One of the more frustrating aspects of asthma medication use is not knowing when your inhaler is empty of medication, or when it is about to become empty. Even when the medication has run out, most of the inhalers — whether they contain bronchodilator or antiinflammatory medication — will continue to make a sound when shaken (because of the remaining inactive gases still present in the cannister) and will continue to release some spray when activated. Many people often find themselves uncertain as to whether to risk using an inhaler that may have no medication in it or discard a partially empty inhaler when active (and expensive) medication is still in it.
The ideal solution would be a device that records and displays the number of “puffs” used or — even better — the number of “puffs” still remaining in the canister. Although such counters are being developed [and now exist; see information on the “Doser” in the News about Asthma section, Chapter 49], they are either limited to certain inhalers or add significantly to the cost of the inhalers.
Alternatively, two methods can be used to determine how full or empty an inhaler is. The first method involves knowing how many “puffs” are in a full canister prior to use and keeping track of how many “puffs” you have used. This technique is probably practical only if you use the same number of “puffs” each day, such as 2 puffs twice a day of a long-acting bronchodilator or 4 puffs twice a day of an inhaled steroid. It would not work well if you tend to activate the inhaler for extra “puffs” when you are uncertain as to how well you have inhaled the medication or if you use a number of different inhalers with the same medication around the house, car, and workplace.