What the Anesthesiologist Should Know before the Operative Procedure
Anesthesia management plays a pivotal role in vitreoretinal surgery. Unexpected patient movement during delicate microscopic intraocular surgery can lead to increased intraocular pressure (IOP), choroidal hemorrhage, extrusion of intraocular contents, and loss of vision. Therefore, the avoidance of movement, coughing, and straining is essential during vitreoretinal procedures.
Patients with increased IOP or penetrating eye injuries are liable to sustain further damage from sudden changes in IOP.
1. What is the urgency of the surgery? What is the risk of delay in order to obtain additional preoperative information?
There is a low mortality associated with surgery on the retina. Delay in treatment may result in the loss of vision. Most vitreoretinal procedures can be done under local anesthesia following a retrobulbar or peribulbar block. Contraindications for the use of local anesthesia include chronic cough, claustrophobia, involuntary tremor, excessive anxiety, confusion, the inability to lie flat for long periods of time, a language barrier, a ruptured globe, and infection at or near the injection site.
Emergent: Emergency vitreoretinal procedures should be performed for patients with acute endophthalmitis and open globe injuries with intraocular foreign body to control infection and prevent loss of vision.
Urgent: Urgent vitreoretinal procedures should be performed as soon as appropriate for patients with acute retinal detachment that threatens the fovea; delay in treatment may result in loss of vision.
Elective: Elective vitreoretinal procedures can be performed for patients with macula-off retinal detachment. In these cases, the repair should be performed at the earliest convenience, preferably within a few days. Chronic retinal detachment is an ongoing problem in that the retina has been detached for a few weeks, and surgery can be scheduled within 1 week of diagnosis.
The anesthesia issues for each of these surgeries are similar as the patient must lie still so that the ophthalmologist can work on the retinal problems. The duration of surgeries may differ, but essentially, the anesthesia must provide a very still patient who can tolerate surgery involving one or both eyes.
2. Preoperative evaluation
Patients presenting for vitreoretinal surgery tend to be very young or very old. Elderly patients are likely to have illnesses affecting multiple organ systems, such as hypertension, diabetes, coronary artery disease, chronic lung disease, or parkinsonism. Small children with retinal disease may also have general immaturity, apnea, bradycardia, or bronchopulmonary dysplasia (BPD). Preoperative consultations should be obtained well in advance of the scheduled date of surgery.
Patients with retinal disease frequently have a history of diabetes with concomitant cardiovascular and renal disease. Fasting blood sugar should be established before surgery, IV infusion with D5 lactated Ringer’s should be started, and half of the patient’s usual insulin dose should be given. A preoperative ECG is indicated for patients with diabetes or signs and symptoms of cardiac disease.
Potassium, BUN, and creatinine tests are indicated for patients who take diuretics and/or have renal disease. Coagulation studies may be indicated for patients with history of coagulopathy or anticoagulation as a medical treatment. Warfarin and antiplatelet drugs (e.g., aspirin and clopidogrel) may be held for 5 days before surgery. However, the small risk of a bleeding complication should be balanced against the risk of restenosis and thrombosis if these medications are discontinued.
Overall, given that the patient’s sight may be at risk, preoperative risks need to be extraordinary to preclude surgery. Acute angina, stroke, or new myocardial infarct would delay surgery. However, eye surgery involves extremely small amounts of blood loss, minimal fluid shifts, and minimal perturbation to vital signs and, therefore, only these extreme problems usually delay emergency surgery.
Medically unstable conditions warranting further evaluation include patients with uncontrolled hypertension, uncontrolled diabetes, myocardial infarction, active ischemia, unstable arrhythmia, stroke, COPD exacerbation, or respiratory distress.
Patients with cardiac ischemia causing restricted activity, breathlessness, an inability to lie flat, congested neck veins, or ankle edema implies decompensation and high risk. Such patients should be treated and stabilized before surgery.
Angina at rest or angina with increasing frequency should be referred to a cardiologist for work up and stabilization.
