A patient undergoes nasogastric suctioning for several days. Which electrolyte imbalance is most likely to occur due to this treatment?

Appeared in: NORCET 6 Prelims -2024

Explanation

Nasogastric (NG) suction removes gastric fluid, which is rich in potassium (K⁺).
Prolonged removal of this fluid directly depletes the body's potassium stores.
The loss of gastric acid (HCl) also causes metabolic alkalosis.
Metabolic alkalosis further worsens hypokalemia by causing potassium to shift into cells and increasing its excretion by the kidneys.
Therefore, hypokalemia is the most common and significant electrolyte imbalance associated with NG suctioning.

Option A: Hyperkalemia is an elevated potassium level. NG suction causes the loss of potassium, leading to the opposite condition (hypokalemia).
Option B: Hypernatremia (high sodium) is primarily caused by excessive water loss or excessive sodium intake. While fluid balance is a concern with NG suction, hypokalemia is the more direct and likely consequence due to the composition of gastric fluid.
Option D: Hypercalcemia (high calcium) is not related to the loss of gastric fluids. Its causes are linked to bone metabolism and calcium regulation.

Visual 1: Infographic: Signs and symptoms of hypokalemia (e.g., muscle weakness, fatigue, constipation, cardiac arrhythmias, flattened T-waves on ECG).
Visual 2: Diagram: A flowchart illustrating how nasogastric suction leads to hypokalemia and metabolic alkalosis through direct loss and compensatory renal and cellular mechanisms.

Clinical Relevance

Nursing practice connection: Use the key finding related to Electrolyte Imbalances from Gastrointestinal Fluid Loss to guide bedside assessment, documentation, and the next nursing action.
A nurse caring for a patient with an NG tube on suction must prioritize monitoring for signs of hypokalemia, such as muscle weakness, cardiac dysrhythmias, and decreased bowel sounds.
Regularly reviewing serum electrolyte levels (especially potassium, chloride, and magnesium) and arterial blood gases (ABGs) is a critical nursing intervention.
What if the patient was also taking a potassium-wasting diuretic like furosemide? The risk for severe, life-threatening hypokalemia would be dramatically increased, requiring more frequent monitoring and proactive potassium replacement as ordered by the physician.

How to Approach the Question

First, identify the core procedure in the question: 'nasogastric suctioning'.
Recall the physiological function of the stomach and the composition of its secretions. Gastric juice is acidic (HCl) and contains electrolytes, notably potassium (K⁺).
Consider the effect of removing this fluid from the body for 'several days'. This implies a significant and prolonged loss.
Connect the loss of specific components to electrolyte imbalances. Loss of K⁺ leads to hypokalemia. Loss of HCl leads to metabolic alkalosis, which further worsens hypokalemia.
Evaluate the given options based on this physiological reasoning. Hypokalemia is a direct and amplified consequence.
Eliminate other options by considering their typical causes, which do not align with the effects of removing gastric fluid.

Concept Tested & Keywords

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Practise the full NORCET 6 Prelims -2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.