The effects of adrenaline, hyaluronidase and age on peribulbar anaesthesia

Use of hyaluronidase as an adjunct to local anaesthetic eye blocks to reduce intraoperative pain in adults

BACKGROUND

Hyaluronidase has been used over many decades as an adjunct to local anaesthetic solution to improve the speed of onset of eye blocks and to provide better akinesia and analgesia. With the evolution of modern eye surgery techniques, fast onset and akinesia are not essential requirements anymore. The assumption that the addition of hyaluronidase to local anaesthetic injections confers better analgesia for the patient needs to be examined. There has been no recent systematic review to provide evidence that hyaluronidase actually improves analgesia.

OBJECTIVES

To ascertain if adding hyaluronidase to local anaesthetic solutions for use in ophthalmic anaesthesia in adults results in a reduction of perceived pain during the operation and to assess harms, participant and surgical satisfaction, and economic impact.

SEARCH METHODS

We carried out systematic searches in Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and four other databases in June 2017. We searched the trial registers at www.ISRCTN.com, ClinicalTrials.gov and www.clinicaltrialsregister.eu for relevant trials. We imposed no language restrictions.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that evaluated the effect of hyaluronidase on pain experienced by adults during intraocular surgery using a rating scale.

DATA COLLECTION AND ANALYSIS

Two review authors (HR and KA) independently extracted data and assessed methodological quality using standard procedures as expected by Cochrane.

MAIN RESULTS

We included seven trials involving 500 participants that studied the effect of hyaluronidase on intraoperative pain. Four of the seven trials with 289 participants reported the primary outcome in a dichotomous manner, and we proceeded to meta-analyse the findings which showed a moderate heterogeneity that could not be explained (I² = 41% ). The pooled risk ratio (RR) for these four trials was 0.83 with the 95% confidence interval ranging from 0.48 to 1.42. The reduction in intraoperative pain scores in the hyaluronidase group were not statistically significant. Among the three trials that reported the primary outcome in a continuous manner, the presence of missing data made it difficult to conduct a meta-analysis. To further explore the data, we imputed standard deviations for the other studies from another included RCT (Sedghipour 2012). However, this resulted in substantial heterogeneity between study estimates (I² = 76% ). The lack of reported relevant data in two of the three remaining trials made it difficult to assess the direction of effect in a clinical setting.Overall, there was no statistical difference regarding the intraoperative reduction of pain scores between the hyaluronidase and control group. All seven included trials had a low risk of bias.According to GRADE, we found the quality of evidence was low and downgraded the trials for serious risk of inconsistency and imprecision. Therefore, the results should be analysed with caution.Participant satisfaction scores were significantly higher in the hyaluronidase group in two high quality trials with 122 participants. Surgical satisfaction was also superior in two of three high quality trials involving 141 participants. According to GRADE, the quality of evidence was moderate for participant and surgical satisfaction as the trials were downgraded for imprecision due to the small sample sizes. The risk of bias in these trials was low.There was no reported harm due to the addition of hyaluronidase in any of the studies. No study reported on the cost of hyaluronidase in the context of eye surgery.

AUTHORS' CONCLUSIONS

The effects of adding hyaluronidase to local anaesthetic fluid on pain outcomes in people undergoing eye surgery are uncertain due to the low quality of evidence available. A well designed RCT is required to address inconsistency and imprecision among the studies and to determine the benefit of hyaluronidase to improve analgesia during eye surgery. Participant and surgical satisfaction is higher with hyaluronidase compared to the control groups, as demonstrated in moderate quality studies. There was no harm attributed to the use of hyaluronidase in any of the studies. Considering that harm was only rarely defined as an outcome measure, and the overall small number of participants, conclusions cannot be drawn about the incidence of harmful effects of hyaluronidase. None of the studies undertook cost calculations with regards to use of hyaluronidase in local anaesthetic eye blocks.

