March 26, 2001 -- Whatever floats your boat may not float your asthma inhaler.
For years, people with asthma who use inhalers have been told to put them in water to see how or whether they float. This way, a person could tell whether they need to refill their inhaler with medication.
But new research presented at last week's annual meeting of the American Academy of Allergy, Asthma and Immunology in New Orleans suggests that floating is not an accurate way to determine how much medication is left in an inhaler.
Thus, floating can have potentially devastating effects if, say, a person uses an empty inhaler during an asthma attack.
Researchers led by John J. Oppenheimer, MD, of Pulmonary and Allergy Associates in Springfield, N.J. floated 15 canisters each of three popular metered dose inhalers: Proventil HFA, Flovent, and Azmacort. For the experiment, they used both conventional inhalers that use gas to propel the medication out and the newer inhalers that contain medication in a powdered form.
Regardless of the type of inhaler used, "the floating method is not an accurate method to identify the amount of inhaler contained within an inhaler device," Oppenheimer and colleagues conclude. "Manufacturers must develop more reliable means of showing the patient the contents contained within their inhaler device."
"There are some people who float their inhalers," says Ann Rosenwasser, RN, an asthma nurse at the National Jewish Medical and Research Center in Denver. "It has been used for years." But she agrees that floating is not an accurate way to determine the amount of medication left in an inhaler.
But she tells WebMD that measuring how much medication is left can be as easy as 1-2-3.
Rosenwasser tells her patients to start by dating their inhaler when they first open it and then look on the inhaler to see how many doses it contains.
Let's say you take two puffs, twice a day, she explains. "That's four puffs, and if it's a 30-day month, that means you take 120 puffs that month. So if your inhaler has 200 puffs, do a little math and you will find that there are 80 puffs left, so [you] know when to get a refill."
This math method works best for people who use their medication on a daily basis, Rosenwasser says. "But some people use their inhaler just when they have a flare-up, and it can get a little tricky, but they should at least date it when they open it and keep in mind how many doses are in a canister and how many they use," she says.
"Some of the new inhalers use dry powder, so floating can actually ruin the medicine -- a costly mistake," she tells WebMD.
Eventually all inhalers will use dry powder because chlorofluorocarbon, the gas used by conventional inhalers, damages the earth's ozone layer and is now being phased out of use, Rosenwasser notes.
Another suggestion: Talk to your doctor about using a doser, which fits on top of the inhaler and keeps track of how many puffs are left in the inhaler.
Between 12 and 15 million people, including close to five million children in the U.S., have asthma, a chronic disease in which airflow in and out of the lungs may be blocked by muscle squeezing, swelling, and excess mucus.