# CPAP Indications



## valbq2 (Dec 18, 2008)

For those of you that have a CPAP protocol, what does it state for use with asthma patients?  Our protocol states asthma is not a contraindication, but it is a precaution.  I am having a hard time understanding the pathophysiology behind this.  It seems like CPAP would be very helpful in asthma when combined with bronchodilators, because it would splint the airways open, push mucous out of the way, and push the bronchodilators into the alveoli.  I understand that asthma patients are having trouble with exhalation due to constricted bronchioles and mucous production.  The RT who introduced this protocol stated CPAP would not allow the pt to exhale, but if you are getting the airways open, it should resolve that problem.  I'm sure Bi-PAP is a better option, because you can set a lower pressure for exhalation.  I have used CPAP on asthma pts before, and it prevented the necessity of intubation.  The patients improved drastically.  So, I don't understand the problem.  Can anyone explain more?


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## Onceamedic (Dec 18, 2008)

CPAP does NOT move mucus or pus (thus not useful with pneumonia).  It only drives water out of the space between the alveolar and the capillary surface by driving it back into the circulation.  You gotta remember that these are microscopic structures - "splinting" just doesn't happen.  I know Ventmedic would be able to shed a lot more light on it - respiratory structures are a lot more complicated than what you depict.  Furthermore, bronchodilators are of no use whatsoever in the alveoli.


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## VentMedic (Dec 18, 2008)

You don't want to PUSH mucus down further. If mucus is a problem, dry air may turn it to cement and make it more difficult to expel. Plus, it is very difficult to cough with CPAP. 

CPAP can enhance air-trapping and the patient may feel as if they can not exhale. 

BiPAP (trade name for Respironics) means two levels. You can adjust CPAP just as you can the lower level of BiPAP.

CPAP can splint the airways open but it will also depend on your device. External resistive valves in a system with very low or very high flow capabilities can increase work of breathing. CPAP machines with internal PEEP and variable flow capabilities adjust to better accommodate the patient. 

CPAP should not PUSH bronchodilators into the airways. The turbulent flow will inhibit adequate deposition of medication particles. Much of the nebulized meds will also exit through the mask ports.  The extra flow from the nebulizer may also increase work of breathing through the exhalation valve. 

BTW: Where do you want the medication particles to target? 

There is nothing wrong with CPAP on some asthma patients but if the words PUSH or FORCE are used in the description its use, one may not fully understand the proper use of it.


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## AlaskaEMT (Dec 19, 2008)

Thanks Vent.


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## MSDeltaFlt (Dec 19, 2008)

valbq2 said:


> For those of you that have a CPAP protocol, what does it state for use with asthma patients?  *Our protocol states asthma is not a contraindication, but it is a precaution. * I am having a hard time understanding the pathophysiology behind this.  It seems like CPAP would be very helpful in asthma when combined with bronchodilators, because it would splint the airways open, push mucous out of the way, and push the bronchodilators into the alveoli.  I understand that asthma patients are having trouble with exhalation due to constricted bronchioles and mucous production.  The RT who introduced this protocol stated CPAP would not allow the pt to exhale, but if you are getting the airways open, it should resolve that problem.  I'm sure Bi-PAP is a better option, because you can set a lower pressure for exhalation. * I have used CPAP on asthma pts before, and it prevented the necessity of intubation*.  The patients improved drastically.  So, I don't understand the problem.  Can anyone explain more?





VentMedic said:


> You don't want to PUSH mucus down further. If mucus is a problem, dry air may turn it to cement and make it more difficult to expel. Plus, it is very difficult to cough with CPAP.
> 
> CPAP can enhance air-trapping and the patient may feel as if they can not exhale.
> 
> ...



PEEP is CPAP with a rate.  When you have an asthma attack, you're auto-PEEPing.  When a CPAP mask is added to someone who's auto-PEEPing, it has the potential of exacerbating the issue.  And, as Vent mentioned, can be counterproductive depending on the flow and how weak the pt is.  That's why it is a precaution and not a contraindication.


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## VentMedic (Dec 19, 2008)

VentMedic said:


> CPAP should not PUSH bronchodilators into the airways. The turbulent flow will inhibit adequate deposition of medication particles. Much of the nebulized meds will also exit through the mask ports. The extra flow from the nebulizer may also increase work of breathing through the exhalation valve.


