If the same 900 mL over 9 hours infusion uses a drop factor of 20 gtt/mL, what is the drops per minute (gtt/min)?

If the same 900 mL over 9 hours infusion uses a drop factor of 20 gtt/mL, what is the drops per minute (gtt/min)?

• A. 25 gtt/min
• B. 33 gtt/min
• C. 40 gtt/min
• D. 50 gtt/min

Answer: (B)

Finding drops per minute requires converting the infusion into a rate per minute using the drop factor. First determine the infusion rate in mL per hour: 900 mL over 9 hours equals 100 mL per hour. The drop factor is 20 drops per mL, so the rate in drops per hour is 100 mL/h × 20 gtt/mL = 2000 gtt/h. Convert to drops per minute: 2000 gtt/h ÷ 60 min/h ≈ 33.3 gtt/min. So the flow is about 33 gtt/min.

Finding drops per minute requires converting the infusion into a rate per minute using the drop factor.

First determine the infusion rate in mL per hour: 900 mL over 9 hours equals 100 mL per hour. The drop factor is 20 drops per mL, so the rate in drops per hour is 100 mL/h × 20 gtt/mL = 2000 gtt/h. Convert to drops per minute: 2000 gtt/h ÷ 60 min/h ≈ 33.3 gtt/min. So the flow is about 33 gtt/min.