Steven Gayer

Regional Anesthesia With Monitored Anesthesia Care for Surgical Repair of Selected Open Globe Injuries

BACKGROUND AND OBJECTIVE To investigate clinical features and visual acuity outcomes associated with the use of regional anesthesia with monitored anesthesia care (RA/MAC) versus general anesthesia for open globe injuries in adult reparable eyes. PATIENTS AND METHODS Retrospective, consecutive case series including all adults with open globe injuries repaired at Bascom Palmer Eye Institute between 2000 and 2003. RESULTS The study included 238 eyes of 238 patients with a median age of 41 years. RA/MAC was employed in 141 (59%) eyes and general anesthesia in 97 (41%) eyes. Patients who had RA/MAC were significantly (P< .001) more likely to have anterior wound location (64% corneal/limbal vs 50%), shorter wound length (6.5 vs 12 mm), and formed anterior chamber (82% vs 56%), and were significantly less likely to have an afferent pupillary defect (12% vs 43%). The improvement from presenting visual acuity to each postoperative follow-up interval was similar for the two groups. CONCLUSIONS RA/MAC is a reasonable alternative to general anesthesia for selected patients with open globe injuries.

Are Ultrasound-Guided Ophthalmic Blocks Injurious to the Eye? A Comparative Rabbit Model Study of Two Ultrasound Devices Evaluating Intraorbital Thermal and Structural Changes

BACKGROUND: Since Atkinsons original description of retrobulbar block in 1936, needle-based anesthetic techniques have become integral to ophthalmic anesthesia. These techniques are unfortunately associated with rare, grave complications such as globe perforation. Ultrasound has gained widespread acceptance for peripheral nerve blockade, but its translation to ocular anesthesia has been hampered because sonic energy, in the guise of thermal or biomechanical insult, is potentially injurious to vulnerable eye tissue. The US Food and Drug Administration (FDA) has defined guidelines for safe use of ultrasound for ophthalmic examination, but most ultrasound devices used by anesthesiologists are not FDA-approved for ocular application because they generate excessive energy. Regulating agencies state that ultrasound examinations can be safely undertaken as long as tissue temperatures do not increase >1.5°C above physiological levels. METHODS: Using a rabbit model, we investigated the thermal and mechanical ocular effects after prolonged ultrasonic exposure to single orbital- and nonorbital-rated devices. In a dual-phase study, aimed at detecting ocular injury, the eyes of 8 rabbits were exposed to continuous 10-minute ultrasound examinations from 2 devices: (1) the Sonosite Micromaxx (nonorbital rated) and (2) the Sonomed VuMax (orbital rated) machines. In phase I, temperatures were continuously monitored via thermocouples implanted within specific eye structures (n = 4). In phase II the eyes were subjected to ultrasonic exposure without surgical intervention (n = 4). All eyes underwent light microscopy examinations, followed at different intervals by histology evaluations conducted by an ophthalmic pathologist. RESULTS: Temperature changes were monitored in the eyes of 4 rabbits. The nonorbital-rated transducer produced increases in ocular tissue temperature that surpassed the safe limit (increases >1.5°C) in the lens of 3 rabbits (at 5.0, 5.5, and 1.5 minutes) and cornea of 2 rabbits (both at 1.5 minutes). A secondary analysis of temporal temperature differences between the orbital-rated and nonorbital transducers revealed statistically significant differences (Bonferroni-adjusted P < 0.05) in the cornea at 3.5 minutes, the lens at 2.5 minutes, and the vitreous at 4.0 minutes. Light microscopy and histology failed to elicit ocular injury in either group. CONCLUSIONS: The nonorbital-rated ultrasound machine (Sonosite Micromaxx) increases the ocular tissue temperature. A larger study is needed to establish safety. Until then, ophthalmic ultrasound-guided blocks should only be performed with ocular-rated devices.

Targeting operating room inefficiencies in the complex management of vision-threatening diseases in children.

