Peribulbar anesthesia. Effect of bicarbonate on mixtures of lidocaine, bupivacaine, and hyaluronidase with or without epinephrine

Efficacy of adjuvants in ophthalmic regional anesthesia: A systematic review and network meta-analysis

PURPOSE

This network meta-analysis aims to determine the differences between adjuvants that are used in combination with local anesthetics for ophthalmic regional anesthesia.

DESIGN

Systematic review and network meta-analysis METHODS: A systematic literature search for randomized controlled trials, comparing the impact of adjuvants in ophthalmic regional anesthesia, in Embase, CENTRAL, MEDLINE and Web of Science was performed. Risk of bias was evaluated using the Cochrane risk of bias tool. Frequentist network meta-analysis was performed using a random effects model with saline as the comparator. Primary endpoints were the onset and the duration of sensory block and globe akinesia, as well as the duration of analgesia. Summary measure was the ratio of means (ROM). Secondary endpoints were the rates of side effects and adverse events.

RESULTS

39 trials were identified as eligible for network meta-analysis, including 3046 patients. 17 adjuvants were compared in the most extensive network (onset of globe akinesia). The addition of fentanyl (F), clonidine (C) or dexmedetomidine (D) showed the best overall results. Onset of sensory block: F 0.58 [CI 0.47-0.72], C 0.75 [0.63-0.88], D 0.71 [0.61-0.84], onset of globe akinesia: F 0.71 [0.61-0.82], C 0.70 [0.61-0.82], D 0.81 [0.71-0.92], duration of sensory block: F 1.20 [1.14-1.26], C 1.22 [1.18-1.27], D 1.44 [1.34-1.55], duration of globe akinesia: F 1.38 [1.22-1.57], C 1.45 [1.26-1.67], D 1.41 [1.24-1.59], duration analgesia: F 1.46 [1.33-1.60], C 1.78 [1.63-1.96], D 1.41 [1.28-1.56].

CONCLUSION

The addition of fentanyl, clonidine or dexmedetomidine showed beneficial effects regarding onset and duration of sensory block and globe akinesia.

A Comparative Study to Evaluate the Anesthetic Efficacy of Buffered Versus Non-buffered 2% Lidocaine During Inferior Alveolar Nerve Block

BACKGROUND

The study aimed to compare the clinical efficacy, safety, and acceptability of buffered lidocaine (8.4% sodium bicarbonate and 2% lidocaine with 1:80,000 adrenaline) versus non-buffered lidocaine (2% lidocaine with 1:80,000 adrenaline) during inferior alveolar nerve block.

MATERIALS AND METHODS

Fifty patients who required bilateral extractions in a single arch were included in this study. One hundred extractions were carried out, and all of the patients had nerve blocks during the procedure. We also took note of the patient's pain level as measured on a visual analog scale, as well as the start of the action, duration of postoperative analgesia, and occurrence of any problems. The duration of anesthesia was assessed by the feeling of numbness and the first sign of pain.

RESULT

All the patients in both study groups reported subjective numbness of the lips and tongue. The depth of anesthesia was evaluated by pain and comfort during the procedure with a visual analog scale and showed no significant difference between the two groups. The onset of action for the pterygomandibular nerve block was 1.240.31 minutes (buffered) and 1.710.51 minutes (non-buffered). When compared, the duration of anesthesia was 327.18102.98 minutes (buffered) and 129.0826.85 minutes (non-buffered).

CONCLUSION

This study concludes that the buffered solution has a faster onset of action than the non-buffered solution. Both solutions exhibit similar intraoperative efficacy. The duration of postoperative anesthesia was prolonged with buffering. Buffering also reduced pain scores during the early postoperative period.

A comparative study of sodium bicarbonate and hyaluronidase on pain perception, anesthesia, and akinesia during peribulbar anesthesia for cataract surgery

Background:

An ideal anesthetic solution should provide good anesthesia and akinesia with minimal pain on injection.

Aims:

The aim of this study is to determine the effect on pain perception and efficacy of sodium bicarbonate over hyaluronidase in the local anesthetic mixture during peribulbar anesthesia.

Settings and Design:

A prospective, randomized, double-blind study.

Materials and Methods:

An independent observer labeled two injections as A (hyaluronidase 1500 IU in 30 mL of lignocaine) and B (7.5% sodium bicarbonate 1 mL in 30 mL of lignocaine). Group 1 was injected with injection A while Group 2 was injected with injection B. The visual analog scale (VAS) was used to determine the intensity of pain. Onset and degree of anesthesia and akinesia were recorded.