 
I am going to clarify this a little.  There are devices that do allow for a nebulizer to be placed inline and others are rigged.   To this date there have been few studies on the depositon of the nebulized particles with prehospital machines. Just misting the face and getting the medication to where it needs to be are two different things.   Even the acorn nebulizer only delivers a small percentage of the medication with a face mask.   That is why hospitals have other types of nebulizers to ensure more medicine is delivered.    

Interesting article:

http://www.aarc.org/marketplace/reference_articles/11.99.1353.pdf

Yes, RRTs do take nebulized particles very seriously.


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## Melbourne MICA (Dec 27, 2008)

MSDeltaFlt said:


> PEEP is CPAP with a rate.  When you have an asthma attack, you're auto-PEEPing.  When a CPAP mask is added to someone who's auto-PEEPing, it has the potential of exacerbating the issue.  And, as Vent mentioned, can be counterproductive depending on the flow and how weak the pt is.  That's why it is a precaution and not a contraindication.



I would like to say soemthing about this. PEEP - positive end expiratory pressure is not the same as CPAP - continuous positive airway pressure. Thus PEEP is not "CPAP with a rate". Asthma is a kind of "autopeeping"? Sort of though in asthma the resistance is at the small airway level whilst PEEP is done at the top of the airway tree applied only at the end of the expiratory phase - it can be done manually or via a ventilator the difference being the ventilator will apply a specific and consistent pressure whereas the manual method is guesswork by the operator. This is why PEEP is not useful in the asthma pt - you are adding resistance at the end of the exhalation on top of the resistance already being fought to overcome down in the small airways. 

CPAP applies airway pressure through the complete ventilation cycle and can only be done effectively through a ventilator. 

CPAP or BIPAP in the asthma pt (not used universally -still controversial) is generally left for the pt who has reached the stage of severe and life threatening expiratory and inspiratory obstruction  - they will get hypoxic fast from this point with only one outcome if gas exchange cannot be restored - death. This explains why we typically see asthma pts treated with just steroids and bronchodilators not ventilators.


BIPAP, PEEP CPAP etc are coming into much wider use for a variety of respiratory pathologies including their use in the triumvirate of COPD - asthma/emphysema/bronchitis - and are producing impressive results regrettably only in the short term for some like the emphysema pt. 

All these pathologies will produce variously, copious mucous, bronchoconstriction through smooth muscle spasm, alveolar collapse to one degree or another (atelectasis) and significant inflammation of the lumen of the various sized airways (bronchiectasis - this leads to bronchiolar remodelling in the long term) - the end result is ultimately very similar - airway narrowing, changes in intrathoracic pressures affecting ventilation efficiency, hyperinflation, hypercapnoea and reduced gas exchange at the alveoli. Even more complex is how all this interacts with perfusion in the lungs.

The whole subject is a highly complex one - have a chat to a respiratory specialist next chance you get and you will see what I mean.

The value of BIPAP particularly for the pt with LVF is that the positive pressure component of the ventilation cycle assists with maintaining alveolar expansion and fluid shift via the lymphatic system whilst reducing the workload on the pt with exhalation - remember the pt is trying to inhale air through the physical barrier of the inspisatious secretions accumulated in the alveolar and small bronchiolar airways -tough work for the fittest person let alone when your eighty years old. Physical exhaustion from the sustained effort often precedes the point of respiratory collapse - we have all seen the tired respiratory pt - a warning sign indeed for immediate aggressive interventions.

For many respiratory pts the real value of such ventilation systems has been in removing the need to intubate thus reducing complications, reducing hospital stays and costs and lCU bed and other issues.

It's been a fantastic innovation helping many pts and a great addition to the arsenal of ambulance skills.

Long as always - hope the points were of interest.

