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It has been suggested that use of peripheral nerve blocks (PNBs) may have some potential benefits in the outpatient setting. There have been no studies specifically comparing PNBs performed with short-acting local anesthetics with general anesthesia (GA) in patients undergoing outpatient knee surgery. We hypothesized that a combination of lumbar plexus and sciatic blocks using a short-acting local anesthetic will result in shorter time-to-discharge-home as compared with GA. Patients scheduled to undergo knee arthroscopy were randomized to receive a GA (midazolam, fentanyl, propofol, N2O/O2/desflurane via laryngeal mask airway) or lumbar plexus/sciatic block (PNBs; 2-chloroprocaine). Patients given GA also received an intraarticular injection of 20 mL 0.25% bupivacaine for postoperative pain control. Patients in the PNB group were given midazolam (up to 4 mg) and alfentanil (500750 µg) before block placement and propofol 3050 µg · kg1 · min1 for intraoperative sedation. Relevant perioperative times, postanesthesia care unit bypass rate, severity of pain, and incidence of complications were compared between the two groups. Fifty patients were enrolled in the study; 25 patients each received GA or PNBs. Total operating room time did not differ significantly between the 2 groups (97 ± 37 versus 91 ± 42 min). Seventy-two percent of patients receiving PNB met criteria enabling them to bypass Phase I postanesthesia care unit compared with only 24% of those receiving GA (P < 0.002). Time to meet criteria for discharge home (home readiness) and time to actual discharge were significantly shorter for patients given PNBs than for patients given GA (131 ± 62 versus 205 ± 94 and 162 ± 71 versus 226 ± 96, respectively). Under the conditions of our study, the combination of lumbar plexus and sciatic blocks with 2-chloroprocaine 3% was associated with a superior recovery profile compared with GA in patients having outpatient knee arthroscopy.
Knee arthroscopy is a common procedure typically performed on an outpatient basis. Various types of anesthesiaincluding local, nerve blocks, neuraxial blockade, and general anesthesia (GA)have been used successfully (14). However, there remains controversy over what constitutes the most suitable anesthetic for outpatient arthroscopic knee surgery. It has been suggested that use of peripheral nerve blocks (PNBs) or spinal anesthesia may have some potential benefits in the outpatient setting and result in less postoperative resource use, better immediate postoperative analgesia, and better patient satisfaction than GA (4). However, there have been no studies specifically comparing PNBs performed with short-acting local anesthetics with GA in patients undergoing outpatient knee surgery. We hypothesized that a combination of lumbar plexus and sciatic blocks using a short-acting local anesthetic will result in shorter time-to-discharge-home as compared with GA.
The study was approved by the IRB of St. Lukes-Roosevelt Hospital Center. Eligible patients were aged 1865 yr (n = 50), with ASA physical status IIII, and scheduled for outpatient knee arthroscopy of at least a 45-min duration. After obtaining written informed consent, patients were randomly assigned using a sealed envelope method to receive either lumbar plexus and sciatic nerve blocks or GA under standard protocols. Before anesthesia, all patients had an infusion of lactated Ringers solution started through an indwelling IV catheter. Patients were monitored during surgery and recovery according to standards/guidelines published by the American Society of Anesthesiologists.
PNBs By protocol, no other intraoperative sedatives or opioids were allowed. Patients with inadequate surgical anesthesia upon incision, or those requiring supplemental opioids, were given GA using propofol for induction, followed by placement of a laryngeal mask airway (LMA). All PNB procedures were performed by senior residents or regional anesthesia fellows under the supervision of an attending anesthesiologist with experience in regional anesthesia. At the conclusion of the procedure and after wound dressing application, the propofol infusion was stopped, and the patient was taken to a Phase I postanesthesia care unit (PACU).
GA
Recovery Home readiness and the decision to discharge were made by the Phase II PACU nursing personnel, who were unaware of the purpose of the study. Voiding was not required before discharge (6).
If patients complained of postoperative pain, medications were offered according to the following protocol. In Phase I PACU, morphine sulfate (12 mg) was administered by IV injection every 510 min until the patient was comfortable (VAS score The quantity of analgesics used during the pre-, intra-, and postoperative phases was noted. Adverse events such as nausea, vomiting, hypotension (mean arterial blood pressure <30% of preoperative), bradycardia (heart rate <60 bpm), respiratory depression (respiratory rate <10 breaths/min), hypoxia (O2 saturation <90), apnea, or dizziness were noted. Relevant time intervals, such as OR time, recovery time, and time-to-discharge-home were recorded using data from the automated record-keeping system (7). Data also were collected on the number of patients eligible to bypass Phase I PACU. Pain scores were determined using a VAS on arrival to Phase I PACU and at the time of discharge. Before discharge, patients also were asked to subjectively rate their energy levels (as self-reported on a VAS). After discharge home, a research assistant, blinded to the type of anesthetic used, collected data, via telephone interviews with the patients, on highest pain VAS scores and daily requirement for pain tablets at 24, 48, and 72 h after surgery. Data on any complications (prolonged numbness, radiating pain in the distribution of the lumbar or sciatic plexuses, motor weakness), satisfaction with anesthesia, and willingness to have the same anesthesia for their consecutive surgeries were collected 2 wk after surgery.
