Questions on Mechanical Ventilators

zcoq72mehs · Dec 31, 2010

Increasing afterload [svr-systemic vascular resistance] by increasing mean arterial pressure (which we abbreviate MAP, btw, in our books) does not necessary improve cardiac index, oxygen delivery, but should indeed increase mvo2 (myocardial oxygen consumption rate), in addition to increasing ICP possibly in the neurological population........follow the dogs tail round and round.........one tried to avoid the deleterious effect in the first place, when possible. Our goal is not to maximize mean airway pressures in the ARDS patient, but instead to maximize oxygenation best we can considering their noncompliant tissue and alveolar membrane insult, etc.

But i get your drift.

I most definitely agree with you--ventilators are not about moving knobs. I highly respect RT's and pulmonogists and I defer to them readily. Generally speaking, RNs, lpns or what have you should not be managing a ventilator other than some immediately stabilizing effort (for those CFRN, CTRN and related populations) per MD orders or whatever means protects them as it is outside our scope of practice, generally speaking.

As for home nursing........LOL. How many of these nurses have you worked with? You think the majority of them can follow this conversation you have engaged?

I have much less confidence in that, having worked with them.............

But, again, home nurses are supposed to be calling the on-call RT and/or MD to make adjustments that go outside the prescribed range.

If some unstablizing condition presents itself, they are taught to call 911 and to use the ambu bag or what have you to maintain oxygenation/airway the best they can.......it is not their scope to think about what is the ideal ventilator change and make said implementation, IMO at least.

Many of those home nurses are not even acls or pals certified, let alone understand respiratory physiology and hemodyamics to a degree you have expounded upon in these messages--at least based on the couple dozen i have worked with at least.

Having said this.............

I am interested in improving my understanding of this topic.

Are there any textbooks you would recommend? I certainly have no interest in learning the materials to any degree that a new RT graduate would possess, as that is a degree in itself...........

Just some information to bring me up to speed to a level that you think a nurse should be, since you have brought up the subject (home nursing, in particular).

It would be much appreciated. I am basically now asking you for your help and can only hope you are willing.

Thank you in advance.

I understand you limitation which is evident by your use of MAP and PIP or PAP. I showed you how MAP is determined and why as well as all the factors influencing MAP. I also wrote about ARDS and lung protection protocols.
Managing a ventilator is very complex and it is more than just turning knobs. This is why protocols such as ARDS and Sepsis are written to cover both the RN and RT portions of patient care. If it is known the RT will have to increase the PEEP to increase MAP and oxygenation, the RN will have to make whatever adjustments to maintain adequate Mean Arterial Pressure. The SvO2 will also be of concern if running a sepsis protocol or SjvO2 for brain injuries with the appropriate adjustments to pressors and fluids. There may also be THAM or Bicarb running for permissive hypercapnia.
The only way the old is going to be replaced by the new is through education and change. Some hospitals are like stepping into 1970 with outdated equipment and methodologies. Some places do not readily implement EBM. Some MDs don't trust the staff or themselves enough to try something new. It is also disheartening to pick up or receive patients who have been poorly managed or even just mismanaged on a ventilator to where the damage will be permanent.
I am not being hostile but if the person posing those questions will be left alone in a subacute or home care situation without an RT and only knows the answers to the test and not the whys or hows, they could be caught in a very bad situation.
We wouldn't want this to happen to anyone.
https://allnurses.com/nursing-news/man-catches-home-512711.html

zcoq72mehs · Dec 31, 2010

re:

man-catches-home-512711.html

That is a tragedy.

I feel for all involved. Wrong on many levels.

GreyGull · Dec 31, 2010

As for home nursing........LOL. How many of these nurses have you worked with? You think the majority of them can follow this conversation you have engaged?
I have much less confidence in that, having worked with them.............
But, again, home nurses are supposed to be calling the on-call RT and/or MD to make adjustments that go outside the prescribed range.
If some unstablizing condition presents itself, they are taught to call 911 and to use the ambu bag or what have you to maintain oxygenation/airway the best they can.......it is not their scope to think about what is the ideal ventilator change and make said implementation, IMO at least.
Many of those home nurses are not even acls or pals certified, let alone understand respiratory physiology and hemodyamics to a degree you have expounded upon in these messages--at least based on the couple dozen i have worked with at least.

