500 mL D5 1/2 NS to run at 100 mL/hour with a drop factor of 60 gtt/mL. What is the IV flow rate in drops per minute?

500 mL D5 1/2 NS to run at 100 mL/hour with a drop factor of 60 gtt/mL. What is the IV flow rate in drops per minute?

• A. 50 gtt/min
• B. 75 gtt/min
• C. 100 gtt/min
• D. 120 gtt/min

Answer: (C)

To find the drops per minute, convert the IV rate from mL per hour to drops per minute using the drop factor. The drop factor is 60 gtt/mL, and the rate is 100 mL/hour. Use the formula gtt/min = (mL/hour) × (gtt/mL) ÷ 60. Plugging in: gtt/min = 100 × 60 ÷ 60 = 100 gtt/min. Equivalent way: 100 mL/hour is 1.667 mL/min; 1.667 mL/min × 60 gtt/mL = 100 gtt/min. The total bag volume (500 mL) doesn’t affect the rate calculation here unless you’re adjusting the time to finish the bag.

To find the drops per minute, convert the IV rate from mL per hour to drops per minute using the drop factor. The drop factor is 60 gtt/mL, and the rate is 100 mL/hour. Use the formula gtt/min = (mL/hour) × (gtt/mL) ÷ 60.

Plugging in: gtt/min = 100 × 60 ÷ 60 = 100 gtt/min.

Equivalent way: 100 mL/hour is 1.667 mL/min; 1.667 mL/min × 60 gtt/mL = 100 gtt/min.

The total bag volume (500 mL) doesn’t affect the rate calculation here unless you’re adjusting the time to finish the bag.