The INFUSE-Morphine IIB study: use of recombinant human hyaluronidase (rHuPH20) to enhance the absorption of subcutaneous morphine in healthy volunteers

Morphine is usually given intravenously (IV) for the treatment of moderate-to-severe pain, but subcutaneous (SC) administration is a viable alternative for parenteral delivery. The pharmacokinetics of SC morphine may be enhanced by coadministration with a hyaluronidase product. In this Phase IV, double-blind, randomized, crossover study, 18 healthy adults received a single dose of 2mg morphine SC with 150U of recombinant human hyaluronidase (rHuPH20), SC with 0.9% normal saline, or IV on three consecutive days. The primary endpoint was time to maximum plasma morphine concentration (T(max)) for SC injection with rHuPH20 vs. SC injection without rHuPH20. Safety and tolerability were assessed each study day, the day after the last injection, and 28 days after the last injection. After SC dosing, morphine mean T(max) was significantly shorter with rHuPH20 than without it. Mean maximum plasma morphine concentration (C(max)) after SC dosing was 29% greater with rHuPH20 than without rHuPH20 (P=0.023), although the extent of exposure of morphine was similar. T(max) was shortest and C(max) was highest with IV administration. For the major active metabolite of morphine, morphine-6-glucuronide, mean T(max) after SC morphine was significantly shorter with rHuPH20 than without rHuPH20 (a difference of approximately 17.5 minutes; P=0.0169). Coadministration of morphine with rHuPH20 appeared safe and well tolerated. Compared with SC morphine alone, rHuPH20 shortens morphine T(max) and raises C(max) in healthy adults, without changing the extent of exposure.

The INFUSE-Morphine study: use of recombinant human hyaluronidase (rHuPH20) to enhance the absorption of subcutaneously administered morphine in patients with advanced illness

Morphine is often administered by the subcutaneous (SC) route when venous access is difficult to achieve. Hyaluronidase temporarily increases the permeability of SC connective tissues by degrading hyaluronan and has been shown to increase the dispersion and absorption of coadministered molecules. Therefore, hyaluronidase could enhance the pharmacokinetics of subcutaneous morphine. This Phase IIIB, double-blind, randomized, placebo-controlled crossover study compared the pharmacokinetics, safety, and tolerability of morphine administered SC with and without 150U of recombinant human hyaluronidase (rHuPH20) with those of intravenous (IV) morphine administration in 13 patients in a hospice or palliative care setting. Each patient received morphine 5mg parenterally daily for three days by a different method each day: IV, SC plus rHuPH20, and SC plus placebo (normal saline). The primary endpoint was the time to maximum plasma concentration (T(max)) for morphine. Concomitant SC administration of rHuPH20 enhanced the absorption rate of morphine compared with SC morphine with placebo, significantly reducing the mean T(max) from 13.8 to 9.2 minutes, a 33% decrease (P=0.026). The respective values for geometric mean maximum plasma concentration were 94.9 and 107.5nmol/L, a 13% increase (P=0.024), and the area under the plasma concentration vs. time curve values were 7.7 and 7.2micromol x min/L (P=0.23). Morphine plus rHuPH20 appeared to be safe and well tolerated. In patients requiring opioid analgesia, SC morphine plus rHuPH20 provides pharmacokinetic characteristics that are superior to those of SC morphine alone. These positive results warrant further studies on analgesic efficacy of morphine delivered with rHuPH20.

[Hyaluronidase: Here we go again]

OBJECTIVE

To summarize the benefits and lateral effects of hyaluronidase (H) use in ophthalmologic anaesthesia and to address its unavailability in current practice in France.

DATA SOURCES

The Medline data bank and the Cochrane database were consulted. The keywords employed separately or in combination were: H, regional anaesthesia, ophthalmologic surgery, local aneasthetics myotoxicity, diplopia.

STUDY SELECTION

Original articles since 1949 were selected. We also selected isolated clinical cases according to their relevance compared with the existing literature.

DATA SYNTHESIS

H is a "spreading factor" of animal origin used as an adjuvant in ophthalmic anaesthesia for more than half a century. It allows a moderate better block quality with a slightly quicker onset. It also limits the acute intraocular pressure increase secondary to periocular injection and seems to have a protective effect against local anaesthetics myotoxicity resulting in postoperative strabismus. However, during these last 50 years, numerous studies often ended in divergent results.

CONCLUSION

H seems to be a useful adjuvant in ophthalmologic anaesthesia in spite of his current unavailability in France. Recombinant H could be the solution in the near future.

