Tidal Volume Yep I searched but

[Ghost1958]

What I found didnt really tell me anything.

What I really want to find out if anyone knows is using sleepyhead software
here is what I have and if I need to worry about it.

TV runs median from 340 to 450 no set pattern but never below that and never above that as a median number.

Respiratory rate ranges 15 to 18 median which from what I can find is normal range.

The kicker is the last four nights my flow chart range per breath that always ran +26 -26 went first down to 23 both top and bottom and last nite 22 both top and bottom. Nothing else changed. AHI of .7
Min pressure 9 max 18 set. But pressure runs median at 10 and never goes over 13 max.

Is that flow chart range to narrow and is that tidal volume to low??

Im 6 2 245 lbs. And totally lost where it comes to converting regular numbers to metric numbers LOL. Thanks.

[DeepBreathing]

G'day Ghost

As a point of comparison, I'm rather short and lightly built (apart from the spare tyre around my belly ) - about 5'7" and 155 lb if my conversion to American units is correct. My median tidal volume is 540 and 95% is 780 mL. Respiration rate median is 10 and 95% is 13. This is all over 60 days.

So as a skinny little guy I breathe slower and deeper than you as a big heavy guy. From some quick browsing, it seems the "typical" at-rest Tv for a healthy 70kg male (eg me) is about 500 mL, so I think I'm more-or-less in the normal part of the curve. Whether your faster, shallower breathing is outside the norm for a person of your size, I don't know. Maybe somebody with medical knowledge can help us out.

And totally lost where it comes to converting regular numbers to metric numbers LOL.

Luckily we have been metric in Australia for many decades, though a lot of people still tend to use the old units colloquially. What I like about the metric system is the interchangeability of units. For example (and for practical purposes) 1 cubic centimetre (cc) = 1 millilitre (mL). 1000 mL = 1 litre, which can be displayed as a cube 10 cm on a side. 1 cc of water weighs 1 gram. 1 litre of water weighs one kilogram, and one cubic metre of water contains 1000 litres and weighs 1 tonne. All so beautifully easy and self-consistent.

[vsheline]

TV runs median from 340 to 450 no set pattern but never below that and never above that as a median number.

Respiratory rate ranges 15 to 18 median which from what I can find is normal range.

The kicker is the last four nights my flow chart range per breath that always ran +26 -26 went first down to 23 both top and bottom and last nite 22 both top and bottom. Nothing else changed. AHI of .7
Min pressure 9 max 18 set. But pressure runs median at 10 and never goes over 13 max.

Is that flow chart range to narrow and is that tidal volume to low??

Im 6 2 245 lbs.

Hi Ghost1958,

Our Tidal Volume is the area inside the Flow waveform. Long term, inside the Flow waveform the average inhale volume (average positive area) must equal the average exhale volume (average negative area).

You may be interested in these posts:
http://www.apneaboard.com/forums/Thread-...2#pid84492
http://www.apneaboard.com/forums/Thread-...2#pid84532

To calculate your height in cm, convert your height into inches (6'2" = 74") and multiply by 2.54, which is the number of cm per inch. Result is 188 cm for height.

As a male, your IDEAL weight is 82.2 kg, as obtained from the ideal weight and tidal volume calculator mentioned in the post for which the link is provided above. (In the formula below we must use ideal weight, not actual weight.)

Multiply your ideal weight by something between .005 to .007, which yields something between 0.411 Liter to 0.575 Liter.

So, for a male with your height, approximately 411mL to 575mL is the expected range for Tidal Volume.

Not sure, but I think this may assume 15 breaths per minute, in which case perhaps this calculation can be adjusted by 15/18 if your respiration rate is 18, yielding an expected tidal volume between 343mL to 480mL.

Keep in mind that the tidal volume measured by our CPAP machine is an estimate. On my machine, the amount of Leak has a strong effect on the estimated Flow and the estimated Tidal Volume. The more Leak, the smaller the estimated Tidal Volume. I doubt my actual Tidal Volume changes very much; I think the estimated Tidal Volume gets less accurate (gets under-reported) as the Leak increases.

