A head-injury patient has an order for 1000 mL D5NS to infuse at 30 mL/h. The IV tubing drop factor is 50 gtt/mL. What is the rate in gtt/min?

A head-injury patient has an order for 1000 mL D5NS to infuse at 30 mL/h. The IV tubing drop factor is 50 gtt/mL. What is the rate in gtt/min?

• A. 20 gtt/min
• B. 30 gtt/min
• C. 25 gtt/min
• D. 40 gtt/min

Answer: (C)

The main idea here is converting a flow rate from milliliters per hour to drops per minute using the tubing’s drop factor. Start by turning the hourly rate into a per-minute rate: 30 mL per hour equals 30 ÷ 60 = 0.5 mL per minute. With a drop factor of 50 drops per milliliter, multiply to get drops per minute: 0.5 × 50 = 25 drops per minute. So the rate is 25 gtt/min. Checks: 20 gtt/min would imply 0.4 mL/min (24 mL/h), 30 gtt/min would imply 0.6 mL/min (36 mL/h), and 40 gtt/min would imply 0.8 mL/min (48 mL/h), none of which match the order.

The main idea here is converting a flow rate from milliliters per hour to drops per minute using the tubing’s drop factor. Start by turning the hourly rate into a per-minute rate: 30 mL per hour equals 30 ÷ 60 = 0.5 mL per minute. With a drop factor of 50 drops per milliliter, multiply to get drops per minute: 0.5 × 50 = 25 drops per minute. So the rate is 25 gtt/min. Checks: 20 gtt/min would imply 0.4 mL/min (24 mL/h), 30 gtt/min would imply 0.6 mL/min (36 mL/h), and 40 gtt/min would imply 0.8 mL/min (48 mL/h), none of which match the order.