stopped breathing for 30 seconds and pressure didn't change?

[Dave007]

I viewed my sleep data via SleepHead software and noticed a few instances where I stopped breathing for about 30 seconds. I checked pressure during this time and it looked like nothing changed (maybe it went up 1). Shouldn't the pressure go up a lot more to get me to breath?

Obviously something needs to be changed what settings should I tell my doctor to adjust? min pressure...max pressure...EPAP. (he's more clueless than me).

If you look under "Flow rate" You'll see I basically stopped breathing for a bit with no intervention from the machine.

[Wulfman...]

I viewed my sleep data via SleepHead software and noticed a few instances where I stopped breathing for about 30 seconds. I checked pressure during this time and it looked like nothing changed (maybe it went up 1). Shouldn't the pressure go up a lot more to get me to breath?

Obviously something needs to be changed what settings should I tell my doctor to adjust? min pressure...max pressure...EPAP. (he's more clueless than me).

If you look under "Flow rate" You'll see I basically stopped breathing for a bit with no intervention from the machine.

NOPE! XPAP machines typically won't attempt to stop an apnea while it's in progress. They increase pressures on Flow Limitations and Snores, which are believed to be precursors to apneas. Some people don't have those precursor events.
In Bi-Level/Bi-PAP therapy, the EPAP pressure may need to be increased.

Den

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[Pugsy]

It won't respond for a single lone apnea event like that during the middle of the event...it waits till the end of the event like it did in this situation..see the increase in pressure at the end of the event at around 7:33:00?
I am pretty sure that this is the way the algorithm works when dealing with single lone apnea events.
Now if there happens to be a cluster of events happen I think the machine gets more agressive.

[CaptainRaven40]

It won't respond for a single lone apnea event like that during the middle of the event...it waits till the end of the event like it did in this situation..see the increase in pressure at the end of the event at around 7:33:00?
I am pretty sure that this is the way the algorithm works when dealing with single lone apnea events.
Now if there happens to be a cluster of events happen I think the machine gets more agressive.

From what I understand Pugsy has once again hit the information right.

[Wulfman...]

It won't respond for a single lone apnea event like that during the middle of the event...it waits till the end of the event like it did in this situation..see the increase in pressure at the end of the event at around 7:33:00?
I am pretty sure that this is the way the algorithm works when dealing with single lone apnea events.
Now if there happens to be a cluster of events happen I think the machine gets more agressive.

From what I understand Pugsy has once again hit the information right.

It depends on the manufacturer and the algorithms they use in their auto machines.

Here's one from a Respironics machine.

Den

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<P>NR = Non-Responsive Apnea/Hypopnea event</P>


Above 8 cmH2O pressure, the pressure increase for sustained apneas/hypopneas is limited to 3 cmH2O above the pressure setting at the onset of the apnea/hypopnea sequence.
The pressure setting at the onset of the sequence is called the "Onset Pressure."
The pressure 3 cmH2O above the "Onset Pressure" is called the "NRAH Threshold."
"NRAH" is an acronym for "Non-Responsive Apnea/Hypopnea.

An apnea/hypopnea x2 event detected after reaching the NRAH Threshold is considered to be non-responsive.

A special case of Non-Responsive A/H is when the events are hypopneas only, with no apneas.

After seeing two Hypopneas, the algorithm increases the pressure by 1 cmH2O, and the Onset Pressure resets to this new pressure level.

However, the Onset Pressure can not be raised above 12 cmH2O by a sustained string of Hypopnea-only events.
This does not imply that the Onset Pressure value can not be set above 12 cmH2O. It only states that the Onset Pressure can not be <b>RESET</b> above 12 cmH2O due to a string of Hypopnea-only events.
The maximum NRAH Threshold due to a sustained string of Hypopnea-only events will be 3 cmH2O above 12 cmH2O.

When the device encounters a non-responsive apnea or hypopnea, it will decrease pressure by 2 cmH2O and hold the pressure for 15 minutes.
During this 15-minute "NRAH-hold" period, the pressure will be changed only in response to detection of a sequence of vibratory snore events.
The reason for this increase in pressure followed by a decrease in pressure when an apnea/hypopnea is not responsive is to allow the device to respond appropriately to an event that is not treatable by increases in pressure, such as a central apnea.

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[Wulfman...]

Here are some more of the Respironics algorithm.

Den

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REMstar Auto with C-Flex Algorithm Reference Guide

MULTI LEVEL ALGORITHM

• Primary analysis is measuring instances of flow limitation, it utilizes systematic, subtle changes in pressure and assesses the impact of these changes on the patient’s breathing patterns
• Secondary analysis provides back up response to other acute sleep disorder breathing events such as snoring, apnea & hypopnea
¨ These Pro-active changes in pressure and assessment are continually searching for the best possible pressure level for the patient while maintaining Normal sleep


Primary Analysis – Flow Limitation

P therapy Mode: provides extended period of constant pressure at ideal level. This can range from 5-15 minutes depending on where we are in the analysis

P critical Mode: defines pressure level where airway begins to collapse utilizing 0.5cmH20 drop per minute pressure slope + flow limitation trending calculations. Once flow limitation is observed the pressure is increased 1.5 cm in 15 seconds and P therapy is initiated.

