Comparison of L-bupivacaine 0.75% and lidocaine 2% with bupivacaine 0.75% and lidocaine 2% for peribulbar anaesthesia

F. Lai, B. Sutton and G. Nicholson

Department of Anaesthesia and Intensive Care Medicine, St George’s Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK

Corresponding author. E-mail: gnichols@sghms.ac.uk

Accepted for publication: November 23, 2002


    Abstract
 Top
 Abstract
 Introduction
 Methods and results
 Comment
 References
 
Background. L-Bupivacaine has a safer side-effect profile than bupivacaine. We compared the efficacy of a mixture of L-bupivacaine 0.75% and lidocaine 2% with bupivacaine 0.75% and lidocaine 2% for peribulbar anaesthesia in cataract surgery.

Methods. Ninety patients were allocated randomly to receive 8 ml of a mixture of equal parts of bupivacaine 0.75% and lidocaine 2% or an equal volume of L-bupivacaine and lidocaine 2%. Hyaluronidase 15 IU ml–1 was added to both solutions.

Results. There were significant differences between the groups in clinical end-points. The median time at which the block was adequate to start surgery was 4 min (interquartile range 4–8 min) in the bupivacaine group and 8 min (5–12 min) in the L-bupivacaine group (P=0.002). Median ocular and eyelid movement scores were similarly significantly decreased in the bupivacaine group compared with the L-bupivacaine group at all times (P<=0.03). There was no difference between groups in the incidence of minor complications.

Conclusions. A mixture of bupivacaine 0.75% and lidocaine 2% provides faster onset time than a mixture of L-bupivacaine 0.75% and lidocaine 2%.

Br J Anaesth 2003; 90: 512–14

Keywords: anaesthetic techniques, regional, peribulbar; anaesthetics local, levobupivacaine; anaesthetics local, lidocaine–bupivacaine; surgery, ophthalmological


    Introduction
 Top
 Abstract
 Introduction
 Methods and results
 Comment
 References
 
Regional anaesthesia with peribulbar block is the technique of choice for most patients undergoing cataract surgery. A mixture of bupivacaine and lidocaine is the most frequently used local anaesthetic; lidocaine providing rapid onset and bupivacaine a long duration of action.1 The proprietary form of bupivacaine is a racemic mixture of equal quantities of the two isomers levobupivacaine [L-bupivacaine or S(–)-bupivacaine] and dextrobupivacaine [D-bupivacaine or R(+)-bupivacaine]. Bupivacaine has potential, however, for cardiac and CNS toxicity and has been implicated in a number of reports of cardiac arrest and death.2 3

Both racemic bupivacaine and L-bupivacaine have local anaesthetic properties, but the latter drug is associated with a safer side-effect profile.4 5 A recent study has shown that L-bupivacaine 0.75%, when used as a single agent for peribulbar anaesthesia, compared favourably with racemic bupivacaine 0.75% in terms of safety and efficacy.6

However, if bupivacaine or L-bupivacaine is used as a single agent for peribulbar anaesthesia, then the onset of the block may be delayed by up to 13 min, with a corresponding delay in the time to start of surgery of up to 20 min.6 In this study, we compared the rapidity of onset and efficacy of peribulbar block obtained with equal volumes of L-bupivacaine 0.75% and lidocaine 2% with the traditional mixture of racemic bupivacaine 0.75% and lidocaine 2%. Hyaluronidase was added to both solutions. The major clinical end-points were ocular and eyelid movement scores at 8 min and the time to adequate block for surgery.


    Methods and results
 Top
 Abstract
 Introduction
 Methods and results
 Comment
 References
 
After local research ethics committee approval, 90 patients presenting for cataract surgery under local anaesthesia, who gave informed written consent, were included in the study. This study had a 95% chance of detecting a statistically significant (P<0.05) difference of two points for the sums of the ocular movement scores. Patients were excluded if they were unwilling to take part, if there were communication problems, or if there was a history of allergy to amide-type local anaesthetic agents. Patients were randomly allocated to one of two groups using a random number table. One group received a mixture of equal volumes of bupivacaine 0.75% and lidocaine 2%, whilst the other group received an equivalent volume of L-bupivacaine 0.75% and lidocaine 2%; hyaluronidase 15 IU ml–1 was added to both mixtures. The anaesthetic solution was warmed to body temperature using a Fibrinotherm (Ernst Biegler, Mauerbach, Austria).