The LTC and home care RNs must have an understanding of the basic terms like MAP and PIP. They also must be able to explain the 3 questions which started this conversation. I wouldn't want someone's life hanging on the edge while an RT or MD is paged. EMS is also not going to come for every alarm and may have a much longer than a 4 minute response time. There are also many different types of EMS providers which may have little to no training with trach patients. The point is that you need to recognize a situation before it becomes an emergency. You do not need ACLS or PALS for that. Just knowing how to call 911 is not the answer if someone's continued care and life is in your hands.

I participate in the education of patients, families and their home care providers (RNs, LVNs, CNAs etc) so I do have something vested in knowing they are secure with their knowledge when they leave our facility. This goes for patients who are infants up through adults. Somehow we have been able to send patient home successfully for over 30 years and many of the direct care providers are RNs and LVNs along with family members who do not even have a high school diploma. Somehow they still manage to grasp some very important principles about their loved one or patient's disease process and ventilator. It is definitely within everyone's "scope" to think about how, what and why when they are working with a ventilator patient. Home care nurses should not be mindless order takers and also can have a great input in facilitating a weaning plan at home.

zcoq72mehs · Jan 1, 2011

you didnt make any recommendations.

i think you keep implying that i do not know what mean airway pressure is, nor peak inspiratory pressure. I do know what they mean.

I also understand many of their implications.

If I do not, feel free to educate and define them to your liking so that there is no question as to what i do or do not know, and thereby help the beforementioned ppl you claim to educate as I am one of the populus.

It is doubtful that high frequency ventilation (hvoc) would have even been created had it not been for the associated complications of high mean and peak airway pressures (barotrauma etc), ntm the beforementioned reduced cardiac index/output frequently due to decreased venous return (starlings law, etc), which then may lead to the arterial pressure drop you mentioned needed to be rectified by the RN.......but let us follow our tails by inducing lung trauma unnecessarily (since you seem to indicate it is the goal to increase airway pressures), reducing CO/CI, and then follow our tail around by utilizing volume (which invariably interstitial-izes) and/or pressors, thereby increasing afterload, mvo2 consumption, ICP, etc etc etc.

You need to walk past that and/or provide your education as to lift the cloud of ignorance and 'save' more patients and its associated affected.

Now, the recommended resources, please, and the education you provide to the mentioned population, please.

Thank you in advance.

Not trying to insult, but trying to get meaningful information from you is laborious.

You seem to be knowledgeable on the subject matter, our [are] quick to challenge statements, yet provide no response to direct questions that would only lead to improved quality of care, all around.

Please do tell and let go of the unnecessary criticism.

The LTC and home care RNs must have an understanding of the basic terms like MAP and PIP. They also must be able to explain the 3 questions which started this conversation. I wouldn't want someone's life hanging on the edge while an RT or MD is paged. EMS is also not going to come for every alarm and may have a much longer than a 4 minute response time. There are also many different types of EMS providers which may have little to no training with trach patients. The point is that you need to recognize a situation before it becomes an emergency. You do not need ACLS or PALS for that. Just knowing how to call 911 is not the answer if someone's continued care and life is in your hands.
I participate in the education of patients, families and their home care providers (RNs, LVNs, CNAs etc) so I do have something vested in knowing they are secure with their knowledge when they leave our facility. This goes for patients who are infants up through adults. Somehow we have been able to send patient home successfully for over 30 years and many of the direct care providers are RNs and LVNs along with family members who do not even have a high school diploma. Somehow they still manage to grasp some very important principles about their loved one or patient's disease process and ventilator. It is definitely within everyone's "scope" to think about how, what and why when they are working with a ventilator patient. Home care nurses should not be mindless order takers and also can have a great input in facilitating a weaning plan at home.

