ENT Flashcards
- The most accurate statement regarding absorption of topically administered ophthalmic drugs is that they are absorbed
A. Slower than subcutaneous
absorption
B. Faster that intravenous absorption
C. Similar to oral absorption
D. Slower than intravenous absorption
D. Topically applied drops are quickly absorbed by the mucosal lining of the nasolacrimal duct as well as by blood vessels in the conjunctival sac with a potential to produce systemic effects. Absorption is rapid, faster than oral or subcutaneous administration, but still slower than intravenous.
Drainage of aqueous humor occurs at all of these sites, except
A. Canal of Schlemm
B. Trabecular network
C. Episcleral venous system
D. Tear ducts
- D. Intraocular pressure (IOP) is a reflection of the eye’s ability to form and drain aqueous humor. The posterior chamber’s ciliary body is the major producer of aqueous humor. Obstruction of the drainage system, whether it is at the canal of Schlemm, the trabecular network, or the episcleral venous system, will elevate IOP. Tear ducts do not contribute to the drainage of aqueous humor.
The normal intraocular pressure (IOP) is _______ (mm Hg):
A. 5
B. 10
C. 25
D. 30
- B. Normally, IOP of the eye varies between 10 and 22 mm Hg, and is generally considered abnormal when >25 mm Hg. This pressure is not static, as it can vary by 1 to 2 mm Hg with each cardiac contraction. Diurnal variations of up to 5 mm Hg also exist, with a higher pressurenoted upon awakening.
- Correct consequence of respiratory variables on intraocular pressure (IOP) is
A. Decrease in Pa O 2 will decrease IOP
B. Increase in Pa O 2 will decrease IOP
C. Decrease in Pa CO 2 will increase IOP
D. Increase in Pa CO 2 will increase IOP
- D. Hypoventilation (↑Pa CO 2 ) along with hypoxemia (↓Pa O 2 ) will result in increased IOP, whereas hyperventilation (↓Pa CO 2 ) will serve to minimize choroidal blood flow to decrease IOP. Hyperoxemia (↑Pa O 2 ) does not affect IOP significantly.
- All of the following will serve to decrease intraocular pressure (IOP), except
A. Nitrous oxide
B. Acidosis
C. Morphine
D. Vecuronium
- B. Inhaled and injected anesthetics (with the exception of ketamine) along with opioids tend to lower IOP. Nondepolarizing muscle relaxants will decrease IOP, presumably via their relaxant effects on extraocular muscles. Hypoventilation (↑Pa CO 2 ) results in respiratory acidosis, which will increase IOP (Table 16-2).
- Increases in intraocular pressure (IOP) following succinylcholine administration for tracheal intubation can be minimized by all of the following, except
A. β-Adrenergic blocker
B. Nondepolarizing relaxant
C. Detachment of extraocular muscles from the globe
D. Lidocaine
- C. The use of succinylcholine for eye surgery is controversial. Succinylcholine can increase IOP by about 5 to 10 mm Hg for about 5 to 10 minutes after intravenous administration (longer duration of ↑IOP following intramuscular administration). Pretreatment with nondepolarizing muscle relaxants, lidocaine, or β-blockers may reduce the ocular hypertensive response to minimize increases in IOP. The increase in IOP after succinylcholine persists whether or not the extraocular muscles are intact, suggesting that cycloplegic effects, rather than physical contraction, are responsible for IOP elevation
- The ocular effects of ketamine includes
A. Pupillary constriction
B. Blepharospasm
C. Decrease in intraocular pressure
D. Myoclonus
- B. Ketamine may cause nystagmus and blepharospasm and may not be suitable for ophthalmic surgery. Studies with respect to the effect of ketamine on intraocular pressure (IOP) have shown conflicting results, but it appears more likely to increase, as opposed to decrease, ocular pressures. This may depend on whether ketamine is administered through the IM or IV route. Ketamine is not known to affect pupil size. Myoclonus is commonly associated with etomidate and likely should also be avoided when IOP control is essential.
