A physician orders 1000 ml of Normal Saline to be infused over 8 hours. What is the flow rate a nurse has to set if the drop factor is 15 drops per ml?

Appeared in: ISRO- 2016

Explanation

derived by applying the standard formula for calculating IV drip rates: Flow Rate (gtt/min) = (Total Volume [mL] × Drop Factor [gtt/mL]) / Time [min].
First, convert the total infusion time from hours to minutes: 8 hours × 60 minutes/hour = 480 minutes.
Next, plug the values into the formula: (1000 mL × 15 gtt/mL) / 480 min.
The calculation results in 15000 / 480 = 31.25 gtt/min.
Since drops must be whole numbers, this value is rounded to the nearest whole number, which is 31 gtt/min.

Option A: A flow rate of 20 drops per minute is incorrect. This rate would result from a significant miscalculation, possibly by using an incorrect time duration or drop factor.
Option B: A flow rate of 24 drops per minute is incorrect. This value might be obtained if one incorrectly divides the volume by the time in hours and then multiplies by an arbitrary number.
Option C: A flow rate of 28 drops per minute is incorrect. This is close to the correct answer but represents a calculation error.

Clinical Relevance

Nursing practice connection: Knowing IV Flow Rate Calculation 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. Incorrect rates can lead to fluid overload (too fast) or dehydration/sub-therapeutic treatment (too slow).
Nurses must always verify the drop factor on the IV tubing package before starting an infusion, as different sets (macrodrip vs. microdrip) have different drop factors (e.g., 10, 15, 20, or 60 gtt/mL).
What if the order was for a patient with heart failure? In that case, the nurse would need to be extra vigilant. A rapid infusion could cause fluid overload, leading to pulmonary edema. The nurse would likely use an infusion pump for precise control and monitor the patient's respiratory status and urine output closely.

How to Approach the Question

First, identify all the necessary components from the question: Total Volume (1000 mL), Total Time (8 hours), and Drop Factor (15 gtt/mL).
Recognize that the required answer is in 'drops per minute'. This is a cue that you must convert the infusion time from hours to minutes.
Recall or look up the standard formula for IV drip rate calculation: (Volume × Drop Factor) / Time in minutes.
Perform the time conversion: 8 hours * 60 min/hour = 480 minutes.
Substitute the values into the formula: (1000 * 15) / 480.
Calculate the result (31.25) and round to the nearest whole number, as partial drops cannot be administered.

Concept Tested & Keywords

Concept Tested: IV Flow Rate Calculation
Stem keywords: 1000 ml, Normal Saline, 8 hours, flow rate, drop factor, 15 drops per ml
Lead-in keywords: What is

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