Technology Meets Tenacity

With a hard-fought blessing from the AASM finally in hand, officials at Minnesota-based Dymedix Corp are aggressively marketing their Piezo Film Effort Belt.

It’s hard enough to introduce new technology to the medical world, but add a bit of unfortunate timing and it can seem downright impossible. Jim Moore, vice president and general manager of Dymedix Diagnostics Inc, faced both barriers in an attempt to gain wide acceptance for his company’s Piezo Film Effort Belt.

Based on the science of Piezo and Pyro electric principles (not to be confused with Piezo ceramic), the Dymedix belt uses polyvinylidene fluoride (PVDF), a technology now used in many sophisticated applications such as rate responsive pacemakers, ultrasound, seismic accelerometers, and advanced naval sonar. In 1998, Dymedix’s founder Peter Stasz, invented sleep sensors using PVDF to accurately measure airflow, snore, and movement.

The invention worked well, but the scientific proof to back it up was just short of what the American Academy of Sleep Medicine (AASM) wanted back in 2008. At that time, the AASM made its influential sensor recommendations to de-emphasize the Piezo crystal respiratory effort belt in favor of esophageal manometry and the respiratory inductance plethysmography (RIP) effort belt system. “The reviewing committee did not have the opportunity to review our technology before they made their recommendations,” laments Moore, who is based in Minnesota. “As a result, we were essentially squeezed out by our competition when we tried to continue to sell our Piezo Film Effort Belt.”

The AASM recommendation carried considerable weight, and it was a frustrating setback by all accounts. Sleep labs hesitated to adopt the technology, fearing that they might lose accreditation if they went with Dymedix. The fear was unfounded, but such perceptions can take years to overcome.

Moore and his colleagues were undaunted. They called Susan Redline, MD, MPH, at Case Western Reserve University (now a professor at Harvard Medical School). Redline did a study with 50 patients to compare RIP, PVDF, and pneumotech in a head-to-head study. After seeing Redline’s favorable results published in a peer-reviewed clinical journal, AASM officials took a new look at Dymedix technology late last year.

“On Dec 19, 2011, the AASM board accepted our technology,” says Moore. “And that has opened the gates for us. Now that we are on a level playing field with RIP technology, we are enjoying success with our PVDF Film Effort Belts.”

Dumbfounded by the Precision
While the coveted AASM recommendation came in December 2011, the Dymedix product has been on the market for many years. Albeit hampered by the lack of an AASM blessing, the product has still managed to gain a steady following. “The technology kept our customers happy,” says Janine Erkenbrack, director of Sales, Dymedix. “The technology is what sells Dymedix, and it is what kept the company going pre approval and post. It speaks for itself. When sleep center techs take our belts, plug them in, and run a clinical study, they are dumbfounded by the precision, accuracy, and reliability of the signal.”

Erkenbrack had supreme confidence in the technology, which made it all the more frustrating that so many potential customers shied away at first. These days she freely takes on existing technologies. “If facilities are tired of positional issues, signal loss, or plain not holding up, they will remove those issues due to the properties of the PVDF film and the construction and design of the product,” she says. “Often with RIP technology, there are batteries that must be changed frequently. Techs don’t have to change batteries in our belt. They are warranted for one year, and we have customers using our belts for well over 2 years.”

Sleep Industry “Still Asleep”
Reinhold Henke, director of Engineering at Dymedix, says PVDF is ideal for instantaneously measuring the slightest change in temperature, pressure, or motion. As a treated form of plastic, the film is polarized with an electric charge, and sensitive to temperature changes and vibration.

Integrated with the belt, the technology measures the effort expended to breath.—the same technology used in our airflow sensor which measure nasal and oral airflow beautifully. “Dymedix’ use of PVDF produces what many have claimed to be a better signal than any thermistor, thermocouple, standard air pressure transducer, or RIP effort belt can,” says Henke. “Unfortunately, many people have confused the Piezo electric properties of PVDF and Piezo crystals. They are completely different. However, because of many peoples’ dissatisfaction with Piezo crystal belts and pressure sensors, they have mistakenly believed Piezo is Piezo, which is simply incorrect. That’s like comparing a pizza pie and an apple pie.”

“The film is perfect for this industry because it stretches and breathes along with the skin,” continues Henke. “When we take a strong signal, reduce it, and attenuate it, you get an impeccable signal with little noise, and that is what our customers see.”


INFO BOX: Around the Country
Dymedix will bring its 20’ by 20’ booth to shows around the country, including:

  • The 26th Annual Meeting of the Associated Professional Sleep Societies, Boston
  • The Focus Spring Show at the Gaylord Opryland Hotel, Nashville
  • Dymedix will also attend about eight smaller regional shows


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