Systematic review of spinal anaesthesia using bupivacaine for ambulatory knee arthroscopy
2009; Elsevier BV; Volume: 102; Issue: 3 Linguagem: Inglês
10.1093/bja/aen389
ISSN1471-6771
AutoresGopakumar Nair, Amir Abrishami, J. Lermitte, Frances Chung,
Tópico(s)Intraoperative Neuromonitoring and Anesthetic Effects
ResumoThe 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. 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. The use of lidocaine in spinal anaesthesia has declined over the years and has become virtually nonexistent because of the high incidence of transient neurological syndrome (TNS). The abandonment of lidocaine in spinal anaesthesia, however, has been a setback for ambulatory anaesthesia, where early recovery is vital. Bupivacaine, the most common alternative to lidocaine, has a low incidence of TNS (0–1%)32Hampl KF Heinzmann-Wiedmer S Luginbuehl I et al.Transient neurologic symptoms after spinal anesthesia: a lower incidence with prilocaine and bupivacaine than with lidocaine.Anesthesiology. 1998; 88: 629-633Crossref PubMed Scopus (154) Google Scholar 33Hampl KF Schneider MC Drasner K Toxicity of spinal local anaesthetics.Curr Opin Anaesthesiol. 1999; 12: 559-564Crossref PubMed Scopus (16) Google Scholar 36Keld DB Hein L Dalgaard M Krogh L Rodt SA The incidence of transient neurologic symptoms (TNS) after spinal anaesthesia in patients undergoing surgery in the supine position. Hyperbaric lidocaine 5% versus hyperbaric bupivacaine 0.5%.Acta Anaesthesiol Scand. 2000; 44: 285-290Crossref PubMed Scopus (54) Google Scholar but delays home discharge in ambulatory surgical patients if used in the usual doses.49Pollock JE Neal JM Stephenson CA Wiley CE Prospective study of the incidence of transient radicular irritation in patients undergoing spinal anesthesia.Anesthesiology. 1996; 84: 1361-1367Crossref PubMed Scopus (275) Google Scholar Knee arthroscopy is a common procedure in the ambulatory setting. The incidence of TNS is increased with knee arthroscopy49Pollock JE Neal JM Stephenson CA Wiley CE Prospective study of the incidence of transient radicular irritation in patients undergoing spinal anesthesia.Anesthesiology. 1996; 84: 1361-1367Crossref PubMed Scopus (275) Google Scholar 53Schneider M Ettlin T Kaufmann M et al.Transient neurologic toxicity after hyperbaric subarachnoid anesthesia with 5% lidocaine.Anesth Analg. 1993; 76: 1154-1157Crossref PubMed Scopus (369) Google Scholar because of the patient positioning35Jankowski CJ Hebl JR Stuart MJ et al.A comparison of psoas compartment block and spinal and general anesthesia for outpatient knee arthroscopy.Anesth Analg. 2003; 97: 1003-1009Crossref PubMed Scopus (84) Google Scholar and ambulatory setting.26Freedman JM Li DK Drasner K Jaskela MC Larsen B Wi S Transient neurologic symptoms after spinal anesthesia: an epidemiologic study of 1,863 patients.Anesthesiology. 1998; 89: 633-641Crossref PubMed Scopus (292) Google Scholar These factors make it necessary to evaluate the role of bupivacaine as an alternative anaesthetic agent to lidocaine for spinal anaesthesia in knee arthroscopy. The aim of this systematic review is to determine the optimal dosing of bupivacaine and to investigate the effect of other strategies such as unilateral patient positioning, using alternative agents or adding adjuvants on the efficacy of the medication in this setting. This systematic review was carried out using the methods established by the Cochrane Collaboration.34Higgins JPT Green S Cochrane Handbook for Systematic Reviews of Interventions 4.2.5 [Updated May 2005]. John Wiley & Sons, Ltd, Chichester, UK2005Google Scholar We searched the Cochrane Central Register of Controlled Trials (CENTRAL) and the Database of Abstracts of