A nurse is infusing 1500 mL NS at 75 mL/hour with a drop factor of 15 gtt/mL. Approximately how many gtt/min will be delivered?

A nurse is infusing 1500 mL NS at 75 mL/hour with a drop factor of 15 gtt/mL. Approximately how many gtt/min will be delivered?

• A. 16 gtt/min
• B. 18 gtt/min
• C. 19 gtt/min
• D. 20 gtt/min

Answer: (C)

Flow rate in drops per minute is found by converting the hourly rate to minutes and then applying the drop factor. Start with 75 mL per hour, which is 75 ÷ 60 = 1.25 mL per minute. With a drop factor of 15 drops per mL, the infusion delivers 1.25 × 15 = 18.75 drops per minute. Since you count whole drops, round to the nearest whole drop: 19 gtt/min. You can verify with total volume and total time as well: 1500 mL at 75 mL/hour takes 20 hours (1200 minutes), and (1500 × 15) / 1200 = 18.75, which also rounds to 19 gtt/min.

Flow rate in drops per minute is found by converting the hourly rate to minutes and then applying the drop factor. Start with 75 mL per hour, which is 75 ÷ 60 = 1.25 mL per minute. With a drop factor of 15 drops per mL, the infusion delivers 1.25 × 15 = 18.75 drops per minute. Since you count whole drops, round to the nearest whole drop: 19 gtt/min. You can verify with total volume and total time as well: 1500 mL at 75 mL/hour takes 20 hours (1200 minutes), and (1500 × 15) / 1200 = 18.75, which also rounds to 19 gtt/min.