Ophthalmic Regional Anesthesia Research Articles

Preoperative assessment in ophthalmic regional anaesthesia

Preoperative assessment in ophthalmic regional anaesthesia

Obstructive sleep apnoea syndrome: Ophthalmic anaesthesia perspectives

Summary Obstructive sleep apnoea syndrome (OSAS) is an under diagnosed condition. Although affecting both adults and children, there is a vast dissimilarity in aetiology, pathophysiology and treatment. A mature association with obesity, cardiovascular disease and heart failure predisposes those with the condition to increased peri-operative morbidity. Definitive diagnosis relies on polysomnographic evidence of sleep-disordered breathing while conservative management hinges on weight reduction and nocturnal continuous positive airway pressure therapy (nCPAP). Pre-operative case detection is vital since short term therapy may alleviate co-morbidities. Anaesthetic management focuses on airway control, support of cardiovascular compromise and avoidance of respiratory depressants. Whilst regional anaesthesia remains the preferred technique for ophthalmic surgery; general anaesthesia is employed for children and deserving adults. Both modalities, however, risk airway embarrassment; either an inability to ventilate and control the airway or sedation-induced airway compromise. Moreover, attention is directed at control of intraocular pressure, postoperative airway oedema and effective analgesia. A physician skilled in sedation and regional ophthalmic anaesthesia techniques is essential because incomplete block and unexpected patient movement risk poor visual outcome. Select open globe injuries may be amenable to repair under regional block. Ultimately, favourable outcomes are enhanced by proactive planning, suitable choice of venue and effective interpersonal communication.

Visual experiences during cataract surgery

Recently published literature shows that most patients experience a variety of visual sensations during cataract surgery under local anaesthesia. Most patients (80-100%) retain at least some light perception in the operated eye and many also experience a variety of other visual sensations during cataract surgery under regional ophthalmic anaesthesia (retrobulbar, peribulbar and sub-Tenon's blocks) or topical anaesthesia. The visual sensations experienced include perception of movements, flashes, colours, changes in brightness, or the sight of surgical instruments, the surgeon's hands or fingers, or even the surgeon. These findings are clinically significant because 3-16.2% of patients who had cataract surgery under either regional or topical anaesthesia were frightened by their intraoperative visual experience. Fear and anxiety may cause some patients to become uncooperative during the surgery and may also induce a sympathetic stress response that might cause hypertension, tachycardia with myocardial ischaemia, hyperventilation or an acute panic attack. These effects are especially undesirable as the majority of cataract patients are elderly and have concurrent medical problems. Besides increasing the risk of intraoperative complications, a frightening visual experience may decrease patient satisfaction. Appropriate preoperative counselling has been shown to be effective in reducing the patients' fear. As most patients retain some visual function during cataract surgery under local anaesthesia, anaesthesia providers should be mindful of this phenomenon and offer appropriate preoperative information and counselling to their patients.

Ophthalmic regional anaesthesia

To summarize recent knowledge concerning ophthalmic regional anaesthesia. 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. 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.

Fasting regimens for regional ophthalmic anaesthesia

Members of the British Ophthalmic Anaesthesia Society were surveyed using a postal questionnaire. The response rate was 72.3%. Respondents were asked about starvation before regional anaesthesia for cataract surgery, the use of sedation in these patients, monitoring and if oxygen supplementation was given. The results show that most patients are not starved before this type of regional anaesthesia, and that the majority of patients receive no supplementary sedation or intravenous analgesia. Over 70% of patients received oxygen supplementation.

Complications of Regional Anesthesia.

