Lessons · Nursing · a bolus over a short time
A bolus: a set volume, fast
A bolus is a volume over a short stated time; the pump rate is volume × 60 ÷ minutes. A weight-based bolus is mL per kg times the kilograms, and then the same line.
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 order says 500 mL over 30 minutes and the pump is asking for mL/h. It is the piggyback arithmetic with a bigger bag, and a nurse who types the volume as the rate gives it over an hour instead of half of one.
How to think about it
If the order is per kilogram, find the volume first: mL/kg times kg. Then rate = volume × 60 ÷ minutes. Check that the rate is larger than the volume whenever the time is under an hour.
Worked example
Ordered 250 mL over 15 minA quarter of an hour.
Rate = 250 × 60 / 15 = 1000 mL/hFour quarter-hours in an hour, so four times the volume.
Ordered 20 mL/kg, patient 25 kg: 20 × 25 = 500 mLA weight-based bolus. The volume first.
Over 20 min: 500 × 60 / 20 = 1500 mL/hThen the rate, the same way.
Your turn
180 mL over 12 minutes. Write the pump rate line.
Rate = 180 × 60 / = 900 mL/h
Solve one, graded on the server
The trap
Typing the volume as the rate. 500 mL at 500 mL/h is an hour, and the order said fifteen minutes. The rate is what the pump would give in a whole hour, and a fifteen-minute bolus needs four times its volume.