If you're having an asthma attack, you assume that with each puff of your inhaler you are getting relief. But, in many cases, it seems inhalers are being used long after they have run out of medication.
Asthma inhalers, or portable pressurized metered-dose inhalers (pMDIs), are the cornerstone of asthma treatment. But a new study reveals that patients using pMDIs do not know how to monitor the number of puffs they have taken out of their inhalers. Some didn't realize they needed to monitor their inhalers at all.
This presents a problem because every pMDI is filled with either 200 or 400 "puffs" of a bronchodilator, a medication used to open the airways and help breathing during an asthma attack. However, when these full doses are depleted, the inhaler may still "work" in that it still seems to deliver a puff, but those puffs are either greatly reduced in the amount of medication they contain, or are filled with only the propellant left in the canister.
"Although the pMDI is economic and portable, the device does not indicate how much medicine remains inside the canister once the patient starts using it," writes Nancy Sander, lead study author and the founder of Allergy & Asthma Network Mothers of Asthmatics in Fairfax, Virginia.
Noting that asthma patients had no reliable means to gauge how much medication is left in their inhalers, Sander and colleagues conducted telephone interviews with over 500 asthma patients or their families to determine how many patients are either using their inhalers too many times or tossing them too early.
Of those interviewed, 342 reported using a bronchodilator, and only 36 percent were ever told that they had to keep track of how many doses they used. More worrisome, 25 percent of these asthma patients found that their inhaler was empty during at least one asthma attack. When asked what they considered "empty" almost all—82 percent—said their inhaler was empty when nothing came out of it.
"Not having a reliable means of assessing pMDI contents is causing serious problems that need to be addressed," said Sander, who adds that on top of increased hospitalization, patients may have poorly controlled asthma as a result of taking too little medication.
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The FDA recommends that patients who use pMDIs keep track of how many times they have used it with an "asthma diary." But of those polled, only 8 percent actually kept track of the number of doses they have used.
Other means, like shaking the canister, are not accurate as every inhaler has some remaining propellant inside long after the actual medication runs out. Some patients even reported floating their inhaler to see if it had medication in it based on how high it floated in a bowl of water. This too is inaccurate and can even harm the inhaler's mechanism. "Patients do not have a reliable means of monitoring the contents of their metered-dose inhalers," said Sander.
Sanders and colleagues suggest making all inhalers with a counting device that can accurately keep track of how much medication is left in an inhaler.
"It is wholly unacceptable that so many patients, believing they are equipped with the means to manage their asthma and life-threatening episodes, are actually using an empty inhaler," she adds.