MM


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## VentMedic (Dec 27, 2008)

Melbourne MICA said:


> I would like to say soemthing about this. PEEP - positive end expiratory pressure is not the same as CPAP - continuous positive airway pressure. Thus PEEP is not "CPAP with a rate". Asthma is a kind of "autopeeping"? Sort of though in asthma the resistance is at the small airway level whilst PEEP is done at the top of the airway tree applied only at the end of the expiratory phase - it can be done manually or via a ventilator the difference being the ventilator will apply a specific and consistent pressure whereas the manual method is guesswork by the operator. This is why PEEP is not useful in the asthma pt - you are adding resistance at the end of the exhalation on top of the resistance already being fought to overcome down in the small airways.
> 
> *CPAP applies airway pressure through the complete ventilation cycle and can only be done effectively through a ventilator. *


 
To say *PEEP is CPAP with a rate,* as MsDeltaFlight did*,* is correct in that the term PEEP is associated with modes that provide a rate or assisted breaths for ventilation. CPAP is generally thought of as a mode by itself.

A lot of this depends on the machine design for delivery and the manufacturer's use of the terms PEEP and CPAP. 

If it is a single limb ventilator, as many transport vents are, a resistive or PEEP valve may be used on exhalation to create the PEEP or CPAP from the forward flow on exhalation.

Even the Pulmonetics LTV transport ventilator used an external PEEP valve (resistive) until their 1200 series. This is common with many single limb transport ventilators. So essentially they are using a similar concept as the resistive valve and mask which is what prehospital is using. 

However; 

_Although it is the most ubiquitous form of ventilatory support, positive end expiratory pressure (PEEP) remains a large area of confusion for most physicians. For a start, the term PEEP is an anachronism, as the positive pressure is actually applied throughout the respiratory cycle and is more correctly termed “continuous positive airway pressure (CPAP)”; _
http://www.ccmtutorials.com/rs/PEEP/page1.htm

Good statement but it pertains to ICU or double limb circuit ventilators. 


*Auto-PEEP is gas trapped in alveoli at end expiration, due to inadequate time for expiration, bronchoconstriction or mucus plugging. It increased the work of breathing.* 


Auto-PEEP is caused by gas trapped in alveoli at *end expiration*. This gas is not in *equilibrium with the atmosphere and it exerts a positive pressure,* increasing the work of breathing,

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



> Sort of though in asthma the resistance is at the small airway level whilst PEEP is done at the top of the airway tree applied only at the end of the expiratory phase -


 
Mechanical ventilators or other external devices deliver from the top. Patients can do their own form of PEEP against the glottis by pursed lip breathing or babies use grunting. Grunting results from the partial closure of the glottis during forced expiration in an effort to maintain FRC.

However, if it is the result of over ventilation mechanically, it is inadvertent Auto-PEEP and measurements are done religiously on some patients to monitor this. 

Good case study on this concept:
*[FONT=arial, helvetica]Cardiovascular Instability Caused by Inadvertent Positive End-Expiratory Pressure in a Patient with Panlobular Emphysema Receiving Mechanical Ventilation [/FONT]*

http://www.ajronline.org/cgi/content/full/174/5/1339

Good brief overview and intro to mechanical ventilation:
http://www.ccmtutorials.com/rs/index.htm




> CPAP or BIPAP in the asthma pt (not used universally -still controversial) is *generally left for the pt who has reached the stage of severe and life threatening expiratory and inspiratory obstruction* - they will get hypoxic fast from this point with only one outcome if gas exchange cannot be restored - death. This explains why we typically see asthma pts treated with just steroids and bronchodilators not ventilators.


 
Once they reach that point, they get an ETT. CPAP or even BiPAP is effective if it can be done early enough. Many of the prehospital and a few old ED machines can only reach an FiO2 of 0.30. Also, by design on these machines, the higher the FiO2, the less flow available to the patient due to the mechanisms of entrainment. 

Asthmatics may also need HeliOx to assist in ventilation which can be done through a mask such as a NRBM or a few ventilators. At this time, CPAP/PEEP is provided through a ventilator designed to handle HeliOx. 

BiPAP is also not the correct term unless you are using a Respironics machine. You can also get into many variations of two level delivery. 

Some machines also use the terms EPAP instead of PEEP but may or may not use CPAP to designate the MODE of CPAP. 

Good article about CPAP and PSV/PEEP.
*Physiologic Effects of Noninvasive Ventilation during Acute Lung Injury *
http://ajrccm.atsjournals.org/cgi/content/full/172/9/1112/


*Effects of the Components of Positive Airway Pressure on Work of Breathing During Bronchospasm*
http://www.medscape.com/viewarticle/470756_1

This is a good read for those working with "PEEP" valves (resistive devices) to deliver either PEEP or CPAP. 

