tniuqs CPAP spin-off thread

[mobey]

Hope you don't mind, but I believe this topic deserves its own thread.

So a couple of questions fer fun

Does the application of CPAP increase or decrease WOB ?

Increases to begin with. OKOK, let me explain. Lets say you are a Pulm Edema pt. (fictitious numbers) You are currently using 60% energy to move air in and out of your wet lungs.

Apply NIPPV (CPAP) you now use 68%.

Once the CPAP starts working and clears out some fluid, your oxygenation improves, and WOB decreases since you are only actively working to breathe against/with the NIPPV but the fluid is gone. Alveoli have been re-recruited and you have more surface area for gas exchange, so your resp rate can decrease.... and hey.... you can get some sleep!

What is true threshold PEEP ?

Don't understand the question

Can CPAP be maintained with a BVM a flow diverter with a spring and ball gauge ?

Hell yes.... although I don't know to what measurement. Anytime you "add on" to the exhaust valve of a BVM you are going to add CPAP (or is that PEEP...??? ... Shit, I WAS on a roll). Anywhoo... Think about it this way; blow through a straw. Now, take that same straw and put a 90 degree bend in it, and extend it. Same thing with a BVM

What is average autopeep on a know COPD patient ?

Should FiO2 of 1.0 be used on a COPD patient ?

Trick question..... okay, kinda

Big question, are they C02 retainers?

Secondary question, are we having an emergency respiratory crisis today?

Secondary secondary question: Should anyone have an Fi02 of 1.0 put on?

What is the statistical incidences of a COPD patient that is also CHF ?

I don't know a number, but I bet it is high.

COPD leading to Pulmonary htn. Pulmonary htn leading to hypertrophic cardiomyopathy. BANG: COPD'er with CHF

Can auto peep be clinically measured ?

For that matter what is auto peep ?

Should auto PEEP be matched or exceeded.

Hang on... gotta phone a friend on this one... where is his number?

Name 3 complication with the application of CPAP.

Anxiety attack due to claustrophobia causing hyperventilation.

Decrease in BP

All the same problems as with IPPV (Barotrauma including pneumothorax, interstital/sub-q emphysema)

Thats all I got right now

[tniuqs]

Ok I'm in, except the quotations brackets part may be confusing, going to tru something different to respond appropriately.

PEEP = Positive End Expiratory Pressures.

CPAP = Continuous Positive Airway Pressure.

Whats the difference ? really ?

Q; Does the application of CPAP increase or decrease WOB ?

Increases to begin with. OK OK, let me explain. Lets say you are a Pulm Edema pt. (fictitious numbers) You are currently using 60% energy to move air in and out of your wet lungs. Apply NIPPV (CPAP) you now use 68%.

Yes fictious numbers would be correct, but the concept is more or less correct Normal breathing in energy consumption 5% of caloric intake per day, in Extremus up to 125 % caloric intake per day (just eye balling metabolic rates because we do not want to go there !!!

Once the CPAP starts working and clears out some fluid, your oxygenation improves, and WOB decreases since you are only actively working to breathe against/with the NIPPV but the fluid is gone. Alveoli have been re-recruited and you have more surface area for gas exchange, so your resp rate can decrease.... and hey.... you can get some sleep!

Nice try: Part 1 not bad, Part 2 hmmmm ok ... improved V/Q match and an increase in FRC and directly out of coles notes in AHS protocols, but I don't understand the "fluid is gone part" gone where and how do requite more alveoli ... start a draught ? Care to try again ? Unfortunately it that does clearly explain why there "could" be a decrease in WOB as some "believe" in CPAP.

Question: So could CPAP actually increase the workload by the right side of heart and hence more of an oxygen demand consumption ?

