Health and medicine: how does an ultrasonic nebulizer work?

If you don't have a breathing problem from a condition such as asthma or cystic fibrosis, the term "ultrasonic nebulizer" might sound like an exotic form of execution or torture used by some of the more aggressive alien races in "Star Trek" episodes. In fact, ultrasonic nebulizers are a boon for adminstering medications for various breathing problems. But what do they do, and how do they do it?

Nebulizers in general provide medicine in a mist form, and are often used by people who have problems using the proper technique with inhalers. Often, young children have such problems. Adults can sometimes have difficulties as well, if they lack of hand strength or coordination, either from a medical condition or advanced age. Since improper techniques can mean getting too little medication, nebulizers serve an important role for inhaled medications when an inhaler just doesn't do the job.

Where ultrasonic nebulizers differ from more traditional nebulizers is in the method of turning the medication into an easily inhaled "fog."

Standard nebulizers use a piston-style air compressor to force air into the hand-held portion of the nebulizer, and this air pressure sprays the medication out into a mist form, which the person inhales through a device that inserts into the mouth, or a mask that fits over nose and mouth.

Ultrasonic nebulizers, in contrast, use high-frequency vibrations to turn the medicine into a mist. With many of these machines, the user must put water into the device, which is the medium that carries the vibrations from the ultrasonic transducer to the medicine cup. There are brands, however, that don't require a water source to carry the vibrations. Such devices are more convenient than water-based ultrasonic nebulizers, of course, since a person on the go using a portable device wouldn't have to go searching for water to refill the nebulizer.

One of the selling points of ultrasonic nebulizers is that the mist they produce has more consistent, uniform and smaller particle size compared to compressor-style technology. Particle size with standard nebulizers can be more varied and larger, simply because the air pressure produced by the compressor may vary in strength, whereas ultrasonic vibrations are more reliable and steady.

Why is particle size important, when the particles are small enough to be a mist either way? Simply put, the theory is that more uniform, smaller particle sizes makes the medicated mist penetrate more deeply into the lungs and do its work more effectively. But for the most part, it's just that: A theory.

Thus far, medical studies have only shown a proven benefit of ultrasonic nebulizers over standard nebulizers in users who have cystic fibrosis. That being said, many people with breathing problems, particular those with asthma, "feel" that they get better treatments with ultrasonic nebulizers. And when it comes to quality of life, how the patient feels about the treatment can be critical. So, for some, the extra investment in ultrasonic technology may be worth it.

Another advantage of the ultrasonic technology is that a complete treatment can often be finished in less time than with compressor-style technology.

In addition, without the need for an air compressor, ultrasonic nebulizers tend to be very quiet. With a nearly silent medication-adminstering device, users can get their medication without disrupting conversations or other activities, such as listening to music, watching television or listening for a knock at the door.