OPHTHALMOLOGY AND OTOLARYNGOLOGY

Question 1

What is normal intraocular pressure (IOP)?

Answer 1

○ Intraocular pressure ranges between 10 to 22 mm Hg.
○ In the intact normal eye there
is a typical diurnal variation of 2 to 5 mm Hg.
○ Small changes can occur with
each cardiac contraction and with closure of the eyes, mydriasis, and changes inposture

Question 2

How is IOP created and maintained?

Answer 2

○ Intraocular pressure is primarily a balance between the production of aqueous humor and its drainage.
○ Aqueous humor is actively secreted from the posterior
chamber’s ciliary body and flows through the pupil into the anterior chamber where it becomes mixed with aqueous fluids, which are passively produced by blood vessels on the iris’s forward surface.

Question 3

Why and to what extent does IOP increase during coughing or vomiting?

Answer 3

○ Any obstruction of venous return from the eye to the right side of the heart can raise IOP.
○ Coughing or straining can increase intraocular pressure by 40 mm Hg
or more.

Question 4

What factors during the course of a general anesthetic increase IOP?

Answer 4

○ Any maneuver that increases venous congestion will increase IOP. ○ These include: Trendelenburg positioning, tight cervical collar, straining, retching, vomiting,
and coughing.
○ Direct laryngoscopy and intubation also increase intraocular pressure

Question 5

What physiological factors (CO2, temperature) during the course of a general anesthetic decrease IOP?

Answer 5

During general anesthesia hyperventilation and hypothermia decrease IOP

Question 6

How does ketamine affect intraocular pressure? What other attributes of ketamine
make it a less than ideal choice for anesthesia in patients undergoing
ophthalmologic procedures?

Answer 6

○ Ketamine can induce a rotatory nystagmus, cycloplegia, and blepharospasm (tight
squeezing of the eyelids).
○ Additionally, it is proemetic and increases secretions.
○ Anticholinergic agents may be administered with ketamine to diminish secretions.
○ There is controversy surrounding the effect of ketamine on IOP.

Question 7

How much does IOP increase with the intravenous administration of
succinylcholine? What is the duration of this effect?

Answer 7

○ Succinylcholine can produce an increase in intraocular pressure of about 9 mm Hg 1 to 4 minutes after intravenous administration.
○ This effect can last up to 7
minutes

Question 8

What is the mechanism for the increase in IOP following administration of
succinylcholine?

Answer 8

○ Increases in IOP secondary to the administration of succinylcholine are due to a number of mechanisms including tonic contraction of the extraocular muscles, relaxation of the orbital smooth muscle, choroidal vascular dilation, and cycloplegia, which impedes aqueous outflow.

Question 9

What maneuvers may attenuate the rise in IOP associated with succinylcholine use
for laryngoscopy and intubation?

Answer 9

Pretreatment with a small dose of nondepolarizing neuromuscular blocker, lidocaine, b-blocker, or acetazolamide may attenuate increases in IOP associated with use of succinylcholine prior to direct laryngoscopy and endotracheal
intubation

Question 10

How do paralyzing doses of nondepolarizing neuromuscular blocking drugs affect
intraocular pressure?

Answer 10

Nondepolarizing neuromuscular blocking drugs will decrease IOP by relaxing theextraocular muscles

Question 11

How do inhaled anesthetics affect IOP? What is the effect on IOP of most intravenous anesthetics?

Answer 11

○ Both inhaled and most intravenous anesthetics produce dose-related reductions in
intraocular pressure.
○ This is probably due to multiple mechanisms including central nervous system depression, decreased production of aqueous humor, enhanced outflow of aqueous humor, and relaxation of the extraocular muscles.
○ The effect of ketamine on IOP is controversial.

Question 12

How do changes in arterial blood pressure affect IOP?

Answer 12

○ Arterial hypertension has minimal influence on IOP.
○ Venous drainage is the key factor affecting IOP

Question 13

What topical ophthalmic medicines may be absorbed sufficiently to exert systemic effects?

Answer 13

○ Topical ophthalmic agents can be absorbed systemically via the conjunctiva or drain down the nasolacrimal duct and be absorbed through the nasal mucosa.
○ These agents include acetylcholine, anticholinesterases, cyclopentolate,
epinephrine, phenylephrine, and timolol

Question 14

What systemic effects have been attributed to the use of topical ophthalmic b-adrenergic blocking medications?