*Barotrauma from CPAP Systems Lacking Pressure Relief*
http://www.mdsr.ecri.org/summary/detail.aspx?doc_id=8145


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## VentMedic (Dec 27, 2008)

The reason I posted several links is to demonstrate how many variations there in terms with just NIV (non invasive ventilation).

I also want some to think about SCIENCE and EMS. Reading JEMS is okay but reading the journals they site at the end of the articles is better. Everyday in a hospital, healthcare professionals must be prepared with the latest and greatest research if they engage in conversations with the physicians and wish to make a point to change the plan of care. You can't say "because we always done it that way". 

When we get a new doctor, the RRTs usually check to see if he/she is from "Bear" or "Bird" country. Then we would know what ventilation concepts they are most familiar with and can use that in orientating the physician to the unit and their protocols. Bear and Bird were once two leading manufacturers of ventilators. 

The field of pulmonary medicine is very large with a tremendous amount of information to just cover the basics. Many Paramedics only get a very, very brief introduction to this world. Unfortunately, even the principles of mechanical ventilation are dummied down way too much which gives some the impression of "is that all there is to it?". Thus, they don't go on to actually understand the concepts. It just becomes a few terms and the practice of knobology. 

Many schools fail to even teach the basics of oxygen delivery, oxygenation, ventilation and V/Q mismatching. Thus, when it comes to using a pulse oximeter or ETCO2 monitor, many only know what they have been told by someone who may also not have much or any education with these concepts. If you do not have adequate foundation for knowledge, you will not always be able to figure out what is BS or more gently put; not enough education to know even the basic priniciples but just enough to be dangerous. That is why, at the very least, two semesters of college A&P should be the prerequisite. 

I could go into pages about just the simple O2 devices such as NCs and masks. Few understand why just reciting a recipe for 2 L/M by NC or 4 L/M is ridiculous since the FiO2 will be determined by the patient rather than the device.  Oxygen delivery is unfortunately taught by memorization and not by the mechanism or concept.

I would advise any EMT(P) class or co-workers to start a monthly journal club. They can easily be discussed online if properly initiated. Even email can be an acceptable means of discussion.


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## medic5740 (Dec 27, 2008)

*Education?*

Wow!  It sounds like I never got any education related to this topic, and yet CPAP equipment is on our ambulance.  
Ventmedic, do you know of any good educational program related to this topic?  Just how much information do you think that a paramedic with this equipment should know considering (s)he may only use it a couple of times per year?  
I am definitely interested in knowing about this topic.  Can you help me gather the information that I obviously do not have?


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## VentMedic (Dec 27, 2008)

First thing to do is to read the manual for your CPAP device thoroughly. See what studies it sites for research in testing this device. If none listed, contact the company or rep. 

This link gives you a good overview:
http://www.ccmtutorials.com/

Good material, free unless you want CEUs.
http://www.smithseminars.com/online-courses.php

More good free stuff;
http://www.uthscsa.edu/respiratorycare/onlinece.html

New ventilator modes
http://www.uthscsa.edu/respiratorycare/vent_modes.htm

*EXCELLENT* site for ETCO2 and CPAP/BiPAP.
Respironics is a leading manufacturer in this industry.
Registration is free and easy.
http://elearning.respironics.com/index_f.asp


Journals:

American Journal for Respiratory and Critical Care Medicine
(archived issues > 6 months available in Full, abstracts available on all)

http://ajrccm.atsjournals.org/

RC Journal
Articles available in full after 1 year.
http://www.rcjournal.com/

I am hoping these links will work for you. They are from the Jan 2009 issue with is devoted to NIV.

