Comparison of articaine and bupivacaine/lidocaine for single medial canthus peribulbar anaesthesia
K. G. Allman1,
J. G. McFadyen1,
J. Armstrong1,
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: June 12, 2001
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Abstract
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In a single-centre, randomized, double-blind study, we compared the efficacy of 2% articaine with that of a mixture of 0.5% bupivacaine and 2% lidocaine for peribulbar anaesthesia in cataract surgery, using a single medial canthus injection technique. Eighty-two patients were allocated randomly to receive 79 ml of a mixture of 0.5% bupivacaine and 2% lidocaine or an equal volume of 2% articaine with 1:200 000 epinephrine. Hyaluronidase 30 iu ml1 was added to both solutions. The degree of akinesia was scored 1, 5 and 10 min after the block, at the end of surgery and at discharge from the day case unit. Primary outcome measures were the difference in ocular movement scores 5 min after block and the need for supplementary inferolateral injections. There was greater akinesia in the articaine group at 5 min (P=0.01). Ten patients (24%) in the articaine group and 21 patients (51%) in the bupivacaine/lidocaine group required a supplementary injection (P=0.02). The mean (SD) volume of local anaesthetic required to achieve adequate block for surgery was 9.7 (2.1) ml in the articaine group and 11.0 (2.2) ml in the bupivacaine/lidocaine group (P=0.01). There was a faster offset of akinesia after surgery in the articaine group (P=0.01). There were no differences between groups in the incidence of reported pain or of minor complications. In our study, 2% articaine with 1:200 000 epinephrine was safe and efficacious for single medial canthus peribulbar anaesthesia.
Br J Anaesth 2001; 87: 5847
Keywords: surgery, ophthalmological; anaesthetic techniques, regional, peribulbar; anaesthetics local, articaine
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Introduction
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Articaine is a local anaesthetic synthesized in the 1960s and first investigated clinically in 1974.1 It is an amide, chemically similar to prilocaine, but it contains a thiophene rather than a benzene ring. It is currently the most widely used local anaesthetic for dental anaesthesia in Germany, Italy and the Netherlands, and has recently been introduced and licensed for dental use in the UK. Articaines widespread acceptance for dental anaesthesia is due to three main attributes. First, it has low toxicity (maximum recommended dose for dental infiltration is 7 mg kg1). Secondly, it appears to diffuse through tissues more readily than other local anaesthetic agents. Thirdly, it is metabolized by non-specific plasma esterases in blood and tissue, leading to rapid clearance. After i.v. injection, mean (SD) total body clearance of articaine is 532 (208) litre h1 and the volume of distribution in the central compartment is 2.4 litre kg1 [7.7 (5.1) litre kg1 at steady state].2 This profile makes articaine an ideal agent for peribulbar anaesthesia, an application that has not been examined previously.
Regional anaesthesia with peribulbar block is the technique of choice for most patients undergoing cataract surgery.3 A mixture of bupivacaine and lidocaine is the most frequently used local anaesthetic.4 Limited diffusion of local anaesthetic is the main drawback of peribulbar anaesthesia, leading to failure to achieve eyeball akinesia in up to 50% of patients.5 This lack of immobility can hinder surgical access. The other main problem with peribulbar anaesthesia is morbidity associated with the injections themselves. The complication rate for globe perforation or haemorrhage has been estimated to be between 0.1 and 1.7%.6 A single medial canthus injection technique to reduce the morbidity from repeated injections has been described.79 This technique has been shown to be safe, but supplementary injections are frequently required because of poor diffusion of local anaesthetic. We postulated that the use of articaine may reduce the need for supplementary injection because of improved diffusion.
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Methods
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With approval from the Local Research Ethics Committee and informed, written consent, 82 ASA IIII patients scheduled to undergo cataract surgery under local anaesthesia were enrolled in the study. A power calculation predicted 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 they were unwilling to take part, had communication problems, were allergic to amide-type local anaesthetic agents, or were known to have low plasma cholinesterase activity (scoline apnoea or taking ecothiopate eye drops), as this may affect the metabolism of articaine by plasma esterases.
Patients were allocated randomly to one of two groups using sealed, numbered envelopes and computer randomization with Arcus Quickstat software (CamCode, Cambridge, UK). Group 1 received 2% articaine with 1:200 000 epinephrine and group 2 received a mixture of equal volumes of 0.5% bupivacaine and 2% lidocaine. Hyaluronidase 30 iu ml1 was added to both solutions.
Patients were not fasted and did not receive any premedication.