Answer 14

Topical ophthalmic b-adrenergic blocking medications may produce atropine
resistant bradycardia and bronchospasm, and exacerbate congestive heart failure.

Question 15

What are the systemic effects of topical phospholine iodide (echothiophate)?

Answer 15

○ Phospholine iodide (echothiophate) is a miosis-inducing anticholinesterase that profoundly interferes with metabolism of succinylcholine.
○ Patients with low levels of plasma cholinesterase are at risk for prolonged paralysis.

Question 16

Why is phenylephrine administered as a topical ophthalmic medicine? What systemic effect has been attributed to the topical ophthalmic application of this
drug?

Answer 16

○ Phenylephrine is an a-adrenergic that causes mydriasis (pupil dilation).
○ Systemic absorption of phenylephrine can induce transient malignant hypertension.

Question 17

Why are carbonic anhydrase inhibitors, such as acetazolamide, administered as topical ophthalmic medicines? What systemic effects have been attributed to the
topical ophthalmic application of this drug?

Answer 17

○ Acetazolamide inhibits the production of aqueous humor.
○ Its systemic effects include diuresis and hypokalemic metabolic acidosis

Question 18

What is the oculocardiac reflex? What is its reported incidence? When is it most likely to occur?

Answer 18

○ The oculocardiac reflex is a vagal-mediated response that manifests with an abrupt, profound decrease in heart rate.
○ It occurs in response to extraocular muscle traction or external pressure on the globe.
○ The reported incidence varies widely from 15% to 80%.

Question 19

When is the oculocardiac reflex most often encountered?

Answer 19

○ The oculocardiac reflex is most often encountered during strabismus surgery.
○ However, it can arise during any type of ophthalmic surgery as well as some otolaryngology procedures.
○ A regional anesthetic eye block can ablate it.
○ Paradoxically, it may be triggered during the administration of this block.

Question 20

What cardiac rhythms are likely to result from the oculocardiac reflex?

Answer 20

○ The oculocardiac reflex can manifest as a variety of dysrhythmias including junctional or sinus bradycardia, atrioventricular block, ventricular bigeminy, multifocal premature ventricular contractions, ventricular tachycardia, and asystole.

Question 21

How does arterial hypoxemia or hypercarbia affect the oculocardiac reflex? How does the depth of general anesthesia affect the oculocardiac reflex?

Answer 21

○ Hypercarbia, hypoxemia, and light planes of general anesthesia all augment the incidence and severity of the oculocardiac reflex.

Question 22

What is the first line of treatment of the oculocardiac reflex? What measures may be taken if the reflex persists?

Answer 22

○ Prompt removal of the surgical stimulus often results in rapid recovery.
○ At the first sign of any dysrhythmia, surgery must stop and all pressure on the eye or traction on extraocular muscles must be discontinued.
○ Other measures that can be taken include the administration of a parasympatholytic such as atropine or glycopyrrolate.
○ Consider increasing the depth of general anesthesia (provided that
the patient is hemodynamically stable).
○ Alternatively, infiltration of local
anesthetic attenuates recurrence of the reflex

Question 23

23. Is prophylactic use of anticholinergics fully effective in preventing the
    oculocardiac reflex? What problems may arise from use of an anticholinergic?

Answer 23

○ The prophylactic use of an anticholinergic is not 100% effective in preventing the oculocardiac reflex.
○ Side effects that may result from the use of an anticholinergic include persistent tachycardia.
○ This may have serious
consequences in geriatric patients and those with a history of heart disease

Question 24

What are some important demographic characteristics of patients scheduled for eye surgery?

Answer 24

○ Eye surgery patients are often at the extremes of age, and range in age frompremature newborns to nonagenarians.
○ Age-specific considerations such as altered pharmacokinetics and pharmacodynamics apply.
○ The elderly, syndromic pediatric patients, and premature infants commonly have comorbidities that carry important anesthesia implications.

Question 25

Should antiplatelet or anticoagulant medications be discontinued prior to
surgery?

Answer 25

○ The cessation of antiplatelet or anticoagulant drugs prior to ophthalmic surgery is controversial.
○ One must weigh the risks of intraocular bleeding versus the risks
of perioperative stroke, myocardial ischemia, or deep venous thrombosis.

