What is a normal tidal volume and Peak flow

General Discussion on any topic relating to CPAP and/or Sleep Apnea.
Strapparatus

Re: What is a normal tidal volume and Peak flow

Post by Strapparatus » Wed Sep 03, 2008 4:57 pm

Peak flow is a PFT measurement is not false, although peak flow is based on a height, age, gender basis.
FYI. For an 80 kg with excellent lungs = 800 mls. per vt / x rate of 8 per minute sedated on propofol (diprivan)
is not an excessive tidal volume. This equation is and always has been used in critical care patients unless
they have kyphoscoliosis, a restrictive lung disease, pneumothorax, etc. Stiff, non-compliant lungs would require less tidal volume. True, 10-15 mls/kg is on the high end for adult patients on mechanical ventilators. Its when a patient develops
ARDS (Adult Respiratory Distress Syndrome) that things get trickier as PEAK inspiratory Pressure rises you have to protect the alveolar terminal bronchus. I apologize for referencing the mechanical ventilator numbers and will try to avoid these to this audience. Normal tidal volume is about 500 mls per breath but that is shallow. Normal rate is 12-20 breaths per minute or an average of 6 lpm - 10 lpm. This is all dependent on PCO2 and whether the central brain is impaired.
In regards to peak flow, in our ER, we do peak flows with a simple forced expiration on asthmatics. The numbers are generally between 350 liters per second to 600 liters per second. Obviously an asthmatic is going to have reduced measurements. Someone 5'4" should be able to exhale about 400 liters per second. Treatments are indicated if that number is less than 75% of expected "ideal". Below 50% "ideal" that person would need to see a physician or start on their nebulizer or inhaler.

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Snoredog
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Re: Hold Your Horses...

Post by Snoredog » Wed Sep 03, 2008 6:12 pm

Banned wrote: As I understand SAG, Tidal Volume is a range between 5-8 ml/kg of ideal body weight, as in BMI (Body Mass Index). If you base your calculations on http://www.freedieting.com/tools/ideal_body_weight.htm, you should get an idea where you stand.

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Now why did ya have to go post that??

I now have to lose a pound, guess that means I have to ride 10 miles tonight at a fast pace instead of my usual 5 mi

At least it is cooling down from today's 102F.
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StillAnotherGuest
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That Would Be Pretty Windy...

Post by StillAnotherGuest » Thu Sep 04, 2008 3:39 am

Strapparatus wrote:In regards to peak flow, in our ER, we do peak flows with a simple forced expiration on asthmatics. The numbers are generally between 350 liters per second to 600 liters per second. Obviously an asthmatic is going to have reduced measurements. Someone 5'4" should be able to exhale about 400 liters per second.
That value is measured in liters/minute. Gustav's Peak Flow is 400 liters per second.

SAG
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Re: What is a normal tidal volume and Peak flow

Post by StillAnotherGuest » Thu Sep 04, 2008 4:04 am

Strapparatus wrote:For an 80 kg with excellent lungs = 800 mls. per vt / x rate of 8 per minute sedated on propofol (diprivan)
is not an excessive tidal volume.
1200 ml certainly would be. The 10 - 15 ml/kg becomes increasingly inappropriate as weight increases (i.e., ideal body weight is not used).
Strapparatus wrote:Stiff, non-compliant lungs would require less tidal volume. True, 10-15 mls/kg is on the high end for adult patients on mechanical ventilators. Its when a patient develops ARDS (Adult Respiratory Distress Syndrome) that things get trickier...
Interestingly, that recommended tidal volume value is 6 ml/kg.
Strapparatus wrote:Its when a patient develops ARDS (Adult Respiratory Distress Syndrome) that things get trickier as PEAK inspiratory Pressure rises you have to protect the alveolar terminal bronchus. I apologize for referencing the mechanical ventilator numbers and will try to avoid these to this audience.
Actually, the concept of "Protective Lung Strategies" might prove quite interesting to the group.

SAG
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dsm
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Re: What is a normal tidal volume and Peak flow

Post by dsm » Thu Sep 04, 2008 4:33 pm

StillAnotherGuest wrote:
Strapparatus wrote:
<snip>
Strapparatus wrote:Its when a patient develops ARDS (Adult Respiratory Distress Syndrome) that things get trickier as PEAK inspiratory Pressure rises you have to protect the alveolar terminal bronchus. I apologize for referencing the mechanical ventilator numbers and will try to avoid these to this audience.
Actually, the concept of "Protective Lung Strategies" might prove quite interesting to the group.

