Ophthalmic Surgery – General Considerations

What the Anesthesiologist Should Know before the Operative Procedure

As a group, patients undergoing ophthalmic surgery have a low risk of developing perioperative cardiac complications, but frequently have associated medical conditions associated with the extremes of age. Nitrous oxide (N2O) can increase intraocular pressure and cause blindness in patients who recently had a medical gas injected into the eye (a treatment for retinal detachment). To avoid this complication, N2O should not be used for patients who have had SF6 injected within the previous 4 weeks or C3F8 injected within the previous 3 months.

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

Most ophthalmic operations are elective. As a general rule medical conditions should be optimized before ophthalmic surgery.

Emergent: Chemical burn, central retinal artery occlusion, and acute glaucoma (unresponsive to medication) are ophthalmic emergencies and require operations as soon as possible to improve the chance of maintaining vision in the affected eye.

Urgent: Ruptured globe is considered an urgent case. Surgery should generally be performed within 24 hours of injury to reduce the chance of endophthalmitis from developing. Detached retinas are also considered to require urgent repairs if the macula is attached to the retina. In this situation surgery is usually performed within 24 hours of the diagnosis to reduce the risk of the macula detaching. (Macular detachment is associated with a poorer visual outcome.) However, surgery for a ruptured globe or a detached retina can generally be delayed until acute medical conditions are optimized.

Elective: Most other eye operations are elective and can be delayed if necessary until the patient is optimized for surgery.

2. Preoperative evaluation

The goals of a focused history and physical (H&P) are to establish a good doctor-patient relationship, assess patient risks, psychologically and physically prepare the patient for surgery, inform the patient about the risks and benefits of anesthesia, document this informed consent, assist in ensuring the correct site is operated upon, and plan for perioperative management. A good H&P will reduce the risk of perioperative delay, cancellation, and optimize perioperative care.

Medical conditions should be optimized before elective ophthalmic surgery. Medical problems frequently encountered in adults include hypertension, diabetes, use of antithrombotic agents, coronary artery disease, congestive heart failure, COPD, arrhythmias, and implanted cardiac devices. Infants and children frequently present with complications of prematurity and congenital abnormalities.

“Routine” preoperative labwork and electrocardiography (ECG) has not been shown to improve perioperative outcome (at any age) for low-risk surgery. Therefore, preoperative labwork and ECG are only warranted for specific medical conditions. Although there are guidelines, currently there are no nationally agreed upon preoperative lab recommendations. The guidelines we use at our institution (Massachusetts Eye & Ear Infirmary) for low-risk surgery include electrolytes for diuretic use, preoperative blood sugar for diabetics, and repeat blood sugar(s) for insulin-dependent diabetics on the day of surgery, INR for patients who took warfarin within 4 days or less before surgery, BUN/creatinine for renal dysfunction, LFTs, CBC, PT/INR, PTT for severe liver disease, and ECG for patients with cardiac disease.

Because most eye operations are elective, most medically unstable conditions should be optimized before surgery.

Delaying surgery may be indicated if the patient has acute respiratory illness, hypertension that is unevaluated or unresponsive to medication (systolic BP>180, diastolic BP>110), exacerbation of COPD or CHF, or a new clinically signficant arrhythmia.

3. What are the implications of co-existing disease on perioperative care?

b. Cardiovascular system

Acute/unstable conditions

Acute or unstable cardiac conditions should generally be stabilized before eye surgery.

Baseline coronary artery disease or cardiac dysfunction

Goals of management are to minimize stress responses (e.g., tachycardia, hypertension) and maintain cardiovascular stability.

Perioperative evaluation

A focused history is the most important method for detecting cardiovascular diseases. A preoperative ECG may be useful (as a baseline) for patients with known or suspected cardiac disease but most patients with stable cardiovascular disease can undergo ophthalmic surgery without other specialized cardiac testing. Delaying surgery or requesting additional preoperative evaluation for cardiac conditions is indicated for unstable cardiac conditions, such as MI within 30 days (7 days if additional myocardium shown not to be at risk), unstable angina, unstable CHF, unstable severe arrhythmias, and, if general anesthesia is required, undiagnosed murmurs. Other unstable cardiovascular conditions such as recent CVA or TIA may also warrant delaying surgery and obtaining additional medical evaluation.