Sample size estimates were based on time to home readiness and discharge (in minutes), because these variables were of primary interest for this study. It was estimated that a sample size of 18 per group would provide 80% power to detect a clinically meaningful difference of 90 min (within-group standard deviation, 60 min) at
Discrete categoric data are presented as n (%); continuous data as mean ± sd. Differences in demographic, surgical, anesthetic, and postoperative data were tested by independent Students t-test (continuous data) or by
Fifty patients were enrolled (25 patients each received PNBs or GA) and successfully completed the study; there were no failed blocks or breaches in the GA protocol. There were no significant differences between the 2 groups in demographic characteristics, ASA status, and types of surgical procedures performed (Table 1).
Total OR time did not differ significantly between the 2 groups, although mean anesthetic induction time was longer (7 min) in patients given PNBs as compared with those given GA (Table 1). Patients undergoing PNB received 4.5 ± 1.5 mg of midazolam and 510 ± 240 µg of alfentanil for block induction, followed by a median dose of 189 mg (range, 0706 mg) of propofol during surgery, whereas the patients undergoing GA received 2.5 ± 1.2 mg of midazolam and 140 ± 82 µg of fentanyl intraoperatively. Seventy-two percent of patients receiving PNB met criteria enabling them to bypass Phase I PACU compared with only 24% of those receiving GA (P < 0.002). It should be noted that none of the PNBs patients met the modified Aldrete score of 10 because of the residual lower extremity blockade. Mean stay in the Phase I PACU for those who required admission was 107 ± 37 min. Mean Phase I PACU stay among these patients did not differ by type of anesthesia administered (105 ± 40 versus 115 ± 27 min for PNB and GA). Time to meet criteria for discharge home (home readiness) and time to actual discharge were significantly shorter for patients given PNBs than for patients given GA (Table 2). As expected, time to meet criteria for home readiness was significantly shorter for patients who bypassed the Phase I PACU than for those who were admitted (138 ± 80 versus 195 ± 86 min, P = 0.02); subsequently, their time to actual discharge from the hospital was also significantly shorter (168 ± 84 versus 218 ± 89 min, P < 0.05). Home readiness was significantly longer for patients who required pain medication in the Phase I PACU than for those who did not (226 versus 149 min, P = 0.006).
Four patients (16%) given PNB required pain medication upon arrival to the Phase I PACU, whereas 8 (32%) given GA required pain medication. Nausea ratings in the Phase I PACU, at discharge, and at home, were individually categorized as 0 (no nausea), 12 (mild), 35 (moderate), or 5+ (severe), and were summed into a single nausea score. Information on nausea at discharge was available for 48 patients (96%). Among these, 36 (75%) indicated that they had at least 1 episode of nausea at discharge. The occurrence of nausea was significantly associated with the type of anesthesia (Fisher exact P value = 0.03). Eleven patients with nausea (31%) had been given medication for pain in the Phase I PACU. The majority of patients given PNB (88%) reported no nausea or mild nausea (Table 2). After discharge home, most patients (70%) reported having moderate pain at 24 h postoperatively and required 37 pain tablets in the first 24 h. There was no significant difference in severity of the postoperative pain, consumption of oral analgesics, or satisfaction with anesthesia technique.