SAG
Vote me in too for any discussion on "Protective Lung Strategies" - the tpic is not one that comes up often and like SAG am sure many of us would like to learn what we can even if it gets a bit medically technical.

If we need a starting theme I would like to understand what the occasional chest pain is that many of us experience when starting xPAP then on occasions over time. I am not referring to any heart problems but I keep reading such comments posts by others and have experienced this myself. For me the most recent such event was a couple of weeks back - woke up 2 nights in a row with mild chest pain right across the chest - for myself I have done astress ECG & have good clean bill of health heart wise so am concluding this is to do with lungs. The data from my machine didn't show any unusual activity for the 2 nights.

What I would like to understand is if this is a common occurrence among cpappers ? - is it just from sleeping in an odd position ? - is it a casual side effect from pressure ventilation ? (for me it has happened on all modes xPAP - Cpap, Apap, Bipap, SV).

Tks

DSM
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Re: What is a normal tidal volume and Peak flow

Post by wlo2008 » Thu Sep 04, 2008 4:43 pm

DSM, I also have experienced this pain as well. When I first started it and once in a while with the Bipap. Like you my ticker is fine. they already looked into that just to make sure. Sometimes I wonder if it from swallowing some air and a gas bubble getting suck. My aunt told me she experiences the same thing. Her doc told her with her Fibromyalgia, he thinks that the scare tissue on her chest with sometimes the volume of air pressing on her chest, will make some pain at times. If she is having a bad pain day then she feels it.

I am not sure this is the case with others.

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Re: What is a normal tidal volume and Peak flow

Post by Slinky » Thu Sep 04, 2008 4:49 pm

Ya jinxed me, DSM! Cut it out!

For the VERY FIRST TIME I woke up w/a weird feeling, discomfort, in the chest this morning. AND some carotidynia. Supposedly carotidynia is caused by pressure on the carotid artery. But I sleep on my back all night so don't have the SLIGHTEST idea where any pressure could have come from. I, too, have had all clear stress tests (recent 2 year done just a couple of months ago). It was NOT AT ALL like heartburn or a gas bubble or lung congestion causing a tight feeling in the chest. Altho in a way slightyly tight and slighty bruised might be an apt description. More like restricted maybe?

Too bad I still haven't figured out YET how to post some of my data from my Resmed VPAP Auto and S8 ResLink 'cause w/COPD I'd be a prime candidate for a "Protective Lung Strategies" discussion thread. Post data from a "normal" set of lungs and my crappy ole COPD lungs for comparison. Heck, SAG, maybe I oughtta just snail-mail a data card to you! Have you got ResScan 3.4 or 3.5?

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Re: What is a normal tidal volume and Peak flow

Post by Snoredog » Thu Sep 04, 2008 4:52 pm

don't tell me this discussion is about to turn towards.....


........PEEPS!!
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Re: What is a normal tidal volume and Peak flow

Post by Slinky » Thu Sep 04, 2008 5:00 pm

Awwww, SnoreDog, you're so cute, a little ole Pink Peep! But, owwww! I don't think the world is ready or able to survive if there really are THREE of you!!!

Darn! They took my "sticking my tongue out at you" Smiley away!!!! Foul!! Foul!

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dsm
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Re: What is a normal tidal volume and Peak flow

Post by dsm » Thu Sep 04, 2008 6:21 pm

Slinky,

He really means this type of PEEP

positive end-expiratory pressure

DSM
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Re: What is a normal tidal volume and Peak flow

Post by Slinky » Thu Sep 04, 2008 7:28 pm

Oh. I kinda liked looking at those little Pink Peeps. "Ain't" never heard of no "positive end-expiratory pressure", DSM. Thanks.

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StillAnotherGuest
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Hey, Strapavarius!

Post by StillAnotherGuest » Sat Sep 06, 2008 4:11 am

Boy, threads disappear fast with this new format!

However, I'm glad that the spell-checker is functional again.

