Ophthalmic regional anesthesia: medial canthus episcleral (sub-tenon) anesthesia is more efficient than peribulbar anesthesia: A double-blind randomized study

TRANSCARUNCULAR DOUBLE INJECTION TECHNIQUE FOR PERIBULBAR ANESTHESIA IN VITREORETINAL SURGERY

PURPOSE

Local anesthesia is commonly adopted in vitreoretinal surgery to reach painless and akinesia surgical condition. Currently, peribulbar anesthesia (PBA) and subtenon injection (STN) are the most widely used methods. We propose a transcaruncular double injection peribulbar technique (TRS) and aim to compare it with both standard PBA and STN injections.

METHODS

A total of 105 patients underwent TRS, PBA, or STN. A numerical rating scale was used to assess preoperative, postoperative, and intraoperative pain. Best akinesia score and onset and duration of akinesia were evaluated by two independent graders. The need for supplementary injection was also registered.

RESULTS

TRS group was characterized by a lower intraoperative numerical rating scale variation and absolute numerical rating scale score both at the beginning of surgery ( P 0.046), after 30 minutes ( P 0.032), and at the end of surgery ( P 0.002) compared with the other groups. The TRS group also showed better akinesia score ( P 0.004), fastest onset ( P 0.002), and longer duration ( P 0.042) compared with both PBA and STN. No injection-related complications were reported in the three groups.

CONCLUSION

The newly proposed transcaruncular PBA provided superior pain control and akinesia level with no additional adverse events.

Impact of Video Technology for Improving Success of Medial Canthus Episcleral Anesthesia in Ophthalmology

BACKGROUND AND OBJECTIVES

Efficient learning of regional anesthesia in ophthalmology remains challenging because trainees are afforded limited opportunity to practice ocular anesthesia. The aim of this prospective, randomized, blinded study was to determine whether teaching with video improves regional anesthesia skills of residents in ophthalmology.

METHODS

From January to October 2016, 32 novice anesthesiology residents were evaluated while performing medial canthus episcleral procedures during a 5-day rotation. Residents were randomly assigned to either receive or not receive a video review of their performance at day 3. The primary outcome was a comparison of akinesia using a 12-point scale before incision assessed by the blinded surgeon.

RESULTS

A total of 288 blocks were performed by 32 residents and were assessed by 3 surgeons before the intervention (144 blocks) and after the intervention (144 blocks). Residents in the review group improved to a greater degree compared with residents in the no-review group. The median overall akinesia scores for the review and no-review groups were similarly low (6; interquartile range [IQR], 2-11; and 6 [IQR, 2-9], respectively) on day 1 of the rotation, whereas anesthesia performed by residents in the video group provided a better akinesia score (12 [IQR, 10-12] vs 8 [IQR, 6-10]; P < 0.001) on day 5 of the rotation.

CONCLUSIONS

Video-assisted teaching significantly improves performance of medial canthus episcleral anesthesia performed by novice trainees.

Sub-Tenon's anesthesia for canine cataract surgery

OBJECTIVE

To test a sub-Tenon's anesthesia technique in dogs as an alternative to systemic neuromuscular blockade to aid in canine cataract surgery under general anesthesia.

PROCEDURES

A prospective controlled clinical study was performed involving 12 dogs undergoing bilateral cataract surgery under general anesthesia. One eye was randomly assigned to have phacoemulsification and prosthetic lens implantation performed with sub-Tenon's anesthesia (STA), and the control eye had surgery performed with systemic neuromuscular blockade (NMB). Intraocular pressure (IOP) was measured immediately before and after STA administration. Globe position, globe rotation, pupillary dilation, and vitreal expansion were assessed for both STA and NMB eyes during surgery.

RESULTS

Sub-Tenon's anesthesia produced a globe position suitable for cataract surgery with the degree of vitreal expansion not significantly different to control NMB eyes. STA produced greater anterior globe displacement than NMB in all cases. STA had no significant effect on IOP.

CONCLUSION

Sub-Tenon's anesthesia was an effective alternative to systemic neuromuscular blockade for canine cataract surgery and may be beneficial for surgical exposure in deep orbited breeds.

Lidocaine-Assisted Xylocaine Jelly Anesthesia versus one Quadrant Sub-Tenon Infiltration for Self-Sealing Sclerocorneal Incision Routine Phacoemulsification

Purpose

To compare the effect of Xylocaine jelly and intracameral lidocaine with one quadrant instant sub-Tenon infiltration for self-sealing sclerocorneal phacoemulsification.

