General oto critical care

Question 1

Describe the mechanism of malignant hyper-

thermia.

Answer 1

It is caused by a combination of a volatile inhalational
anesthetic (commonly halothane) and the short-acting
paralytic succinylcholine. An abnormal ryanodine receptor
causes overwhelming amounts of calcium to be released
from the sarcoplasmic reticulum of skeletal muscle, thereby
initiating prolonged and intense muscle contraction.

Question 2

What is the initial treatment for malignant hyper-

thermia?

Answer 2

Stop the anesthetic, give dantrolene (which prevents the
release of calcium from endoplasmic reticulum), increase
oxygen, and initiate cooling measures including ice packs.

Question 3

What are the physical examination findings of

cardiac tamponade?

Answer 3

Tachycardia, paradoxical pulse with respirations, hypoten-

sion, jugular vein distension, muffled cardiac sounds, decreased QRS amplitude on electrocardiogram (ECG)

Question 4

What is the formula describing the rate of fluid

maintenance for the pediatric patient?

Answer 4

The 4:2:1 rule = 4 mL/kg hourly for the first 10 kg, adding 2
mL/kg per hour for the second 10 kg, and adding 1 mL/kg
per hour for each kilogram over 20 kg

Question 5

What is the formula used to calculate the rate of

fluid resuscitation of a burn victim?

Answer 5

The Parkland formula: Fluid for the first 24 hours (milli-
liter) = 4 x patient weight (kg) x % body surface area involved; the first half is given over 8 hours, the second half
over the remaining 16 hours. Rule of 9’s for determining
percentage of burned: 9% = head, each arm; 18% = chest,
back, each leg

Question 6

What preoperative condition is associated with immunosuppression, poor wound healing, de-
creased basal metabolic rate, longer hospitaliza-
tion, and an increased mortality rate?

Answer 6

Preoperative malnutrition

Question 7

Why should gastric residuals be checked every 4
hours in a patient receiving enteral nutrition via
tube feeds?

Answer 7

Regurgitation and aspiration are risks of tube feeding

Question 8

What is involved in the refeeding syndrome that is observed in severely malnourished patients fol-
lowing initiation of feeds?

Answer 8

Malnourishment leads to hypoinsulinemia and electrolyte
abnormalities including intracellular hypophosphatemia.
Within 4 to 5 days of reinitiation of carbohydrate
metabolism and subsequently increased insulin production,
patients can develop severe hypophosphatemia.

Question 9

You are rounding on a patient who underwent
major surgery for polytrauma and required 20
units of packed red blood cells. The patient is
complaining of perioral numbness and tingling.
What is the likely diagnosis and treatment?

Answer 9

Citrate toxicity with subsequent hypocalcemia. Treat with
calcium gluconate. This should be given for symptomatic
patients only.

Question 10

What medications can be given as pretreatment to
prevent mild hypersensitivity and nonhemolytic
febrile reactions in a patient receiving blood
transfusion with a history of mild reactions?

Answer 10

Acetaminophen and antihistamines such as diphenhy-

dramine

Question 11

What complications may be encountered in a
patient who has received massive intraoperative
transfusions?

Answer 11

Volume overload, hyperplasia or hypokalemia, hyperam-
monemia, acidosis, thrombocytopenia, coagulation factor
depletion, coagulopathy, hypothermia, transfusion related
acute lung injury, and citrate toxicity

Question 12

What is transfusion-related acute lung injury?

Answer 12

Acute respiratory distress and noncardiogenic pulmonary
edema that develops during or within 6 hours of blood
transfusion. Treatment includes supportive measures, often
including mechanical ventilation, high-inspired oxygen, and
positive end expiratory pressures.

Question 13

Mechanical ventilation is most commonly deliv-
ered via positive-pressure ventilation (PPV). What
are the two most common subtypes of PPV that
focus on the transition from inspiration to expira-
tion?

Answer 13

● Volume control: A set volume is delivered per breath

● Pressure control: A set pressure is delivered per breath

Question 14

What common rule can be used to select the tidal
volume and rate for a patient on assist control
mechanical ventilation?

Answer 14

12–12 rule: 12 mL/kg of lean body mass delivered 12 times
a minute. It is useful for patients without preexisting lung
disease. It must be adjusted for patients with known chronic
obstructive pulmonary disease (COPD), etc.

Question 15

What technique can be used in mechanical
ventilation to maintain a patient’s airway pressure above atmospheric pressure at the end of expira-
tion?

Answer 15

Positive end expiratory pressure (PEEP)

Question 16

What is the difference in the 1-second forced
expiratory volume FEV1 to vital capacity (FVC)
ratio in COPD compared with that in restricted
lung disease?

Answer 16

In COPD, the FEV1/FVC ratio decreases, whereas the ratio is

preserved or increased in restrictive lung disease.

Question 17

Describe the difference between the two types of

postobstructive pulmonary edema.

Answer 17

● Type 1. Follows an acute severe cause of upper airway
obstruction (epiglottitis, laryngospasm, strangulation)
and usually manifests within 1 hour of the event
● Type 2. Follows relief from a chronic obstruction (obstructive sleep apnea (OSA), choanal stenosis, sub-
glottic stenosis) and usually manifests within 6 hours of reversing the obstruction

Question 18

What is the treatment of postobstructive pulmo-

nary edema?

Answer 18

Oxygen and supportive care in mild cases and PEEP in more
severe cases. Diuretic therapy can be instituted, although
the benefit is not clear.

Question 19

What is the most common cause of fever in the

immediate postoperative period?q

Answer 19

Within the first 48 hours of surgery, fever is likely due to an
inflammatory reaction to surgical insult or reaction to
medication or blood product given intraoperatively. It is
unlikely to be infectious. Evaluate for possible source of
infection, but prophylactic antibiotics are not indicated.
Patient may be treated with antipyretic and monitor for
change in clinical status.

Question 20

In the acute postoperative setting, how can the
mnemonic “Wind, Water, Walk, Wound, Wonder
Drugs, What did you do?” help in the evaluation of
a febrile patient?

Answer 20

● Wind: Pneumonia? Aspiration? Atelectasis?
● Water: Urinary tract infection?
● Walk: Thrombophlebitis? Deep venous thrombosis?
Pulmonary embolus?
● Wound: Surgical-site infection?
● Wonder drugs: Drug reaction (β-lactam antibiotic? Sulfa
antibiotic?)
● What did we do? Catheter-related infection? IV site
infection?