What is the required flow rate to deliver 2.0 litres of dextrose 4% in 1/5 normal saline over 15 hours using tubing with 22 gtt/mL?

What is the required flow rate to deliver 2.0 litres of dextrose 4% in 1/5 normal saline over 15 hours using tubing with 22 gtt/mL?

• A. 40 gtt/min
• B. 46 gtt/min
• C. 49 gtt/min
• D. 52 gtt/min

Answer: (C)

Determining IV flow rate starts with turning the prescribed volume and duration into a drops-per-minute rate using the tubing’s drop factor. First convert the total volume to milliliters: 2.0 liters equals 2000 mL. Divide by the time in hours to get the flow in mL per hour: 2000 mL ÷ 15 h ≈ 133.3 mL/h. Next, use the drop factor to convert to drops per hour: 133.3 mL/h × 22 gtt/mL ≈ 2933 gtt/h. Finally, convert to drops per minute by dividing by 60 minutes per hour: 2933 gtt/h ÷ 60 ≈ 48.9 gtt/min, which rounds to about 49 gtt/min. Therefore the needed flow rate is roughly 49 drops per minute.

Determining IV flow rate starts with turning the prescribed volume and duration into a drops-per-minute rate using the tubing’s drop factor.

First convert the total volume to milliliters: 2.0 liters equals 2000 mL. Divide by the time in hours to get the flow in mL per hour: 2000 mL ÷ 15 h ≈ 133.3 mL/h.

Next, use the drop factor to convert to drops per hour: 133.3 mL/h × 22 gtt/mL ≈ 2933 gtt/h. Finally, convert to drops per minute by dividing by 60 minutes per hour: 2933 gtt/h ÷ 60 ≈ 48.9 gtt/min, which rounds to about 49 gtt/min.

Therefore the needed flow rate is roughly 49 drops per minute.