Effect of addition of clonidine to local anaesthetic mixture for peribulbar block

Evaluation of magnesium sulfate as an adjuvant in sub-Tenon anesthesia for cataract surgery: A prospective, randomized controlled trial

Purpose

To evaluate the efficacy, safety, and satisfaction for the use of adjuvant; magnesium sulfate (MgSO4) in sub-Tenon anesthesia for cataract surgery.

Methods

This single centered randomized, double blind trial was held in 2021 after approval of ethical committee at the Eye Hospital, Riyadh, Saudi Arabia. Cataract patients to be operated using local anesthesia were randomly assigned to two groups; Group magnesium sulfate (MS) received 50 mg/0.5 ml of magnesium sulfate and Group normal saline (NS) received 0.5 ml of normal saline added to the standard mixture, respectively. Absence of eyelid dropping and akinesia of the globe at different time after anesthesia were considered as ineffective anesthesia. The age and sex-adjusted generalized estimating equation (GEE) analysis was carried out. Complications, patient's and surgeon's satisfaction were also compared.

Results

Each group had 100 cataract patients. Effectiveness of block was not significantly different in two groups (adjusted odds ratio, 0.90; 95% confidence interval [CI], 0.62, 1.31; P = 0.594). The likelihood of "no eye-opening" significantly increased with time (adjusted odds ratio, 1.26; 95% CI, 1.18-1.34; P < 0.001). Subconjunctival bleeding was significantly higher in the MS versus NS Group (36 of 98 [36.7%] vs. 11 of 102 [10.8%], P < 0.001). Chemosis was not significantly different between the groups (P = 0.95). Patient's satisfaction score was very good (9/10) but slightly higher in NS group than MS (P = 0.001) while surgeon's satisfaction score was similar in both groups (P = 0.149).

Conclusions

Although safe, adding 50 mg of magnesium sulfate did not improve the effect of sub-Tenon anesthesia for cataract surgery. Risk of subconjunctival bleeding was higher in cataract patients operated using MgSO4 compared to those managed with the conventional sub-Tenon anesthetic.

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 review of current ophthalmic anaesthetic practice

INTRO

Ophthalmic surgery ranks among the commonest procedures performed worldwide. This review considers the range of anaesthetic techniques available to the modern ophthalmic anaesthetist, and practical considerations to evaluate in different circumstances. There is a brief summary of the main issues pertaining to the common ophthalmic subspecialties and operations.

SOURCES OF DATA

Pubmed.

AREAS OF AGREEMENT

We present a view of contemporary ophthalmic anaesthetic practice as we see it, both from current UK clinical experience, and the available published evidence.

AREAS OF CONTROVERSY

There is an ongoing debate about the safety of sharp needle blocks (SNBs) compared to subtenons and topical techniques, but SNBs still have a role to play, both in specific cases, and in circumstances where resources are limited.

GROWING POINTS

It remains a challenge to provide safe, cost effective anaesthesia to a growing patient base with ever increasing demands and medical comorbidities. There is a continuing trend towards replacing general with local anaesthesia where possible.

RESEARCH

Research in ophthalmic anaesthesia, as in so many areas, has been plagued by heterogeneity and small studies. A coordinated, large scale, multicentred approach to research questions in future would help to guide best practice with more certainty.

Efficacy and Safety of Magnesium versus Dexmedetomidine as Additives to Local Anesthetic Mixture Using Single Injection Percutaneous Peribulbar Anesthesia in Vitreoretinal Surgeries

Background:

Peribulbar block for vitreoretinal surgery is rather associated with delayed onset of globe anesthesia, akinesia and short duration of analgesia.

Objective:

To compare the effect of addition of Magnesium sulphate vs dexmedetomidine to standard local anesthetics mixtures on the time of onset of Globe Anesthesia, Akinesia & analgesia duration.