Question 26

What is a key anesthetic consideration for the patient scheduled for ophthalmic
surgery with uncontrolled cough, untreated Parkinsonian tremor, severe
claustrophobia, or pathological anxiety?

Answer 26

○ An important component of the preoperative assessment is to gauge the likelihood of patient movement during surgery.
○ An inability to remain supine and
relatively still during eye surgery under monitored anesthesia care may result in eye injury with devastating long-term visual consequences.

Question 27

What are the anesthetic options for patients having eye surgery?

Answer 27

○ The anesthetic options for ophthalmic procedures include general anesthesia, retrobulbar (intraconal) block, peribulbar (extraconal) anesthesia, sub-Tenon
block, and topical analgesia

Question 28

What is the significance of the extraocular muscle cone for eye blocks?

Answer 28

○ The extraocular muscle cone separates the intraconal from the extraconal space and determines whether the local anesthetic is delivered as a retro- or peribulbar block

Question 29

What is the ultimate needle tip position for a retrobulbar (intraconal) block?

Answer 29

A retrobulbar block is accomplished by inserting a steeply angled needle into the muscle cone such that the tip of the needle is behind (retro) the globe (bulbar).

Question 30

What is the rationale behind extraconal (peribulbar) anesthesia? Where is the ultimate needle tip position?

Answer 30

○ The boundary separating the intraconal from extraconal space is porous.
○ Local
nesthetics injected outside the muscle cone diffuse inward, resulting in anesthesia of the eye.
○ An extraconal block is achieved by directing a needle with minimal
angulation to a shallow depth, such that the tip remains outside the muscle cone

Question 31

What are some complications of a retrobulbar block?

Answer 31

○ Complications of needle-based ophthalmic regional anesthesia include superficial or retrobulbar hemorrhage, elicitation of the oculocardiac reflex, intraocular
injection of local anesthetic, penetration or puncture of the globe, optic nerve trauma, intravenous injection of local anesthetic solution and resultant convulsions, central retinal artery occlusion, brainstem anesthesia, and blindness.

Question 32

What is the differential diagnosis of altered physiological status (blood pressure,
heart rate) after a needle-based ophthalmic regional eye block?

Answer 32

○ Intravenous sedation is the most common cause of altered physiologic status (blood pressure, heart rate, rhythm, ventilation) after a needle-based eye block.
○ More sinister complications are brainstem anesthesia and local anesthetic toxicity secondary to intravascular injection

Question 33

How does a sub-Tenon block differ from a needle-based eye block?

Answer 33

○ A sub-Tenon block is performed using a blunt cannula inserted into the space between the globe’s sclera and surrounding the Tenon capsule. ○ Local anesthetic injected into this space blocks the optic and ciliary nerves as they penetrate the capsule.

Question 34

Which patients are at high risk for retinal detachment?

Answer 34

○ Diabetics and patients with severe myopia are at particular risk for retinal detachment.

Question 35

What are the anesthetic considerations for patients undergoing surgery to repair
a retinal detachment?

Answer 35

○ Retinal surgery is often prolonged and associated with greater manipulation of the eye.
○ Patients may require deeper planes of general anesthesia or a dense regional block.
○ Perfluorocarbons such as sulfur hexafluoride are relatively
insoluble gases that are surgically instilled in order to tamponade the retina; these may take up to 28 days to resorb.

Question 36

When must nitrous oxide be avoided as maintenance anesthetic for patients
undergoing surgery to repair a retinal detachment? What is the risk associated
with this?

Answer 36

○ Nitrous oxide is 100 times more diffusible than sulfur hexafluoride and, therefore, can expand the size of a gas bubble.
○ This will raise IOP and may result in retinal ischemia with permanent loss of vision.

Question 37

What is glaucoma? What are its variants?

Answer 37

○ Glaucoma is a condition characterized by raised IOP, optic nerve injury, and gradual loss of vision.
○ It is thought that a sustained increase in IOP results in
diminished perfusion of the optic nerve.
○ Variants include closed angle (or acute) glaucoma and open angle (or chronic) glaucoma.

Question 38

What are the anesthetic goals in the management of glaucoma patients?

Answer 38

○ The key anesthetic goals in the management of glaucoma patients include avoiding mydriasis (by ensuring miotic drops are continued), understanding the interactions between glaucoma medications and anesthetic agents, and preventing
increases in IOP associated with the induction, maintenance, and emergence from anesthesia.