Assessment and implication of the allergic sensitivity to a single dose of recombinant human hyaluronidase injection: a double-blind, placebo-controlled clinical trial

Animal-extracted injectable hyaluronidases have been used safely for more than 50 years to increase the dispersion and absorption of coadministered drugs and fluids; however, concern still exists about the allergic and immunological risks of these products. Hylenex recombinant, a novel formulation of recombinant human hyaluronidase, has been developed as an alternative to these animal-derived hyaluronidases. Because recombinant human hyaluronidase is a human (nonforeign) protein manufactured into a purer preparation than the animal extracts, it is expected to convey reduced allergic and immunologic risks. The recombinant human hyaluronidase product was well tolerated in this double-blind, placebo-controlled, single-dose study. No allergic reactions were observed among the 100 volunteer subjects who were injected intradermally. These findings supported the US Food and Drug Administration approval of the recombinant human hyaluronidase product.

Complications of ophthalmic regional blocks: their treatment and prevention

Complications following ophthalmic regional anaesthesia are rare but are reported during both needle (intraconal and extraconal blocks) and blunt cannula (sub-Tenon's block) techniques. At present there is no perfect technique of ophthalmic regional anaesthesia. This article reports on the complications, treatment and prevention of commonly used ophthalmic regional blocks. Thorough knowledge of the measures required to deal with complications when they occur are of paramount importance for safe clinical practice.

Advances in ophthalmic regional anaesthesia

Although retrobulbar and peribulbar regional anaesthetic techniques are used (by both anaesthesiologists and ophthalmologists) in various types of eye surgery, topical anaesthesia of the conjunctiva and cornea, followed--as needed--by sub-Tenon's block, is now common in routine cataract surgery. Intracameral administration of local anaesthetic by the ophthalmologist is also performed. Sedation during ophthalmic surgery is distinctly lighter than for other surgery because it is essential that the patient remains alert and can cooperate with the surgeon. Continuous insufflation of oxygen-enriched air is needed to ascertain that CO2 has been flushed away. With a catheter placed into the nostril, the patient (whose head is draped and 'hidden') can have the end-tidal CO2 monitored. Finger index (FI), a palpation method that assesses the ease of performing retrobulbar block, is introduced. Because of the risk of life-threatening complications in ophthalmic regional anaesthesia, the services of an anaesthesiologist must be available and training of anaesthesia residents in ophthalmic regional anaesthesia is highly recommended.

Comparison of articaine and bupivacaine/lidocaine for sub-Tenon's anaesthesia in cataract extraction

BACKGROUND

Articaine is 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. We have previously shown articaine to be superior to a standard mixture of bupivacaine 0.5%/lidocaine 2% for peribulbar anaesthesia. Sub-Tenon's anaesthesia arguably provides a safer method of anaesthetic delivery for cataract surgery. A blunt cannula is used in this technique, thus greatly reducing the risk of globe perforation, intrathecal injection and sight-threatening periocular haemorrhage.

METHODS

We compared articaine and bupivacaine/lidocaine for sub-Tenon's anaesthesia in cataract surgery.

RESULTS

Sub-Tenon's anaesthesia using articaine 2% resulted in a more rapid onset of motor block compared with a bupivacaine/lidocaine (P=0.0076). Ocular movement scores were significantly lower from 2 min after injection until the end of surgery (P=0.031 ANOVA).

CONCLUSION

Articaine 2% is safe and effective for sub-Tenon's anaesthesia and is a suitable alternative to the traditional bupivacaine 0.5%/lidocaine 2% mixture.

The efficacy and safety of 0.75% levobupivacaine vs 0.75% bupivacaine for peribulbar anaesthesia

BACKGROUND

Levobupivacaine, the S(-)-enantiomer of racemic bupivacaine, is associated with a similar efficacy but a reduced potential for cardiovascular and central nervous system toxicity than racemic bupivacaine. Thus, this prospective, randomised, double-masked study was undertaken to assess the efficacy and safety of 0.75% levobupivacaine vs 0.75% bupivacaine, each with hyaluronidase, for peribulbar anaesthesia.

