Questions about flow rate, pressure and AHI

[BByou]

Hi, I am very new to the Apnea Board and breathing treatment. This is my first post :-).

For a quick intro, I started to feel shortness of breadth when I slept at night a few months ago, and sleeping on a wedge pillow made it somehow better. However I often woke up feeling very tired and sometimes with headache. I also started to experience shortness of breath on exertion during the day. I had a pulmonary function test and saw a pulmonologist, he ordered me a bipap machine (ResMed AirCurve 10 ST-A) after further tests and clinical exams. I've been using the machine at night since Sept 10th. It does help me to sleep better during the night. 

I've been reading the forum postings to learn more about breathing and sleep, and have been monitoring my sleep stats using SleepyHead. As I am very new to all this I am still trying to get my head around a few things, and have some questions -

• My AHI has been high every day, around 19 ~ 24. I don't know if I have apnea problem to start with. Should I be concerned? I do feel tired in the day.
  
• The spont trig is 30% for last night. It started as 44% and has been gradually dropping. The spont cyc number has been stable on the other hand, at around 56%. Does this mean I need to adjust the machine setting?
  
• Sometimes I feel like I am waiting for the next breath to kick in (if that makes sense)? I tried to make meaning of my flow rate wave forms. Do you think there's indication of restriction?
  

I have attached my SleepyHead charts for your reference. Any insight and feedback is appreciated! Given that I've only been using the machine for 1.5 weeks, it can also be that I just need to give it more time for it to work.

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Thanks for the help!

[Sleeprider]

Thanks for including so much valuable information in your charts. Before answering your questions, I need to know if you have any diagnosis for central or complex apnea, or if your problems are related to a neuromuscular, or other hypoventilation condition. I suspect you are on the wrong machine. Please describe any respiratory conditions you are aware of, and let us know if you have had diagnostic and/or titration sleep studies.

Your ST is set for EPAP 4.0 and IPAP 11.0. Your respiration rate appears to be 12.0, but I don't know what backup rate is set on your Aircurve 10 ST-A. It appears you are in ST mode. In addition to the question above regarding diagnosis, please minimize the monthly calendar in future charts by clicking the triangle in the date-line above the calendar, and turn off the pie chart in Sleepyhead menu File/Preferences/Appearance, and uncheck the pie-chart.

Your close up of flow rate shows that the pressure support of 7.0 is helping trigger minimal flow-limited breaths. It is clear you need more pressure support (higher IPAP pressure) to fill those breaths. The problem is that some people respond to pressure support with and have treatment onset central apnea that requires a different approach. I suspect that you might suffer from central apnea and need a machine known as ASV which provides variable pressure support from breath to breath and can ensure you take a full breath when you don't spontaneously breath (central apnea), or enough support to provide a full breath during hypopnea, and unlike the ST will adjust EPAP higher to guard against obstructive apnea (UA). Let's learn more about you so we can help you get on your way to the right therapy.

[BByou]

Hi Sleeprider, 

Thanks for the fast response. My current problem is neuromuscular related and my diaphragm muscle is getting weak. So I was prescribed a bipap machine to help me to breath at night. I was never diagnosed of sleep apnea. I've always been a light sleeper, not able to sleep through the night with good rest. But it's more due to my busy mind and not able to fully relax. I never went to the doctor for sleep problem and didn't have diagnostic sleep study.
 
Regarding setting, I am using the ST mode and the backup rate is set at 12. In case if it's helpful here are my other settings: Ti Max 3.3s, Ti Min 1.0s, rise time 300ms, trigger low, cycle med. My pressure setting is IPAP 13 and EPAP 4. My respiratory therapist raised IPAP by 2 (from 11) 2 days ago after seeing my sleep report for the last week. 

Thanks for the insight on ASV and pressure support adjustment. I will look into it to learn more, and may come back if I have more questions. Thanks!

Best,
BB

[Sleeprider]

If you do have a neuromuscular disorder, the solution to the severe flow-limited breaths is higher pressure support (increasing IPAP). Your doctor will agree when he sees the data you posted above.

You can increase IPAP to 12 and observe results. We will continue to increase IPAP until hypopnea is less than 5 per hour. The UA events may require an increase in EPAP. These are easy changes to make and we can help you enter the clinician menu. If you advise your doctor of these results I’m confident he will recommend the same. I am not suggesting you go around your doctor but you should let him know of this problem sooner than later. It is still important that these settings be challenged in a titration test because the high pressure support may be triggering central apnea heretofore undiagnosed.

[BByou]

Thanks, Sleeprider. My current IPAP setting is 13. I will observe how it goes and come back to update. I have a follow-up appointment with my pulmonologist in mid-October and will share with him my sleep report and ask him to adjust setting based on the results. Thanks for the help.