Statistical Analysis:

Computer software Microsoft Excel SPSS version 26 (Chicago Inc) for windows was used. The qualitative data and quantitative data were reported as proportions and mean ± (standard deviation), respectively. Chi-square test for proportions was used for the comparison of qualitative variables and unpaired Student's t-test was used to test the significance between quantitative variables. P < 0.05 was considered statistically significant. All P were two-tailed.

Results:

Out of 123 patients, 23 were excluded from the study. Hundred patients were divided into Group 1 and Group 2. The mean age in Group 1 was 64.92 ± 10.77 years while in Group 2 was 62.86 ± 11.17 years. The mean heart rate and mean systolic blood pressure in both groups were statistically insignificant. Group 2 experienced very less pain (mean pain score VAS = 5.12 ± 1.17) as compared to Group 1 (mean pain score was 7.16 ± 1.09) and the difference between both the groups was found to be statistically significant. There was a significant difference in the onset of anesthesia in both groups (P = 0.001). In the sodium bicarbonate group, the onset was faster. The onset of akinesia was better in Group 1 (4.76 ± 2.06 min). Grading of akinesia was better in Group 1.

Conclusion:

Sodium bicarbonate reduces pain on injection in peribulbar anesthesia and also results in a quicker onset of anesthesia.

A Prospective, Randomized Double-Blinded Study to Evaluate the Efficacy of Buffered Local Anesthetics in Infected and Inflamed Pulp and Periapical Tissues

Aim

The aim of this study is to evaluate the efficacy of sodium bicarbonate as an additive alkalizing agent to local anesthetic solutions in inflamed and infected pulpal and periapical tissues.

Type of Study

A prospective, randomized crossover double-blinded study was carried out in a university-affiliated hospital in Chennai.

Materials and Methods

A randomized crossover double-blinded study was designed wherein ninety-six patients were enrolled for the study. 1.8 ml of 2% lignocaine with 1:200,000 adrenaline was administered. The latency time period was found to be 5-10 min and extraction was attempted. During extraction, if the patient experienced pain, 0.5 ml of 8.4% sodium bicarbonate was injected into the previously injected local anesthesia site. A time period of 3 min was allowed for the alkalinization to occur. Extraction was carried out only when the patient did not complain of pain. Pain score was assessed before and after administration of 8.4% sodium bicarbonate using visual analog scale. Pulse rate at the baseline, before and after administration of 8.4% sodium bicarbonate, was recorded and the pain scale values were correlated with pulse rate.

Results

It was found that there was a significant decrease in pain after injecting buffered local anesthetics (p < 0.1). Pain score before injecting sodium bicarbonate was higher when compared to post-injection of sodium bicarbonate. There was also significant reduction in pulse rate following the administration of sodium bicarbonate.

Conclusion

Buffered 2% lignocaine with 1:200,000 epinephrine had early onset of anesthesia when compared to unbuffered form. Injecting 2% buffered lignocaine pain was significantly reduced during extraction in the teeth.

Clinical Applications of Hyaluronidase

Hyaluronidases are enzymes that degrade hyaluronic acid, which constitutes an essential part of the extracellular matrix. Initially discovered in bacteria, hyaluronidases are known to be widely distributed in nature and have been found in many classes including insects, snakes, fish and mammals. In the human, six different hyaluronidases, HYAL1-4, HYAL-P1 and PH-20, have been identified. PH-20 exerts the strongest biologic activity, is found in high concentrations in the testicles and can be localized on the head and the acrosome of human spermatozoa. Today, animal-derived bovine or ovine testicular hyaluronidases as well as synthetic hyaluronidases are clinically applied as adjuncts to increase the bioavailability of drugs, for the therapy of extravasations, or for the management of complications associated with the aesthetic injection of hyaluronic acid-based fillers. Further applications in the fields of surgery, aesthetic medicine, immunology, oncology, and many others can be expected for years to come. Here, we give an overview over the molecular and cellular mode of action of hyaluronidase and the hyaluronic acid metabolism, as well as over current and potential future clinical applications of hyaluronidase.

The Efficacy of 0.75% Bupivacaine with ph Adjustment and Hyaluronidase for Peribulbar Blockade: The Incidence of Prolonged Ptosis

A prospective, double masked, randomised study was performed to compare the speed of onset of peribulbar anaesthesia using pH adjusted 0.75% bupivacaine, with and without the addition of hyaluronidase. No significant difference in speed of onset occurred due to the addition of hyaluronidase. There were 7 cases of post operative ptosis in the study group, including 1 case of orbital apex syndrome and 2 cases of transient 3rd nerve palsy. This incidence of post operative ptosis using pH adjusted 0.75% bupivacaine was statistically significantly greater than in a matched control group who received a 50:50 mixture of 1% lignocaine and 0.5% bupivacaine with hyaluronidase (p < 0.05). The possible causes of this increased incidence of post operative ptosis are discussed.

