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RUHS, Jaipur, M.Sc Nursing Entrance Exam-2016
Medical Surgical Nursing
Easy

ECG changes seen in hypocalcaemia are?

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2016

Explanation

  • Hypocalcemia characteristically causes a prolonged QT interval on an ECG.
  • This occurs because low extracellular calcium prolongs the plateau phase (Phase 2) of the cardiac action potential.
  • The prolongation of the plateau phase manifests as a lengthening of the ST segment, which in turn increases the total duration of the QT interval.
  • This ECG change indicates an increased risk for dangerous ventricular arrhythmias, such as Torsades de Pointes.

Why Other Options Were Wrong

  • Option A: While conceptually similar to a prolonged QT interval, 'prolonged' is the standard and more precise medical term used to describe an increase in the time duration of an ECG interval.
  • Option B: A prominent U wave is a classic ECG finding associated with hypokalemia (low potassium levels), not hypocalcemia.
  • Option C: A widened T wave is not a characteristic finding of hypocalcemia. T-wave abnormalities are more commonly associated with potassium imbalances, such as the tall, peaked T waves seen in hyperkalemia.

Related Visual

Visual explanation — Related Visual
Clinical Relevance
  • Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain ECG Interpretation in Electrolyte Imbalances as background academic context rather than a clinical decision trigger.
  • Nurses must be able to recognize a prolonged QT interval in patients at risk for hypocalcemia (e.g., post-thyroidectomy, pancreatitis, renal failure) as it signals an increased risk for life-threatening arrhythmias like Torsades de Pointes.
  • Promptly reporting this finding to the physician is a critical patient safety intervention that can lead to timely calcium replacement therapy.
  • What if the patient's ECG showed a shortened QT interval? The nurse should suspect the opposite condition, hypercalcemia, and anticipate orders for a serum calcium level check and interventions to lower calcium.
How to Approach the Question
  • First, identify the core of the question: it asks for the specific ECG change related to hypocalcemia.
  • Access your knowledge base on how common electrolyte imbalances affect the ECG.
  • Evaluate each option. Recall or deduce that a prolonged QT interval is the textbook answer for hypocalcemia.
  • Eliminate the other options by correctly associating them with different conditions: a 'prominent U wave' is linked to hypokalemia, and significant T-wave changes are most often related to potassium imbalances.
  • Differentiate between 'widened QT interval' and 'prolonged QT interval'. Recognize that 'prolonged' is the standard medical term for an interval's time duration, making it the more precise and correct choice.
Concept Tested & Keywords
  • Concept Tested: ECG Interpretation in Electrolyte Imbalances
  • Stem keywords: ECG changes, hypocalcaemia
  • Lead-in keywords: are
  • Negative lead-in flag: false

Question ID

Q2IecsSK7GkqDk7th1ZaR0

Reference Book

E6 Medicine Harrison 22e Part 1 pp. 1916-1918, 1911-1913

E6 Robert Boland, Marcia L. Verduin - Kaplan and Sadock's Comprehensive Text of Psychiatry-Wolters Kluwer Health (2024) (pp 1-16525 of 16525) p. 7320-7322

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