METHODS

One hundred patients were enrolled into a prospective randomized study, receiving either a combination of topical 2% Xylocaine jelly and 0.5 ml of intracameral 1% lidocaine or sub-Tenon infiltration with 2 ml of 2% Xylocaine on the operating table. All patients underwent a standard divide and conquer phacoemulsification procedure through a superior sclerocorneal frown incision followed by implantation of a polymethylmethacrylate intraocular lens. Intraoperative pain was indicated by the patient by squeezing the bedside nurse's hand, who allocated it to particular stages of surgery on a chart. After surgery, patients assessed the pain experienced using a 10-unit visual analogue scale.

Results

Pain was indicated on 31 occasions during the operation in the sub-Tenon group (mainly the injection itself) and 67 times in the topical group. The median overall subjective pain score was 3 in the jelly group and 0 in the sub-Tenon. Five eyes (10%) had to be converted to sub-Tenon during the surgery because of intolerable pain.

CONCLUSIONS

Whereas lidocaine supported Xylocaine jelly anesthesia provided acceptable analgesia for 90% of patients operated, sub-Tenon anesthesia proved to deliver better intraoperative comfort in all patients receiving sclerocorneal incision cataract surgery.

The Effect of Sub-Tenon's Bupivacaine on Oculocardiac Reflex during Strabismus Surgery and Postoperative Pain: A Randomized Clinical Trial

PURPOSE

Oculocardiac reflex (OCR), defined as bradycardia induced by manipulation of extraocular muscles, is a serious complication during strabismus surgery for which prevention and proper management is required. In the present study, we investigated the efficacy of sub-Tenon injection of bupivacaine for prevention of OCR and postoperative pain.

METHODS

A prospective randomized controlled clinical trial was conducted. Fifty patients who were candidates for strabismus surgery were randomized into case (sub-Tenon's bupivacaine injection) or control (normal saline injection) groups. Standard strabismus surgery was performed for all cases. Occurrence and severity of OCR (primary outcome) and postoperative pain (using the Visual Analog Scale) were compared between the two groups.

RESULTS

Both incidence (32% vs. 100%; P = 0.002) and severity of OCR (mean heart rate decrease, 10.1 vs. 38.7 beats/minute; P < 0.001) were significantly lower in the study group compared to those in the control group. Postoperative pain scores were significantly lower in the case group than in the control group (mean score, 2.8 vs. 5.9 at 60 minutes after surgery; P < 0.001).

CONCLUSIONS

Sub-Tenon injection of bupivacaine as a local anesthetic can significantly prevent OCR and decrease the severity of bradycardia. This technique can also diminish postoperative pain in patients who underwent strabismus surgery.

Optimal Dose of Dexmedetomidine Retrobulbar Anesthesia during Phacoemulsification Cataract Surgery

Background

The cataract surgery anesthesia should be to make the procedure as safe and as satisfactory as possible for all concerned. The recent progress in anesthesia and surgery now allow cataract extraction to be done with minimal physiological changes to the patient. We aimed in the study to compare between two different doses of dexmedetomidine combined with lidocaine and bupivacaine during retrobulbar anesthesia for cataract extraction by phacoemulsification.

Materials and Methods

This study was done on forty patients with cataract. The patients were enrolled in two groups: Group (A):Twenty patients were received 1.5 ml 2% lidocaine + 1.5 ml 0.5% bupivacaine + 0.25 μg/kg of dexmedetomidine and Group (B): Twenty patients were received 1.5 ml 2% lidocaine + 1.5 ml 0.5% bupivacaine + 0.5 μg/kg of dexmedetomidine.

Results

The globe anesthesia duration, globe, and lid akinesia were significantly longer in the Group B than in the Group A (P < 0.05). Intraocular pressure decreased through the first 15 min after anesthesia in the two groups, and the changes were not significant between the two groups but highly significant in every group when compared to its baseline reading. As regards the conscious level in the two groups, there was a significant difference (P < 0.001). Group A is higher regarding score 2 and 3, and Group B higher in score 4.

Conclusions

We concluded that dexmedetomidine 0.25 μg/kg, when added to retrobulbar block for cataract surgery, will significantly increase the duration of retrobulbar block and improve both the surgeon and the patient satisfaction.

Comparison of Peribulbar with Posterior Sub-Tenon's Anesthesia in Cataract Surgery Among Nigerians

Purpose:

To compare the akinetic and the analgesic effects of peribulbar and posterior sub-Tenon's anesthesia in patients undergoing cataract surgery.

Methods:

In a hospital-based randomized comparative interventional study, patients aged 50 years and above who underwent elective surgery for uncomplicated cataract were randomized to receive either peribulbar block or posterior sub-Tenon block. Pain during injection, surgery, and after surgery was assessed using numerical reporting scale (NRS). Limbal excursion was measured with a transparent meter rule.

