Lessons · Nursing · a piggyback over thirty minutes
A piggyback: a small bag over a short time
A secondary bag runs over minutes, not hours, and the pump still wants mL/h: rate = volume ÷ (minutes ÷ 60), or volume × 60 ÷ minutes. A 30-minute bag runs at twice its volume per hour.
Hone is a place to practise a career, one idea a day. This is one of its lessons, written out in full and free to read without an account.
What it is for
The antibiotic comes as 100 mL to run over 30 minutes. Set the pump to 100 and it takes an hour and the next dose is late; set it to 200 and it finishes on time. The bag's volume is never the rate unless the order happens to say one hour.
How to think about it
Write the volume and the minutes. Turn the minutes into hours by dividing by 60, then divide the volume by that; or multiply the volume by 60 and divide by the minutes, which is the same thing and avoids a decimal. Then check: a bag over less than an hour runs at more than its volume per hour.
Worked example
50 mL over 30 minA small bag, half an hour.
30 / 60 = 0.5 hMinutes into hours.
Rate = 50 / 0.5 = 100 mL/hTwice the volume, because half an hour.
100 mL over 40 min: 100 × 60 / 40 = 150 mL/hThe other form of the same line. No decimal to carry.
Your turn
150 mL over 30 minutes. Write the pump rate line.
Rate = 150 / 0.5 = mL/h
Solve one, graded on the server
The trap
Setting the pump to the bag's volume. 100 mL at 100 mL/h takes an hour; the order said thirty minutes. The rate is the volume the pump would give in a whole hour, and a thirty-minute bag needs twice its volume.