Patients were not fasted and did not receive any premedication, perioperative sedation or supplementary oxygen. On arrival in the induction room, baseline eyelid and globe movements were assessed. Topical anaesthesia of the conjunctiva and cornea was achieved by administering oxybuprocaine 0.4%, 2–3 drops. Standard monitoring was started and i.v. access established. Peribulbar block was carried out, by one of two consultant anaesthetists, via a single inferolateral, transcutaneous or transconjunctival injection using a 25 gauge, 25 mm needle. After test aspiration, 8 ml of the local anaesthetic mixture was injected over 30–40 s. Manual compression and gentle massage of the eyeball were performed, after which a Visitec intraocular pressure reducer (Sarasota, FL, USA) inflated to 40 mm Hg was applied between scoring, to facilitate spread of the anaesthetic solution and to lower intraocular pressure. Patients were assessed for eyelid and ocular movements at 2 min intervals with a scoring system used by Brahma and colleagues.7 Scoring was carried out by a trained observer, who was blinded as to which local anaesthetic the patient had received.

Ocular movements were scored for each direction of gaze in a superior, inferior, medial and lateral direction with a maximum score for each direction of 3 points and a possible maximum total of 12 points. Ocular and eyelid movements were assessed at 2, 4, 6 and 8 and 10 min, until the block was considered adequate for surgery (eyelid movement score 0 and ocular movement score <=2). If the block was inadequate after 10 min, supplementary anaesthesia was provided with a further injection of up to 5 ml of the test solution, by the same technique. The time to adequate surgical anaesthesia and the need for supplementary anaesthesia were noted. It was assumed that, once motor block had been achieved, adequate sensory block was already present as this usually precedes motor block. Complications during or after injection were recorded and patients were specifically questioned about pain during insertion of the block, or during surgery.

The main outcome criteria were the differences in median ocular and eyelid movement scores at 8 min and the time needed to obtain adequate block to start surgery. The differences between groups were analysed with the Wilcoxon rank sum test. The number of patients who reached an ocular movement score of <=1, the need for further injections, delays to the start of surgery and the occurrence of complications were compared using the {chi}2-test or Fisher’s exact test, as appropriate. Statistical analysis was carried out using SPSS for Windows version 8 (SPSS, Chicago, IL, USA).

There were 45 patients in each group and all patient data were included in the statistical analysis. The mean (range) age in the bupivacaine group was 72 (39–88) yr and in the L-bupivacaine group 73 (45–91) yr. The male:female ratio was 22:23 in the bupivacaine group and 21:24 in the L-bupivacaine group.

Median eyelid movement scores were significantly lower in the bupivacaine group at all times. Ocular movement scores were significantly decreased in the bupivacaine group compared with the L-bupivacaine group at 2 min (P=0.002), 4 min (P=0.001), 6 min (P=0.001) and 8 min (P=0.012) (Table 1). The median (interquartile range) time at which the block was considered adequate to start surgery was 4 (4–8) min for the bupivacaine group and 8 (5–12) min for the L-bupivacaine group (P=0.002).


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Table 1 Median (interquartile range) ocular and eyelid movement scores and number of patients who required supplementary anaesthesia and developed complications. *Difference between groups (P<0.05). Data are median (interquartile range) unless indicated
 
Thirty-six patients in the bupivacaine group and 23 patients in the L-bupivacaine group had ocular movement scores <=1 at 8 min (P=0.09). Seven patients in the bupivacaine group and 16 patients in the L-bupivacaine group required supplementary analgesia (P=0.05). Minor complications occurred in one patient in the bupivacaine group (small periorbital haematoma). Only one patient in the L-bupivacaine group complained of slight pain during insertion of the initial block. No patient complained of pain during surgery. None of these differences were statistically significant.


