Anesth Analg 2003;97:397-401
© 2003 International Anesthesia Research Society
AMBULATORY ANESTHESIA
A Comparison of Two Regional Anesthetic Techniques for Outpatient Knee Arthroscopy
Julia E. Pollock, MD*,
Michael F. Mulroy, MD*,
Elyssa Bent, MD*, and
Nayak L. Polissar, PhD
*Department of Anesthesiology, Virginia-Mason Medical Center; and
The Mountain-Whisper-Light Statistical Consulting, Seattle, Washington
Address correspondence to Julia E. Pollock, MD, Department of Anesthesiology, B2-AN Virginia-Mason Medical Center, Seattle, WA 98111. Address e-mail to anejep{at}vmmc.org
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Abstract
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IMPLICATIONS: Small dose lidocaine spinal anesthesia and 3% 2-chloroprocaine epidural anesthesia provided comparable discharge times for outpatient knee arthroscopy. The incidence of transient neurologic symptoms with small-dose lidocaine spinal anesthesia was 12%.
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Introduction
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Knee arthroscopy for outpatients can safely be performed with general anesthesia, neuraxial anesthesia, or peripheral nerve blocks. Several published studies have cited varying advantages of general anesthesia with short-acting IV (1) or inhaled anesthetics (2), peripheral nerve blocks (3), local portal infiltration (4–6), and neuraxial anesthesia with lidocaine (7,8) or chloroprocaine (9,10). The ideal anesthetic for outpatient knee arthroscopy would be a technique that is easily performed, has a fast onset, and provides good surgical operating conditions with a rapid recovery and minimal side effects. This anesthetic might also provide the patient with the opportunity to view the surgical procedure. Spinal anesthesia may provide many of these advantages, but the optimum drug and dose for this technique remain undetermined.
Historically, the preferred spinal anesthetic to provide rapid discharge conditions for outpatient procedures has been hyperbaric 5% lidocaine. Case reports (11) and prospective, randomized studies (12) of the incidence of transient neurologic symptoms (TNS) after spinal anesthesia with lidocaine have led to a decreased use of spinal lidocaine among practitioners. Ben-David et al. (7) suggested that small-dose lidocaine in combination with fentanyl for spinal anesthesia might provide ideal outpatient surgical conditions with a decreased incidence of TNS. We sought to directly compare this technique to 3% 2-chloroprocaine epidural anesthesia for outpatients undergoing knee arthroscopy.
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Methods
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After IRB approval and informed consent, 63 patients scheduled for elective unilateral knee arthroscopy with or without debridement and requesting regional anesthesia were prospectively randomized to spinal or epidural anesthesia. All patients were between 21 and 60 yr of age, ASA physical status I or II, and <110 kg. Patients were English-speaking, available for follow-up phone interview, and had no contraindication to any of the anesthetic techniques (allergy, coagulopathy, infection, or neurologic disease). Patients were randomized sequentially by sealed envelope and were premedicated before block placement based on the patient’s stated preference and at the discretion of the attending anesthesiologist with a maximum of 0.03 mg/kg of midazolam (Roche, Manati, Puerto Rico) and 1 µg/kg of fentanyl (Janssen, Titusville, NJ). No patients received more than 2 mg of midazolam or 100 µg of fentanyl.
Epidural anesthesia was performed in the induction room in a standard fashion at the L2-3 or L3-4 interspace with the patient in the lateral decubitus position and the operative knee in the dependent position. Skin infiltration was performed with 1% lidocaine, and a test dose of 3 mL of 1.5% lidocaine with 15 µg of epinephrine was injected. If there was no evidence of IV or subarachnoid injection, 15 mL of 3% 2-chloroprocaine (Abbott Laboratories, North Chicago, IL) was injected in 5-mL increments, catheters were placed, and the patients were taken to the operating room. After 10 min, if the block height was below T10 (level required to provide anesthesia for thigh tourniquet discomfort), an additional 5 mL of local anesthetic was given. Spinal anesthesia was performed in the operating room at the L2-3 interspace with a 25-gauge Whitacre needle. Patients were positioned in the lateral decubitus position with the operative knee dependent. After free flow of cerebrospinal fluid, 25 mg of hyperbaric 5% lidocaine (Abbott) plus 20 µg of fentanyl (0.9-mL total volume) was injected and the patient positioned supine. Anesthesia residents or certified nurse anesthetists with an attending anesthesiologist providing medical direction (supervisory ratio, 1:2) performed all blocks.