What constitutes the most suitable anesthetic for outpatient arthroscopic knee surgery remains a matter of controversy. Depending on the extent and duration of the operative procedure, the patient, and surgeon preference, knee surgery can be performed under local, spinal, epidural, nerve block, or GA (24). Postoperative pain, nausea, and vomiting can have a significant impact on the recovery process and on patient satisfaction with care after outpatient surgery (8). A recent retrospective study (9) suggests that the use of combined femoral-sciatic blocks may be associated with less postoperative pain and fewer unplanned hospital admissions in patients undergoing invasive knee surgery. Our study demonstrates that the use of PNBs in outpatients undergoing knee surgery provides several advantages over GA. Patients given PNBs had significantly less pain in the immediate postoperative period, more often bypassed the Phase I PACU, and had less postoperative nausea and vomiting than patients given GA, under the conditions of this protocol. It has been suggested that PNBs provide effective anesthesia and excellent postoperative analgesia but require more preoperative time. Some commonly voiced disadvantages of PNBs include the additional time required to perform the blocks and the potential that, although patients receiving blocks may have superior pain relief in the immediate postoperative period, they may ultimately have more pain when the blocks wear off. Neither of these assertions proved true in the current study. Although some additional time was required to perform PNBs as compared with induction of GA and securing the airway, total OR time was similar, even though the blocks were performed in the OR. This undoubtedly is attributable to the combination of our staffs experience in using PNBs for knee arthroscopy, a fast-acting local anesthetic, and the fact that surgeons could proceed with surgical preparation without having to wait to document the onset of full surgical anesthesia. Conceivably, inducing blocks preoperatively in the holding area rather than in the OR would further decrease OR time, although this may not be feasible when chloroprocaine is used as the local anesthetic because of its short duration of action. In addition, time from the end of surgical dressing until exit from the OR (emergence time) is likely faster after PNB, which would effectively offset the additional induction time needed to place the block in the OR. Our study agrees with the only two other prospective, randomized studies comparing PNBs with GA for outpatient knee arthroscopy. Patel et al. (10) found that PNBs were preferable to GA and resulted in faster home-discharge. Unfortunately, that study did not specify information about the GA technique used. Additionally, since the studys publication in 1985, there have been numerous improvements to GA techniques and introduction of the LMA, which have led to inhaled anesthetics with more favorable recovery profiles. Jankowski et al. (4), in a more-recent study, found that the use of a psoas compartment blockade decreased overall resource use (by avoiding PACU admission) and resulted in better patient satisfaction than GA did. In their study, there was no significant difference in time-to-home discharge among PNB, spinal, and GA. However, it is possible that this lack of significance was because these authors used a longer-acting local anesthetic (mepivacaine) than in our study (chloroprocaine), which precluded patients from ambulating until the PNB wore off. In addition, voiding was required in all patients in this study. Regardless, more recent data suggest that short-acting spinal anesthetics (such as chloroprocaine) might be a good choice in outpatient surgery (11). Similarly to the finding in a study by McCartney et al. (12), the analgesic benefits of PNBs in our study were limited to the immediate postoperative period. Although the choice to use a longer-acting local anesthetic in PNBs would have undoubtedly resulted in a longer duration of analgesia, we believed that the relatively minor degree of surgical trauma did not warrant the use of a long-acting local anesthetic and the consequent prolonged motor blockade of the lumbar plexus. In addition, in this study, a true multimodal approach to postoperative pain management was not used. A coadministration of oral opioids, nonsteroidal antiinflammatory drugs, and cyclooxygenase inhibitors, may have influenced the results (13). However, any beneficial effects of such therapy likely would have been conferred to both groups. Finally, it is likely that the patients in the PNB group would also have received additional analgesic benefit if they were also given the intraarticular injection of local anesthetic the GA patients received. It could be argued that a different choice of GA (e.g., total IV anesthesia) and awareness monitoring might have favorably influenced the recovery profile after GA (14,15). For instance, Ben-David et al. (16) demonstrated that both local anesthesia supplemented by a titrated IV propofol infusion and minidose lidocaine-fentanyl spinal anesthesia for outpatient knee arthroscopy provide high patient satisfaction with equally rapid recovery and discharge. However, the duration of surgery in the study by Ben-David et al. was significantly shorter than in our study (approximately 24 versus 65 minutes, respectively). This may be because our inclusion criteria (surgeries >45 minutes in duration) excluded minor interventions and short diagnostic knee arthroscopy. For that reason, their findings may not be applicable to the conditions of our study. The GA protocol used in this study in conjunction with the LMA is often accepted as a conventional model for GA in patients undergoing ambulatory surgery. For instance, a systematic analysis of the literature comparing postoperative recovery after propofol, isoflurane, desflurane, and sevoflurane-based anesthesia in adults demonstrated that early recovery was faster in the desflurane and sevoflurane groups (17). However, the incidence of nausea and vomiting were less frequent with propofol (17). Additionally, our data may not be reproducible in institutions without expertise in PNBs comparable to that of our faculty. Indeed, the training and practice of PNBs significantly varies from institution to institution and in-depth training is a prerequisite for both the success and safety of PNBs (18). Despite significant pharmacologic advances over the past decade, nausea and vomiting remain some of the most common and unpleasant experiences associated with GA in ambulatory surgery. In our study, patients having PNBs had significantly less frequent nausea and vomiting than did patients having GA (12% versus 62%), despite prophylactic administration of dolasetron in the GA group (19). It is possible, however, that administration of dolasetron as a sole prophylactic antiemetic was inadequate to prevent nausea and vomiting in the group having GA. For instance, Tang et al. (20) showed that triple antiemetic prophylaxis in patients having desflurane GA was effective in producing an equivalent uncomplicated discharge compared with a propofol GA. In addition, despite the use of a LMA, as many as 60% of the patients who received GA developed sore throat. In summary, PNBs may offer advantages over GA in outpatients having knee arthroscopy. Under the conditions of our study, patients who received PNBs had less postoperative pain and nausea in the immediate postoperative period and were able to ambulate, eat, drink, and meet home readiness criteria earlier than patients who received GA.
Financial support was provided by the Department of Anesthesiology, St. Lukes-Roosevelt Hospital Center, New York, NY. Accepted for publication November 1, 2004.
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