The aim of this prospective, randomised, blind study was to compare the evolution of spinal block produced with 50 mg lidocaine 10 mg/ml and 10 mg ropivacaine 5 mg/ml for outpatient knee arthroscopy.Methods
Thirty outpatients undergoing knee arthroscopy received 50 mg of lidocaine 10 mg/ml (n=15) or 10 mg of ropivacaine 5 mg/ml (n=15) intrathecally. The evolution of spinal block was recorded until home discharge, while the occurrence of transient neurologic symptoms (TNS) was evaluated through phone-call follow-ups.Results
The median onset time was 15 (10–21) min with lidocaine and 24 (11–37) min with ropivacaine (P=0.109). Spinal lidocaine resulted in a faster resolution of sensory block [148 (130–167) min vs. 188 (146–231) (P=0.022)], unassisted ambulation with crutches [176 (144–208) min vs. 240 (179–302) min (P=0.014)], and voiding [208 (163–254) min vs. 293 (242–343) min (P=0.001)] than ropivacaine. Recovery of motor function required 113 (95–131) min with lidocaine and 135 (87–183) with ropivacaine (P=0.219). Six lidocaine patients reported TNS (40%) as compared with no patient receiving ropivacaine (0%) (P=0.005).Conclusions
Spinal block produced with 10 mg ropivacaine 5 mg/ml is as effective as that produced by 50 mg of lidocaine 10 mg/ml. Recovery of unassisted ambulation and spontaneous voiding occurred earlier with lidocaine, but this was associated with a markedly higher incidence of TNS.