Patients requesting sedation were given an intraoperative infusion of propofol (Gensia-Secor, Irvine, CA) at a rate of 25–50 µg · kg-1 · min-1. All patients received 30 mg IV of ketorolac (Abbott), and no patients were given antiemetic prophylaxis. Thigh tourniquets were used on all patients. The surgeon injected 50 mL of 0.25% bupivacaine into the knee joint at the completion of the procedure.
All patients were transferred by stretcher to the Phase I postanesthesia care unit (PACU). When q 5 min vital signs were stable for two measurements and block level was below T8, patients were transferred to the Phase II area. PACU discharge time was recorded as the time from admission to PACU until the patient met all discharge criteria from Phase II. These criteria included mental alertness, stable vital signs, absence of nausea, control of pain, ability to ambulate, and ability to void. Side effects measured were inadequate anesthesia, hypotension (systolic blood pressure <100 mm Hg requiring treatment with ephedrine at the discretion of the anesthesiologist), bradycardia (heart rate <50 bpm requiring treatment with atropine), nausea or vomiting, and pain requiring IV narcotics in the PACU. Specific side effects, including the presence of TNS, headache, backache, and patient satisfaction, were evaluated by follow-up phone call 24 h after the procedure. The same, blinded observer collected recovery room and follow-up data. Block levels were measured at 10-min intervals during the recovery period.
A prestudy power analysis indicated that a sample size of 18 patients per group was required to show a 30 min difference in discharge time among groups at the P < 0.05 level with 80% power. This was based on a similar study analyzing discharge characteristics of patients receiving 2-chloprocaine epidural anesthesia for knee arthroscopy performed at our institution and on previously published data using small-dose lidocaine plus fentanyl for outpatient knee arthroscopy.
For data analysis, discharge time was considered the primary outcome variable. For all outcomes, a difference between groups was considered statistically significant if P < 0.05. The secondary variable was the presence of TNS. Statistical significance of the difference among groups was based on Fisher’s exact test and the t-test.
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Results
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Sixty-three patients were randomized for this study: 33 received spinal anesthesia, and 30 had epidural anesthesia. Demographics were similar between groups (Table 1). There were no significant differences in preoperative fentanyl or midazolam administration. All operations were performed by one of three surgeons. There were no major surgical or anesthetic complications. There were 3 block failures (patients requiring laryngeal mask airway [LMA; Laryngeal Mask Co., Henley-on-Thames, UK] insertion, inhaled anesthesia, or propofol >160 µg · kg-1 · min-1) in each of the spinal anesthesia (9%) and epidural anesthesia (10%) groups. Among the six failures, three spinal anesthesia patients and two epidural anesthesia patients had detectable block levels, but the blocks were inadequate for surgery. These six patients were excluded from primary data analysis. Of the 63 patients receiving regional anesthesia, 12 patients in the epidural group and 14 patients in the spinal group requested sedation and were given a propofol infusion (average dose 25–50 µg · kg-1 · min-1) (Table 2).
The time from admission to the PACU until discharge was no different for patients receiving spinal (85 min) or epidural anesthesia (87 min) (P = 0.1; Table 3). Time to void was not significantly different among groups (P = 0.6). Between patients receiving epidural or spinal anesthesia, there were no significant differences in time from injection of local anesthetic to block resolution or until patients were ready for discharge (spinal 114 of 142 min, epidural 115 of 152 min; P = 0.9 and P = 0.2, respectively) (Table 3).
