Mask seal vs leak

Hello,
I’ve just started using a cpap of being diagnosed with OSA with an ahi of 28, and an rdi of 30. I’ve been using the cpap for the last 4 days and one thing that is confusing me is every night the mask seal is a green smiley face, but my leak is around 26-30L/min. From what I’ve been reading this higher than the Resmed operational limit, so I’m not understanding why it still says the mask seal is good. As well the AHI is pretty low, I’m getting around 1.3 per night. Still feel sleep and tired though.

36Chambers wrote: ↑

Sun Apr 23, 2023 1:36 pm

Hello,
I’ve just started using a cpap of being diagnosed with OSA with an ahi of 28, and an rdi of 30. I’ve been using the cpap for the last 4 days and one thing that is confusing me is every night the mask seal is a green smiley face, but my leak is around 26-30L/min. From what I’ve been reading this higher than the Resmed operational limit, so I’m not understanding why it still says the mask seal is good.

It's statistics.

The leak rate number that shows up in the sleep report is the so-called 95% leak rate. If your 95% leak rate is 30 L/min, that means that for 95% of the night, your leaks were at or BELOW a rate of 30 L/min. And your leaks were AT or ABOVE 30 L/min for 5% of the night.

Mr. Green Smiley face shows up whenever your 70% leak rate is LESS THAN 24 L/min.

So the fact that you see Mr. Green Smiley in the morning, but the 95% leak rate is 30 L/min means all of the following things are true:

1) Your leaks were LESS than 24 L/min for at least 70% of the night. So your leak rate is under Resmed's definition of a Large Leak for at least 70% of the night.

2) Your largest leaks were at least 30 L/min and you had leaks that were AT or ABOVE 30 L/min for at least 5% of the night.

3) For 25% of the night, we don't really know whether your leaks were UNDER 24 L/min or whether your leak rate was between 24 L/min and 30 L/min. The only way to tell whether your leaks were ABOVE 24 L/min for more than 5% of the night is to download the data in Oscar and look at it.

You might want to look at my blog entry Average, Median, 95% numbers: A guide to those who don't remember their introductory stats to make more sense out of why Mr. Green Smiley can show up while your 95% leak rate can be (well) over 24 L/min.