Hypertension (HTN) is a common problem in the elderly. The goal is to maintain the patient’s blood pressure (BP) in their therapeutic range such as systolic BP (SBP) <180 and diastolic BP (DBP) <110. Patients undergoing elective eye surgery with undiagnosed and untreated HTN should generally be delayed until their BP is evaluated and treated by an internist. Some patients who are anxious will have SBP> 180 and/or diastolic BP> 110 on the day of surgery despite having well-controlled BP preoperatively and are compliant with antihypertensive medication (“white coat syndrome”). For these (adult) patients, it is appropriate to administer a small dose(s) of a benzodiazine (e.g., midazolam 0.5-1 mg IV) or, if no contraindication, a beta blocker (e.g., lopressor 5 mg IV) or smooth muscle dilator (e.g., hydralazine 5-10 mg IV). Sedatives must be give judiciously so that intraoperatively, patients are aware of their surroundings and can respond to verbal commands. Allow sufficient time for the initial dose of sedative and/or antihypertensive agent to have an effect (e.g., 5-10 minutes midazolam and lopressor, 20 minutes hydralazine) before giving an additional dose. One study demonstrated treating diastolic HTN between 110-130 preoperatively on the day of surgery until BP was controlled vs cancelling surgery and making the patient return at a later date when BP was controlled showed no difference in outcomes.

Patients with pacemakers and implanted cardiac defibrillators (ICDs) should be identified far enough in advance of surgery to confirm the device will continue to function appropriately in the perioperative period. Although these devices only occasionally fail unexpectedly, there are recommendations that before any surgical procedure these devices be checked. This check should include identification of the device (e.g., pacemaker? ICD? brand? model?), implanted date, date of last interrogation (our current guidelines; 6 months for pacemakers, 3 months for ICDs), has adequate perioperative battery life, the generator and leads are functioning appropriately, how the generator will respond to a magnet, and in the case of an ICD, if there have been any recent therapies for arrhythmias. (Recent therapy could increase the risk of device discharging during eye surgery, causing the patient to move.) In addition it is prudent to question the patient about any recent episodes of syncope, near syncope, and shortness of breath. (These could be signs of device malfunction or worsening underlying disease.) Patients with ICDs should also be asked about episodes of recent (known) device discharge. If present, and the device is left active intraoperatively, the patient will be at increased risk of the device delivering therapy and possibly causing patient movement.

Adults with undiagnosed murmurs, or moderate or greater severity aortic stenosis, not reevaluated within the previous 12 months should have a preoperative echocardiogram evaluation to rule out significant aortic stenosis, mitral stenosis, a VSD, or an ASD before receiving general anesthesia. Children and adults with complex cardiac abnormalities, even if repaired, should receive a cardiology evaluation before undergoing general anesthesia. If general anesthesia is required in individuals with complex cardiac abnormalities or MAC or general anesthesia is required for patients with single chamber physiology, consideration should be given to performing anesthesia and surgery in a center that has experience with caring for individuals with complex congenital cardiac abnormailities.

Perioperative risk reduction strategies

• Continue most cardiac and HTN medications up to and including the day of surgery. (Hold diuretics on the day of surgery unless required for CHF.)

• It is recommended to continue warfarin and other antithrombotic agents (e.g., clopidogrel [Plavix] and aspirin) for patients prescribed these medications undergoing cataract surgery. For vitrectomies and other eye operations, preoperative consultation between the ophthalmologist and patient’s internist or cardiologist is the best method to asses the perioperative risk of bleeding and develop a perioperative management strategy.

• Patients who had a drug eluting cardiac stent placed within the previous 12 months, or a bare metal cardiac stent within the previous 4-6 weeks, are at high risk of stent clotting if clopidogrel and/or aspirin is stopped within these periods. Elective surgery requiring stopping these medications should be delayed during these periods. If surgery is urgent and the risk of bleeding is considered to be moderate to high, generally clopidogrel is stopped and aspirin is continued perioperatively. A cardiology consultation should be considered if these drugs need to be stopped before the times outlined above.