HOPEFULLY A BETTER EXPLANATION: When NOT in extremus or distress as in normal breathing and during inspiration the WOB is generated by the diaphragm as this is primarily muscle used. (This of course will increases WOB when in extremus) and we all know exhalation is passive in Normal Breathing .. (than GOD because we would have to suck the Air out in CPR ... perhaps that will become new 2015 standards ? Back on topic less sillyness ... Sooo WHEN in extremus "forced exhalation" comes into play as is used as the body needs to move more volumes O2 in, CO2 out, lets call that Minute Volume (frequency x tidal volume = MV) now because we don't have time to wait around to exhale and need another breath (with just the elastic recoil of the chest and gravity) To accomplish this more rapid a respiratory rate the body requires accessory muscle's, purse lip breathing is the body's attempt to generate PEEP (ps auto PEEP is different) but the pursed lips and forced exhalation against this restricting mechanism. The forced exhalation breath out through a straw as you stated, is a great example. NOW if you don't believe me, that just CPAP alone doesnt increase WOB, dont trust me ... just go put a real CPAP on @ 10 cmh2O and then if you still don't believe, me go walk on a treadmill, you will get the picture.

THIS WHY I STRONGLY ADVOCATE BI LEVEL SUPPORT for one thing better quality machine and will not have loss of PEEP ! In lay terms it is a PUSH opon inspiration instead of a gasping on CPAP as there is no volume or pressure support, as this offsets the WOB of the MAJOR muscle of respiration the diaphragm.

Question back: Name 3 accessory muscle groups used in "forced" exhalation, 4 if you want 100%.

What is true threshold PEEP ?

Threshold PEEP is when oxygen transport did not correlate with respiratory mechanics or FRC. Setting an appropriate positive end-expiratory pressure (PEEP) value is determined by respiratory mechanics, gas exchange and oxygen transport. As these variables may be optimal at different PEEP values, a unique PEEP value may not exist which satisfies both the demands of minimizing mechanical stress and optimizing oxygen transport.

<Whew edit late entry, after a coffee>

I should have asked can you determine threshold PEEP, NO but better yet can you even MAINTAIN a constant PEEP value with average O2 equipment on ambulances.

So when a patients Measured Minute Volume it must exceeded by a factor of 4 minimum, that is called a true High Flow System btw.<edit delete I:E ratios nonsense and say 1:4 is acceptable. So when one is breathing at 10 liters per minute, 10 lpm is extremis (normal MVs are average 3.5 to 5.5 lpm). Upon rapid inspiration and quite easily one can achieve 40 liters per minute, a patient can out breath or suck back for lack of fully functioning brain cell's at this juncture. ON ICU ventilators 120 lpm for flow rates are achievable ... that's to match the demands of a thoroughbred at a full gallop, if you catch my drift.

So in order to maintain PEEP The machine/ device whether it be a CPAP device BiPAP or a Ventilator or even a BVM with PEEP Gauge, once again inspiratory flow must exceed the MV x 4 so that the end pressure is not lost, to zero. If you do not a device that can exceed the positive pressure during inspiration then "demand exceeds supply" (for the economists out there) then one cannot assure loss of so ask yourself when looking at any device is this capable of even accurately measuring end exhalation pressures or is it just set somehow with flows and magic theory's ? Because if it is not and no way that you can measure, therefore "you may" or "may not' be maintaining PEEP.

Q:Can CPAP be maintained with a BVM a flow diverter with a spring and ball gauge ?

Hell yes.... although I don't know to what measurement. Anytime you "add on" to the exhaust valve of a BVM you are going to add CPAP (or is that PEEP...??? ... Shit, I WAS on a roll). Anywhoo... Think about it this way; blow through a straw. Now, take that same straw and put a 90 degree bend in it, and extend it. Same thing with a BVM

Hell NO! Its not accurate, you can't measure it (unless you have a gauge in line and very unlikely) and its just its a cheezy spring ball called a flow restrictor, not a flux capacitor. So if you have no air flow OUT of the patient it will equalizes to zero especially true in low Minute Volumes. One MUST have true threshold PEEP to maintain, Question A BIGGY: What is the maximum flow rate you can achieve out of the wall ? And are you exceeding paietnts inspiration demand and is the I:E ratio short enough for the patient to drop go to zero ? ps on a BVM a little trick of the trade .. look at the duck valve if it looks distorted and push out end expiration and still looks like an "outy" before you squeeze the bag again you are most likely maintaining the "set" dialed number.

