You are required to give 1000 ml of Normal Saline over 10 hours using a micro-drip infusion set. You will adjust the drop rate (in micro-drops per minute calculated to the nearest 10 micro-drops) at:

1. A

   200

2. B

   150

3. C

   100

4. D

   50

Appeared in: GMCH - 2016

Explanation

• The standard formula for calculating IV drip rate is: Drip Rate (gtt/min) = (Total Volume in mL × Drip Factor in gtt/mL) / Total Time in minutes.
• A micro-drip infusion set has a standard drip factor of 60 gtt/mL.
• The total time for the infusion is 10 hours, which is equivalent to 600 minutes (10 hours × 60 minutes/hour).
• Plugging the values into the formula: (1000 mL × 60 gtt/mL) / 600 minutes = 100 gtt/min.
• A helpful shortcut for micro-drip sets is that the flow rate in mL/hour (1000 mL / 10 hr = 100 mL/hr) is numerically the same as the drip rate in gtt/min.

Why Other Options Were Wrong

• Option A: A rate of 200 gtt/min would infuse the 1000 ml in 5 hours, not 10 hours. This rate is twice as fast as required.
• Option B: A rate of 150 gtt/min is incorrect and likely results from a calculation error, such as miscalculating the hourly rate or using an incorrect formula.
• Option D: A rate of 50 gtt/min would infuse the 1000 ml over 20 hours, not 10 hours. This rate is half as fast as required.

Related Visual

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain IV Drip Rate Calculation as background academic context rather than a clinical decision trigger.
• Accurate IV flow rate calculation is a fundamental nursing skill critical for patient safety. Incorrect rates can lead to fluid overload (hypervolemia) or inadequate fluid/medication delivery.
• Micro-drip sets are preferred for pediatric patients, older adults, and when administering potent medications that require precise, slow infusion rates (typically less than 100 mL/hr).
• What if a macrodrip set with a 15 gtt/mL factor was used by mistake? The rate would be (1000 mL × 15 gtt/mL) / 600 min = 25 gtt/min. Using the wrong set leads to significant dosing errors.

How to Approach the Question

• First, identify all the necessary variables from the question: Total Volume (1000 ml), Total Time (10 hours), and Type of Set (micro-drip).
• Recall or look up the standard drip factor for the given set. For a micro-drip set, it is always 60 gtt/ml.
• Convert the total infusion time into minutes to match the unit required for the drip rate (drops per minute). Here, 10 hours equals 600 minutes.
• Apply the universal formula for IV drip rate: Rate = (Volume × Drip Factor) / Time in minutes.
• Substitute the values into the formula: (1000 × 60) / 600.
• Perform the calculation to find the answer and select the corresponding option.

Concept Tested & Keywords

• Concept Tested: IV Drip Rate Calculation
• Stem keywords: 1000 ml, Normal Saline, 10 hours, micro-drip infusion set, drop rate
• Lead-in keywords: calculate, adjust

Question ID

QX1uoPeDakiZ9JnD4c0XTY

Copy ID

Reference Book

E6 Pharmacology Nurses Shanbhag 3e p. 54-56

E6 Nursing Fundamentals Taylor p. 799-801

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