Assistant ProfessorDepartment of AnesthesiologyHôpital CentralNancy Cedex, France.h.bouaziz@chu-nancy.frComplications of Regional Anesthesia. Edited by Brendan T. Finucane. Philadelphia, Churchill Livingstone, 1999. Pages: 1,332. Price: $50.00.The use of regional anesthetic techniques has greatly increased in recent years and numerous new approaches, especially those for peripheral nerve blocks, have been recently described. Although we know from large surveys that regional anesthesia is safe, complications may occur even in hands of experienced anesthesiologists. To increase knowledge of complications associated with regional anesthesia, a free phone line has been created in France. The principle relies on the constant availability of an expert who responds to questions asked by participants. Our experience with the French system has made us aware of the need for expert advice when addressing complications of regional anesthesia. Therefore, it would seem that a book that aims to address the complications and the adverse reactions that are associated with regional anesthesia is welcome in this context. Is Complications of Regional Anesthesia a worthwhile purchase?Dr. Finucane has brought together an expert group of contributing authors. The 332 pages of this book are organized into 20 chapters, some dealing with complications related to central and peripheral nerve blocks, and others with more specific areas (e.g., complications of pediatric, obstetric, ophthalmic and intravenous regional anesthesia). Moreover, interesting and practical subjects, such as the evaluation of neurologic injury after regional anesthesia, regional anesthesia and infection and regional anesthesia in the presence of neurologic disease, are addressed. Medicolegal aspects and case studies of regional anesthesia are described and discussed.The topics of treatment of local anesthetic toxicity and of postanesthesia nerve injury could have been more complete. Indeed, expert opinion by the authors for these rare problems would have been particularly helpful, given the scant literature that addresses these problems. For example, the importance of a cardiac massage in terms of effectiveness and duration as a means to eliminate bupivacaine from the myocardium during local anesthetic toxicity is not discussed. Also, the possibility of surgical decompression of an injured nerve is not mentioned, though it may be useful, provided that the operation is performed in the first 6 months after nerve trauma. Complications related to peripheral nerve blocks in pediatric anesthesia are not discussed; however, this omission is most likely because of the limited use of peripheral as opposed to central blocks in pediatric practice. Complications associated with the lumbar plexus blocks, aside from those cited in the text, have been reported (e.g., renal subcapsular hematoma, accidental epidural, spinal injection with a posterior approach, catheter knots, epidural injection with a three-in-one block), and recommendations to minimize these complications have been published. These recommendations could have been included in the text.These comments should not detract from the fact that this book is comprehensive and well written. Graphs, tables, drawings, and radiograph imaging (radiographic images in the chapter dedicated to complications of regional anesthesia in chronic pain therapy are small and difficult to read) are used when appropriate. This book may increase our knowledge and improve our therapeutic attitude when facing a complication related to our practice. It could also be used as a handbook to provide a quick, concise, and accurate reference for most issues that are encountered in regional anesthesia. Complications of Regional Anesthesia is a timely publication that specifically addresses the complications related to regional anesthesia. Fortunately, this task has been performed by a team of experts under the supervision of Brendan T. Finucane, and has resulted in a book that should find its place in the library of every anesthesiologist—not only trainees, but also practitioners.

A catheter technique in ophthalmic regional anaesthesia

Regional anaesthesia for ophthalmic surgery is generally accomplished by peri- or retrobulbar techniques. Depending on the duration of ophthalmic surgery, reblock might become necessary. Our goal was to invent a catheter technique for ophthalmic regional anaesthesia that enables the user to administer local anaesthetics intraoperatively into the peri- or retrobulbar space continuously. Twenty-five adult cadaver orbits of normal size and anatomy were used for the experiments. A flexible catheter was introduced transcutaneously or transconjunctivally into the extra- or intraconal space. Methylene blue solution was injected through the catheter. Using the same transcutaneous retro- and peribulbar technique, it was possible to introduce flexible catheters into a proper position of the cadaver orbits. The injected dye was found intra- or extraconally. Examining the spread of the dye in the orbit, we concluded that it is possible to provide ophthalmic anaesthesia for surgery through an indwelling catheter. We proved that continuous or intermittent administration of a local anaesthetic agent into the extra- or inraconal space can be achieved and this technique may allow us to maintain anaesthesia as long as it is necessary.

