CPAP Detect Centrals?

I know a cpap machine can't differentiate between central and obstructive events, but will it register an apnea event for either type? Or if you have you have a central event, it just doesn't register anything? In other words, if I have a central event will it show up as an apnea on the reports just like an obstructive event shows up as an apnea?

I always thought yes, but in reading something today, it started me wondering.

Pam

WearyOne wrote:I know a cpap machine can't differentiate between central and obstructive events, but will it register an apnea event for either type? Or if you have you have a central event, it just doesn't register anything? In other words, if I have a central event will it show up as an apnea on the reports just like an obstructive event shows up as an apnea?

I always thought yes, but in reading something today, it started me wondering.

Pam

Pam,

I have the new Sandman and it registers central apneas as CA (cardiac oscillations) and central hypopneas as cnt H, plus snores, runs, and your obs A and obs H. I think the PB420E does, too, and Respironics, I don't know about any others that do.

Others on here can give you more info than I can. I only know about the Sandman from experience.

Anne

WearyOne wrote:I know a cpap machine can't differentiate between central and obstructive events, but will it register an apnea event for either type? Or if you have you have a central event, it just doesn't register anything? In other words, if I have a central event will it show up as an apnea on the reports just like an obstructive event shows up as an apnea?

I always thought yes, but in reading something today, it started me wondering.

Pam

Hi Pam.

Apparently, the Puritan Bennett 420 E (and Covidien Sandman Auto) machines have some Cardiac Oscillation detection circuitry and firmware that is supposed to be better at determining Central Apneas.
However, in our REMstars, lack of breathing (for about 10 sec. or more) is defined as an Apnea and they can't tell which is which, but they will be noted and the approximate amount of time recorded.

Den

Thanks, Den. That's what I thought. Right now, I'm just concerned with knowing that if I have a central event (of >10 sec) that at least an apnea will be noted on the report (not that I know which type it is, of course). My AHI is always less than 4, and most of those are hypopneas with average time in apneas around 6 seconds (although I have longer ones up to 20 second about twice a month). Just didn't want to think I was doing so great with the low numbers and then find out centrals weren't going to show up as anything. Not sleeping well the past few weeks with no real discernible reason why, at least on the reports. Could be stress, though, as I'm waking up a lot, etc. Just trying to figure it out on my own since I can't afford another sleep study right now. (Vent rate is good, too.) Snoring could be an issue, since it's been worse over the past four or five months since I've gained a little weight, but I only started having the sleeping problems in the last couple of weeks. Just need to lose the weight and see if that helps (well "if,"--I know it will--LOL).

Pam

Weary one,

The best way of determining if someone is having a central vs an obstruction is by measuring effort to breathe. In the lab that is easy, they put an air flow detector near you nose & an abdominal effort sensor on you plus a few other probes that added together say this person has no airflow and is making no effort to breathe.

Having a machine that can monitor Cardiac Oscillations is a step in the right direction. Just how well it can detect and register a genuine CA is an interesting question.

Good topic

Cheers DSM

Here is a link to report on Cardiac Osc in relation to OSA
http://www.physionet.org/physiotools/apdet/apdet.shtml

An extract from the intro (my reading of this is, that if you can determine that a zero flow is an obstruction based on the patter of Cardiac Oscillations then it seems likely you can use the pattern to differentiate an obstrction from a no effort zero flow) ...

Obstructive sleep apnea (OSA), the periodic cessation of breathing during sleep due to intermittent airway obstruction, is a frequently undiagnosed condition affecting millions of individuals worldwide, and is associated with increased morbidity and mortality. Current technology for the diagnosis of sleep apnea requires overnight monitoring of the patient in a specially equipped sleep laboratory. Because of the expense and inconvenience of standard polysomnographic recording, less costly and more easily implemented techniques for detection of high-risk subjects would be desirable.

Our approach is based on the finding that OSA frequently alters healthy heart rate dynamics. In normal healthy respiration, heart rate dynamics exhibit a broadband, inverse power law spectral distribution [1]. In contrast, during periods of prolonged OSA, the heart rate typically shows cyclic increases and decreases associated with the apneic phase and the resumption of breathing [2]. These cycles which tend to oscillate at a frequency of between 0.01 and 0.04 Hz, are a distinctive feature of OSA not found during normal respiration. We hypothesized that we could detect and quantify these periods of high-density OSA by the fully automated identification of these oscillatory dynamics in the RR interbeat interval series.

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This para sort of sumarizes the findings ...

By using the Hilbert transformation of the RR interval time series, we have shown that it is possible to detect prolonged episodes of high-density OSA from single-lead electrocardiograms with a high degree of accuracy, discriminating both subjects with OSA and determining the onset and offset of prolonged high-density OSA. In addition, this technique is able to quantify both the amplitude of OSA heart rate oscillations and their frequencies. Improvements in filtering techniques and parameter adjustments may further increase the efficacy of this technique.

Although this technique is ineffective in detecting the small number of sleep apnea subjects who do not exhibit the oscillatory heart rate dynamics commonly found in prolonged OSA, it may prove to be a cost-effective and convenient means to screen for OSA and to monitor response to therapy. It may also be useful in detecting and quantifying other pathologic heart rate oscillations, such as those found in Cheyne-Stokes syndrome or periodic breathing at high altitude [6], as well as fetal distress syndromes [7].

Hmmm,

What goes around comes around

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DSM