GreyGull · Jan 1, 2011

You seem to be knowledgeable on the subject matter, our quick to challenge statements, yet provide no response to direct questions that would only lead to improved quality of care, all around.
Please do tell and let go of the unnecessary criticism.

I'm only challenging you because of the information you are providing. I've already mentioned HFOV which we start MAP at 2 cmH2O higher than conventional for neonates and 5 cmH2O higher for adults. You have to understand these types of ventilators and see the relationship between MAP of both arterial and airway and oxygenation. I've also mentioned lung sparing ventilation. I can not keep repeating myself.

but let us follow our tails by inducing lung trauma unnecessarily (since you seem to indicate it is the goal to increase airway pressures),

You don't see the relationships or want to understand any of the factors that go into airway pressures and running a lung protective protocol. I have given you all the buzz words and info that you can look up in almost any nursing critical care textbook that has a ventilator and ARDS section.

You need to walk past that and/or provide your education as to lift the cloud of ignorance and 'save' more patients and its associated affected.

I have no clue what you are talking about here. You want me to make a general statement to cover all patients when I want to impart the basic principles and concepts that allow you to get started towards understanding oxygenation, ventilation and ventilator safety.

I could recommend alot of books but I doubt if you would agree with any of them since they will mention the same factors that go into Mean Airway Pressure that I have. BTW, a high MAP does not necessarily mean a high PIP.

zcoq72mehs · Jan 1, 2011

i know........map will be raised with peep, as inspiratory pressures are only part of the equation.

well, thank you for the information you did share.

i am not asking you to repeat urself with hfov--just saying that it probly wouldnt have been created had high airway pressures been the desired goal u want so badly to implement.

i have several critical care texts, one of which is civetta......a whole book shelf of nursing, medical, and respiratory textbooks about 4feet by 6 feet, many read, all consulted at one time or another.

you failed to answer the questions, as usual.

Actions speak louder than words. If you truly did want to help, you would have been able to hear the plead, rather than be dismissive by your action here, or lack thereof, actually.

I understand many concepts in regard to oxygenation, ventilation, and ventilator safety. Because we differ in opinions, you may feel that i do not--despite my repeated request for further, specific, information.

In any case, I am not standing aside and stand firmly on the opinions i made, and will not faulter based on the posts of an unknown, unproven entity who seems to be dead set on maintaining high airway pressures as the 'goal' of some protocol.

Sounds awfully cookbook and shortsighted to me.

Protocols exist as guidelines, and just because the ARDS protocol may indicate that higher airway pressures may be necessary, does not imply that they are a goal in itself, as what is a goal is the whole clinical picture--use the minimal necessary airway pressures to obtain the given goal of maximizing oxygen delivery, with the understanding that it may be necessary and helpful to implement higher than normal pressures for that given situation/clinical presentation.

The 20+ something protocols, and steps in those protocols, are not necessarily meant to imply that the steps that have been proven to be effective are the GOAL/OBJECTIVE (because oxygen delivery is, my friend) and the effects of those steps should be done in isolation without understanding and balancing possible side effects, if you will.

With lowered compliance and membrane dysfunction it is understood that protocols indicate higher-than-normal airway pressures as a way to conter-act said condition--this does not mean it is the goal or objective in itself--but this intervention was necessary to maximize oxygen delivery, all other factors considered.

The same logic can be used for fio2. Just because a higher fi02 may increase the carrying capacity of a given ml of rbc, doesnt mean we should not use the lowest fio2 necessary........using the highest fio2 to achieve the necessary clinical result is not the goal. Instead, we want to minimize any potential deliterious effects of oxygen, and use only the amount optimal for the given patient--it is not a goal or objective to increase fi02, just like it is not a goal to increase airway pressures. Our goal/objective is not to use the highest airway pressures, but instead to try to minimize the effects of those airway pressures, but realizing that the protocol, which was based on plenty of research, indicates that we will need to use higher-than-normal pressures to meet that optimal outcome/goal.

