The Right Tool for the Right Asthmatic

Vol. 20 •Issue 25 • Page 15
The Right Tool for the Right Asthmatic

Pair Spacers, Holding Chambers to Patients’ Needs

Despite advancements in metered dose inhalers (MDIs), dry powder inhalers (DPIs), spacers and holding chambers, it turns out the best aerosol delivery device is low-tech: cigarettes.

Smokers receive an incredible 80 percent lung deposition, Jim Fink, MS, RRT, fellow in Respiratory Science at Nektar Therapeutics in Mountain View, Calif., told delegates at the AARC Convention in Las Vegas. “Cigarettes!” he exclaimed in disbelief. “No wonder we’re at a tactical disadvantage!”

In comparison, asthmatics are lucky to receive 30 percent to 40 percent of their drugs from standard delivery devices.

Moreover, aerosol therapy pits medical devices against the body’s defenses. The upper respiratory tract, especially the nose, is naturally designed to filter out particulates before air reaches the lungs. This normally beneficial function acts against aerosols too.

Yet even aerosol particles in the ideal 1-5 micron range can’t reach the lungs if patients don’t know the proper technique. Problems include inhaling a second too early, a second too late or missing the mouth completely.

“Respiratory therapists don’t know how to use them. God knows the doctors and nurses don’t know how to use them,” he said. “So who’s going to teach the patient how to use them?”

Patient education also requires time, which no RT in a hospital can spare. Physicians, nurses and pharmacists find themselves similarly pressed. The result: Close to 60 percent of patients who get MDIs and DPIs self-administer drugs so badly they don’t get benefits. That adds up to a $7 billion in wasted therapy every year in the U.S. alone.

A National Institutes of Health study of the technology, which compared DPIs, MDIs and nebulizers, found no significant difference in effectiveness. That’s good news. However, when you consider the standard technique patients use delivers only 10 percent of the drug into the lungs, it’s clear effective therapy is in the hands of the MDI holders.

One key phrase to remember in aerosol delivery is “go slow and with the flow,” he explained.

For younger patients, who may lack the coordination to time their inhalation with the blast of medication, spacers and holding chambers are one solution that could help.

Fink performed a study comparing a wide selection of devices, including the common toilet paper roll, dubbed the poor-man’s spacer. Not to name names, but some products actually decreased the respirable dose available to the lung by 50 percent.

“Pay more money to get less drug,” he quipped. “Great idea.”

Low-volume spacers ranked about the same as the unaided MDIs. Spacers—our bargain basement toilet paper roll included—gave good protection against firing the drug one second too early but less protection against a mistimed exhalation.

“I’m just going to caution you that if you are going to use a toilet paper roll, take the paper off first,” he joked.

In comparison, holding-chamber bags and valve-holding chambers protected against both misfire and exhalation.

Fast or Slow

New non-electric static or metal spacers have the potential to get even more drugs to the lungs. “Think about this: You’re paying a lot of money for your steroids,” Fink said. “If you can get twice as much into your lungs per puff, is it worth having an accessory device? Absolutely.”

If patients, regardless of age, are receiving an MDI, they probably should get a valve-holding chamber, he asserted. Infants may benefit from a mask as long is there isn’t too much volume.

A word to the wise: Remember to use MDIs as part of a system that is compatible. It can dramatically affect deposition.

In terms of second-generation DPIs, if patients are under 6 years old, they will have difficulty generating the required 16 liters per minute of inspiratory flow. That makes it a poor choice for those with little lungs.

Also, DPIs require patients to inhale quickly. If they require medications delivered by MDIs and newer DPIs, then they may become confused at which speed to inhale. The result is known by aerosol experts as device dementia.

“Still, we as RTs need to know how to use both and optimize therapy with them,” he said.

Shawn Proctor, associate editor and Web editor, can be reached at [email protected].