(12-29-2012, 06:22 PM)bensonlee Wrote: The events happened between 3 L / min to 12 L / min with most happening at 7.8 to 11 L / min. I was reviewing the graphs and looks like your statement is really true. Every time the pressure drops the count of events are increasing and will drop as soon as the pressure comes back to around 12 / min.
Looks like I will need to discuss this more on with the doc. Seems below 8 is really not helping.
Quote:What is your pressure 95th percentile?
12.0 L / min
Hi bensonlee, welcome to the forum!
I think you are saying that when the max pressure was set to 14 (cm H2O), the 95 percentile pressure was only 12, with most apnea events and hypopnea events happening while the pressure was between 7.8 to 11. If I had these numbers in my sleep report data, I would be tempted to set my minimum pressure to 10 and keep my max pressure at about 14. It is pretty common to set the max pressure about 2 higher than the 95% pressure.
The measurement unit for pressure is centimeters of water (cm H2O). One cm H2O is a really small amount of pressure. For example, it takes about 70 cm H2O to equal just one pound of pressure.
The measurement unit for leak and other air flows is liters per minute (L/min).
To answer an earlier question, your 95 percentile leak of 1.2 L/min is excellent, but even zero would not be too good to be true.
When adjusting the straps on an S9 Autoset, one should always use the Mask Fit feature. But keep in mind that it is easy to tighten the mask straps more than necessary. So, if the straps feel at all uncomfortable because of tightness, one can (while using the Mask Fit feature) see if the straps can be loosened just a little without increasing the Leak. Be sure to keep the strap lengths on the left side and on the right side symmetrical. (Top straps same length as each other, and bottom straps same length as each other).
bensonlee Wrote:The only differences I had today was actually to reduce the max pressure from 14 to 12 because I incorrectly set it the first time. Using SleepyHead, I noticed that on the first night, I had ERP x1, while last night I set it to none.
Could this explain the difference?
Do you mean the pressure was 14 on both 27 Dec and 28 Dec and tonight it will be 12? I would be tempted to leave the max pressure at 14 (especially if you use any EPR) and raise the minimum pressure.
Regarding EPR (exhalation pressure relief), lowering it from 1 to zero is unlikely to make the AHI worse, from 12.2 to 71.1. A more likely explanation would be your sleep position changed. For example, sleeping on one's back can often cause the AHI to be much worse compared to sleeping on one's side, unless one is using an Auto machine which can raise the pressure high enough. There are lots of reasons for AHI to vary from one day to the next, which is why it is recommended to change the pressure settings gradually, leaving things alone for a week or two or longer between each adjustment, paying attention to long term averages and not the night-to-night fluxuations.
When EPR is set to 1, 2 or 3 this is the amount the pressure is lowered during exhalation compared to the normal (higher) pressure used during inhalation. When a respiratory therapist does a "bi-level titration" to find the optimal bi-level pressure settings during an overnight titration study (and I think using EPR is in some ways very similar to using a bi-level machine), the procedure recommended by the american medical association is to (very gradually) raise the CPAP pressure until obstructive apneas are eliminated and then to raise only the IPAP (pressure during inhalation) higher, in order to eliminate sleep disturbances called RERAs (respiratory effort related arousals). The increased pressure during inhalation makes it easier to breath in.
My point is that if using EPR we may need to increase the min and max pressures by the same amount as the EPR. For example, increasing EPR from 0 to 3 would keep the IPAP pressure unchanged but would lower the EPAP pressure by 3. If we want to change EPR to 3 (from zero) without lowering the EPAP pressure we would need to raise the minimum and maximum pressure by 3 as well.
(12-29-2012, 06:22 PM)bensonlee Wrote:
Quote:how many mask events shown on usage (summary graph) and duration of each
27 Dec - 6 events
28 Dec - 3 events
29 Dec - 2 events
Events usually last from 30 minutes to 6 hours.
Not sure what you mean. In the Detailed results section of the ResScan report, ResScan shows apnea events as a red candlestick along with the number of seconds that the breathing was stopped. The candlestick has a red diamond on top if the apnea was an Obstructive Apnea event, or a white diamond on top if ResScan classified the event as a Central Apnea event.
On the Statistics page, what are your CAI (Central Apnea Index), OAI (Obstructive Apnea Index), UAI (Unknown type Apnea Index), HI (Hypopnea Index) and overall AHI for each date? If few of the apneas are classified by ResMed as Central events (in other words, if very little of the AHI is from CAI), then keeping the max pressure at 14 should be OK.