A catheter technique in ophthalmic regional anaesthesia

Usually general anaesthesia is chosen if ophthalmic surgery of longer duration is expected. Our goal was to introduce a flexible catheter preoperatively into the extra- or intraconal space and to provide sufficient anaesthesia by continuous administration of a local anaesthetic via the catheter. The continuous anaesthetic technique was applied in 28 patients undergoing vitreoretinal surgery. An indwelling catheter was introduced in 20 patients into the intraconal and in 8 patients into the extraconal space. In 6 patients, the position of the catheter was controlled by ultrasound examination prior to the injection of the local anaesthetic agent. For all patients adequate anaesthesia could be achieved and maintained with continuous retrobulbar administration (CRA) of a local anaesthetic by catheter. There were two patients who experienced moderate pain intraoperatively during continuous peribulbar administration (CPA). No complications occurred with the placement of the catheters. The catheter did not disturb the surgeon or the process of the ophthalmic surgery. Continuous administration of a local anaesthetic agent via an indwelling catheter into the intraconal space allowed ophthalmic anaesthesia without time restriction. Thus, CRA is a good alternative to general anaesthesia for patients undergoing long-lasting ophthalmic surgery.

A survey of pre‐operative fasting regimens before regional ophthalmic anaesthesia in three regions of the United Kingdom

A postal and telephone survey of the practice of fasting before regional ophthalmic anaesthesia with and without sedation was sent to 50 hospitals in three regions of the United Kingdom. Responses were received from 100% of hospitals. In most hospitals (58%), local anaesthetic blocks were performed by both surgeons and anaesthetists, with surgeons alone providing ophthalmic anaesthesia in only 14%. Eighty-six per cent of hospitals surveyed had a formal policy regarding pre-operative fasting, with 44% allowing patients to eat and drink freely until their operation. In those hospitals where a fast was imposed, the most common fasting periods were 6 h for food and 2 h for fluids. Twenty-six per cent of respondents would be prepared to give intravenous sedation to a non-fasted patient during eye surgery: small doses of benzodiazepine were the most frequently suggested method. National evidence-based guidelines for ophthalmic regional anaesthesia are needed.

Local anaesthesia for ophthalmic surgery

Local anaesthetic techniques are increasingly popular for ophthalmic surgery. There are few contraindications and the techniques have both a high success rate and a wide margin of safety. However, serious life-threatening complications may occur and it is essential that those involved with the care of these patients have a thorough knowledge of the anatomical, pharmacological and practical aspects of the techniques. This review outlines the relevant anatomy, discusses the commonly used agents and describes current methods of preparation. monitoring and the performance of safe ophthalmic regional anaesthesia.

Regional ophthalmic anesthesia: Safe techniques and avoidance of complications

In the last decade, anesthesiologists have become increasingly involved in administering regional eye blocks, while providing care for patients undergoing ophthalmic surgery. This article describes the two major approaches to regional eye block, namely retrobulbar and peribulbar, with special consideration given to relevant orbital anatomy and technical guidelines. Potential complications, ocular and systemic, with their risk factors, are reviewed. Anesthesiologists wishing to acquire skill in administering safe regional blockade are encouraged to familiarize themselves with regional anatomy and specific guidelines suggested herein.

Comparison of pH-Adjusted Bupivacaine 0.75% and a Mixture of Bupivacaine 0.75% and Lidocaine 2%, Both with Hyaluronidase, in Day-Case Cataract Surgery Under Regional Anesthesia

Alkalinized bupivacaine 0.75% (pH 6.8) and a mixture (1:1) of bupivacaine 0.75% and lidocaine 2%, both with hyaluronidase, were compared in regional ophthalmic anesthesia for day-case cataract surgery. Eighty-two patients were randomized into two groups (n = 39 and 43) to receive one of the two solutions in a double-blind manner. Two intraorbital injections were administered initially: an inferolateral intraconal injection (3 mL) and a medial extraconal injection (3.5 mL). The progress of lid and globe akinesia was examined every 2.5 min up to 25 min and postoperatively. The block was supplemented at 10 and 20 min, if needed. Significantly better globe akinesia was achieved with the bupivacaine-lidocaine mixture; the patients who had received alkalinized bupivacaine needed additional injections significantly more often at 10 and 20 min. In lid akinesia, the onset time and recovery were similar in the two groups. One patient in the alkalinized bupivacaine group felt intraoperative pain, and eight patients in the bupivacaine-lidocaine group and seven in the alkalinized bupivacaine group sensed pain postoperatively from corticosteroid and antibiotic injections. Seventy percent of the pH-adjusted bupivacaine group and 8% of the lidocaine-bupivacaine group had diplopia the day after surgery. Of the two local anesthetic mixtures studied, lidocaine (2%) with bupivacaine (0.75%) provided regional ophthalmic anesthesia of better quality.

