A post-operative patient is received in post-operative ward. On duty doctor ordered inj. Meperidine 25 mg IV, Inj. hydroxyzine hydrochloride 50 mg IV and inj. Glycopyrolate 0.2 mg IV. These medicines available in following dose Inj. Meperidine 50 mg/ml, Inj. hydroxyzine hydrochloride 100 mg/2 ml and inj. Glycopyrolate 0.3 mg/ml. on duty nursing officer is calculating the doses. How much total dose in ml to be infused to this patient?

1. A

   1.5 ml

2. B

   4 ml

3. C

   2.5 ml

4. D

   3 ml

Appeared in: NORCET 3 - 2022 (Shift-2)

Explanation

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• The core task is to calculate the volume in mL for three different IV medications and find their sum.
• The standard formula is applied: Volume = (Dose Ordered / Dose on Hand) × Volume Available.
• For Hydroxyzine, the available dose is 100 mg in 2 ml, which must be simplified to a concentration of 50 mg/ml before calculating.
• Calculation for Meperidine: (25 mg / 50 mg) × 1 ml = 0.5 ml.
• Calculation for Hydroxyzine: (50 mg / 50 mg) × 1 ml = 1.0 ml.
• Calculation for Glycopyrrolate: (0.2 mg / 0.3 mg) × 1 ml = 0.666... ml, which is rounded to 0.67 ml.

Why Other Options Were Wrong

• Option A: 5 ml is an incorrect calculation. This value might be reached by adding the volumes of Meperidine (0.5 ml) and Hydroxyzine (1.0 ml) but omitting the Glycopyrrolate.
• Option B: 4 ml is a significant overestimation and does not correspond to the correct calculation. This could result from gross miscalculation, such as adding the full volumes of the vials without considering the ordered doses.
• Option D: 3 ml is an overestimation. This might result from incorrectly rounding the Glycopyrrolate dose significantly upward or other calculation errors.

Related Visual

• Visual 1: Infographic: 'The Formula for Safe Drug Calculation'. This visual would clearly display the formula: Volume = (Dose Ordered / Dose on Hand) x Volume Available, with labeled examples to guide the user.
• Visual 2: Chart: 'Common IV Medication Calculations'. A chart showing examples of calculating doses for different types of medications (e.g., mg/ml, units/ml) to reinforce the process.

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 dose calculation is a fundamental and critical nursing skill to prevent medication errors and ensure patient safety. Errors can lead to underdosing (ineffective treatment) or overdosing (toxicity).
• This combination of drugs is often used for procedural sedation or post-operative comfort. Meperidine (opioid analgesic) for pain, Hydroxyzine (antihistamine) for sedative and antiemetic effects, and Glycopyrrolate (anticholinergic) to reduce secretions.
• Nurses must always perform the 'five rights' of medication administration: right patient, right drug, right dose, right route, and right time. Double-checking calculations, especially for IV medications, is a crucial safety practice.

How to Approach the Question

• First, identify the goal: to find the total volume in ml for three separate medications.
• Recall or look up the standard drug calculation formula: Volume = (Dose Ordered / Dose on Hand) × Volume Available.
• Address each medication one by one. For drugs supplied in a volume other than 1 ml (like Hydroxyzine 100mg/2ml), first calculate the concentration per 1 ml (50 mg/ml).
• Perform the calculation for each of the three drugs.
• Sum the resulting volumes from all three calculations to get the total volume.
• Compare your final calculated total (2.17 ml) to the given options and select the one that is numerically closest (2.5 ml).

Concept Tested & Keywords

• Concept Tested: Drug Dosage Calculation
• Stem keywords: post-operative, dose calculation, Meperidine, hydroxyzine hydrochloride, Glycopyrolate, IV
• Lead-in keywords: How much total dose
• Clinical cues: The care setting changes urgency, monitoring level, and the expected nursing action.

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