OBJECTIVE To review the effect of interventions designed to decrease turnover time in infants and children (median age, 2.6 years; range, 1 month to 10 years) who required examinations under anesthesia. METHODS Five efficiency interventions (3 anesthesia providers for 2 rooms, digital remote communication, change in patient scheduling, standardization of case order, and streamlining administration of preoperative medications) were implemented during a 4(1/2)-year period from January 2003 to July 2007. Using data from our in-house operating room information system, we analyzed turnover times (time it took 1 patient to leave the operating room and the next to enter). RESULTS The mean turnover times decreased from 12.1 minutes to 3.8 minutes. The 90th percentile of longest turnover times decreased from 14.5 minutes in 2003 to 5.8 minutes in 2007, despite a progressive increase in the number of cases per day. CONCLUSION Caring for children who require extensive examinations under anesthesia can be efficiently achieved in nonpediatric environments.

Ultrasound-guided ophthalmic regional anesthesia.

Purpose of reviewNeedle-based and cannula-based eye blocks are ‘blind’ techniques prone to rare but serious complications. Ultrasound, an established adjunct for peripheral nerve block, may be beneficial for ophthalmic anesthesia application. The present review details the evolution of ultrasound-guided eye blocks, outlines safety issues, and reviews recent studies and editorial opinions. Recent findingsUltrasound-assisted ophthalmic regional anesthesia allows imaging of key structures such as the globe, orbit, and optic nerve. Recent findings reveal that needle path is not reliably predictable by clinical evaluation. Needle tips are frequently found to be intraconal, extraconal, or transfixed in the muscle cone independent of the intended type of block. In addition, contemporary human and animal studies confirm that real-time observation of local anesthetic spread inside of the muscle cone correlates directly with block success. SummaryUltrasound-guided ophthalmic regional anesthesia is evolving beyond simple visualization of the anatomy. Recent research emphasizes the imprecision of needle tip location without ultrasound and the key role of imaging local anesthetic dispersion. There is ongoing debate in the literature regarding the utility of routine ultrasound for eye blocks.

Evaluation of distal radial artery cross-sectional internal diameter in pediatric patients using ultrasound

In this study, we measure the radial artery internal diameter (RAID) in children up to 4 years of age before and after the induction of anesthesia. A B‐mode portable color Doppler ultrasound was used to measure the RAID. Three sets of measurements were taken for each child before and after the induction of anesthesia and with the wrist in the neutral and dorsiflexed positions. The reliability of the mean value of the RAID in the three sets in 24 patients was established. There were discrepancies between the RAID and the proposed catheter size in some individuals, which may not only render placement difficult but also have potential for arterial injury. There are good reasons to measure the RAID in small children prior to insertion of an intra‐arterial catheter.

Prone to blindness: answers to postoperative visual loss.

