The physician prescribed 1500 ml Ringer Lactate to be infused in 12 hours (1 ml = 15 drops). The drop rate would be?

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

Explanation

The question requires calculating the IV drip rate in drops per minute (gtt/min).
The formula is: Drip Rate = (Total Volume in mL × Drop Factor) / Time in minutes.
First, convert the time from hours to minutes: 12 hours × 60 minutes/hour = 720 minutes.
Next, plug the values into the formula: (1500 mL × 15 gtt/mL) / 720 min.
The calculation results in 22500 / 720 = 31.25 gtt/min.
Rounding to the nearest whole number gives 31 drops/min, as a fraction of a drop cannot be administered.

Option A: A rate of 20 drops/min is too slow. It would result in under-infusion, meaning the patient would not receive the full 1500 mL in the prescribed 12 hours. This rate would deliver only 960 mL in 12 hours.
Option B: A rate of 25 drops/min is also too slow and would lead to under-infusion. Over 12 hours, this rate would deliver only 1200 mL of the prescribed 1500 mL.
Option D: A rate of 35 drops/min is too fast. It would result in over-infusion, delivering the fluid more quickly than prescribed, which could lead to complications like fluid overload. This rate would infuse the entire 1500 mL in about 10.7 hours instead of 12.

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 drip rate calculation is a fundamental nursing skill critical for patient safety. Incorrect rates can lead to serious adverse events.
Administering fluids too slowly (under-infusion) can result in dehydration, electrolyte imbalances, and delayed therapeutic effects of medications.
Administering fluids too quickly (over-infusion) can cause fluid volume overload, leading to pulmonary edema, cardiac distress, and increased intracranial pressure, especially in vulnerable patients like the elderly, children, or those with cardiac or renal disease.

How to Approach the Question

First, identify that this is a calculation question asking for an IV drip rate.
Identify all the necessary components from the question: Total volume (1500 mL), total time (12 hours), and the drop factor (15 gtt/mL).
Recall the standard formula: Drip Rate (gtt/min) = (Volume in mL × Drop Factor) / Time in minutes.
Notice that the time is given in hours but the formula requires minutes. Convert the time: 12 hours × 60 = 720 minutes.
Substitute the values into the formula: (1500 × 15) / 720.
Perform the calculation and round the result to the nearest whole number, as you cannot have a fraction of a drop.

Concept Tested & Keywords

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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-A)

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