• Do not administer eye drops that can exacerbate HTN (e.g., NeoSynephrine) until BP is well controlled (e.g., SBP <180, DBP <110). Administer a small additional dose of anti-anxiety and antihypertensive agents only as needed.

• Avoid or treat measures that increase pulse rate and BP (e.g. anxiety, pain, full bladder). If the patient is having eye pain request the surgeon to administer additional local anesthesia.

• For patients with a history of CHF undergoing MAC, minimize time supine. Consider having the head of the bed slightly elevated, or having the bed in reverse trendelenberg position.

• Determine by history, physical exam, and information from the patient’s electrophysiology lab, that pacemakers and ICDs are functioning appropriately preoperatively, and has adequate battery life to function into the perioperative period. Patients with appropriately functioning pacemakers can be operated on with no changes in routine management if a monopolar electrosurgical instrument (e.g. Bovie) is not used. (Rare for ophthalmic procedures)

• ICDs are commonly left active during eye operations if Bovie not used, the ICD has not delivered therapy recently, and the surgeon and anesthesia staff are warned that if an arrythmia is detected, the ICD can delivered electrical therapy with subsequent patient movement within 6-15 seconds. If indicated, most (but not all) ICDs can be temporarily inactivated by placing a magnet over the generator (after have working external defibrillator immediately in room). Preoperatively check with patient’s ICD lab, or manufacturer, how to inactivate and reactivate ICD if this might be necessary.

• Significant valvular lesions should be ruled out preoperatively for patients requiring general anesthesia.

• If general anesthesia is required in individuals with complex cardiac abnormalities, or M.A.C. or general anesthesia is required for patients with single chamber physiology, these patients should be evaluated by a cardiologist preoperatively and consideration should be given to performing anesthesia and surgery in a center that has experience with caring for individuals with complex congenital cardiac abnormailities.

c. Pulmonary

Perioperative evaluation

An acute respiratory condition (e.g., URI), or unstable chonic condition (e.g., asthma or COPD) should be ruled out by history and physical exam. For adults undergoing local anesthesia with MAC, it should be determined if the patient can lie flat for the duration of the procedure without movement or coughing. Be aware that the rare patient with pulmonary artery hypertension, will be at increased isk of morbidity and mortality if GA required. Preoperative consultation wilth a pulmonologist is recommended if GA might be required. Be aware that infants and children born prematurely with bronchopulmonary dysplasia have an increased risk of preoperative respiratory complications that may be compounded by acute pulmonary conditions

Perioperative risk reduction strategies

After discussion with the ophthalmologist, consider delaying surgery for acute or unstable pulmonary conditions until optimized. This might mean delaying surgery a few days to several weeks. For patients with mild asthma, a preoperative bronchodilator or nebulizer treatment may be useful. Exacerbation of severe or chronic pulmonary problems may require management by the patient’s primary care physician or pulmonologist.

d. Renal-GI:

Perioperative evaluation

Patients with a history of kidney disease should have preoperative electrolytes and renal function tests if general anesthesia may be required. These tests should be repeated preoperatively on the day of surgery if the patient receiving dialysis and general anesthesia may be required.

Ensure no unstable GI conditions. Inquire about a history of postoperative nausea or vomiting (PONV).

Perioperative risk reduction strategies

Patients requiring dialysis should be scheduled for surgery whenever possible the day after dialysis. Patients with significant kidney disease should have IV fluids that do not contain potassium. For patients with fluid restrictions the IV infusion rate should be appropriately maintained. If general anesthesia is required, be aware succinyl choline can increase serum potassium 0.5-1.0 mEq/L. Cis-atracurium may be the intermediate muscle relaxant of choice because of its nonrenal elimination and minimal hemodynamic effect.

Confirm that the patient has complied with institution’s NPO guidelines before administering sedation or general anesthesia. Consider administering antiemetic(s) such as odansetron and/or dexamethasone to reduce risk of PONV if general anesthesia is required or patient has a history of PONV with MAC. Consider adding third antiemetic (e.g., scopolamine patch) and/or using TIVA techniques if patient has a significant history of PONV.

e. Neurologic:

Perioperative evaluation

Inquire about history of seizures, CVA, TIA, weakness, chronic pain, tremor, anxiety, claustrophobia, and dementia.

