Significant variations in AHI and associated Resp rate

[Ron10]

After several months of frustration attempting to determine the reasons for significant differences in AHI from one day to the next. One consistent factor seems to be associated with numerous and very active resp rate which seems to reach almost impossible rates of breaths per minute, quickly advancing from a baseline of approx 16 to 40-50 (as captured in the following OSCAR screenshot. Is a resp rate with many approaching 50 even possible or would it be reasonable to suspect an issue with my Resmed airsence auto?

https://imgur.com/a/tF3wgaC

Thanks
Ron Mason

[LSAT]

There is no issue with your machine..I don't know where you got your pressure settings from, but the pressures need adjustment..Increase Min to 8 and Max to 20. That should solve your AHI problem.

[palerider]

Also, don't shrink your chart, it's just a fuzzy blur.

[Dog Slobber]

After you've moved your min to 8 wait a week or so, then post another [non-fuzzy] chart to see if your min needs to be raised again.

[rick blaine]

Hi Ron10,

Wrt to an apparent resp rate of 40 to 50, there is such a thing as the 'saw tooth pattern' in breathing. It's a topic which has come up before. You can use the search facility top left to find out more.

As a brief re-statement:

1. In respiratory medicine, there is such a thing as a 'saw-tooth' curve on the spirometer (the machine that shows doctors a person's breathing pattern), and it turns up in about 12 per cent of those with obstructive sleep apnea. It is usually found on the inspiration part of the curve, and medical opinion is: it is of no great consequence.

2. It seems that when confronted with this pattern, the graphical part of the software 'sees' two or three breaths in the time taken for one complete inhalation. The thing to go by is the digital 'Med' (or median) reading in the left-hand column.

3. In any event, resp rate on its own is not all of the story - the tidal volume is just as important. And is it the combination of median resp rate and tidal volume which goes to give the minute ventilation.

The 'normal' resp rate for most people (at rest) is 12-15 per minute. The average tidal volume for a male of average height (and at rest) is 440 mil. Giving a minute vent of 6.60 litres.

Your MV is 6.75 – well within the normal range.