- An 82-year-old female patient who resides in a nursing home facility presents for breast biopsy. She states that she uses eye drops to treat glaucoma, but does not know exact names. Patient denies other medical issues, however states that she frequently has acid reflux. Potential anesthetic considerations as a result of eye drops include all of the following, except
A. Hyperchloremic metabolic acidosis
B. Hypokalemic metabolic acidosis
C. Prolonged neuromuscular block with succinylcholine
D. Atropine-resistant bradycardia
- A. Topical ophthalmic medications undergo sufficient and prompt absorption to produce systemic effects and may cause adverse cross-reactions to medications used in routine anesthesia care. Acetazolamide drops, due to its action as a carbonic anhydrase inhibitor, can induce a hypokalemic metabolic acidosis. Topical echothiophate iodine, an irreversible cholinesterase inhibitor, can reduce plasma cholinesterase activity, prolonging the duration of action of succinylcholine and mivacurium. Absorption of timolol, a nonselective β-adrenergic blocker has been associated with atropine-resistant bradycardia, hypotension, and bronchospasm during general anesthesia. Hyperchloremic acidosis is largely related to large volume resuscitation with normal saline.
- An air bubble is injected into the posterior chamber at the conclusion of retinal surgery (pneumatic retinopexy) to facilitate anatomically correct healing. The most appropriate anesthetic management, before the air bubble is injected, is
A. Increase depth of anesthesia
B. Discontinue nitrous oxide (N 2 O)
C. Ensure adequate muscle relaxation
D. Hyperventilate the patient
- B. In the presence of N 2 O, air bubbles will increase in size as N 2 O is 35 times more soluble compared to molecular nitrogen (the major component of air), allowing it to diffuse into an air bubble more rapidly than nitrogen is absorbed out of the bubble. If the bubble expands after the incision is closed, intraocular pressure will rise. This complication can be avoided by discontinuing N 2 O at least 15 minutes prior to the bubble injection, as the washout of N 2 O from the lungs is 90% complete within 10 minutes. Additionally, repeat general anesthesia with N 2 O should be avoided until the bubble is fully absorbed, which for air can take up to 5 days.
- Compared with air, sulfur hexafluoride (SF 6 ) bubble injected following vitreous surgery
A. Has a longer duration of action
B. Is more soluble in blood than nitrogen
C. Is inert and will not expand
D. Is contraindicated in outpatient surgery
- A.SF 6 is an inert gas that is much less soluble than nitrogen (the major component of air) in blood and, therefore, will have a longer duration of action (10 days) compared to an air bubble. Bubble size doubles within 24 hours after injection of SF 6 because nitrogen from inhaled air will enter more rapidly into the bubble than sulfur can diffuse out of it. This slow bubble expansion usually does not pathologically affect IOP. However, inspired N 2 O, which is 117 times more diffusible than hexafluoride (compared to 35 times more than nitrogen), will rapidly enter the SF 6 bubble such that IOP will rise significantly within 30 minutes after the eye is closed. As with air, repeat general anesthesia with N 2 O should be avoided until the SF 6 bubble is fully resorbed.
A 22-month-old 14.5-kg “preemie” is undergoing strabismus repair under general endotracheal anesthetic (GETA). Following an uneventful inhaled induction with sevoflurane, peripheral IV was obtained, and by oversight, patient was given 20 mg of succinylcholine prior to intubation. Masseter spasm was noted moments later.
11. What parameter is considered the earliest sign and symptom of an ensuing hypermetabolic state following succinylcholine administration?
A. Hyperthermia
B. Hypotension
C. EtCO 2 increase
D. Low oxygen saturation
- C.Although still quite rare, an increased incidence of malignant hyperthermia (MH) has been reported in patients with strabismus (underlying myopathy) such that a high index of suspicion should be maintained. EtCO 2 is considered the earliest indicator of a hypermetabolic state with unexpected increases in CO 2 despite constant minute ventilation. Avoiding known triggers can negate the risk of inducing MH, such that succinylcholine is not recommended during strabismus surgery involving infants and children.