[Ghost1958]

G'day Ghost

As a point of comparison, I'm rather short and lightly built (apart from the spare tyre around my belly ) - about 5'7" and 155 lb if my conversion to American units is correct. My median tidal volume is 540 and 95% is 780 mL. Respiration rate median is 10 and 95% is 13. This is all over 60 days.

So as a skinny little guy I breathe slower and deeper than you as a big heavy guy. From some quick browsing, it seems the "typical" at-rest Tv for a healthy 70kg male (eg me) is about 500 mL, so I think I'm more-or-less in the normal part of the curve. Whether your faster, shallower breathing is outside the norm for a person of your size, I don't know. Maybe somebody with medical knowledge can help us out.

And totally lost where it comes to converting regular numbers to metric numbers LOL.

Luckily we have been metric in Australia for many decades, though a lot of people still tend to use the old units colloquially. What I like about the metric system is the interchangeability of units. For example (and for practical purposes) 1 cubic centimetre (cc) = 1 millilitre (mL). 1000 mL = 1 litre, which can be displayed as a cube 10 cm on a side. 1 cc of water weighs 1 gram. 1 litre of water weighs one kilogram, and one cubic metre of water contains 1000 litres and weighs 1 tonne. All so beautifully easy and self-consistent.

Thanks for the reply. What is throwing me is everything I read is like 500 mL As in mililiters. Which I would think would be considerably more than liters while Sleepyhead shows quote amount of air displaced per min L/m which I read as liters per min.

Am I reading SH wrong or just stupid

While sleepyhead shows L/m which I read as liters per min.

[PaytonA]

Ghost,

Another for comparison. Statistics from about 3 months. I am 5'10" and weigh around 300 lb.

Tidal Volume

Median 500
95% 720
Max 1100

Respiratory Rate

Median 18
95% 20
Max 23


Best Regards,

PaytonA

[DeepBreathing]

The peak flow on the graph (say 25 or 30 L/min) is the maximum rate at which air is passing through, but it's only at that maximum for a very brief period (maybe less than a second). For most of the breathing cycle, the flow rate is much less. Also the tidal volume is the amount displaced per breath, so if my breathing is 10 bpm and my Tv is 500 mL, then the total air displaced per minute would be 10 x 500 mL = 5000 mL = 5 litres.

[vsheline]

What is throwing me is everything I read is like 500 mL As in mililiters. Which I would think would be considerably more than liters while Sleepyhead shows quote amount of air displaced per min L/m which I read as liters per min.

Am I reading SH wrong or just stupid

While sleepyhead shows L/m which I read as liters per min.

Hi Ghost1958,

I agree with everything DeepBreathing wrote.

The Flow waveform is the Rate (in Liters per minute) at which air is entering (positive Flow) or exiting (negative Flow) our airway/lungs. Our Tidal Volume is the average area inside the Flow waveform during one inhale time period or during one exhale time period.

Minute Ventilation is the total volume inhaled or exhaled in one minute. Tidal Volume is the total volume inhaled or exhaled in one breath. Respiration Rate is the total breaths in one minute.

If you want to calculate Tidal Volume because your machine reports Minute Ventilation and Respiration Rate but not Tidal Volume, to get the Tidal Volume simply divide the Minute Ventilation by the Respiration Rate (and multiply by 1000 if converting from Liters into milliLiters).

[Ghost1958]

What is throwing me is everything I read is like 500 mL As in mililiters. Which I would think would be considerably more than liters while Sleepyhead shows quote amount of air displaced per min L/m which I read as liters per min.

Am I reading SH wrong or just stupid

While sleepyhead shows L/m which I read as liters per min.

Hi Ghost1958,

I agree with everything DeepBreathing wrote.