Effect of the addition of rocuronium to 2% lignocaine in peribulbar block for cataract surgery

Background and Aims:

Peribulbar anesthesia is associated with delayed orbital akinesia compared with retrobulbar anesthesia. To test the hypothesis that rocuronium added to a mixture of local anesthetics (LAs) could improve speed of onset of akinesia in peribulbar block (PB), we designed this study. This study examined the effects of adding rocuronium 5 mg to 2% lignocaine with adrenaline to note orbital and eyelid akinesia in patients undergoing cataract surgery.

Material and Methods:

In a prospective, randomized, double-blind study, 100 patients were equally randomized to receive a mixture of 0.5 ml normal saline, 6 ml lidocaine 2% with adrenaline and hyaluronidase 50 IU/ml (Group I), a mixture of rocuronium 0.5 ml (5 mg), 6 ml lidocaine 2% with adrenaline and hyaluronidase 50 IU/ml (Group II). Orbital akinesia was assessed on a 0–8 score (0 = no movement, 8 = normal) at 2 min intervals for 10 min. Time to adequate anesthesia was also recorded. Results are presented as mean ± standard deviation.

Results:

Rocuronium group demonstrated significantly better akinesia scores than control group at 2 min intervals post-PB (significant P value obtained). No significant complications were recorded. Rocuronium added to a mixture of LA improved the quality of akinesia in PB and reduced the need for supplementary injections.

Conclusion:

The addition of rocuronium 5 mg to a mixture of lidocaine 2% with adrenaline and hyaluronidase 50 IU/ml shortened the onset time of peribulbar anesthesia in patients undergoing cataract surgery without causing adverse effects.

Comparison of orbital muscle akinesia caused by rocuronium versus hyaluronidase mixed to the local anesthetic in single injection peribulbar block for cataract surgery

Background:

The aim of this study was to compare orbital muscle akinesia caused by rocuronium versus hyaluronidase when mixed with the local anesthetic in single-injection peribulbar anesthesia (PBA).

Patients and Methods:

Sixty patients were included in the study and subjected to cataract extraction using phacoemulsification technique with intraocular lens implantation. Group I received peribulbar block with 5 ml mixture of 30 IU/ml hyaluronidase and 2% lidocaine. Group II received peribulbar block with 5 ml mixture of rocuronium 5 mg and 2% lidocaine. The onset and duration of akinesia were assessed; the akinesia score at 2, 5, and 10 min was measured after injection. The need for supplementary injection was also recorded.

Results and Conclusion:

PBA using a mixture of rocuronium and lidocaine provides optimal globe akinesia and faster establishment of suitable conditions to start eye surgery and shortens the block onset time as compared with the addition of hyaluronidase to lidocaine.

Effects of local low-dose rocuronium on the quality of peribulbar anesthesia for cataract surgery

OBJECTIVES

Peribulbar anesthesia is associated with delayed and/or incomplete orbital akinesia compared with retrobulbar anesthesia. This study examined the effects of adding rocuronium 5 mg to two different concentrations of lidocaine-bupivacaine mixture on onset time of orbital and eyelid akinesia in patients undergoing cataract surgery.

METHODS

In a double-blind study, 90 patients were equally randomized to receive a mixture of 0.5 ml normal saline, 4 ml lidocaine 2%, and 4 ml bupivacaine 0.5% (group I), a mixture of rocuronium 0.5 ml (5 mg), 4 ml lidocaine 2%, and 4 ml bupivacaine 0.5% (group II), or a mixture of rocuronium 0.5 ml (5 mg), 4 ml lidocaine 1%, and 4 ml bupivacaine 0.25% (group III). Orbital akinesia was assessed on a 0-8 score (0 = no movement, 8 = normal) at 2 min intervals for 10 min. Time to adequate anesthesia was also recorded. Results are presented as mean±SD.

RESULTS

Ocular movement score decreased during the assessment period in all groups. However, at 2 min after block administration, the score decreased to 4±2 (95% CI 3,5) in groups II and III compared with 5±2 (95% CI 4,6) in group I (P<0.01). Time to adequate condition to begin surgery was 9.8±2.9 vs. 6.9±4.1 vs. 7.9±3.9 min for groups I, II, and III, respectively (P=0.01).

CONCLUSION

The addition of rocuronium 5 mg to a mixture of lidocaine 2% and bupivacaine 0.5% shortened the onset time of peribulbar anesthesia in patients undergoing cataract surgery without causing adverse effects.