A 22-month-old 14.5-kg “preemie” is undergoing strabismus repair under general endotracheal anesthetic (GETA). Following an uneventful inhaled induction with sevoflurane, peripheral IV was obtained, and by oversight, patient was given 20 mg of succinylcholine prior to intubation. Masseter spasm was noted moments later.
12. Midway through the surgery, when surgical traction in the operative field is applied, patient’s heart rate plummets from 110 bpm down to 55 bpm. The pairing that accurately reflects the afferent and efferent limbs, respectively, of this reflex is
A. Trigeminal nerve vagus nerve
B. Optic nerve vagus nerve
C. Vagus nerve trigeminal nerve
D. Trochlear Nerve optic nerve
- A.Trigeminovagal reflex: the afferent limb of the oculocardiac reflex is via the trigeminal nerve (CN V), primarily through the ophthalmic division (V1). The impulse travels along the long and short ciliary nerves (LCN and SCN) to synapse on the ciliary ganglion. The impulse then continues through the trigeminal ganglion arriving at the sensory nucleus of the trigeminal nerve. The convergence between the afferent and efferent limbs is at the motor nucleus of the vagus nerve (CN X) of the brain stem. From here, the efferent limb is via the vagus nerve, which eventually synapses on the sinoatrial node of the heart, resulting in an abrupt bradycardia (Fig 16-1).
A 22-month-old 14.5-kg “preemie” is undergoing strabismus repair under general endotracheal anesthetic (GETA). Following an uneventful inhaled induction with sevoflurane, peripheral IV was obtained, and by oversight, patient was given 20 mg of succinylcholine prior to intubation. Masseter spasm was noted moments later.
13. The most appropriate first step in the management of this hemodynamic instability is
A. Epinephrine
B. Atropine
C. Remove traction
D. Phenylephrine
- C.The oculocardiac reflex (OCR) occurs frequently during strabismus surgery. It can occur following traction of the extrinsic eye muscles, or placement of pressure on the globe. The OCR is most commonly manifested as bradycardia, which regresses almost immediately after the stimulus is removed. Bigeminy, ectopy, nodal rhythms, atrioventricular block, and cardiac arrest have also occurred. Traction on any of the extraocular muscles can evoke this reflex, but it appears that manipulation of the medial rectus muscle is the most consistent trigger. Though the prophylactic use of an anticholinergic (atropine or glycopyrrolate) before the potential evoking stimulus may be recommended, the most effective treatment is the removal of the stimulus.
A 22-month-old 14.5-kg “preemie” is undergoing strabismus repair under general endotracheal anesthetic (GETA). Following an uneventful inhaled induction with sevoflurane, peripheral IV was obtained, and by oversight, patient was given 20 mg of succinylcholine prior to intubation. Masseter spasm was noted moments later.
14. At the conclusion of the surgery, postoperative nausea and vomiting should be anticipated and can be minimized by all of the following, except
A. Serotonin (5-HT 3 ) antagonist
B. Propofol infusion
C. Limiting opioids
D. Deep extubation
- D.The incidence of nausea and vomiting following strabismus surgery can be high, ranging anywhere from 48% to 85%. Minimizing the use of opioids, substituting propofol for inhaled anesthetics, along with the prophylactic use of antiemetics can reduce nausea and vomiting after surgery. Deep extubation has no impact on postoperative nausea and vomiting, and may place patient at risk for aspiration.
- The true statement regarding an oculocardiac reflex is
A. It does not occur in enucleated patients
B. Incidence is increased in the setting of hypercarbia
C. Intensity increases with repeated stimulation
D. Suppressed by general anesthesia
- B.The afferent limb of the oculocardiac reflex (OCR) is the trigeminal nerve such that pressures on the globe, conjunctiva, or orbital structures and traction on the extraocular muscles are potential triggers. This reflex occurs even with an empty globe. Hypercarbia and hypoxemia are factors believed to augment the incidence and severity of the reflex. This reflex is noted to fatigue with repeated stimulation and is not suppressed by general anesthesia.