On arrival in the anaesthetic room, pulse oximetry, non-invasive arterial pressure and electrocardiographic monitoring was started and i.v. access secured. Patients requesting sedation were given alfentanil 250 µg and midazolam 12 mg i.v. Oxybuprocaine 0.4% drops were instilled onto the conjunctival sac. One of two consultant anaesthetists, blinded to the local anaesthetic used, performed peribulbar anaesthesia and scored the progression of akinesia. Peribulbar anaesthesia was performed using a single medial canthus injection as described by Ripart and colleagues.8 9 After test aspiration, local anaesthetic was injected using a 22 mm, 25 G peribulbar short-bevel Atkinson needle (Visitec, Bidford-on-Avon, UK). The maximum injection volume was 9 ml and injection was stopped if signs of proptosis developed. Gentle digital massage of the eyeball was undertaken for 1 min, after which a Honans balloon, inflated to 30 mm Hg, was applied to facilitate diffusion of local anaesthetic and decrease intra-ocular pressure.
Patients were assessed for ocular and eyelid movements 1, 5 and 10 min after injection, on completion of surgery and before discharge from the day surgery unit, using the scoring system of Brahma and colleagues.7 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 score of 12 points. Eyelid movement was scored, with a maximum score of 2 (Table 1).
If after 5 min there was full movement in any direction or a total ocular movement score of 6 or greater, supplementary anaesthesia was provided with an inferolateral injection of 35 ml of the test solution. A further inferolateral injection was performed if the block was still inadequate after 10 min. The need for supplementary local anaesthesia and the total volume of local anaesthetic required was recorded. The surgeon, also blinded to the local anaesthetic used, assessed the degree of proptosis and chemosis before surgery and the degree of akinesia and analgesia during surgery. Visual acuity (light perception, hand movement, counting fingers) was assessed at the start of surgery and before discharge. Pain and complications during injection and during surgery were noted. Patients were questioned immediately before discharge about pain during injection and surgery.
Primary outcome measures were the difference in median ocular and eyelid movement scores at 5 min and the need for supplementary local anaesthesia. Secondary outcome measures were ocular and eyelid movement scores at 1 and 10 min, the end of surgery and on discharge, total volume of local anaesthetic used, and complications.
Statistical analysis of data, using Arcus Quickstat software, involved a two-tailed Students t-test for age, axial length and total volume of local anaesthetic and the
2 test or Fishers exact test for sex, supplementary injections, complications and visual acuity. A two-tailed Wilcoxon rank sum test was used for comparing ocular and eyelid movement scores. P<0.05 was considered statistically significant.
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Results
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There were 41 patients in each group and all patient data were included in the statistical analysis. No patients met the exclusion criteria for the study. There were no significant differences in patient characteristics between the two groups (Table 2).
Median ocular movement scores were significantly reduced in group 1 at 5 min (P=0.01) (Fig. 1). Ten patients (24%) in group 1 required supplementary local anaesthesia compared with 21 patients (51%) in group 2 (P=0.02). One patient in group 2 required a third injection. There was no significant difference in median ocular movement scores at 1 min, 10 min and at the end of surgery. Median eyelid opening scores were lower in group 1 at 1 and 5 min (P=0.02) (Table 3). The mean (SD) time from initial injection to the end of surgery was 44 (14) min in group 1 and 42 (13) min in group 2 (P=0.56). The mean (SD) time from insertion of the block to discharge assessment was 104 (25) min in group 1 and 114 (30) min in group 2 (P=0.2). The ocular movement score was significantly higher in group 1 before discharge from the day case unit (P<0.01). The mean (SD) total volume of local anaesthetic was 9.7 (2.1) ml in group 1 and 11.0 (2.2) ml in group 2 (P=0.01). There was no significant difference in visual acuity between groups at the start of surgery or on discharge.

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Fig 1 Median (interquartile range and range) ocular movement scores. Art = articaine; B/L = bupivacaine/lidocaine. Significant differences at 5 min (P=0.01) and discharge (P<0.01).
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One patient in group 2 complained of pain during surgery, which was treated with oxybuprocaine drops to the conjunctiva. On specific questioning before discharge, six patients in group 1 and eight patients in group 2 reported minimal pain during surgery, which they had not mentioned at the time of surgery.
