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Resmed S9 Autoset question
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projman65 Offline

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Machine: Resmed S9 Autoset
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Sex: Male
Location: Tampa, Florida

Post: #1
Resmed S9 Autoset question
I woke up at 4:45 AM this morning and couldn't fall back asleep. 10-15 minutes later, I noticed the air pressure being pretty high on my face. I looked over to the screen on the machine, and it showed the pressure at 15.4 (my settings are 10-16).

I am a little puzzled why the pressure was so high, even 10-15 minutes after being awake and breezing normally without having any apneas. Shouldn't it have been 10? the lower end? I was under the impression that the S9 provides pressure as needed, breath by breath. Am I missing something here?

I then decide to use the bathroom...I turn the machine off, unplug myself, use the bathroom, plug myself back, turn the machine on...now the pressure start as normal at 10.

Any ideas?
04-26-2012 01:13 PM
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CHanlon Offline

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Posts: 292
Joined: Mar 2012

Machine: ResMed S9 Autoset
Mask Type: Nasal mask
Mask Make & Model: ResMed Activa LT
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CPAP Pressure: 12 -20
CPAP Software: ResScan SleepyHead

Other Comments: Mirage Activa LT nasal mask

Sex: Male
Location: Ontario, Canada

Post: #2
RE: Resmed S9 Autoset question
It doesn't drop instantly back down to the lowest setting, sort of maintains what it thinks you need. If you pull up last night in ResScan, and look at the detailed info, pressure graph, you'll see how it moves up and down throughout the night, and tails off gradually after each rise.


Since you turned off in between, you should even be able to see that exact point in the graph, you'll see the "session break" in the data.
04-26-2012 01:53 PM
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PaulaO2 Offline
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Machine: S9 Autoset
Mask Type: Full face mask
Mask Make & Model: F&P Simplus
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CPAP Pressure: 14-20
CPAP Software: SleepyHead

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Post: #3
RE: Resmed S9 Autoset question
Your breathing changed when you woke up. The autoset was trying to figure out why. It cannot tell if you are awake or asleep, only that the air pressure is blocked or not.

PaulaO2
Apnea Board Moderator
www.ApneaBoard.com


Breathe deeply and count to zen.

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
04-26-2012 01:54 PM
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projman65 Offline

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Posts: 21
Joined: Apr 2012

Machine: Resmed S9 Autoset
Mask Type: Full face mask
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Humidifier: Resmed 5i
CPAP Pressure: 9-16
CPAP Software: ResScan

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Sex: Male
Location: Tampa, Florida

Post: #4
RE: Resmed S9 Autoset question
(04-26-2012 01:53 PM)CHanlon Wrote:  It doesn't drop instantly back down to the lowest setting, sort of maintains what it thinks you need. If you pull up last night in ResScan, and look at the detailed info, pressure graph, you'll see how it moves up and down throughout the night, and tails off gradually after each rise.


Since you turned off in between, you should even be able to see that exact point in the graph, you'll see the "session break" in the data.

Your explanation makes sense...so I guess it doesn't really adjust the pressure breath to breath.
04-26-2012 02:04 PM
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greatunclebill Offline

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Machine: Respironics System one Auto A-Flex
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Sex: Male
Location: L.A. (Lower Alabama)

Post: #5
RE: Resmed S9 Autoset question
(04-26-2012 02:04 PM)projman65 Wrote:  
(04-26-2012 01:53 PM)CHanlon Wrote:  It doesn't drop instantly back down to the lowest setting, sort of maintains what it thinks you need. If you pull up last night in ResScan, and look at the detailed info, pressure graph, you'll see how it moves up and down throughout the night, and tails off gradually after each rise.


Since you turned off in between, you should even be able to see that exact point in the graph, you'll see the "session break" in the data.

Your explanation makes sense...so I guess it doesn't really adjust the pressure breath to breath.

BINGO!!!! this is why setting a machine, any auto cpap, at 4 - 20 and letting it self adjust is just plain wrong. now you see why people say to go a couple points above and below the cpap number and see where it takes you.
04-26-2012 03:56 PM
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zonk Offline

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Machine: A10 AutoSet
Mask Type: Nasal mask
Mask Make & Model: Activa LT
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CPAP Pressure: 9/13
CPAP Software: ResScan

Other Comments: CPAP since Nov 2010

Sex: Male
Location: Australia

Post: #6
RE: Resmed S9 Autoset question
(04-26-2012 02:04 PM)projman65 Wrote:  so I guess it doesn't really adjust the pressure breath to breath.
AutoSet devices adjust pressure on a breath-by-breath basis to suit patient needs as they change throughout the night.
Source: ResMed
04-28-2012 03:46 PM
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JumpStart Offline

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Posts: 297
Joined: Feb 2012

Machine: ResMed S9 Autoset
Mask Type: Full face mask
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Humidifier: ResMed H5i
CPAP Pressure: 10 - 20 (auto range)
CPAP Software: ResScan SleepyHead

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Location: Houston, Texas

Post: #7
RE: Resmed S9 Autoset question
(04-26-2012 02:04 PM)projman65 Wrote:  [...so I guess it doesn't really adjust the pressure breath to breath.

