One litre of Hartmann's solution is given IV. For the first 6 hours the rate is 85 mL/h, then the rate is reduced to 70 mL/h. What is the total time required to deliver the full volume?

One litre of Hartmann's solution is given IV. For the first 6 hours the rate is 85 mL/h, then the rate is reduced to 70 mL/h. What is the total time required to deliver the full volume?

• A. 12 h
• B. 13 h
• C. 14 h
• D. 13 h 30 min

Answer: (B)

Start with the total volume to infuse: 1000 mL. In the first 6 hours at 85 mL/h, the infused amount is 6 × 85 = 510 mL. So, 1000 − 510 = 490 mL remains. At the lower rate of 70 mL/h, time for the remaining 490 mL is 490 ÷ 70 = 7 hours. Add the initial 6 hours: 6 + 7 = 13 hours. The full 1000 mL is delivered in 13 hours.

Start with the total volume to infuse: 1000 mL. In the first 6 hours at 85 mL/h, the infused amount is 6 × 85 = 510 mL. So, 1000 − 510 = 490 mL remains. At the lower rate of 70 mL/h, time for the remaining 490 mL is 490 ÷ 70 = 7 hours. Add the initial 6 hours: 6 + 7 = 13 hours. The full 1000 mL is delivered in 13 hours.