Now if only there was a format checker that would correct all my "{" to "[" then I'd be all set. (I don't know why I do that, but it's like half the time! Just like "patinet" and "respiratroy". But I digest. Hmmm. That don't look right either.)
Strapparatus wrote:Accuracy is not as important as precision.
I doubt seriously that all of the formulas have been factored in logarithms for the equipment you use in the home.
For example, loss of volume due to heated humidification. Loss of volume due to Pouseille's law, etc. This is 1st year Respiratory Therapy information.
LOL! Well, unfortunately, I am not a 1st year Respiratory Therapy student! (However, if I was, I would prefer to be called a "1st Year Respiratory Care Practitioner").

However if
1st year Respiratory Therapy book wrote:Poiseuille's law takes into account the physical dimensions of the tube (radius and length) and the nature of the fluid moving through the tube. Poiseuille's equation states that frictional resistance to flow is directly related to viscosity of the fluid and length of the tube and indirectly related to the fourth power of tube radius (r4)
and nobody ever changes tube radius, length (OK, hardly ever on that one), and density of the gas (unless they decide to send in helium), then how does
Strapparatus wrote:Pouseille's law
apply?

Further, since
Strapparatus wrote:Pouseille's law
relates to laminar flow, is it not ineffective in truly assessing the Sum of Flows as they relate to CPAP Users? As more and more stuff is placed in the circuit (humidifiers, bacterial filters, aromatherapy diffusers, pom-poms, and a wide variety of interfaces), the effect of turbulent flow becomes increasingly important as pressure loss down the circuit will occur.

The concept of turbulence was mercilessly hammered to death in the discussion of the K1 - K2 concept in

I Thought K2 Was A Mountain?

Definitely not gonna be a beach day today.

SAG
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Aromatherapy may help CPAP compliance. Lavender, Mandarin, Chamomile, and Sweet Marjoram aid in relaxation and sleep. Nature's Gift has these and a blend of all four called SleepEase.

cicero28374

Re: What is a normal tidal volume and Peak flow

Post by cicero28374 » Tue Sep 30, 2008 1:08 pm

Mt ResMed adapt SV states that my VT is "213-668" for a week and "204-718" for the month.
What is this telling me. My BMI is 21, I'm an old fart w/severe PH and sleep disorders.
Thanks in advice for a statement I can understand.
God have mercy on us all
Cicero

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dsm
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Re: What is a normal tidal volume and Peak flow

Post by dsm » Tue Sep 30, 2008 6:23 pm

cicero28374 wrote:Mt ResMed adapt SV states that my VT is "213-668" for a week and "204-718" for the month.
What is this telling me. My BMI is 21, I'm an old fart w/severe PH and sleep disorders.
Thanks in advice for a statement I can understand.
God have mercy on us all
Cicero
Have posted some suggestions in your main thread

Cheers

DSM
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StillAnotherGuest
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A Loose End...

Post by StillAnotherGuest » Wed Oct 01, 2008 4:07 am

In re: normal tidal volume:
SAG wrote:Resting tidal volume is more in the range of 5 - 7 ml/kg (maybe 8 ml/kg if you subscribe to the AVAPS approach
Confusion was created by The Other Poster as he submitted a value of "10-15 mls/kg", but that value only relates to calculating Mechanical Ventilator Tidal Volume Breaths for patients with Respiratory Failure. Controlled (Unassisted) Mechanical Ventilator Breaths need to be twice as large because they are half as efficient, creating V/Q Mismatch (ventilation does not match perfusion, or, more simply, exchange of air does not match the blood flow in the lung. Neither of those is uniform throughout the lung). A Forced Mechanical Ventilator Breath takes the Path of Least Resistance, which, unfortunately, is the one that doesn't have the blood flow in it.

The Other Poster should have read his "First Year Respiratory Therapy Book" and been as attentive as this student in her Hunger For Knowledge:

Image

Yaaaahhhhooooooooooooooooooo!!!!!!!

(Although it appears this mini-student thinks the magazine is "The Reader's Digest" and is taking that to the extreme.)
cicero28374-Gueted wrote:Thanks in advice for a statement I can understand
Spontaneous Patient Breaths = Good
Forced Machine Breaths = Less Good

SAG
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Aromatherapy may help CPAP compliance. Lavender, Mandarin, Chamomile, and Sweet Marjoram aid in relaxation and sleep. Nature's Gift has these and a blend of all four called SleepEase.