Q:What is average autopeep on a know COPD patient ?

What no guess ? - 5 for not trying

This depends on the study one quotes from 12 to 14 cmh2O to measure clinically at bedside there is a way, pause the breath, turn set PEEP off the ventilator, occlude the inspitatory limb of the circuit, watch the little gauge and kinda guess .... or just hit measure auto PEEP on the plastic brain of the state of the art ICU ventilator. I include both this in my explanation because there is much controversy, I will trust the Puritian Bennet 640 or Evita. The Point being in most EMS applications of PEEP your not even close to matching the patients auto PEEP and this is the goal in an Asthmatic or COPD that to equilibrate and relieve CO2 gas trapping, goggle the term pendelluft.

Q:Should FiO2 of 1.0 be used on a COPD patient ?

NOT for very long, for any patient in fact due O2 toxicity, oxygen absorption atelectasis increase incidents of ARDS.

Trick question..... okay, kinda

If they are not Saturating above 88% and truly Hypoxic, well you can not kill dead ... Yes use 1.0 FiO2.

Big question, are they C02 retainers?

Gotcha trick question, not a issue and all Paramedics get hung up with this, first off how would you know they are CO2 retainers ... guess or they just look like it COPD ? Or Perhaps do an ABG at bedside to find a PaO2 of 50, PaCO2 of 50, and Ph of 7.40 ? as that is the ONLY way.

Secondary question, are we having an emergency respiratory crisis today?

Ok didnt see that I read and answer one line at a time, you got me.

Secondary secondary question: Should anyone have an Fi02 of 1.0 put on?

Dang caught me again ... your getting sneeky Mobster !

WOW how lucky for me second to last post from Gumby ... EBM studies on COPD patients in OZ !

http://www.emtcity.com/index.php/topic/16879-when-will-o2-truly-help/page__st__60__gopid__252055#entry252055

or

http://www.ncbi.nlm.nih.gov/pubmed/20959284

Q:What is the statistical incidences of a COPD patient that is also CHF ?

I don't know a number, but I bet it is high.

COPD leading to Pulmonary htn. Pulmonary htn leading to hypertrophic cardiomyopathy. BANG: COPD'er with CHF

No argument here ..

Q: Can auto peep be clinically measured ? For that matter what is auto peep ?Should auto PEEP be matched or exceeded

Hang on... gotta phone a friend on this one... where is his number?

See above explanation stop calling me at work !

Q: Name 3 complication with the application of CPAP.

Anxiety attack due to claustrophobia causing hyperventilation.

Agreed but can be overcome: This is something that a good practitioner can talk the patient through never use the explanation "this may be a bit claustrophobic sir/madam ... FAIL.

Recognising when the patient is in respiratory/ ventilatory failure and salvageable or or has already failed, needing a tube to survive. This is the most "difficult part" judgement and qualifying what patient will possibly tolerate and benefit. Then the biggest problem in quantifying success in any EBM study for EMS.

Decrease in BP

PERFECT: Ok now iatrogenic PEEP (think of the lungs being a dam between right and left side of heart, damn the flow and what happens ? yes hypotension, this with too much PEEP, or not enough exhalation time (bagging) = Dynamic Hyperinflation = PEA.

All the same problems as with IPPV (Barotrauma including pneumothorax, interstital/sub-q emphysema)

EZACTLY: aint that funny in Protocols just use in Pulmonary oedeama but don't use CPAP on Ashmatic or COPD ... RSI them ? huh ?

