Anesthesia for Ophthalmic Surgery Flashcards

Question

Impairment of aqueous drainage at any point can elevate the IOP. ... is believed to cause the chronic pressure elevation in open-angle glaucoma. Closed-angle glaucoma occurs when ... . This happens from peripheral iris swelling or anterior displacement. Patients with a preexisting ... may be predisposed to this condition

Answer 1

Sclerosis of the trabecular meshwork there is an obstruction to aqueous drainage from closure of the anterior chamber angle narrow angle

Answer 2

All volatile anesthetic drugs cause a decrease in IOP. Nitrous oxide (N2O) has no effect on IOP.

Answer 3

The commonly used intravenous induction anesthetics such as propofol, thiopental, and etomidate all reduce IOP, with propofol causing a moderate reduction in IOP even when used as low-dose intravenous sedation. Ketamine does not increase IOP Midazolam has little effect on IOP, and sedation with midazolam has been used to facilitate the measurement of IOP in children.

Answer 4

depression of central nervous system ocular centers, resulting in relaxation of extraocular muscle tone

Answer 5

Short-acting opioids such as fentanyl, alfentanil, and remifentanil decrease IOP on induction of anesthesia

Answer 6

Nondepolarizing neuromuscular blocking agents (NMBAs) such as rocuronium, vecuronium, and atracurium have little effect on IOP

Answer 7

Succinylcholine increases IOP by about 8 to 10 mm Hg due to a variety of postulated mechanisms including reduced aqueous humor outflow, increased choroidal blood volume, and increased central venous pressure

Answer 8

laryngoscopy and emergence laryngoscopy

Answer 9

F Video-guided laryngoscopy causes a smaller increase in IOP than direct laryngoscopy. Insertion of a laryngeal mask airway results in little or no increase in IOP.

Answer 10

compression of the eyes during ventilation, hypoxia, hypercapnia, and hypertension 30 to 40mm Hg.

Answer 11

F Ocular blocks initially increase IOP by 5 to 10mm Hg, but this falls to below baseline values within 5 minutes.

Answer 12

Peribulbar blocks

Answer 13

Confusion, drowsiness, hypokalemia, hyponatremia, metabolic acidosis, abnormal hepatic function tests, polyuria, renal failure

Answer 14

Anticholinergic Mydriasis, cycloplegia

Answer 15

Phacoemulsification

Answer 16

Femtosecond laser

Answer 17

Extracapsular cataract extraction

Answer 18

Intracapsular cataract extraction

Answer 19

Trabeculectomy Mitomycin C or 5-flurouracil (5-FU)

Answer 20

Baerveldt and Ahmed

Answer 21

CyPass, iStents, and trabectome.

Answer 22

Penetrating keratoplasty

Answer 23

Scleral buckle

Answer 24

Radioactive plaque implantation

Answer 25

ectropion entropion ptosis blepharoplasty

Answer 26

Dacryocystorhinostomy

Answer 27

Evisceration refers to the removal of the contents of the eye. Enucleation refers to removal of the eye itself including the globe, but leaving orbital contents such as bone, extraocular muscles, and fat in place. Exenteration refers to the removal of the entire contents of the orbit including the lacrimal gland, optic nerve, and orbital bones.

Answer 28

- Myocardial infarction, within 30 days for uncomplicated infarction and within 60 days for complicated infarction - Percutaneous coronary interventions, within 14 days without stents or 30 days with stents - Significant arrhythmias with hemodynamic compromise, e.g., ventricular tachycardia, atrial fibrillation with rapid ventricular rates - Decompensated heart failure - Acute serious pulmonary conditions, e.g., active pneumonia, upper respiratory infection with active symptoms, pulmonary embolus in past 3 months - Acute or recent severe neurologic conditions (e.g., altered mental status, stroke or transient ischemic attacks [TIA] within 3 months, uncontrolled epilepsy, increased intracranial pressure) - Malignant hypertension - Diabetic ketoacidosis or hyperosmolar hyperglycemic nonketotic syndrome

Answer 29

orbital and oculoplastic surgery vitreoretinal, glaucoma, and corneal transplant cataract surgery