Question 39

What are some special anesthetic considerations in children undergoing
strabismus surgery?

Answer 39

○ Special considerations for children undergoing strabismus surgery include an awareness of the high incidence of intraoperative oculocardiac reflex, an increased
risk for malignant hyperthermia, and the high incidence of postoperative
nausea and vomiting.

Question 40

What is the most common reason for an inpatient admission for children following strabismus surgery?

Answer 40

The most common reason for pediatric inpatient admission following strabismus surgery is postoperative nausea and vomiting (PONV).

Question 41

What factors must be considered in the anesthetic management of patients with traumatic eye injuries?

Answer 41

○ The anesthetic plan for patients with traumatic eye injuries must balance the specific risks of increasing IOP and exacerbating the ocular insult versus anesthetizing a non fasted patient at risk for aspiration upon the induction of
general anesthesia.
○ Increasing IOP via a tightly applied facemask, laryngoscopy and intubation, or from coughing or bucking may result in extrusion of vitreous, and jeopardize ultimate visual outcome.
○ A rapid sequence induction is indicated for the non fasted patient.

Question 42

Why is “awake” endotracheal intubation hazardous for patients with open globe injuries?

Answer 42

○ Awake endotracheal intubation may be appropriate in patients with difficult airways.
○ However, in the setting of a disruptive globe increases in IOP can lead to adverse visual outcomes.
○ The risks associated with rises in IOP produced by an awake intubation must be weighed against the inherent dangers of the difficult airway.

Question 43

What anesthetic maneuvers may attenuate increases in IOP in traumatic eye injury?

Answer 43

○ It is important to avoid maneuvers that increase IOP in patients with a
traumatic eye injury.
○ The patient should be positioned in a slight anti-Trendelenburg tilt.
○ If no airway problems are anticipated, consider the rapid
sequence induction of anesthesia with a large dose of nondepolarizing
neuromuscular blocking agent.
○ The systemic hypertension and rise in IOP that follows the administration of succinylcholine can be attenuated by the preinduction administration of intravenous medications such as lidocaine and
opioids.
○ Also, pretreatment with a small dose of a nondepolarizing neuromuscular blocking agents is useful

Question 44

Is regional anesthesia contraindicated in traumatic eye injuries?

Answer 44

○ Regional anesthesia may be an option for select injuries, and in patients at higher risk from general anesthesia

Question 45

What is the most common ocular complication following general anesthesia for
non-ophthalmologic surgery? What other condition can mimic it?

Answer 45

○ The most common ocular complication following general anesthesia for non-ophthalmologic surgery is corneal abrasion.
○ It is important to remember
a painful eye may also be a manifestation of acute glaucoma

Question 46

What are clinical signs of corneal abrasion?

Answer 46

○ Mechanical damage to the eye can occur during the induction of anesthesia.
○ It can be caused by dangling eye tags, anesthesia masks, drapes, or other objects that come in contact with the open eye.
○ Abrasions can also occur secondary to the loss of the blink reflex with subsequent drying from exposure to the atmosphere and diminished tear production.

Question 47

47. What are clinical signs of corneal abrasion?

Answer 47

The clinical signs of corneal abrasion include conjunctivitis, tearing, and foreign
body sensation.

Question 48

What are some measures that can be taken to reduce the risk of corneal abrasion
in patients under general anesthesia? What are some of the potential problems
with routine use of ophthalmic ointment?

Answer 48

○ Preventative measures include gently taping the eyelid shut during mask ventilation, intubation, and thereafter.
○ Ointments may cause an allergic reaction or blur post-emergence vision.
○ Protective goggles may be beneficial

Question 49

Which surgical procedures are associated with increased risk of postoperative
visual loss?

Answer 49

○ The risk of postoperative visual loss is higher in prolonged spine surgery in the prone position, and cardiac surgery.

Question 50

What action(s) should be taken if the patient complains of postoperative
visual loss?

Answer 50

○ Early consultation with an ophthalmologist is essential when a patient complains of postoperative visual loss.
○ Funduscopic and visual field examinations may aid in diagnosis.