It is not my fault that you can not understand this.

It is never a GOAL/OBJECTIVE to maintain high airway pressures, period.

It is the goal to make optimal oxygen delivery.

There are many protocols for disease processes that are based on research that indicate that XYZ has proven to be optimal the majority of the time...........the steps in each of those protocols themselves are NOT the goal. Just because it calls for a PEEP of 12 or whatever does not mean it is some desired objective and that it should not be questioned and it should be looked at in isolation, independent of what it may do to the calculated oxygen delivery in a given patient.

Let the patient and the patient clinical presentation dictate the situation......who cares if the protocol asks for 12cm of peep if oxygen delivery decreases, if myocardial oxygen consumption increases, if intravascular volume is third spacing, if more drugs/sympathetic stimulators are being used with their own untoward vasonstrictor effects (read renal perfusion, cerebral perfusion, coronary perfusion).

Sure, your ventilator paramaters may look great on paper.

But who cares if the patient's actual clinical presentation, which is measurable, does not adhere to your protocol, your cookbook medicine.

Statistics are just that..........a nice bell curve.

Indeed, we need to be able to THINK, and not blindly assume because your protocol asks for a higher peak airway pressure, that it is the next best sliced bread, and that we should ignore anything else because the statistics are in our favour.

I stand behind what i said, alright: maintaining high airway pressures is NOT a goal, but instead, oxygen delivery is--and in some cases, in some disease processes, the protocols have shown us that we have to use a potentially deliterious measure to achieve that goal--we must increase the airway pressures........and that this usually improves outcomes.

You seem to think that because we have to do something that is less than ideal, that it means THAT is our goal, that we WANT high airway pressures--that it is the high airway pressures that we desire so much--no, it is the lesser of the two evils. We are increasing the patient risk of possible deliterious effects of high airway pressures to obtain the goal of optimal oxygen delivery in a situation wherein there is noncompliant lungs and membrane dysfunction.

misconstrue your protocols as you will............that is your business.

It is important to consider the protocol, and to understand its implications, anticipate them, and keep it balanced on BOTH sides.......add some peep, without the desire to use the maximum airway pressure possible to achieve the goal, of uh, what? high airway pressures? No, we are going to measure some stuff, arent we--and it has to do with oxygen delivery, doesnt it?? Yes, i thought so. Our goal is oxygen delivery, sir, not your high airway pressures. And we may need to back off on that pressure, huh? Uh, no? It may break the rules of your protocol?

Thanks for the dialog.

I'm only challenging you because of the information you are providing. I've already mentioned HFOV which we start MAP at 2 cmH2O higher than conventional for neonates and 5 cmH2O higher for adults. You have to understand these types of ventilators and see the relationship between MAP of both arterial and airway and oxygenation. I've also mentioned lung sparing ventilation. I can not keep repeating myself.
You don't see the relationships or want to understand any of the factors that go into airway pressures and running a lung protective protocol. I have given you all the buzz words and info that you can look up in almost any nursing critical care textbook that has a ventilator and ARDS section.
I have no clue what you are talking about here. You want me to make a general statement to cover all patients when I want to impart the basic principles and concepts that allow you to get started towards understanding oxygenation, ventilation and ventilator safety.
I could recommend alot of books but I doubt if you would agree with any of them since they will mention the same factors that go into Mean Airway Pressure that I have. BTW, a high MAP does not necessarily mean a high PIP.

GreyGull · Jan 1, 2011

All I have to say is go back and review oxygenation, the various airway pressures and the lung protective concepts which also utilizes PEEP. There is no way to discuss anything further until you realize the roles each factor of MAP (airway) has on oxygenation and protecting the lungs from higher FiO2, volutrauma and barotrauma.

