For a mother receiving magnesium sulphate for symptoms of hypomagnesaemia, an important sign for the nurse to… - BCCL kharkhanda Staff Nurse - 2015

BCCL kharkhanda Staff Nurse - 2015

Obstetrics & Gynaecology

Easy

Appeared in: BCCL kharkhanda Staff Nurse - 2015

Explanation

Decreased or absent deep tendon reflexes (DTRs), also known as hyporeflexia, is the earliest and most critical clinical sign of magnesium toxicity.
This sign indicates that serum magnesium levels are rising into the toxic range, typically between 7.0 and 10.0 mg/dL.
It serves as a crucial warning sign that precedes more life-threatening complications, such as respiratory depression (which occurs around 10-12 mg/dL) and cardiac arrest (at levels above 12 mg/dL).
Monitoring the patellar reflex (knee-jerk) is a standard nursing assessment to ensure patient safety during magnesium sulphate therapy.

Option A: Cool skin temperature is a non-specific finding and is not a direct or early indicator of magnesium toxicity.
Option B: A rapid pulse rate (tachycardia) is not a sign of magnesium toxicity. Magnesium is a central nervous system depressant, and toxicity leads to bradycardia (slowed heart rate) and hypotension.
Option C: Tingling in the toes (paresthesia) is a classic symptom of hypomagnesaemia (low magnesium levels), the very condition being treated.

Clinical Relevance

Nursing practice connection: Use the key finding related to Nursing assessment and monitoring for magnesium sulphate toxicity to guide bedside assessment, documentation, and the next nursing action.
Magnesium sulphate is a high-alert medication requiring frequent and diligent monitoring of deep tendon reflexes, respiratory rate (at least every hour), urine output (must be at least 30 mL/hr), and level of consciousness.
The antidote for magnesium toxicity, calcium gluconate (1g IV over 3 minutes), must be readily available at the bedside whenever a patient is receiving a magnesium sulphate infusion.
What if? If the nurse assesses absent DTRs and a respiratory rate of 10 breaths/min, the immediate priority is to stop the magnesium infusion, call for help, notify the healthcare provider, and prepare to administer intravenous calcium gluconate as ordered.

How to Approach the Question

First, identify the core of the question: it asks for the first important sign of a complication related to a specific medication.
Identify the medication: Magnesium Sulphate. Recall its therapeutic use (treating hypomagnesaemia, preventing eclamptic seizures) and its primary adverse effect (magnesium toxicity/hypermagnesaemia).
Recall the progression of signs for magnesium toxicity. This typically follows a sequence: loss of deep tendon reflexes, followed by respiratory depression, and finally cardiac arrest.
Evaluate the options based on this progression. The question asks for the first sign, which is the earliest warning.
Eliminate options that are symptoms of the opposite condition (hypomagnesaemia, like tingling) or are non-specific (cool skin, rapid pulse).
Select the option that represents the earliest sign in the toxic progression, which is 'Decreased deep tendon reflex'.

Concept Tested & Keywords

Concept Tested: Nursing assessment and monitoring for magnesium sulphate toxicity.
Stem keywords: magnesium sulphate, hypomagnesaemia, important sign, nurse
Lead-in keywords: note first
Negative lead-in flag: NOT changes the reasoning strategy; look for the exception or incorrect statement rather than the true statement.

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E6 Pharmacology Nursing Lilley 11e Part 3 p. 212-214

E6 Obstetrics Williams p. 31-51