Reviews of Effects (DARE) in The Cochrane Library (Issue 3, 2007) and conducted electronic searches utilizing MEDLINE from January 1950 to December 2007, EMBASE from January 1974 to December 2007, and CINAHL from January 1982 to December 2007. Both text-word and index-word terms were used; the text-word terms included in our search strategies included: ‘bupivacaine’, ‘spin$’, ‘an?esthesia’, ‘ambulatory’, ‘out?patient’, ‘day?case’, ‘surg$’, ‘knee’, ‘arthroscop$’. We also exploded the following index-word terms: ‘ambulatory surgical procedures’, ‘anesthesia, spinal’, ‘bupivacaine’, and ‘arthroscopy’. We hand-searched reference lists from the already retrieved articles to identify further trials. In addition, contact was made with the principal authors and experts in the field to identify additional published or unpublished data relevant to the review. Three reviewers (G.S.N., A.A., and J.L.) independently assessed titles, abstracts, or both of the hits retrieved from the electronic database and hand searches for possible inclusion according to the pre-defined selection criteria. Discrepancies were resolved by the fourth author (F.C.). Studies were eligible for inclusion if they were randomized clinical trials (RCTs) with parallel-group design, that evaluated the use of bupivacaine for spinal anaesthesia during elective knee arthroscopic surgery in ambulatory settings. Observational studies (e.g. non-randomized trials, case series) were not considered for review. There was no language restriction but all trials included in the review were published in English. We extracted the following information about each study: method of randomization, number and characteristics of study participants, trial design, treatment regimens, time to onset of spinal block, duration of specific positioning after placing the block, incidence of unilateral and bilateral spinal block, time to recovery, time to voiding, time to home discharge, incidence of complications and failures. Data were extracted from each trial by two reviewers (G.S.N. and A.A.), checked for consistency and accuracy, and then entered into a computer database for analysis. The authors of included trials were contacted for the missing data. Methodological quality was defined as the confidence that the design, conduct, and report restrict bias in the intervention comparison (Cochrane Handbook) as evaluated independently by the reviewers (G.S.N., A.A., and J.L.). Disagreements were resolved by the fourth author (F.C.). We assessed each study for the method of randomization, and of concealment of study intervention allocation, the degree of blinding, and the completeness of follow-up. Randomization method was considered adequate if it was generated by a table of random numbers, or computer-generated. Quasi-randomized trials (research design that does not ensure true randomization) were not included and assessed in this review. Allocation concealment was graded adequate if the allocation of patients is carried out by independent staffs who are not involved in the study, using methods such as serially numbered opaque-sealed envelopes, on-site locked computer, etc. Blinding was adequate if the patient, care givers, and outcome assessors are blinded to the treatment. Follow-up was adequate if the numbers and reasons for dropouts and withdrawals in all intervention groups are described or if it is specified that there were no dropouts or withdrawals. Statistical methods of RevMan analyses (Review Manager, version 2.4, The Nordic Cochrane Centre, Copenhagen, Denmark) were used for analysing the data. In this review, pooling of the data was possible among the results of studies comparing bupivacaine with ropivacaine and studies evaluating the role of