The Flow waveform is the Rate (in Liters per minute) at which air is entering (positive Flow) or exiting (negative Flow) our airway/lungs. Our Tidal Volume is the average area inside the Flow waveform during one inhale time period or during one exhale time period.

Minute Ventilation is the total volume inhaled or exhaled in one minute. Tidal Volume is the total volume inhaled or exhaled in one breath. Respiration Rate is the total breaths in one minute.

If you want to calculate Tidal Volume because your machine reports Minute Ventilation and Respiration Rate but not Tidal Volume, to get the Tidal Volume simply divide the Minute Ventilation by the Respiration Rate (and multiply by 1000 if converting from Liters into milliLiters).

Ok now here we go LOL. I knew the waveform is half in half out and needs to be the same inhale exhale. What I noticed was where the top of the wave usually reached 26 to and also 26 bottom in the past week and half its went to 23 on both ends and now 22 both ends.

Im looking at the reported Tidal volume in the test report on the left side of the screen on SLeepy head where it gives respiration rate, min vol, tidal volume etc

The tidal volume reading is in L/m which the little pop up screen says means liters per min. But when everyone speaks of tidal volume they speak in ml.

So from what I gather im at the moment running a bit low in the tidal volume area??? The machine is what is reporting the tidal volume in the area of the screen on the left that Im looking at along with the min vent values and all the rest. Just wondering if those numbers are low. From the posts giving me some comparison it looks like maybe they they are on the tidal volume. But its counting L/m where everyone seems to be saying ml which confuses me.

As far as me being able to mathematically figure all that out I couldnt but the machine reports it just in L/m vs ml.

Not freaking out over it or anything just was a change I had not seen before that is holding for about a week now and wondered about it.

I feel fine, my leaks are fine, AHI is.7 consistently runs 1 or less on 8 to nine hours.

Was just a change I sorta wanted to check with you good folks on as I havent really posed many questions just read posts and searched.
Figured I ask to see if the software was going wonky or Im going wonky

[DeepBreathing]

Figured I ask to see if the software was going wonky or Im going wonky ont-know: :Laugh-a-lot:

Errr.. it's the software that's wonky. You're right, the popup flags in SH (ver 0.9.6) do indeed say the tidal volume is in L/min. That's wrong - it's actually in mL. I think that's just a simple mistake.

I feel fine, my leaks are fine, AHI is.7 consistently runs 1 or less on 8 to nine hours.

'nuff said! Keep up the good work, lie back and relax.

[vsheline]

Im looking at the reported Tidal volume in the test report on the left side of the screen on SLeepy head where it gives respiration rate, min vol, tidal volume etc

The tidal volume reading is in L/m which the little pop up screen says means liters per min. But when everyone speaks of tidal volume they speak in ml.

So from what I gather im at the moment running a bit low in the tidal volume area??? The machine is what is reporting the tidal volume in the area of the screen on the left that Im looking at along with the min vent values and all the rest. Just wondering if those numbers are low. From the posts giving me some comparison it looks like maybe they they are on the tidal volume. But its counting L/m where everyone seems to be saying ml which confuses me.

As far as me being able to mathematically figure all that out I couldn't but the machine reports it just in L/m vs ml.

If SleepyHead has units of L/m for Tidal Volume, that would be a SleepyHead mistake, not a mistake made by the machine.

The Tidal Volume is a volume (in Liters, for example), not a rate (not in Liters per minute).

The "Flow" is a rate, the volume of air inhaled or exhaled per unit of time.

The Flow is not averaged across several breaths like the Tidal Volume is. The instantaneous Tidal Volume (what would be plotted as a waveform) is averaged over a sliding window of several breaths, like maybe 5 or 6 breaths. If only a single breath is very shallow, surrounded by normal breaths, the Flow waveform would show the shallow breath clearly much smaller than the surrounding normal breaths, but the Tidal Volume waveform might not show much change (because several nearby normal breaths would be included in the average).