Brain stem anesthesia following retrobulbar block

Complications of ophthalmologic nerve blocks: a review

Complications of ophthalmologic nerve blocks are rare, but they can have serious life- and sight-threatening consequences. Knowledge of the potential complications is essential for the anesthesiologist who performs ophthalmologic nerve blocks. However, most anesthesiologists are unfamiliar with these complications because the majority have been reported in the ophthalmology literature. We review the complications that may occur during the placement of ophthalmologic blocks and their appropriate prompt treatment.

Apnea and seizures following retrobulbar local anesthetic injection

Surgery on the eye is performed using topical anesthesia, retrobulbar anesthesia, peribulbar anesthesia, and general anesthesia. Retrobulbar anesthesia is associated with a number of complications that include apnea (respiratory arrest), seizures, or both. Although these complications are transient and self-limiting, they can be life-threatening if not recognized and treated early. We report two patients who developed apnea, one of whom had cardiorespiratory arrest; and two other patients who presented with seizures. We provided ventilation with 100% oxygen, treated the hypertension with nicardipine, and the tachycardia with esmolol. The patients did not have any residual complications.

Monitored anesthesia care for enucleations and eviscerations

OBJECTIVE

To report the technique and success of using monitored anesthesia care instead of general anesthesia for ocular enucleation and evisceration surgeries.

DESIGN

Retrospective, noncomparative interventional case series.

PARTICIPANTS

Twelve enucleated patients (Soparkar and Patrinely) and 146 eviscerated patients (Kulwin and Kersten).

METHODS

Surgical logs of two oculoplastic practices were reviewed searching for cases of ocular enucleations and eviscerations performed under monitored anesthesia care between 1990 and 2001. Identified hospital and clinic charts were then reviewed.

MAIN OUTCOME MEASURES

Monitored anesthesia care was deemed successful if (1) there were hemodynamic stability and complete analgesia intraoperatively; (2) there was absence of any chart documentation regarding patient or family psychological distress over the anesthesia method used; and (3) patients were discharged from the hospital without the need for observation or treatment > or = 23 hours.

RESULTS

Between 1990 and 2001, 146 eviscerations were performed under local anesthesia with monitored anesthesia care by two surgeons (RCK, DRK) as their routine practice pattern. In 1996, Drs. Soparkar and Patrinely began performing enucleations under monitored anesthesia care in selected cases, and from 1996 to 2001, these surgeons enucleated 12 patients under monitored anesthesia care. Four of the enucleated patients requested surgery without general anesthesia. The remaining eight patients had been refused surgery by at least one other specialist because of the patient's perceived high medical risk for complications under general anesthesia. In all 158 patients, the procedures were deemed successful by the preceding criteria.

CONCLUSIONS

This four-surgeon case series reports the successful use of local anesthesia with monitored care for ocular enucleation and evisceration procedures, offering several potential advantages over the traditional use of general anesthesia.

Pinpoint anesthesia: a new approach to local ocular anesthesia

Current methods of local ocular anesthesia, including retrobulbar, peribulbar, and topical anesthesia, have distinct limitations and many possible, potentially serious complications. We present a new technique that provides rapid, thorough local ocular anesthesia and eliminates these potential complications.

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

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

Respiratory arrest after local anesthesia for outpatient cataract surgery: a dramatic but transient complication

Retrobulbar injection of anesthetic agents is common practice before ophthalmologic procedures. Rare but life-threatening complications of this procedure include respiratory depression and coma. We present the case of a woman with complete respiratory arrest and unresponsiveness who was brought into our emergency department from a local freestanding surgical center after preoperative retrobulbar anesthetic injection. Subsequently, the pathogenesis, clinical features, and supportive treatment for this dramatic but transient complication are discussed.

Regional anaesthesia for intraocular surgery

The role of anaesthetists in providing local anaesthesia for intraocular surgery has changed over the past decade. No longer confined to the interested few, more and more anaesthetists are involved in monitored care and/or are performing eye block anaesthesia. This review summarizes the information related to eye block anaesthesia. The salient features of the orbital anatomy important for safe conduct of eye block anaesthesia are described. The techniques for retrobulbar and peribulbar anaesthesia, including facial nerve blocks, anaesthetic mixture, types of needles, and softening the eye are presented. Complications such as retrobulbar haemorrhage, globe penetration/perforation, visual impairment, brainstem anaesthesia, muscle injury, and oculocardiac reflex are explored. The implications of anticoagulant therapy are examined. The choice between retrobulbar and peribulbar blocks and the role of anaesthetists are discussed.

Peribulbar anesthesia for strabismus surgery

We prospectively studied 76 patients to analyze the effectiveness of peribulbar anesthesia during strabismus surgery. The patients, ranging in age from 14 to 77 years, were given anesthesia with standard preoperative medication and a peribulbar injection of a mixture of 2% mepivacaine hydrochloride and hyaluronidase. Only one of the 76 patients required an additional injection of anesthetic to achieve adequate anesthesia. No morbidity was associated with the peribulbar anesthesia. Local anesthesia, particularly retrobulbar anesthesia, has been used as an alternative technique in an attempt to reduce the morbidity and mortality associated with general anesthesia in ocular surgery, particularly in those patients with high-risk characteristics. Even with retrobulbar anesthesia, however, there is a risk of morbidity and, in rare cases, mortality. Our results suggest that the use of peribulbar anesthesia is a safe and effective means of anesthesia in strabismus surgery because of minimal associated morbidity.