adjuvants and different positioning. Pooled treatment effects were estimated using both fixed- and random-effect methods. However, in the text, we have reported only the fixed-effect model, as the two analyses came into a similar conclusion in the sensitivity analyses. However, with regard to the different doses of bupivacaine, the available trials have reported the outcomes in variable formats. For example, time to discharge or voiding is reported as mean (sd) in some trials and as median with range or inter-quartiles in others. This factor along with the evident clinical heterogeneity (e.g. different design) among the trials led us not to proceed to meta-analysis in this group of studies. The results of these trials, however, were reported in the review for descriptive and qualitative analyses. For continuous variables, for example, time to voiding, we calculated the weighted mean difference (WMD) with corresponding 95% confidence intervals (CIs). No dichotomous data were pooled in this systematic review. The I2 statistic was used to measure inconsistency among the study results. I2=[(Q−df)/Q]×100%, where Q is the χ2 statistic and df is its degrees of freedom (Cochrane Handbook). This describes the percentage of the variability in effect estimates that is attributable to heterogeneity rather than to sampling error (chance). A value >50% may be considered substantial heterogeneity. Subgroup analyses and assessment of publication bias (funnel plot) were not possible because of the limited number of studies used for pooling of the data. We analysed data with both fixed- and random-effect model for sensitivity analyses. The literature search performed in December 2007 identified 626 articles of potential relevance. The study selection process eliminated 437 articles by a review of the abstracts and titles. Another 117 articles were excluded after a review of their methodology and results sections. This process left us with 72 articles on spinal anaesthesia with bupivacaine for arthroscopic knee surgeries in ambulatory care (Fig. 1). The study was designed to include only randomized controlled trials. After eliminating duplicate articles (studies that are published in more than one journal or cited more than once in the same database) and non-randomized trials, only 15 articles (a total of 1248 patients)6Ben-David B Levin H Solomon E Admoni H Vaida S Spinal bupivacaine in ambulatory surgery: the effect of saline dilution.Anesth Analg. 1996; 83: 716-720Crossref PubMed Google Scholar 8Ben-David B Solomon E Levin H Admoni H Goldik Z Intrathecal fentanyl with small-dose dilute bupivacaine: better anesthesia without prolonging recovery.Anesth Analg. 1997; 85: 560-565Crossref PubMed Google Scholar 9Bigat Z Boztug N Karsli B Cete N Ertok E Comparison of hyperbaric ropivacaine and hyperbaric bupivacaine in unilateral spinal anaesthesia.Clin Drug Investig. 2006; 26: 35-41Crossref PubMed Scopus (11) Google Scholar 11Borghi B Stagni F Bugamelli S et al.Unilateral spinal block for outpatient knee arthroscopy: a dose-finding study.J Clin Anesth. 2003; 15: 351-356Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar 13Breebaart MB Vercauteren MP Hoffmann VL Adriaensen HA Urinary bladder scanning after day-case arthroscopy under spinal anaesthesia: comparison between lidocaine, ropivacaine, and levobupivacaine.Br J Anaesth. 2003; 90: 309-313Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar 16Cappelleri G Aldegheri G Danelli G et al.Spinal anesthesia with hyperbaric levobupivacaine and ropivacaine for outpatient knee arthroscopy: a prospective, randomized, double-blind study.Anesth Analg. 2005; 101: 77-82Crossref PubMed Scopus (79) Google Scholar 22El-Halafawy YM Hyperbaric spinal levobupivacaine for outpatient knee arthroscopy: a comparison to bupivacaine and ropivacaine.Egypt J Anaesth. 