Help me understand individual breaths

[Setj]

Please help me, a newbie, understand this part of a SleepyHead chart.

1. Why is the flow always negative?

2. Is the shape of the curves normal? (Seems to be a "hitch" on the inhale?)

This cut of the chart is typical when I am sleeping well and breathing calmly.

Thanks!

[Pugsy]

1....SleepyHead bug...mine is showing all above 0 and I know that isn't right either.

2...See if the information here explains things a bit.
http://www.resmed.com/us/assets/documen ... er_eng.pdf

[jaybeem]

I also have a hitch on inhale.

I have never found an explanation. The Resmed .pdf does not show this.

[kaiasgram]

2. Is the shape of the curves normal? (Seems to be a "hitch" on the inhale?)

The "hitch" looks like a very slight sawtooth pattern -- like a teensy weensy wannabe snore:

According to the ResMed guide, if you're in APAP mode you might expect to see a slight increase in pressure corresponding to the sawtooth lines. Is your pressure riding along the top of your pressure range when your curves look like that?

I rarely see a lovely, smooth hilltop shape to my flow line but I'm pretty sure now that normal encompasses some less-than-smooth waves too. Most of the time my waves look like the "flow limited airway" picture except that the funky little peak is always on the right side of the hilltop rather than the left. And my pressure doesn't seem to want to bother increasing for that, even though it could. I don't know why.

[Sludge]

I also have a "hitch" on inhale.

I have never found an explanation. The Resmed .pdf does not show this.

If I understand what you're calling a hitch, you really need to know exactly where -0- is (which will delineate inspiration from expiration).

That said, I believe your -0- is at



Consequently, they are occurring during expiration, and an (the) explanation of the "hitches" are that they are ballistocardiographic artifact (heartbeat pulsations picked up by the pressure sensor).

[Setj]

Consequently, they are occurring during expiration, and an (the) explanation of the "hitches" are that they are ballistocardiographic artifact (heartbeat pulsations picked up by the pressure sensor).

Thanks for the education.

Here is a segment using ResScan where the placement of the 'X' axis appears to be correct.

It looks like the ballistocardiographic artifacts are occurring on exhalation. Maybe there are also a couple of small ones on inspiration (see top flat part of curves).

[Sir NoddinOff]

A very qood question and very good replies... I learn something every day on this forum. I have the same hitch as my exhale cycle begins its turnaround at max negative pressure and heads upwards towards the IPAP trigger point. I'll experiment tonight by raising my EPAPmin from 4.0 to 5.0 and see if that smooths things out. Exhaling against some pressure has never bothered me much since started out with a legacy PR M-series leaf blower! Anyway, I've often wondered about that hitch and now I know!

[MitzyG]

I checked a section of my flow at the same level of detail as yours, during a time when I didn't have an event and mine looks like yours. If lots of people have the same pattern during a non-event moment, I suspect this is somewhat "normal".

[Setj]

If lots of people have the same pattern during a non-event moment, I suspect this is somewhat "normal".

I think we need to see the graph of people who have no sleep apnea and are not using CPAP. This exists somewhere I imagine.

[Rick007]

Here is a segment using ResScan where the placement of the 'X' axis appears to be correct.

It looks like the ballistocardiographic artifacts are occurring on exhalation. Maybe there are also a couple of small ones on inspiration (see top flat part of curves).

Setj, I noticed that the peaks of your waveform appear somewhat flattened, compared to the waveform posted by Jaybeam. His peaks appear more parabolic in shape.

How does your flow limitation graph look. My breathing waveform is also flattened on the peaks and my Flow Limitation graph is quite bumpy. The 95% Flow Limitation value averages .15 on SleepyHead

[Rick007]

The mouth must open to get a comfortable, rhythmic breathing pattern. I believe the airway is just too darn narrow and it is not in the nose.

I thought is was pretty normal to breathe through the mouth during any activity that increases your pulse rate. But then I am far from being an athlete. Besides the part of the airway that is held open by xPAP pressure is beyond where the nasal passages meet with the mouth. So when you mouth breathe the air is going past that same point in the neck.

Does anyone have an idea what a good healthy FL value is?

I don't really know. Everyone here comments on their AHI numbers, but I haven't seen anyone post their actual FL numbers, so let me be the first.

I have been on CPAP since September 2013. On November 1, I started recording several of the parameters in an Excel spreadsheet. By doing this I am able to determine long term averages. I can also see the effect of any changes I make in pressure, EPR settings, etc, etc.

I began CPAPing with a pressure setting of 7.6 cmH20 , and then changed to 10 cmH20 on January 31 2014. Here are the average readings that I obtained. It should be noted that these are the readings obtained from SleepyHead. I have seen Rescan give different values, just as you have already seen in the zero crossing points.

My median Flow Limitations at 7.6 was 0, the 95% value was .15 and the max value was .31.

My median Flow Limitations at 10 was 0, the 95% value was .05 and the max value was .18

I only have 5 readings at the new pressure, but there seems to be a definite improvement in the FL numbers. I have also noticed that my AHI value has remain unchanged , but my CA index has dropped. I would like to continue at 10 cmH20 for at least 2 weeks before I make any declarations about an improvement.

[jaybeem]

If I understand what you're calling a hitch, you really need to know exactly where -0- is (which will delineate inspiration from expiration).

Almost all below zero. ???

[Rick007]

Almost all below zero. ???

SleepyHead does not show the same "0" crossing as Rescan. Even the total swing is about 70 on Rescan and about 90 on SleepyHead. At least the shapes are similar. Here are my personal waveform as shown on both programs.

[Sludge]

Almost all below zero. ???

SleepyHead does not show the same "0" crossing as Rescan.

It would appear that Sleepyhead subtracts "Intentional Leak", which, in ResScan, is already accounted for.

[Sludge]

BTW, an interesting discussion of FL in ResScan is

viewtopic.php?f=1&t=61287