A client returns to the cardiovascular intensive care unit following his coronary artery bypass graft. In planning his care, the most important electrolyte the nurse needs to monitor will be?

1. A

   Chloride

2. B

   HCO₃

3. C

   Potassium

4. D

   Sodium

Appeared in: NORCET 6 mains-2024

Explanation

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• Potassium is the primary intracellular cation and is critical for regulating nerve impulse transmission, muscle contraction, and most importantly, the heart's pacemaker function and rhythm.
• Post-CABG patients are highly susceptible to potassium imbalances due to factors like cardiopulmonary bypass, diuretic use, and the physiological stress of surgery.
• Both hypokalemia (serum potassium less than 3.5 mEq/L) and hyperkalemia (serum potassium greater than 5.0 mEq/L) can precipitate life-threatening cardiac dysrhythmias, including ventricular fibrillation and cardiac arrest.
• Given the immediate risk of fatal arrhythmias in a post-cardiac surgery patient, maintaining potassium within its narrow therapeutic range is the highest priority.

Why Other Options Were Wrong

• Option A: Chloride is an anion that works with sodium to maintain fluid and acid-base balance. While important, its fluctuations do not pose the same immediate, life-threatening risk to cardiac electrical stability as potassium.
• Option B: Bicarbonate (HCO3) is the primary metabolic buffer in the body, crucial for maintaining blood pH. While metabolic acidosis is a concern after CABG, managing it does not take precedence over preventing an imminent cardiac arrest from a potassium imbalance.
• Option D: Sodium is the primary extracellular cation and is vital for maintaining fluid balance and neurological function. While sodium imbalances can lead to serious issues like seizures or cerebral edema, they do not have the direct, potent, and immediate effect on cardiac rhythm that potassium does.

Related Visual

Clinical Relevance

• Nursing practice connection: Use the key finding related to Priority electrolyte monitoring post-coronary artery bypass graft (CABG) surgery to guide bedside assessment, documentation, and the next nursing action.
• In the CVICU, nurses are responsible for continuous cardiac monitoring and frequent lab draws to track potassium levels in post-CABG patients.
• A critical nursing safety intervention is the careful administration of intravenous potassium. It must always be diluted and infused via a pump at a controlled rate (e.g., no faster than 10 mEq/hr on an unmonitored unit) to prevent iatrogenic hyperkalemia and cardiac arrest.
• What if? If the post-CABG patient's monitor suddenly shows tall, peaked T-waves, the nurse must recognize this as a sign of hyperkalemia, immediately stop any potassium infusions, notify the provider, and prepare to administer emergency interventions like IV insulin and dextrose to rapidly shift potassium into the cells.

How to Approach the Question

• First, analyze the clinical scenario: The patient is in a critical care setting (CVICU) immediately after major heart surgery (CABG). This context highlights that cardiac function is the primary concern.
• Next, identify the core of the question: It asks for the 'most important' electrolyte to monitor. This is a prioritization question, requiring you to determine the most immediate life-threatening risk.
• Evaluate the options based on their physiological roles. Consider which electrolyte has the most direct and significant impact on cardiac muscle function and electrical conduction.
• Recall the functions: Sodium affects fluid/neuro, Chloride affects fluid/acid-base, Bicarbonate affects acid-base, and Potassium directly affects cardiac rhythm.
• Connect the highest risk (cardiac arrhythmia) with the electrolyte that most directly influences it. Potassium imbalances are a well-known cause of fatal arrhythmias.
• Therefore, conclude that monitoring potassium is the highest priority to ensure patient safety in this specific clinical context.

Concept Tested & Keywords

• Concept Tested: Priority electrolyte monitoring post-coronary artery bypass graft (CABG) surgery.
• Stem keywords: coronary artery bypass graft, CABG, cardiovascular intensive care unit, electrolyte, monitor
• Lead-in keywords: most important
• Clinical cues: The patient is in the cardiovascular ICU immediately following CABG, indicating a high-acuity situation where cardiac stability is the top priority.
• Negative lead-in flag: false

Question ID

Q13WCy0LlOZO_P_wL3kqiQ

Copy ID

Reference Book

E6 Pharmacology Nursing Lilley 11e Part 2 pp. 164-166, 172-174, 169-171