Without evidence of benefit, an intervention should not be presumed to be beneficial or safe.

- Rogue Medic

Factors associated with failed intubation attempts in the ED – Difficult Airway

ResearchBlogging.org
 

As with any procedure, each attempt at intubation increases the chance of harm to the patient.

What can we do to minimize the possibility of making more than one attempt at intubation?
 

The aim of this study was to identify factors associated with successful second and third attempts in adults following a failed first intubation attempt to support an effective rescue attempts strategy in the ED.[1]

 

Click on images to make them larger.
 

The success rate for each attempt was about 80% for the first, second, and third attempts. Several factors seem to have influenced that success rate, but the most important appears to have been the presence of a difficult airway.
 

The 6 academic EDs were equipped with core airway devices and drugs, one or more extraglottic devices, one or more video laryngoscopes and fiberscopes, RSI drugs, and one or more cricothyrotomy sets or kits.[1]

 

All intubations were supervised by a senior physician, so they should be well prepared for difficult airways.
 

A difficult airway was defined as a case in which the first intubator anticipated the difficult airway considering 3 dimensions of difficulty: difficult laryngoscopy and intubation, difficult bag-mask ventilation, and difficult cricothyrotomy.[1]

 

In the discussion, the authors suggest that they may have come up with higher rates of difficult airways for the first intubation attempt due to using three criteria to identify difficult airways.

This should not suggest that their conclusions about difficult airways are weakened. The opposite is more. They were less likely to miss a difficult airway. Difficult bag-mask ventilation may not be predictive of a difficult airway, but the increasing proportion of difficult airways among the failed intubations suggests that these airways were difficult.
 


 

Perhaps if we view the difficult airways as a proportion of the successes and failures of each intubation attempt, it will make things more clear.
 


 

Only 26.3% of first intubation attempt failures, but 36.5% of second intubation attempt failures, and increasing dramatically to 64% of third intubation attempt failures.

This does raise the question of why 36% of third intubation attempt failures were not considered difficult intubations?

Were they only going by the initial assessment of difficult intubation?

Shouldn’t we be reevaluating as we get further information as the Reverend Thomas Bayes advises?[2]

Footnotes:

[1] Factors associated with successful second and third intubation attempts in the ED.
Kim JH, Kim YM, Choi HJ, Je SM, Kim E; on behalf of the Korean Emergency Airway Management Registry (KEAMR) Investigators.
Am J Emerg Med. 2013 Jul 29. doi:pii: S0735-6757(13)00395-1. 10.1016/j.ajem.2013.06.018. [Epub ahead of print]
PMID: 23906622 [PubMed – as supplied by publisher]

[2] Bayesian inference
Wikipedia
Article

Kim JH, Kim YM, Choi HJ, Je SM, Kim E, & on behalf of the Korean Emergency Airway Management Registry (KEAMR) Investigators (2013). Factors associated with successful second and third intubation attempts in the ED. The American journal of emergency medicine PMID: 23906622

.

Airway Instruction – Episode 171 of the EMS EduCast

 

We want to be permitted to intubate.

True.

We don’t want to have to practice.

Sadly, that also appears to be true.

Fortunately for those of us who hate to practice, it is difficult to get paramedics time in the OR to practice on live people.

Not true.

Listen to Bill Toon, PhD/Paramedic explain how he was able to set up a system for all of the paramedics to rotate through the OR (Operating Room) to obtain practice and continuing education on real people.
 

Go listen to the podcast.
 


Image credit.
 

Bill Toon, Greg Friese, Rob Theriault, and David Blevins discuss ways of improving airway skills.
 

What if we do not work in a system that is set up like Johnson County Med-Act? Are we out of luck?

No, but we just have to work a bit harder to be good. Bill Toon did not accomplish this overnight, so do not despair that you do not have something already. Get to work on setting one up. It will take time, initiative, and the ability to ignore the people who say it cannot be done.

I would be surprised if Bill did not know some people who know some of the anesthesiologists where you would be trying to set this up. Talking to people who have done this and not been visited by plagues of blood, frogs, locusts, others, and the deaths of their firstborn might help to get them to at least consider trying this.

