Lessons · Pharmacy · puffs in a canister
Puffs in a canister
The canister's label says how many actuations it holds, and the days' supply is that number divided by the puffs used in a day.
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
A canister is not a bottle you can count, so the only number you have is the one printed on the box. A patient told the wrong days' supply runs out mid-week, and a rescue inhaler that runs out is not a small problem.
How to think about it
Puffs a day first: the puffs in one dose times how many doses a day. Then divide the actuations by it, and round DOWN to whole days.
Worked example
2 puffs qid = 2 x 4 = 8 puffs a dayThe dose is in puffs, so the day's worth is in puffs too.
200 actuations / 8 = 25 daysThe canister divided by a day's worth.
120 actuations / 2 puffs a day = 60 daysA smaller canister on a smaller sig lasts longer.
A prn inhaler is worked from the maximum the sig allowsOtherwise there is no number a day to divide by.
Your turn
A canister holds 60 actuations and the sig uses 4 puffs a day. Write the days' supply.
60 / 4 = days
Solve one, graded on the server
The trap
Counting doses instead of puffs. Two puffs four times a day is four doses and eight puffs, and the canister is counted in puffs.