While current and even old continuous positive airway pressure (CPAP) flow generators can successfully treat the majority of patients with obstructive sleep apnea (OSA), it is the need for better patient compliance that appears to be driving innovation and new technology in today’s PAP devices.

CPAP has come a long way since professor Colin Sullivan developed the first system in 1981. More than 25 years later, the new generation of flow generators has evolved to become more portable, quieter, and improved with more adjustable features. New flow generator modalities have evolved such as variable/bilevel pressure for both inhalation and exhalation, automatic titration, as well as proprietary “Flex” and “EPR” pressure-relieving algorithms that anticipate respiratory events and automatically adjust the unit’s air pressure. Yet, when manufacturers are asked about the latest trends in CPAP technology for sleep, their answers are fairly consistent:

“We find that the ongoing and perennial Holy Grail is still compliance and making therapy more comfortable and more palatable for patients,” says Gretchen Jezerc, director of US marketing for sleep disordered breathing, Respironics Inc, Murrysville, Pa.

Likewise, Justin Callahan, president of the North American division at Fisher & Paykel Healthcare, Irvine, Calif, says, “Everything we do here is really focused around developing technologies that are going to further improve the patient’s acceptance of that therapy, whether that’s due to the CPAP machine or due to the patient interface.”

The CPAP industry is reacting to several studies over the years that have indicated that as many as 25% to 54% of patients discontinue using PAP therapy.1-3 Patients report many reasons for stopping therapy. Among them are:

  • Headgear and flow generator interfaces are uncomfortable,
  • Patients feel claustrophobic while using the devices and/or interfaces,
  • Interfaces and machines are perceived as too complicated to assemble or maintain,
  • Lifestyle issues, such as devices being too cumbersome to take on trips, or being difficult to use while watching TV or reading oneself to sleep; and
  • Physical side effects, such as congestion, nose bleeding, and skin irritations.

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Consequently, the new generation of PAP modalities is being designed not only to be more effective for clinically treating OSA, but to be minimally invasive, convenient, and as comfortable and close to mimicking an individual’s natural breathing as possible. At the same time, manufacturers are developing new methods for monitoring compliance and the device’s efficacy for the patient.


CPAP manufacturers are focusing on their own particular areas of innovation to improve their PAP modalities and attract physicians and patients to their devices’ new enhancements.

For some manufacturers, the answer is improving pressure relief so that the patient’s breathing pattern feels more natural. Two pressure-relieving technologies dominate the market today. C-Flex™ for CPAP is a proprietary pressure-relieving system developed by Respironics Inc.

EPR™ (Expiratory Pressure Relief) is a patented system created by ResMed Corp, Poway, Calif, for select flow generators. The company recently introduced an auto-adjusting bilevel version of its EPR technology called the VPAP™ Malibu. The device’s algorithms are able to provide varying inspiratory PAP and expiratory PAP levels that can increase or decrease based on the presence of apneas, snoring, and other flow limitations.

Respironics REMstar® Auto M Series with A-Flex CPAP System
VIASYS Healthcare BreatheX Journey

Mick Farrell, vice president of marketing for ResMed, says, “When noncompliant OSA patients breathe on the Malibu, they have said that it feels like a natural breathing pattern. That’s definitely an area that has huge potential in noncompliant OSA patients.”

Similarly, Respironics has adapted its C-Flex expiratory pressure-relieving feature for CPAP and introduced A-Flex, a pressure-relief algorithm designed for its REMstar Auto M unit. If breathing events occur, the auto algorithm raises the A-Flex pressure profile to eliminate those events, while simultaneously making sure that pressure never rises to an uncomfortably high level. In addition, Respironics has a B-Flex algorithm available for its bilevel units.

Fisher & Paykel’s solution to better patient comfort and compliance is optimizing its humidification technology. “From our angle, humidification has been our expertise for many, many years,” says Callahan. “We do a lot with humidity in the acute part of the marketplace with our ventilator products, and we’re using our knowledge to try to bring that into the home environment for CPAP.”

The result of Fisher and Paykel’s humidification focus was last year’s introduction of ThermoSmart™, a heated breathing tube that delivers high customized humidity levels that are independent of ambient temperature changes. ThermoSmart is also designed to prevent condensation within the tube. Patients experience fewer side effects such as congestion and skin irritations due to airflow through the nasal passage, and the company believes they will be more comfortable—and therefore more accepting of CPAP therapy.

For VIASYS Healthcare Respiratory Care, Yorba Linda, Calif, comfort and portability are key components to improving patient compliance. Its BreatheX CPAP from its recently acquired subdivision, Hoffman Laboratories, Chatsworth, Calif, is a completely portable CPAP system that the patient can wear like a U-shaped neck pillow. The unit is lightweight, runs cool, and can use a rechargeable 12-hour battery power throughout the night, so there is no need for electrical cords. Because of its U-shaped, self-contained design, there are no air hoses reaching across to a night table. Instead, the entire CPAP and interface rest on the patient’s chest and face.

Fisher & Paykel SleepStyle™ 600 CPAP Series

Steve Birch, director of marketing for sleep diagnostics and therapy at VIASYS, says that the BreatheX unit is ideal for active sleepers as well as business travelers. Currently, the only unit available is a standard CPAP modality, but Birch says that other common CPAP features will be incorporated in the near future. He says, “We’re looking forward to producing a complete line of CPAP devices, with the idea that they would have this same level of portability and be designed more around how the user wants to use them, while fitting them into their lifestyle.”