Question 51

51. What special airway considerations pertain to ENT surgery?

Answer 51

Since ENT surgery takes place around the head, the airway becomes relatively
inaccessible to the anesthesia provider. Furthermore, there is a real possibility of
encountering a difficult airway because of anatomic factors, surgical issues, or
underlying pathology. Attention should be directed to establishing and securing
the airway, preferably with an endotracheal tube. Also, the airway may become
compromised in the perioperative period by undetected bleeding, edema, or
surgical manipulation

Question 52

52. Why are posterior pharyngeal packs used during ENT surgery and what
    precautions are required with their use?

Answer 52

Posterior pharyngeal packs minimize the risk of aspiration by sealing the larynx
from blood that reaches the pharynx. It is vital to alert operating room personnel
of their placement, and to confirm their removal prior to extubation.

Question 53

What supplemental airway devices may be needed for a difficult airway during ENT surgery?

Answer 53

Supplemental airway devices include the video-laryngoscope or fiber-optic
bronchoscope. A tracheostomy kit may be necessary for the gravely compromised
airway. Ancillary equipment should be readied prior to the commencement of
anesthesia

Question 54

54. What is laryngospasm? How is the reflex mediated?

Answer 54

Laryngospasm is an abrupt, intense, and often prolonged closure of the larynx that
leads to compromises in ventilation and oxygenation. The reflex is mediated
through vagal stimulation of the superior laryngeal nerve. It may be precipitated
by instrumentation of the endolarynx, blood or secretions on the vocal cords,
and surgical manipulation at inadequate depths of anesthesia.

Question 55

55. What is the treatment for laryngospasm?

Answer 55

Prompt recognition and intervention is key to the treatment of laryngospasm.
Treatment modalities include administration of 100% oxygen via positive-
pressure facemask ventilation, placement of oral or nasal airways, and deepening
of anesthesia with intravenous or inhalational agents. In refractory cases, a
small dose of succinylcholine may be required.

Question 56

56. Why are children at particular risk for laryngospasm?

Answer 56

. In neonates, infants, and small children even brief laryngospasm is perilous. In this
group peripheral oxygen saturation drops rapidly because of a small functional
residual capacity and relatively high cardiac output

Question 57

Should scheduled ENT surgery be postponed if the child has an upper respiratory infection (URI)? What are the risks associated with proceeding with anesthesia in a child with an active upper respiratory infection?

Answer 57

The child with an URI is at increased risk of airway issues, notably breath holding,
oxygen desaturation, and postoperative croup. However, not all children with
an URI need their ENT surgery postponed. An assessment of the benefits of
surgery vs. the risk of airway compromise should be made. For example,
the performance of a myringotomy with placement of ventilation tubes requires
minimal airway manipulation.

Question 58

What risks are associated with general anesthesia in a patient with massive
epistaxis?

Answer 58

Massive epistaxis is often associated with ongoing hemorrhage and concealed
swallowing of blood. These patients are at high risk for regurgitation and aspiration.
Clinically, they are anxious, hypovolemic, and hypertensive. The preoperative
placement of alarge-bore peripheralintravenous cannula and adequate rehydration
are vital. Hypertension and continued hemorrhage should be anticipated

Question 59

59. What are some symptoms that may alert the anesthesiologist to the presence of obstructive sleep apnea (OSA)?

Answer 59

OSA is characterized by upper airway obstruction and disordered breathing
patterns during sleep. Symptoms include snoring, early morning headache, sleep
disturbances, daytime somnolence, and personality changes. In children
there may be behavioral and growth disturbances as well as poor school
performance

Question 60

61. What are the anesthetic implications of OSA?

Answer 60

Many patients with OSA are obese. The combination of limited mouth
opening and a large tongue may make visualization of the pharynx difficult. In
adult men the neck circumference is large, often exceeding 17 inches.

Question 61

61. What are the anesthetic implications of OSA?

Answer 61

One must anticipate difficult airway management in the OSA patient. Mask
ventilation, laryngoscopy, and intubation are often challenging. Intraoperative
hypertension is common. OSA patients are exquisitely sensitive to the effects
of hypnotics and narcotics, and may require prolonged recovery room monitoring

Question 62

62. What elements are necessary to generate an airway fire?

Answer 62

There are three key elements needed to produce an airway fire:
a. Heat or source of ignition (laser or electrosurgical unit)
b. Fuel (paper drapes, gauze swabs)
c. Oxidizer (O2, air, N2O) (4

Question 63

63. Are airway fires possible with monitored anesthesia care (MAC)?

Answer 63

During monitored anesthesia care the danger of an airway fire exists because
the heat and fuel elements are still present. It is important to remove the source of
oxidation, and discontinue delivery of supplemental oxygen

