Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
94 Cards in this Set
- Front
- Back
|
Function of the orbit |
To protect eyeball and surrounding structures
|
|
|
What travels through the optical foramen? |
Optic nerve Optic artery Optic vein Sympathetic nerves |
|
|
Sympathetic innervation of the eye comes from where? |
Carotid plexus |
|
|
_____________ is the outermost portion of the eye |
the sclera |
|
|
The anterior portion of the scleara is _______ and is known as the ______ |
transparent known as the cornea |
|
|
The middle layer of the eye is known as the ________ |
choroid |
|
|
What structures are found within the choroid? |
Iris, ciliary body, choroid |
|
|
The iris dilator is under control of the __________ nervous system. Dialation of the eye is known as ________ |
Sympathetic nervous system Mydriasis |
|
|
The iris constrictor and ciliary muscles are controled by the ___________ nervous system. Constriction of the pupil is known as _________ |
Miosis |
|
|
Photoreceptors on ________ convert light into nerual impulses. These impulses are carried to the brain via _______ |
The retina Optic nerve |
|
|
What is the name for the covering of the surface of the globe? What is it made of |
The conjunctiva Very absorbant membrane - also lines the eyelids |
|
|
Blood flow to the eye comes from which vessels |
Internal and external carotid arteries. |
|
|
Venous drainage of the orbit is via _______ |
superior and inferior opthalmic veins |
|
|
Drainage of the eye is via _______ |
the central retinal vein |
|
|
All veins from the eye empty into _________ |
the cavernous sinuses |
|
|
Sensory and motor innervation of the eye come from which four cranial nerves? |
(III) Oculomotor - ciliary gangleon, pupil sphincter and ciliary muscle (IV) Trochlear- superior oblique muscle (VI) Abducens - lateral rectus muscle (V) Trigeminal (V1 opthalmic) (VII) Facial |
|
|
Where is the aqueous humor formed? |
1/3 formed in posterior chamber 1/3 formed from vessels of iris (passive filtration) -2.5 microliters/min -total volume =250 microliters |
|
|
How is aqueous humor formed |
Carbonic anhydrase & cytochrome oxidase systems At ciliary epithelium Na+ is actively transported into aqueous humor HCO3- and Cl- follow |
|
|
Aqueous humor osmotic pressure is (greater/less) than plasma pressure |
Greater |
|
|
Describe the flow of aqueous humor. |
Ciliary body Posterior chamber (via pupil) Anterior chamber Drains to venous system (canal of Schlemm) |
|
|
Normal IOP |
10-22 mmHg |
|
|
Positional changes increase IOP by how much |
1-6 mmHg |
|
|
Acute rise in IOP causes _________ |
acute glaucoma |
|
|
Once the eye cavity is entered, the IOP becomes _________ |
atmospheric |
|
|
Under anesthesia acute increase in IOP can cause ___________ |
permanent loss of vision |
|
|
Three main factors that affect IOP |
External pressure on eye Scleral rigidity Changes in intraocular contents |
|
|
Anesthetic affects on IOP |
Laryngoscopy/intubation (elevate) Hyperventilation (decreases) Hypoventilation (increases) Hypothermia (decreases) Inhalation agents (decrease) Etomidate (decreases) Ketamine (increases) Non Depolarizing NMBA (reduces) Succinylcholine (increases) |
|
|
Caution should be taken with a ruptured globe when using which induction agent? |
Etomidate |
|
|
The use of ketamine is ___________ |
controversial |
|
|
Affect of succinylcholine on the IOP |
Tonic contractions of extraocular muscles Choroidal dilation of vasculature Relaxation of orbital smooth muscle Increases resistance of outflow of aquous humor |
|
|
Succinylcholine can increase IOP by _______ |
10-20 mmHg |
|
|
What type of eye injury makes succinylcholine contra-indicated? Can it ever be used in this situation? |
Open globe injury - extrusion of aquous humor Pretreat with (nodepolarising NBMA, benzo, beta blocker, acetazolamide) |
|
|
What type of surgery should succinylcholine be avoided in? |
Strabismus surgery |
|
|
Affect of trimethaphan on IOP |
Decreases |
|
|
Affect of acetazolamide on IOP |