Four patients in the small-dose lidocaine spinal group reported pain radiating into their buttocks and legs and were diagnosed with TNS (12%; P = 0.1). Among the patients reporting TNS, the average verbal pain rating score (scale, 0–10) was 5.2. The average duration of TNS symptoms was 2.8 days (range, 8 h–7 days). Additionally, 13 patients in the spinal group and 18 patients in the epidural group reported nonradiating back pain. Both patient groups reported an incidence of nausea of 27% in the first 24 h after surgery. No patients vomited and none received treatment for nausea. The reported incidence of headache was 20% for epidural patients and 24% for patients receiving spinal anesthesia. No patients requested or received epidural blood patch. Patients receiving spinal anesthesia were more likely than patients receiving epidural anesthesia to report pain the evening of discharge (P = 0.03). Overall patient satisfaction was measured on a 5-point scale (5 = extremely satisfied, 4 = very satisfied, 3 = satisfied, 2 = dissatisfied, and 1 = extremely satisfied). Ninety-two percent of epidural patients and 97% of spinal patients reported being either extremely or very satisfied with their anesthetic experience (P = 0.5).
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Discussion
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We compared intraoperative conditions, discharge characteristics, and recovery profiles of small-dose lidocaine with fentanyl spinal anesthesia and 3% 2-chloprocaine epidural for outpatients undergoing knee arthroscopy. We found no significant difference in discharge times between these two regional anesthetic techniques.
Numerous investigators have sought to determine the ideal anesthetic for outpatient knee arthroscopy. As early as 1986, Patel et al. (13) determined that three-in-one femoral nerve block plus lateral femoral cutaneous nerve block compared favorably with general anesthesia or femoral nerve block alone in terms of patient comfort and discharge times. Subsequently, epidural anesthesia (10,14), local infiltration (4–6), general anesthesia with sevoflurane (2) or propofol (1), and femoral-sciatic nerve blocks (3) are all satisfactory forms of anesthesia for outpatient knee arthroscopy. Each technique has some ideal feature when measuring postoperative side effects, costs, operating room time, or efficacy.
With the current emphasis on cost reduction and decreasing discharge times, Mulroy et al. (9), Ben-David et al. (7), and Wong et al. (8) have all proposed new regional anesthetic techniques that seem to compare favorably with even the most short-acting of general anesthetics. Mulroy et al. (9) compared LMA general anesthesia with propofol-nitrous oxide to 3% 2-chloroprocaine epidural and 75 mg of subarachnoid procaine with 20 µg of fentanyl and found similar patient satisfaction and turnover times but longer recovery times in the procaine spinal group (146 minutes) when compared with both the epidural (92 minutes) and general anesthesia (104 minutes) groups.
Ben-David et al. (7) evaluated 110 patients undergoing arthroscopy in both the inpatient and outpatient setting. These patients were randomized to receive 1% hypobaric lidocaine 50 mg or 1% hypobaric lidocaine 20 mg plus 25 µg of fentanyl. This group found that the time until block regression to the S2 dermatome, time to void, and discharge times were all faster in the small-dose lidocaine plus fentanyl group. They also reported that the incidence of transient neurologic symptoms was 33% in the patients receiving 50 mg of lidocaine but only 3% in patients receiving the small-dose lidocaine plus fentanyl combination. No anesthetic failures were reported in either group.
Most recently, Wong et al. (8) reported the results of a randomization of 84 patients undergoing knee arthroscopy under spinal anesthesia with 50 mg of 1% lidocaine or LMA general anesthesia with propofol, nitrous oxide, and isoflurane. Despite similar discharge times, the patients in the spinal anesthesia group had less postoperative pain, less incidence of sore throat, and were able to eat and drink more quickly than patients in the general anesthesia group. The incidence of backache was 35% in the spinal anesthesia group.
