Proper use of a metered dose inhaler (MDI) is important not only to relieve asthma symptoms, but also to reduce the incidence of asthma-related nighttime awakenings and the sleep-deficit problems such nocturnal disruptions can produce.

Not everyone knows how to use an MDI properly, though, and sometimes it is surprising to discover just who it is that does not. Bill Pruitt, MBA, RRT, CPFT, AE-C, tells of one long-time MDI user who was in the habit of putting the mouthpiece between his lips and drawing a breath while dispensing two puffs of medication in rapid succession on that same single inhalation—patently incorrect technique. “The shocker was that this user was himself a respiratory therapist,” says the senior instructor and director of clinical education for cardiorespiratory care at the University of South Alabama in Mobile. “He of all people should have been inhaling one puff, holding it before exhaling, inhaling again, and then taking that second puff.”

Which just goes to show how critically important it is to make sure patients are thoroughly educated in the use of MDIs. Says Pruitt’s University of South Alabama colleague Tim Op’t Holt, EdD, RRT, AE-C, FAARC, a professor of cardiorespiratory care, “You must provide to patients MDI usage instruction that is clear and readily understandable, keeping in mind that MDI operation differs from one product to the next.”

Operational differences have become increasingly pronounced as the December deadline to stop US manufacture of MDIs containing chlorofluorocarbon (CFC) propellant approaches (by then, all MDIs produced in this country will be loaded with the more environmentally friendly propellant hydrofluoroalkane [HFA]). “Usage procedures for an HFA-based inhaler differ from those for a CFC type,” Op’t Holt says. “The CFC inhaler is supposed to be held away from the mouth about three finger widths, whereas the [HFA] inhaler is held inside the mouth by the lips—and hopefully inside the teeth—so that deposition doesn’t occur on the teeth and tongue.”


A metered-dose inhaler (MDI) delivers to the lungs aerosolized respiratory medication dispensed in a precise amount with the help of pressurized gas.

The device is made up of two parts. One is a canister containing the medication and the gas propellant, along with a valve that meters out the correct dose through an actuator stem. The second part is a handheld mouthpiece into which the canister fits. Pushing down on the canister after it is installed in the mouthpiece causes the dose to be dispensed. Alternatively, some MDIs are designed for actuation by the user’s breath (chiefly, Maxair, a pirbuterol product). An accessory called MD Turbo (Respirics Inc) converts most standard MDIs into a breath-actuated device.

Primarily, short-acting b2 adrenergic MDIs are intended to provide quick symptomatic relief from asthma. However, they also have application in combating several other breathing disorders, including chronic obstructive pulmonary disease. The drugs in some MDIs are long-acting controller formulations, those traditionally delivered via nebulizers and dry powder inhalers (DPIs).

A drawback to MDIs is their propensity to run out of medication before exhausting the propellant supply, according to Bill Pruitt, MBA, RRT, CPFT, AE-C, senior instructor and director of clinical education for cardiorespiratory care at the University of South Alabama in Mobile. “I’ve seen studies that suggest the drug dose begins to fall off with 20 or 30 activations remaining before the propellant is used up,” he says.

In contrast, DPIs do not have this problem because they contain no pressurized propellant. “The problem they do have is clumping of the medication if the patient inadvertently exhales back into the device,” says Pruitt. “That’s one of the advantages of MDIs. The patient can breathe back into it and it won’t cause clumping.”

Another MDI advantage is that the user need not have a strong inspiratory flow rate in order for the medication to travel down the upper airway. “With DPIs, the patient’s inspiratory flow rate must be in the range of 90 liters per minute in order for medication to be properly delivered,” says Pruitt.

Environmentally friendly though the new MDI propellant might be, it is less friendly than its predecessor when it comes to trouble-free device operation. “Hydrofluoroalkane tends to cause the medication to clog the nozzle of the MDI’s actuator stem,” says Op’t Holt. “Consequently, patients need to be instructed in how to properly clean the inhaler so they are assured of receiving the full dose of medication with each activation.”

The Book of Old Sprayings

Assurance that the patient receives—and internalizes—a full dose of MDI education is likewise important. One way to gauge the efficacy of instruction is to have the patient demonstrate back whatever information has been newly imparted, Op’t Holt suggests.

“It’s best to have the return demonstration performed with a placebo rather than the actual medication,” he says. “Unfortunately, it’s becoming more difficult to obtain training placebo. It seems as if drug companies these days often neglect to produce a training placebo to go along with whatever new asthma drug they’ve developed.” Op’t Holt recommends having the patient pantomime the return demonstration of inhaler use in the event a training placebo cannot be procured. Alternatively, the patient can dispense a dose of the actual medication while holding the inhaler off to one side of the mouth, so as not to inhale it.

Op’t Holt also considers it advantageous to end the encounter by leaving with the patient written instructions that encapsulate everything explained or demonstrated during the preceding minutes. “The patient can refer to this document later as a memory refresher,” he says.

Even the best education is meaningless if the patient chooses noncompliance afterward, however. “There are several good techniques for determining whether a patient is using the MDI when and how they’re supposed to,” says Op’t Holt. “One is to ask the patient at each visit to once more demonstrate use of the inhaler. If the patient cannot satisfactorily show you they know how to use it, the likelihood is that this individual has not been using it often enough, if at all.”