Patients and Methods:

Ninety patients of both sexes, aged 25- 75 years, ASA I-III scheduled for vitreoretinal surgery. They were randomly allocated into 3 equal groups each received peribulbar block a mixture of Levo- bupivacaine 0.5% (3 ml) + lidocaine 2% (3 ml) +120 IU hyaluronidase + Control group (C): 0.5 ml of Normal saline. Group (M): 50 mg of Magnesium sulphate in 0.5 ml normal saline. Group (D): 50 μic of dexmedetomidine in 0.5 ml normal saline. The duration of sensory, motor block, Sedation level, Intra-ocular Pressure (IOP) and surgeon satisfaction were assessed.

Results:

The onset of globe anesthesia and akinesia was significantly shorter in M group in comparison with D and C Groups, with a significant increase in the duration of globe analgesia and akinesia in the D Group when compared to both M & C groups. Groups D and M showed a statistically significant decrease in the IOP at 5 min and 10 min when compared to the baseline measurement of the same groups & to C Group, no complications or adverse effects related to the drug or technique were recorded.

Conclusion:

Magnesium sulphate as a local anesthetic adjuvant in peribulbar block is safe and comparable to dexmedetomidine regarding the sensory and motor block duration with better cost-effectiveness and availability.

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.

Effect of Addition of Fentanyl and Clonidine to Local Anesthetic Solution in Peribulbar Block

Objective:

To compare the effect of addition of fentanyl and clonidine as adjuvants to bupivacaine and lignocaine in peribulbar block.

Methods:

The study was conducted on 105 adult patients of either sex, of ASA grade I and II undergoing ophthalmic surgeries. Patients were randomly divided into 3 groups of 35 each. All the patients were given peribulbuar block with 5ml lignocaine 2% +3 ml bupivacaine 0.5% +1 ml hyaluronidase (250 IU). In addition to this 1 ml normal saline was added to Group S, 25 μg fentanyl to Group F and 25 μg clonidine to Group C. Onset and duration of globe and lid akinesia, duration of sensory blockage and analgesia, hemodynamic parameters, number of rescue analgesic and visual analogue score were recorded.

Results:

The mean time of onset of globe and lid akinesia was significantly faster in group F and group C compared to group S, mean duration of globe and lid akinesia was longer in Group F (207.71 + 13.54 and 143.14 + 7.86 min) and group C (213.52 + 14.52 and 162.06 + 17.1 min) compared to group S (117.78 + 10.42 and 87.64 + 9.76 min). The mean duration of analgesia was significantly longer in group F (217.71 + 12.67) and C (258.82 + 14.50 min) as compared to group S (131.39 + 9.63 min).

Conclusion:

Addition of fentanyl or clonidine as adjuvant to local anaesthetic in peribulbar block provides faster onset and prolonged analgesia compared to local anaesthetic alone.

Effect of addition of magnesium to local anesthetics for peribulbar block: A prospective randomized double-blind study

Background:

Magnesium sulphate has been used along with local anesthetics in different regional blocks and found to be effective in decreasing the time of onset of the block and increasing the duration of the block.

Objective:

To evaluate the effect of addition of magnesium sulfate to standard local anesthetics mixture on the time for onset of the globe and lid akinesia for peribulbar block in ophthalmic surgeries.

Materials and Methods:

Sixty patients with American Society of Anesthesiologists status I to III undergoing ophthalmic surgery under peribulbar block were included in this study. Patients were randomized into two groups. Both the groups received 4.5 ml of 2% lidocaine, 4.5 ml of 0.5% bupivacaine with150 IU hyaluronidase. Group NS received normal saline 1 ml in the peribulbar block and Group MS, magnesium sulfate 50 mg in 1 ml normal saline. The onset of akinesia, satisfactory block and complications were observed by an independent observer.

Results:

Demographic data was statistically similar. In the Group NS at 3, 5, 10 and 15 min after the block, complete akinesia was seen in 0, 2, 11 and 28 patients respectively. In the Group MS, at 3, 5, 10 and 15 min after the block, complete akinesia was seen in 13, 23, 27 and 28 patients respectively. Patients received magnesium sulfate showed the statistically significant rapid onset of lid and globe akinesia than the control group till 10 min (P < 0.000). None of the patients needed a supplementary block and had complications during the surgery.

Conclusion:

Addition of 50 mg of magnesium sulfate to the lidocaine-bupivacaine mixture for peribulbar block decreases the onset of akinesia without any obvious side effect.