In this study, we sought to directly compare what seem to be the most successful regional anesthetic techniques for patients undergoing knee arthroscopy as outpatients. Although we have previously determined epidural anesthesia with 3% 2-chlorprocaine to be very successful in our practice model, many anesthesiologists prefer the rapid onset and simplicity of spinal anesthesia to the delayed onset of epidural anesthesia for patients requesting regional anesthesia. Our results indicate that in terms of time to discharge, small-dose lidocaine spinal anesthesia and 3% 2-chloprocaine epidural offer similar recovery profiles. We also reported a frequent failure rate with both regional anesthesia techniques (9%–10%). The most likely reason for the failures may be related to our residency-training program and the corresponding regional anesthesia learning curve (15,16). All three patients reported having anesthesia failures in the spinal anesthesia group, and two of the three reported as having failures in the epidural group had detectable levels of spinal anesthesia before surgery. However, the level or density of the block was inadequate to perform the surgical procedure.
Our data on the failure rate and the incidence of TNS with small-dose lidocaine spinal anesthesia for outpatient patients undergoing arthroscopy differs from that previously reported by Ben-David et al (7). (Although the current incidence of 12% is less than the 18%–22% incidence we have previously reported in similar patients undergoing spinal anesthesia with 50 mg of lidocaine.) Ben-David et al.’s group found an incidence of TNS of 3% and reported no failures with the use of 20 mg of 1% hypobaric lidocaine plus 25 µg of fentanyl. In our study, we found an incidence of TNS of 12% and a failure rate of 9%–10%. There are several potential explanations for these differences. First, the patient populations were not identical. Our study focused exclusively on outpatients. In epidemiologic studies, outpatients were at increased risks for the development of TNS (17). Ben-David et al.’s group evaluated the incidence of TNS in both inpatients and outpatients, although they could detect no difference in the incidence of TNS between the two study populations. Second, the anesthetic formulations were not identical, and different volumes were used, resulting in differences in final concentration. In Ben-David et al.’s (7) study, the authors used 20 mg of 1% hypobaric lidocaine with spinal anesthesia performed in the sitting position. In our study, we evaluated 25 mg of 5% hyperbaric lidocaine with spinal anesthesia performed in the lateral position with the operative extremity dependent. Although hyperbaric and isobaric formulations have been compared and have not shown to differ in the incidence of TNS (12,18), it is possible that the additional 5 mg of lidocaine or the hyperbaric formulation could have been responsible for the increased incidence of TNS that we observed in our outpatient population. Additionally, despite the additional 5 mg of lidocaine we used in our study, we report a 10% failure rate with this technique. It is impossible to state with certainty whether this failure rate is secondary to technical failures (all the local anesthetic not being placed in the cerebrospinal fluid) or rather an inadequate dose of local anesthetic. Finally, differences between our work and that of previous authors could be due simply to inadequate sample size. Thirty patients per group would provide sufficient power to detect a difference in the incidence of TNS at a 20% occurrence rate but would be inadequate to detect a statistically significant difference if the incidence of TNS was 12%, as reported for the current study.
Despite what seems to be a frequent incidence of side effects with both techniques (27% incidence of mild nausea but no vomiting, 22% incidence of headache, and incidence of non-TNS back pain of 50%), 92% and 97% of patients in the epidural and spinal groups, respectively, reported being extremely or very satisfied with their anesthetic experience at 24-hour postanesthetic follow-up. Most of these symptoms did seem to be relatively transient because no patients requested or received treatment for nausea or requested epidural blood patch for headache.
We conclude that there are no significant differences in recovery or discharge times after 3% 2-chloroprocaine epidural anesthesia compared mini-dose lidocaine-fentanyl spinal anesthesia for outpatient knee arthroscopy. In this study, the incidence of failure with regional anesthesia was 9%–10%, and the incidence of TNS with small-dose lidocaine spinal anesthesia was 12%.
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Accepted for publication March 20, 2003.
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Abstract
Introduction