Sub-Tenon's anesthesia: an update

Sub-Tenon’s block has become the most common technique of orbital regional anesthesia in many centers. It provides effective anesthesia to the orbit with a lower incidence of sight-threatening complications than sharp needle techniques. This article will discuss the relevant anatomy, finer points of sub-Tenon’s block technique, and the evidence supporting its safety.

A prospective, randomized, double-blind study of the anesthetic efficacy of sodium bicarbonate buffered 2% lidocaine with 1:100,000 epinephrine in inferior alveolar nerve blocks

The authors, using a crossover design, randomly administered, in a double-blind manner, inferior alveolar nerve (IAN) blocks using a buffered 2% lidocaine with 1:100,000 epinephrine/sodium bicarbonate formulation and an unbuffered 2% lidocaine with 1:100,000 epinephrine formulation at 2 separate appointments spaced at least 1 week apart. An electric pulp tester was used in 4-minute cycles for 60 minutes to test for anesthesia of the first and second molars, premolars, and lateral and central incisors. Anesthesia was considered successful when 2 consecutive 80 readings were obtained within 15 minutes, and the 80 reading was continuously sustained for 60 minutes. For the buffered 2% lidocaine with 1:100,000 epinephrine/sodium bicarbonate formulation, successful pulpal anesthesia ranged from 10-71%. For the unbuffered 2% lidocaine with 1:100,000 epinephrine formulation, successful pulpal anesthesia ranged from 10-72%. No significant differences between the 2 anesthetic formulations were noted. The buffered lidocaine formulation did not statistically result in faster onset of pulpal anesthesia or less pain during injection than did the unbuffered lidocaine formulation. We concluded that buffering a 2% lidocaine with 1:100,000 epinephrine with sodium bicarbonate, as was formulated in the current study, did not statistically increase anesthetic success, provide faster onset, or result in less pain of injection when compared with unbuffered 2% lidocaine with 1:100,000 epinephrine for an IAN block.

Peribulbar anesthesia for cataract surgery: effect of lidocaine warming and alkalinization on injection pain, motor and sensory nerve blockade

AIM

To compare self-reported pain and efficacy of warmed, alkalinized, and warmed alkalinized lidocaine with plain 2% lidocaine at room temperature for peribulbar anesthesia in cataract surgery.

MATERIALS AND METHODS

Through a prospective, single-blinded, randomized, controlled clinical trial 200 patients were divided into four groups. They received either lidocaine at operating room temperature 18 degrees C, control group (Group C), lidocaine warmed to 37 degrees C (Group W), lidocaine alkalinized to a pH of 7.09+/-0.10 (Group B) or lidocaine at 37 degrees C alkalinized to a pH of 6.94+/-0.05 (Group WB). All solutions contained Inj. Hyaluronidase 50 IU/ml. Pain was assessed using a 10-cm visual analog score scale. Time of onset of sensory and motor blockade and time to onset of postoperative pain were recorded by a blinded observer.

RESULTS

Mean pain score was significantly lower in Group B and WB compared with Group C (P<0.001). Onset of analgesia was delayed in Group C compared with Group B (P=0.021) and WB (P<0.001). Mean time taken for the onset of complete akinesia and supplementation required for the block was significantly lower in Group B. Time of onset of pain after operation was significantly earlier in Group W compared with Group C (P=0.036).

CONCLUSION

Alkalinized lidocaine with or without warming produced less pain than lidocaine injected at room temperature. Alkalinization enhances the effect of warming for sensory nerve blockade, but warming does not enhance alkalinization, in fact it reduces the efficacy of alkalinized solution for blocking the motor nerves in the eye.

[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.

Safety and Efficacy of Sodium Bicarbonate versus Hyaluronidase in Peribulbar Anaesthesia

BACKGROUND

400 cases undergoing surgery for cataract under local anaesthesia were studied. Peribulbar anaesthesia involves injecting a mixture of 2% lignocaine, bupivicaine 0.5% and hyaluronidase into the peripheral space of the orbit through a single infero-lateral point. Sodium bicarbonate has been shown to reduce the time of onset of anaesthesia and pain perception when mixed with local anaesthetics.

METHODS

This study compared two groups of patients (200 each), one receiving hyaluronidase mixed anaesthetic and the other sodium bicarbonate buffered anaesthetic. The groups were compared for effectiveness of the anaesthesia, its onset, duration and the final visual outcome.

RESULTS AND CONCLUSION

Sodium bicarbonate was shown to reduce the time of onset and increase the successful block rate without any adverse affects.