The cumulative impact of case reports, editorials, and collated data from the American Society of Anesthesiologists’ postoperative visual loss (POVL) registry has heightened awareness of an association between proneposition surgery and the woeful phenomena of ischemic optic neuropathy and central retinal vascular occlusion. The American Society of Anesthesiologists has responded by establishing a task force and publishing a practice advisory, both of which have further increased awareness of this issue. The incidence of POVL, however, is exceedingly small and far outweighed by other eye pathologies encountered after non-ocular surgery. In this issue of Anesthesia & Analgesia, Gayat et al. present a case of bilateral acute angle-closure glaucoma in a patient who had undergone spinal surgery, a portion of which was conducted in the prone position. Their report serves as a reminder of other perioperative ocular risks and thus has great value to the journal’s readership. Corneal injuries, secondary to abrasion or exposure, are the most common ocular injuries following non-ophthalmic surgery. Loss of protective corneal reflexes and decreased production of tears during general anesthesia predispose patients to this injury. Less frequently, subconjunctival hemorrhage and chemical injury are causative. In the majority of such instances, a specific source for the abrasion or conjunctivitis cannot be determined. Rare anesthesia-related causes of postoperative visual issues may be encountered in phase I or II recovery areas, or days after surgery. For example, Valsalva retinopathy occurs as a consequence of capillary rupture after precipitous increases in globe venous and intraocular pressure (IOP). Although this may occur spontaneously in healthy individuals, it can arise after coughing and straining upon emergence from anesthesia or after postoperative retching and vomiting. Non-ocular surgery using nitrous oxide, in a patient after recent retinal detachment surgery that involved an injection of intravitreal gas, may increase IOP sufficiently to collapse the central retinal artery. This may result in severe, irreversible visual loss. As with ischemic optic neuropathy, central retinal vascular occlusion, pituitary apoplexy, and cortical blindness, pain is rarely a symptom. The case by Gayet et al. deals with an episode of angle-closure glaucoma. Glaucoma is a sight-threatening condition typically characterized by increased IOP and/or compromised perfusion of the optic nerve. Terminology can be confusing because glaucoma can be classified in several manners: acquired versus congenital, high IOP versus normal or low pressure, acute versus chronic, and open-angle versus narrowor closed-angle. Chronic glaucoma, the most common form, manifests as a painless degradation of peripheral vision. Conversely, acute glaucoma, in which there is an abrupt increase in IOP, presents as a painful eye with potentially compromised visual acuity. The pathophysiology of glaucoma is debated in the ophthalmology literature; it is thought to involve interruption of aqueous humor flow along its route from the ciliary body in the posterior chamber, through the anterior chamber onto the trabecular meshwork and Schlemm’s canal, and ultimately exiting to the systemic venous circulation. Impedance of drainage at the trabecular meshwork produces open-angle glaucoma. Narrow-angle glaucoma, however, occurs when the space between the iris and cornea at the circumferential periphery of the anterior segment diminishes. Some individuals have naturally constricted angles. With age comes physical lens thickening that further restricts the area. Dilation of the pupil by sympatholytic or parasympathomimetic agents increases the girth of the iris, further narrowing the angle. Angle closure occurs when the peripheral iris moves into direct contact with the corneal surface, mechanically obstructing and physically blocking the natural outflow of aqueous fluid. In predisposed individuals, chronic narrow-angle glaucoma may acutely progress to full angle closure. The clinical challenge for the anesthesiologist is to discern whether a painful eye after non-ocular surgery is attributable to corneal abrasion or acute angle-closure glaucoma. This is vital because the latter may be vision threatening and require urgent intervention. Both are typically detected during phase I recovery or within the first 3 hours after surgery. In this case report, the authors postulate that a delayed diagnosis may have resulted from masking of pain by analgesics. Corneal abrasion is often associated with unilateral pain, exacerbated by blinking and eye movement. Most patients From the Departments of Anesthesiology and Ophthalmology, University of Miami Miller School of Medicine, Miami, Florida.

Preoperative Evaluation for Patients With Choroidal/Ciliary Body Melanomas: What Is Necessary?

and com-plications arising from metastatic disease are themost common cause of death. The Collaborative OcularMelanoma Study (COMS) trials were a series of multi-center, randomized clinical studies examining treatmentsfor uveal melanoma. In the COMS, the presence ofmetastatic disease at the time of diagnosis was less than1%.

The use of perioperative antithrombotics in posterior segment ocular surgery.

