Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Ambulatory Anesthesia
Introduction: There are few studies that compare regional with general anesthesia (GA) in the outpatient setting. Previously, we compared epidural to general anesthesia for outpatient knee arthroscopy  and found lower incidences of nausea/vomiting and less pain, with shorter discharge times. However, newer anesthetic and analgesic agents may offer theoretical advantage for outpatient surgery, and the present study compared a propofol based general anesthetic with spinal anesthesia (SA) in patients undergoing outpatient knee arthroscopy.
Methods: With IRB approval, 61 consecutive patients undergoing ambulatory knee arthroscopy by a single surgeon were included in the study. The choice of anesthesia was randomized unless the patient expressed a specific request (N=40). All patients received midazolam 1 mg and fentanyl 50[micro sign]g in the holding area. GA was induced with propofol (3.0 +/- 2mg/kg) and maintained with propofol (120 +/- 82[micro sign]g/kg/min), N2 O, and fentanyl up to 2[micro sign]g/kg. Muscle paralysis was achieved with mivacurium. SA was achieved with 50-80mg of 5% lidocaine in equal volume CSF via a 24 gauge Sprotte needle. Subcutaneous bupivacaine 0.25% was administered into the trocar sites by the surgeon. All patients received ketorolac 30mg IV 30 minutes prior to the completion of the surgical procedure. Personnel unrelated to the study collected data regarding side effects (nausea/vomiting (N/V), pain, sore throat, backache, headache, muscle aches, dizziness, and urinary retention) and readiness to discharge times in the Post Anesthesia Care Unit (PACU) and 2nd stage outpatient recovery room (OPRR). Postoperative phone calls at 24-48 hours were conducted to assess side effects, patient satisfaction, and ambulation. Data were analyzed using the Student's t-test, the Mann-Whitney U-test and chi squared analysis. A P <0.05 was considered statistically significant.
Results: 28 patients receive GA, and 33 received SA. Demographics were similar with respect of age (47 +/- 12 y GA vs 51 +/- 14 y SA), gender (41% male GA vs 57% male SA), weight (83 +/- 15Kg GA vs 92 +/- 35Kg SA), number of patients randomized (10 GA vs 11 SA), ASA physical status (95.3% ASA I-II GA vs 87.9% ASA I-II SA) and duration of surgery (35 +/- 11 min GA vs 30 +/- 7 min SA). The incidence of nausea and pain, and the need for treatment was similar between groups (GA vs SA) in both the PACU and OPRR. No patient experienced vomiting. (Table 1)
Results of the home follow-up phone survey revealed similar incidences of pain, satisfaction with the anesthetic technique, and willingness to undergo the same anesthetic technique in the future. Differences at 24-hour follow-up included sore throat and backache. (Table 2)
Discussion: Our data demonstrate that GA, as delivered in our study, tailored to outpatients, is as well accepted and tolerated as spinal anesthesia, and offers the specific advantage of shorter discharge time from the hospital. We attribute the low incidence of nausea to the use of propofol, and the lack of reversal agents, and low pain scores to the use of ketorolac as well as the use of subcutaneously administered local anesthetic. The shorter discharge time is similarly attributed to propofol, and not needing to wait for the effects of spinal anesthesia to wear off and ambulation returning to normal.