The Potentiation of spinal anaesthesia by co-administration of Pethidine and Ropivacaine

Abstract

Introduction. In intrathecall and epidural administration ropivacaine has proved less potent than equianalgesic doses of bupivacaine. Pethidine is the only opioid in current use that is effective for spinal anaesthesia as a sole agent or in co-administration with other local anaesthetics.
In a prospective, randomized and double-blind study the potency of spinal block produced by intrathecall administration of a mixture of 10 mg ropivacaine and 50 mg pethidine was assessed by comparing with the intrathecall administration of 15 mg ropivacaine or 15 mg bupivacaine.

Methods. After institutional approval and informed consent, 45 patients ASA grades I-II scheduled to have spinal anaesthesia for inguinal hernia repair, were randomly divided into three equal groups. Group R received 15 mg of ropivacaine, group B received 15 mg of bupivacaine and the patients in group RP received a mixture of 10 mg ropivacaine and 50 mg pethidine preservative-free. The sensory block was assessed by onset time at the L2” maximum extension of sensory blockade and time for regression to L2. The degrees of motor block were assessed by using the Bromage scale; the onset time and the duration of the block were also recorded. Haemodynamic responses, duration of postoperative analgesia and occurrence of side effects were assessed.

Results. There were no differences among the groups regarding demographic data. One patient from group R with inappropriate spinal block needed general anaesthesia and was excluded from the study. Another 4 patients from the same group complained of pain during operation. The onset and level of sensitive block did not differ significantly among the groups. The mean time for regression to L2 was significantly longer in both group B and group BP (p<0.05). The time to first reported pain was significantly longer only in group BP (p<0.001).
Regarding the motor block, there were no significant differences in the onset time and the incidence of different degrees of motor block among the three groups. The duration and intensity of motor block was significantly increased by the addition of pethidine to ropivacaine. Changes in mean arterial pressure and heart rate did not differ significantly among the groups.

Conclusions. By adding 50 mg of pethidine to 10 mg ropivacaine the potency of spinal sensory and motor block and the duration of postoperative analgesia were improved. Moreover, the haemodynamic stability was maintained without a significant increase of side effects.

Key words: spinal anaesthesia, pethidine, ropivacaine,bupivacaine

Jurnalul Român de Anestezie Terapie intensivă 2002 Vol.9 Nr.2, 106-112

Efectul de potenţare al blocului spinal prin coadministrarea subarahnoidiană de petidină şi ropivacaină