A half-liter bag of dextrose 5% is set to run at 60 mL/h. After 5 hours, the rate increases to 80 mL/h. The infusion started at 0800. At what time will the infusion be completed?

A half-liter bag of dextrose 5% is set to run at 60 mL/h. After 5 hours, the rate increases to 80 mL/h. The infusion started at 0800. At what time will the infusion be completed?

• A. 1500 h
• B. 1600 h
• C. 1530 h
• D. 1700 h

Answer: (C)

Start with the total volume to infuse: 500 mL. During the first 5 hours, the rate is 60 mL/h, so the amount infused is 60 × 5 = 300 mL. This leaves 200 mL to infuse. The rate changes after 5 hours, at 1300 hours, to 80 mL/h. Time needed to infuse the remaining 200 mL at 80 mL/h is 200 / 80 = 2.5 hours (2 hours 30 minutes). Adding 2.5 hours to 1300 hours gives 1530 hours (3:30 PM). The infusion completes at 1530 h.

Start with the total volume to infuse: 500 mL. During the first 5 hours, the rate is 60 mL/h, so the amount infused is 60 × 5 = 300 mL. This leaves 200 mL to infuse. The rate changes after 5 hours, at 1300 hours, to 80 mL/h. Time needed to infuse the remaining 200 mL at 80 mL/h is 200 / 80 = 2.5 hours (2 hours 30 minutes). Adding 2.5 hours to 1300 hours gives 1530 hours (3:30 PM). The infusion completes at 1530 h.