A unit of blood 500 mL to be infused over 4 hours using a 15 gtt/mL set. What is the drip rate in gtt/min?

A unit of blood 500 mL to be infused over 4 hours using a 15 gtt/mL set. What is the drip rate in gtt/min?

• A. 33 gtt/min
• B. 32 gtt/min
• C. 31 gtt/min
• D. 30 gtt/min

Answer: (C)

Drip rate is total drops to be delivered per minute, using the formula: drip rate = (volume in mL) × (drips per mL) ÷ (time in minutes). Here, 500 mL at 15 gtt/mL gives 7500 drops to be infused. Four hours equals 240 minutes. So 7500 ÷ 240 = 31.25 gtt/min. Since you can’t deliver a fraction of a drop, round to the nearest whole drop, which is 31 gtt/min. This matches the expected rate.

Drip rate is total drops to be delivered per minute, using the formula: drip rate = (volume in mL) × (drips per mL) ÷ (time in minutes).

Here, 500 mL at 15 gtt/mL gives 7500 drops to be infused. Four hours equals 240 minutes. So 7500 ÷ 240 = 31.25 gtt/min. Since you can’t deliver a fraction of a drop, round to the nearest whole drop, which is 31 gtt/min. This matches the expected rate.