Another compliance-monitoring technique involves assessing the patient for symptoms. “If I have [patients] using the inhaler improperly, then it’s possible they will be exhibiting more symptoms,” Op’t Holt shares. “You can also ask the patient to keep a chart or diary of symptoms or peak flow readings. When next you see the patient, review their diary and note the points at which symptoms came back and peak flow decreased. Ask whether the patient was medicating at those junctures.”

Possibly the easiest way to check that the device is being used as directed is to make sure the patient is given an MDI with a built-in dose counter. “Let’s say your patient’s prescription calls for two puffs twice daily,” Op’t Holt begins. “That’s going to work out to four dispensed doses in a 24-hour period. If you see this patient once a month, then there should be 120 [fewer] doses on their MDI as tabulated by the dose counter.” The trouble is that many MDIs have no mechanism for counting doses. Op’t Holt decries this deficiency, arguing that dose counters are essential not only for monitoring compliance but also for helping patients know when an MDI is spent. “An MDI might be said to contain 200 doses, but when you get down to around dose number 196, the amount of drug dispensed at each actuation is already tailing off—it’s more propellant than anything else that’s coming out at that point.”

Delivering Compliance

Coaxing compliance from noncompliant patients can be a challenge, but Op’t Holt expresses confidence that a turnabout is achievable. “A good place to start is by reviewing with them the reason the medication has been prescribed and then explain how their symptoms will change when the medication is used and used correctly,” he says.

Although time-consuming, a phone call midway between in-person visits can also help move a recalcitrant patient into the compliant column. The ostensible purpose of the call, says Op’t Holt, is to check in and see how things are going for the patient. But it also provides an opening to gauge MDI usage compliance or to remind the patient of the benefits of proper and regular utilization. “Sometimes it helps if you can get the physician to change the prescription,” he adds. “It’s not unusual to find that the patient has been prescribed two or three different inhalers. If you can figure out a way to pare that to just one device, the patient may become more compliant simply for the reason that you’ve made utilization less of a hassle.”

In a similar vein, decreasing the number of puffs required to achieve the desired dosing can help improve compliance. “Drug companies are coming out with MDIs that have double or quadruple the amount of drug,” Op’t Holt reports. “For instance, MDIs that dispense fluticasone propionate are now available in three different dosages. By just going to the next highest dose MDI, it may be possible for the patient to have success taking one puff once a day rather than two puffs twice a day.”

Bear in mind that some patients are noncompliant because they cannot afford the medication, so be sure to inquire whether they are having difficulties obtaining the prescribed MDI owing to an inability to pay. “When I uncover a money situation that’s acting as a barrier to compliance, I try to get that patient into the pharmaceutical company patient assistance program,” Op’t Holt divulges.

Not Just for Home Anymore

In the main, MDIs have been for home or personal carry-around use. Increasingly, though, they are the respiratory drug delivery device of choice in hospitals. This is happening to some extent because of a growing body of evidence demonstrating the efficacy of inpatient treatment with MDIs. “A number of good studies show that MDIs deliver the drug to the lungs in an efficacious manner,” says Pruitt.

Another reason hospitals are making MDIs their preferred mechanism for inpatient treatment is productivity enhancement. “Many respiratory departments find MDIs speed up workflow,” says Op’t Holt. “A conventional nebulizer treatment takes 10 or 15 minutes, while an MDI treatment takes about 2. That’s because the drug dose the patient needs is delivered undiluted through the MDI in one or two sprays. If you’re expected to give 30 or 40 patients a treatment, it’s far quicker to do so with MDIs than nebulizers.”

This is not to say that MDIs are poised to relegate nebulizers to the dustbin of history. There are situations where nebulizers remain superior to MDIs. “Drug delivered by an MDI can sometimes discharge in a plume that hits the back of the throat, which results in more drug depositing in the upper airway than down in the lungs,” says Pruitt. “That’s much less likely to occur with a nebulizer.” In defense of MDIs, Pruitt points out that upper airway deposition can be minimized with the use of either a spacer or a valved holding chamber (Pruitt, incidentally, is anticipating the day when MDI spacers and holding chambers will routinely feature technology for dissipating electrostatic charges that develop as medication and propellant pass through: “The absence of electrostatic charge will allow for better delivery of the drug,” he says).

Editor’s Note
To learn more about the HFA regulation, read RT’s Respiratory Report at respiratoryreport/2007-11-21_08.asp.

Those hospitals that have been slow to embrace MDIs tend to cling to the past out of fealty to tradition. Says Op’t Holt, “Those institutions take the position that nebulizers are the way it’s always been done, the system works, so why change things? Besides, they’ll tell you that the nebulizer will always have a role, because, if you’re talking about a cohort of elderly people, those patients simply don’t have the hand-breath coordination it takes to use an MDI.”

Nonetheless, the MDI has a role to play too, and it is one that is growing by the day. Says Pruitt, “There is no question but that MDIs ought to be part of every institution’s respiratory arsenal. They are an important tool in the fight against asthma.”

Rich Smith is a contributing author to RT. For further informaiton, contact [email protected]