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Discussion
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The technique of single medial canthus injection has several possible advantages over dual injection techniques. These include decreased pain and risk of globe perforation with single needle insertion and injection in an avascular area, reducing the risk of haemorrhage or intravascular injection. These advantages are reduced if a supplementary injection is required. In our study, the number of patients in the articaine group requiring a second injection was 24% compared with 51% in the bupivacaine/lidocaine group (P=0.02). This may reflect better diffusion of articaine from the medial orbital compartment to the eyelids and muscle cone. Ripart and colleagues8 reported a supplementary injection rate of 9.27% at 15 min using 0.5% bupivacaine alone or with 1% etidocaine or 2% lidocaine, plus hyaluronidase 25 iu ml1. They reported a learning curve: in the first 30 patients, 26.6% required a supplementary injection. Brahma and colleagues7 found that a single medial canthus injection using prilocaine 3% with felypressin provided a safe and effective peribulbar block. Their re-block rate, using timing and criteria for supplementary injection similar to those in our study, was 9.7%. However, they used hyaluronidase 125 iu ml1, whereas we used 30 iu ml1. We discontinued the use of prilocaine after the manufacturer issued a report in January 2000 of three cases of optic atrophy and one of cilioretinal occlusion after the use of 3% prilocaine with felypressin for peribulbar anaesthesia.
The ideal agent for peribulbar anaesthesia must be safe and give a rapid onset of anaesthesia, a dense motor block and an adequate duration of action for surgery, but must not prolong akinesia.10 11 We have demonstrated that articaine satisfies many of these criteria. Articaine has a wider therapeutic index than lidocaine whilst having similar potency.2 In our study, articaine had a more rapid onset of action, resulting in better akinesia at 5 min than a bupivacaine/lidocaine mixture. There was less requirement for a supplementary injection. The likelihood of complications was therefore reduced. Our surgeon did not assess akinesia during surgery as poor in any of the patients in the articaine group (Table 4). The duration of block was adequate for surgery in all cases. Articaine had a faster offset than bupivacaine/lidocaine, with quicker return of protective reflexes and less likelihood of inadvertent damage to an anaesthetized eye when the patient was discharged after surgery.
In summary, our study suggests that 2% articaine with epinephrine 1:200 000 is as safe as and more efficacious than a mixture of 0.5% bupivacaine and 2% lidocaine for single medial canthus peribulbar anaesthesia (Table 5). There is a lower risk of globe perforation as a result of a lower requirement for supplementary injection. Fewer supplementary injections before surgery and quicker return of protective reflexes after surgery can result in a faster throughput of patients having cataract surgery. Articaine is less expensive than bupivacaine at current UK prices.
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Acknowledgements
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We gratefully acknowledge the support of Deproco UK, who provided supplies of articaine free of charge. We thank Bob Rees (senior ODA) and all the staff of the West of England Eye Unit for their help during the study.
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References
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1 Winther JE, Patirupanusara B. Evaluation of carticainea new local analgesic. Int J Oral Surg 1974; 3: 4227[Medline]
2 Oertel R, Rahn R, Kirch W. Clinical pharmacokinetics of articaine. Clin Pharmacokinet 1997; 33: 41725[ISI][Medline]
3 Barker JP, Vafidis GC, Hall GM. Postoperative morbidity following cataract surgery. A comparison of local and general anaesthesia. Anaesthesia 1996; 51: 4357[ISI][Medline]
4 Wong DWH. Regional anaesthesia for intraocular surgery. Can J Anaesth 1993; 40: 63557[Abstract]
5 Hamilton RC. Techniques of orbital regional anaesthesia. Br J Anaesth 1995; 75: 8892[Free Full Text]
6 Rubin AP. Complications of local anaesthesia for ophthalmic surgery. Br J Anaesth 1995; 75: 936[Free Full Text]
7 Brahma AK, Pemberton CJ, Ayeko M, Morgan LH. Single medial injection peribulbar anaesthesia using prilocaine. Anaesthesia 1994; 49: 10035[ISI][Medline]
8 Ripart J, Lefrant JY, Lalourcey L, et al. Medial canthus (caruncle) single injection periocular anesthesia. Anesth Analg 1996; 83: 12348[Abstract]
9 Ripart J, Metge L, Prat PD, Lopez FM, Eledjam JJ. Medial canthus single-injection episcleral (sub-Tenon anesthesia): computed tomography imaging. Anesth Analg 1998; 87: 425[Abstract]
10 Dopfmer UR, Maloney DG, Gaynor PA, Ratcliffe RM, Dopfmer S. Prilocaine 3% is superior to a mixture of bupivacaine and lignocaine for peribulbar anaesthesia. Br J Anaesth 1996; 76: 7780[Abstract/Free Full Text]
11 McLure HA, Rubin AP, Westcott M, Henderson H. A comparison of 1% ropivacaine with a mixture of 0.75% bupivacaine and 2% lignocaine for peribulbar anaesthesia. Anaesthesia 1999; 54: 117882[ISI][Medline]