Question 64

64. What are the main anesthetic considerations for middle ear surgery?

Answer 64

There are five primary anesthetic concerns for middle ear surgery:
a. N2O—increases middle ear pressure and causes serous otitis
b. Facial nerve monitoring—avoid intraoperative neuromuscular blockade
c. Epinephrine—may precipitate acute hypertension and tachyarrhythmia
d. Smooth emergence—avoid coughing, bucking, and acute hypertension
e. Postoperative nausea and vomiting—institute prophylactic measures

Question 65

65. What effects may nitrous oxide (N2O) exert during ear surgery?

Answer 65

itrous oxide is more soluble than nitrogen in blood and diffuses into air-filled cavities. The increases in middle ear pressure may disrupt tympanoplasty grafts. Also, the acute discontinuation of N2O may produce serous otitis. Nitrous oxide should be administered in moderate concentrations (<50%), if at all.

Question 66

How is surgical identification of the facial nerve performed intraoperatively in
patients undergoing otologic surgery? How might this affect the anesthetic
management?

Answer 66

The surgeon frequently uses a facial nerve monitor to prevent trauma or accidental
incision of the facial nerve and its branches. The use of neuromuscular
blocking drugs should be curtailed in order to prevent attenuation of the monitor’s
twitch response. Succinylcholine or a single small dose of an intermediate-acting
non depolarizing neuromuscular blocking agent is preferred

Question 67

68. What concentration of epinephrine is considered safe in ear microsurgery?

Answer 67

Epinephrine is injected during ear microsurgery to decrease bleeding and improve
visualization within the surgical field. Systemic uptake may precipitate
hypertension, tachycardia, and dysrhythmias

Question 68

68. What concentration of epinephrine is considered safe in ear microsurgery?

Answer 68

Epinephrine concentrations should be limited to 1:200,000 in ear microsurgery.

Question 69

69. During otolaryngology surgery how can bleeding in the surgical field be
    minimized?

Answer 69

Maneuvers to limit bleeding in the surgical field include use of topical or injected epinephrine, moderate reverse Trendelenburg (head-up) positioning, and
volatile anesthetics to decrease arterial blood pressure (within an acceptable
range). The use of potent vasoactive drugs and controlled hypotension is
controversia

Question 70

What is an optimal anesthetic plan for emergence from general anesthesia in the
patient who has undergone middle ear surgery?

Answer 70

The risk of graft disruption or acute hemorrhage is minimized by the smooth
emergence from general anesthesia. Episodic coughing and bucking will produce
hypertension that may result in poor surgical outcome. In the uncomplicated
airway, extubation of the trachea at a deep plane of anesthesia with spontaneous
respiration may be beneficial

Question 71

Why are patients who have undergone middle ear surgery at risk for postoperative
nausea and vomiting?

Answer 71

Postoperative nausea and vomiting is common after middle ear surgery because
of manipulation of the vestibular apparatus. Factors that contribute to PONV include anesthesia technique (use of nitrous oxide and narcotics), inadequate
hydration, and postoperative movement.

Question 72

What anesthetic strategies minimize postoperative nausea and vomiting after ear surgery?

Answer 72

The number of agents used to prevent PONV after ear surgery is guided by a
relative risk analysis. Prophylactic agents include corticosteroids, 5HT3-receptor
antagonists, neurokinin-1 receptor antagonists, scopolamine patches, and
low-dose propofol. Gastric decompression is useful if blood has been swallowed.
Scopolamine crosses the blood-brain barrier and may cause confusion,
particularly in the elderly.

Question 73

What factors contribute to airway obstruction in children undergoing
tonsillectomy and adenoidectomy?

Answer 73

Children undergoing tonsillectomy and adenoidectomy have upper airway
obstruction that often only manifests during sleep. The routine use of premedication
is controversial. Furthermore, airway obstruction is accelerated by large masses
of tonsillar or adenoidal tissue, and loss of pharyngeal tone associated with the
induction of anesthesia. Also, manipulation of the airway during light planes
of anesthesia may result in acute airway obstruction

Question 74

What is negative pressure pulmonary edema?

