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Anaesthesiology
Anesthesia for Ophthalmologic Surgery
Built from Barash Clinical Anesthesia, 9th Edition
What’s inside
17 sections · 199 slides
Overview
- Scope of ophthalmic anesthesia practice
- What this topic covers
- Core challenges for the anesthesiologist
- Extraocular versus intraocular procedures
- Key points of ophthalmic anesthesia
Anatomy of the Eye
- Openings at the orbital apex
- The sclera and cornea
- The uveal tract
- Innervation of the iris and ciliary muscle
- The retina
- The crystalline lens
- Conjunctiva and eyelids
- Cranial nerve supply to the eye
Physiology of Intraocular Pressure
- Formation of aqueous humor
- Ion transport at the ciliary epithelium
- Pathway of aqueous humor drainage
- What the aqueous bathes on its way out
- Normal intraocular pressure values
- Diurnal variation in intraocular pressure
- Three main factors influencing intraocular pressure
- Vitreous water content and intraocular pressure
- Laryngoscopy, intubation and intraocular pressure
- Equation for aqueous humor formation and intraocular pressure
- Equation for aqueous humor outflow
- Fontana spaces and outflow resistance
Intraocular Pressure Dysregulation: Glaucoma
- Acute versus chronic angle-closure glaucoma
- Closed-angle glaucoma
- Pupillary block from a swollen lens
- Anticholinergics in glaucoma
- Avoiding pressure-raising manoeuvres in glaucoma
- Presentation of infantile glaucoma
Factors Influencing Intraocular Pressure
- Ventilation and temperature effects on intraocular pressure
- Supraglottic airway versus tracheal tube
- Central nervous system depressants and intraocular pressure
- Proposed mechanisms of the fall in intraocular pressure
- Ketamine and intraocular pressure: the controversy
- Hypertonic solutions
- Acetazolamide
- Nondepolarizing neuromuscular blocking drugs
- Succinylcholine and intraocular pressure
- Proposed mechanisms of the succinylcholine pressure rise
- Succinylcholine pressure rise despite nondepolarizing pretreatment
- Evidence on pretreatment with nondepolarizing relaxants
The Oculocardiac Reflex
- Definition and triggers of the oculocardiac reflex
- Reflex arc of the oculocardiac reflex
- Cardiac manifestations of the oculocardiac reflex
- Prophylaxis against the oculocardiac reflex
- Risks of prophylactic intravenous atropine
- Management of an intraoperative oculocardiac reflex
- Cardiopulmonary reaction during ophthalmic artery cannulation
- The trigeminocardiac reflex
Anesthetic Implications of Ophthalmologic Medications
- Routes of systemic absorption of topical eye drops
- Ophthalmic drugs of anesthetic concern
- Echothiophate and prolonged succinylcholine action
- Cocaine in ophthalmic practice
- Cocaine dosing and toxicity
- Treating cocaine-related cardiovascular toxicity
- Phenylephrine eye drops
- Timolol and other nonselective beta-blockers
- Intraocular gas bubbles for retinal detachment
- Nitrous oxide exclusion after intraocular gas
- Consequences of nitrous oxide with a residual bubble
- Contraindications and cautions with acetazolamide
Preoperative Evaluation
- Routine preoperative testing before cataract surgery
- Evidence on continuing antithrombotic therapy
- Regional eye blocks in anticoagulated patients
- Coronary stents and dual antiplatelet therapy
- Dilating drops in poorly controlled hypertension
- Patient movement as a cause of eye injury
- Congenital and metabolic diseases with ocular manifestations
Anesthesia Options and Site Verification
- Requirements the anesthetic must meet
- The range of anesthetic options
- Who gets general anesthesia and who gets a block
- Procedures beyond cataract surgery
- The universal protocol for correct site surgery
Anesthesia Techniques
- Evolution of general anesthesia for eye surgery
- The orbital muscle cone
- Technique of the intraconal (retrobulbar) block
- Uses of intraconal and extraconal blocks
- Technique of the extraconal (peribulbar) block
- Limits of the classification by needle position
- Comparison of intraconal and extraconal blocks
- Needle entry point for both blocks
- Needle length in ophthalmic blocks