2008; 20: 83-89Google Scholar, 23Esmaoglu A Karaoglu S Mizrak A Boyaci A Bilateral vs. unilateral spinal anesthesia for outpatient knee arthroscopies.Knee Surg Sports Traumatol Arthrosc. 2004; 12: 155-158Crossref PubMed Scopus (33) Google Scholar, 24Fanelli G Borghi B Casati A Bertini L Montebugnoli M Torri G Unilateral bupivacaine spinal anesthesia for outpatient knee arthroscopy. Italian Study Group on Unilateral Spinal Anesthesia.Can J Anaesth. 2000; 47: 746-751Crossref PubMed Scopus (93) Google Scholar 28Gautier PE De KM Van SA et al.Intrathecal ropivacaine for ambulatory surgery.Anesthesiology. 1999; 91: 1239-1245Crossref PubMed Scopus (144) Google Scholar 31Gurkan Y Canatay H Ozdamar D Solak M Toker K Spinal anesthesia for arthroscopic knee surgery.Acta Anaesthesiol Scand. 2004; 48: 513-517Crossref PubMed Scopus (23) Google Scholar 37Kiran S Upma B Use of small-dose bupivacaine (3 mg vs 4 mg) for unilateral spinal anesthesia in the outpatient setting.Anesth Analg. 2004; 99: 302-303Crossref PubMed Scopus (9) Google Scholar 39Korhonen AM Valanne JV Jokela RM Ravaska P Korttila K Intrathecal hyperbaric bupivacaine 3 mg+fentanyl 10 microg for outpatient knee arthroscopy with tourniquet.Acta Anaesthesiol Scand. 2003; 47: 342-346Crossref PubMed Scopus (65) Google Scholar 51Roussel JR Heindel L Effects of intrathecal fentanyl on duration of bupivacaine spinal blockade for outpatient knee arthroscopy.AANA J. 1999; 67: 337-343PubMed Google Scholar 58Valanne JV Korhonen AM Jokela RM Ravaska P Korttila KK Selective spinal anesthesia: a comparison of hyperbaric bupivacaine 4 mg versus 6 mg for outpatient knee arthroscopy.Anesth Analg. 2001; 93: 1377-1379Crossref PubMed Scopus (72) Google Scholar remained. The authors of the articles with insufficient data were contacted to get more information on the data. All of the trials are included in the review and are fully referenced. The average age of the patients was 41 yr (range 18–83). The average sample size was 33 patients (range 15–50). All the articles in this review, except one,13Breebaart MB Vercauteren MP Hoffmann VL Adriaensen HA Urinary bladder scanning after day-case arthroscopy under spinal anaesthesia: comparison between lidocaine, ropivacaine, and levobupivacaine.Br J Anaesth. 2003; 90: 309-313Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar used hyperbaric bupivacaine. The RCTs were then divided into four groups. The first group was trials comparing different doses of bupivacaine,6Ben-David B Levin H Solomon E Admoni H Vaida S Spinal bupivacaine in ambulatory surgery: the effect of saline dilution.Anesth Analg. 1996; 83: 716-720Crossref PubMed Google Scholar 11Borghi B Stagni F Bugamelli S et al.Unilateral spinal block for outpatient knee arthroscopy: a dose-finding study.J Clin Anesth. 2003; 15: 351-356Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar 16Cappelleri G Aldegheri G Danelli G et al.Spinal anesthesia with hyperbaric levobupivacaine and ropivacaine for outpatient knee arthroscopy: a prospective, randomized, double-blind study.Anesth Analg. 2005; 101: 77-82Crossref PubMed Scopus (79) Google Scholar 37Kiran S Upma B Use of small-dose bupivacaine (3 mg vs 4 mg) for unilateral spinal anesthesia in the outpatient setting.Anesth Analg. 2004; 99: 302-303Crossref PubMed Scopus (9) Google Scholar 58Valanne JV Korhonen AM Jokela RM Ravaska P Korttila KK Selective spinal anesthesia: a comparison of hyperbaric bupivacaine 4 mg versus 6 mg for outpatient knee arthroscopy.Anesth Analg. 2001; 93: 1377-1379Crossref PubMed Scopus (72) Google Scholar the second group those comparing the effects of adding adjuvants,8Ben-David B Solomon E Levin H Admoni H Goldik Z Intrathecal fentanyl with small-dose dilute bupivacaine: better anesthesia without prolonging recovery.Anesth Analg. 