Question

Which one of the following parameters is NOT necessary for monitoring during magnesium sulphate therapy for eclampsia?

• A. Central venous pressure
• B. Respiratory rate
• C. Patellar reflex
• D. Urinary output

Hint:

Think about what the body needs to clear magnesium and what early toxicity looks like.

Answer 1

The Correct Option is A

Magnesium sulphate is given in eclampsia to stop and prevent fits, but the gap between a working dose and a toxic dose is small. Because of this, three bedside checks are done before every repeat dose and through the infusion.

1. Central venous pressure: This number tells us about vein filling and heart preload. It plays no part in spotting magnesium toxicity, so it is not part of the standard checklist for this drug.
2. Respiratory rate: As magnesium rises above the safe range, breathing slows down. A rate under 12 to 14 breaths a minute signals toxicity, so this is checked often.
3. Patellar reflex: The knee jerk fades before any other sign of toxicity appears. Checking it before each dose is the single most useful bedside test.
4. Urinary output: The kidney is the only way magnesium leaves the body. Output under 25 to 30 mL an hour warns that the drug is building up, so hourly urine measurement is required.

The three checks that truly matter here are the knee reflex, the breathing rate, and the urine output. Central venous pressure belongs to fluid management, not magnesium safety, so it is the one that is not necessary.

Let's summarize:

• Magnesium toxicity progresses in order: reflex loss, then slow breathing, then cardiac effects.
• Reflex, respiration, and urine output form the standard monitoring triad; central venous pressure does not.

So the parameter that is not necessary for monitoring magnesium sulphate therapy is central venous pressure.