A comparison of minidose lidocaine-fentanyl spinal anesthesia and local anesthesia/propofol infusion for outpatient knee arthroscopy

Traditional methods of spinal anesthesia have proven problematic in the out patient setting. Minidose lidocaine-fentanyl spinal anesthesia (SAB(MLF)) m ay be the adaptation necessary to reestablish spinal anesthesia in this ven ue. One hundred patients scheduled for outpatient knee arthroscopy were ran domized to receive either local anesthesia plus a titrated IV propofol infu sion (LA/PI) or SAB(MLF) using 20 mg lidocaine 0.5% + 20 mug fentanyl. Pati ents received midazolam 0.02-0.03 mg/kg IV and fentanyl 0.75-1.0 mug/kg TV upon arrival in the operating room before lumbar puncture or propofol infus ion. The propofol infusion was begun at 50-75 mug . kg(-1) . min(-1) and ti trated to maintain patient comfort. Boluses (200-400 mug/kg) were given as needed. Local anesthesia included 30 mL lidocaine 1% with epinephrine 1:200 ,000 intraarticularly plus 10 mL at the portal sites. Three patients (6%) i n the LA/PI group versus none in the SAB(MLF) group required general anesth esia. Airway support was required in 54% of the LA/PI patients and in none of the SAB(MLF) patients. Total operating room time (43 vs 45 min), time to home readiness (43 vs 45 min), actual discharge times (73.3 min in both gr oups), and the incidence of discharge >90 min (22% vs 24%) were the same fo r both LA/PI and SAB(MLF) groups. LA/PI and SAB(MLF) groups differed in ter ms of postoperative pruritus (8% vs 68%), pain (44% vs 20%), nausea (8% vs 22%), and ability to void before discharge (56% vs 32%). One patient in eac h group had mild difficulty initiating voiding at home, but neither require d medical attention. In both groups, 90% of patients were either "satisfied " or "very satisfied" with their anesthetic. The two techniques provided co mparable patient satisfaction and efficiencies both intraoperatively and in postoperative recovery and discharge. The efficiencies of these techniques were not dependent on special provisions of the physical plant or the prac tice model.