1997; 85: 560-565Crossref PubMed Google Scholar 31Gurkan Y Canatay H Ozdamar D Solak M Toker K Spinal anesthesia for arthroscopic knee surgery.Acta Anaesthesiol Scand. 2004; 48: 513-517Crossref PubMed Scopus (23) Google Scholar 39Korhonen AM Valanne JV Jokela RM Ravaska P Korttila K Intrathecal hyperbaric bupivacaine 3 mg+fentanyl 10 microg for outpatient knee arthroscopy with tourniquet.Acta Anaesthesiol Scand. 2003; 47: 342-346Crossref PubMed Scopus (65) Google Scholar 51Roussel JR Heindel L Effects of intrathecal fentanyl on duration of bupivacaine spinal blockade for outpatient knee arthroscopy.AANA J. 1999; 67: 337-343PubMed Google Scholar the third group those comparing bupivacaine with ropivacaine,9Bigat Z Boztug N Karsli B Cete N Ertok E Comparison of hyperbaric ropivacaine and hyperbaric bupivacaine in unilateral spinal anaesthesia.Clin Drug Investig. 2006; 26: 35-41Crossref PubMed Scopus (11) Google Scholar 13Breebaart MB Vercauteren MP Hoffmann VL Adriaensen HA Urinary bladder scanning after day-case arthroscopy under spinal anaesthesia: comparison between lidocaine, ropivacaine, and levobupivacaine.Br J Anaesth. 2003; 90: 309-313Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar 16Cappelleri G Aldegheri G Danelli G et al.Spinal anesthesia with hyperbaric levobupivacaine and ropivacaine for outpatient knee arthroscopy: a prospective, randomized, double-blind study.Anesth Analg. 2005; 101: 77-82Crossref PubMed Scopus (79) Google Scholar 22El-Halafawy YM Hyperbaric spinal levobupivacaine for outpatient knee arthroscopy: a comparison to bupivacaine and ropivacaine.Egypt J Anaesth. 2008; 20: 83-89Google Scholar 28Gautier PE De KM Van SA et al.Intrathecal ropivacaine for ambulatory surgery.Anesthesiology. 1999; 91: 1239-1245Crossref PubMed Scopus (144) Google Scholar and the fourth group comparing different patient positions after administering spinal anaesthesia.23Esmaoglu A Karaoglu S Mizrak A Boyaci A Bilateral vs. unilateral spinal anesthesia for outpatient knee arthroscopies.Knee Surg Sports Traumatol Arthrosc. 2004; 12: 155-158Crossref PubMed Scopus (33) Google Scholar 24Fanelli G Borghi B Casati A Bertini L Montebugnoli M Torri G Unilateral bupivacaine spinal anesthesia for outpatient knee arthroscopy. Italian Study Group on Unilateral Spinal Anesthesia.Can J Anaesth. 2000; 47: 746-751Crossref PubMed Scopus (93) Google Scholar Eleven of the total 16 trials met all the factors of methodological quality and they have reported adequate methods for randomization, allocation, concealment, blinding, and completeness of follow-up. The remaining five trials9Bigat Z Boztug N Karsli B Cete N Ertok E Comparison of hyperbaric ropivacaine and hyperbaric bupivacaine in unilateral spinal anaesthesia.Clin Drug Investig. 2006; 26: 35-41Crossref PubMed Scopus (11) Google Scholar 22El-Halafawy YM Hyperbaric spinal levobupivacaine for outpatient knee arthroscopy: a comparison to bupivacaine and ropivacaine.Egypt J Anaesth. 2008; 20: 83-89Google Scholar 23Esmaoglu A Karaoglu S Mizrak A Boyaci A Bilateral vs. unilateral spinal anesthesia for outpatient knee arthroscopies.Knee Surg Sports Traumatol Arthrosc. 2004; 12: 155-158Crossref PubMed Scopus (33) Google Scholar 51Roussel JR Heindel L Effects of intrathecal fentanyl on duration of bupivacaine spinal blockade for outpatient knee arthroscopy.AANA J. 1999; 67: 337-343PubMed Google Scholar 58Valanne JV Korhonen AM Jokela RM Ravaska P Korttila KK Selective spinal anesthesia: a comparison of hyperbaric bupivacaine 4 mg versus 6 mg for outpatient knee arthroscopy.Anesth Analg. 