Good editorial on NIV
http://www.rcjournal.com/contents/01.09/01.09.0038.pdf

The Physiologic Effects of Noninvasive Ventilation 
http://www.rcjournal.com/contents/01.09/01.09.0102.pdf​ 

Noninvasive Ventilation for Patients Presenting With
Acute Respiratory Failure: The Randomized Controlled Trials
http://www.rcjournal.com/contents/01.09/01.09.0116.pdf​ 
Which Ventilators and Modes Can Be Used
to Deliver Noninvasive Ventilation?  (This one is for the Australian gentleman.)
http://www.rcjournal.com/contents/01.09/01.09.0085.pdf​


As you can see, RRTs love their evidenced based medicine and are very active in research. They rarely take anything as "just because" or just from hearing "it worked for so and so". Also, when reading any research, look at the type of equipment and methods used to validate the study. CPAP on one device may not produce the same data on another device. The journal articles I linked also pertain primarily to hospital machines which have a similar mode of CPAP concept but the delivery has a greater chance to be very effective. When reading any articles in JEMS, look at the references sites and find the original journal article. Different studies have different results. Someone will write an article and others will attempt to duplicate the study to prove or disprove. No one research article is ever taken as "the word and only word" of the respiratory Gods. ​ 
How much you should know as a Paramedic? That all depends on you. You may not need to know about all of the equipment but you may need to know more about pathophysiology. It also depends on if you want to do CCT or IFT from ICUs.​


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## Airwaygoddess (Dec 27, 2008)

*Wonderful links*

VentMedic, thank you for all of the great links!  ( boy do I have some reading to do!) ^_^^_^


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## Melbourne MICA (Dec 28, 2008)

VentMedic said:


> To say *PEEP is CPAP with a rate,* as MsDeltaFlight did*,* is correct in that the term PEEP is associated with modes that provide a rate or assisted breaths for ventilation. CPAP is generally thought of as a mode by itself.
> 
> A lot of this depends on the machine design for delivery and the manufacturer's use of the terms PEEP and CPAP.
> 
> ...



Thats a great post Venty and I stand corrected on a number of points.As far as the asthmatic goes I am not really sure why I didn't state that ETT is the end point for the severe asthmatic - It should have been obvious to me as this is precisely what we will do in the field for the catatonic, unconscious, or resp arrested asthmatic.

One thing I think I did get right was to say what a fantastically complicated subject this is. I also agree and recognise the confusion with terminology particularly PEEP/CPAP. 

It would seem much of it depends on whether you are coming at it from a commercial ventilator companies view point about the functions of their equipment or are just describing mechanical ventilation from a clinical/pathophysiologic point of view or even reflecting schools of thought from individual docs or hospitals/ICU's/ED's.

In Melbourne at least it is not my experience to see ventilators widely used on asthmatic patients - there is some variation from hospital to hospital - schools of thought or proponents there of - but for the most part they receive pharmacological interventions by neb mask and IV followed by intubation. I can't offer any insights as to what goes on in ICU for the sickest patients as regards current equipment (perhaps its about time I had another visit up there).

Once again, a fantastic post with much to dwell upon for all of us especially me.

MM


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## VentMedic (Dec 28, 2008)

Melbourne MICA said:


> In Melbourne at least it is not my experience to see ventilators widely used on asthmatic patients - there is some variation from hospital to hospital - schools of thought or proponents there of - but for the most part they receive pharmacological interventions by neb mask and IV followed by intubation. I can't offer any insights as to what goes on in ICU for the sickest patients as regards current equipment (perhaps its about time I had another visit up there).


 
My reference for ventilators on asthmatics was intended more for the hospital setting. The few EMS companies in the U.S. that do carry portable ventilators use ones that are more the ATV model and I would NOT trust any acute asthmatic to be placed on one unless the provider was an RRT with some experience. Although hand bagging has its own risks also.

Some Paramedics with flight and CCT do have access to more sophisticated technology but the brief overview some get in a "CCEMT-P or CCT" course barely covers the "knobology" part. I would just be happy if some would put a bacteria filter at the inspiratory flow outlet to protect the patients they pick up or bring to our hospital. Even using an HME/filter at the airway to protect the providers is too much to a ask of some. 

As for as the PEEP issue, some purists just use the definition as it is stated: Positive End Expiratory Pressure - a net gain in pressure in the airways at end exhalation. The valving and ability of the ICU ventilators to process information are constantly changing. But, with a cost of $40,000 - $100,000 a piece, it is like buying a car and you expect it to be loaded with options. 