P optimum Mode: defines optimal pressure level where no further improvements are noted utilizing 0.5 cm increase per minute pressure slope + flow limitation trending calculations. After responding to an episode of flow limitation the patient enters a 10 minute P therapy period at the end of a P therapy period a P optimum search is initiated. The search is performed to see if there can be any further improvement to the flow signal. The P optimum search consists of a 1.5 cm increase in pressure over a 3 minute period. If after this search there is no improvement the pressure is dropped 1.5 cm and P therapy is resumed. If during the P optimum search there is improvement made to the flow signal then the pressure will be increased .5 cm per minute. Once there is no further improvement to the flow the pressure is dropped .5 cm reinitiating P therapy.


FOUR PARAMETERS USED IN DETERMINING FLOW LIMITATION

1. Roundness, deviation from sinusoid with same rate and peak
2. Flatness, deviation from middle mean flow Middle is from 20% to 80% of inspiration
3. Peak Flow, peak inspiratory flow
4. Shape patterns
¨ These parameters are monitored simultaneously
¨ Long term trending (minutes) and short term trending (last 4 breaths) calculations are performed and compared

KEY POINTS

• This flow limitation analysis will cycle continuously throughout the night
• Utilizes “statistically significant” changes approaching 10% change from the baseline flow signal
• Basic premise of Pcrit & Popt searches is to evaluate the profile of the patient flow waveform for improvement or degradation


SECONDARY ANALYSIS / SAFETY NET

Snoring
• 3 snores detected (one minute period)
• Triggers pressure change 1cmH20 / 15sec
• Reinitializes P therapy state of operation Apnea / Hypopnea
• Two respiratory events (Apnea/Hypopnea) occurring within a 3 min period
• Triggers pressure change 1 cmH20/15 sec
• Reinitializes P therapy state of operation
• Maintain peak flow MOVING average to determine % reduction in flow
 Apnea 80% reduction in flow / 10 sec duration
 Hypopnea 50%reduction in flow / 10 sec duration
Only 2 snores or 1 Apnea are required to trigger a pressure change if detected in the Pcrit cycle



NON RESPONSIVE APNEA/HYOPNEA EVENT OR CENTRAL PREDICTOR

• NR Events differentiated from obstructive apneas & hypopneas
• Above 8 cm., pressure increases for a sequence of sustained apneas/hypopneas will be limited to a 3 cm increase
• If detection continues a 2 cm decrease in pressure and a 15 minute hold period is engaged
• In theory, we are assuming central events {goal: not to significantly increase pressure when this condition is detected
• Logged as NR on SmartCard
¨ If snoring occurs, pressure increase +1 cmH20, Ptherapy state re-initiated


ELEVATED LEAK LEVELS
• Large Leak Levels occur @ > 2 times the average mask exhalation port leak(At 20cm normal leak is 40 large leak is 90)
• Considered to be in “Large Leak” if threshold exceeded for greater than 1.5 minutes
• Large Leak threshold increases as pressure increases
• “Large Leak” cleared when the leak level falls below threshold for more than 1.5 minutes
• Drops pressure 1 cm every two minutes until big leak condition is cleared
¨ Large leak indicator is a great tool to identify interface issues – logged in Encore
¨ Robust leak threshold will allow for proper titration even under less then optimal condition


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[Pugsy]

His profile shows ASV Resmed machine and the quick response that is seen goes more in line with how ASV machines respond to centrals than the typical slower response from apap machines.
ResMed's respond faster than Respironics though...no matter if it is apap or ASV.
The ResMed ASV doesn't differentiate between OAs and centrals on their reports. Instead they lump both OAs and centrals into the "apnea" category...hence SH report above calling it a UA.
I don't know enough about the ResMed algorithm on the ASV models to know if they work all that differently though I suspect there is at least some difference.

The pressure was already relatively high at the time of the event so there wasn't a lot of room to go to 25 (which it did) so I don't know if that was normal response for OA or the quick burst for a central.
I am also not well versed in reading the flow rate graphs to tell if it was OA or central....so I don't know for sure what it was.

At any rate what is seen doesn't seem unusual based on what little I know about how ASV works and since the overall events graph is really quite decent I don't know that anything needs to be done in this situation with random events of any kind. Not enough of them to cause a problem.

[Wulfman...]

Another one from the ResMed A10 manual. Maybe a little simplistic in defining the algorithm.

Also acknowledging I read Pugsy's post regarding ASV.

