A physician prescribed 1000 ml normal saline to infuse over 8 hours (one ml = 15 drops). The nurse sets the flow rate at?

Appeared in: SCTIMST Staff Nurse - 2015 (Set-B)

Explanation

derived using the standard formula for calculating IV drip rates: Flow Rate (gtt/min) = [Total Volume (mL) × Drop Factor (gtt/mL)] / Total Time (minutes).
First, the total infusion time must be converted from hours to minutes: 8 hours × 60 minutes/hour = 480 minutes.
Next, the values are substituted into the formula: (1000 mL × 15 gtt/mL) / 480 minutes.
This calculation yields 15000 / 480 = 31.25.
Since drops can only be administered as whole numbers, 31.25 is rounded to the nearest whole number, which is 31 drops/minute.

Option A: A flow rate of 40 drops/minute is incorrect. This rate would be obtained if the total infusion time was significantly shorter than the prescribed 8 hours (approximately 6.25 hours), leading to a dangerously fast infusion.
Option B: A flow rate of 28 drops/minute is too slow. This could result from a calculation error, such as incorrectly converting the time or assuming a longer infusion period (around 9 hours).
Option D: A flow rate of 36 drops/minute is too fast. This error could arise from miscalculating the total time in minutes, for instance, by assuming the infusion should run over a shorter period like 7 hours.

Clinical Relevance

Nursing practice connection: Knowing IV flow rate calculation (drops per minute) helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Accurate calculation of IV flow rates is a critical nursing skill to ensure patient safety. An incorrect rate can lead to serious complications.
Administering fluid too quickly can cause fluid volume overload, leading to conditions like pulmonary edema and cardiac distress. Administering it too slowly can result in inadequate hydration or delayed delivery of medication.
Nurses must always double-check their calculations, especially for high-risk medications or vulnerable patients. Using a calculator and having a second nurse verify the calculation is a best practice.

How to Approach the Question

First, identify the question as a medication calculation problem requiring you to find the IV flow rate in drops per minute.
Carefully extract all the necessary variables from the problem: Total Volume (1000 mL), Total Time (8 hours), and Drop Factor (15 gtt/mL).
Recognize that the formula requires time to be in minutes. Perform the necessary unit conversion: 8 hours × 60 = 480 minutes.
Select the correct formula: Flow Rate = (Volume × Drop Factor) / Time in minutes.
Substitute the values into the formula and solve the equation: (1000 × 15) / 480.
Finally, round the result to the nearest whole number, as partial drops cannot be administered. Compare your final answer to the given options.

Concept Tested & Keywords

QSA_TOBq8lYRbLkKMIVMc9

E6 Pharmacology Nurses Shanbhag 3e p. 54-56

E6 Nursing Fundamentals Potter Perry 12e Part 5 p. 93-95

Practise the full SCTIMST Staff Nurse - 2015 (Set-B)

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