A patient is ordered 2 mg morphine. Available vial contains 10 mg per ml. Find the amount of drug to be administered in ml.

Appeared in: KPSC Staff Nurse - 2021

Explanation

The core task is to calculate the volume of medication to administer based on the ordered dose and the available concentration.
The standard formula is: Volume = (Desired Dose / Dose on Hand) x Volume on Hand.
Given: Desired Dose = 2 mg, Dose on Hand = 10 mg, Volume on Hand = 1 mL.
Calculation: (2 mg / 10 mg/mL) = 0.2 mL.
This calculation ensures the patient receives the exact prescribed therapeutic dose.

Option A: Administering 0.1 mL would only provide 1 mg of morphine (0.1 mL * 10 mg/mL), which is half the prescribed dose and would likely be sub-therapeutic.
Option C: Administering 0.4 mL would deliver 4 mg of morphine (0.4 mL * 10 mg/mL), which is double the prescribed dose and increases the risk of adverse effects like respiratory depression.
Option D: Administering 0.5 mL would deliver 5 mg of morphine (0.5 mL * 10 mg/mL), which is 2.5 times the prescribed dose and constitutes a significant overdose, posing a serious safety risk.

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 fundamental nursing responsibility to prevent medication errors and ensure patient safety.
Morphine is a high-alert medication due to its narrow therapeutic index and high risk of causing significant patient harm (e.g., respiratory depression) when used in error.
Nurses must always perform the 'three checks' and adhere to the 'rights of medication administration' before giving any drug, especially opioids.

How to Approach the Question

Identify the question type: This is an analytical, dosage calculation question.
Identify the key values provided: Desired Dose (2 mg) and Stock Concentration (10 mg/mL).
Recall the standard dosage calculation formula: Volume = (Desired Dose / Stock Concentration).
Substitute the values into the formula: Volume = 2 mg / 10 mg/mL.
Perform the calculation to find the volume in mL: 0.2 mL.
Compare the calculated answer with the given options to select the correct one.

Concept Tested & Keywords

Concept Tested: Drug Dosage Calculation
Stem keywords: ordered 2 mg morphine, vial contains 10 mg per ml, amount of drug, administered in ml
Lead-in keywords: Find

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E6 Nursing Fundamentals Potter Perry 12e Part 3 p. 142-144

E6 Nursing Fundamentals Taylor p. 848-850

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