    Comment
 Top
 Abstract
 Introduction
 Methods and results
 Comment
 References
 
L-Bupivacaine 0.75% in combination with lidocaine 2% was significantly less effective than bupivacaine 0.75% and lidocaine 2% for peribulbar anaesthesia in terms of speed of onset of anaesthesia. This surprising finding was in contrast to other studies, which found no difference between the two compounds in terms of time to satisfactory extradural block5 or peribulbar block.6 In the latter study, however, large volumes of L-bupivacaine 0.75% were used as a single agent and patients received up to three injections of local anaesthetic. In this study, we used a single injection technique and equal volumes of lidocaine 2% and either bupivacaine or L-bupivacaine, thereby reducing its concentration to 0.375%.

We were unable to assess the duration of motor block as patients’ eyes were bandaged and covered postoperatively and they were discharged home 1–2 h after surgery. If a shorter duration of motor block occurs with L-bupivacaine, this could be advantageous as prolonged paralysis from local anaesthesia leaves the eye vulnerable to drying and trauma.

Peribulbar anaesthesia requires relatively large volumes of local anaesthetic and concerns have been expressed about the potential for systemic toxicity. The incidence of peribulbar blocks requiring supplementary anaesthesia has been reported to be as high as 54%.8 However, L-bupivacaine is less toxic to the myocardium and central nervous system.9 10 While L-bupivacaine may have theoretical advantages in elderly patients with coexisting cardiac disease, the present study did not show any untoward effects with either drug. L-Bupivacaine did not demonstrate any advantages over racemic bupivacaine when used for peribulbar anaesthesia.


    Acknowledgement
 
We gratefully acknowledge the support of Abbott Pharmaceuticals, who provided supplies of L-bupivacaine and financial assistance.


    References
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 Abstract
 Introduction
 Methods and results
 Comment
 References
 
1 Wong DHW. Regional anaesthesia for intraocular surgery. Can J Anaesth 1993; 40: 635–57[Abstract]

2 Albright GA. Cardiac arrest following regional anaesthesia with etidocaine or bupivacaine. Anesthesiology 1979; 52: 285–7[ISI]

3 Heath M. Deaths after intravenous regional anaesthesia. Br Med J 1983; 285: 913–14[ISI]

4 McLeod GA, Burke D. Levobupivacaine. Anaesthesia 2001; 56: 331–41[CrossRef][ISI][Medline]

5 Cox CR, Faccenda KA, Gilhooly C, Bannister J, Scott NB. Extradural S(–)-bupivacaine: comparison with racemic RS-bupivacaine. Br J Anaesth 1998; 80: 289–93[Abstract/Free Full Text]

6 McLure HA, Rubin AP. Comparison of 0.75% levobupivacaine with 0.75% racemic bupivacaine for peribulbar anaesthesia. Anaesthesia 1998; 53: 1160–4[CrossRef][ISI][Medline]

7 Brahma AK, Pemberton CJ, Ayeko M, Morgan LH. Single medial injection peribulbar anaesthesia using prilocaine. Anaesthesia 1994; 49: 1003–5[ISI][Medline]

8 Loots JH, Koorts AS, Venter JA. Peribulbar anesthesia. A prospective statistical analysis of the efficacy and predictability of bupivacaine and a lidocaine/bupivacaine mixture. J Cataract Refract Surg 1993; 19: 72–6[ISI][Medline]

9 Kopacz DJ, Allen HW. Accidental intravenous levobupivacaine. Anesth Analg 1999; 89: 1027–9[Free Full Text]

10 Bardsley H, Gristwood R, Baker H, Watson N, Nimmo W. Comparison of the cardiovascular effects of levobupivacaine and rac-bupivacaine following intravenous administration to healthy volunteers. Br J Clin Pharmacol 1998; 46: 245–9[CrossRef][ISI][Medline]





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