Comparison of articaine and bupivacaine/lidocaine for peribulbar anaesthesia by inferotemporal injection

K. G. Allman*,1, L. L. Barker1, G. C. Werrett1, P. Gouws2, G. D. Sturrock2 and I. H. Wilson1

1Department of Anaesthesia and 2West of England Eye Unit, Royal Devon and Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK*Corresponding author

Accepted for publication: January 10, 2002


    Abstract
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
Background. Articaine is a novel amide local anaesthetic with a shorter duration of action than prilocaine.

Methods. In a randomized, double-blind study we compared the efficacy of 2% articaine with epinephrine 1:200 000 with a mixture of 0.5% bupivacaine and 2% lidocaine with epinephrine 1:200 000 for peribulbar anaesthesia in cataract surgery using a single inferotemporal injection. Eighty-two patients were randomly allocated to one of two groups to receive peribulbar anaesthesia with 6–7 ml of articaine or a bupivacaine/lidocaine mixture. Both solutions contained hyaluronidase 30 iu ml–1. Ocular movement was scored at 2 min intervals up to 10 min, at the end of surgery and at time of discharge from hospital. Time to readiness for surgery and any complications (proptosis, chemosis, pain) were recorded.

Results. The articaine group demonstrated a rapid onset of peribulbar block with mean time (SD) to readiness for surgery of 4.2 (4.5) min compared with 7.2 (5.7) min in the bupivacaine/lidocaine group (P=0.0095). The block obtained in the articaine group was dense with eye movement scores at 2, 4, 6, 8 and 10 min all significantly reduced (P<0.01 at each interval). There was also a faster offset of the block in the articaine group (P=0.0009). There was no difference in incidence of minor complications between the groups.

Conclusions. Two per cent articaine is safe and effective for peribulbar anaesthesia by inferotemporal injection and is a suitable alternative to the traditional mixture of 0.5% bupivacaine and 2% lidocaine.

Br J Anaesth 2002; 88: 676–8

Keywords: surgery, ophthalmological; anaesthetic techniques, regional, peribulbar; anaesthetics local, articaine


    Introduction
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
Articaine is a novel amide local anaesthetic which diffuses rapidly through tissues and has a rapid onset of action with a wide therapeutic index (maximum recommended dose for dental anaesthesia 7 mg kg–1). Articaine is chemically similar to prilocaine, but contains an extra ester group that is hydrolysed by plasma esterases resulting in a short duration of action and low risk of systemic toxicity.1

We have recently shown articaine to be superior to a standard mixture of 0.5% bupivacaine and 2% lidocaine for peribulbar anaesthesia using a single medial canthus technique.2 Although peribulbar block has been described by single medial canthus injection,35 the inferotemporal approach is used more commonly in the UK and is widely described both as a dual injection technique6 7 and as a single injection technique.8 9 In this study, we compared the effect of 2% articaine with 1:200 000 epinephrine and a traditional mixture of 0.5% bupivacaine and 2% lidocaine with 1:200 000 epinephrine using the more conventional inferotemporal approach for peribulbar anaesthesia.


    Methods
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
Local Research Ethics Committee approval was granted and a clinical trials exemption certificate obtained. Eighty-two patients attending the West of England Eye Unit for cataract surgery gave written, informed consent. The sample size was determined on the basis of a power calculation. This study had a 90% 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 unwilling to participate in the study, if there was a history of allergy to amide-type local anaesthetics, or if they were known to have reduced plasma cholinesterase concentration (possibly reduced metabolism of articaine).

Patients were randomly allocated to one of two groups using sealed, numbered envelopes and computer randomization (Arcus Quickstat software, CamCode, Cambridge, UK). Group 1 received peribulbar anaesthesia using 2% articaine with epinephrine 1:200 000 and Group 2 received a mixture of equal volumes of 0.5% bupivacaine and 2% lidocaine with epinephrine 1:200 000. Hyaluronidase 30 iu ml–1 was added to both solutions.

Patients were not fasted and did not receive any premedication. On arrival in the anaesthetic room, monitoring of arterial oxygen saturation, ECG, and non-invasive blood pressure was commenced. Intravenous access was secured and patients were given sedation upon request (alfentanil 125–250 µg and midazolam 0.5–2 mg i.v.). Analgesia of the conjunctiva and cornea was provided by the topical administration of 0.4% oxybuprocaine drops. Peribulbar block was then performed by single inferotemporal injection by one of two consultant anaesthetists blinded to the local anaesthetic mixture. A 25 gauge 25 mm sharp disposable needle (BD Medical Systems, Drogheda, Ireland) was inserted inferolaterally and transconjunctivally past the equator of the globe then redirected upwards and inwards (10–20°). After negative aspiration, 6–7 ml of local anaesthetic solution was injected. Digital massage was undertaken for 2 min. Eyeball movement was then assessed using the scoring system described by Brahma and colleagues3 at 2, 4, 6, 8 and 10 min. Ocular movements were scored for each direction of gaze in the superior, inferior, medial and lateral directions with a maximum score for each direction of 3 points and a possible total maximum of 12 points (Table 1).


