CPAP (continuous positive airway pressure) is the gold standard for sleep apnea treatment. New treatment options are beginning to challenge the unquestioned supremacy of the CPAP machine however, including the BiPAP (bilevel positive airway pressure) machine and the ASV (adaptive servo-ventilation.
A CPAP machine prevents apneas by blowing a constant stream of air through a tube and face mask and into the patient's lungs. As the air pressure is constant, when the patient breathes out the lungs must work against the air flow in order to exhale. For many people this aspect of CPAP treatment is not a problem. Some CPAP users, however, cannot adapt to breathing against the CPAP airflow. Health complications such as heart failure may also make CPAP airflow difficult to breathe against. For people in these categories a BiPAP or ASV machine may provide more effective apnea relief.
The BiPAP (Bilevel Positive Airway Pressure)
The BiPAP, or bilevel positive airway pressure machine, is very similar to the CPAP. While a CPAP machine treats sleep apnea with one continuous air pressure, a BiPAP uses two different air pressures.
When the sleeper inhales, the BiPAP uses air pressure similar to that produced by a CPAP. As the sleeper exhales, however, the air pressure drops, making it easier to empty the lungs. The two air pressures alternate on a set timer.
A more complicated version of the BiPAP goes by the long and intimidating name of the bilevel continuous airway pressure spontaneous timed machine, or BiPAP ST (thank goodness for acronyms!). The BiPAP ST works like a regular BiPAP machine, but has a back-up response if the user stops breathing. If an apnea occurs and breathing stops for a predetermined amount of time the BiPAP responds with a higher pressure airflow to stimulate breathing. It is important to remember, however, that the BiPAP does not actually breathe for you.
ASV (Adaptive Servo-Ventilation)
The adaptive servo-ventilation machine (ASV) is one of the most recent sleep apnea treatment options, and certainly one of the most complex. A CPAP machine provides a continuous flow of air. A BiPAP has two alternating air pressures. The ASV, however, monitors and responds to every breath you take.
Rather than providing the same air pressure (or mixture of air pressures) the adaptive servo-ventilator adjusts air pressure as needed. When sleep apnea occurs, the ASV responds with air pressure that mimics approximately ninety percent of the patient's normal breathing. As the apnea ends, the ASV slowly stops providing breathing support. The result is a sleep apnea treatment that is more in tune with the sleeper's normal breathing pattern.
BiPAP, CPAP and Complex Sleep Apnea
Adaptive servo-ventilators are most often used with central sleep apnea. Unlike obstructive sleep apnea, central sleep apnea occurs due to neurological abnormalities. Patients with both heart failure and central sleep apnea often respond well to an ASV.
CPAP and BiPAP treatment for obstructive sleep apnea sometimes results in complex sleep apnea. Complex sleep apnea appears to occur when CPAP and BiPAP treatments trigger previously dormant central sleep apnea. Even though the sleeper uses a BiPAP or CPAP machine to prevent obstructive sleep apnea, the newly developed central sleep apnea causes sleep apnea symptoms. In such cases, it is often beneficial to switch the user from a CPAP machine or BiPAP to an AVS machine.
Disclaimer: The information contained within this article is for informational purposes only, and is not intended to be a substitute in any way for care and treatment by a qualified health professional.
Resources:
Clark, R. (2006). Sleep Apnea, Snoring and Breathing Problems in Sleep.
Wisegeek. (n.d.). What is BiPAP?
CPAP.com. (n.d.). Frequently Asked Questions
Michael McGrath - Michael McGrath began providing web content shortly after finishing his graduate degree in English at the University of Alberta. His broad ...
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