METHODS

A total of 60 patients undergoing elective anterior segment surgery were randomly allocated to receive either agent by a single, inferotemporal peribulbar injection technique, supplemented with a medial canthus injection if necessary. Ocular akinesia and orbicularis oculi function were assessed by scoring systems at 2 min intervals until satisfactory akinesia was achieved, and movements were reassessed on the day after surgery to confirm regression of the block.

RESULTS

The time taken to reach a state of satisfactory anaesthesia and akinesia was deemed to be the primary measure of efficacy. Both agents achieved this in a similar median time of 2 min after receiving 5 ml of the injectate, and the treatment difference was not statistically significant (P=0.24). Blood samples from the first 20 patients were taken at intervals up to 4 h. These were analysed for plasma levels and confirmed similar plasma concentration vs time profiles for the two agents. Seven patients in each group (23%) complained of pain on injection but the technique was generally well tolerated. Two patients in the levobupivacaine group experienced serious adverse events, but neither was considered related to the study medication. The most common minor post-operative adverse event was prolongation of the local anaesthetic block, which was reported by nine patients (four in the levobupivacaine group and five in the bupivacaine group).

CONCLUSIONS

Levobupivacaine and bupivacaine are equally successful in achieving clinically satisfactory peribulbar anaesthesia with few adverse effects.

Effect of hyaluronidase on ocular motility in sub-Tenon's anesthesia: randomized controlled trial

PURPOSE

To assess the effect of hyaluronidase additive on the onset and degree of ocular akinesia in sub-Tenon's anesthesia for cataract surgery.

SETTING

Routine cataract operating list.

METHOD

This double-blind randomized controlled study comprised 100 patients who had phacoemulsification cataract surgery. Patients were randomized to 1 of 2 groups. For sub-Tenon's anesthesia, Group A received 5 mL lignocaine 2% with sodium hyaluronidase 150 IU/mL and Group B, 5 mL plain lignocaine 2%. Akinesia was assessed by scoring movement in the 6 positions of gaze. Scores ranged from 0 (complete akinesia) to 3 (no akinesia). Movements were measured at 30 seconds and 1, 3, 5, and 10 minutes. Changes in motility scores were compared by the Mann-Whitney U test.

RESULTS

There was no significant difference in akinesia between the 2 groups 30 seconds after the injection (P =.224); however, at 1 and 3 minutes, Group A achieved significantly better akinesia than Group B (P =.003 and P =.023, respectively). The median score after 3 minutes was 3.5 (interquartile range 0 to 7.5) in Group A and 7.0 (interquartile range 2.5 to 10.0) in Group B. There was no significant difference between the groups at 5 and 10 minutes (P =.225 and P =.831, respectively).

CONCLUSIONS

The addition of hyaluronidase in sub-Tenon's anesthesia significantly improved the rapidity of the onset of akinesia. This benefit disappeared over time; after 5 minutes the akinesia observed in the group receiving hyaluronidase was similar to that in the group receiving lignocaine alone. Thus, there appears to be no benefit to adding hyaluronidase to the anesthetic solution in terms of final ocular akinesia.

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

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.

Comparison of lignocaine 2% with adrenaline, bupivacaine 0.5% with or without hyaluronidase and a mixture of bupivacaine, lignocaine and hyaluronidase for peribulbar block analgesia

PURPOSE

Each of the freely available local analgesic agents may be used, alone or in combination, with or without hyaluronidase, epinephrine and sodium bicarbonate for peribulbar block analgesia (PBA). A prospective audit of four solutions was undertaken to rationalize choice of local analgesic agent for PBA.

METHODS

A randomized, prospective study on 200 middle-aged to elderly patients undergoing cataract extraction was undertaken to compare the efficacy of: (1) bupivacaine 0.5% (bup 0.5% plain); (2) bupivacaine 0.5% plus hyaluronidase 100 i.u. ml-1 (bup 0.5% hyalase); (3) lidocaine 2% plus epinephrine 1:200 000 (lido 2% epi); or (4) a mixture of lidocaine 2% and bupivacaine 0.5% (2:3 volume per volume mix) containing hyaluronidase 25 i.u. ml-1 (lido/bup/hyalase). A standardized deep peribulbar block technique, akinesia scoring system (each 5 minx4), and supplemental protocol was followed. Onset of block and supplementation rates to achieve akinesia were recorded by a blinded observer; the requirement for augmentation with topical oxybuprocaine or subconjunctival lidocaine during surgery and the time from first PBA injection to the completion of surgery (the duration of surgical access) were also recorded.