Hypertension is very common in elderly patients. Patients with a preoperative diastolic pressure greater than 110 mm Hg and systolic pressure greater that 180 mm Hg should be treated until the hypertension is better controlled.
Atrial fibrillation, right bundle branch block (RBBB), and first-degree AV block are common in elderly patients; they have no significance if the heart rate is within normal limits and vital signs are stable. Variable blocks causing severe bradycardia should be referred to a cardiologist for pacemaker or other treatment.
Patients with stable COPD and those with well-controlled asthma are at minimal risk for complications. For the patients with bronchospasm, cough, sputum, or supplemental oxygen dependence should be evaluated and treated so that the patient is in the best possible condition for surgery. Under local anesthesia, the patient may be unable to lie flat and sudden cough may endanger the eye. General anesthesia may lead to bronchospasm, pneumonia, and postoperative respiratory failure. Placing the patient supine can help determine whether the patient can tolerate the procedure under local anesthesia with sedation. If the patient coughs or has trouble breathing, general anesthesia is indicated. Bronchospasm can be treated with inhaled bronchodilators, inhaled anesthetics, and local anesthesia. Narcotics can help suppress coughing.
Delaying surgery may be indicated if the unstable medical conditions mentioned above are not able to be controlled.
3. What are the implications of co-existing disease on perioperative care?
Most vitreoretinal procedures can be performed under regional anesthesia. The procedures have little systemic impact and are associated with a very low rate of general morbidity or mortality, despite the high-risk population. However, when considering the potential complications from regional and general anesthesia, all patients should have a preoperative history and physical examination to assess their medical conditions and ensure they are optimized for surgery.
a. Cardiovascular system
Most vitreoretinal procedures are not urgent and are elective in nature. Angina at rest or angina with increasing severity or frequency should be treated prior to ophthalmic surgery. A preoperative work-up may include a 12-lead ECG, cardiac biomarker evaluation, and cardiologist consultation. Arrhythmias may require rate control or a temporary pacemaker.
Many elderly patients have Q waves or inverted T waves on their ECG, indicating previous myocardial damage and suggesting that more myocardial damage could occur at any time. Restricted activity, shortness of breath, an inability to lie flat, congested neck veins, and edema imply decompensation and high risk. Such patients should be treated and stabilized before surgery.
Atrial fibrillation, RBBB, and first-degree AV block are common in elderly patients. These conditions have no significance if the heart rate is within normal limits. In these patients, the goal of management is to avoid gross tachycardia or bradycardia. Bradycardia or tachycardia with unstable vital signs should be treated and referred to a cardiologist for other treatment.
Irregular beats that are infrequent are of no significance in ophthalmic surgery. When they occur with every beat (bigeminy), a cardiologist consultation is needed. For patients without changes in medical history, normal labs and ECGs do not need to be repeated if they were completed within the past 6 months.
Hypertension is also common in the elderly population. Ideally, control and stabilize blood pressure to a systolic pressure below 180 mm Hg and a diastolic pressure below 110 mm Hg. It is important to continue antihypertensive medications up to the time of surgery.
To reduce perioperative risk, continue current cardiovascular medications. Consider beta blockers to reduce the heart rate. Also, optimize the myocardial oxygen supply-and-demand ratio. Maintain normal blood pressure and oxygenation throughout the procedure.
The perioperative evaluation of COPD and reactive airways disease (asthma) includes a careful clinical history, including pack-year history of smoking, assessment of the severity of disease, and frequency of exacerbations, emergency department visits, hospitalization, ICU admission and intubation, recent steroid therapy, oxygen requirements, and medication regimen.
Bronchospasm, cough, sputum, and poor gaseous exchange present problems for the procedure, whether the procedure is to be done under local or general anesthesia. Under local anesthesia, the patient may not be able to lie flat and paroxysms of cough may endanger the eye. General anesthesia may lead to postoperative respiratory failure, sputum retention, and pneumonia. Patients with stable COPD and no uncontrolled cough who are able to lie supine for the duration of the procedure are probably at low risk for complications.