From ResMed site:

AutoSet devices evaluate flow limitation on a breath-by-breath basis and adjust pressure according to a five-breath average. (emphasis added)

Breathing keeps you alive. And PAP helps keep you breathing!
05-03-2012 03:18 PM
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CHanlon Offline

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Posts: 292
Joined: Mar 2012

Machine: ResMed S9 Autoset
Mask Type: Nasal mask
Mask Make & Model: ResMed Activa LT
Humidifier: ResMed Hi5
CPAP Pressure: 12 -20
CPAP Software: ResScan SleepyHead

Other Comments: Mirage Activa LT nasal mask

Sex: Male
Location: Ontario, Canada

Post: #8
RE: Resmed S9 Autoset question
(05-03-2012 03:18 PM)JumpStart Wrote:  
(04-26-2012 02:04 PM)projman65 Wrote:  [...so I guess it doesn't really adjust the pressure breath to breath.

From ResMed site:

AutoSet devices evaluate flow limitation on a breath-by-breath basis and adjust pressure according to a five-breath average. (emphasis added)

I *knew* I'd seen that somewhere when I was researching them, but of course I couldn't find it when this question came up. That's the detail that explains the entire operation.
05-03-2012 03:25 PM
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JumpStart Offline

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Posts: 297
Joined: Feb 2012

Machine: ResMed S9 Autoset
Mask Type: Full face mask
Mask Make & Model:
Humidifier: ResMed H5i
CPAP Pressure: 10 - 20 (auto range)
CPAP Software: ResScan SleepyHead

Other Comments: ResMed Mirage Quattro

Sex: Male
Location: Houston, Texas

Post: #9
RE: Resmed S9 Autoset question
(05-03-2012 03:25 PM)CHanlon Wrote:  I *knew* I'd seen that somewhere when I was researching them, but of course I couldn't find it when this question came up. That's the detail that explains the entire operation.

From the duration of this thread to the time of my posting, I guess you noted that this info was not exactly on the tip of my tongue, either! :grin:

Breathing keeps you alive. And PAP helps keep you breathing!
05-03-2012 04:59 PM
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zonk Offline

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Posts: 7,908
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Machine: A10 AutoSet
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CPAP Pressure: 9/13
CPAP Software: ResScan

Other Comments: CPAP since Nov 2010

Sex: Male
Location: Australia

Post: #10
RE: Resmed S9 Autoset question
Sleep Review: How does your product respond once a sleep-disordered breathing event is detected?

ResMed:
The AutoSet algorithm is truly a predictive approach allowing proactive treatment of sleep apnea rather than simply reacting with a pressure change after an event has occurred; this is achieved by detailed analysis of the inspiratory flow versus time curve. Flow limitation analysis in the AutoSet algorithm is a complex blend of clinical sleep science and engineering; it provides very small adjustments in pressure, sometimes as little as 0.2 cm H2O at a time to ensure that the patient is not aroused from sleep (as measured by EEG) with such pressure changes. This approach allows AutoSet to preemptively treat many obstructive sleep apnea events before they even occur. When an event does occur that is not possible to prevent by the flow limitation approach, AutoSet will respond reactively as well. ResMed's AutoSet algorithm assesses the severity of the event using a blend of the inputs such as duration of the event severity and frequency of the event over time. The AutoSet algorithm then determines the optimal pressure change solution to treat the event and prevent future events and applies it comfortably with minimal disturbance to the patient's sleep.
AutoSet responds to events based on a five-breath moving average of the inspiratory flow-time curve in order to prevent the device from responding to sporadic breathing events, such as sighs or coughs. Inspiratory flow limitation, or partial airway closure, usually precedes snoring and obstructive hypopnea and apnea events; it is also most often associated with obstructive hypopneas as they occur. AutoSet adjusts in increments as small as 0.2 cm H2O to ensure that pressure increases only as much as is necessary.
For flow limitation, AutoSet calculates the shape of the inspiratory flow-time curve and the value for every breath (using a metric known as the flattening index); however, it responds based on the average value of the most recent five breaths, as described above. Detection of flow limitation enables the device to increase the pressure before obstruction occurs, making treatment preemptive, and thus reducing the number of respiratory events and arousals. The apnea response is determined by the severity of the event and current therapy pressure. Apnea pressure changes are delivered after the event such that the pressure change will not arouse the patient. Snore response is measured using the severity of the vibrations of the snore. A more severe snore will give a larger pressure response, but this proportional response is delivered over the next series of breaths such that the pressure change does not disturb the sleeping patient.
If no further flow limitation, snore, or apneas are detected, therapy is reduced over time toward the minimum pressure prescribed by the physician with a 20-minute time constant. This approach allows the pressure from ResMed's AutoSet algorithm to return to lower pressures for increased patient comfort in the absence of any respiratory events.
http://www.apneaboard.com/forums/Thread-...y-Pressure
05-03-2012 05:45 PM
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