Thats all I got right now

Thats enough my Brain is going to explode and edit for opening quotes don't match end quotes AGAIN!

Edited January 6, 2011 by tniuqs

[D.P.Gumby]

Just a couple of pennies to add, hopefully the quotes all come out OK...

[...super discussion that I can only sit back and learn from, nothing productive to add...]

[tniuqs]

This may be a tad more concise than my mindless ramblings.

http://www.ccmtutorials.com/rs/PEEP/page7.htm

cheers

[DartmouthDave]

So when a patients Measured Minute Volume it must exceeded by a factor of 4 minimum, that is called a true High Flow System btw.<edit delete I:E ratios nonsense and say 1:4 is acceptable. So when one is breathing at 10 liters per minute, 10 lpm is extremis (normal MVs are average 3.5 to 5.5 lpm). Upon rapid inspiration and quite easily one can achieve 40 liters per minute, a patient can out breath or suck back for lack of fully functioning brain cell's at this juncture. ON ICU ventilators 120 lpm for flow rates are achievable ... that's to match the demands of a thoroughbred at a full gallop, if you catch my drift.

So in order to maintain PEEP The machine/ device whether it be a CPAP device BiPAP or a Ventilator or even a BVM with PEEP Gauge, once again inspiratory flow must exceed the MV x 4 so that the end pressure is not lost, to zero. If you do not a device that can exceed the positive pressure during inspiration then "demand exceeds supply" (for the economists out there) then one cannot assure loss of so ask yourself when looking at any device is this capable of even accurately measuring end exhalation pressures or is it just set somehow with flows and magic theory's ? Because if it is not and no way that you can measure, therefore "you may" or "may not' be maintaining PEEP.

Hello,

Night shift so bear with me. My question is weakly related to the discussion thus far.

OK. Flow needs to be x4 the MV in order to maintain PEEP.

So, with a transport vent (LTV or Oxylog 3000...for example)dose this mean the PSI drained from the oxygen tanks increse as PEEP is increased?

Cheers

[chbare]

Remember, if we are talking about an intubated patient receiving controlled ventilation (let's say volume), the flow is a function of how quickly the tidal volume is delivered. So, you can increase the flow, but the amount of gas delivered will be the same assuming the volume to be delivered remains constant. The said volume would be delivered faster resulting in a decreased inspiratory time however. CPAP in a spontaneously breathing patient may be a different story.

It can be confusing; however, CPAP & PEEP are physiological analogues, but can be delivered in different ways. Hopefully that makes sense.

Take care,

chbare.

[tniuqs]

chbare: The CPAP machines are all different in means of delivery of gas, I agree with your statement entirely but it may become clearer if I continue to elaborate.

Hello,

Night shift so bear with me. My question is weakly related to the discussion thus far.

OK. Flow needs to be x4 the MV in order to maintain PEEP.

So, with a transport vent (LTV or Oxylog 3000...for example)dose this mean the PSI drained from the oxygen tanks increse as PEEP is increased?

Cheers

Morning shift, after 8 hours drive / shovel 4 tons of snow off roof / but to late for collapsed boat garage I digress ... so bear with me zzzzzzzzzzzzzzzz LOL>

A good question and its been some time since I worked with Oxylog, the flight OZ guys had some issues with sticking exhalation block on the 1000 (a failure happened to me on a LTD fixed wing) and not so popular with me any more, I hope that the 3000 is got the bugs worked out.

The internal workings of the Oxylog and for some reason can not check 3000 (my Internet is in and out) .. but from memory the FiO2 controls are a combo, 1- a direct source gas limited to 50 psi FiO2 1.0 and or a .6 FiO2 (no blender) its 2- an internal venturi device and that increases flow capability (based on 50 psig tank) so on lower levels of FiO2 your actually achieving higher flow rates its highly unlikely on either setting one will have a loss of PEEP due to the patient exceeding demand.

