A patient requires 1200 mL of normal saline to be infused over 24 hours. The IV set delivers 20 gtt/mL. What is the rate in gtt/min?

A patient requires 1200 mL of normal saline to be infused over 24 hours. The IV set delivers 20 gtt/mL. What is the rate in gtt/min?

• A. 12 gtt/min
• B. 17 gtt/min
• C. 18 gtt/min
• D. 20 gtt/min

Answer: (B)

The rate is found by turning the total daily volume into a per-minute drop rate using the drip factor. First convert 1200 mL over 24 hours to milliliters per hour: 1200 ÷ 24 = 50 mL/hour. With a drop factor of 20 drops per mL, this becomes 50 × 20 = 1000 drops per hour. To get drops per minute, divide by 60: 1000 ÷ 60 ≈ 16.7 drops per minute, which rounds to 17 gtt/min. Why the others don’t fit: a rate of 12 gtt/min corresponds to 720 gtt/hour, which is 36 mL/hour, and over 24 hours that would be 864 mL, not 1200 mL. A rate of 18 gtt/min gives 1080 gtt/hour, or 54 mL/hour, totaling 1296 mL/day. A rate of 20 gtt/min yields 1200 gtt/hour, or 60 mL/hour, totaling 1440 mL/day. The calculated 17 gtt/min best matches the required 1200 mL in 24 hours.

The rate is found by turning the total daily volume into a per-minute drop rate using the drip factor. First convert 1200 mL over 24 hours to milliliters per hour: 1200 ÷ 24 = 50 mL/hour. With a drop factor of 20 drops per mL, this becomes 50 × 20 = 1000 drops per hour. To get drops per minute, divide by 60: 1000 ÷ 60 ≈ 16.7 drops per minute, which rounds to 17 gtt/min.

Why the others don’t fit: a rate of 12 gtt/min corresponds to 720 gtt/hour, which is 36 mL/hour, and over 24 hours that would be 864 mL, not 1200 mL. A rate of 18 gtt/min gives 1080 gtt/hour, or 54 mL/hour, totaling 1296 mL/day. A rate of 20 gtt/min yields 1200 gtt/hour, or 60 mL/hour, totaling 1440 mL/day. The calculated 17 gtt/min best matches the required 1200 mL in 24 hours.