Answer 30

intraretinal hemorrhage, choroidal hemorrhage, vitreous hemorrhage, hyphema, and retrobulbar hemorrhage 0.4

Answer 31

F It is safe to proceed with cataract surgery without stopping antiplatelet or warfarin therapy provided that the international normalized ratio level is within the therapeutic range

Answer 32

For intermediaterisk surgery such as glaucoma surgery, warfarin and antiplatelet drugs may increase the risk of ntraoperative or postoperative bleeding. Survey studies show that 30%–80% of glaucoma surgeons discontinue anticoagulants 4–7 days prior to surgery and restart it the day after surgery, but other surgeons do not stop anticoagulants at all. If an interruption of anticoagulation treatment is needed, an individualized approach is recommended to minimize the risk of perioperative bleedin

Answer 33

Ocular blocks are rarely associated with severe hemorrhagic complications

Answer 34

Retrobulbar peribulbar sub-Tenon

Answer 35

Retrobulbar block is achieved by injecting local anesthetic inside the muscular cone. With the globe in primary gaze, a 3-cm, 23- to 27-gauge needle with its bevel opening faced toward the globe is placed at the junction of the inferior and lateral walls of the orbit just above the inferior orbital rim. The needle is advanced parallel to the orbit floor (with a 10-degree elevation from the transverse plane) for approximately 15mm until it is past the equator of the eye. The needle is turned medially and slightly upward to aim toward an imaginary point behind the globe on the axis formed by the pupil and the macula where 2 to 5mL of local anesthetic solution is injected. The needle tip approaches but does not pass the midsagittal plane of the globe

Answer 36

the superior oblique muscle is outside the muscle cone and may not be blocked.

Answer 37

F Many modifications to the classical retrobulbar anesthetic injection have been described to minimize complications of the block. Traditionally, blunt-tipped needles were advocated because they were thought to protect against ocular trauma and because they allowed more accurate definition of tissue planes. However, studies have shown that blunt needles are as likely as sharp needles to cause globe penetration and optic nerve injury. Fine cutting needles produce minimal tissue distortion with little pain.

Answer 38

quicker less

Answer 39

1) Retrobulbar hemorrhage complicates about 1% of retrobulbar injections: - Venous hemorrhage spreads slowly and does not usually result in long-term visual problems; - Arterial hemorrhage can produce rapid orbital swelling, marked proptosis with immobility of the globe, inability to close the lids, and massive blood staining of the lids and conjunctiva. Compressive hematoma can threaten retinal perfusion, leading to severe visual loss. 2) Intravascular injection can occur despite a negative aspiration test. - The total dose of local anesthetic used is small, and systemic effects are unlikely, even if the total dose is given intravenously. - Accidental intra-arterial injection can cause central nervous system excitation and seizures. This occurs because of retrograde passage of local anesthetic solution from the ophthalmic artery to the internal carotid artery and delivery to the thalamus and other midbrain structures. 3) Injection of local anesthetic or retrograde tracking of local anesthetic along the optic nerve sheath into the subdural or subarachnoid space causes partial or total progressive brainstem anesthesia. Wideranging symptoms occur, from aphasia, confusion, and dysphagia to apnea, cardiac arrest, loss of consciousness, and seizures. 4) Optic nerve damage 5) Globe perforation with retinal detachment and vitreous hemorrhage

Answer 40

physician inexperience and a highly myopic eye (axial length longer than 25mm).

Answer 41

For this block, the needle is introduced outside the cone, thus preventing retrobulbar hemorrhage and reducing the risk of optic nerve injury. The classic technique involves two injections: one inferiorly and temporally and the second superiorly and nasally. Peribulbar anesthesia may also be administered with one injection; a 3-cm, 23-gauge Atkinson needle is placed at the junction of the middle and lateral thirds of the lower lid just above the inferior orbital rim. The needle should be directed vertically backwards, parallel to the floor of the orbit. The needle insertion depth should be less than 25 mm. If contact is made with bone, the needle should be redirected slightly upward; then 5 to 10 mL of local anesthetic is injected. Studies support the use of peribulbar block in providing equivalent patient analgesia and operating conditions as retrobulbar block for a variety of ophthalmic procedures

