(07-05-2014, 01:29 PM)robysue Wrote: In your case it looks like all that's happening is a whole bunch of H's are getting through. And the temptation is to simply assume all the Hs are obstructive in nature. (And in that case, a bit more pressure would be the thing to try.) But there are also some Unknown Apneas being scored and those UAs are scored when the leak is NOT in or close to Large Leak territory. And you say your diagnosis included some central apneas. Those two things taken together hint at the possibility that some of the current problem may be central in nature rather than obstructive. And if there is a central problem, more pressure might make things worse instead of better.
Hi niallm, welcome to the forum!
You have an "ST" type of machine, which can be operated in ST mode and synchronize itself to your natural breathing rate but, if you fail to take a breath, is also able to step in with a backup breathing rate to help keep you breathing. It should be able to help treat your central events as long as the Pressure Support (PS) is high enough. The PS is the pressure boost your machine adds to help with inhalation. It is the pressure difference between EPAP and IPAP.
For example, when I am making too little or no effort to breathe, my ASV machine will increase PS to do for me most (or, if necessary, all) of the work of breathing.
I normally need PS to be around 4, but PS may need to automatically raise itself to 6 or 8 if it needs to do for me most of the work of breathing.
My ASV machine would NOT be able to treat my hypopneas and apneas if its Max PS setting or if its Max IPAP setting were to be too low and were to prevent it from being able to automatically raise PS high enough to treat my hypopneas and apneas.
In your case, IF THE HYPOPNEA CLUSTERS ARE CENTRAL in type (for example, if these are NOT accompanied by Flow Limitation), to treat your hypopneas the machine may need to use larger PS (by raising IPAP without changing EPAP).
Or, in your case, IF THE HYPOPNEA CLUSTERS ARE OBSTRUCTIVE in type (for example, if these ARE accompanied by Flow Limitation), to treat your hypopneas the machine may need to use larger EPAP without changing PS (by increasing IPAP by the same amount that EPAP is raised).
Or maybe you would benefit from increasing both EPAP and PS (by increasing IPAP more than however much EPAP is raised).
As robysue has pointed out, it is best to consult your doctor after emailing him your sleep reports.
However, SleepyHead is beta software and still has some bugs, and ResScan is bug free and will work with your ResMed machine, so I suggest it would be best to send your doctor ResScan reports (which he would likely be more familiar with, anyway) rather than SH reports.
I've now investigated what types of settings your machine has. Your machine does not have settings for Max PS or Max IPAP because EPAP and IPAP are fixed settings on the ResMed VPAP ST, only manually adjustable.
So if the difference between EPAP and IPAP is too low, the machine will not be able to adequately treat central events on its own without at least some effort on your part. But, at the same time, if the difference between EPAP and IPAP is too large this might increase your tendency to have central events (even though the larger PS also helps to better treat the central events when they do occur). Likewise, increasing EPAP or IPAP or both may increase the likelihood of central events occurring.
Also, if PS is too large for too long, this could cause hyperventilation, which can be very unhealthy, causing too much oxygen in the blood, increasing oxidation and increasing the number of free radicals in the blood, leading to atherosclerosis and accelerated aging and other health problems, such as interfering with prescription medications. (A recording oximeter could be used to occasionally monitor SpO2, the saturation percentage of oxygen, overnight and verify that oxygen levels are, on average, in the mid-to-low 90's, which would be adequate without being too high.)
I suppose an ST machine works best when the "backup rate" change to IPAP triggers our own effort to breathe, interrupting the central event at its start, resulting in a normal strength inhalation. But in your case, during a central event, perhaps the machine's "backup rate" change to IPAP is not succeeding in triggering your breathing effort, and your machine's PS of 4 is too low to keep you adequately ventilated without some breathing effort on your part. Perhaps an ASV machine is needed?
Carefully slow and gradual optimization will likely be needed, since you may have a tendency for central events to occur (since you have been prescribed an ST machine which is usually not prescribed unless central events were predominant).
Is your machine set in "ST" therapy mode, or is it in plain "S" mode without a backup rate?
What is the percentage of Spontaneously Triggered Breaths (the percentage of breaths which you yourself started)?
What is the percentage of Machine Triggered Breaths (the percentage of breaths which the machine started because you had failed to initiate inhalation)?
What are the settings for Ti Min and for Ti Max (the minimum and maximum time limits allowed for inhalation)?
Does ResScan report how much Flow Limitation is occurring, and, if it does, is Flow Limitation occurring when the hypopnea clusters are occurring?
If your hypopnea clusters are not accompanied by Flow Limitation then I would think it likely that IPAP needs to be increased. In other words, if FL is not occurring then I think these are central events which can be helped by higher PS without changing EPAP. The higher PS will help directly to ventilate you at least a little more both before and during a central event, and the larger change to IPAP pressure may also help to better trigger your own breathing effort. (But in some patients a higher IPAP might also increase their tendency to have central events.)
If your hypopnea clusters are accompanied by Flow Limitation then I would think it likely that both EPAP and IPAP need to be increased by the same amount. In other words, if FL is occurring then I think these are obstructive events which can be helped by higher EPAP without changing PS. (But in some patients the higher EPAP and IPAP might also increase their tendency to have central events.)
But it is best to consult doctor before making changes. (Especially since some new condition may have started in April which may need to be diagnosed and treated.)