Effects of dexmedetomidine for retrobulbar anesthesia in orbital ball implants after enucleation surgery

Background:

Dexmedetomidine (DEX) can prolong the duration of local anesthetics, but the use of retrobulbar DEX has not been fully elucidated. This study was designed to determine the effects of adding DEX to lidocaine-bupivacaine for retrobulbar block in orbital ball implants after enucleation surgery.

Materials and Methods:

A total of 200 patients of both sexes aged 30–60 years of American Society of Anesthesiologists I and II, scheduled for orbital ball implants after enucleation surgery, were enrolled for the study. Patients were randomly assigned into one of the two groups: Control (n = 100) received lidocaine-bupivacaine retrobulbar block, DEX (n = 100) received lidocaine-bupivacaine plus 1 ug/kg DEX retrobulbar block. Hemodynamic data, duration of motor and sensory blocks, pain by visual analog scale, bispectral index (BIS), side effects, consumption of dezocine as a rescue analgesic, patient and surgeon satisfaction were recorded.

Results:

Duration of analgesia was prolonged in the DEX, compared with the control group ([258.35 ± 66.82 min] as [130.75 ± 29.52 min], [P < 0.05]). The median number of postoperative analgesic requests per patient during the first 24 h was decreased in the DEX group (P < 0.05). In the first 24 postoperative hours, DEX group consumed significantly less dezocine (P < 0.05). BIS values and mean arterial pressure remained lower in the DEX group, but within the safe range (P < 0.05). The side effect profile was similar between the two groups. Patients and surgeon satisfaction were higher in the DEX group (P < 0.05). Demographic characteristics were comparable in both groups (P > 0.05).

Conclusion:

Retrobulbar DEX reduces consumption of rescue analgesic, prolonged the duration of retrobulbar block, improved postoperative pain, provided better sedation effects, and increased patient and surgeon satisfaction after orbital ball implants after enucleation surgery.

Effect of clonidine added to lidocaine for sub-Tenon's (episcleral) anesthesia in cataract surgery

PURPOSE

We aimed to evaluate the duration of anesthesia, analgesia and ocular akinesia of clonidine added to lidocaine in sub-Tenon's anesthesia in patients undergoing cataract surgery.

METHODS

Forty patients were prospectively enrolled. They were randomized to two sub-Tenon's anesthesia groups: group L (6 ml of lidocaine 2 %, 1 ml of 0.9 % saline and 25 UI/ml of hyaluronidase), and group C (6 ml lidocaine 2 %, clonidine 1 μg/kg, 1 ml of 0.9 % saline and 25 UI/ml of hyaluronidase). Duration of sensory anesthesia, ocular akinesia in all directions, akinesia of the levator palpebrae superioris and orbicularis oculi muscles, the duration of analgesia (time to the first postoperative use of analgesics), the overall use of analgesics and the presence of adverse effects were recorded .

RESULTS

The duration of sensory anesthesia and akinesia of the four rectus, levator palpebrae superioris, and orbicularis oculi muscles was significantly longer in group C (p < 0.05). The number of patients who required analgesics was similar between the groups but the duration of analgesia was longer in group C (p < 0.05). No significant adverse effects were observed.

CONCLUSION

The addition of clonidine 1 μg/kg to 2 % lidocaine in sub-Tenon's anesthesia for cataract surgery increased the duration of sensory anesthesia, ocular akinesia, and the duration of analgesia.

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.

Supplementation of retrobulbar block with clonidine in vitreoretinal surgery: effect on postoperative pain

STUDY OBJECTIVE

To evaluate the effect of clonidine when added to local anesthetics on duration of postoperative analgesia during retrobulbar block.

DESIGN

Prospective, randomized controlled trial.

SETTING

Operating room and Postanesthesia Care Unit of a university-affiliated hospital.

SUBJECTS

80 ASA physical status 1, 2, and 3 patients undergoing vitreoretinal surgery with or without scleral buckling.

INTERVENTIONS

Patients in the control group (n = 40) received a retrobulbar block with 4.5 mL of lidocaine-bupivacaine and 0.5 mL of saline. Clonidine group patients (n = 40) received 4.5 mL of lidocaine-bupivacaine and 0.5 μg/kg of clonidine in a 0.5 mL volume.