Perioperative risk reduction strategies

Request patient to continue antiseizure, chronic pain, and other essential neurologic medications to time of surgery with sip(s) water. Plan with surgeon preoperatively most appropriate anesthesia technique (e.g., MAC? GA?). If MAC, consider restraining head with tape, maintain verbal contact, reassure patient if necessary, and hold patient’s hand if patient desires. If patient is anxious, consider using clear drape, elevate drape allowing air to circulate onto patient’s face.

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (eg. musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

N/A

4. What are the patient's medications and how should they be managed in the perioperative period?

As a general rule, most essential medications (e.g., most antihypertensives, cardiac, pulmonary, and antiseizure medications) are continued on their normal schedule with a sip(s) water until the time of surgery. (See more detailed recommendations below.) Some herbal medications (e.g., Ginko, ginseng). and many NSAIDs have some antithrombotic properties.

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

For patients taking clopidogrel (Plavix) or other thienopyridines, or aspirin, it is important to ascertain the reason these drugs are being taken. If the patient had a cardiac stent placed within the previous year and these drugs are stopped, it may increase the risk of clotting of the stent. (See recommendations in Cardology section above.) Patients who have taken tamsulosin (Flomax) may have a floppy iris syndrome requiring use of iris hooks to perform cataract surgery and increase the length of surgery slightly.

i. What should be recommended with regard to continuation of medications taken chronically?

Continue most cardiac, antihypertensive, pulmonary, and antiseizure medications on schedule up to and including the day of surgery. Medications may be taken with sips of water. (Hold diuretics on the day of surgery unless required for CHF.) Request the patient to bring inhaler(s) to hospital. See recommendation regarding clopidogrel (Plavix), other thienopyridines, and aspirin above.

Recent guidelines recommend continuing warfarin in therapeutic doses for cataract surgery and other procedures on superficial structures. Some studies suggest the risk of significant bleeding is small if warfarin is continued up to the day of surgery for a vitrectomy. However, there is concern by many retinal surgeons about the possibility of a significant bleeding complication in this situation. For patients who do stop warfarin several days preoperatively, and who are at moderate to high risk of developing a thrombotic complication, recent guidelines suggest considering administration of a low molecular weight heparin for several days preoperatively, with the last dose approximately 24 hours before surgery, and resuming warfarin the evening of or morning following surgery.

Essential renal, neurologic (e.g., antiseizure medications), and psychiatric medications should also be continued up to the time of surgery.

j. How To modify care for patients with known allergies –

Ester anesthetics are avoided for patients with allergies to this class of drug (e.g., procaine [Novocain], tetracaine, chloroprocaine) and amide anesthetics (e.g., lidocaine, bupivacaine) are substituted.

k. Latex allergy- If the patient has a sensitivity to latex (eg. rash from gloves, underwear, etc.) nonlatex containing gloves are used, and drugs with latex caps are removed (not punctured) when drawing up medications. The operating room staff is informed and only with latex free products are used.

N/A

l. Does the patient have any antibiotic allergies- [Tier 2- Common antibiotic allergies and alternative antibiotics]

Allergic reaction to antibiotics are noted and communicated to the surgeon. If the patient has a reaction to a penicillin derivative, and an antibiotic is required, another class of antibiotic is administered (e.g., clindamycin).

m. Does the patient have a history of allergy to anesthesia?

For patients with history of, significant risk factor for, or close family member history of malignant hyperthermia (MH)

• Consider regional anesthesia

• If general anesthesia required

  Ensure MH cart is available

  Avoid succinylcholine and inhalational agents if general anesthesia required

History of sensitivity or allergic reaction to local anesthesia

• Determine if sensitivity likely to be epinephrine, possibly previously mixed with local anesthesia. If so, avoid epinephrine.

  If allergic to local anesthetic (usually ester based), use different class drug (e.g., amide). Also see above.