Den

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ResMed A10

AutoSet mode

The treatment pressure required by the patient may vary due to changes in sleep state, body
position and airway resistance. In AutoSet mode, the device provides only that amount of pressure
required to maintain upper airway patency.
The device analyzes the state of the patient’s upper airway on a breath-by-breath basis and delivers
pressure within the allowed range according to the degree of obstruction. The AutoSet algorithm
adjusts treatment pressure as a function of three parameters: inspiratory flow limitation, snore, and
apnea.

Normal airway
When the patient is breathing normally, the inspiratory flow measured by the device as a function of
time shows a typically rounded curve for each breath.

Flow limitation
As the upper airway begins to collapse, the shape of the inspiratory flow-time curve changes. The
AirSense 10 recognizes and treats traditional as well as less common flow-limited breath wave
forms.

Snore
Snoring is sound generated by vibrations of the walls of the upper airway. It is often preceded by
flow limitation or a partial obstruction of the airway.

Apnea
The enhanced AutoSet algorithm detects both obstructive and central apneas. If an apnea occurs,
the device responds appropriately.

Obstructive apnea
An obstructive apnea is when the upper airway becomes severely limited or completely obstructed.
AutoSet generally prevents obstructive apneas from occurring by responding to flow limitation and
snoring. If an obstructive apnea occurs, the device will respond by increasing pressure.

Central apnea
During a central apnea, the airway will remain open, but there is no flow. When a central apnea is
detected, the device responds appropriately by not increasing pressure.

AutoSet for Her mode
AutoSet for Her mode is based on key aspects of ResMed’s AutoSet algorithm and delivers
therapeutic responses tailored to the characteristics of female OSA patients.
The AutoSet for Her is similar to ResMed’s AutoSet algorithm with the following modifications:
· Reduced rate of pressure increments designed to help prevent arousals.
· Slower pressure decays.
· Treats apneas up to 12 cm H2O and continues to respond to flow limitation and snore up to 20 cm H2O.
· Minimum pressure (Min. Pressure) that adjusts according to the frequency of apneas:
If two apneas occur within a minute, the pressure reached in response to the second apnea will
become the new minimum treatment pressure until the next treatment session.

Patients who use AutoSet for Her will still get the benefits of ResMed's AutoSet technology
including improved sensitivity to flow-limitation and Central Sleep Apnoea Detection with Forced
Oscillation Technique.

CPAP mode
In CPAP mode, a fixed pressure is delivered—with optional Expiratory Pressure Relief (EPR™).

Reporting
The AirSense 10 reports Respiratory Effort Related Arousals (RERA), and detects Central Sleep
Apnea (CSA) and Cheyne-Stokes Respiration (CSR). The summary and detailed data of these
parameters are available to view on ResMed's patient compliance software (data availability
depends on device mode and parameter measured).
Central sleep apnea detection
Available in all modes on the AirSense 10 AutoSet, AirSense 10 AutoSet for Her and the AirSense 10 Elite.

The device detects both obstructive and central sleep apneas (CSA). CSA detection uses the Forced
Oscillation Technique (FOT) to determine the state of the patient’s airway during an apnea. When an
apnea has been detected, small oscillations in pressure (1 cm H2O peak-to-peak at 4 Hz) are added
to the current device pressure. The CSA detection algorithm uses the resulting flow and pressure
(determined at the mask) to measure the airway patency.

Cheyne-Stokes respiration detection
Available in all modes on the AirSense 10 AutoSet, AirSense 10 AutoSet for Her and the AirSense 10 Elite.
Cheyne-Stokes respiration (CSR) is a form of sleep-disordered breathing characterized by a periodic
waxing and waning of respiration. The waxing periods (hyperpneas, typically 40 seconds in length)
can include large gasping breaths that tend to arouse the patient while the waning periods
(hypopneas or apneas, typically 20 seconds in length) cause blood oxygen desaturations.
The following example shows a typical CSR period.

The AirSense 10 device reports the time during therapy in which it detected breathing patterns
indicative of CSR. It analyzes the patient's respiratory flow for apnea/hypopnea events, calculates
the time between these events, and characterizes the shape of breathing between them.
Respiratory effort related arousals reporting
Respiratory Effort Related Arousals (RERA) reporting is available on the AirSense 10 AutoSet for Her
in all modes.
RERAs are periods of increasing respiratory effort which are terminated by an arousal. Increasing
respiratory effort will be seen as airflow limitation.These flow-based RERA events are logged and
stored as summary and/or detailed data and can then be viewed in one of ResMed's patient
management systems.

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[Dave007]

Thanks for the info. Is there an alarm I can set so that after not breathing for 10 seconds I hear a beep of some kind? 30 seconds seems to be a while to go without breathing...I'd rather get an alarm at 10 second mark than go 30 seconds.

[JDS74]

Your profile indicates two different machines. Which one is the one in question?
If it is the Aircurve ASV, there is a cpap mode. Any chance that is selected? Your chart looks just like what mine did when I was using a Respironics AutoBiPap and experienced extended central apnea events.