2001; 93: 1377-1379Crossref PubMed Scopus (72) Google Scholar were associated with moderate risk of bias because they were not clear in the method of randomization, allocation, concealment, and blinding. There were five trials6Ben-David B Levin H Solomon E Admoni H Vaida S Spinal bupivacaine in ambulatory surgery: the effect of saline dilution.Anesth Analg. 1996; 83: 716-720Crossref PubMed Google Scholar 11Borghi B Stagni F Bugamelli S et al.Unilateral spinal block for outpatient knee arthroscopy: a dose-finding study.J Clin Anesth. 2003; 15: 351-356Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar 16Cappelleri G Aldegheri G Danelli G et al.Spinal anesthesia with hyperbaric levobupivacaine and ropivacaine for outpatient knee arthroscopy: a prospective, randomized, double-blind study.Anesth Analg. 2005; 101: 77-82Crossref PubMed Scopus (79) Google Scholar 37Kiran S Upma B Use of small-dose bupivacaine (3 mg vs 4 mg) for unilateral spinal anesthesia in the outpatient setting.Anesth Analg. 2004; 99: 302-303Crossref PubMed Scopus (9) Google Scholar 58Valanne JV Korhonen AM Jokela RM Ravaska P Korttila KK Selective spinal anesthesia: a comparison of hyperbaric bupivacaine 4 mg versus 6 mg for outpatient knee arthroscopy.Anesth Analg. 2001; 93: 1377-1379Crossref PubMed Scopus (72) Google Scholar comparing different doses of bupivacaine ranging from 3 to 15 mg. The trials include a total of 387 patients. Three trials had two comparison groups16Cappelleri G Aldegheri G Danelli G et al.Spinal anesthesia with hyperbaric levobupivacaine and ropivacaine for outpatient knee arthroscopy: a prospective, randomized, double-blind study.Anesth Analg. 2005; 101: 77-82Crossref PubMed Scopus (79) Google Scholar 37Kiran S Upma B Use of small-dose bupivacaine (3 mg vs 4 mg) for unilateral spinal anesthesia in the outpatient setting.Anesth Analg. 2004; 99: 302-303Crossref PubMed Scopus (9) Google Scholar 58Valanne JV Korhonen AM Jokela RM Ravaska P Korttila KK Selective spinal anesthesia: a comparison of hyperbaric bupivacaine 4 mg versus 6 mg for outpatient knee arthroscopy.Anesth Analg. 2001; 93: 1377-1379Crossref PubMed Scopus (72) Google Scholar and two trials had more than two groups6Ben-David B Levin H Solomon E Admoni H Vaida S Spinal bupivacaine in ambulatory surgery: the effect of saline dilution.Anesth Analg. 1996; 83: 716-720Crossref PubMed Google Scholar 11Borghi B Stagni F Bugamelli S et al.Unilateral spinal block for outpatient knee arthroscopy: a dose-finding study.J Clin Anesth. 2003; 15: 351-356Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar (Table 1). Time to onset of block, time to voiding, home discharge, and failure rates were compared in the five trials. The definition used to describe the onset of block was heterogeneous between the trials. The criteria for home discharge used in the trials were based on standard criteria of stable cardiovascular and respiratory system, ability to void and walk with crunches, but were not uniform between trials. Failure was considered when general anaesthesia had to be given because of inadequate block. In some trials, values were reported as mean (sd), and in others as median (range). The authors of these trials were contacted for more relevant data, but the response rate was poor. Therefore, statistical pooling of the data was not feasible.Table 1Studies on different doses of bupivacaine used for spinal anaesthesia in knee arthroscopy. Failure: required general anaesthesia for surgery because of inadequate spinal block. Values are mean (sd) or median (range). *Statistically significant values (P 240 min) and time to home discharge (>260 min) without any significant changes in time to the onset of sensory block
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