Comparison of Regional Ophthalmic Anesthesia Produced by pH-Adjusted 0.75% and 0.5% Bupivacaine and 1% and 1.5% Etidocaine, All with Hyaluronidase

Two concentrations of etidocaine (1 and 1.5%) and of pH-adjusted bupivacaine (0.5 and 0.75%, pH 6.8), all fortified with hyaluronidase, were compared as local anesthetics in regional ophthalmic surgery for cataract extraction. The series comprised 160 patients assigned randomly to four groups (n = 40). Each patient received one of the four anesthetics in a double blind manner. The technique used was an inferolateral intraconal injection (3 mL) followed by a medial extraconal injection (3 mL). Supplemental injections were given at 10 and 20 min, if needed. At 10 min, globe akinesia was satisfactory in both etidocaine groups and in the 0.75% bupivacaine group (78-80% of patients), but in only 37% of the 0.5% bupivacaine group. In lid akinesia, the 0.75% bupivacaine group gained the highest scores, but there was no significant difference between the groups. Perioperative analgesia was better in both bupivacaine groups, in which only 3 and 5 patients felt pain compared to 7 and 12 in the etidocaine groups (P < 0.05). Of these local anesthetics, pH-adjusted 0.75% bupivacaine is recommended for regional ophthalmic anesthesia.

Comparison of Two Needle Lengths in Regional Ophthalmic Anesthesia With Etidocaine and Hyaluronidase

The effect of needle length on the efficacy of regional ophthalmic anesthesia in conjunction with cataract surgery was studied in 97 patients using a two-site injection technique. The local anesthetic used was etidocaine 1.5% with hyaluronidase. In 48 patients, the anesthetic was administered inferolaterally with a 22-millimeter needle, and in the other 49 patients, with a 31-millimeter needle. Every patient had a medial injection with a 12-millimeter needle to achieve lid akinesia and to complete the globe akinesia. At 5 minutes, lid akinesia was considered better in the 22-millimeter needle group (P < .005). After one supplemental dose, when necessary, complete globe akinesia was achieved at 15 minutes significantly more often (94% vs 79%) in the 31-millimeter needle group (P < .05). Lid akinesia in the two groups was identical at that time. Eight patients in the short-needle group and three in the long-needle group experienced some pain during surgery. Throughout the study, the required intraorbital anesthetic volumes were smaller in the 31-millimeter needle group. We recommend the use of a 31-millimeter needle inferolaterally in combination with a 12-millimeter needle medially to achieve satisfactory regional anesthesia for cataract surgery.

Visual evoked potentials after retrobulbar or periocular anaesthesia.

The effect of the local anaesthetic agent, etidocaine, on the optic nerve function was examined at regional ophthalmic anaesthesia. Visual evoked potential (VEP) was recorded before and 15 minutes after injection of the anaesthetic agent in 19 patients scheduled for elective cataract surgery (seven retrobulbar and 12 periocular). Both the anaesthetised--that is, the eye to be operated on--and the fellow eye were examined. In the retrobulbar group, two patients displayed non-recordable VEPs while one had virtually non-detectable waves following the anaesthesia. In two retrobulbarly anaesthetised eyes, later peaks were unidentifiable while two other eyes had decreased amplitudes. In the periocular group, in nine patients, there was no clearcut effect on VEP resulting from the anaesthetic. In three patients of this group mild changes in the anaesthetised eyes were found. The differences in the effect of retrobulbarly or periocularly injected anaesthetics on VEP are probably due to the different concentration of the anaesthetic agent around the optic nerve.