Effect of alkalinization and/or hyaluronidase adjuvancy on a local anesthetic mixture for sub-Tenon's ophthalmic block

BACKGROUND AND OBJECTIVES

pH adjustment and/or addition of hyaluronidase to local anesthetic drugs decrease the time to onset and prolong the duration of regional anesthetic techniques for ocular surgery. The objective of this study was to investigate whether these factors are effective also in sub-Tenon's block.

METHODS

Sixty patients were randomly assigned to four groups in a double blind, prospective fashion, and received 5.125 ml mixtures as follows: 2.5 ml lignocaine 2%, 2.5 ml bupivacaine 0.5% and 0.125 ml isotonic saline (group LB); 2.5 ml lignocaine 2%, 2.5 ml bupivacaine 0.5%, 15 IU hyaluronidase/ml and 0.125 ml isotonic saline (group LBH); 2.5 ml lignocaine 2%, 2.5 ml bupivacaine 0.5% and 0.125 ml sodium bicarbonate 8.4% (group LBpH); and 2.5 ml lignocaine 2%, 2.5 ml bupivacaine 0.5%, 15 IU hyaluronidase/ml and 0.125 ml sodium bicarbonate 8.4% (group LBHpH). This measurement was based on one quadrant sub-Tenon's block. Akinesia was assessed every 30 s.

RESULTS

No statistically significant differences were found between the groups regarding mean times to onset and to complete akinesia. Group LBH displayed a significantly lower frequency of patients experiencing pain and a lower need for rescue medication during surgery than the other groups.

CONCLUSION

pH adjustment and/or addition of hyaluronidase to a mixture of lignocaine and bupivacaine did not shorten the time to onset of akinesia following sub-Tenon's technique. However, the addition of hyaluronidase was associated with a lower fraction of patients experiencing pain during surgery.

Comparison of pH-adjusted bupivacaine with a mixture of non-pH-adjusted bupivacaine and lignocaine in primary vitreoretinal surgery

PURPOSE

To compare the efficacy of alkalinized bupivacaine with that of a mixture of nonalkalinized bupivacaine and lignocaine for local anesthesia in primary vitreoretinal surgery.

METHODS

Through a prospective, double-blind, randomized, controlled clinical trial, 540 consecutive patients undergoing primary vitreoretinal surgery received either alkalinized 0.5% bupivacaine (group B) or a mixture of nonalkalinized 0.5% bupivacaine and 2% lignocaine (group BL), both of which were administered with hyaluronidase, for periocular anesthetic block. The periocular block involved two injections in the extraconal space-one in the lower temporal quadrant and the other in the medial periconal space. The efficacy of the block was graded from 0 to 5 depending on the adequacy of anesthesia and akinesia and the need for local supplementation.

RESULTS

Adequate anesthesia and akinesia (grade 5) were achieved in 72.2% of the patients in group B compared with 57.4% in group BL (P = 0.0003). Intraoperative supplementation was needed in 9.6% and 20.7% of the patients in groups B and BL, respectively (P = 0.0003). Postoperative analgesics were required in 7.4% of the patients in group B and in 15.2% of those in group BL (P = 0.004).

CONCLUSION

Alkalinized 0.5% bupivacaine provides better quality of anesthesia than does the mixture of nonalkalinized 0.5% bupivacaine and 2% lignocaine for patients undergoing primary vitreoretinal surgery.

Carticaine versus lidocaine for peribulbar anesthesia in cataract surgery

PURPOSE

To compare carticaine 4% and lidocaine 2% for peribulbar anesthesia in cataract surgery.

SETTING

Ain Shams and Cairo University Hospitals, Cairo, Egypt.

METHODS

This prospective double-blind randomized study comprised 200 cataract patients assigned to 1 of 2 groups of 100 each based on type of anesthesia: carticaine 4% or lidocaine 2%. The efficacy, safety, and duration of the motor and the analgesic block produced by carticaine 4% adrenaline hyaluronidase mixture and lidocaine 2% adrenaline hyaluronidase mixture used as peribulbar anesthesia were compared. The mean time for satisfactory block, need for supplementary injections, incidence of intraoperative and postoperative pain, and postoperative complications were evaluated. The data were analyzed using the Student t test and Mann-Whitney U test for intergroup differences. The chi-square or Fisher exact test was used to assess eye movement scores, the need for supplementary injections, the onset of postoperative pain, and the incidence of postoperative complications.

RESULTS

The mean time for satisfactory anesthesia was 7.5 minutes +/- 1.68 (SD) for lidocaine 2% and 2.5 +/- 1.53 minutes for carticaine 4% (P <.001). The need for supplementary injections was 28% in the lidocaine group and 4% in the carticaine group (P <.001). The mean onset of postoperative pain was 2.00 +/- 0.86 hours in the lidocaine group and 5.52 +/- 1.80 hours in the carticaine group (P <.05). There were no cases of postoperative neurotoxicity or extraocular muscle dysfunction in either group.