RESULTS

Groups (N=50) were comparable. Akinesia scores were similar after each agent at 5 min, better with lido 2% epi compared with bup 0.5% plain at 10 min (P<0.05), and better with bup 0.5% hyalase, lido 2% epi, and lido/bup/hyalase, than with bup 0.5% plain at 15 min (P<0.01, <0.01, <0.05, respectively) and at 20 min (P<0.05, <0.05, <0.025, respectively). The supplementation rate at 5 min was least with lido 2% epi, greater with bup 0.5% plain (P<0.01) and bup 0.5% hyalase (P<0.0005) and greatest with lido/bup/hyalase (P<0.0005), but similar in each group at 10, 15 and 20 min. Overall, those given lido 2% epi required the least number of supplemental injections to achieve globe akinesia. Mean supplemental injectate volumes, augmentation rates during surgery and the durations of surgical access provided by each agent were similar.

CONCLUSION

All four agents provided adequate analgesia during cataract extraction lasting approximately 95-100 min after PBA injection. Lido 2% epi demonstrated most rapid onset and required least number of injections to establish block. A hyaluronidase effect was evident only after 15 min in the bup 0.5% hyalase and lido/bup/hyalase groups. Bup 0.5% plain was overall the least satisfactory, and the greatest supplementation rate occurred with lido/bup/hyalase, suggesting that either lido 2% epi or bup 0.5% hyalase are the most suitable of the agents tested for this type of surgery.

Efficacy of varying concentrations of hyaluronidase in peribulbar anaesthesia

We have compared the efficacy of adding varying concentrations of hyaluronidase to a standard mixture of 2% lidocaine and 1% ropivacaine to provide peribulbar anaesthesia for cataract surgery. We used (i) the time to adequate anaesthesia for surgery and (ii) ocular and eyelid movement scores at 8 min after block as clinical endpoints. Ninety patients were randomly allocated to receive 7-10 ml of equal volumes of 2% lidocaine and 1% ropivacaine without hyaluronidase or with hyaluronidase 15 IU ml(-1) or 150 IU ml(-1). Median time at which the block was adequate for surgery was 6 min in all groups (interquartile range 4-12 min). Median eyelid movement scores were similar in all groups, but the ocular movement scores at 8 min were significantly lower in the group which received hyaluronidase 150 IU ml(-1) than in the group not given hyaluronidase (P<0.03). There were no differences between groups in the incidence of minor complications. A high concentration of hyaluronidase resulted in a statistically significantly lower ocular movement score at 8 min; the clinical relevance of this finding is uncertain.

The methodologic quality of clinical trials on regional anesthesia for cataract surgery

OBJECTIVE

To assess the methodologic quality of published randomized trials of regional anesthesia management strategies for cataract surgery.

DESIGN

Literature review and analysis.

METHOD

We performed a systematic search of the literature to identify all articles pertaining to regional anesthesia for cataract surgery on adults. Overall quality scores and scores for individual methodologic domains were based on the evaluations of two investigators experienced in methodologic research who independently reviewed all relevant articles using a quality abstraction form.

MAIN OUTCOME MEASURES

Study quality in each of five domains: representativeness, bias and confounding, intervention description, outcomes and follow-up, and statistical quality and interpretation.

RESULTS

Eighty-two randomized clinical trials were identified with a mean overall quality score of 44%. The mean domain scores ranged from 37% for representativeness to 58% for outcomes and follow-up. Forty percent or fewer studies received the maximum score for reporting the setting, the population, and the start and end dates; describing the inclusion and exclusion criteria; adequately randomizing subjects; and adequately masking individuals participating in the study. Key outcomes were often inadequately reported, including the distribution of patient-reported pain scores and the mean surgical time.

CONCLUSIONS

Greater attention to methodologic quality and detailed reporting of study results will improve the ability of readers to interpret the results of clinical trials assessing regional anesthesia for cataract surgery.