Answer 74

Negative pressure pulmonary edema clinically manifests when the patient inhales forcefully against a closed glottis. This effort generates marked negative
intrathoracic pressures that are transmitted to the pulmonary interstitial tissue, and promotes fluid transition from the pulmonary circulation into the alveoli.

Question 75

Why is blood loss often underestimated during and after tonsillectomy and
adenoidectomy?

Answer 75

. Blood loss during tonsillectomy and adenoidectomy is either overt (into the
suction bottle) or covert (swallowed). Blood loss is underestimated because the
covert loss is not seen. (

Question 76

What are some considerations for the anesthetic management of patients who
return to surgery because of significant bleeding after tonsillectomy and
adenoidectomy?

Answer 76

Anesthesia considerations for the post-tonsillectomy bleed include the possibility of undetected and prolonged hemorrhage, concomitant hypovolemia, and regurgitation of blood swallowed into the stomach. Measures required include
rehydration, rapid sequence induction of general anesthesia, protection of the
airway with a cuffed endotracheal tube (minimize risk of aspiration), and drainage
of gastric contents

Question 77

77. What organism is frequently responsible for acute epiglottitis?

Answer 77

Acute epiglottitis is an infectious disease caused by Haemophilus influenzae type B.
It most often affects children between the ages of 2 and 7.

Question 78

80. What are the clinical features of foreign body aspiration into the airway?

Answer 78

Tracheal aspiration of a foreign body is an airway emergency. Clinical features
include sudden dyspnea, dry cough, hoarseness, and wheezing.

Question 79

What anesthetic precautions are necessary in acute epiglottitis management?

Answer 79

79. Acute epiglottitis is an airway emergency. Direct visualization of the glottis should not be attempted because stimulation and struggling may produce acute airway obstruction. Emergency airway equipment should be readied. A surgeon adept at rigid bronchoscopy and tracheostomy should be present at the bedside.
    An inhaled induction of anesthesia maintaining spontaneous respiration is
    preferred. Atropine may dry secretions and prevent bradycardia

Question 80

2

Question 81

What anesthesia precautions are necessary in addressing the patient with an airway foreign body?

Answer 81

A preoperative plan and mutual intraoperative cooperation between the anesthesia provider and surgeon are vital in order to avoid inadvertent distal displacement of the foreign body. Removal of the foreign body can be accomplished by either direct laryngoscopy or rigid bronchoscopy. The surgeon should be prepared for an emergency cricothyrotomy or tracheostomy in the event of acute airway occlusion. Total intravenous anesthesia with maintenance of spontaneous ventilation can eliminate operating room pollution

Question 82

What postoperative measures are necessary after the removal of a foreign body from the airway?

Answer 82

After the removal of a foreign body, postoperatively the patient should receive
humidified oxygen and remain under close observation for development of airway
edema

Question 83

What are the disadvantages of using cocaine? Are there alternatives?

Answer 83

Cocaine is an effective topical anesthetic agent. Since it is also a potent vasoconstrictor,
it reduces bleeding in the surgical field and shrinks the nasal mucosa

Question 84

84. What are the disadvantages of using cocaine? Are there alternatives?

Answer 84

The disadvantages of cocaine include altered sensorium (euphoria and dysphoria) and untoward cardiac arrhythmias. For these reasons, cocaine has been surpassed by the “pseudo-cocaine” solution containing a local anesthetic and vasoconstrictor.

Question 85

What considerations are important for general anesthesia emergence in nasal and
sinus surgery?

Answer 85

The removal of posterior pharyngeal packs should be confirmed. Protective airway
reflexes should be present prior to extubation because of possible airway edema and
ongoing bleeding.

Question 86

What preoperative investigations may be useful in a patient undergoing endoscopic
surgery?

Answer 86

Bronchoscopy, laryngoscopy, and microlaryngoscopy involve direct manipulation
of the airway. In these procedures, the airway should be assessed carefully
paying special attention to the presence of stridor (indicator of compromise).
Preoperative investigations such as blood gas analysis, flow-volume loops,
radiographic studies, and magnetic resonance imaging may be useful

Question 87

87. What techniques may be used to maintain ventilation and oxygenation during airway endoscopy?

Answer 87

A variety of techniques can be employed to provide oxygenation and ventilation
during endoscopy. The trachea may be intubated with a small diameter pediatric
endotracheal tube but this may impair visualization of the posterior commissure. An alternative technique, jet ventilation, utilizes high-flow oxygen insufflation
through a small-gauge catheter placed in the trachea

Question 88

What risk is associated with the use of a manual high-pressure jet ventilator
(Sanders’ injector apparatus)?