Perioperative risk reduction strategies
These strategies for COPD include continuing current pulmonary medications. Consider smoking cessation and starting nebulizer treatments and steroid therapy, if needed. If general anesthesia is chosen, ensure that the patient is deeply induced and muscles are fully relaxed prior to intubation, to avoid bronchospasm. Consider pulmonary toilet, nebulizer treatment, and steroid therapy postoperatively.
Patients with advanced age and a history of diabetes may present with diminished renal function and delayed renal drug clearance. Some patients may have chronic renal insufficiency.
The preoperative evaluation should include a history that includes questions about polyuria, dysuria, fatigue, edema, diuretics, potassium supplementation, and carbonic anhydrase inhibitors. In dialyzed patients, determine when the dialysis will be done preoperatively. Lab tests, including baseline creatinine, BUN, sodium, and potassium, should be checked.
Because of the potential dangers of hyperkalemia for cardiac problems, plasma potassium concentration should be within normal limits for elective surgery. Acid-base balance can be ascertained by evaluating serum electrolytes. If renal failure patients need emergent operations, hyperkalemia and acidemia may need to be treated with insulin and glucose and increased ventilation, respectively.
Perioperative risk reduction strategies
These include avoiding potential drugs that are toxic to the kidneys and rehydrating dehydrated patients prior to induction of anesthesia.
Elderly patients have decreased upper airway reflexes and an increased incidence of gastric reflexes/regurgitation, making them susceptible to aspiration. Diabetic patients may have gastroparesis.
Perioperative risk reduction strategies
These strategies for gastrointestinal complications include the prophylactic use of gastric volume-reducing strategies, rapid sequence intubation [if indicated], and antacid medications
The effects of succinycholine on IOP are controversial, but there is evidence that succinylcholine may cause further eye injury. A rapid sequence induction may be needed for a patient with a full stomach and open globe injury; nondepolarizing neuromuscular blocking agents might be utilized for this.
Patients with unstable conditions, such as transient ischemic attacks and stroke, should be stabilized prior to surgery.
Patients with chronic neurologic diseases, such as Parkinson’s disease with uncontrolled tremor, may require general anesthesia.
Patients with retinal disease frequently have a history of diabetes. The blood sugar should be tested soon after admission to hospital. For the insulin-dependent diabetic patient, a maintenance intravenous infusion with D5 lactated Ringer’s should be started and half of the patient’s usual insulin dose administered. Blood sugar must be checked intraoperatively and postoperatively. For non–insulin-dependent diabetic patients, routine oral medications should be held the morning of surgery. Frequent testing of the blood sugar and use of intravenous glucose may be required.
f. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (e.g., musculoskeletal in orthopedic procedures, hematologic in a cancer patient)
It is important to recognize the danger of using nitrous oxide (N2O) in patients who have gas in the eye. The most commonly used medical gases for vitreoretinal surgery are sulfur hexafluoride (SF6) and octafluoropropane (C3F8). Avoid N2O if these intraocular gases are used. These gases are very insoluble and persist for 3-4 weeks. N2O enters the intraocular gas bubble much more rapidly than SF6 and C3F8 exit. The bubble may increase in size by 250% in 30 min. N2O should be avoided in patients who have had SF6 injected to the eye within the last 3 weeks or C3F8 within last 3 months.
g. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?
Most ophthalmic medications are highly concentrated and can have rapid systemic effects when absorbed.
For example, timolol is a beta blocker that can cause bradycardia and bronchospasm. Phenylephrine eye drops can cause hypertension and myocardial ischemia. One drop of 10% phenylephrine may contain 5 mg of phenylephrine. Epinephrine (a 2% solution contains 0.8 mg per drop) can cause tachycardia and premature ventricular contractions (PVCs).
