Dental MCQ
pH homeostasis · Biochemistry · INBDE Patient Cases

Acid-Base Balance INBDE Patient Cases

By Dr. Isaac Sun, DDS

4 ADA INBDE-format patient cases on acid-base balance. Each case is a shared patient box (chief complaint, history, medications, allergies, exam) followed by linked multiple-choice questions with full distractor explanations. Practice the way the real exam is structured.

4 patient cases20 linked questionsADA INBDE formatFull distractor explanations

Four ADA INBDE-format patient cases connecting acid-base balance to dentistry: anxiety hyperventilation causing respiratory alkalosis with perioral tingling (managed by slow breathing, not oxygen), opioid over-sedation causing respiratory acidosis reversed by naloxone, a COPD patient with chronic compensated respiratory acidosis and sedation and oxygen caution, and salicylate (aspirin) overdose with a mixed respiratory alkalosis and high anion gap metabolic acidosis. Topics include the Henderson-Hasselbalch relationship, the bicarbonate buffer, respiratory and metabolic acidosis and alkalosis, the anion gap, and compensation.

Case Coverage Map
What each case is testing
Tingling and lightheaded from anxious breathing:
Respiratory alkalosis from hyperventilation, the low ionized calcium causing tingling, slow-breathing management, and why oxygen is not the answer.
Too sleepy and breathing slowly after sedation:
Opioid respiratory depression and respiratory acidosis, the pinpoint-pupil triad, naloxone, and airway and ventilatory support.
A COPD patient considering sedation:
Chronic respiratory acidosis with renal compensation, sedation risk, controlled oxygen, and minimizing respiratory depressants.
Took too much aspirin for a toothache:
Salicylate toxicity, the mixed respiratory alkalosis and high anion gap acidosis, tinnitus, and counseling safe analgesia.
Patient case: Tingling and lightheaded from anxious breathing
0 of 5 answered, 0 correct
Patient
Female, 26 years old
Chief Complaint
"My lips and fingers are tingling and I feel dizzy."
Background and/or Patient History
  • Very anxious about the dental visit
  • Began breathing rapidly and deeply before the injection
  • Now reports perioral and finger tingling and lightheadedness
  • No chest pain, no wheeze, no history of lung disease
Allergies
NKDA
Medications
  • None
Current Findings
  • Rapid, deep breathing
  • Perioral and finger tingling, early hand cramping
  • Oxygen saturation normal
  1. Question 1
    Moderate
    Her rapid breathing with tingling and lightheadedness is most likely causing:
  2. Question 2
    Hard
    Her tingling and hand cramping occur because the alkalosis:
  3. Question 3
    Moderate
    The most appropriate management is to:
  4. Question 4
    Moderate
    Why is supplemental oxygen NOT the answer here?
  5. Question 5
    Moderate
    Which feature would instead point to a true hypoxic emergency (such as an asthma attack) needing oxygen?

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Patient case: Too sleepy and breathing slowly after sedation
0 of 5 answered, 0 correct
Patient
Male, 60 years old
Chief Complaint
Reported by staff: "He's very drowsy and barely breathing after his sedation and pain medicine."
Background and/or Patient History
  • Received an opioid for sedation and post-operative pain
  • Became progressively more somnolent
  • Slow, shallow breathing noted
  • Difficult to rouse
Allergies
NKDA
Medications
  • Opioid (recently given)
Current Findings
  • Slow, shallow respirations
  • Pinpoint pupils
  • Falling oxygen saturation, hard to arouse
  1. Question 1
    Moderate
    His somnolence with slow, shallow breathing and pinpoint pupils points to:
  2. Question 2
    Moderate
    His acid-base disturbance is a:
  3. Question 3
    Moderate
    The specific reversal agent for opioid respiratory depression is:
  4. Question 4
    Moderate
    The immediate priorities while preparing the antidote are to:
  5. Question 5
    Moderate
    This case is a reminder to prescribe and administer opioids:

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Patient case: A COPD patient considering sedation
0 of 5 answered, 0 correct
Patient
Male, 68 years old
Chief Complaint
"I have bad emphysema and I'm nervous about getting this tooth out."
Background and/or Patient History
  • Long-standing COPD (emphysema), uses inhalers
  • Considering sedation for an extraction
  • Gets short of breath with exertion
  • A recent panel showed a chronically high bicarbonate
Allergies
NKDA
Medications
  • Bronchodilator inhalers
Current Findings
  • Mild baseline shortness of breath
  • Prolonged expiration
  • Chronically elevated bicarbonate on labs
  1. Question 1
    Hard
    His baseline acid-base state from chronic CO2 retention is best described as:
  2. Question 2
    Moderate
    His chronically high bicarbonate is explained by:
  3. Question 3
    Moderate
    The main risk of using sedatives or opioids in him is:
  4. Question 4
    Moderate
    A reasonable approach to his care is to:
  5. Question 5
    Hard
    Regarding supplemental oxygen in a CO2-retaining COPD patient, the best principle is to:

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Patient case: Took too much aspirin for a toothache
0 of 5 answered, 0 correct
Patient
Female, 35 years old
Chief Complaint
"I took a lot of aspirin for my tooth pain and now my ears are ringing."
Background and/or Patient History
  • Severe toothache for two days, self-treated with repeated high doses of aspirin
  • Now reports ringing in the ears and nausea
  • Breathing rapidly
  • Has not seen a physician
Allergies
NKDA
Medications
  • Aspirin (excessive self-dosing)
Current Findings
  • Tachypnea (rapid breathing)
  • Reports tinnitus and nausea
  • Appears unwell
  1. Question 1
    Moderate
    Her tinnitus, nausea, and rapid breathing after heavy aspirin use suggest:
  2. Question 2
    Hard
    The classic acid-base picture of salicylate overdose is:
  3. Question 3
    Moderate
    Her rapid breathing is largely because salicylates:
  4. Question 4
    Moderate
    The most appropriate action is to:
  5. Question 5
    Moderate
    The broader lesson for dental pain management is to:

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Keep studying
Acid-Base Balance core recall

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