Answer 42

To avoid the complications associated with the use of sharp needles, a technique was developed using a blunt cannula under the fascia of Tenon. Various lengths of cannulas have been used. Using topical anesthesia with sedation, a speculum is placed to retract the lids. A 2- to 3-mm spot of cautery can be made 5mm from the limbus in the inferonasal or inferolateral quadrant. A 2-mm incision is made in the conjunctiva with blunt dissection through the fascia. A blunt cannula is directed posteriorly, but not beyond the equator of the globe, with injection of 1 to 3mL of local anesthetic. A small degree of conjunctival edema is often seen. Analgesia is usually excellent.

Answer 43

The needle is placed 1cm lateral to the orbital rim, and 2 to 4mL of anesthetic is injected deep on the periosteum just lateral to the superolateral and inferolateral orbital rim. The disadvantages of this block include discomfort, proximity to the eye, and postoperative ecchymoses

Answer 44

Akinesia of the orbicularis muscle, which is supplied by the facial nerve, can be achieved by blocking the nerve at its terminal branches (modified van Lint block), superior branches (Atkinson block), or proximal trunk (O’Brien or Nadbath block).

Answer 45

The needle is inserted at the inferior margin of the zygomatic bone below the lateral margin of the orbit and 3 to 4mL of anesthetic solution is injected as the needle is advanced upward and temporally across the bone at 30 degrees from the vertical.

Answer 46

A 12-mm, 25-gauge needle is inserted perpendicular to the skin between the mastoid process and the posterior border of the mandible. The needle is advanced its full length, and after careful aspiration, 3mL of anesthetic is injected as the needle is withdrawn. This blocks the entire trunk of the facial nerve. The patient should be told to expect a lower facial droop for several hours postoperatively. The major disadvantage to this block is the proximity of the injection to important structures, such as the carotid artery and the glossopharyngeal nerve.

Answer 47

For local anesthesia, a 1:1 ratio of bupivacaine 0.75% and lidocaine 2% without epinephrine is administered. Hyaluronidase is added to speed tissue penetration. Hyaluronidase can also be important in preventing anesthetic-related damage to the extraocular muscles. A human recombinant brand of hyaluronidase (Hylenex) is commercially available.

Answer 48

MAC with regional anesthesia provides many advantages over general anesthesia in lowering postoperative morbidity, mortality, and pulmonary omplications. There is better postoperative pain control, a lower incidence of intraoperative hypotension, faster postoperative recovery, less PONV, and fewer unplanned hospital admissions

Answer 49

5: Responds to name spoken in normal tone / Normal speech / Normal Facial Expression / Clear eyes 4: Lethargic response to name spoken in normal tone / Mild slowing or thickening of Speech / Mild relaxation on Facial Expression / Glazed mild ptosis 3: Responds only after name spoken loudly or repeatedly / Slurring or slowing sppeech / Marked relaxation on Facial Expression / Glazed marked ptosis 2: Responds after mild prodding or shaking / Few recognized words 1: Does not respond to mild prodding or

Answer 50

2 to 3 hours enucleation, dacryocystorhinostomy, orbital decompression, scleral buckle, and radioactive plaque implantation ketamine and dexmedetomidine

Answer 51

0.5 to 0.7 mcg/kg 2 to 3 hours

Answer 52

strabismus repair, scleral buckle, orbitotomy, enucleation, glaucoma, and cataract surgery

Answer 53

IOP hemorrhage in both intraocular and extraocular surgery

Answer 54

penetrating keratoplasty, deep anterior lamellar keratoplasty, combined corneal transplantation and vitrectomy, and some vitreoretinal procedures requiring muscle relaxation penetrating keratoplasty loss of ocular contents or choroidal hemorrhage

Answer 55

sulfur hexafluoride (SF6), or octafluoropropane (C3F8)

Answer 56

10 neurofibromatosis, rubella, or Sturge–Weber syndrome (congenital capillary hemangiomatosis)

Answer 57

50 age over 3 years, duration of surgery greater than 30 minutes, and a history of POV or PONV in the patient, sibling, or parent 30 55 70

Answer 58

2 a 5-HT3 antagonist and a steroid

Answer 59

the oculorespiratory reflex (ORR) leads to bradypnea and respiratory pauses. The afferent limb is the same as for the OCR; the efferent limb has not been clearly established. It is not responsive to anticholinergics. The ORR may be less appreciated because of the use of assisted modes of ventilation commonly used during strabismus surgery. Airway management is typically with an LMA unless a contraindication is present.