Echothiophate iodide is a long-acting anticholinesterase agent that depresses plasma cholinesterase activity for 2-4 weeks. Patients on this medication will have a prolonged response to succinylcholine. Careful titration of succinylcholine with muscle twitch response (train of four) will avoid prolonged paralysis. Acetazolamide is a carbonic anhydase inhibitor and interferes with the formation of aqueous humor and lowers IOP. Patients taking acetazolamide chronically may become hyponatremic or hypokalemic or develop metabolic acidosis.
Many patients presenting for vitreoretinal surgery are on antiplatelet or anticoagulant therapy. Such patients are at higher risk for bleeding, including retrobulbar hemorrhage, conjunctival and eyelid bleeding, and hyphema. Stopping these medications may increase the risk of myocardial ischemia, cerebrovascular accident, and deep venous thrombosis. The risks of thrombosis and restenosis should be balanced against the increased bleeding from surgical site.
h. What should be recommended with regard to continuation of medications taken chronically?
Chronic cardiac medications, including beta blockers, should be continued. See above comments for aspirin, clopidogrel, and warfarin. For antiplatelet and anticoagulant medications, the risks of restenosis and thrombosis need to be balanced against the increased bleeding from the surgical site.
Chronic pulmonary medications should be continued, as well as chronic renal and neurologic control medications. Chronic antidepressant and antianxiety medications should also be continued.
i. How to modify care for patients with known allergies –
Allergic reactions to local anesthesia are very rare and questioning the patient for histories of allergy needs to be done routinely. If a patient shows signs of an allergic reaction, the treatment is supportive. Bronchoconstriction is treated by administration of bronchodilators and epinephrine (0.3 mg SQ) if the bronchospasm is severe. The dose can be repeated every 15 minutes as needed. Hypotension should be managed by the administration of fluids and vasopressors, including epinephrine, if the hypotension is severe. Cutaneous reactions, particularly itching, may respond to the administration of histamine blockers.
j. Latex Allergy –
If the patient has a sensitivity to latex (e.g., rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.
k. Does the patient have any antibiotic allergies?
For patients with penicillin allergy, use clindamycin or vancomycin.
The rate of postoperative eye infections in cataract surgery is 0.06%. For cataract surgeries, topical povidone-iodine and gentamic irrigation are all that is needed to prevent infection. For retinal surgeries, the rate appears to be 0.04%. Therefore, the rates of postoperative eye infections are very low and there is a lack of consensus on optimal antibiotic prophylaxis for the various eye procedures.
l. Does the patient have a history of allergy to anesthesia?
Patients may have allergic reactions to induction agents (propofol, barbiturates, etomidate), muscle relaxants, and opioids. It is important to avoid antigen exposure and be ready to treat cardiopulmonary collapse.
As with all perioperative patients, a history of malignant hyperthermia (MH) requires the avoidance of all trigger agents(succinylcholine and inhalational anesthetics) and the use of medications that have not been associated with this condition (i.e.,fixed agents such as propofol and narcotics). Clean ventilators should be used in these cases.
Local anesthetics are safe in MH patients. Avoid succinylcholine and use only nondepolarizing muscle relaxants.
5. What laboratory tests should be obtained and has everything been reviewed?
In addition to a thorough history and physical examination, appropriate laboratory tests should be ordered based on patient’s condition.
Complete blood count and electrolyte tests are recommended in older patients.
For specific conditions, such as diabetes and renal failure, laboratory tests are indicated if they have not been done within a few weeks of the proposed surgery. Coagulation studies can be done if the patient has a history of bleeding or clotting disorders or is on medication that disrupts coagulation. A hematocrit and white cell count need to be done only if the patient has a history suggesting that this test would be abnormal, such as in hematologic malignancy or a bleeding disorder.
In patients with systemic disease or medications that affect the kidneys, a blood urea nitrogen (BUN) and creatinine tests are indicated. Electrolytes should be considered in patients with abnormal renal function or on diuretics.