I could get into the many new modes that are available on the ICU ventilators which Rich Kallet RRT does touch on in the article, *The Physiologic Effects of Noninvasive Ventilation.*

CPAP/PEEP and two level ventilation are not new. If some would only read the medical journals they would know how the disease processes are being treated in the hospital and may start to question some of their own protocols or at least wonder if anything new might come to prehospital. CPAP has been around for well over 50 years and I have done it on transport over 25 years ago. I could use Lasix and a whole host of other treatments that have changed. Some in EMS complain that they are having "things taken away from them" but if they had kept up with the literature they would have noticed the rest of the medical world no longer used some treatments and had moved on as medicine progresses.


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## Melbourne MICA (Dec 28, 2008)

VentMedic said:


> My reference for ventilators on asthmatics was intended more for the hospital setting. The few EMS companies in the U.S. that do carry portable ventilators use ones that are more the ATV model and I would NOT trust any acute asthmatic to be placed on one unless the provider was an RRT with some experience. Although hand bagging has its own risks also.
> 
> Some Paramedics with flight and CCT do have access to more sophisticated technology but the brief overview some get in a "CCEMT-P or CCT" course barely covers the "knobology" part. I would just be happy if some would put a bacteria filter at the inspiratory flow outlet to protect the patients they pick up or bring to our hospital. Even using an HME/filter at the airway to protect the providers is too much to a ask of some.
> 
> ...



As was my reference. In ambulance here we are only just trialling a "CPAP" device called "whisperflow" for use with several categories of respiratory pts.
MICA types used oxylogs some years ago but they were withdrawn for cost issues and because the particular (anitquated) model we used had no alarms if the pt became disconnected from the system.

Even our whisperflow device has a thick OH&S angle to it - we have been *****ing for years about standing up behind APO pts eg manually ventilating them (with PEEP - I'm cringeing to describe it that way) in the back of a moving truck with the cumbersome closed circuit O2 device we carry - murder on your back and not so good if your ambulance happens to crash.

Personally I've been railing for fixed wall mounted ventilation equipment to become standard in our trucks for a long time to no avail.

On CPAP, at least in the LVF/APO pt I was doing my clinicals during my MICA course back in the early nineties when the ED director there showed me the "new" management of APO using NIV CPAP rigs.

And yet as of 2008 we are still using BVM and cheap basic throw away CPAP devices on our MICA trucks. Still, even at this basic level I gain heart from seeing APO, pneumonia and COPD patients arrive at ED far better than they were at home near death.

Our ED docs often quip after an APO pt comes in with SPO2 99% (from 88% at home) pink warm dry with a good BP, lasix/GTN on board, no pain etc that "we don't have to do anything - you've done it all for us" - not exactly right but it makes you feel useful - and the pt isn't suffering as they were.

Ambulance is the last to evolve and I think it takes along time for ambos themselves to convince the professional medical community that we can be trusted to take the next step. I remain convinced more advanced ventilation optins will become standard to ambulance in the future once education, cost and other issues are handled.

Your insights are much appreciated as always. I hope the boys and girls on the forum realise what a valuable tool it is for all our further educations when such quality posters are present.

Keep up the great posts and don't stop putting us in our places when we get too cocky!

As a final thought for readers - my favourite analogy is this. 

Medicine can be viewed as the Ross Ice Shelf in the antarctic - vast, seemingly endless. 

The greatest world renowned medical specialist alive is a giant iceberg floating in it. Impressive-standing out but still humble by the scale of the ice flow as a whole.

Your average doc is a modest but still impressive one - there are many of them all different sizes and shapes. 

The ice flow constantly moves. grows, changes - it's never the same.

As for the average ambo - he is an ice cube - still part of the ice pack, important and unique and helping to keep it together but yet to absorb more ice as the world of medicine melts and helps the ice cube to grow. 


MM

 PS  (Lets hope global warming doesn't spoil our growth!!!!)


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## piranah (Jan 8, 2009)

in my state AKA Rhode Island, using the CPAP system is a basic skill due to the good that can be done with CHF,COPD...etc. I have not used it yet myself but have talked to many people about the good they can do, as far as "keeping them off the tube"...because honestly by keeping these pts "off the tube" we are potentially preventing a dependency on the ETT....a lot to learn here and I thank everyone for putting their ideas in and possibly giving me and other new medics a new insight to the thought of NIV....


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## Granola EMT (Feb 8, 2009)

We just started training for the Autovent. I found a lot of good information here! Not sure when we will put them into service yet, though...


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