Result:

A total of 152 eyes of 152 patients were studied. Peribulbar and sub-Tenon regional blocks provided comparable adequate akinesia (P = 0.06) and similar levels of analgesia (P = 0.10) during cataract surgery. Both techniques also provided similar levels of analgesia to the patient during injection and in the immediate postoperative period. Ninety-two percent of patients who had peribulbar and 97% of those who had sub-Tenon blocks reported either mild pain or no pain at all during surgery (P = 0.49). There was no report of severe pain in all patients during the stages of the surgery. Occurrence of chemosis and subconjunctival hemorrhage was more common in sub-Tenon than peribulbar anesthesia.

Conclusions:

This study shows that peribulbar and posterior sub-Tenon routes of administering anesthetic substances is comparable in providing adequate akinesia and analgesia for cataract surgery with minimal complications. Therefore, both techniques are effective and safe for cataract surgery among Nigerians.

Concise Review: Using Stem Cells to Prevent the Progression of Myopia-A Concept

The prevalence of myopia has increased in modern society due to the educational load of children. This condition is growing rapidly, especially in Asian countries where it has already reached a pandemic level. Typically, the younger the child's age at the onset of myopia, the more rapidly the condition will progress and the greater the likelihood that it will develop the known sight-threatening complications of high myopia. This rise in incidence of severe myopia has contributed to an increased frequency of eye diseases in adulthood, which often complicate therapeutic procedures. Currently, no treatment is available to prevent myopia progression. Stem cell therapy can potentially address two components of myopia. Regardless of the exact etiology, myopia is always associated with scleral weakness. In this context, a strategy aimed at scleral reinforcement by transplanting connective tissue-supportive mesenchymal stem cells is an attractive approach that could yield effective and universal therapy. Sunlight exposure appears to have a protective effect against myopia. It is postulated that this effect is mediated via local ocular production of dopamine. With a variety of dopamine-producing cells already available for the treatment of Parkinson's disease, stem cells engineered for dopamine production could be used for the treatment of myopia. In this review, we further explore these concepts and present evidence from the literature to support the use of stem cell therapy for the treatment of myopia.

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.

Hyaluronidase in sub-Tenon's anesthesia for phacoemulsification, a double-blind randomized clinical trial

AIM

To investigate the effect of hyaluronidase use on the quality of sub-Tenon's anaesthesia for phacoemulsification.

METHODS

This was a randomized, double-blind clinical trial which was conducted at Nikookari Eye Hospital for 5 months. Forty-two eyes of candidates for phacoemulsification under sub-Tenon's anaesthesia were randomly allocated to two equal groups and received either 2 mL of lidocaine 2% solution with (LH), or without (L) addition of hyaluronidase (150IU/mL). Akinesia was assessed 15 minutes after sub-Tenon's injection. Patients and surgeon's satisfaction, as well as the postoperative pain (the visual analogue scale, VAS) were investigated after operation. The contingency tables (including the Chi-square or Fisher's exact tests, when appropriate) and parametric analysis (the independent samples t test) were used for statistical analysis.

RESULTS

Complete akinesia (33.3% vs 4.8%, P=0.04), as well as the patients (85.7% vs 57.1%, P=0.04) and surgeon's satisfaction (87.5% vs 52.4%, P=0.02) were significantly more frequent in LH than in L group. The mean VAS was significantly lower in the same group (1.90±1.45 vs 3.00±1.55, P=0.04).

CONCLUSION

Addition of hyaluronidase to lidocaine solution for sub-Tenon's anesthesia significantly improves the ocular akinesia, enhances the intra-operative patients and surgeons' satisfaction, and attenuates the postoperative pain.

Systematic Review of Peribulbar Anesthesia Versus Sub-Tenon Anesthesia for Cataract Surgery

Commonly used anesthetic techniques for cataract surgery include peribulbar and sub-Tenon anesthesia. This evidence-based review compares these techniques, with a particular focus on patient comfort, akinesia, and anesthetic complications. A systematic search of the literature revealed that there is a paucity of robust evidence comparing sub-Tenon and peribulbar anesthesia. Based on the best available evidence, there is no significant difference in the efficacy of peribulbar compared with sub-Tenon anesthesia for cataract surgery; however, the potential complications of peribulbar anesthesia are more serious.

Anatomy of Tenons capsule

BACKGROUND

  The microscopic and macroscopic anatomy of the anterior and posterior Tenons capsule is described.