Potassium levels should be obtained for patients using a diuretic and hemodialysis patients.
A coagulation panel is required for patients on warfarin or chemotherapeutic agents or with a history of bleeding disorder or with liver disease, malnutrition, and/or malabsorption.
Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?
The procedure can be performed under regional anesthesia (retrobulbar and peribulbar block) and general anesthesia.
The goals of general anesthesia for eye surgery include smooth induction with stable pressures in the eye, full proper depth of anesthesia to prevent eye motion, coughing, bucking, smooth emergence and extubation, and avoidance of postoperative nausea and vomiting (PONV).
Most vitreoretinal surgery can be done under local anesthesia, provided patients are able to lie flat without movement for the duration of surgery, have no uncontrollable cough or movement, have no language barrier, and are able to communicate with the surgeon and anesthesia staff. The oculocardiac reflex (OCR) is very rare under regional anesthesia.
A retrobulbar block (RBB) can be achieved by injecting a small volume of local anesthesia (3-5 mL) inside the muscular cone. This type of anesthesia has a faster onset and higher success rate than peribulbar block (PBB).
The potential risks of an RBB include perforation of the globe, injury to the rectus muscles, needle penetration of optic nerve sheath, intravenous injection, intra-arterial injection, retrobulbar hematoma, and OCR elicited by injection. Remember that injections of local anesthesia intravascularly [venous or arterial] may lead to complications including cardiac rhythm disturbances and even cardiac arrest.
A PBB requires introducing the needle into the extraconal space and may reduce the risk of injury to major structures in the intraconal space but at the cost of a slightly lower success rate.
The drawbacks of PBB include the large volume of local anesthesia (7-12 mL) that is required and the slower onset than with RBB. Additionally, PBB can cause serious complications, similar to those from RBB, if it is performed incorrectly.
The benefits of general anesthesia include a secure airway, complete control of the patient, and no risk of globe perforation or retrobulbar hemorrhage. General anesthesia is appropriate for combative or delirious patients, as well as pediatric patients.
The drawbacks of general anesthesia include changes in hemodynamics and a prolonged recovery. Patients are also prone to PONV.
Monitored Anesthesia Care
Monitored anesthesia care is not appropriate for vitreoretinal procedures.
6. What is the author's preferred method of anesthesia technique and why?
The choice of technique reflects a balanced judgment of patient safety, cooperation of the patient, surgical difficulty, and the length of the procedure.
Regional anesthesia has benefits of fewer episodes of hemodynamic fluctuation, freedom from hormonal stress response associated with general anesthesia, less postoperative pain, potential reduction in perioperative rate of DVT and PONV, patient with pulmonary disease may benefit from maintaining their own breathing, full mental status is retained, fast recovery, and no risk of MH. With these caveats in mind, it seems prudent to avoid general anesthesia if possible.
What prophylactic antibiotics should be administered?
Antibiotics are not routinely required for ophthalmic surgery.
What do I need to know about the surgical technique to optimize my anesthetic care?
If the surgery is performed under local anesthesia, a calm, motionless, and cooperative patient is the key for the procedure. If the procedure is performed under general anesthesia, a smooth induction with a stable IOP, avoidance or treatment of OCR, and a smooth emergence are essential.
What can I do intraoperatively to assist the surgeon and optimize patient care?
The goal is to maintain a motionless field intraoperatively. This can be accomplished by using inhalational anesthesia, muscle relaxants, and remifentanil or propofol infusions.
What are the most common intraoperative complications and how can they be avoided/treated?
Unexpected patient movement during the delicate microscopic retinal repair may result in loss of vision. Therefore, deep inhalational anesthesia, supplemented with intermediate-acting muscle relaxant or remifentanil infusions, is recommended during the intraocular procedures. The OCR may be initiated by surgical traction on the extrinsic eye muscle or direct eye pressure, and this reflex may cause bradycardia and asystole. The OCR can be treated by cessation of the surgical stimulus, IV atropine, or regional anesthesia [orbital block].