5. What laboratory tests should be obtained and has everything been reviewed?

Preoperative labwork and ECG are only warranted for specific medical conditions. Guidelines in use (at our institution) for low-risk (eye) surgery include electrolytes for diuretic use, preoperative blood sugar for all diabetics and repeat blood sugar(s) for insulin-dependent diabetics on the day of surgery, INR for patients who took warfarin within 5 days of surgery, BUN/creatinine for renal dysfunction, LFTs, CBC, PT/INR, PTT for severe liver disease, and ECG for patients with history of cardiac disease.

Hemoglobin levels: Only indicated if concerned about severe preoperative anemia (rare)

Electrolytes: Indicated if taking diuretics and/or has kidney disease and GA possible.

Coagulation panel: Indicated for history of bleeding diathesis. Day of surgery INR (fingerstick if possible) for patients who took warfarin 4 days or less before surgery.

Imaging: Not routinely indicated.

Other tests: Not routinely indicated.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

Regional anesthesia of the orbit (usually with sedation during block) and general anesthesia are the two options for providing analgesia and eye akinesia during orbital surgery. Commonly used techniques for orbital regional anesthesia include topical eye drops (mostly used for cataract surgery), extraconal block (sometime referred to as peribulbar block), intraconal block (retrobulbar block), and sub-Tenon’s block.

Regional anesthesia (with or without sedation) and MAC

Regional anesthesia of the orbit (topical or block), usually with sedation for needle blocks, are the most common methods of providing analgesia for adults undergoing procedures on the globe.

Regional anesthesia (with MAC)

Benefits: Low risk of side effects (e.g., prolonged sedation, PONV, sore throat)

Drawbacks: Small risk of injury to eye and surrounding structures, small risk of systemic spread and cardiovascular instability. Increased risk of minor bleeding (e.g. skin hematoma, and conjunctiva bleeding) if taking antithrombotics. Contraindicated if infection at injection site.

Issues: Need cooperative motionless patient. Not appropriate for patients who cannot lie flat for duration of procedure (e.g., has orthopnea, severe claustrophobia, severe sleep apnea,, or dementia)

Slowing of heart rate from block (oculocardiac reflex) common, usually self-limited.

Must be prepared to resuscitate from complications of block. (Self-inflating bag/mask, oxygen, airways, atropine, crash cart must be immediately available.)

Limited access to head and neck during procedure if oversedated.

Fire risk if Fio2 0.50 or greater administered around face (recommend starting Fio2 0.30 or less during surgery)

CO2 can build up under drapes and cause restlessness (can dissipate CO2 by having mouth and nose exposed. If draped, have flows of at least 10 L/min of compressed air or air/oxygen mixture, or use vacuum tubing to remove CO2 buildup)

b. General Anesthesia

Benefits: Patient immobility and anesthesia.

Drawbacks: PONV, longer time until fit for discharge, sore throat, higher risk of postoperative confusion in elderly, higher risk of cardiovascular and respiratory complications.

Other issues: Must ensure patient immobility during procedure (movement can result in damage to eye).

Airway concerns: Must ensure secure airway during intraorbital surgery.

c. Monitored Anesthesia Care (See Regional Anesthesia above)

N/A

6. What is the author's preferred method of anesthesia technique and why?

Regional anesthesia is preferred over general anesthesia because of reduced risk of PONV, reduced time to be street ready postoperatively, no sore throat, reduced risk of cardiovascular and respiratory complications, and reduced medicolegal liability from patient movement if awake.

What antibiotic is given prophylactically?

None routinely. Antibiotic administered only if surgeron requests it.

What do I need to know about the surgical technique to optimize anesthetic care?

Nitrous oxide (N20) can increase intraocular pressure and cause blindness in patients who recently had a medical gas injected into the eye. (A treatment for retinal detachment) To avoid this complication N20 should not be used for patients who have had SF6 injected within the previous 4 weeks, or C3F8 injected within the previous 3 months. Body motion during intraocular surgery can be disastrous. Every effort should be made to prevent movement during introcular surgery. Need to wait until surgeon marks eye before performing orbital block for patients having Toric lens implanted.

What can I do intraoperatively to assist the surgeon and optimize patient care?

Maintain normotension, prevent patient movement.

What is the most common intraoperative complications and how can it be avoided/treated?