METHODS

  An observational anatomic study of twelve orbits of 6 cadavers (mean age 79.5 years) were examined microscopically and 8 orbits of 4 cadavers (mean age 76.8 years) were examined macroscopically. After orbital exenteration, an X-shaped incision was made in the specimens to include the posterior part of the globe. The sections were divided into four parts: superomedial; inferomedial; superolateral; and inferolateral. In the macroscopically examined specimens, the eyelids and globes were removed from the exenterated tissues and the appearance of Tenons capsule was studied.

RESULTS

  In the microscopic study, Tenons capsule covered the sclera beneath the conjunctiva and contained smooth muscle fibres in the anterior area. This anterior fascia, which had a thick appearance, reached the globe equator. From there, the capsule of the orbital fat, which contained no smooth muscle fibres, enveloped the sclera and reached the optic nerve. This was defined as the posterior capsule. In the macroscopic specimens, Tenons capsule had a thick and fibrous white appearance in the anterior area. More posteriorly, the capsule was thinner and more translucent. This thin capsular part was generally larger in the lateral area than in the medial area.

CONCLUSIONS

  Tenons capsule is composed of an anterior thick fibrous tissue comprising the orbital smooth muscle network and the posterior thin fibrous capsule of the orbital fat.

Single-injection percutaneous peribulbar anesthesia with a short needle versus sub-Tenon's anesthesia for cataract extraction

Purpose:

This study compared the efficacy of single-injection percutaneous peribulbar anesthesia (PBA) with a short needle with sub-Tenon's anesthesia (STA) to produce optimal operating conditions for cataract extraction in patients with complicated cataract.

Methods:

Two hundred patients with complicated cataract were enrolled in this prospective, double-blinded, randomized study. Adequate akinesia was a surgical requisite for all cases included in the study because of the expected difficult surgery. The patients were divided into two equal groups to receive either peribulbar anesthesia (PBA) with a 16-mm needle or sub-Tenon's anesthesia. Surgical akinesia (as a primary end point), analgesia, incidence of complications, as well as patient and surgeon satisfaction (as secondary end points) were assessed.

Results:

Both techniques provided similar analgesia during the operation and similar rates of incidence of chemosis with no serious complications; while the PBA group provided higher degree of akinesia 10 minutes after injection of the local anesthetic, a lower incidence of subconjunctival hemorrhage (SCH) and higher patient and surgeon satisfaction compared to the STA group.

Conclusion:

We concluded that when globe akinesia is necessary during surgery, the single-injection technique for percutaneous peribulbar anesthesia with a short needle proved to be more suitable than the STA in providing akinesia for cataract surgery. Also, this PBA technique demonstrated a lower incidence of SCH and was preferred to STA by the patients and surgeon.

Comparison between single-injection inferomedial and inferotemporal peribulbar blockades before cataract surgery

PURPOSE

To compare the efficacy and safety of single-injection inferomedial (IM) and conventional inferotemporal (IT) peribulbar blockades.

PATIENTS AND METHODS

This prospective randomized study included 200 patients who were randomly allocated into two equal groups (n = 100 patients); in the first group, patients received IM peribulbar injection (IM group), while IT peribulbar injection was performed for the second group (IT group). The measurement data were patient characteristics, number of patients who required supplementations, total anesthetic volume injected, surgeon's experience and any recordable complications.

RESULTS

The number of patients who required supplemental anesthetics due to inadequate block was significantly higher in the IT group (15 patients, 15%, vs. no patients, 0%, in the IM group). The total anesthetic volume injected was significantly lower in the IM group (5.6 ± 0.8 vs. 9.8 ± 0.7 ml in the IT group). Surgeon's satisfaction was significantly higher in the IM group (100 vs. 22% in the IT group). The incidences of complications were not significantly different between the two groups.

CONCLUSION

It is safe and effective to conduct single-injection IM peribulbar blockade using a small needle size and low anesthetic volume.

[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.

Efficacy of sub-Tenon's block using an equal volume of local anaesthetic administered either as a single or as divided doses. A randomised clinical trial

Background

Sub-Tenon's anaesthetic is effective and reliable in producing both akinesia and anaesthesia for cataract surgery. Our clinical experience indicates that it is sometimes necessary when absolute akinesia is required during surgery to augment the block with 1–2 ml of local anaesthetic. Hypothesis was that after first injection some of the volume injected may spill out and before second injection the effect of hyaluronidase has taken place and second volume injectate will have desired effect.

Methods

A prospective, randomised, control trial in which patients were randomly allocated to one of two groups. In group 1, single injection of 5 ml of local anaesthetic was injected. In group 2, 3 ml of the same anaesthetic solution was injected followed by application of gentle orbital pressure for 2 minutes. A further 2 ml of the same anaesthetic solution was injected through the same conjunctival incision. Measurement of movement in four quadrants of eye was done by the surgeon at 3 and 6 minutes. Intraocular pressure, chemosis, and subconjuctival haemorrhage were also measured.