Our protocols and ventilator management guidelines are based on EBM and a thorough understanding of ventilators and disease processes. They are not cookbook recipes and some are over 12 pages in length for both RTs and nurses. They cover many different pathways for the ventilator, hemodynamics and the medications. We don't just sit around waiting for the sun to rise and a doctor to come in to tell us what to do.

add some peep, without the desire to use the maximum airway pressure possible to achieve the goal, of uh, what? high airway pressures?

Maximum airway pressure? Is this Mean Airway Pressure? PEEP is one factor to manipulate to obtain better oxygenation through MAP and decreasing volutrauma with a small VT which is a lung protective strategy.

You are the one who is running together all the pressures without making any significance of them except they are all bad. It also looks like you are pulling stuff off the internet at random and out of context.

GilaRRT · Jan 1, 2011

Well, this doesn't seem to be going anywhere...

GreyGull · Jan 1, 2011

Well, this doesn't seem to be going anywhere...

Is that all you have to offer? Aren't you a Respiratory Therapist and an RN?

zcoq72mehs · Jan 1, 2011

GilaRN,

Well, it did.

:)

I have purchased two books after this conversation.

Little did i realize a barely-related google search was going to get me thinking about this subject the way it has.

I will be reviewing and building my knowledgebase, even tho in my situation i would not be making these critical decisions--i indeed refer to the RT, pulmonary team, etc.

It has been too long since i have read a book covering many of these ventilator modes and 'published' protocols/guidelines set out by those committees.

That time has arrived.

I did enjoy the dialog and conversation, altho i do believe it could have been more constructive from the beginning.

I waited a long time for grey whomever to answer the questions and provide detailed rationales as to why the answers were what they were--to provide an associated clinical scenario if you will. Unfortunately, I failed in elicting that response.

I also feel he/she could have provided lucid information that may have been beneficial to many ppl, and that knowledge could have trickled down, affecting many other lives.

I value his/her time: thank you.

Well, this doesn't seem to be going anywhere...

zcoq72mehs · Jan 1, 2011

no, i didnt pull anything off the net for these messages. Because I understood the concepts in the first place while i learnt them, the need for memorization was minimized, and much information was retained, probably beyond the norm 10% average.

i do understand that peep allows maximum oxygenation, one way via maintaining alveolar and its associated 'tubes' from collapsation, if you will, and by maximizing this time for the diffusion of gases, that we can use lower fio2 and volumes (we need less volume to achieve the same result because the gas we did deliver is being used more efficiently via open alveoli, etc)

greygull, i do appreciate what you have shared.........

:)

thanks.

I do recognize your knowledegable information, and your effort. It is not in vain, GreyGull, even tho you may have found it frustrating, as i did also.

All I have to say is go back and review oxygenation, the various airway pressures and the lung protective concepts which also utilizes PEEP. There is no way to discuss anything further until you realize the roles each factor of MAP (airway) has on oxygenation and protecting the lungs from higher FiO2, volutrauma and barotrauma.
Our protocols and ventilator management guidelines are based on EBM and a thorough understanding of ventilators and disease processes. They are not cookbook recipes and some are over 12 pages in length for both RTs and nurses. They cover many different pathways for the ventilator, hemodynamics and the medications. We don't just sit around waiting for the sun to rise and a doctor to come in to tell us what to do.
Maximum airway pressure? Is this Mean Airway Pressure? PEEP is one factor to manipulate to obtain better oxygenation through MAP and decreasing volutrauma with a small VT which is a lung protective strategy.
You are the one who is running together all the pressures without making any significance of them except they are all bad. It also looks like you are pulling stuff off the internet at random and out of context.

NeoPediRN · Jan 12, 2011

Breaths are delivered by the ventilator either by a controlled breath or a pressure supported breath but who or what initiated the breath is different. It would be rare today to not use a pressure supported breath with SIMV. In the Eagan book you read from over 20 years ago it may still have discussed the patient breathing spontaneously from a free flowing bag attached inline to the ventilator.

Our hospital no longer refers to it as SIMV. It is pressure support with a rate here.