Do not expect things to happen immediately. That is one of the important lessons bill discusses in airway management.

Slow down!

Work on the skill and ignore the speed. After we have developed skill, then we can work on speed.

Speed without skill is dangerous, but that is the way many of us have been taught.

Panic about the amount of time it might take.

Hold your breath, and when you need to take a breath you may be too hypoxic to remember what you were doing.

Talk to a martial artist. They work on the skill first, then the speed.

Talk to someone who races motorcycles. They work on riding smoothly, then add the speed.
 

Even if you cannot set up a similar OR program, we can practice on mannequins, but most of us seem to lack the imagination and the understanding to put in the thousands of mannequin intubations that we should.

There are some excellent references provided as well.
 

Airway World The only virtual knowledge and collaboration center dedicated to airway management.

Airway Cam: Practical Solutions for Emergency Airways

Johnson County Med-Act

The Power of Video Recording from JAMA

 

Go listen to the podcast.
 

.

What Laryngoscope Blade Do You Use? – Why?


 

Which laryngoscope blade is your favorite?

Does length matter?

Does strength matter?[1]

Dr. Minh LeCong asks this at his blog PHARM – PreHospital And Retrieval Medicine.

There is also a video that provides some information on blade size.
 

[youtube]gYxwhEmYb9w[/youtube]
 

One of the problems with the video is the hand position. The laryngoscope should be held so that the hand is touching the blade. I prefer to have my ring finger touching the blade.

The higher the hand is on the handle, the more likely that the handle is used like a slot machine handle, as I demonstrate below.
 

[youtube]r2tQE61IGzo[/youtube]
 

The way to intubate is to position the patient before even picking up the laryngoscope (and premedicating with oxygen and whatever else is appropriate), then only advance the blade as far as necessary for each step of laryngoscopy.

1. Find the tongue.

Yay! That was easy.

2. Advance the laryngoscope and find the epiglottis.

Not as easy, but just more important.

3. Lift up (either in the valecula or under the epiglottis – it does not matter) and find the arytenoid structures. The vocal cords are above the arytenoid structures, so there is no need to lift up any farther.

4. Advance the bougie/tube over the arytenoid structures without touching anything else. It isn’t about cleanliness. The biggest problem I see people have when trying to intubate is that they do not avoid everything else in the mouth and end up trying to force the tube.

Force should never be used in the airway.

We should not arm wrestle with the airway. We will lose.

Go ahead and try to force this airway. I double dog dare you.
 


Image credit. It is all in the positioning.
 

The goal of airway management is to out-think the airway, not to out-muscle the airway.

As with martial arts, strength improves with repetition due to the development of muscle memory, even if there is no increase in strength. Technique requires a lot of repetition.

If you have not intubated a mannequin over a thousand times, you are still learning technique. We can always learn more.

We tend to be satisfied with very little practice, as if the patient owes it to us to inhale the tube.

This is ridiculous, but I find that for almost every class I have taught, I intubated the mannequin more times than everyone else in the class combined. I offer to let students practice as much as they want. I offer to help or to leave them alone.

Why is intubation of the airway of another human being so unimportant to so many of us?

Why do so many of us pretend that we are good at intubation?
 

Intubation shouldn’t be that hard, but research repeatedly shows us that we become airway stupid when things do not go as planned – and we are often the cause of the problems with our plan. Even if our plan is not just having the patient inhale the tube.
 

Most adults can be intubated with a #2 Mac or a #2 Miller. A longer blade is only necessary for a patient with an unusually long mandible.

Understanding of the airway is more important than blade size. Any spatula will do.

A blade should be relatively wide and flat. A tongue depressor would work well, but this would require some practice to manipulate the tongue with a tongue depressor. A tongue depressor is wider and flatter than a Miller, so a tongue depressor is better designed than a Miller to lift the tongue out of the way.

Why isn’t the Miller blade designed to lift the tongue out of the way? Was Miller in cahoots with the trial lawyers?

I prefer a Grandview, but a lower profile Grandview would be nice.
 

[youtube]xURQ12UAcMg[/youtube]
 

This is from Dr. Richard Levitan’s Airway Cam series.