Clinical efficacy and pharmacokinetics of 1% ropivacaine and 0.75% bupivacaine in peribulbar anaesthesia for cataract surgery

Peribulbar anaesthesia with 1% ropivacaine and 0.75% bupivacaine, both with hyaluronidase, was assessed in a prospective, randomised, double-blind study of 100 patients undergoing cataract surgery. Pharmacokinetic data were obtained from 22 subjects. Akinesia of the globe developed slightly more rapidly in the ropivacaine group, but this difference was only statistically significant at 2 min after injection of the local anaesthetic. Lid akinesia was significantly more complete in the ropivacaine group. There were no differences between the groups with respect to peri-operative analgesia or duration of akinesia. The dose-adjusted maximum concentration of ropivacaine was approximately twice that of bupivacaine with significantly higher values of the area under the concentration-time curves. No drug-related adverse effects were observed. We conclude that there are no clinically significant differences in the quality of the sensory and motor block between 1% ropivacaine and 0.75% bupivacaine when used for peribulbar anaesthesia.

Peribulbar anaesthesia during keratoplasty: a prospective study of 100 cases

AIMS

A prospective study was carried out in order to evaluate the efficacy and safety of peribulbar anaesthesia during keratoplasty and to describe surgical conditions.

METHODS

Of 137 consecutive keratoplasties, 100 (73%) were performed under peribulbar anaesthesia. Patients received a mean volume of 16.5 (SD 4) ml (range 9-22 ml) of a mixture of etidocaine, bupivacaine, and hyaluronidase. Ocular compression duration was at least 20 minutes and intraocular pressure (IOP) was measured with a Tonopen after injection, compression, and before trephination. Degree of akinesia, pain scoring, complications, and surgical conditions were studied.

RESULTS

Before trephination, IOP was 5.73 mm Hg below the preinjection value and was never above 21 mm Hg. Akinesia was complete in 80% of cases and 94% of patients found that surgery was painless. Two patients (2%) were very agitated during surgery. The last patient presented with an acute intraoperative suprachoroidal haemorrhage that did not result in a true expulsive haemorrhage despite an "open sky" situation. Surgical conditions were judged to be optimal by the patients in 92% of cases and by the surgeon in 98% of cases.

CONCLUSION

These results demonstrate that peribulbar anaesthesia offers excellent anaesthesia and akinesia during keratoplasty and may be recommended for this type of surgery.

Is hyaluronidase helpful for peribulbar anaesthesia?

A prospective, randomised controlled study was performed to investigate whether hyaluronidase improved the efficacy of peribulbar anaesthesia. Ninety-two patients undergoing peribulbar anaesthesia for intraocular surgery all received 10 ml of an anaesthetic solution consisting of a 50:50 mixture of 2% lignocaine with 1 in 200,000 adrenaline and 0.5% bupivacaine. Patients were randomised to a hyaluronidase group which received 150 IU/ml hyaluronidase in this anaesthetic solution (a higher concentration than previous studies) or a control group which received no hyaluronidase. There were 44 patients in the hyaluronidase group and 48 patients in the control group. All anaesthetic injections were administered by an experienced ophthalmologist and no supplementary injections were required in any case. The mean time interval between administration of the block and commencement of surgery was 22 minutes. No statistically significant difference was found between the two groups for pre-operative akinesia (p = 0.16), intraoperative akinesia (p = 0.25), eyelid paralysis (p = 0.72), objective analgesia (p = 0.23) or subjective analgesia (p = 0.60). The majority of patients in both groups achieved excellent akinesia, eyelid paralysis and analgesia. The reasons for these findings in the light of previously conflicting reports on the value of hyaluronidase in peribulbar anaesthesia are discussed.

Re-evaluation of hyaluronidase in peribulbar anaesthesia

AIMS/BACKGROUND

Hyaluronidase can augment the actions of local anaesthetics in peribulbar anaesthesia. However, evidence suggests satisfactory anaesthesia can be achieved using mixtures without hyaluronidase. A randomised double blind study was conducted on 50 patients, undergoing peribulbar anaesthesia, to validate this observation.