decreases - reduces formation of aqueous humor |
|
|
How do hypertonic solutions decrease IOP? -dextran -mannitol -sorbitol -urea |
Elevate plasma oncotic pressure, which reduces formation of aqueous humor
|
|
|
What is the occulocardiac reflex |
Pressure on the globe or traction on the extraocular muscles cause bradycardia. |
|
|
Nerves involved in occulocardiac reflex -afferent -efferent |
afferent = trigeminal (V) efferent = vagus (X) "5 and dime" reflex |
|
|
Three causes of the oculocardiac reflex |
Retrobulbar block Ocular trauma Direct pressure on remaining tissue following enucleation. |
|
|
What factors can increase the risk of oculocardiac reflex? |
Hypercapnia Hypoxemia Acute onset, strong, sustained traction |
|
|
Treatment for oculocardiac reflex |
Stop stimulation Assess anesthetic depth/ventilation Atropine Lidocaine infiltration at site |
|
|
Uses of Acetylcholine in eye procedures |
Lens extraction |
|
|
Effects of Acetylcholine |
Miosis Systemic effects -bradycardia -salivations -bronchial secretions -bronchospasm -hypotension |
|
|
Echothiophate -indication -effects |
Glaucoma treatment Effects -miosis -decreased IOP -decreased resistance to aqueous humor -irreversible cholinesterase inhibitor (5% of normal activity, SCh/ester locals contraindicated) --normalizes after 4-6 weeks |
|
|
Cocaine -indications -effects |
Nasal packs Effects -vasoconstriction -blocks reuptake of NE -potentiates SNS Avoid sympathomimetics |
|
|
Epinephrine -uses -effects |
Open angle glaucoma treatment Effects -anxiety -angina -tachycardia |
|
|
Phenylephrine |
Mydriasis Capillary decongestant Systemic effects (rare) -HTN -Tachycardia -headache -tachycardia -tremulousness |
|
|
Timolol |
Glaucoma treatment -dec IOP (dec. aqueous humor prod.) -Nonselective B-blocker Systemic effects -bradycardia -hypotension -asthma exacerbations -myasthenia gravis exacerbation |
|
|
Betaxalol |
Glaucoma treatment -B-1 antagonist (selective) -minimal systemic effects |
|
|
Cyclopentolate |
Anticholinergic -mydriasis -CNS toxicity (dysarthria, disorientation, sz, psychosis in children) |
|
|
Effect of retrobulbular block |
Ciliary nerve Causes akinesia of eyelid |
|
|
____________ is added to retrobulbular block to enhance absorption |
hyaluronidase |
|
|
What is a honan cuff? |
Orbital compression baloon -decreases IOP -enhances periorbital spread of local |
|
|
Complications of retrobulbular block (6) |
Optic nerve trauma Retrobulbular hemorrhage Increased IOP Oculocardiac reflex Intravascular injection Apnea |
|
|
Advantages of retrobulbular block (5) |
Analgesia Akinesia Decreased incidence of coughing/straining Decreased incidence of PONV SDS patients (minimal sedation required) |
|
|
Direct injection or spread of local anesthetic along optic nerve sheath to CSF can cause what? |
Brainstem anesthesia -apnea -anxiety -may require intubation -resolves within 1 hour |
|
|
A retrobulbular hemorrhage can cause forward bulging of the eye known as __________ |
proptosis |
|
|
Treatment for retrobulbular hemorrhage |
Gentle pressure for 20 min Reschedule surgery -severe cases may require lateral canthotomy to relieve optic nerve compression |
|
|
Advantages/disadvantages of topical anesthesia to the eye |
Blocks sensory innervation to cornea Easy to apply Eye movement still possible Anxiety possible Allergic reactions can occur |
|
|
Ketamine can cause ___________, and should be avoided in eye surgeries |
Nystagmus |
|
|
In an open globe injury, IOP is _________ |
atmospheric |
|
|
Anesthetic considerations for open globe injury |
Trauma pt (exclude other injuries, full stomach) Prevent sudden increase in IOP (sedative + nondepolarizer) (succinylcholine + pretratment) Awake extubation |
|
|
Anesthetic considerations for straibismus surgery |
Most common pediatric opthalmic procedure Triggers oculocardiac reflex Increased MH (underluing myopathy) LMA Smooth emergence/deep extubation |
|
|
Why should succinylcholine be avoided with strabismus surgery? |
