2   Systemic Complications of Ophthalmic Anesthesia

Although there has been significant growth in the use of topical anesthesia for cataract surgery, the role of anesthesia providers has not diminished.¹ Even under topical anesthesia, the proper preoperative evaluation of the patient, sedation before and during the procedure, and intraoperative monitoring all contribute to the prevention of systemic complications from ophthalmic anesthesia. A full discussion of anesthesia is beyond the scope of this chapter, but a brief overview of systemic complications is presented.

According to several studies, ∼ 90% of cataract patients are over 50 years of age and two thirds are over 65. It is not uncommon to perform such operations on patients over 80 years of age. Therefore, many of the anesthesia considerations are those found in any procedure involving elderly patients. Older patients undergoing ophthalmic surgery frequently have concomitant conditions that should be evaluated preoperatively to determine whether those coexisting conditions are reasonably well controlled prior to surgery.²

Preoperative Evaluation

The preoperative evaluation fulfills several functions. The most important is the medical evaluation of the patient prior to anesthesia and surgery. Another is reducing anxiety by informing the patient about the procedure and administering preoperative medications. Both the medical evaluation and preoperative sedation contribute to preventing systemic complications in patients having ophthalmic surgery.

The requirements of the preoperative history and physical examination are variable. The history includes the major anatomic and physiological systems, all medications, drug allergies, previous surgical procedures, and any complications related to prior anesthetics. The cardiovascular history, including previous myocardial infarction, congestive heart failure, strokes, or hypertension, is particularly important. A history of pulmonary diseases, including asthma or severe chronic obstructive pulmonary disease (COPD), diabetes mellitus, hepatic insufficiency, or renal disease is also important. Each of these has implications for the administration of the anesthesia or potential complications that may occur.

It is also important that the anesthesia provider conduct a preanesthesia physical exam. This does not substitute for a complete physical exam by the patient’s internist or other primary care provider, but can be used to assess whether the patient may safely undergo the anesthesia provided for the surgical procedure. The physical exam includes auscultation of the heart and lungs, an evaluation of the airway, and any abnormal system suggested by the patient’s history.

Unlike in the past, there is no prescribed list of laboratory tests that all patients undergo prior to surgery. Testing is now

individualized to the patient’s underlying medical history. Diabetics should have a finger-stick blood sugar level performed immediately prior to surgery to determine the patient’s current blood sugar levels. A hemoglobin A1_c level is very useful to assess the long-term control, but this does not provide information on the current blood sugar level and should not substitute for a finger-stick test on the day of surgery. Patients on digitalis or diuretics should have a recent potassium level, and Coumadin users should have a prothrombin time/partial thromboplastin time (PT/PTT) done prior to surgery, especially if a peri/retrobulbar block is used as the anesthesia. Other tests may be indicated depending on the patient’s history.

A recent electrocardiogram (ECG) is indispensable in patients with a known history of cardiac disease or diabetes mellitus, which may mask the existence of severe cardiac disease. Studies vary widely as to what percentage of patients have unknown cardiac disease discovered on a routine preoperative ECG, and some anesthesia providers obtain a recent ECG in all patients over 50 years of age. Others take a slightly different approach. They obtain a preoperative ECG on patients with a cardiac history or asymptomatic patients with at least one risk factor on the Revised Cardiac Risk Index (RCRI), but forgo ECG exams in asymptomatic patients with no RCRI risk factors. RCRI risk factors include cerebrovascular disease, congestive heart failure, ischemic cardiac disease, diabetes mellitus, or a creatinine level greater than 2.0 mg/dL.

Once the preoperative evaluation is complete, an intravenous (IV) line is started and the patient is placed on monitors, including an ECG, blood pressure cuff, and pulse oximeter. These monitors are sufficient in the freestanding ambulatory surgery center or hospital outpatient surgery department. If the patient requires more extensive monitoring, the surgery should be done in a hospital setting.

The patient is given preoperative antianxiety medications, most commonly a combination of fentanyl (narcotic) and midazolam (benzodiazepine). The usual dose is 1 cc fentanyl (50 µg) and 1 mg midazolam, although this should be reduced by half in frail, elderly patients. This combination produces a relaxed, but not overly sedated patient within 2 to 3 minutes. If a patient remains anxious, a second dose may be given after ∼ 5 minutes. Antiemetics are not usually necessary for outpatient ophthalmic surgery. However, if a patient has a history of severe nausea and vomiting after surgery, an antiemetic medication can be added.

Occasionally a patient will have elevated blood pressure even after the premedications are given. This can be treated with a rapid-acting antihypertensive agent. Commonly used agents include IV labetalol, hydralazine, esmolol, or sublingual nifedipine. The blood pressure should be closely monitored, but surgery can proceed safely once the blood pressure is controlled.

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