- Direction of gaze during the block
- Facial nerve block for eyelid akinesia
- Hazards of the Nadbath-Rehman block
- Retrobulbar hemorrhage
- Risk factors for posterior pole needle injury
- Why intraconal injection carries more penetration risk
- Preanesthesia screening for the high-risk globe
- Ultrasound-guided eye blocks
- Mechanism of brainstem anesthesia
- Other neurological signs of central spread
- Technique of the sub-Tenon block
- Advantages of the sub-Tenon block
- Major complications of sub-Tenon anesthesia
- Poor candidates for topical analgesia
- Drops versus gels for topical analgesia
- Intraoperative floppy iris syndrome
- Bupivacaine and ropivacaine in eye blocks
- Hyaluronidase in ophthalmic blocks
- Hazards and safeguards of compression devices
Monitored Anesthesia Care
- Dangers of deep sedation in eye surgery
- The target state after a block
- Positioning and comfort on the operating table
Anesthetic Management in Specific Situations
- The open-eye, full-stomach dilemma
- Evidence for blocks in selected open-globe injuries
- Induction options depending on urgency
- Controlling the induction in a true emergency
- The 1957 Lincoff report re-examined
- The anticipated difficult airway with an open globe
- Intraocular pressure control before scleral incision
- Achieving maximal pupillary dilation intraoperatively
- Scleral buckling for retinal detachment
- Nitrous oxide and the intraocular gas bubble
- Timing rules for nitrous oxide around gas injection
- Patients at higher risk from bubble expansion
- Sudden death during retina surgery
- Proposed mechanism of venous air embolism in vitrectomy
- Scale of the air flows involved
- Preventing and detecting air embolism in retina surgery
- Fovea-sparing versus fovea-involving detachment
- Definition and surgery for strabismus
- Anesthetic concerns unique to strabismus surgery
- The forced duction test
- Practical rules on succinylcholine in strabismus surgery
- Airway management for strabismus surgery
- The oculogastric reflex
- Droperidol for postoperative vomiting
Principles of Laser Therapy
- Physical properties of laser radiation
- Eye protection for operating room personnel
- The Nd:YAG laser
- The excimer laser
- Treatment of age-related macular degeneration
Postoperative Ocular Complications
- Incidence of eye injury after nonocular surgery
- Two categories of postoperative eye problem
- Incidence of corneal abrasion under general anesthesia
- Mechanisms of corneal abrasion
- Protecting the eyes during anesthesia
- Disadvantages of ophthalmic ointments
- Diagnosis of corneal abrasion
- Goggle colour by laser type
- Postsurgical acute angle-closure glaucoma
- Managing patients at risk of acute angle-closure glaucoma
- Distinguishing corneal abrasion from acute glaucoma
- Valsalva retinopathy
- Positioning and external pressure on the eye
- Practical positioning rules for the prone patient
- Causes of central retinal artery occlusion
- Treatment and prognosis of central retinal artery occlusion
- Risk factors for ischemic optic neuropathy after prone spine surgery
- Risk factors for anterior ischemic optic neuropathy
- Fluid, edema and optic nerve perfusion
- Preventive strategies for anterior ischemic optic neuropathy
- Treatment and prognosis of anterior ischemic optic neuropathy
- Epidemiology of posterior ischemic optic neuropathy
- Mechanism and presentation of posterior ischemic optic neuropathy
- Distinguishing posterior from anterior ischemic optic neuropathy
- ASA practice advisory on perioperative visual loss
- Cortical blindness
- Postcataract ptosis
Summary and Takeaways
- Take-home points on intraocular pressure
- Take-home points on regional eye blocks
- Take-home points on reflexes and gases
- Take-home points on postoperative complications
Reference Tables
- Requirements of Ophthalmic Surgery
- Differential Solubilities of Gases
- Complications of Needle-based Ophthalmic Anesthesia
- Complications of Needle-based Ophthalmic Anesthesia (continued)
- Concerns with Various Ocular Procedures
References
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- Barash, Cullen, and Stoelting's Clinical Anesthesia, 9th Edition