A drug is ordered 35 mg/hour in 500 ml normal saline, available drug is 350 mg. What would be the expected flow rate?

Appeared in: NORCET 5 mains

Explanation

The calculation involves two main steps: determining the total infusion duration and then calculating the hourly fluid rate.
First, calculate the total time the infusion will last by dividing the total drug available (350 mg) by the ordered hourly dose (35 mg/hr), which equals 10 hours.
Second, calculate the flow rate by dividing the total fluid volume (500 ml) by the total infusion time (10 hours), which results in 50 ml/hr.

Option A: This option incorrectly uses the numerical value of the drug dose (35 mg) as the flow rate (35 ml/hr), which would lead to underdosing the patient.
Option C: This flow rate is double the correct rate. It would deliver the medication twice as fast, potentially causing overdose and adverse effects.
Option D: This is an arbitrary value that does not result from any correct calculation based on the provided data. It would lead to an incorrect dose administration.

Visual 1: Formula - An infographic displaying the two-step formula for calculating IV flow rate from a drug dosage order.
Visual 2: Diagram - A diagram of an IV infusion pump with the screen displaying the calculated rate of '50 ml/hr' to reinforce the correct answer.

Clinical Relevance

Nursing practice connection: Knowing IV flow rate calculation based on drug dosage helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Accurate IV flow rate calculation is a critical nursing skill to ensure patient safety and therapeutic effectiveness, directly aligning with the 'Right Rate' and 'Right Dose' principles of medication administration.
An incorrect flow rate can lead to serious adverse events, including toxicity from overdosing or lack of therapeutic effect from underdosing.
What if the available drug was 700 mg in 500 ml? The total infusion time would be 700 mg / 35 mg/hr = 20 hours. The flow rate would then be 500 ml / 20 hr = 25 ml/hr. This shows how changes in drug concentration directly impact the flow rate.

How to Approach the Question

First, identify the question as a drug calculation problem requiring you to find the flow rate in ml/hr.
Identify the given values: Ordered dose (35 mg/hr), Total drug available (350 mg), and Total volume (500 ml).
Determine the total duration of the infusion. Divide the total drug in the bag by the hourly dose rate (350 mg / 35 mg/hr).
Once you have the total time in hours, calculate the flow rate. Divide the total volume by the total time (500 ml / 10 hr).
Compare your calculated result with the given options to find the correct answer.
Always double-check your calculations to prevent medication errors.

Concept Tested & Keywords

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