A patient with a head injury has orders for D5NS at 25 mL/hour. The IV tubing calibration is 10 gtt/mL. What is the rate in drops per minute (nearest whole number)?

A patient with a head injury has orders for D5NS at 25 mL/hour. The IV tubing calibration is 10 gtt/mL. What is the rate in drops per minute (nearest whole number)?

• A. 2 gtt/min
• B. 3 gtt/min
• C. 4 gtt/min
• D. 5 gtt/min

Answer: (C)

Calculating IV flow rate in drops per minute uses the drip factor to convert milliliters per hour into drops per minute. Multiply the volume per hour by the drip factor: 25 mL/hour × 10 gtt/mL = 250 gtt/hour. Then convert to minutes by dividing by 60: 250 ÷ 60 ≈ 4.17 gtt/min, which rounds to 4 gtt/min. So the rate is about 4 drops per minute. This aligns with using the formula rate = (volume per hour) × (drip factor) / 60.

Calculating IV flow rate in drops per minute uses the drip factor to convert milliliters per hour into drops per minute. Multiply the volume per hour by the drip factor: 25 mL/hour × 10 gtt/mL = 250 gtt/hour. Then convert to minutes by dividing by 60: 250 ÷ 60 ≈ 4.17 gtt/min, which rounds to 4 gtt/min. So the rate is about 4 drops per minute. This aligns with using the formula rate = (volume per hour) × (drip factor) / 60.