A patient receives 750 mL of D5W over 6 hours with a drop factor of 15 gtt/mL. What is the flow rate in drops per minute?

A patient receives 750 mL of D5W over 6 hours with a drop factor of 15 gtt/mL. What is the flow rate in drops per minute?

• A. 28 gtt/min
• B. 31 gtt/min
• C. 33 gtt/min
• D. 36 gtt/min

Answer: (B)

Flow rate in drops per minute is found by turning the administered volume into drops and dividing by the total running time in minutes. Use the formula: rate (gtt/min) = (volume in mL × drop factor in gtt/mL) ÷ (time in minutes). Compute: 750 mL × 15 gtt/mL = 11,250 drops total. The time is 6 hours, which is 6 × 60 = 360 minutes. So the rate is 11,250 ÷ 360 = 31.25 gtt/min, which rounds to 31 gtt/min. This matches a practical IV rate, since you typically round to the nearest whole drop per minute when setting manual drip rates.

Flow rate in drops per minute is found by turning the administered volume into drops and dividing by the total running time in minutes. Use the formula: rate (gtt/min) = (volume in mL × drop factor in gtt/mL) ÷ (time in minutes).

Compute: 750 mL × 15 gtt/mL = 11,250 drops total. The time is 6 hours, which is 6 × 60 = 360 minutes. So the rate is 11,250 ÷ 360 = 31.25 gtt/min, which rounds to 31 gtt/min.

This matches a practical IV rate, since you typically round to the nearest whole drop per minute when setting manual drip rates.