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Permalink Reply by Rock Conner RRT on September 8, 2009 at 10:21am

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Permalink Reply by Rock Conner RRT on September 8, 2009 at 10:28am

Positive Airway Pressure Technology Becomes More Advanced
Smaller, Lighter, Smarter, Quieter


By Rock Conner, RRT

Twenty-five years ago, continuous positive airway pressure devices were as large as furniture, as loud as vacuum cleaners, and were not discussed in polite company. PAP innovation progressed as the medical, reimbursement, and user communities recognized and accepted obstructive sleep apnea therapies.

Today, commercial air travelers commonly may encounter a fellow flier with a well thought out briefcase that holds a cell phone, a travel PAP device, and a laptop to chat with other people about all things PAP.

In those inglorious early days of PAP therapy, we had one mode, CPAP, for one disorder, OSA. Today's devices are available with bilevel, automatically adjusting, reduced expiratory pressure, and servo ventilation features which treat a number of sleep-disordered breathing and restrictive respiratory disorders.

Standard of care
CPAP remains the standard of care for OSA. Just like in the old days, a seal is formed to maintain an intra-airway pressure splint which facilitates unobstructed spontaneous breathing during sleep.

"Continuous" is no longer strictly accurate, though, because many current devices have features which allow the limited reduction of pressure during exhalation, much as in bilevel PAP. This development has been demonstrated to improve patient adherence to CPAP therapy.

Some remarkably astute devices allow expiratory programmed pressure reduction, which is suspended if certain breathing disruptions are detected. The generally accepted CPAP maximum expiratory pressure reduction is 3 cm H2O, above which lies bilevel PAP.

In addition to those pressure variability improvements, today's CPAP devices boast advanced pressure maintenance capabilities. The motors are so responsive and the onboard microprocessors so fast that expiratory work of breathing has been decimated as the system powers down in response to patient exhalation. The difference is so profound that some users moving from older generation CPAP devices into the best of today's technology report apprehension that the pressures have been improperly programmed. The pressures are quite consistent; what is missing is the expiratory resistance to which they had become accustomed.

Lastly, the darn things are so little. Earlier CPAP devices were quite large and have decreased in size with time and innovation. Today's smarter and less costly flow generators can be held in the palm of one hand, even when packaged with integrated heated humidifiers and battery packs.

Another option
Bilevel PAP therapy is available for OSA patients unable to contend with an expiratory positive airway pressure (EPAP) equal to the inspiratory positive airway pressure (IPAP) required to maintain airway patency, and who require a split (pressure support) between IPAP and EPAP of greater than 3 cm H2O.

When complex sleep apnea appears with CPAP application, bilevel PAP with respiratory rate support may be employed. Bilevel PAP also has been shown to improve ejection fraction in congestive heart failure patients.

Optimal pressures
Automatically adjusting positive airway pressure (APAP) devices in both CPAP and bilevel models use proprietary feedback and adjustment algorithms to find and maintain optimal PAP pressures. Some protocols employ this application in lieu of titration polysomnography.

In such models, a standard PSG is performed, but instead of a following titration study, the patient takes home an APAP system. Follow-up device data downloads verify therapeutic pressures are provided.

APAP titration is somewhat controversial because the long-established industry standard includes an attended second-night PAP titration. The tightening reimbursement environment has encouraged these and other cost-reduction innovations. A version of this model is employed in some Veterans Administration sleep medicine protocols, as well as in some payer-driven sleep programs.

APAP has other benefits. Scott Lloyd, chief executive officer of Atlanta-based Extrakare LLC, cites research that associates APAP with a 13 percent nightly use increase and a 24 percent compliance improvement over CPAP.1-3 Extrakare now offers APAP as a standard of care, under certain conditions and with physician approval dispensing APAP at CPAP reimbursement levels.

"Ultimately," Lloyd said, "it is our hope that we can demonstrate an above-average rate of compliance and we will earn a larger share of referrals from sleep labs and physicians."

However, he is not a proponent of replacing the titration study with APAP. "We do not recommend skipping the titration," Lloyd noted. "We believe there are a number of important things that occur during a titration, justifying the time and expense."

Among his reasons for concern are APAP's inability to distinguish between obstructive and central apneas, and the importance of having supportive attendance during what Lloyd calls "first-night acclimation" to PAP therapy.

"As good as our respiratory therapists are, they cannot replace having a technician physically present to help patients as they use their device the first night and to answer questions the following morning," Lloyd said.
Treating complex sleep apnea
Servo ventilation devices are enhanced, face positive pressure support ventilators used to treat complex sleep apnea and periodic breathing, among other disorders. Complex sleep apnea emerges during the application of CPAP and has a central apnea component.