METHODS

Patients received a standard mixture of local anaesthetic (0.5% bupivacaine and 2% lignocaine in a 1:1 ratio) with or without hyaluronidase (25 IU/ml of mixture), pH values 5.16 and 5.24 respectively. Time taken to establish satisfactory anaesthesia to allow surgery was noted.

RESULTS

The onset time to globe akinesia in the control group ranged from 2 to 15 minutes (mean 5.64 and median 4 minutes) and in the hyaluronidase group from 2 to 12 minutes (mean 4.64 and median 4 minutes). The volume of local anaesthetic injected to achieve satisfactory anaesthesia ranged from 8 to 16 ml (mean 10.96, SD 1.95) in the control group and 10 to 18 ml (mean 11.64, SD 2.8) in the hyaluronidase group. A Mann-Whitney test to compare onset times to globe akinesia between groups gave a p value = 0.6 and 95% confidence interval (-1 to 2 minutes).

CONCLUSION

Addition of 25 IU/ml of hyaluronidase to a standard pH unadjusted local anaesthetic mixture does not significantly reduce the time to the onset of satisfactory globe akinesia.

Peribulbar anaesthesia. A clinical evaluation of two different anaesthetic mixtures

Fifty-four consecutive cases of single injection peribulbar anaesthesia performed by the same ophthalmologist were evaluated concerning clinical effect on motility/akinesia and pain. The patients were randomly selected to one of two different mixtures of anaesthetics, one containing lidocaine, bupivacaine, adrenaline and hyaluronidase. The other lidocaine and bupivacaine. The mixture with adrenalin and hyaluronidase was significantly more effective than the other (success rates of 77.8% and 25.9%, p < 0.005).

The effect of hyaluronidase on peribulbar block

The effect of supplementing a standardised local anaesthetic mixture with hyaluronidase was studied in 60 patients undergoing peribulbar block for intra-ocular surgery. All the patients had the block performed with a 2:1 mixture of lignocaine 2% and bupivacaine 0.75%, but in half of the cases hyaluronidase 50 u.ml-1 was added to the solution by random allocation. The mean volumes of solution injected were 8.9 and 9.0 ml in the control and hyaluronidase groups respectively. Five minutes after injection the block was deemed unsuccessful in one third of the patients in each group and these patients required supplementary injections. At 15 min all but one patient in each group had satisfactory block and these two patients subsequently required retrobulbar block. There were no statistically significant differences between the two solutions in rate of onset of block, requirement for supplementation, block failure, or surgical conditions. There were no significant complications. We conclude that the addition of hyaluronidase 50 u.ml-1 to the local anaesthetic mixture described confers no advantage at the volumes of local anaesthetic used.

Retrobulbar anesthesia with and without hyaluronidase in extracapsular cataract surgery. A prospective, randomized, double-blind study

Eighty patients with senile cataract were subjected to a planned extracapsular cataract extraction (ECCE) with implantation of a posterior chamber intraocular lens. Retrobulbar anesthesia was administered by injection of 4 mg lidocaine 2% with adrenalin. In 40 patients 150 I.U. hyaluronidase (Kinetin) was added to the anesthesia. The hyaluronidase group had a significantly lower frequency of iris prolapse, and deeper anterior chamber, both before and after expression of the lens nucleus. Possible mechanisms explaining the beneficial effect of hyaluronidase in extracapsular cataract surgery are discussed.

Regional anaesthesia for intraocular surgery

The role of anaesthetists in providing local anaesthesia for intraocular surgery has changed over the past decade. No longer confined to the interested few, more and more anaesthetists are involved in monitored care and/or are performing eye block anaesthesia. This review summarizes the information related to eye block anaesthesia. The salient features of the orbital anatomy important for safe conduct of eye block anaesthesia are described. The techniques for retrobulbar and peribulbar anaesthesia, including facial nerve blocks, anaesthetic mixture, types of needles, and softening the eye are presented. Complications such as retrobulbar haemorrhage, globe penetration/perforation, visual impairment, brainstem anaesthesia, muscle injury, and oculocardiac reflex are explored. The implications of anticoagulant therapy are examined. The choice between retrobulbar and peribulbar blocks and the role of anaesthetists are discussed.