CPAP, Autopap, BiPaP, DME -what are they?

More than you ever wanted to know from someone who is not a doctor and nothing in the health care field at all - just a happy, well treated autopap user....

CPAP stands for "continuous positive air pressure". Plain CPAP machines deliver one straight pressure all the time - a steady pressure to hold the throat open during sleep when the muscles relax.

The word titration means "find the correct dose". In the case of OSA sufferers, we need our machines to deliver the correct dose of air pressure, measured in cm H20 (how much air pressure it takes to raise a column of water that many centimeters.) A person's prescribed pressure is generally the "titrated" pressure a tech decided worked best during a sleep study, to keep the throat open and prevent sleep disordered breathing (SDB) events - mainly apneas and hypopneas.

An AUTOPAP is a "self titrating" CPAP machine. Also called "self adjusting CPAP". An autopap can be set for a range of pressures - a low pressure and a high pressure. For example, if a person's prescribed pressure is 12, the autopap might be set for a range of 7 - 16, giving some leeway on both ends for the machine to read the person's breathing from minute to minute and let the machine choose what pressure actually does the job to keep the throat open. Autopaps preventively keep the throat open. They don't wait for an apnea to happen and then deal with it.

Popular autopaps are:

Puritan Bennett Goodknight 420E auto
Respironics REMstar Auto with C-Flex
ResMed Autoset Spirit

Collapsibility of the throat varies throughout the night, depending on what stage of sleep a person is in and what position they are sleeping in. The throat is most apt to collapse (shut off air) when a person is sleeping on his/her back (supine position) and is in REM (dreaming) sleep. Thus, we don't always need the same steady "titrated" pressure all night.

Bi-level CPAP machines are like a plain CPAP, in that there is always a single pressure set for inhalation (the prescribed pressure.) But there can also be a second (lower) pressure set to give a pressure drop each time the person exhales. A Bi-Level CPAP machine is often the machine prescribed for people who have very weak pulmonary function - weak lungs - COPD, asthma, etc. Bi-level machines can also come with a "timed" feature which will kick the inhalation pressure in again if the patient's brain hasn't sent a signal to "breathe" after a certain amount of time. Failure of the brain to send a signal to breathe is called a "central apnea" as opposed to the much more common "obstructive apnea" or OSA.

Bi-level CPAPS are commonly called Bipap, although "BiPAP" is Respironics' trade name for its bi-level cpap machine. ResMed's bi-level machine is trade-named "VPAP". Calling all bi-level cpaps "bipap" is much like calling all tissues "Kleenex." A trade name that has practically become a generic name through common usage.

C-Flex is not a type of machine. C-Flex is the trade name for a comfort feature on some Respironics' machines. The C-Flex feature drops the pressure on exhalation. It can be set for three different degrees of pressure drop on exhalation, but cannot be set to an absolutely precise "lower pressure" for exhalation the way bi-level machines can be set.

A relatively new machine that combines the best of both worlds, in my opinion, is the Respironics REMstar Auto with C-Flex. It can operate as an autopap, varying the pressure as needed during the night AND at the same time give a drop of pressure for every exhalation. An excellent comfort feature for people who want the advantages of an autopap, but have difficulty breathing out against pressure. Before, those people would have had to choose between "autopap" (to vary the pressure as needed) or "bipap" (to give a drop in pressure every time they breathed out.) Now they can enjoy relief from pressure every time they exhale, yet be using an autopap which often will let them enjoy lower pressure (lower than their titrated pressure) in general through the night. Lower pressures often mean fewer mask leaks and less chance of aerophagia - swallowed air that can cause painful bloating and gas.

One last definition that doesn't have anything to do with describing a machine, but is often confusing to people who are reading apnea message boards for the first time:

DME - stands for "Durable Medical Equipment". In message board shorthand, "DME" refers to the home health care provider - the bricks and mortar store where you can buy medical supplies such as wheelchairs, crutches, cpap machines, cpap masks, etc. Example: "My DME stocks only one brand of cpap."
It can also refer to an employee of the health supplies store. Example: "My DME was really helpful...she let me try on several masks."
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Interesting links about the value of auto-titration at home using an autopap instead of having a formal PSG titration in a sleep clinic:

Link posted by Mikesus:
Powerpoint presentation at a meeting of the American Lung Association of the Central Coast - November 2004 "Not Every Patient Needs To Go To the Sleep Lab" by Barbara Phillips, M.D. MSPH

Barbara Phillips, MD, MSPH, FCCP
Professor, Division of Pulmonary Critical Care and Sleep Medicine
Director of the Samaritan Sleep Center
Department of Internal Medicine
University of KY College of Medicine
Lexington, KY

Link posted by chrisp:
Sleep Review Mag. Nov 2004 "Home-Initiated Auto-nCPAP vs Conventional nCPAP"

Link posted by Mikesus:
American Journal of Respiratory and Critical Care Medicine Vol 167. pp. 716-722, (2003) "Can Patients with Obstructive Sleep Apnea Titrate Their Own Continuous Positive Airway Pressure?"

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Links to posts about autopaps and autotitration - there's much more on this message board, but here's a start!

Feb 19, 2005 subject: "Sleep Doctor" doesn't like autopaps

Feb 08, 2005 subject: Can APAP eliminate apneas?

Jan 26, 2005 subject: Which CPAP Auto to use>

Jan 11, 2005 subject: Bman: Spirit Overnight Indices

Feb 06, 2005 subject: For Rested Gal or Muck

Feb 21, 2005 subject: Remstar Auto - Non-responsive events?

Feb 14, 2005 subject: APAP and leaky masks?

Feb 14, 2005 subject: How do you "snore" with a nasal mask?

Feb 02, 2005 subject: What can you do anyway?

Mar 06, 2005 subject: Powerpoint Presentation Advocating Autopap

Howdy,

These are really helpful. Titrator is currently working up a lot of content for the CPAPopedia - can we scoop some of this and use it in that context?

Johnny

Sure. Scoop away.