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Medical Emergencies · patient case with 6 questions

Medical Emergency in the Operatory

demo: 34-year-old female

chief: Composite restoration on tooth #3 under rubber dam isolation.

history: Asthma, well controlled. No known drug allergies. Latex sensitivity not previously documented.

meds: Albuterol inhaler as needed

findings: Ten minutes after rubber dam placement the patient develops audible wheezing, swelling of the lips and periorbital tissue, and urticaria over the neck.

Question 1

What is the most appropriate immediate drug intervention?

  1. Diphenhydramine 50 mg orally
  2. Hydrocortisone 100 mg intravenously
  3. Epinephrine 1:1000, 0.3 mg intramuscularly
  4. Albuterol inhaler, 2 puffs
Show answer and explanation

Correct answer: C. Epinephrine 1:1000, 0.3 mg intramuscularly

  • A. Antihistamines are adjunctive and far too slow for airway compromise; they treat the cutaneous signs only.
  • B. Corticosteroids blunt the late-phase reaction but have no useful onset in the first minutes.
  • C. Correct. Wheezing plus angioedema and urticaria is anaphylaxis. Intramuscular epinephrine 1:1000 is the first-line drug — remove the dam, position the patient, give oxygen, and activate EMS.
  • D. Albuterol addresses bronchospasm but does nothing for the angioedema or the circulatory component.

Note: Sequence matters: remove the allergen, epinephrine first, then oxygen, call 911, and give antihistamine and corticosteroid as secondary agents.

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Question 2

The concentration 1:1000 corresponds to which amount of epinephrine per milliliter?

  1. 1 mg/mL
  2. 0.1 mg/mL
  3. 10 mg/mL
  4. 0.01 mg/mL
Show answer and explanation

Correct answer: A. 1 mg/mL

  • A. Correct. A 1:1000 dilution is 1 gram in 1000 mL, which is 1 mg per mL — the intramuscular anaphylaxis concentration.
  • B. 0.1 mg/mL is 1:10,000, the intravenous concentration used in cardiac arrest.
  • C. 10 mg/mL would be 1:100, which is not a clinical preparation for this use.
  • D. 0.01 mg/mL is 1:100,000, the concentration of epinephrine in local anesthetic cartridges.

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Question 3

A different patient with an unrepaired congenital heart murmur presents for scaling. What antibiotic prophylaxis is indicated?

  1. None — an isolated unrepaired murmur is not a qualifying condition
  2. Azithromycin 500 mg one hour before
  3. Clindamycin 600 mg one hour before
  4. Amoxicillin 2 g one hour before
Show answer and explanation

Correct answer: A. None — an isolated unrepaired murmur is not a qualifying condition

  • A. Correct. Current AHA guidance limits prophylaxis to prosthetic valves or material, previous infective endocarditis, certain unrepaired or incompletely repaired cyanotic congenital heart disease, and cardiac transplant valvulopathy. A murmur alone does not qualify.
  • B. Azithromycin is an alternative agent, but the premise — that prophylaxis is needed — is wrong.
  • C. Clindamycin is a penicillin-allergy alternative, again only when prophylaxis is warranted.
  • D. Amoxicillin is the correct drug when prophylaxis is indicated, but here it is not indicated.

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Question 4

A patient in myxedema coma would display all of the following EXCEPT:

  1. Bradycardia
  2. Tachycardia
  3. Depressed mental status
  4. Hypothermia
Show answer and explanation

Correct answer: B. Tachycardia

  • A. Bradycardia is characteristic and reflects the low metabolic state.
  • B. Correct — this is the exception. Myxedema coma is decompensated hypothyroidism; the metabolic rate collapses, so the heart rate falls. Tachycardia would suggest thyroid storm, the opposite emergency.
  • C. Altered consciousness ranging from lethargy to coma defines the syndrome.
  • D. Hypothermia is one of the cardinal features and may be profound.

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Question 5

A patient with type 1 diabetes mellitus would exhibit all of the following EXCEPT:

  1. Risk of diabetic ketoacidosis
  2. Autoimmune destruction of pancreatic beta cells
  3. Absolute insulin deficiency
  4. Insulin resistance
Show answer and explanation

Correct answer: D. Insulin resistance

  • A. DKA is far more characteristic of type 1 than of type 2 because of the complete absence of insulin.
  • B. Type 1 is autoimmune, with islet cell and GAD antibodies commonly detectable.
  • C. Absolute deficiency from beta cell loss is the defining lesion of type 1.
  • D. Correct — this is the exception. Insulin resistance is the hallmark of type 2 diabetes. Type 1 patients are typically insulin sensitive; their problem is that there is no insulin to respond to.

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Question 6

Lithium toxicity in a patient on long-term therapy most characteristically produces:

  1. Hepatic cirrhosis
  2. Renal impairment, including nephrogenic diabetes insipidus and chronic kidney injury
  3. Pulmonary fibrosis
  4. Aplastic anemia
Show answer and explanation

Correct answer: B. Renal impairment, including nephrogenic diabetes insipidus and chronic kidney injury

  • A. Hepatic cirrhosis is not a lithium effect; lithium undergoes no hepatic metabolism.
  • B. Correct. Lithium is cleared entirely by the kidney and is nephrotoxic; chronic use causes nephrogenic diabetes insipidus and progressive renal impairment, alongside tremor and thyroid effects. NSAIDs raise lithium levels, which matters for dental analgesia.
  • C. Pulmonary fibrosis is associated with amiodarone, bleomycin, and methotrexate.
  • D. Aplastic anemia is associated with chloramphenicol and carbamazepine, not lithium — lithium actually raises the white count.

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