Results

Significant differences at 3 minutes between groups for overall movement, medial, superior, and lateral quadrants occurred. At 6 minutes no significant group differences emerged for the overall movement or for any of four quadrants.

Conclusion

Single injection of local anaesthesia for sub-Tenon's block with mixture of lignocaine with adrenaline, bupivacaine and hyaluronidase was found to be superior to provide akinesia of ocular muscles compared to divided dose given by two injections. No difference in groups in terms of haemorrhage, chemosis, patient's satisfaction and intraocular pressure was found.

Trial registration

Trial registration no-ISRCTN73431052

Combined propofol sedation with sub-Tenon's lidocaine/mercaine infusion for strabismus surgery in adults

AIMS

To evaluate the safety and efficacy of propofol sedation combined with sub-Tenon's anaesthesia for strabismus surgery in adults.

METHODS

Thirty-two consecutive patients aged 31-85 years underwent strabismus surgery under general (n=16) or local (n=16) anaesthesia. In the local anaesthesia (study) group, sedation was induced with a loading dose of midazolam, fentanyl, and propofol, followed by continuous infusion of propofol, 3-6 mg/k/h to deep sedation. A nasal tube was inserted to prevent airway obstruction. Sub-Tenon's anaesthesia included infusion of a 3-4 ml mixture (50 : 50) of lidocaine 2%/mercaine 0.5%. General anaesthesia consisted of premedication with midazolam, followed by fentanyl, esmeron-bromate, propofol, and tracheal intubation. Duration of surgery and anaesthesia, intraoperative oculocardiac reflex and arrhythmias, time to discharge, postoperative pain, nausea and vomiting, and patient and surgeon satisfaction were evaluated.

RESULTS

The local anaesthesia group had a significantly shorter operative and anaesthesia time, fewer episodes of oculocardiac reflex or arrythmia/bradycardia requiring treatment, fewer early or late episodes of nausea and vomiting, and less pain. The patients and surgeon in this group reported higher satisfaction.

CONCLUSION

Propofol sedation with local sub-Tenon's injection of lidocaine/mercaine is recommended for the induction and maintenance of anaesthesia during unilateral or bilateral strabismus surgery in adults. The method is quick and effective, without systemic or ocular side effects.

Preoperative Peribulbar Block in Patients Undergoing Retinal Detachment Surgery Under General Anesthesia: A Randomized Double-Blind Study

Retinal detachment surgery is frequently associated with significant postoperative pain and emesis in adults. In this randomized, double-blind, controlled study we sought to demonstrate that 1% ropivacaine peribulbar (PB) block in conjunction with general anesthesia (GA) improves operative conditions and postoperative analgesia compared with GA combined with subcutaneous normal saline injection into the inferior eyelid. Thirty-one patients were included in each group. Anesthesia was performed with target-controlled infusion propofol and continuous remifentanil infusion adjusted to maintain bispectral index values between 40 and 50. Postoperative analgesia included fixed-dose IV infusion of propacetamol and IV injection of nefopam via a patient-controlled analgesia device. Tramadol was infused IV as rescue medication. Demographic data were comparable between the groups and bispectral index values were maintained at the objective target. In the PB group, fewer patients presented an oculocardiac reflex (6 versus 17; P < 0.01); bleeding interfering with the surgical field was reduced (1 versus 11 patients; P < 0.01); mean time to first nefopam request was longer (148 +/- 99 versus 46 +/- 58 min; P < 0.01); mean nefopam consumption was diminished during the first 6 h after tracheal extubation (18.9 +/- 13.9 versus 28.5 +/- 14.7 mg; P < 0.05); immediate postoperative pain scores were lower; and fewer patients required rescue medication (5 versus 23; P < 0.01). The two groups were similar with respect to the incidence of postoperative nausea and vomiting. Overall, PB block combined with GA improved operating conditions and postoperative analgesia in retinal detachment surgery.

A comparison of infero-nasal and infero-temporal sub-Tenon's block

BACKGROUND AND OBJECTIVE

Sub-Tenon's block is usually delivered by the infero-nasal (IN) approach, but occasionally this may not be possible. The infero-temporal (IT) approach has been described, but data is not available on its efficacy.

METHODS

One hundred patients undergoing cataract extraction were randomized to receive an IN or IT sub-Tenon's injection of lidocaine 2% with hyaluronidase 15 IU mL-1. Akinesia was assessed using the Brahma scale at 0, 2, 4, 6 and 8 min. Injection, intraoperative and postoperative pain scores (verbal analogue score, 0-10) were noted, along with the incidence of sub-conjunctival haemorrhage and chemosis.

