Metered Dose Inhalers (MDI) are a true lifesaver to many, and a terrifically convenient way to deliver other medications. One of the big drawbacks to them is that there’s no really accurate way to tell if the MDI is out of medication but is just spewing out propellant. I thought I knew the answer, and it turns out I was wrong (rats).
Yahoo! News – Parents May Not Know When Asthma Inhaler Is Empty
According to experts, the only reliable way to judge whether a canister is empty is to subtract the number of doses used from the total available number listed by the manufacturer.
The new findings support this advice, according to Rubin and his colleagues, who also debunked another way some parents in the study used to define “empty”: seeing whether the medication canister floats in water. If it sinks, some parents believed, there is still medication left. If it floats, it’s empty.
Not only was this method ineffective when the researchers tested it, but it also allowed water into the canisters’ valve opening 27 percent of the time, making the practice “potentially dangerous,” they note.
Keeping track of doses by counting can be difficult and prone to error, the authors acknowledge. However, they add, until effective built-in dose counters are added to metered-dose inhalers, counting doses the old-fashioned way remains “the only accurate method” for judging when a canister is empty.
I have always thought the ‘floating upright vs. on its side’ test was accurate, but apparently not.
Somebody could retire on this idea: a foolproof way to count doses delivered, or medication remaining in an inhaler.
also posted at LingualNerve