MEASUREMENTS

The time to first analgesic request, frequency of postoperative pain, and number of postoperative analgesic requests per patient were assessed.

MAIN RESULTS

37 patients in the control group (92.5%) versus 24 patients (60%) in the clonidine group reported pain postoperatively (P = 0.001), with a shorter time to first analgesic request noted in the control group (4.9 ± 3 vs 11.9 ± 5.3 hrs; P < 0.001). The median number of postoperative analgesic requests per patient during the first 24 hours was higher in the control group than the clonidine group [2 (0-3) vs. 1 (0-3); P < 0.001].

CONCLUSIONS

The addition of clonidine 0.5 μg/kg to the local anesthetics of a retrobulbar block for vitreoretinal surgery decreases the frequency of postoperative pain and prolongs the time of analgesia.

Effect of oral clonidine on acute intraocular pressure rise after phacoemulsification: a prospective double-blind, randomized, clinical trial

OBJECTIVE

To determine the efficacy and safety of oral clonidine in decreasing the prevalence and intensity of postoperative intraocular pressure (IOP) rise in those undergoing phacoemulsification.

METHODS

This was a prospective randomized, double-blind, placebo-controlled, clinical trial including 62 patients (each with 1 affected aye) with senile cataract scheduled for phacoemulsification who were randomly assigned to receive preoperative oral clonidine (5 μg/kg, 31 patients) or placebo (1 tablet, 31 patients). The IOP was measured preoperatively and at 6, 12, and 24 h postoperatively. The prevalence and intensity of the acute postoperative IOP rise was compared between and within the groups.

RESULTS

There was no significant difference between the 2 study groups regarding the baseline characteristics and the baseline IOP (P=0.628). Patients who received placebo as premedication had significantly higher IOP at 6 (17.96±5.49 vs. 13.61±4.09; P<0.001) and 12 (16.90±4.11 vs. 13.96±3.25; P=0.003) h postoperatively compared with those who received oral clonidine. However, there was no significant difference between the 2 groups regarding the IOP at 24 h after operation (15.41±3.96 vs. 16.01±3.41; P=0.0539). The prevalence of acute IOP rise (>21 mmHg) was significantly higher in placebo group compared with clonidine group (25.8% vs. 9.6%; P=0.091).

CONCLUSION

Administering preoperative oral clonidine in a dosage of 5 μg/kg, 2 h before phacoemulsification, significantly decreases the prevalence and intensity of acute postoperative IOP rise in those undergoing general anesthesia. Oral clonidine is safe, cheap, and easily accessible and, thus, it is recommended for controlling the IOP after phacoemulsification, especially in high-risk patients.

Superficial extraconal blockade for vitreoretinal surgery

Context:

Needle length plays an important role for the success of ophthalmic block. The standard practice is to use 25 mm needles length; however, unnecessarily long needles may increase the risk of complications especially in the presence of staphyloma or previous scleral buckle.

Aims:

This work was designed to compare the efficacy of using 15 and 25 mm needle in performing extraconal block for patients undergoing vitreoretinal surgery.

Settings and Design:

Prospective randomized double blinded study.

Materials and Methods:

A total of 120 patients were enrolled in this study and were divided in two groups. In group (1) extraconal block was performed using 25 mm needle, while in group (2) 15 mm needle was used. After primary injection, assessment of the block was done by an anesthesiologist who was unaware of the needle used. If satisfactory akinesia was not achieved a supplementation was provided. At the end of the procedures, patients and surgeons were asked to assess their pain and satisfaction with the anesthetic technique.

Statistical Analysis used:

The sample size calculation using N-Quary version 4. Numerical and categorical data were analyzed using an independent sample, a two-tailed t-test, and chi-square test, respectively.

Results:

The volume of primary injectable was significantly higher in group 2. The two groups were comparable as regards total volume of local anesthetic, supplementation rate, akinesia, pain score, and surgeon satisfaction.

Conclusions:

Using 15 mm needle length to perform extraconal blockade for posterior segment procedures is equally effective to 25 mm needle.