Answer 60

Gestational age and low birth weight anemia, sepsis, and bronchopulmonary dysplasia (BPD) 30 1500

Answer 61

Succinylcholine, used as part of a rapid-sequence induction of anesthesia to permit rapid intubation and airway protection, causes a modest increase in IOP of 8 to 10mm Hg. There has been long-standing controversy surrounding the use of succinylcholine based primarily on anecdotal reports of vitreous loss during open eye surgery. There have been a number of studies where no extrusion of ocular contents has occurred following succinylcholine use. There are also no claims for such injury since 2000 in the ASA Closed Claims Project that is designed to detect patterns of injury during anesthesia. It should be stressed that during induction of anesthesia, there are many factors that may increase IOP such as crying, coughing, bucking, or straining, particularly during suboptimal intubating conditions. All these events increase IOP significantly more than succinylcholine. Based on the current evidence, succinylcholine may be used to facilitate endotracheal intubation in open eye injuries, despite its effect on IOP.

Answer 62

13 Dexmedetomidine

Answer 63

patient movement such as bucking or coughing

Answer 64

1) Occlusion of the retinal vessels can result in interruption of the arterial supply: This process occurs most commonly from increased intraocular pressure (IOP) resulting from external pressure during surgical positioning. Other causes of increased IOP include processes within the globe such as vitreous hemorrhage and thrombotic or embolic processes that may result in occlusive disease of the retinal vasculature. 2) Ischemic optic neuropathy (ION): ION is the most frequently reported condition associated with permanent POVL. ION is caused by any process that leads to inadequate delivery of oxygen to the optic nerves, including low mean arterial pressure (MAP), cardiac and spine surgeries, prone positioning, vasculature vasoconstriction due to hypocarbia, or factors affecting oxygen delivery such as decreased cardiac output, worsening anemia, or hypoxia. 3) Cortical blindness: Cortical blindness results from a stroke in the parietooccipital areas of the cortex responsible for reception and integration of visual input. Etiologies include hypoxic and/or ischemic events such as hypoperfusion injuries as well as thrombotic and embolic events. Shen et al. reported that patients younger than 18 years undergoing spine surgery had the greatest risk of developing POVL and cortical blindness, in particular 4) Central retinal artery occlusion (CRAO): Central retinal artery occlusion is an ocular emergency and is the equivalent of a cerebral stroke. Patients typically present with profound, acute, painless monocular visual loss. Patients with CRAO usually present with sudden and profound unilateral loss of vision. More than 90% of CRAOs are non-arteritic in origin. Ipsilateral carotid artery atherosclerosis or branch retinal artery occlusion are the most common causes of CRAO. Other causes of CRAO include cardiogenic embolism, hematologic hypercoagulable states, and vascular diseases

Answer 65

There are two types of ION. Anterior ION (AION) is caused by acute disruption of the blood supply to the posterior ciliary body and characterized by swelling of the optic nerve head. Posterior ION (PION) occurs when there is ischemia due to compromise of blood supply to watershed areas in the posterior aspect of the optic nerve. Clinical findings include unilateral or bilateral visual acuity or visual field changes, an afferent pupillary defect, and an abnormal-appearing optic nerve when the ION is anterior

Answer 66

systemic hypertension, diabetes mellitus, hyperlipidemia, hypercoagulable disorders, sleep apnea, anemia, smoking, age over 50 years, peripheral vascular disease, coronary artery disease, and obesity prone position, prolonged surgical duration, substantial blood loss, and prolonged use of intraoperative vasoactive agents in high-risk patients.

Anesthesia for Ophthalmic Surgery Flashcards

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