A comparative evaluation of hyperbaric ropivacaine versus hyperbaric bupivacaine for elective surgery under spinal anesthesia

BACKGROUND: Recently introduced ropivacaine is 40% less potent than bupivacaine. Ropivacaine made hyperbaric by the addition of dextrose is known to provide reliable spinal anesthesia (SA). This study was designed to compare the clinical efficacy of equal doses of hyperbaric 0.5% ropivacaine with 0.5% bupivacaine for SA. MATERIALS AND METHODS: Eighty American Society of Anesthesiologists grade I-II patients undergoing elective infraumbilical surgeries under SA were recruited and randomized to receive 3ml of hyperbaric ropivacaine 5mg/ml containing dextrose 83 mg/ml (by the addition of desired dose of 25% dextrose) in Group R or 3ml of hyperbaric bupivacaine 5mg/ml containing dextrose 80 mg/ml in Group B. Monitoring of vitals and observation for the block parameters were carried out. The data were presented as mean with a standard deviation and frequency with percentage. Statistical analysis was performed using InStat computer software with appropriate tests and P < 0.05 was considered to be significant. RESULTS: Ropivacaine produced a slower onset of sensory block (ropivacaine 4.5 min; bupivacaine 3.2 min; P < 0.05) and the mean total duration of sensory block was significantly lesser (ropivacaine155 min; bupivacaine 190.5 min; P < 0.05). Patients in the ropivacaine Group R had significantly more rapid recovery from the motor blockade (ropivacaine120 min; bupivacaine 190 min; P < 0.05) and passed urine sooner than the patients in bupivacaine Group B (ropivacaine 257 min; bupivacaine 358 min; P < 0.05). CONCLUSION: Ropivacaine 15 mg in dextrose 8.3% provides reliable SA of shorter duration than bupivacaine 15 mg in 8% dextrose.