While checking the blood pressure in the upper limb of a patient with a sphygmomanometer, you observe that she has developed carpal spasm. The most likely cause is:

Appeared in: GMCH - 2016

Explanation

The scenario describes Trousseau's sign, which is a carpal spasm induced by occluding blood flow to the arm, typically with a blood pressure cuff.
Trousseau's sign is a classic clinical finding for hypocalcemia (low serum calcium).
Hypocalcemia leads to increased neuromuscular excitability, causing involuntary muscle contractions (tetany) when a nerve is irritated or made ischemic.
The inflation of the sphygmomanometer cuff causes temporary ischemia, which triggers the latent tetany in a patient with hypocalcemia.

Option A: Hypokalemia (low potassium) primarily causes muscle weakness, fatigue, paralysis, and cardiac arrhythmias. It does not typically cause tetany or carpal spasms.
Option B: Hyponatremia (low sodium) mainly affects the central nervous system, leading to symptoms like confusion, headache, nausea, and in severe cases, seizures and coma due to cerebral edema. It does not cause carpal spasm.
Option D: While severe hyperphosphatemia (high phosphate) can cause hypocalcemia (due to the inverse relationship between calcium and phosphate), the direct cause of the tetany and carpal spasm is the resulting low calcium level, not the high phosphate level itself. Therefore, hypocalcemia is the more direct and precise answer.

Clinical Relevance

Nursing practice connection: Use the key finding related to Recognition of clinical signs associated with electrolyte imbalances to guide bedside assessment, documentation, and the next nursing action.
Recognizing Trousseau's sign is a critical nursing skill, as it indicates latent tetany and a risk for more severe complications like laryngospasm or seizures.
Nurses should be vigilant for signs of hypocalcemia in at-risk patients, such as those who have undergone thyroid or parathyroid surgery, patients with pancreatitis, chronic kidney disease, or vitamin D deficiency.
If Trousseau's sign is observed, the nurse should immediately stop the BP measurement, ensure patient safety, notify the healthcare provider, and anticipate orders for a stat serum calcium level and possible IV calcium gluconate administration.

How to Approach the Question

First, identify the key action and patient response in the question: inflating a blood pressure cuff leads to carpal spasm.
Recognize this specific clinical presentation as a named sign. This is Trousseau's sign.
Recall the pathophysiology associated with Trousseau's sign. It is a sign of latent tetany caused by increased neuromuscular excitability.
Link the underlying cause of this increased excitability to a specific electrolyte imbalance. Trousseau's sign is a classic indicator of hypocalcemia.
Review the options provided and select the one that matches your conclusion.
Eliminate other options by recalling their primary manifestations (e.g., hypokalemia causes weakness, hyponatremia causes CNS changes).

Concept Tested & Keywords

Concept Tested: Recognition of clinical signs associated with electrolyte imbalances.
Stem keywords: blood pressure, sphygmomanometer, carpal spasm
Lead-in keywords: most likely cause
Clinical cues: The development of carpal spasm during BP measurement is a specific clinical sign (Trousseau's sign).

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Practise the full GMCH - 2016

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