RESUMEN
STUDY OBJECTIVE: To compare isobaric lidocaine and mepivacaine in outpatient arthroscopic surgery. DESIGN: Prospective, randomized, double-blinded study. SETTING: Ambulatory surgery center affiliated with an academic tertiary-care hospital. PATIENTS: 84 adult, ASA physical status 1, 2, and 3 ambulatory patients, age 18-70 years, undergoing arthroscopic knee surgery. INTERVENTION: Patients were randomized to receive a combination spinal-epidural anesthetic using 80 mg of either isobaric 2% mepivacaine or isobaric 2% lidocaine. Patients also received a femoral 3-in-1 block with 0.5% bupivacaine applied to the affected extremity. MEASUREMENTS: Demographic data and level and duration of the block were recorded. The use of supplemental epidural anesthesia was noted along with frequency of bradycardia, hypotension, and episodes of nausea and vomiting. Duration of block and times to ambulation and voiding were recorded. Delayed variables, including fatigue, difficulty urinating, back pain, and transient neurologic symptoms (TNS) were obtained. MAIN RESULTS: No demographic differences were noted between groups, and surgical duration was similar. Satisfactory anesthesia was achieved in all cases, with no differences noted in hypotension, bradycardia, nausea, or vomiting. Onset of sensory and motor block was similar. Duration of block before epidural supplementation was 94 ± 21 minutes with lidocaine versus 122 ± 23 minutes for mepivacaine (P < 0.011). Times to ambulation and voiding were longer in patients receiving mepivacaine but did not affect PACU stay. Twenty-four and 48-hour recovery was similar with no TNS symptoms reported. CONCLUSION: No major differences were noted between lidocaine and mepivacaine spinal anesthesia. Time to ambulation and voiding were longer in patients who received mepivacaine as was time to first dose of epidural catheter. Neither group had TNS symptoms. Lidocaine and mepivacaine are both appropriate spinal anesthetics for ambulatory orthopedic lower extremity procedures.