If 270 mL remain and the infusion is running at 30 mL/h, how many hours until completion?

If 270 mL remain and the infusion is running at 30 mL/h, how many hours until completion?

• A. 7 hours
• B. 9 hours
• C. 8 hours
• D. 10 hours

Answer: (B)

When a constant infusion rate is used, the time to finish is found by dividing the remaining volume by the flow rate. Here, the remaining volume is 270 mL and the rate is 30 mL per hour, so the time equals 270 ÷ 30 = 9 hours. You can verify this by checking: 30 mL/hour × 9 hours = 270 mL, which matches the amount left to infuse. Values like 7, 8, or 10 hours would imply delivering different total volumes (210, 240, or 300 mL respectively), which wouldn’t complete exactly at the 270 mL mark.

When a constant infusion rate is used, the time to finish is found by dividing the remaining volume by the flow rate. Here, the remaining volume is 270 mL and the rate is 30 mL per hour, so the time equals 270 ÷ 30 = 9 hours. You can verify this by checking: 30 mL/hour × 9 hours = 270 mL, which matches the amount left to infuse. Values like 7, 8, or 10 hours would imply delivering different total volumes (210, 240, or 300 mL respectively), which wouldn’t complete exactly at the 270 mL mark.