Answer 88

The use of the manual high-pressure jet ventilator carries risks of pneumothorax
and pneumomediastinum

Question 89

What is a laser? What advantages does it offer for surgical procedures?

Answer 89

Laser is an acronym for light amplification by stimulated emission of radiation.
It produces an intense focused light beam that allows for precise and controlled
coagulation, incision, and vaporization of tissues. Advantages of laser include
its ability to target difficult-to-reach lesions, provide hemostasis, produce minimal
edema, and promote rapid healing

Question 90

90. Name some hazards that are associated with laser surgery.

Answer 90

Hazards associated with laser surgery include atmospheric contamination by fine
particles of vaporized tissues, misdirected laser energy, venous gas embolism,
and ocular (retina) injury. There is also risk of endotracheal tube (ETT) fire during
airway surgery

Question 91

What is the purpose of a smoke evacuator used during laser surgery?

Answer 91

During laser surgery an efficient smoke evacuator, as well as special masks, is
necessary because small, vaporized particles are easily inhaled.

Question 92

What measures can be taken during laser surgery to minimize the risk of an
endotracheal tube fire?

Answer 92

Preoperative:
a. Arrange surgical drapes to avoid accumulation of combustible gases
b. Use appropriate laser-resistant ETT
c. Moisten gauze and sponges in the vicinity of the laser
Intraoperative:
a. Alert surgeon and OR personnel to risk
b. Assign specific roles to each OR member in case of fire
c. Reduce inspired O2 to minimal values
d. Replace N2O with air
e. Wait a few minutes after changes in gas concentration before activating laser

Question 93

93. Why should the ETT cuff be filled with saline or an indicator dye during laser surgery?

Answer 93

The purpose of filling the ETT cuff with saline or an indicator dye during laser
surgery is to help dissipate laser heat. Furthermore, leaking dye is an indicator of
cuff rupture.

Question 94

What medical issues are frequently encountered in patients undergoing radical neck dissection?

Answer 94

Radical neck dissection is indicated for removal of a malignancy. These
patients frequently have a history of tobacco and alcohol abuse. An extensive
preoperative work-up is necessary because pulmonary and cardiac disease is
prevalent. (

Question 95

How does a history of radiation to the larynx, pharynx, or oral cavity affect
anesthetic management?

Answer 95

A history of prior radiation therapy to the larynx, pharynx, or oral cavity may
produce marked tissue indurations, scarring, and limitation of mobility. These
may cause difficulties with airway management, particularly endotracheal
intubation.

Question 96

What arrhythmias may be precipitated during radical neck dissection, and why?

Answer 96

Traction or pressure on the carotid sinus may provoke acute arrhythmias.
These include prolongation of the QT interval, bradydysrhythmias, and asystole.
Treatment includes early detection, cessation of the surgical stimulus, and
administration of an anticholinergic agent. Another option is local anesthetic
infiltration of the carotid sinus.

Question 97

What known injuries may be encountered postoperatively after radical neck
dissection?

Answer 97

Injuries to the facial (VII) nerve, recurrent laryngeal nerve, and phrenic nerve may
all be encountered postoperatively after radical neck dissection surgery

Question 98

What catastrophic postoperative event may occur after neck surgery?

Answer 98

Hematoma formation in the neck may compress the airway leading to acute
obstruction. If tracheotomy is not performed during the initial surgery, then the
patient requires close monitoring (for laryngeal or upper airway obstruction)
in the postoperative phase.

Question 99

How may hypocalcemia present after thyroid surgery?

Answer 99

Hypocalcemia after thyroid surgery may present in many forms. Clinical signs may
include tetany (carpal spasm), peripheral and circumoral paresthesia, QT
interval prolongation, and laryngospasm

Question 100

The patient is unable to grimace after a parotidectomy. Why? What monitor(s)
may help prevent this complication?

Answer 100

The inability to perform a symmetrical grimace after parotid surgery is indicative
of facial nerve injury or traction. Since the parotid gland is traversed by the
facial nerve, it is customary to monitor the facial nerve function with a facial nerve
monitor. Occasionally, the facial nerve may need to be sacrificed. It is then
reconstructed with a graft from the greater auricular nerve.