was also associated with the addition of vasoconstrictors. It is concluded that addition of 0.15 mg clonidine or 0.4 mg adrenaline may be useful to increase duration of hyperbaric bupivacaine spinal anaesthesia in elderly patients.