Clinically useful adjuvants in regional anaesthesia

PURPOSE OF REVIEW

In this review, emphasis is placed on adjuvant drugs that are already in clinical use. The list of adjuvants studied during the review period includes adrenaline, clonidine, ketamine, neostigmine, nondepolarizing muscle relaxants, and nonsteroidal antiinflammatory drugs. Some future aspects are considered in a couple of experimental studies on slow-release local anaesthetic formulations.

RECENT FINDINGS

Adrenaline not only acts as a vasoconstrictor, it may also produce analgesia through an alpha2-adrenergic mechanism. Adrenaline may facilitate the uptake of the local anaesthetic into nerves. The addition of adrenaline to a mixture of ropivacaine and fentanyl clearly improves thoracic epidural analgesia. Several recent studies have shown a synergism of clonidine with local anaesthetics in various types of blocks, as well as with spinal opioids. Bradycardia and hypotension may be associated with the use of clonidine. Neostigmine may cause antinociception both in the spinal cord and in peripheral nerves. Neostigmine has been found to potentiate the effect of spinal opioids, but gastrointestinal side effects are frequent. Biodegradable microcapsules containing bupivacaine and dexamethasone have been tested in humans and found to produce analgesia for several days (intercostal block). Local inflammatory reactions and paraesthesias, however, were observed in 30% of cases.

SUMMARY

Adrenaline and opioids may be regarded as the best investigated and most important adjuvants in regional anaesthesia. Other drugs, such as clonidine and neostigmine, may prolong analgesia in various regional anaesthetic techniques, but possible side effects may limit their clinical application. Further development is needed concerning extra-long acting analgesic formulations.

Death potentially secondary to sub-Tenon's block

An 82-year-old ASA 2 patient underwent routine sub-Tenon's block for cataract surgery. One minute after injection of the local anaesthetic, the patient had a generalised tonic-clonic seizure and developed refractory ventricular fibrillation; subsequent resuscitation was unsuccessful. With no evidence for intravascular injection, the lack of structural brain abnormalities, and the most striking feature on post mortem examination being severe triple vessel coronary artery disease, it was concluded that this was primarily cardiac in origin; however, the possibility of brainstem anaesthesia should also be considered.

Brainstem anaesthesia after retrobulbar block: A rare cause of coma presenting to the emergency department

Local anaesthesia, in particular retrobulbar block, is commonly used to perform cataract surgery. Known complications of retrobulbar block include cranial nerve palsies, seizures and cardiorespiratory arrest. We report a case of brainstem anaesthesia causing apnoea and loss of consciousness in a man who received retrobulbar block. The likely mechanism is inadvertent dural puncture of the optic nerve sheath and local anaesthetic injection into the cerebrospinal fluid space. As in this case, the literature reports a short-lived period of anaesthesia with usually no long-term sequelae. Although rare, it is a life-threatening complication if the patient is not appropriately resuscitated. This case highlights the need for trained personnel, with suitable monitoring and adequate resuscitation facilities in order to perform this technique.

Adrenergic regulation of capsaicin-sensitive neurons in dental pulp

Alpha adrenergic agonists (e.g. vasoconstrictors) represent one of the most commonly used drug classes in dentistry. Although adrenergic agonists have potent vascular effects, recent studies suggest that capsaicin-sensitive nociceptors may express adrenoceptors, suggesting that these drugs may directly modulate the function of an important class of pain-signaling neurons in peripheral tissues. In this study, we tested the hypothesis that adrenergic agonists inhibit activation of peripheral terminals of capsaicin-sensitive fibers innervating dental pulp. Pretreatment with epinephrine or clonidine significantly inhibited capsaicin-evoked release of immunoreactive calcitonin gene-related peptide from superfused bovine dental pulp. These studies suggest that adrenergic agonists may reduce postoperative pain in part via a direct inhibition of capsaicin-sensitive nociceptors. This finding may lead to the development of selective, peripherally acting, adrenergic analgesics. Moreover, because neuropeptide release alters blood flow, it is possible that the vascular effects of these drugs are caused by both vasoconstriction and inhibition of peripheral neuropeptide release.