Tonic contractures of extra-ocular muscles Interferes with forced duction test |
|
|
What is the oculogastric reflex |
Frequent PONV associated with eye surgery |
|
|
Four examples of intra-ocular surgery |
Glaucoma drainage Vitrectomy Keratoplasty (corneal transplant) Catract extraction |
|
|
Anesthesia considerations for intra-ocular surgery |
General/block Antiemetics Paralysis (nondepolarizers) Akinesia Avoid hypercarbia Deep extubation (IV lidocaine 1-1.5 mg/kg) |
|
|
__________ is injected into the eye for retinal detachment surgery |
Air/gas/silicone bubble |
|
|
Anesthetic considerations for retinal detachment surgery |
No N2O for 30 days Mannitol/acetazolamide Oculocardiac reflex No muscle relaxation required |
|
|
Inspiratory stridor is indicative of ___________ airway obstruction |
upper |
|
|
Expiratory stridor is indicative of __________ airway obstruction |
lower |
|
|
Jet ventilation requires pressures of _____ to ______ psi |
30-50 |
|
|
Contraindications to jet ventilation |
Pediatrics (barotrauma) Obese patients (unable to oxygenate) Bullous emphysema (risk of rupture) |
|
|
Advantages of laser laryngoscopy |
Increased precision Less bleeding Rapid healing |
|
|
Safety precautions for laser procedures |
Saline soaked eye pads/goggles Laser masks Must use muscle relaxants Laser tube Fill cuff with liquid No N2O, FiO2 < 30 |
|
|
Steps to take if airway fire |
Stop ventilation
Turn off O2 Remove ETT Extinguish fire Reintubate/ventilate *post op: CXR, bronchoscopy, steroids, ABG, ventilatory support |
|
|
Indications for tonsilectomy |
Snoring Frequent infections |
|
|
Anesthetic considerations for tonsilectomy |
Avoid pre-op sedation (obstruction) Steroids Oral RAE (cuffed or throat pack) Paralysis/deep anesthesia Large EBL Awake extubation Side lying position post-op |
|
|
Most common complication of tonsilectomy |
post-op bleeding |
|
|
Anesthetic considerations for bleeding tonsil surgery |
Rehydration prior to induction -1-2 large bore IVs -fluid bolus until no orthostatic changes Ketamine/etomidate Full stomach OG tube Awake extubation |
|
|
In pediatric patients hypovolemia can result in ___________ on induction |
cardiac arrest |
|
|
Should an in inhalation induction be done on pediatric bleeding tonsil patients? |
No. Risk for aspiration Need IV for rehydration |
|
|
If unable to locate glottis when intubating bloody airway - look for ___________- |
bubbles |
|
|
How might the airway appear in a patient with a tonsillar absces? |
Distorted airway -gentle intubation -avoid rupture of absces |
|
|
Health problems associated with cancer of the neck |
Chronic tobacco/EtOH use COPD CAD HTN Poor nutrition (anemia, dehydration, electrolyte) |
|
|
Pre-op studies needed for neck dissection |
ECG CXR ABG PFT Neck CT |
|
|
Nerve monitoring with neck dissection |
Facial nerve -may need to avoid muscle relaxants |
|
|
Risks associated with neck dissection surgery (5) |
air emboli pneumothorax bleeding possible tracheostomy dysrhythmias (stop manipulation, local anesthetic, atropine) -carotid sinus (vagal) -stellate gangleon (long QT) |
|
|
Anesthetic considerations for myringiotomy tubes |
Peds - inhalation anesthetic Short procedure Pain control |
|
|
Describe the differences between -LeFort I -Lefort II -LeFort III |
Lefort I = horizontal fx of lower mandible Lefort II = triangular extension of LFI -2 oblique lines along maxillary suture to floor of orbit Lefort III = transverse fracture through both orbits -separation of maxilla from skull |
|
|
______ percent of lefort II & III fractures develop dural tear resulting in what? |
25% resulting in CSF leak |
|
|
Anesthetic considerations for tracheostomy |
3rd - 4th tracheal cartilage Low FiO2 when using cautery Assure patency of trach tube before removing ETT -bilateral breath sounds -etCO2 -SPO2 |
|
|
It takes ________ days to establish a new tract in a fresh tracheostomy |
Five days |
|
|
Complications of tracheostomy (4) |
Hemorrhage False passage Airway fire Pneumothorax |