- All of the following anatomic structures may participate in triggering an acute and abrupt bradycardia during ophthalmic surgery, except
A. Trigeminal nerve
B. Vagus nerve
C. Globe
D. Optic nerve
- D.The afferent limb of the oculocardiac reflex is the trigeminal nerve such that triggers include pressure on the globe, conjunctiva, or orbital structures as well as traction of the extraocular muscles. The vagus nerve is the efferent limb with connections to the sinoatrial node triggering a reflex bradycardia. The optic nerve is not involved in this reflex activity
- Appropriate anesthetic management for ophthalmic surgery requires tight control of intraocular pressure (IOP) before, during, and after the procedure. The accurate effect of an anesthetic drug or maneuver on IOP is
A. Decreased by glycopyrrolate
B. Increased by hyperventilation
C. Decreased by nitrous oxide
D. Increased by nondepolarizing muscle relaxants
- C.Anticholinergics (e.g.,glycopyrrolate) may include mydriasis of the pupils, leading to an increase in intraocular pressure. Unlike atropine, however, glycopyrrolate is completely ionized at physiologic pH; thus, the occurrence of CNS-related side effects is lower, as it has difficulty crossing the blood–brain barrier. Anesthetic agents, whether inhaled or injected, reduce IOP, with the possible exception of ketamine. Nondepolarizing neuromuscular-blocking agents produce a slight decrease, while depolarizing relaxants increase IOP. Hyperventilation will cause vasoconstriction with decreasein choroidal blood flow and intraocular pressures.
- All these nerves can be disrupted by injection of local anesthetics into the retrobulbar space, except
A. Optic nerve
B. Oculomotor nerve
C. Trochlear nerve
D. Abducens nerve
- C.Nerves blocked are those within the optic cone (annulus of Zinn), which include optic (CN II), oculomotor (CN III), and the abducens (CN VI). The trochlear nerve (CN IV) is not affected, since it is located outside of this muscle cone.
- When compared to an adult, the airway anatomy of a 6-week-old infant reveals
A. Tongue is smaller and floppy
B. Airway is narrowest at theglottic opening C. Position of the larynx is more anterior in the neck
D. Epiglottis is flat and firm
- C.Recognizing the anatomical differences between an adult and a pediatric airway is important. One of the most obvious differences is the tongue itself. The pediatric tongue is larger, in relation to the amount of free space in the oropharynx, when compared to the adult tongue. With regards to the pediatric epiglottis, it tends to be large and floppy with a more oblong configuration, making epiglottis control with a laryngoscope blade more challenging. Additionally, the position of the adult larynx is at about the level C5–C6; the pediatric larynx is more cephalad, at about the level of the C3–C4. This is an important anatomical airway consideration, since the higher larynx tends to be more anterior as well (Fig 16-2).
A 35-year-old male with a toxic multinodular goiter presents for thyroidectomy with radical neck dissection. He denies any other significant medical history. Review of systems reveals orthopnea and dysphagia with a recent change in the caliber of his voice.
39. True statements about this patient include all of the following, except
A. A flow–volume loop on spirometry can evaluate tracheal compression
B. The airway may obstruct with sedation
C. The trachea may collapse postoperatively
D. An abnormally low forced expiratory volume in 1 second (FEV 1 ) would be diagnostic of an upper airway obstruction
D.The configuration of the flow–volume curve during spirometry testing can be used to demonstrate abnormalities of the larger central airways (larynx, trachea, and main stem bronchi). The FEV 1 /FVC ratio can provide diagnostic value, as disproportionate reduction in the FEV 1 as compared to the FVC is the hallmark of obstructive lung diseases. Concern should be made regarding airway collapse following sedation or induction of anesthesia when extrathoracic lesions are present. If long-standing, tracheomalacia may leave the trachea weak and collapsible postoperatively (Fig 16-3).
