PHARMACOLOGY,
PATHOPHYSIOLOGY, AND
PHYSICAL ASSESSMENT
ADVANCED CLINICAL
JUDGMENT
SIMULATION
QUESTION 1
A patient with systolic heart failure is prescribed Enalapril. During the physical
assessment, the nurse notes bilateral crackles in the lung bases, a third heart sound (S3),
and jugular venous distention. The provider also reviews the morning labs and notes a
serum potassium level of 6.2 mEq/L. What is the primary pathophysiologic rationale for
the hyperkalemia, and what is the priority nursing action regarding the Enalapril?
A. The heart failure causes metabolic acidosis, which shifts potassium out of the
cells; hold the Enalapril and notify the provider.
B. Enalapril blocks the conversion of Angiotensin I to Angiotensin II, which
prevents the secretion of aldosterone, leading to potassium retention; hold the Enalapril
and notify the provider.
C. Enalapril directly stimulates the distal tubules to reabsorb potassium; administer
a loop diuretic and continue the Enalapril.
D. The bilateral crackles indicate hypoxia, which causes cellular destruction and
release of intracellular potassium; hold the Enalapril and administer calcium gluconate.
ANSWER: B
, RATIONALE: This question integrates cardiac pathophysiology, assessment, and
pharmacology. The assessment findings (crackles, S3, JVD) confirm volume overload
due to heart failure. Pharmacologically, ACE inhibitors like Enalapril block the
reninangiotensin-aldosterone system (RAAS). By blocking Angiotensin II, the adrenal
glands are not stimulated to release aldosterone. Aldosterone normally reabsorbs
sodium in exchange for secreting potassium into the urine. Without aldosterone,
potassium is retained. A level of 6.2 mEq/L is dangerously high and requires holding
the medication to prevent life-threatening dysrhythmias.
QUESTION 2
A patient with a 40-year history of heavy smoking presents with a barrel chest, using
accessory muscles to breathe, and pursed-lip exhalation. The physical assessment
reveals diminished breath sounds and a prolonged expiratory phase. The patient's
arterial blood gas (ABG) shows a PaO2 of 52 mmHg and a PaCO2 of 60 mmHg. The
provider orders 2 liters of oxygen via nasal cannula. Why is it contraindicated to
administer high-flow oxygen (e.g., 10 liters via non-rebreather) to this specific patient?
A. High-flow oxygen will cause severe vasoconstriction in the pulmonary
vasculature, increasing right heart strain.
B. The patient has lost the chemical drive to breathe due to chronic CO2 retention;
high-flow oxygen removes the hypoxic drive, leading to respiratory failure.
C. High-flow oxygen dries out the airways, causing thick mucus plugs that will
completely obstruct the already narrowed airways.
D. The patient's prolonged expiratory phase indicates air trapping; adding high-flow
oxygen will increase the rate of gas absorption in the bullae, causing pneumothorax.
ANSWER: B
RATIONALE: This integrates respiratory pathophysiology, assessment, and oxygen
pharmacology. The barrel chest, pursed-lip breathing, and prolonged expiratory
phase are classic assessment findings for COPD (specifically emphysema). The ABG
shows chronic hypercapnia (high CO2). In healthy individuals, high CO2 drives
respiration. In chronic CO2 retainers, the central chemoreceptors become blunted to
high CO2. The body switches to relying on low oxygen levels (PaO2) in the peripheral
chemoreceptors as the primary drive to breathe. Giving high-flow oxygen removes this
hypoxic stimulus, causing the patient to stop breathing effectively, worsening the
hypercapnia and causing acute respiratory acidosis.