Dr. Levitan is one of the top airway doctors in emergency medicine. Notice how low his hand is on the blade. It may be someone else manipulating the laryngoscope, but probably someone who has received input from Dr. Levitan on intubation technique.

The wrist is lower than the blade. This makes it more difficult to pull back on the blade and easier to lift up with the blade.

Intubation is not about a long blade, or a strong arm, or pulling back, but many people attempt to intubate using all three of these mistakes.

Intubation is about thinking, preparation, positioning, technique, and lifting the tongue up.

Footnotes:

[1] PHARM Poll : Blade choice in direct laryngoscopy – does length or strength matter?
by rfdsdoc
on May 2, 2013
PHARM – PreHospital And Retrieval Medicine
Article

.

Free Transport Ventilator Class from CentreLearn and Jim Hoffman This Thursday

 

Is this important if we do not do interfacility transport?

Yes.

Eventually, we will be using ventilators for almost everything where we currently use a BVM (Bag Valve Mask).

Why?

Because we humans are pathetic at bagging patients.

If you have not seen a doctor/nurse/respiratory therapist/paramedic/EMT basic bagging a patient at 60 breaths per minute, you have not been paying attention.

Since we seem to be resistant to education, the protocol writers are starting to make this something that is not corrected by education, but is prevented from happening by putting it in the hands of machines.

Needless to write, but this will have plenty of unintended consequences. The best way to avoid these unintended consequences (assuming that we do not magically develop excellent BVM skills, which would be the subject of other posts) is to be as familiar as possible with the use of transport ventilators and the kinds of problems that we can cause.
 

Original image credit.
 

The goal of medical care is to make things better, or to not make things worse.

The three most basic points, that apply just as much to BVM use as to ventilator use.

1. How to assess the patient for the cause of a sudden deterioration of the intubated patient. Everyone should know this. It is a part of every PALS/NRP class. If it is not, it was supposed to be. It should also be a part of every ACLS class, since these are some of the preventable causes of cardiac arrest.

DOPE – DOPE (or POET for the more politically correct) stands for Dislodged, Obstructed, Pneumothorax, Equipment failure. I have discussed these elsewhere.[1]

2. Hypotension – Even in a trauma patient, hypotension is often resolved by correcting the ventilation, rather than by adding fluid to the blood vessels.

3. Waveform Capnography – Continuous waveform capnography should be mandatory for the movement of all intubated patients anywhere. The same is true for extraglottic devices (LMAs, CombiTubes, King Airways, et cetera).

This is from CentreLearn and Jim Hoffman.
 

CentreLearn Webinar: Automatic Transport Ventilators in EMS
Thursday, April 25, 2013 8:30 PM – 9:30 PM EDT
 

Registrater here.
 

You will be connected to audio using your computer’s microphone and speakers (VoIP). A headset is recommended.

Or, you may select Use Telephone after joining the Webinar.
Toll: +1 (914) 339-0030
Access Code: 677-535-345
Audio PIN: Shown after joining the Webinar
Webinar ID: 799-127-985

System Requirements
PC-based attendees
Required: Windows® 7, Vista, XP or 2003 Server

Macintosh®-based attendees
Required: Mac OS® X 10.6 or newer

Mobile attendees
Required: iPhone®, iPad®, Android™ phone or Android tablet

Read our Audio Checklist for tips on using your computer’s microphone and speakers with GoToWebinar.

 

Registrater here.
 

Footnotes:

[1] Origins of the Dope Mnemonic
Wed, 26 Jan 2011
Rogue Medic
Article

[2] Death by hyperventilation: a common and life-threatening problem during cardiopulmonary resuscitation.
Aufderheide TP, Lurie KG.
Crit Care Med. 2004 Sep;32(9 Suppl):S345-51.
PMID: 15508657 [PubMed – indexed for MEDLINE]

Free Full Text Download in PDF format from burndoc.net.

[3] Capnography Use Saves Lives AND Money
Rogue Medic

Part I
Fri, 10 Dec 2010

Part II
Mon, 13 Dec 2010

Part III
Thu, 16 Dec 2010

Part IV
Thu, 16 Dec 2010

Part V
Tue, 04 Jan 2011

.