The LTV even sweeter kit, (2 to 3 times the price of an Oxylog too) it is actually a turbine support system (no matter what the FiO2 is set) the LTV senses an increase in change and literally boosts the support/ flow (can't remember exact stage flow settings there is 3)

Here is the real point to this, but mobey never came back to answer the questions the EMS "CPAP" devices that are dependant on a wall mounted flow meter, (i.e compensated thorpe tube) is limited to 23 lpm hence if one is looking at the definition of a high flow system fail in the math alone and HIGHLY likely in real life as well ... 23 divided by 4 is 5.75 lpm and not a abnormally high normal MV for a spontaneous breathing adult.

That said on a ventilator, the patients entire WOB is removed (the whole idea sans maintaining open airway idea) therefore decreasing metabolic demands , resulting in a lower MV overall (and at that ventilated 5.75 lpm MV) matches CO2 production and your set FiO2 is matching or exceeding oxygen demands.

So in mobey speak: If you suck back hard to get a breath entirely possible one is pulling back so hardas to generate a negative intra thoracic inspratory pressure resulting in a loss of PPV / PEEP defeating the whole intent of the Constant Positive Airway Pressure idea, as it becomes an "intermittent" CPAP (only during exhalation does it provide "set" PEEP values). and in fact again one is using assesory muscle usage on "exhalation"

ps entirely possible is pulling the so hardthat one has NOT decreased the WOB, assisting the major muscle of ventilation (the diaphram)

Back to another point I tried to makefield level ... good clinical background and experience is the best indicator to evaluate the success OR imminent failure of any device like CPAP (although difficult to quantify in EBM studies)

cheers

cheers hope that helps.

[chbare]

However, some of these pre-hospital devices are able to significantly increase the flow by use of the Bernoulli principle and air entrainment. It's not the flow that concerns me so much, it's the pressure. Unfortunately, with air entrainment, it's a rob Pete to pay Paul situation. You have allot of flow, but the increased kinetic energy comes from somewhere. This somewhere happens to be in the form of decreased pressure or a decrease in potential energy. So, with inspiration, many of these devices provide flow, but I am not confident they can provide true continuous pressure during inspiration. So, you potentially get a device that provides 1/2 CPAP with inspiratory flow augmentation. Hey, that is a pretty cool, catchy phrase, I should market it as a new modality. Bet it would sell like crazy with such a fly name?

Take care,

chbare.

[tniuqs]

However, some of these pre-hospital devices are able to significantly increase the flow by use of the Bernoulli principle and air entrainment. It's not the flow that concerns me so much, it's the pressure. Unfortunately, with air entrainment, it's a rob Pete to pay Paul situation. You have allot of flow, but the increased kinetic energy comes from somewhere. This somewhere happens to be in the form of decreased pressure or a decrease in potential energy. So, with inspiration, many of these devices provide flow, but I am not confident they can provide true continuous pressure during inspiration. So, you potentially get a device that provides 1/2 CPAP with inspiratory flow augmentation. Hey, that is a pretty cool, catchy phrase, I should market it as a new modality. Bet it would sell like crazy with such a fly name?

Take care,

chbare.

Exactly: btw your physics background is showing .. the Bernoulli effect is pointless if one does not have forward flow. Yes the rob from peter to give to paul a perfect analogy applied.

further: NO possible WAY that a $50 dollar device can compare with a $2000 dollar device, yet that is what the EMS CPAP manufacture and marketing type devices are claiming. FAIL in applied logic level alone.

Agreed some EBM studies CPAP stays off the plastic tube and decrease mortality morbidity and lower's HC costs .. well sometimes, but implementing these plastic CPAP devices on a huge level in EMS, as if they are in any way comparable to a machine that is capable of delivering proper CPAP or BI Level support. (for that matter)

Back to this new soon to be patents pending INSPIRATORY FLOW AUGMENTATION MODE .. are you interested in investors chbare?

ps My Oxygen Bar and Patch making company are not doing well in this current economy

cheers