Calculate the drops per minute for an IV infusion delivering 900 mL over 6 hours with tubing of 15 gtt/mL.

Calculate the drops per minute for an IV infusion delivering 900 mL over 6 hours with tubing of 15 gtt/mL.

• A. 36 gtt/min
• B. 37 gtt/min
• C. 38 gtt/min
• D. 39 gtt/min

Answer: (C)

Calculating drops per minute starts with turning the total infusion into a rate in minutes and then converting to drops using the tubing’s drop factor. First find the flow in mL per hour: 900 mL over 6 hours is 900/6 = 150 mL/hour. Convert that to mL per minute: 150 mL/hour ÷ 60 = 2.5 mL/min. With a drop factor of 15 gtt/mL, multiply: 2.5 mL/min × 15 gtt/mL = 37.5 gtt/min. Since you can’t deliver half a drop, round to the nearest whole drop per minute, which gives 38 gtt/min. So the rate is 38 drops per minute. The other numbers correspond to rounding down or up away from the nearest whole value.

Calculating drops per minute starts with turning the total infusion into a rate in minutes and then converting to drops using the tubing’s drop factor.

First find the flow in mL per hour: 900 mL over 6 hours is 900/6 = 150 mL/hour. Convert that to mL per minute: 150 mL/hour ÷ 60 = 2.5 mL/min. With a drop factor of 15 gtt/mL, multiply: 2.5 mL/min × 15 gtt/mL = 37.5 gtt/min. Since you can’t deliver half a drop, round to the nearest whole drop per minute, which gives 38 gtt/min.

So the rate is 38 drops per minute. The other numbers correspond to rounding down or up away from the nearest whole value.