RESULTS

There were no differences in patient characteristics data, or mean volume of administered local anaesthetic solution (3.3 (SD = 0.4) mL). There were no significant differences between groups in terms of onset of akinesia. Mean akinesia scores at 2, 4, 6 and 8 min were 2.7, 1.1, 0.4 and 0.2 for Group IN, compared to 2.2, 0.9, 0.8 and 0.3 for Group IT. Chemosis occurred in 14 patients in Group IN, compared to 22 in Group IT (P = 0.21).A sub-conjunctival haemorrhage was noted in 14 patients in Group IN and 19 patients in Group IT (P = 0.52). No patients required supplementary injections. Mean pain scores for the injection, intraoperatively and postoperatively were 0.9, 0 and 0 for Group IN, compared to 1.1, 0 and 0 for group IT. The surgeons scored all the blocks as 'good' except for one patient in each group.

CONCLUSIONS

The IT approach provides an equally rapid onset of block, without a significant increase in complications.

Future of regional anaesthesia

The development and refinement of regional anaesthetic techniques for various types of surgery, mainly obstetric, ophthalmic and orthopaedic surgery, and of continuous regional analgesia continues. Suitable analgesic drug mixtures, and concentrations, will be further tested in order to find the ideal analgesic regimen for each type of surgery and for the individual patient. No new local anaesthetics or equipment for clinical use are expected in the near future. Improvement therefore depends much on how the anaesthesiologists use the present drugs, needles, nerve detection devices, catheters and pumps. During training in regional anaesthesia for the speciality of anaesthesiology and intensive care medicine, it may suffice to concentrate only on certain common techniques such as epidural block, spinal block, axillary brachial plexus block, intravenous regional anaesthesia and femoral nerve block. Rare regional anaesthetic blocks and invasive techniques should be mastered and taught by specially trained regional anaesthesiology experts. In chronic pain, regional anaesthetic blocks with local anesthetics are not expected to play any major therapeutic role. However, nerve blocks can be useful for diagnostic purposes and in order to facilitate rehabilitation in chronic pain syndromes.

Peribulbar anesthesia: a percutaneous single injection technique with a small volume of anesthetic

We evaluated the efficacy and safety of a single injection technique with a small volume of anesthetic for ocular peribulbar anesthesia. We included 857 patients undergoing various ophthalmic procedures. Anesthesia consisted of a medial percutaneous injection of 5-6.5 mL of 2% lidocaine. At 2 min 85.6% of the patients had a motor block of at least 50% and at 5 min 78.6% had a motor block >80%. After 5 min 100% of the patients had adequate surgical anesthesia. There were no serious block-related complications. The described technique is a simple and satisfactory alternative to the classical techniques.

Kinetic anaesthesia for laser surgery

PURPOSE

Local anaesthetic is widely used in ophthalmic surgery and more recently in vitreoretinal surgery. Akinesia is a useful effect of local anaesthetic blocks, but there are situations where some residual globe movements are of benefit. We looked to see whether reducing the volume of anaesthetic solution used in a block could retain some kinesia while achieving good analgesia.

METHODS

We compared two groups of patients undergoing panretinal photocoagulation (PRP) with an indirect laser. The control group received 5 ml of anaesthetic solution in a single injection by a standard intraconal technique; a second group received a lower volume of solution by the same technique. We recorded the adequacy of anaesthesia and the amount of residual kinesia for the two groups. Differences between groups were analysed using the Student's t-test and chi(2) tests.

RESULTS

The low-volume group received an average of 2.8 ml, compared to 5 ml in the control group. There was no significant difference in the adequacy of analgesia achieved, however 16/18 (89%: 95% confidence intervals (CI)=81.5-96.3%) of the low-volume group had good perioperative kinesia compared to just 3/21 (14%: 95% CI=6.6-21.9%) of the controls (P<0.001).

CONCLUSIONS

We have shown that low-volume intraconal blocks retain some perioperative kinesia without compromising their analgesic effect.

An audit of peribulbar blockade using 15 mm, 25 mm and 37.5 mm needles, and sub-Tenon's injection*

The efficacy of peribulbar anaesthesia performed with short, medium and long needles, with sub-Tenon's injection as a control, was audited. Two hundred patients undergoing cataract surgery underwent peribulbar injection using 25G needles of the following lengths: 15 mm, 25 mm or 37.5 mm. Sub-Tenon's injections were performed with a curved 25-mm sub-Tenon anaesthesia cannula. The injection technique, ocular akinesia and analgesia scoring system, and supplementary injection protocols were standardised. After initial injections of local anaesthetic via the sub-Tenon's cannula or with 37.5 mm, 25 mm and 15 mm needles, supplementation was required in one (2%), 13 (26%), 22 (44%) and 32 (64%) of patients, respectively; the total number of supplementary injections required were 1, 16, 35 and 47, respectively. It is concluded that the efficacy of peribulbar anaesthesia depends upon the proximity of the deposition of local anaesthetic solution either to the globe or orbital apex. These data justify the classification of peribulbar anaesthesia into: circum-ocular (sub-Tenon's, episcleral), peri-ocular (anterior, superficial); peri-conal (posterior, deep) and apical (ultra-deep) for teaching purposes.

