Is there a standrad for Oxygen Desat Events.

[dataq1]

In an article from Sleep Science https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8889990/ they give a clear criterion for identification of a desat event:

ODI refers to the average number of desaturation episodes occurring per hour, where desaturation episodes are defined as a decrease in the mean oxygen saturation of ≥3% (over the last 120 seconds) that lasts for at least 10 seconds.

 
However, here is a Oxygen Saturation plot where the "event" of 3% is really questionable. Yes, the oxygen saturation dropped a total of 3 units, however when compared the previous or baseline readings isn't even close to a 3 unit drop for 10 seconds  
[img][/img]
SO, My question is: Is there a standard method for identifying a  3 or 4 unit desaturation; particularly is there a baseline that has to be taken into consideration?

[Gideon]

In the lab a 3 or 4% Desat is required to formally asgn an apneic event, in addition to the 10 second and amt of restriction rules. The amount depends on who is looking at the results. Typically the Desats are not considered on a CPAP because they do not monitor oxygen levels.

With the tools we have we typically look at sat levels and cumulative duration to indicate what is bad.

A single desat is not bad, ever. There is debate over the critical numbers to look at so we look at what Medicare uses and many insurances use, that is 5+ minutes at or below 88% sat for the nightly period may allow for supplemental oxygen. Some use 90%. Lows, even very low lows, only mean to look deeper.

[dataq1]

Specifically my most direct question would be, in the above graph of Oxygen Saturation versus time (@ one observation per sec) would the indicated Desat (between 160 and 180 sec) be really judged as a 3 % desat?

Then more generally, is there any accepted criteria that addresses the question.... 3 unit drop from what ?

[Gideon]

That is a drop from the previous Sat level.