Bougies and ALS Airways

ResearchBlogging.org
 

The last paper we were working on for the EMS Research Podcast was this paper on the use of a bougie in the intubation of a simulated patient with spinal immobilization.

Is BAI (Bougie-Assisted Intubation) an improvement over traditional intubation (ETI or EndoTracheal Intubation)?
 

For this study, we had three separate hypotheses: The first was that BAI would be more successful than ETI in a difficult airway scenario; the second was that BAI would take no more time to complete than ETI in a difficult airway scenario; and the third was that BAI would be perceived by providers to be as easy to perform as traditional intubation.[1]

 

1. Better.

2. As fast.

3. As east to use.

That is a lot.
 

The study was done inconjunction with an annual skills competency assessment session. Each participant was being assessed for competence in nine different out-of-hospital procedural skills, and the study involved only one of the skill stations. The participants gave written consent to participate, but they were blinded to which skill was being assessed and what data were being obtained during the study. At the ETI station, a brief explanation and demonstration of BAI was given to each participant.[1]

 

An intubation mannequin had its neck strapped down to simulate motion restriction that would be consistent from intubation attempt to intubation attempt.

 

Before and during the study, three experienced emergency physicians verified that the best obtainable view by direct laryngoscopy was a partial glottis opening of approximately 20%—equivalent to a grade III Cormack and Lehane glottic view.[1]

 


Image credit.[2]
 

Grade III is a lovely view of the epiglottis, but that is as good as it gets with Grade III. A good view of the airway is going to involve a glimpse of arytenoid. More than that is just gratuitous. As with the rest of medicine, our goal is not to do as much as possible, regardless of the harm. Our goal is to do as little as possible, realizing that doing more often means doing more harm.

Since Cormack-Lehane Grade III means that the glottis is not visible, is it appropriate to call this a Grade III glottic view?
 

The participants were not aware that they were being timed. Timing began when the laryngoscope blade entered the mouth and ended with ventilation through the ETT with the BVM (evidence of successful ventilation as determined by manikin lung inflation or evidence of failed placement as determined by manikin stomach inflation).[1]

 

I do have problems with both of these.

Timing should begin when the last ventilation is delivered, rather than when the blade enters the mouth. The patient does not care why there is a delay in oxygen delivery, only that there is a delay in oxygen delivery. If we want to use hypoxia as a guide, then hypoxia also has nothing to do with when the blade enters the mouth.

The timing should end with successful ventilation either through a properly placed tube or through the BVM after recognizing incorrect placement. They did not record times for incorrectly placed tubes, but this information is relevant when dealing with real patients.

Also, is placement as easy to identify as with Fred The Head, where the lungs are visible? A requirement for a good assessment should be a part of the study. From the end of the paper, the reference to this method being similar to what could be done with the SimMan, suggests that this is Fred, or a close relative of Fred.
 

We found this model to be an easy and inexpensive way to provide EMS personnel with a difficult airway experience without the use of a high-fidelity simulator,[1]

 

This is not a criticism of Fred the Head or SimMan. We need to pay attention to what they are there for. They are there to assist us in creating a simulation of a real world environment, not to assist us in creating scenarios that are easy to measure. Their utility is that we can do both, when we address the reality of the simulation first. Otherwise, we begin to teach bad techniques.[3]

We can use low fidelity equipment to teach people to do the right thing, but we can also use high fidelity equipment to teach people to do the wrong thing. We need to understand what we are teaching.

Should we be teaching that time is not important if we do not place the tube between the cords?
 

Upon completion of the two techniques, each participant was asked to complete a five-point Likert-style survey to assess his or her overall ease of intubation with both techniques in this particular difficult airway model.[1]

 

How did the bougie do?
 

41% rated the ease of intubation the same for the two methods (asterisked values in Table 2), 50% rated the BAI to be easier than traditional ETI, and 9% rated traditional ETI to be easier than BAI. The participants perceived the BAI to be easier than traditional ETI in this difficult airway model (Jonckheere-Terpstra exact p = 0.0006).[1]

 

It is interesting that for a supposedly very difficult intubation, 16/35 participants (just under half) rate this simulated difficult airway as easy or as very easy.

