Anesthesia for Eye Surgery—The Innate Culture of “1-N-1”



Anesthesia for Eye Surgery—The Innate Culture of “1-N-1”


Amit Sharma MD

Sajeev S. Kathuria MD, FACS




“Indolence is a delightful but distressing state; we must be doing something to be happy”

—Mahatma Gandhi

“What are your concerns during an eye surgery?” we asked the resident. “My attending might walk into the room and catch me snoozing!” was his reply. “What about your anesthesia?” we tried challenging him. “Oh! I will just use my one-and-one,” he said cautiously.

This benign scenario is disturbingly common across the anesthesia community. With the advancement and increasing acceptance of topical and regional techniques, general anesthesia is uncommonly needed for ophthalmic surgeries. Even with regional techniques, the onus of block performance has shifted toward the surgeons, further impeding our involvement in patient care. Under these circumstances, it is not surprising that more and more anesthesia providers dislike working on the “eye surgery” cases, because they all “enjoy” doing the “stuff” and hate just sitting there. Interestingly, there is a lot more to anesthetic care for eye surgeries than just providing 1 mL of midazolam and fentanyl. The purpose of this chapter is to highlight some of these vital issues.

Topical and regional anesthesia seems to be adequate for the majority of eye cases. Most ophthalmic surgeons prefer the quicker recovery with these techniques and do not request “general anesthesia” unless it is necessary. For some cases, however, it is necessary (Table 82.1). It is also occasionally necessary to convert to a general anesthetic in the middle of the procedure. When faced with a request for general anesthesia, junior anesthesia providers sometimes have a tendency to both “oversedate” and “overdebate” before complying with the request. There are several ways to avoid this.

The first step is to make sure that a complete set of intubating and resuscitative drugs is available and readily accessible as well as laryngoscopes and endotracheal tubes.

After that, a little understanding about ocular anatomy helps in predicting cases that may not be effectively covered by available regional techniques. For most ocular surgeries, blocking five cranial nerves (CN II through CN VI) is usually sufficient. CN II (optic nerve) conveys vision; CN III
(oculomotor), IV (trochlear) and VI (abducens) supply the extra-ocular muscles; while the sensory supply of the globe (or eyeball) is mainly from the ophthalmic division of CN V (trigeminal). The periorbital skin (eyelids, eyebrow, forehead, and nose) is supplied by branches of the ophthalmic division of trigeminal nerve and the intraorbital nerve (a division of V2). Most of the extraocular muscles arise from the annulus of Zinn at the orbital apex and insert onto the globe near the corneal limbus. Together they form a conical potential space (annulus or muscle cone) behind the globe that encases the ophthalmic artery, cranial nerves II, III, and the nasociliary branch of the trigeminal nerve. CN IV (the trochlear nerve), which supplies the superior oblique muscle, lies outside the muscle cone.








TABLE 82.1 INDICATIONS FOR GENERAL ANESTHESIA IN OCULAR SURGERIES









































Absolute


1)


Pediatric patients


2)


Uncooperative patients (e.g., those with altered mental status, anxiety, or severe claustrophobia)


3)


Lengthy procedures (>3 hours)


4)


Surgical procedures not adequately covered by regional anesthetic techniques


Relative


1)


Patients with penetrating eye injuries


2)


Patients on anticoagulant therapy


3)


Surgical cases requiring complete ocular akinesia


4)


Patients with a history of nystagmus


5)


Anatomic abnormalities making regional techniques challenging or unsafe


6)


Patient’s or surgeon’s preference


Source: Navaleza JS, Pendse SJ, Blecher MH. Choosing anesthesia for cataract surgery.


Ophthalmol Clin North Am. 2006;19(2):233-237.

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Jul 1, 2016 | Posted by in ANESTHESIA | Comments Off on Anesthesia for Eye Surgery—The Innate Culture of “1-N-1”
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