- To attenuate risk of a “cannot ventilate, cannot intubate” scenario, an awake airway intubation is discussed. The neural structure that does not need to be blocked in order to provide adequate airway analgesia for a nasal intubation is
A. Hypoglossal nerve
B. Sphenopalatine ganglion
C. Superior laryngeal nerve
D. Recurrent laryngeal nerve
- A.Anesthesia of the nasal mucosa and nasopharynx is achieved via blockade of trigeminal branches, particularly the sphenopalatine ganglion and ethmoid nerves. Blockade of the glossopharyngeal and superior laryngeal nerves provide anesthesia to the mouth, oropharynx, and base of the tongue. The hypopharynx, larynx, and trachea are innervated via a branch of the vagus nerve (CN X), specifically the recurrent laryngeal nerve, which can be blocked via a transtracheal approach. On the other hand, blockade of the hypoglossal nerve (CN XII) will only serve to paralyze the intrinsic muscles of the tongue without adding to anesthesia of the airway (Fig 16-4).
- If bilateral recurrent laryngeal nerves were unintentionally severed, the likely finding on direct laryngoscopy would be
A. Paralysis of the cricothyroid muscles
B. Intermediate position of the cords
C. Midline, closed position of the cords
D. Pure adductor vocal cord paralysis
- B.The recurrent laryngeal nerves provide motor innervation to all the intrinsic muscles of the larynx, except the cricothyroid muscle, which is innervated by the superior laryngeal nerve. Damage to bilateral recurrent laryngeal nerves will affect abduction and adduction of the cords, resulting in both vocal cords adopting an intermediate, or paramedian, position. Patient would also have associated aphonia with risk of airway obstruction with inspiration as the cords flap together. Unilateral damage will present with hoarseness.
- Instead, postoperative direct laryngoscopy reveals normal position of the cords at rest, widely open glottic opening at maximal inspiration, and symmetrically moving cords during quiet breathing but with weak phonation and inability to speak loudly or shout. The most likely etiology is
A. Recurrent laryngeal nerve paralysis
B. Superior laryngeal nerve (SLN) paralysis
C. External airway compression
D. Vagus nerve paralysis
- B.In the case of lesions to the SLNs, adduction and abduction of the vocal cords remain intact. SLN lesions instead lead to weak tensor strength (cricothyroid muscle), leaving the voice hoarse, weak, breathy, and with the inability to scream or shout. Other associated findings would be loss of sensation above the cords, leaving patient vulnerable to inhalation of any material present in the pharynx.
A 27-year-old male arrives to the operating room with laryngotracheal injuries stemming from a motorcycle collision. He presents with hoarseness and dyspnea while sitting, but is unable to lie flat due to worsening dyspnea. He is unable to swallow, and is drooling/spitting moderately blood-stained sputum. His anterior neck is diffusely swollen and exquisitely tender with notable subcutaneous emphysema. Oxygen saturation is 100% with supplemental oxygen via face mask. Review of imaging reveals a thyroid cartilage fracture horizontally and crossing the midline
45. His injury would be consistent with trauma to this zone of his neck:
A. Zone I
B. Zone II
C. Zone III
D. Zone IV
- B.The neck is divided into three zones: zone I, including the thoracic inlet, up to the level of the cricothyroid membrane, is treated as an upper thoracic injury. Zone III, above the angle of the mandible, is treated as a head injury. In this case, fracture of the thyroid cartilage represents an injury of the neck in zone II. For ease of memory, consider that the cricoid cartilage demarcates the border between zones I and II and the angle of the mandible separates zone II from zone III (Fig 16-5).
During thyroidectomy for carcinoma, a 22-year-old patient develops tachycardia to 115 bpm while blood pressure intensifies to 145/100 mm Hg. The inhaled anesthetic is deepened and minute ventilation is increased. Thirty minutes later, tachycardia and hypertension persists despite all efforts46. The appropriate treatment to consider at this time is
A. Propranolol
B. Acetaminophen
C. Iodine
D. Dantrolene
- D.Increasing EtCO 2 andtemperature may reveal possible malignant hyperthermia. With onset of cardiac arrhythmias, and the increasing likelihood of the development of malignant hyperthermia with rapidly climbing EtCO 2 and hyperthermia, treatment with dantrolene should be considered and pursued. Other signs that can strengthen the diagnosis are muscle rigidity and myoglobinuria.