Another potential complication is venous air embolism (VAE) during air tamponade of the vitreous cavity with simultaneously opened choroidal vessels. Anesthesiologists should be aware that ocular air fluid exchange is not completely safe and may even be fatal especially for patients with patent foramen ovale (PFO). Paradoxical air embolism can cause obstruction of coronary and cerebral arteries. The goals of management of VAE are to support the cardiovascular system, stop the influx of air at surgical site which include notifying surgeon, discontinuing procedure, use of 100% of oxygen, aspiration of air from central venous catheter, use of vasopressors and intravascular volume infusion.
a. If the patient is intubated, are there any special criteria for extubation?
Deep extubation should be performed, if possible, to prevent coughing on the endotracheal tube.
b. Postoperative management
What analgesic modalities can I implement?
Postoperatively, oral pain medications may be provided, as well as intravenous pain medications.
What level bed acuity is appropriate?
Stage 1 or stage 2 recovery is appropriate following this procedure, depending on the patient’s condition. Most patients can be discharged home in a few hours.
What are common postoperative complications, and ways to prevent and treat them?
Postoperative complications such as delirium and postoperative DVT and pulmonary embolism are very, very rare if the procedure is performed under local anesthesia.
What's the Evidence?
Stoelting, R, Dierdorf, SF. “Anesthesia and co-existing disease”. 2008. (A general text with comprehensive discussions of diseases that often require eye surgery.)
Firestone, L, Lebowitz, PW, Cook, CE. “Clinical anesthesia procedures of the Massachusetts General Hospital”. 1988. pp. 346-364. (Short descriptions of anesthesia for eye surgery.)
McGoldrick, K. “Anesthesia for ophthalmic and otolaryngologic surgery”. 1992. pp. 259(An expert in out-patient surgeries describes anesthesia for eye surgeries.)
Barash, P. “Clinical anesthesia”. 2009. pp. 1321(General text on anesthesia for eye surgeries.)
Ledowski, T, Kiese, F, Jeglin, S, Scholz, J. “Possible air embolism during eye surgery”. Aneth Analg. vol. 100. 2005. pp. 1651-1652. (A case report of air embolism during vitrectomy.)
Morris, RE, Sapp, MR, Oltmanns, MH, Kuhn, F. “Presumed air by vitrectomy embolisation (PAVE) a potentially fatal syndrome”. Br J Ophthalmo. vol. 98. 2014 June. pp. 765-8. (Experiments to investigate the possibility of air embolism during vitrectomy.)
Nouvellon, E, Cuvillion, P, Ripart, J. “Regional anesthesia and eye surgery”. Anesthesiology. vol. 113. 2010. pp. 1236(A good description of regional procedures done for eye surgeries.)
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- What the Anesthesiologist Should Know before the Operative Procedure
- 1. What is the urgency of the surgery? What is the risk of delay in order to obtain additional preoperative information?
- 2. Preoperative evaluation
- 3. What are the implications of co-existing disease on perioperative care?
- a. Cardiovascular system
- b. Pulmonary
- c. Renal-GI
- d. Neurologic
- e. Endocrine
- f. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (e.g., musculoskeletal in orthopedic procedures, hematologic in a cancer patient)
- h. What should be recommended with regard to continuation of medications taken chronically?
- i. How to modify care for patients with known allergies -
- j. Latex Allergy -
- k. Does the patient have any antibiotic allergies?
- l. Does the patient have a history of allergy to anesthesia?
- 5. What laboratory tests should be obtained and has everything been reviewed?
- 6. What is the author's preferred method of anesthesia technique and why?
- What prophylactic antibiotics should be administered?
- What do I need to know about the surgical technique to optimize my anesthetic care?
- What can I do intraoperatively to assist the surgeon and optimize patient care?
- What are the most common intraoperative complications and how can they be avoided/treated?
- a. If the patient is intubated, are there any special criteria for extubation?
- b. Postoperative management