Prescription 125 mg atropine, available 500 mg in 2 ml. How much amount should be given to the patient by a 1 ml syringe having 40 dots?

Appeared in: AIIMS Delhi NO - 2017

Explanation

The calculation begins with determining the volume needed using the formula: (Desired Dose / Available Dose) × Stock Volume.
Plugging in the values: (125 mg / 500 mg) × 2 ml results in a required volume of 0.5 ml.
The syringe is calibrated so that the full 1 ml volume contains 40 dots.
To administer 0.5 ml, which is half of the syringe's total volume, the nurse would use half of the total dots.
Therefore, half of 40 dots is 20 dots. The correct administration is 20 dots, which delivers 0.5 ml.

Option A: This option correctly identifies the volume (0.5 ml) but provides an incorrect number of dots (15). On this specific syringe, 15 dots would only deliver 0.375 ml.
Option C: Both the number of dots (25) and the volume (0.4 ml) are incorrect. 25 dots would deliver 0.625 ml, not 0.4 ml.
Option D: Both the number of dots (40) and the volume (0.6 ml) are incorrect. 40 dots would deliver the full 1 ml of the syringe, not 0.6 ml.

Clinical Relevance

Nursing practice connection: Use the key finding related to Drug Dosage Calculation to guide bedside assessment, documentation, and the next nursing action.
Accurate drug calculation is a critical nursing skill to ensure patient safety and prevent medication errors. Errors can lead to underdosing or overdosing, both with potentially severe consequences.
This question reinforces the 'Right Dose' principle, which is one of the fundamental 'Six Rights' of Medication Administration (Right Patient, Right Drug, Right Dose, Right Route, Right Time, Right Documentation).
Nurses must always double-check their calculations, especially for high-alert medications. It is also best practice to have a second nurse verify the calculation.

How to Approach the Question

First, identify all the given values: the desired dose (125 mg), the available stock (500 mg in 2 ml), and the syringe calibration (1 ml = 40 dots).
Use the standard formula to calculate the volume in milliliters (ml) to be administered: (Desired Dose / Available Dose) × Stock Volume.
Perform the calculation: (125 / 500) * 2 = 0.5 ml.
Next, determine the relationship between volume and the syringe markings. Here, 1 ml equals 40 dots.
Calculate how many dots correspond to the required volume. Since you need 0.5 ml (half of 1 ml), you will need half of the dots (40 / 2 = 20 dots).
Finally, compare your calculated result (20 dots / 0.5 ml) with the given options to find the correct match.

Concept Tested & Keywords

Concept Tested: Drug Dosage Calculation
Stem keywords: atropine, prescription, 125 mg, 500 mg in 2 ml, 1 ml syringe, 40 dots
Lead-in keywords: How much

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E6 Pharmacology Nurses Shanbhag 3e p. 55-57

E6 Nursing Fundamentals Taylor p. 915-917

Practise the full AIIMS Delhi NO - 2017

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