require serial monitoring of coagulation parameters. 3 Vitreoretinal surgeons are often faced with the dilemma of deciding whether to continue or suspend antithrombotic therapy prior to surgery. Although preoperative discontinuation may diminish the potential for perioperative ocular hemorrhage, it may also increase the probability for systemic complications such as stroke and myocardial infarction. 4‐6 In this regard, it is useful to assign individual patient and procedural risk factors according to a high or low level of risk for thromboembolic complications. 7 Assessment of patient risk factors should be based on an internist’s recommendations and consideration should be given to the underlying condition for which the patient is receiving anticoagulants. For example, patients prophylactically taking antithrombotics for atherosclerosis or a family history of heart disease may be candidates for interval suspension of therapy. Conversely, patients receiving treatment for conditions including the recent placement of a drug-eluting stent, new-onset atrial fibrillation, mechanical heart valves, deep vein thrombosis, or pulmonary embolism may be at substantially greater risk of thrombosis if therapy is interrupted. Hemorrhagic risks associated with vitreoretinal surgery includehyphemaandsubretinal,suprachoroidal,andvitreous hemorrhages. Prevalence of hemorrhagic complications may vary among different systemic conditions and their effect on vitreoretinal anatomy. For instance, a vascular disease such as diabetic retinopathy poses significantly different risks as compared to rhegmatogenous retinal detachment repair. One may logically infer that these complications are more prevalent in patients taking antithrombotic agents; however, thisassumptionisnotconsistentlysupportedbytheliterature. Some studies failed to demonstrate higher rates of intraoperativeorpostoperativebleedinginpatientsreceivinganticoagulants, 8 while another reported the converse. 9 Similarly, platelet inhibition has not been conclusively proven to increase the risk of vitreoretinal surgical bleeding events. The clinical significance of hemorrhage associated with platelet inhibition has, for the greater part, been minimal, with spontaneous resolution and no long-term sequelae. 9‐11 Newer surgical techniques, such as microincisional surgery, and shorter operating times may further reduce the incidence of perioperative bleeding and should diminish the importance attached to discontinuation of antithrombotic therapy. Posteriorsegmentsurgeryismostcommonlyperformedunderregionalanesthesiawithaperibulbarorretrobulbarblock. Hemorrhagic complications associated with these blocks are rare and range from mild periorbital ecchymosis and subconjunctivalhemorrhagetosight-threateningretrobulbarbleeds. The incidence of retrobulbar hemorrhage following an ophthalmic block is exceptionally low 12 and rarely of any long-term adverse functional significance. Although antithrombotics would theoretically be expected to amplify bleeding from a block, there are no evidence-based data to substantiate this; one study found that the risk was the same whether these drugs were held or sustained. 13

Can children undergoing ophthalmologic examinations under anesthesia be safely anesthetized without using an IV line

Purpose: To document that with proper patient and procedure selection, children undergoing general inhalational anesthesia for ophthalmologic exams (with or without photos, ultrasound, laser treatment, peri-ocular injection of chemotherapy, suture removal, and/or replacement of ocular prosthesis) can be safely anesthetized without the use of an intravenous (IV) line. Children are rarely anesthetized without IV access placement. We performed a retrospective study to determine our incidence of IV access placement during examinations under anesthesia (EUA) and the incidence of adverse events that required intraoperative IV access placement. Methods: Data collected from our operating room (OR) information system includes but is not limited to diagnosis, anesthesiologist, surgeon, and location of IV catheter (if applicable), patient’s date of birth, actual procedure, and anesthesia/procedure times. We reviewed the OR and anesthetic records of children (>1 month and <10 years) who underwent EUAs between January 1, 2003 and May 31, 2009. We determined the percentage of children who were anesthetized without IV access placement, as well as the incidence of any adverse events that required IV access placement, intraoperatively. Results: We analyzed data from 3196 procedures performed during a 77-month period. Patients’ ages ranged from 1 month to 9 years. Overall, 92% of procedures were performed without IV access placement. Procedure duration ranged from 1–39 minutes. Reasons for IV access placement included parental preference for antinausea medication and/or attending preference for IV access placement. No child who underwent anesthesia without an IV line had an intraoperative adverse event requiring insertion of an IV line. Conclusion: Our data suggest that for children undergoing general anesthesia for ophthalmologic exams (with or without photos, ultrasound, laser treatment, intraocular injection of chemotherapy, suture removal, and/or replacement of ocular prosthesis), anesthesia can be safely conducted without placement of an IV line.

Succinylcholine for Emergency Airway Rescue in Class B Ambulatory Facilities: The Society for Ambulatory Anesthesia Position Statement.

Procedures in class B ambulatory facilities are performed exclusively with oral or IV sedative-hypnotics and/or analgesics. These facilities typically do not stock dantrolene because no known triggers of malignant hyperthermia (ie, inhaled anesthetics and succinylcholine) are available. This article argues that, in the absence of succinylcholine, the morbidity and mortality from laryngospasm can be significant, indeed, higher than the unlikely scenario of succinylcholine-triggered malignant hyperthermia. The Society for Ambulatory Anesthesia (SAMBA) position statement for the use of succinylcholine for emergency airway management is presented.