Pharmacokinetics of lidocaine and bupivacaine in retrobulbar and facial block

Analgesia can be obtained during ophthalmic surgery by regional anesthesia using local anesthetic agents. As in other indications, neurological complications may occur, especially because the site of injection is close to the central nervous system. In order to evaluate the risk of retrobulbar and facial block obtained after 40 mg lidocaine and 20 mg bupivacaine injection, pharmacokinetics of both drugs was evaluated in plasma obtained from 11 patients. In addition, 3 cerebrospinal fluid samples were analyzed. Maximal plasma concentration was 0.73 +/- 0.33 micrograms.ml-1 for lidocaine and 0.19 +/- 0.06 micrograms.ml-1 for bupivacaine, obtained 24.7 +/- 23.0 min and 12.0 +/- 3.7 min after the end of injection, respectively. CSF/plasma ratio was in the range 0.05-0.26 for lidocaine and 0.56-1.33 for bupivacaine. In all patients, regional anesthesia was sufficient to perform surgery without any other analgesic drug. No sign of cardiovascular or respiratory toxicity was observed during the study.

Topical anesthesia for strabismus surgery

Twenty-two adults underwent strabismus surgery under topical anesthesia over the past 4 years. Benefits of this technique include avoidance of certain hazards of general and retrobulbar anesthesia, the ability to adjust eye position to the patient's satisfaction on the operative table, and expanded options for patients unwilling to undergo general anesthesia. The major disadvantages are the possibility of increased patient discomfort. Patient selection is important.

Principles of ophthalmic anesthesia

Ophthalmic surgery presents the anesthesiologist with many unique challenges. The exigencies of this subspecialty include a comprehensive knowledge of ocular physiology and pharmacology and an understanding of the anesthetic implications intrinsic to a wide variety of ophthalmic procedures.

Apnoea after retrobulbar block

Two cases of apnoea after retrobulbar block for cataract surgery are described. The possible causes and mechanisms of this complication, its detection and management are discussed.

Shivering following retrobulbar block

A case of a severe but brief period of shivering following a retrobulbar block (RBB) is presented. The shivering occurred within two minutes after completion of the RBB and subsided gradually within five minutes, without specific treatment. The patient remained conscious during the episode of shivering. The shivering was so abrupt and severe as to be misjudged as a seizure, but its onset appeared to be slower than a seizure. The mechanism of shivering appeared to be the central spread of local anaesthetic solution into the brain stem, along the optic nerve. Shivering may be a warning sign of brain stem anaesthesia and demands special care to anticipate life-threatening complications.

Respiratory arrest after retrobulbar block

We describe a patient who suffered respiratory arrest some minutes after retrobulbar block before cataract extraction. She was managed by artificial respiration for 20 min, and after the had recovered from this potentially fatal complication cataract extraction was performed without complications and without any neurological sequelae. Retrobulbar blocks, as well as other retrobulbar, injections, should be performed only in safe situations. Individuals trained in airway maintenance and ventilatory support should be immediately available, and the patient must be monitored for at least 10 min after the retrobulbar injection.

Subarachnoid injection as a complication of retrobulbar anesthesia

We studied eight cases of apparent subarachnoid injection of local anesthetic through the optic nerve sheath and subsequent spread to the parabrainstem cisterns and the contralateral optic nerve sheath. The patients all experienced bilateral decrease in vision and ophthalmoplegia, and variable degrees of central nervous system symptoms and respiratory depression. The complications occurred with a variety of local anesthetic agents and with sharp disposable needles in six of the eight cases. These cases demonstrated the spectrum of signs and symptoms that may follow optic nerve sheath injection of local anesthetic agents.

Life-threatening complication of retrobulbar block. A hypothesis

After routine retrobulbar injection of a 4-ml 1:1 mixture of 0.75% bupivacaine, and of 2% lidocaine and one ampule of hyaluronidase for cataract extraction, the patient sustained bilateral opthalmoplegia, blindness, central respiratory arrest, and loss of consciousness. Neurologic examination shortly thereafter suggests that this may be a result of accidental subarachnoid injection. Prompt recognition and treatment reversed a life-threatening situation.

Respiratory arrest following retrobulbar anesthesia

Respiratory arrest is a serious complication of retrobulbar anesthesia. We have prospectively followed 3123 retrobulbar injections to determine the incidence of respiratory arrest and identify possible risk factors. Injections contained either 2% or 4% lidocaine with 0.75% bupivacaine (Marcaine) in a 50:50 mixture by volume (total 10 cc.) to which a 1 ml ampule of hyaluronidase (150 NF units) was added. Use of 4% lidocaine gave a significantly higher incidence of respiratory arrest than 2% lidocaine (0.79% vs. 0.09%; P = 0.003, Fisher's exact test). Serum levels of lidocaine and bupivacaine of patients who arrested were not elevated significantly compared to 20 control patients. All levels were well below accepted levels of toxicity. Thus, 4% lidocaine increases the risk of respiratory arrest. These results suggest the mechanism is not direct intravascular or central nervous system injection.

Contralateral amaurosis after retrobulbar injection

Contralateral amaurosis after retrobulbar injection of local anesthetic agents occurred in two patients, a 64-year-old woman and a 57-year-old man. The amaurosis resulted from migration of the anesthetic agents to the optic chiasm and contralateral optic nerve via the subarachnoid space. In both cases visual acuity returned to preoperative levels within 90 minutes. A modified technique in which patients look straight ahead or slightly downward and outward during retrobulbar injection, as opposed to the traditional upward and inward positioning of the globe, avoids inadvertent piercing of the sheaths of the optic nerve and injection of substances into the subarachnoid space.

Current concepts in retrobulbar anesthesia

Recently there have been major advances in the field of retrobulbar anesthesia. New agents which allow prolonged anesthesia and akinesia have been introduced. Several new techniques to administer retrobulbar anesthesia have been developed. The toxicity of local anesthetics and the complications arising from such injections have been studied, and ways to avoid and manage them have been expanded.