The use of lidocaine in spinal anaesthesia is associated with transient neurological syndrome (TNS). Bupivacaine has a lower incidence of TNS as an alternative but it may have a prolonged action. This study systematically reviews the literature about the recovery profile of patients undergoing spinal anaesthesia, using bupivacaine for arthroscopic knee surgery. We identified 17 eligible randomized clinical trials (RCTs) (1268 patients). All the articles in this review, except one, used hyperbaric bupivacaine. Five trials compared different doses of bupivacaine (range 3-15 mg). Large doses of bupivacaine (10 and 15 mg) were associated with delayed recovery, and supine positioning was associated with a high incidence of failure. With unilateral positioning, a dose as low as 4-5 mg seems to be sufficient. Five trials comparing bupivacaine or levobupivacaine with ropivacaine showed no significant difference in the time to home discharge. When bupivacaine was combined with fentanyl in two trials, marginal delay in recovery was found [time to discharge (min); weighted mean difference (WMD) 14.1, 95% CI 11.9-40.1] and increased nausea and pruritus but had reduced postoperative pain. Unilateral and bilateral spinal anaesthesia were assessed in two trials, and the latter group was associated with early recovery and discharge [time to discharge (min); WMD -41.6, 95% CI -63.6 to -19.6). The results of our systematic review suggest that 4-5 mg of hyperbaric bupivacaine can effectively produce spinal anaesthesia for knee arthroscopy with unilateral positioning. Ropivacaine or the addition of adjuvants did not improve the recovery time. There is a need for tighter RCTs with more consistent endpoints.

◊ Reviewed by J. Raeder, MD, PhD
Professor/Clinical director of ambulatory anaesthesia,  
Dept. of Anaesthesia, Oslo University Hospital, University of Oslo, Oslo, Norway

This article reviewed 17 trials of best quality (i.e. prospective, parallel groups, randomized, blinded) using bupivacaine for spinal anaesthesia during knee arthroscopy, published from 1950 until December 2007.

The rationale for focusing on bupivacaine is discussed. Its long-lasting effect poses potential problems but the incidence of transient nerve symptoms (TNS) is very low compared to lidocaine. The incidence of TNS with lidocaine for knee-arthroscopy has previously been reported to be particularly high, probably due to frequent movement and stretch on the gluteal and ischiadicus nerves during surgical manipulation. Still, as TNS always is a benign and transient phenomenon, it may be questioned if the total abandonment of lidocaine is warranted; the more so as TNS had hardly being raised by patients until the mid 90ies when, following some papers on TNS, patients were explicitly asked for this complication.

In the context of bupivacaine spinal anaesthesia for knee arthroscopy, it may also be prudent to discuss the valid alternative of intravenous sedation combined with local anesthesia at the knee, not carrying the problems of non-voiding, prolonged bed rest and delayed discharge. The same may be true for modern general anaesthetic techniques such as total intravenous anaesthesia with remifentanil and propofol or some inhalational supplement with sevoflurane or desflurane. As minor knee arthroscopy usually involves minor postoperative pain, the time to discharge readiness with these methods is significantly shorter than the at least 2-3 hours reported with the best bupivacaine spinal techniques.

The review included five dose-finding studies enrolling 387 patients. A supine position seems not to be recommendable, since either the dose (i.e. 5 mg) will be too low, or the dose (10-15 mg) will result in prolonged recovery beyond 4 hours. A dose of 4-5 mg seems appropriate but time to voiding and discharge readiness was at least 2 h in the best cases and on average amounted 3 h in all studies. While the patient position after administration of the block is properly addressed in the review, there is no discussion on the position of the patient during the needle insertion, is the side-down position better than sitting?.

There were four studies using fentanyl as an adjunct (and one with a morphine group), showing slightly less postoperative pain, but more frequently pruritus and on average a 14 min longer time to discharge readiness. A relevant question may be if the use of opioid resulted  in a lower dose of bupivacaine being needed, with subsequent shorter time to voiding and leg-movement. This option of dose reduction does not seem to be adressed in the cited studies. As a further comment, the pain after knee-arthroscopy is usually fairly modest, thus the use of spinal opioids in this context may be less favorable than with other more extensive and painful orthopedic procedures.

Similar results with ropivacaine and levobupivacaine as compared to bupivacaine were to be expected, although the discussion on slightly lower potency of ropivacaine may obscure the interpretation of data.