CONCLUSIONS

Carticaine 4% adrenaline hyaluronidase mixture was an effective and safe agent for peribulbar anesthesia. It was more efficient than lidocaine 2% adrenaline hyaluronidase mixture in the onset and quality of anesthesia as well as postoperative analgesia.

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.

Pain perception with pH buffered peribulbar anaesthesia: a pilot study

AIMS

To determine the relation between pH of anaesthetic solutions and patient perception of pain with peribulbar injection of local anaesthesia.

METHODS

This prospective randomised controlled double blind pilot study involved 60 consecutive patients who received a peribulbar block with either a standard acidic local anaesthetic of 5 ml 2% lignocaine and 5 ml of 0.5% bupivacaine (solution A), or an alkalinised solution composed of the same anaesthetic agents but with a pH of 7.44 (solution B). Before surgery patients were asked to grade the pain of both the preoperative dilating drops and the peribulbar injection using a visual analogue scale.

RESULTS

The mean pain scores were similar in the two treatment groups-slightly higher (4.97) in group B who received the buffered solution, compared with group A (4.84) who received the plain solution. The small difference (-0.13, 95% confidence limits -1.6 and +1.3) was not significant. There was, however, a highly significant association between pain threshold ("drop pain") and injection pain levels (p<0.0001).

CONCLUSION

This study showed no difference in the reduction in the pain experienced by patients undergoing peribulbar anaesthesia with pH buffered local anaesthetic. The study suggests the importance of "pain threshold" as a confounder and also showed the considerable pain felt by some patients on instillation of the preoperative dilating drops.

Topical anesthesia with pH-adjusted versus standard lidocaine 4% for clear corneal cataract surgery

PURPOSE

To evaluate and compare the efficacy of a sodium-bicarbonate-adjusted preparation of lidocaine 4% (pH = 7.2) and standard lidocaine (pH = 5.2) for topical anesthesia in clear corneal cataract surgery.

SETTING

Department of Ophthalmology, University of Vienna, Austria.

METHODS

In a prospective, randomized, double-blind clinical trial, clear corneal cataract surgery was performed under topical anesthesia in 44 eyes of 34 patients. In 22 eyes, pH-adjusted lidocaine 4% was administered; in the other 22, standard lidocaine 4%. Aqueous and serum concentrations of lidocaine were measured by high-performance liquid chromatography and ultraviolet detection. Subjective pain was assessed using a visual analog scale of no pain (0%) to worst imaginable pain (100%). On the first postoperative day, visual acuity, intraocular pressure, and corneal staining with fluorescein were examined.

RESULTS

In the pH-adjusted lidocaine group, significantly higher lidocaine concentrations were found in the aqueous humor (15.06 microg/mL +/- 8.2 [SD] versus 4.75 +/- 3.5 microg/mL; P < .0001). In all samples (n = 8), serum lidocaine concentrations were below a minimum detectable level of 0.02 microg/mL. Subjective pain ratings were similar in the pH-adjusted and standard lidocaine groups (mean 9.73 +/- 10.4% and 10.0 +/- 15.4%, respectively). There was no significant between-group difference in intraoperative and postoperative outcomes.

CONCLUSIONS

In this study, pH-adjusted lidocaine 4% was a safe, effective topical anesthetic for clear corneal surgery and had minimal local and systemic toxicity. Administration of pH-adjusted lidocaine 4% resulted in significantly higher aqueous humor lidocaine concentrations than administration of standard lidocaine 4%.

Intravenous sedation prior to peribulbar anaesthesia for cataract surgery in elderly patients

PURPOSE

To investigate if pre-block iv sedation using midazolam, alfentanil, or a midazolam-alfentanil combination minimizes pain, reduces pain recall, and attenuates haemodynamic responses to peribulbar block; and to determine other factors influencing oxygen saturation (SpO2) following iv sedation.

METHODS

In a randomized, double-blind, placebo-controlled study, 120 patients, mean age 73 yr, having cataract surgery with peribular anaesthesia, were randomized to receive either normal saline, 1 mg midazolam, 500 micrograms alfentanil, or 0.5 mg midazolam plus 250 micrograms alfentanil. Blood pressure (BP), heart rate (HR) and pulse oximetry readings were recorded before injection of the study drugs, immediately after completion of the peribulbar block, and 10 min after the block. Pain from the anaesthetic block was assessed immediately after the block and after surgery using a visual analog scale, and recall of pain was assessed by telephone on the day after surgery.