Improving the comfort and fit of masks, tubing, and other interface accessories is another way that PAP manufacturers are meeting the demand for greater comfort and compliance. For interfaces, this means designing devices that are least invasive to the patient, such as nasal pillow interfaces.

Birch says, “I think these days we’re trying to get away from sealing all over the nose, because you only need to seal somewhere around the nares. To the extent that you can do that reasonably well and reasonably comfortably, that has a number of other benefits. Aside from not causing the problems at the bridge of the nose with necrosis and leaks into the eyes—which is a secondary issue in that same area—pillows have different ways of riding the tubing up over the head or down below the chin.”

Nasal devices also keep the face clear, which can minimize or eliminate claustrophobia. For convenience, they allow patients who are sitting in a chair and watching television or reading to put on their glasses and take them off, which generally cannot be done with masks that come up to the nose.

Callahan says, “There are some physical limitations to how small and noninvasive you can make a device, but the materials we’re using now, such as silicon, are much better. It’s much more comfortable, and we’re learning more and more about that.”

Aside from making interfaces more comfortable, manufacturers are attempting to make them as simple as possible to assemble. Callahan says that an increasing number of manufacturers are researching how to design interfaces so that one day a patient will be able to take a CPAP and an interface out of the box, put on the interface, turn on the flow generator, and have the whole system work effectively, simply, and comfortably.

Following this trend, Respironics has recently introduced System One, which incorporates a product and customer support philosophy that was designed to work optimally together. System One’s current products include the OptiLife mask, which has been specifically engineered to work with Respironics’ REMstar Auto M Series with A-Flex. At the same time, the individual units of System One can still be used with other brands.


Medicare and insurance companies are progressively more concerned about paying home medical equipment (HME) providers for noncompliant patients who keep their CPAP machines idle by the bedside. As a result, payors are now asking CPAP providers for some type of compliance monitoring.

The least sophisticated CPAP monitoring records patient use data and then has the equipment provider call the patient for the data or has the patient bring the entire CPAP unit to the provider to collect the data. But this method is not convenient for the patient or the provider. Consequently, CPAP manufacturers have responded by incorporating monitoring systems that can download data into memory cards that can be brought or mailed to a physician or HME provider’s office.

If that system is too cumbersome for the patient, HMEs may be able to provide remote compliance systems. DeVilbiss, a division of Sunrise Medical Inc, Longmont, Colo, uses its SMLINK-300 to connect some of its CPAP products to health care providers via a phone line. The device not only transfers usage data, but also enables physicians to remotely adjust parameters for some models.

In addition, ResMed has a wireless monitoring system called ResTraxx. The device attaches to select CPAP machines and uses cellular technology to transfer monitoring data to the HMEs or health care providers.

The most sophisticated monitoring systems will report not only time spent on the device, but also data such as pressure rates, leak rates, and apnea-hypopnea index. The data can then be somehow uploaded into patient management software.


With the success and clinical effectiveness of new PAP modalities such as APAP, bilevel, and pressure-relief technologies, one wonders whether standard CPAP will eventually become extinct. However, manufacturers say that standard CPAP will likely remain the leading modality for several reasons.

First, standard positive airway pressure devices have been proven to be an effective therapy for OSA. Though it has its shortcomings and side effects that can lead to noncompliance, manufacturers are well aware of those issues and are aggressively competing with each other to make the CPAP therapy as comfortable as possible.

Second, standard CPAP is far less expensive than the more sophisticated modalities. Insurance companies generally reimburse at a single rate for CPAP therapy devices, although premiums are paid for some accessories, such as humidification, and bilevel modalities. However, there is typically little or no extra reimbursement for auto-titrating modalities or those with pressure-relieving technology, though these devices are more expensive than standard CPAP models. Consequently, it is up to the HME provider to incorporate the extra costs for the more sophisticated systems or carry more basic models. With the advent of Medicare competitive bidding and pressures from HMOs and third-party payors to reduce costs, manufacturers say that there will always be demand for lower cost models as a starting therapy. If patients prove to be noncompliant, the next line of therapy will be the more sophisticated modalities.

Sleep professionals are also not convinced that more sophisticated modalities lead to higher rates of compliance. In fact, an Italian study in 2003 concluded that patients who used automatic CPAP were no more compliant than those who used standard CPAP, but that a trial of automatic CPAP may be warranted when standard CPAP is rejected by the patient.4

That being said, Farrell still believes that the more sophisticated modalities will increase their market share, especially as prices come down. He says, “With the comfort levels and adherence that we’re seeing with EPR, with Autoset, and with Malibu, I think that the high algorithm share of the market will increase steadily over the coming years.”

Tor Valenza is a staff writer for Sleep Review. He can be reached at .


  1. Kribbs NB, Pack AI, Kline LR, et al. Objective measurement of patterns of nasal CPAP use by patients with obstructive sleep apnea. Am Rev Respir Crit Care Dis. 1993;147:887-95.
  2. Reeves-Hoche MK, Meck R, Zwillich CW. Nasal CPAP: an objective evaluation of patient compliance. Am J Respir Crit Care Dis. 1994;149:149-154.
  3. Waldhorn RE, Herrick TW, Nguyen MC, O’Donnell AE, Sodero J, Potolicchio SJ. Long-term compliance with nasal CPAP therapy of obstructive sleep apnea. Chest. 1990;97:33-38.
  4. Marrone O, Resta O, Salvaggio A, Giliberti T, Stefano A, Insalaco G. Preference for fixed or automatic CPAP in patients with obstructive sleep apnea syndrome. Sleep Med. 2004;5:247-251.