Oculocardiac reflex (vagally mediated bradycardia). Avoid by minimizing traction on extraoccular muscles, consider prophylactic orbital block. Treat with anticholinergic (e.g., glycopyrrolate or atropine), orbital block.

a. Neurologic:

N/A

b. If the patient is intubated, are there any special criteria for extubation?

To reduce the risk of straining on the endotracheal tube, many patients are extubated “deep” if they meet commonly used criteria for extubation (e.g., no signficant muscle paralysis by nerve stimulator, respiratory rate 10-18, adequate tidal volume, normothermic, no difficulty with airway or respiratory status anticipated).

c. Postoperative management

What analgesic modalities can I implement?

Frequently acetaminophen is all that is needed for analgesia after minor eye operations (e.g., cataracts). Narcotic are usually required after orbital surgery and sometimes required after other types of ophthalmic surgery. Ketorolac should be considered for procedures likely to cause moderate or severe pain after discussion with surgeon about drug’s mild antithrombotic properties.

What level bed acuity is appropriate?

Most patients are discharged home on the day of surgery. Infants born prematurly (less than 36 weeks) and are less than 60 weeks gestational age are admitted overnight and monitored continuously with oximeter.

What are common postoperative complications, and ways to prevent and treat them?

Serious postoperative complications related to anesthesia are rare after ophthalmic surgery. Patients undergoing general anesthesia can have PONV, sore throat, and somnolence. PONV can be reduced by prophylactic antiemetics (e.g. odansetron and dexamethasone) and a TIVA techniques. Somnolence can be reduced by short actiong anesthethic agents (e.g., propofol, desflurane, remifentanil infusion).

What's the Evidence?

Feldman, MA, Patel, A. “Anesthesia for eye, ear, nose and throat surgery. In Miller's Anesthesia”. 2010. pp. 2378-88. (Good general review on the subject of anesthesia for ophthalmologic surgery.)

Schein, OD, Katz, J, Bass, EB. “The value of routine preoperative medical testing before cataract surgery. Study of medical testing for cataract surgery”. N Engl J Med. vol. 20. 2000. pp. 168-175. (Important paper giving evidence "routine lab & EKG" do not improve perioperative outcomes for cataract surgery.).

“ASA practice advisory for preanesthesia evaluation”. Anesthesiology. vol. 116. 2012. pp. 522-38. (Updated advisory of what preoperative testing is likely to be useful.)

Weksler, N, Klein, M, Szendro, G. “The dilemma of immediate preoperative hypertension; to treat and operate, or postpone surgery”. J Clin Anesth. vol. 15. 2003. pp. 179-83. (Provides evidence that treating hypertension preoperatively on the day of surgery for patients with diastolic BP 110-130 had no worse outcome than canceling surgery, admitting patient and treating patient for hypertension, and performing surgery at a later date for surgery.)

“ACC/AHA 2007 guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery”. JACC. vol. 50. 2007. pp. e159-241. (Excellent general advisory on preoperative cardiac evaluation.)

Douketis, JD, Berger, PB, Dunn, AS. “The perioperative management of antithrombotic therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines”. Chest. vol. 133. 2008. pp. 299S-339S. (Excellent review of the literature. Gives evidence that continuing aspirin and warfarin [in therapeutic levels] perioperatively does not increase the risk of serious perioperative bleeding complications for cataract surgery.)

Rozner, MA. “Implantable cardiac pulse generators: Pacemakers and cardioverter-defibrillators. In Miller's Anesthesia”. 2010. pp. 1389-409. (Excellent review on perioperative management of pacemakers, ICDs, and implanted cardiac devices for CHF.)

Hart, RH, Vote, BJ, Borthwick, JH. “Loss of vision caused by expansion of intraocular perfluoropropane C3F8 gas during nitrous oxide anesthesia”. J Ophthalmol. vol. 134. 2002. pp. 761-3. (Case reports of nitrous oxide causing blindness in patients who had C3F8 gas bubble for retinal detachment.)

Astrom, S, Kjellgren, D, Monestam, E. “Nitrous oxide anesthesia and intravitreal gas tamponade”. Acta Anaesthesiol Scand. vol. 47. 2003. pp. 361-2. (Case report of nitrous oxide causing blindness in patients who had SF6 gas bubble for retinal detachment.)

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