RESULTS

Pain scores were low in all four groups. Midazolam-alfentanil reduced pain perception, and all iv sedation used reduced pain recall. Midazolam reduced systolic BP; alfentanil +/- midazolam reduced HR. All iv sedation reduced SpO2 more than did saline, but not usually to a clinically important level. Nine patients had a SpO2 < or = 90%; all had received alfentanil with or without midazolam. It was not possible to predict oxygen saturation levels by any factors other than iv sedation and baseline SpO2 levels.

CONCLUSION

Intravenous sedation with midazolam or alfentanil or in combination reduced pain perception, pain recall, and haemodynamic responses from peribulbar anaesthesia. Fifteen percent of patients given alfentanil developed clinically important oxygen desaturation. The use of fine gauge needles combined with slow injection of anaesthetic solution causes minimal discomfort, and routine iv sedation may be unnecessary.

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.

The role of hyaluronidase on lidocaine and bupivacaine pharmacokinetics after peribulbar blockade

Orbital regional anesthesia is the only circumstance where hyaluronidase is routinely added to local anesthetics to accelerate the onset of the block. The aim of this study was to compare the pharmacokinetics of lidocaine and bupivacaine with or without hyaluronidase for peribulbar blockade. Twenty-one patients scheduled for cataract surgery with lens implantation were included in this prospective randomized study. Peribulbar blocks were achieved with plain bupivacaine 0.5% (5.5 mL), lidocaine 2% (5.5 mL), and hyaluronidase (100 IU = 2 mL) (n = 10) ir sterile water (2 mL) (n = 11). Plasma bupivacaine and lidocaine concentrations were measured by high-performance liquid chromatography at regular intervals from the end of the local anesthetic injection until the 360th minute. Maximum plasma concentration (Cmax) and time to reach Cmax (Tmax) were obtained for all the patients except one who needed a supplementary injection and was excluded from the study. The time to onset and duration of the analgesia and akinesia were monitored at the times of sampling. Motor blockade was incomplete in two patients in each group without affecting surgery. The Tmax and absorption half-life (t1/2a) of lidocaine and bupivacaine were not different within each group (P > 0.05). The Tmax of lidocaine was shorter in the presence of hyaluronidase (17.1 +/- 2.6 min vs 32.7 +/- 6.0 min) as well as the Tmax of bupivacaine (16.8 +/- 3.0 min vs 26.5 +/- 4.4 min). The Cmax of lidocaine and bupivacaine were not modified by the addition of hyaluronidase. The clearance, terminal half-life, and volume of distribution were not different between groups. The absorption of lidocaine and bupivacaine from the peribulbar space are hastened by the addition of hyaluronidase. The Tmax of lidocaine is not different from that of bupivacaine within each group suggesting that the absorption of local anesthetics is minimally influenced by the liposolubility of the drugs. Moreover, hyaluronidase influences the absorption kinetics of both lidocaine and bupivacaine in the same manner.

The effect of solution temperature on the pain of peribulbar anesthesia

BACKGROUND

Peribulbar anesthesia is the preferred technique of local anesthesia of the majority of cataract surgeons. Local anesthetic injections at other sites in the body have been shown to be less painful if the solution is warmed to body temperature before injection. To determine whether this is of advantage with peribulbar anesthesia, the authors performed a prospective, randomized, single, blind trial comparing local anesthetic injections that have been warmed to room temperature.

METHODS

Forty consecutive patients undergoing routine cataract surgery were randomized into two groups of 20 patients and received local anesthetic at 20 degrees C or 37 degrees C. The peribulbar injection contained a solution of 5 ml 2% Lignocaine, 5 ml 0.5% bupivicaine (Marcaine), and 1550 IU hyaluronidase (HYlase) in a 10-ml syringe on a 25-mm, 25-gauge needle. Seven milliliters of the final solution was injected transcutaneously at the junction of the lateral and medial thirds of the lower lid. The patients graded the pain of the injection using a visual analogue scale.

RESULTS

The pain sensation of local anesthesia is less when the solution is warmed to body temperature compared with room temperature (P = 0.026, using an unpaired Student's t test).

CONCLUSION

Warming the local anesthetic used in peribulbar anesthesia to body temperature before injection reduces this iatrogenic pain significantly.