Localization of local anesthetic solution by magnetic resonance imaging

PURPOSE

The aim of this study was to examine the distribution of local anesthetic solution by magnetic resonance imaging (MRI) after combined peribulbar and retrobulbar, superomedial retrobulbar, and sub-Tenon's injection in relation to clinical akinesia.

DESIGN

Randomized clinical trial.

PARTICIPANTS

Fifteen patients scheduled for cataract surgery, 5 patients in each group.

METHODS

Five patients received combined peribulbar and retrobulbar anesthesia, 5 patients received superomedial retrobulbar injection, and 5 patients had sub-Tenon's injection, all with a combination of bupivacaine 0.75%, lidocaine 2%, and hyaluronidase. The MRI scans were performed before the injection and up to 35 minutes after the injection.

RESULTS AND CONCLUSIONS

Reliable anesthesia is achieved using a combined peribulbar and retrobulbar block and a relatively great volume of local anesthetic solution, which spreads throughout the orbit, as evidenced by MRI. After superomedial retrobulbar and sub-Tenon's injection, the local anesthetic solution accumulates behind the globe. Sub-Tenon's injection gives good analgesia and slight akinesia with a very small volume. Superomedial retrobulbar injection and combined peribulbar and retrobulbar block provide a similar degree of exophthalmos, which seems to be the result of the volume injected behind the globe.

[Orbital haemorrhage after medial canthus episclera (sub-Tenon's) anaesthesia]

Medial canthus episclera (sub-Tenon's) anaesthesia is a technique proposed as a suitable alternative to the more classical peribulbar block because of the greater reliability and more constancy in effectiveness. We report two cases of retrobulbar haematoma after sub-Tenon's anaesthesia, one with central retina artery compression needed anterior room punction. Sub-Tenon's anaesthesia, like peribulbar anaesthesia, can give also retrobulbar haemorrhage if the insertion of the needle is not limited to the anterior orbit.

Whatʼs new in ophthalmic anaesthesia?

PURPOSE OF REVIEW

There have been many changes in ophthalmic anaesthesia in the past few years. This review charts recent trends in practice.

RECENT FINDINGS

Topical anaesthesia is gaining widespread use for ophthalmic surgery, but readers need to be aware that definitions vary widely; some 'topical' techniques also include intracameral injections and adjunctive sedation. There is now evidence on the relative effectiveness of different types of local anaesthesia from large systematic reviews. Furthermore, the notion is emerging that the traditional distinction between peribulbar and retrobulbar blocks may not be as clear-cut as previously thought. A new area of investigation is the effect of local blocks on pulsatile ocular blood flow. However, the risk of ocular ischaemia has yet to be quantified. Local anaesthesia has also been tried for posterior segment surgery with apparently successful results. The management of patients taking anticoagulants and anti-platelet agents has been examined, and it appears that there are risks not only in continuing therapy but also in stopping it peri-operatively. The decision thus has to be taken on the balance of risks.

SUMMARY

There have been significant further gains in our understanding of local anaesthetic eye blocks and the management of patients undergoing such procedures.

What is the role of neuromuscular blocking drugs in ambulatory anesthesia?

PURPOSE OF REVIEW

During ambulatory anesthesia, muscle relaxants should be used judiciously because of their impact on operating room efficiency and the potential for morbidity and mortality.

RECENT FINDINGS

Short-acting and low doses of medium-acting muscle relaxants are appropriate for the typically short period of anesthesia required in ambulatory settings, but they are not necessarily indicated. Their adverse effects range from annoying to lethal. Even when the effects are relatively benign, delays may reduce efficiency. Direct laryngoscopy and endotracheal intubation can often safely be accomplished with opioids and propofol, or with topical anesthesia. Procedures such as laparoscopic cholecystectomies can safely be performed with anesthesia via a laryngeal mask airway; with other procedures, a regional technique or monitored anesthesia care is satisfactory. New agents may improve upon currently available muscle relaxants in terms of rapid onset, short duration, and minimal adverse effects.

