Small-dose clonidine prolongs postoperative analgesia after sciatic-femoral nerve block with 0.75% ropivacaine for foot surgery

To evaluate the effects of adding small-dose clonidine to 0.75% ropivacaine during peripheral nerve blocks, 30 ASA physical status I and II patients u ndergoing hallux valgus repair under combined sciatic-femoral nerve block w ere randomly allocated in a double-blinded fashion to receive block placeme nt with 30 mL, of either 0.75% ropivacaine atone (group Ropivacaine, n = 15 ) or 0.75% ropivacaine plus 1 mu g/kg clonidine (group Ropivacaine-Clonidin e, n = 15). Hemodynamic variables, oxygen saturation, and levels of sedatio n, as well as the time required to achieve surgical block and time to first analgesic request, were recorded by a blinded observer. Time to surgical b lockade required 10 min in both groups. Patients in the Ropivacaine-Clonidi ne group were more sedated than patients in the Ropivacaine group only 10 m in after block placement. No differences in oxygen saturation and hemodynam ic variables, degree of plain measured at first analgesic request, and cons umption of postoperative analgesics were observed between the two groups. T he mean time from block placement to first request for pain medication was shorter in group Ropivacaine (13.7 h; 25th-75th percentiles: 11.8-14.5 h) t han in group Ropivacaine-Clonidine (16.8 h; 25th-75th percentiles: 13.5-17. 8 h) (P = 0.038). We conclude that adding 1 mu g/kg clonidine to 0.75% ropi vacaine provided a 3-h delay in first request for pain medication after hal lux valgus repair, with no clinically relevant side effects.