There are many possible explanations, arrogance, excellence, not really very difficult, great airway education, et cetera.
 

3. As east to use?

Yes.
 

There was no significant difference in the average time to successful intubation (20.4 seconds for BAI [standard deviation (SD) = 9.1 seconds] versus 16.7 seconds for ETI [SD = 9.6 seconds], paired t-test p = 0.102). When controlling for order of techniques attempted, the difference between the groups remained nonsignificant (p = 0.0901). The analysis was limited to the 27 participants who were successful with both methods.[1]

 

This is one of the reasons that airway management should be seen as more complicated than just in the hole/not in the hole. The subjects who were least successful had their times eliminated from this comparison of times.

Does that bias the results?

I do not see how it can be considered as anything other than introducing a bias to the results.

Time from last ventilation to first ventilation is the time that matters. Whether the ventilation is through an endotracheal tube or a BVM is not as important as the ventilations.

If the tube is placed incorrectly, the amount of time until this is recognized does matter to the patient. This is one of the reasons why we should always listen over the stomach first.[4],[5]
 

2. As fast?

They did not come up with a statistically significant difference in times, but they only compared times when the subject was successful with both methods. Since almost all of the failures were when the bougie was not used, this would seem to preferentially eliminate the worst times for the traditional intubation.

The trend was toward a difference in favor of traditional intubation, but the method of time keeping had what appears to be a strong bias built in toward whichever method had the most failures.

The most failures turned out to be with the traditional intubation.

2. As fast?

There was no statistically significant difference in what was measured, but what was measured is not what should have been measured.

Maybe faster. Maybe as fast. Maybe slower. We do not know.
 

There was significantly greater success in intubating the simulated difficult airway with BAI than with ETI (94% vs. 77%, McNemar’s exact p = 0.0313). The order of techniques attempted did not influence this conclusion.[1]

 
94% success vs. 74% success.

If we are to continue using intubation, maybe we should use bougies all of the time.
 

1. Better?

Much better.
 
 

The problem with the bougie is that it is too long to be carried by EMS without bending it. Management tends not to approve of bending equipment that is not supposed to be bent. At 2 feet long, or longer, my excuse has been that the bougie is impractical in my gear.
 


 

This is the pocket bougie by Bomimed.

That will easily fit in my airway bag, or even a cargo pocket.

I have run out of excuses for not having a bougie with me.

I do not have any financial connections with anyone manufacturing or selling bougies. I just like the way this makes it much more practical for those of us in EMS to improve our intubation first pass success rates.

Dr. Scott Weingart (EMCrit) and Dr. Minh Le Cong (PHARM) have both covered the Pocket Bougie.

EMCrit.

PHARM.

 

[youtube]WDnDjfuh1Dc[/youtube]
 

Notice that when you use a bougie, you keep the laryngoscope in place until the tube is placed. Holding the bougie with the same hand that is holding the laryngoscope makes this an easy one person procedure.

Footnotes:

[1] Comparison of bougie-assisted intubation with traditional endotracheal intubation in a simulated difficult airway.
Messa MJ, Kupas DF, Dunham DL.
Prehosp Emerg Care. 2011 Jan-Mar;15(1):30-3. doi: 10.3109/10903127.2010.519821. Epub 2010 Nov 10.
PMID: 21067319 [PubMed – indexed for MEDLINE]

[2] Rapid airway access
Sérgio L. AmantéaI; Jefferson P. PivaII; Malba Inajá RodriguesIII; Francisco BrunoIV; Pedro Celiny R. GarciaV
Print version ISSN 0021-7557
J. Pediatr. (Rio J.) vol.79 suppl.2 Porto Alegre Nov. 2003
doi: 10.1590/S0021-75572003000800002
Free Full Text Article from Jornal de Pediatria.

