A 1000 mL IV bag is to be infused over 8 hours using a macrodrip set of 15 gtt/mL. What is the required IV rate in mL/hr and gtt/min?

• A. 125 mL/hr (≈31 gtt/min)
• B. 150 mL/hr (≈38 gtt/min)
• C. 80 mL/hr (≈20 gtt/min)
• D. 200 mL/hr (≈50 gtt/min)

Answer: (A)

The main idea is to convert the prescribed volume and time into a flow rate in mL per hour, then translate that into drops per minute using the drip factor.

First, find the hourly infusion rate in mL/hr: 1000 mL divided by 8 hours equals 125 mL/hr.

Next, convert that to drops per minute using the drop factor (15 gtt per mL): 125 mL/hr × 15 gtt/mL = 1875 gtt/hr. Then divide by 60 to get gtt/min: 1875 ÷ 60 ≈ 31.25, which rounds to about 31 gtt/min.

So the required IV rate is 125 mL/hr and about 31 gtt/min. Other rates would not match both parts (for example, 150 mL/hr ≈ 38 gtt/min; 80 mL/hr ≈ 20 gtt/min; 200 mL/hr ≈ 50 gtt/min).