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Table 1 Scoring system for degree of akinesia
 
The block was considered inadequate for surgery if eyeball movement score was 2 or more in any direction at 10 min. If this occurred, a second injection was performed at the medial canthus and a further 3–4 ml of the local anaesthetic mixture administered. The need for supplementary anaesthesia, the total volume required and any complications experienced were recorded. The surgeon (also blinded to the local anaesthetic solution used) assessed visual acuity and the degree of proptosis and chemosis prior to surgery. Time to readiness for surgery was noted when the ocular movement score was 4 or less. Patients were questioned specifically about pain experienced during insertion of the block and postoperatively about pain during surgery. Prior to discharge, visual acuity was assessed and eyeball movement scored.

Statistical analysis was performed using Arcus Quickstat software. The Wilcoxon rank sum test was used to compare ocular movement scores. Student’s t-test was used for age, axial length, and volume of local anaesthetic and the {chi}2 test for gender, supplementary injections, complications and visual acuity. P<0.05 was considered to be statistically significant for the Student’s t-test and {chi}2 test, but P<0.01 was used for eye movement scores to avoid error from repeated statistical analysis.


    Results
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
There were 40 patients in the articaine group and 42 patients in the bupivacaine/lidocaine group. All patient data were included in the statistical analysis. No patients were excluded. Patient characteristics in the two groups were similar and no significant differences were detected (Table 2).


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Table 2 Patient and surgical characteristics. Values are mean (SD) where appropriate
 
Median ocular movement scores were significantly reduced in the articaine group at 2, 4, 6, 8 and 10 min and at the end of surgery, and increased prior to discharge (Table 3). The mean (SD) time from block insertion to readiness for surgery was 4.4 (4.5) min in the articaine group and 7.2 (5.7) min in the bupivacaine/lidocaine group (P=0.0095). There was no difference in surgical duration between the two groups. Six (15%) patients required a supplemental medial canthus injection in the articaine group compared with 13 (31%) in the bupivacaine/lidocaine group (P=0.147). Mean total volume of local anaesthetic used was 7.2 (1.4) ml in the articaine group vs 8.0 (2.0) ml in the bupivacaine/lidocaine group (P=0.0265).


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Table 3 Ocular movement scores. Values are median (interquartile range). *P<0.01
 
There was no difference in visual acuity at the beginning and end of the procedure in the two groups. No significant differences in complications during the procedure (pain, proptosis, chemosis) were noted although four patients in the bupivacaine/lidocaine group complained of some discomfort during surgery and two required supplemental analgesia (Table 4). In these two cases, oxybuprocaine drops were administered with good effect. Despite no evidence of intraoperative distress, when directly questioned postoperatively, five additional patients complained of experiencing mild discomfort during surgery which was not disclosed at the time (two patients in the articaine group and three patients in the bupivacaine/lidocaine group). No serious complications were noted.


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Table 4 Complications during injection and surgery
 

    Discussion
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
We have demonstrated that peribulbar anaesthesia using a single inferotemporal injection with 2% articaine and epinephrine 1:200 000 is effective and provides a suitable alternative to a mixture of 0.5% bupivacaine/2% lidocaine with epinephrine 1:200 000. The articaine group had a more rapid onset of akinesia with time to readiness for surgery significantly reduced compared with the bupivacaine/lidocaine group. In addition, the articaine group had greater eye movement scores by the time of discharge. This is advantageous as prolonged ocular anaesthesia makes the eye vulnerable to trauma and drying. The motor block produced by articaine was dense with fewer top-ups required. Total volume used was less in the articaine group which may have facilitated surgery by avoiding hypertonia. Articaine has a wide therapeutic range with low systemic toxicity and no unexpected problems were encountered.

Whilst plain local anaesthetic solutions can be used for peribulbar anaesthesia, epinephrine-containing solutions are also commonly used to reduce systemic absorption and prolong local anaesthetic activity.10 11 Epinephrine may, however, cause problems of vasospasm in end arterioles, arrythmias following inadvertent intravascular injection and allergy to the metabisulphite preservative.12 We chose to use articaine with epinephrine as previous data suggested that the duration of action of plain articaine may not be sufficient for cataract surgery.1 We are now investigating the duration of action of plain articaine after sub-Tenon administration.


    Acknowledgements
 
We gratefully acknowledge the support of Deproco UK who provided supplies of articaine free of charge. We also thank all the staff of the West of England Eye Unit for their help during the study.


    References
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 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
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12 Schwartz HJ, Gilbert IA, Lenner KA, Sher TH, McFadden ER. Metabisulfite sensitivity and local dental anaesthesia. Ann Allergy 1989; 62: 83–6[ISI][Medline]