Periodic breathing often is seen as Cheyne-Stokes Respiration, characterized by repeated episodes of waxing and waning tidal volumes. Servo ventilation devices monitor and support flow patterns, engaging various support mechanisms when measured data points fall below tolerated norms.

Other features
Remote device access uses advancing communication infrastructures to facilitate patient compliance monitoring and remote setting adjustments. Some of these systems use device-gathering data media which must be physically transported to a reading station at a durable medical equipment dealer location, sleep lab, or physician office.

Physician orders for device settings changes can be programmed into the same media device and returned to the patient's device for reprogramming. Other systems use hardwire or wireless telephone connections to connect with proprietary data management websites.
Remote device access options can reduce the cost of gathering the PAP compliance data now required by many third party payers. Other advantages of these technologies include increased patient-physician communication and user self-monitoring.


Also, humidity control is important because too little humidity can result in patient discomfort, while excess humidity can result in reduced or subtherapeutic pressure delivery and unexpected nasal lavage, all of which negatively affect compliance rates and outcomes.

Gone are the days when PAP users were at the mercy of ambient temperature and other environmental conditions. Suffering from mucosal drying one night and then unwanted nasal irrigation the next is a burden of the past.

As pressurized, heated, and humidified gas leaves the PAP device and transits the connecting tubing to the user's mask interface, heat loss yields water vapor condensation which can result in water accumulation and interfere with algorithm feedback. Reducing heat loss affects condensation reduction.

One option is to insulate the tubing so heat loss is minimized. Commercially available tubing insulation products include parka-like wraps with zippers than run the length of the tubing and loose-fitting soft fleece wraps.

More complex devices sense temperature and respond to maintain the optimal temperature needed to minimize condensation. Some available systems track room temperature and then adjust humidifier heater control settings accordingly.

Using a room temperature tracking system with an insulating wrap is an effective condensation management approach. Other systems continue heating the gas inside the tubing all the way to the user interface so there is no resultant condensation.

The future
New applications making use of these PAP technology innovations are improving research methods and compliance. Remote device access allows better monitoring of study subjects outside the limited environment of the sleep lab and in their own environments, yielding data more representative of PAP users' experiences, environments, and outcomes.

There also is a thriving community of PAP patients who communicate via the Internet and email about their download information, advise one another about adaptation strategies, compare providers and products, and consult informally with sleep professionals.
Contemporary PAP devices are smaller, lighter, smarter, quieter, and less costly than their predecessors. Modern users have access to better equipment, monitoring, and communication about how to make use of all these advantages.

Sleep professionals are challenged and encouraged to stay current with industry developments in order to make the best options available for each PAP user. The ultimate goal of better outcomes will best be served by knowing your patient, knowing the equipment and services out there, and caring enough to make the best match in each case.

References

1. Massie CA, McArdle N, Hart RW, et al. Comparison between automatic and fixed positive airway pressure therapy in the home. Am J Respir Crit Care Med. 2003;167(1):20-3.

2. Nolan GM, Doherty LS, Mc Nicholas WT. Auto-adjusting versus fixed positive pressure therapy in mild to moderate obstructive sleep apnoea. Sleep. 2007;30(2):189-94.

3. Teschler H, Berthon-Jones M. Intelligent CPAP systems: clinical experience. Thorax. 1998;53 Suppl 3:S49-54.
Rock Conner, RRT, is a support clinician at Fusion Sleep in Atlanta.
Copyright ©2009 Merion Publications
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Publishers of ADVANCE Newsmagazines
www.advanceweb.com

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Permalink Reply by RockRpsgt on September 8, 2009 at 10:31am

Great article Rock! Good job.

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Permalink Reply by Judy on September 8, 2009 at 11:39am

Wow! We have some great writers amongst our Pros here!!! First Rock Hinkle's article for his local newspaper, this article by Rock Connor (which even tho written for a professional journal I could actually understand and enjoy!) - and then I have to confess to not having purchased or read Dr S Y Park's book despite I've heard good praise of it by those who have.

Good job, Rock! (I'd hire you! Honest, I would!) *wicked grin*

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Permalink Reply by Mike on September 8, 2009 at 12:03pm

this small article covers a lot of ground, and is very well written. thanks for bringing it to our attention.

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Permalink Reply by Rock Conner RRT on September 8, 2009 at 12:04pm

thanks everybody

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