Dextrose 5% in Lactated Ringer's solution (D5LR) 1500 mL is to be infused over 12 hours. The IV set delivers 10 drops per milliliter. What is the flow rate in drops per minute (nearest whole number)?

Dextrose 5% in Lactated Ringer's solution (D5LR) 1500 mL is to be infused over 12 hours. The IV set delivers 10 drops per milliliter. What is the flow rate in drops per minute (nearest whole number)?

• A. 27 gtt/min
• B. 21 gtt/min
• C. 18 gtt/min
• D. 24 gtt/min

Answer: (B)

The flow rate in drops per minute is found by converting the total volume to drops and dividing by the total time in minutes, using the drip factor. First, total drops = 1500 mL × 10 drops/mL = 15,000 drops. The time is 12 hours, which is 12 × 60 = 720 minutes. So drops per minute = 15,000 drops ÷ 720 minutes ≈ 20.83 drops/min, which rounds to 21 drops per minute. An equivalent way to see it is to find mL per minute first: 1500 mL ÷ 720 minutes ≈ 2.083 mL/min, and since there are 10 drops per mL, that becomes 2.083 × 10 ≈ 20.83 drops/min ≈ 21 drops/min. Therefore, the flow rate is about 21 drops per minute.

The flow rate in drops per minute is found by converting the total volume to drops and dividing by the total time in minutes, using the drip factor.

First, total drops = 1500 mL × 10 drops/mL = 15,000 drops. The time is 12 hours, which is 12 × 60 = 720 minutes. So drops per minute = 15,000 drops ÷ 720 minutes ≈ 20.83 drops/min, which rounds to 21 drops per minute.

An equivalent way to see it is to find mL per minute first: 1500 mL ÷ 720 minutes ≈ 2.083 mL/min, and since there are 10 drops per mL, that becomes 2.083 × 10 ≈ 20.83 drops/min ≈ 21 drops/min.

Therefore, the flow rate is about 21 drops per minute.