Doctor prescribed to administer 0.1 mg adrenaline with a ratio of 1:1000. How much ml should be administered by the nurse?

Appeared in: JIPMER Pondicherry NO - 2022

Explanation

The core task is to convert a prescribed dose in milligrams (mg) to a volume in milliliters (ml) using a given concentration ratio.
The concentration 1:1000 means 1 gram of adrenaline in 1000 ml of solution.
Converting grams to milligrams (1 g = 1000 mg), the concentration becomes 1000 mg in 1000 ml, which simplifies to 1 mg/ml.
To get the desired dose of 0.1 mg from a solution of 1 mg/ml, you need to administer 0.1 ml of the solution.

Option A: Administering 1 ml would deliver 1 mg of adrenaline (1 ml × 1 mg/ml), which is ten times the prescribed dose.
Option B: Administering 0.5 ml would deliver 0.5 mg of adrenaline (0.5 ml × 1 mg/ml), which is five times the prescribed dose.
Option D: Administering 10 ml would deliver 10 mg of adrenaline (10 ml × 1 mg/ml), a significant overdose that is 100 times the prescribed dose and potentially lethal.

Clinical Relevance

Nursing practice connection: Knowing Drug Dose Calculation helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Accurate drug calculation is a fundamental nursing skill essential for patient safety. Errors can lead to underdosing, ineffective treatment, or overdosing, causing severe harm.
Always follow the 'Six Rights' of medication administration: Right Patient, Right Drug, Right Dose, Right Route, Right Time, and Right Documentation.
What if the available adrenaline was 1:10,000? The concentration would be 1 mg in 10,000 ml, or 0.1 mg in 1 ml. In that case, to administer 0.1 mg, you would give 1 ml. This highlights why checking the concentration is critical.

How to Approach the Question

First, identify the key pieces of information: the desired dose (0.1 mg) and the available concentration (1:1000).
Translate the ratio concentration into a standard unit, such as mg/ml. Remember that 1:1000 means 1 gram in 1000 ml.
Perform the necessary conversion (grams to milligrams) to get a clear concentration (1000 mg / 1000 ml = 1 mg/ml).
Apply the standard drug calculation formula: (Desired / Have) x Volume.
Plug in the values: (0.1 mg / 1 mg) x 1 ml.
Calculate the final answer and double-check your math to ensure accuracy.

Concept Tested & Keywords

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E6 Medicine Davidson Principles Practice 24e p. 224-226

E6 Nursing Fundamentals Taylor p. 915-917

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 1419-1421

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