Investigation of bioequivalence and tolerability of intramuscular ceftriaxone injections by using 1% lidocaine, buffered lidocaine, and sterile water diluents

The pharmacokinetics and tolerability of 1-g doses of ceftriaxone diluted in sterile water, 1% lidocaine, or buffered lidocaine were investigated. No difference in bioequivalence was noted between the three treatments. No difference in peak creatine kinase values was seen. By use of a quantitative pain scale, injection of ceftriaxone with the water diluent was significantly more painful than that with either of the other two diluents. No difference in injection pain was noted for lidocaine or buffered lidocaine.

Efficacy and complication rate of 16,224 consecutive peribulbar blocks. A prospective multicenter study

Although usually safe, retrobulbar anesthesia and peribulbar anesthesia have potentially sight- and life-threatening complications. Although it has been suggested that peribulbar anesthesia is as effective and safer than retrobulbar anesthesia, no large study has addressed the true rate of complications. To determine the efficacy and safety of peribulbar anesthesia, this study prospectively examined 16,224 consecutive peribulbar blocks. Twelve centers in the United States, Germany, and Chile participated in the study. After a peribulbar block was administered, the degree of akinesia, amaurosis, percentage of supplemental blocks required, and side effects and complications occurring after the block and for six weeks were recorded. Perioperative and late optic nerve complications were included. To approximate a real-life situation, ophthalmologists, anesthesiologists, and certified registered nurse anesthetists performed the blocks. Ninety-five percent of patients achieved a 95% or greater degree of akinesia. The incidence of complications in the consecutive cases was low. Orbital hemorrhage occurred in 12 cases (0.74%). There was one globe perforation (0.006%), two expulsive hemorrhages (0.013%), one grand mal seizure (0.006%), and no cases of cardiac or respiratory depression or deaths. Peribulbar is as effective as retrobulbar anesthesia and appears to lead to fewer sight- and life-threatening complications, even when slightly different peribulbar techniques are used. This is especially true when the anesthetic is administered with a 1 1/4-inch or shorter needle with the eye in the primary position, followed by ten to 15 minutes of ocular compression.

Improved peribulbar anaesthesia with alkalinization and hyaluronidase

A prospective double-blind randomized study was carried out to determine the effect of pH and the addition of hyaluronidase to a mixture of lidocaine and bupivacaine on the efficacy of peribulbar anaesthesia. One hundred patients were assigned to one of five groups. All groups received a solution of two parts bupivacaine (0.75%) and one part lidocaine (2%) (with 1:100,000 adrenaline) as the base components of their anaesthesia. Group 1 received only the bupivacaine-lidocaine mixture, pH 3.9. Group 2 received a solution supplemented with hyaluronidase (ten units.ml-1), pH of 5.1. Group 3 received the bupivacaine-lidocaine mixture alkalinized with sodium bicarbonate to a pH of 5.1, the same as solution 2. Group 4 received the mixture with hyaluronidase alkalinized to pH of 6.7. Group 5 received the bupivacaine-lidocaine mixture alkalinized to a pH of 6.7. Efficacy of each block was graded according to the degree of residual movement 30 min following injection, as described by House et al. The solution containing hyaluronidase and pH adjusted to 6.7 was found to be the most effective (P < 0.025). The presence of hyaluronidase without alkalinization did not improve the efficacy of the mixture; and similarly, alkalinization in the absence of hyaluronidase was ineffective. These results reflected the pH- and temperature-dependent thermodynamic properties of local anaesthetics, and the pH-dependent activity of hyaluronidase.

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.

Peribulbar anesthesia. A prospective statistical analysis of the efficacy and predictability of bupivacaine and a lignocaine/bupivacaine mixture

The object of this trial was to determine the efficacy in peribulbar anesthesia of bupivacaine 0.5%, 0.75%, and a combination of bupivacaine 0.5% and lignocaine 2% in equal parts. Fifty-one and 50 patients in random order were injected with 0.5% and 0.75% bupivacaine, respectively, and another 50 patients with the lignocaine/bupivacaine mixture. The results were recorded and all data were statistically analyzed. We concluded that the peribulbar route with the agents used in this trial was not a successful technique. Our criterion for a successful block, i.e., akinesia, was not achieved in more than 54% of cases.

The effects of adrenaline, hyaluronidase and age on peribulbar anaesthesia

In a prospective, randomised, masked trial, 91 patients undergoing intraocular surgery received an anaesthetic mixture containing lignocaine hydrochloride 2% and bupivacaine hydrochloride 0.5%. In addition group 1 had hyaluronidase (50 i.u./ml) and adrenaline (1:200,000), group 2 had hyaluronidase alone, group 3 had adrenaline alone and group 4 had neither. The groups were compared regarding the quality of operating conditions. Hyaluronidase had a substantial beneficial effect though there was no significant difference related to the use of adrenaline. Anaesthesia was less effective in patients under the age of 65 years.