Inspiration and Expiration Time

[MrIvanDrago]

Quick Question. I have searched the board and have a simple question. What is a good Insp.Time vs. Exp.Time (Ratio) with CPAP therapy? Just trying to get an idea.

[Crimson Nape]

According to Google:

Inverse Ratio Ventilation - StatPearls - NCBI Bookshelf
National Institutes of Health (.gov)  Apr 6, 2023

A typical I:E ratio for most situations would be 1:2. If we apply this ratio to the patient above, the 6-second breath cycle will break down to 2 seconds of inspiration and 4 seconds of expiration. Changing the I:E ratio to 1:3 will result in 1.5 seconds of inspiration and 4.5 seconds of expiration.

- Red

[MrIvanDrago]

According to Google:

Inverse Ratio Ventilation - StatPearls - NCBI Bookshelf
National Institutes of Health (.gov)  Apr 6, 2023

- Red

I saw that searching with Google, however, I rarely ever see OSCAR reports on this board with folks within that ratio.

[Crimson Nape]

I just checked my averages for last night, and it equates to 1:1.63.

- Red

[MrIvanDrago]

I just checked my averages for last night, and it equates to 1:1.63.

- Red

Ok thanks, that's around where I am as well.

[THEVGE]

I am more like 1:1,1 no matter the settings on my CPAP. Don't feel like having an issue with a stable respiratory rate of between 13-15 (measurements by smart watch). My therapy is not working well yet, waiting for BiPAP to solve flow limitations (my AHI has always been < 1).

Interesting question I wanted to ask as well. Following.

[Sleeprider]

You cannot necessarily rely on the Oscar reported inspiratory and expiratory median times. These are actually reported by the machine in question and is invariably inaccurate in all Philips machines and may be inaccurate in Resmed devices, especially where expiratory flow approaches zero and/or in the presence of cardiogenic oscillation. I often ask members for zoomed images of the flow rate so I can confirm or refute the reported statistics. Most of the time in healthy individuals, the respiratory ratio falls into a normal range from 1:1 to 1:3, and I have observed the majority of I:E ratios are close to one to 1.5. Inspiration time that is confirmed to be longer than expiration time is normally attributable to flow limitation, and abnormally long expiration is often asthma or COPD.

Historic trivia: Originally Sleepyhead displayed an I:E ratio, but it was incorrectly calculated as Texpiration/Tinspirationx100 and produced a number like 65.0, which was off by a factor of 100, meaning inspiration was .65 the time of expiration. It was decided back in February 2019 that Oscar should not report the I:E ratio due to the inaccurate reporting of inspiration and expiration times by the machines, general confusion on the part of Oscar users and the fact the legacy calculation was simply wrong. Ultimately, Oscar is a "Reporter" of information provided by the devices and today, Oscar does not report the I:E ratio for this reason, and it has not been reported since Sleepyhead 1.1.0. Here is a legacy image of Sleepyhead:

[THEVGE]

Thanks for your explanation Sleeprider!

[MrIvanDrago]

Sorry for all the questions, but reading and looking at others OSCAR data in past posts, what is ideal inspiration and expiratory times. 

For example, I have seen some charts where inspiration time is something like 2.3s and expiratory time is 1.2s.

Then others, like mine, where inspiration time is 1.3s and expiratory time is 2.1s or something like that. Does it matter? Do the machines get this correct? Thanks for all this board does!

[Dormeo]

This seems to be an OK web site, and there's information there:

https://respelearning.scot/topic-1-anato...-breathing

Keep in mind that the machine counts the pause between breaths as exhalation time.

When I used a ResMed Airsense 10 Autoset, I got weird ratios of inhalation to exhalation (inhalation longer than exhalation). With the VAuto, all is well. It seems that the Airsense 10 got confused by the cardioballistic artifacts that show up as little oscillations between breaths on my flow rate graphs. For whatever reason, the VAuto isn't confused by the CB artifacts.