SUMMARY

Anesthetic and surgical needs should dictate the use of muscle relaxants, and alternatives to their use should be considered.

Anesthesia through a novel retrobulbar catheter provides perioperative pain control for 24 h after pars plana vitrectomy

PURPOSE

The purpose of this study was to assess the retrobulbar catheter technique for perioperative pain control in pars plana vitrectomy.

METHODS

One hundred consecutive pars plana vitrectomies (duration 20-220 minutes) in 88 patients (age range 37-88 years) were performed by the same surgeon under retrobulbar anesthesia using a commercially available retrobulbar needle. Initially, 7 ml of mepivacaine 2% were injected, a 28-gauge flexible catheter was introduced into the retrobulbar space and the needle was withdrawn. The catheter was removed 24 h after surgery. Intraoperatively and postoperatively, the patients were asked to rate pain using a numerical scale from 0 to 10. When pain was more than grade 3, 2 ml of a local anesthetic were re-injected through the catheter.

RESULTS

A first re-injection was given intraoperative/y 53.0 +/- 34.6 minutes after the start of surgery during 35/100 procedures, and second and third injections were needed during 12 /100 and 4/100 procedures, respectively. The first postoperative re-injection was given 3.9 +/- 1.5 hours after the start of surgery in 54 procedures, and second and third injections were carried out in 35/100 and 10/100 procedures respectively.

CONCLUSIONS

The results suggest that a temporary indwelling retrobulbar catheter allows long-lasting titratable local anesthesia during pars plana vitrectomy and titratable postoperative analgesia.

Ophthalmic regional anaesthesia

PURPOSE OF REVIEW

To summarize recent knowledge concerning ophthalmic regional anaesthesia.

RECENT FINDINGS

Ophthalmic regional anaesthesia has changed considerably over the past few years. Alternatives to retrobulbar anaesthesia have been proposed to reduce the number of complications without detriment to efficiency. Finally new local anaesthetics have been adopted and the indications have broadened, especially in vitroretineal surgery.

SUMMARY

New developments in ophthalmic regional anaesthesia are presented in this review. Different methods, indications and side effects are described in order to facilitate the clinician's choice, without any claim to single out an ideal technique.

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.

The effect of sub-Tenon's anaesthesia on intraocular pressure

PURPOSE

To assess the effect of sub-Tenon's anaesthesia on intraocular pressure (IOP) prior to cataract surgery.

METHODS

Fifty consecutive patients undergoing phacoemulsification of cataract were recruited. Routine sub-Tenon's anaesthesia was administered with 5 ml unpreserved 2% lignocaine. IOPs were measured immediately prior to and at 1, 3, 5 and 10 min after injection. Efficacy was assessed subjectively by the operating surgeon. No ocular compression was used. Pre- and post-injection IOPs were compared using the Wilcoxon signed rank test, whereas all other results were compared with baseline using Student's two-tailed paired t-tests.

RESULTS

All patients achieved good analgesia and akinesis. There was no significant difference between the IOP prior to and 1 min after injection. At all time intervals after 3 min there was a significant reduction in IOP compared with the pre-injection measurement. At 5 min, the mean IOP reduction was 2.72 mmHg and at 10 min IOP was lowered by 2.92 mmHg. Both reductions were statistically significant compared with baseline.

CONCLUSIONS

Sub-Tenon's anaesthesia does not cause any significant rise in IOP, thereby possibly making it the anaesthetic technique of choice when an increase in IOP is undesirable. There is no indication for the use of an ocular pressure-reducing device when sub-Tenon's anaesthesia is employed.

Caruncle single injection episcleral (Sub-tenon) anesthesia for cataract surgery: mepivacaine versus a lidocaine-bupivacaine mixture

We compared the quality of anesthesia provided by mepivacaine 2% or a mixture of lidocaine 2%-bupivacaine 0.5%, both with hyaluronidase, in caruncle single-injection episcleral (sub-Tenon) anesthesia. Sixty patients undergoing cataract surgery were included in this randomized, double-blinded study. The time to the onset of blockade, maximal akinesia, need for supplemental injection, and time to recovery were recorded. With mepivacaine, the time to onset was slightly shorter, and the akinesia score higher, than with the mixture. Although statistically significant, these differences are small. With mepivacaine, the time to recovery was shorter. We conclude that the reproducible short duration of the block may be an advantage in outpatient surgery.

IMPLICATIONS

We compared the classic mixture of lidocaine 2% plus bupivacaine 0.5% to mepivacaine 2% for caruncle episcleral (sub-Tenon) anesthesia for cataract surgery. Mepivacaine provided a more efficient block with a quicker onset and a quicker recovery. However, these differences were very small and were of little clinical interest.