[3] On Combat
by Lt. Col Dave Grossman (with Loren Christensen)
Chapter Two
Whatever is drilled in during training comes out the other end in combat–no more, no less

[4] Intubation Confirmation
Fri, 25 Apr 2008
Rogue Medic
Article

[5] More Intubation Confirmation
Sun, 27 Apr 2008
Rogue Medic
Article

Messa, M., Kupas, D., & Dunham, D. (2011). Comparison of Bougie-Assisted Intubation with Traditional Endotracheal Intubation in a Simulated Difficult Airway Prehospital Emergency Care, 15 (1), 30-33 DOI: 10.3109/10903127.2010.519821

.

Does Intubation Prevent Aspiration of Stomach Contents?

ResearchBlogging.org
 

This is a study that looked at the rate of aspiration among patients intubated in the PH (PreHospital or EMS) setting and compared them to patients intubated in the ED = (Emergency Department) setting.
 


Image credit.
 

There is one huge difference between these settings – EMS was not authorized to use any form of chemically assisted intubation or RSI (Rapid Sequence Induction/Intubation). At the time of this study, the only drugs available to snow the patient would have been morphine, midazolam (Versed) and/or diazepam (Valium).

One of the reasons for using RSI is to prevent aspiration. If the hurl muscles are paralyzed, will there be a technicolor yawn?
 

Tracheal aspirates were obtained using a standard Leukens trap as soon as endotracheal tube position was confirmed using visualization, auscultation, and end-tidal CO2. If no aspirate could be obtained, 3 mL of normal saline solution was instilled into the endotracheal tube. Each patient was ventilated for several breaths and the sample was then collected. Tracheal aspirates were collected and marked with a study number, and no further patient identifiers other than the study number were used after this point.[1]

 

This was a good way to make this unbiased, but I would have liked to see a repeat of the ED test about 15 and again at about 30 minutes after the original intubation. In Philadelphia, it would be reasonable to expect that the packaging and transport of patients would result in a similar time from intubation to sample collection. A review of the documented times could give a better estimate of the time from intubation to the time of the collection of the pepsin assay sample.

Would this difference in time from intubation to sample collection affect the results?

This is a variable that can be controlled for, so this variable should be controlled for.

How much is cost a factor?

I don’t know, but we draw conclusions from bunches of studies that have asterisks next to them to describe the variables that might have affected the results, when we should be drawing conclusions from much fewer studies that do not need these asterisks.
 

Of the 148 patients intubated in the ED, 33 (22%) had positive pepsin assays, as opposed to 10 (50%) of the 20 patients intubated in the PH setting (OR, 3.5; 95% CI, 1.34-9.08; χ2 P = .008). No patient was excluded owing to inability to obtain a tracheal aspirate.[1]

 

How many of the PH patients aspirated after the endotracheal tube was placed?

How many of the PH patients aspirated during the intubation?

How many of the PH patients aspirated before the intubation?

These are things we really want to know, because there are plenty of people who promote the myth that intubation prevents aspiration.

In a randomized study, with endotracheal tubes and extraglottic airways on the trucks on even days (or odd days), would the incidence of aspiration be lower with intubation or with only BVM ventilation?
 

It is important to note that there is no way of knowing whether the aspiration occurred immediately before, during, or after the actual act of ETI. However, it has been shown that pepsin’s activity in lung secretions diminishes over time, with pepsin testing losing much of its sensitivity after 30 to 60 minutes[14]. Thus, we can be fairly certain that the aspiration events occurred in the peri-intubation period.[1]

 

More than double the rate of aspiration of stomach contents with EMS intubation, but . . .

Would it be better without EMS intubation?

Would it be better with EMS intubation with RSI?

Would it be better with extraglottic airways?

We do not know.

A lot of people will claim that an extraglottic airway will not prevent aspiration, but . . .

Endotracheal tubes do not show any signs of preventing aspiration.
 

Although it is possible that the ETI skills of the paramedics were less than those of the ED staff, it is equally possible that the absence of adjunctive medications (such as RSI medications) may account for some, if not all, of the increase in aspiration rates in the PH setting.[1]

 

The number of PH intubations was very low, so this may be a statistical variation among a very low number of patients. The number of ED intubations was much larger and agrees with a larger study of ED intubations and aspiration performed by the same authors several years earlier.
 

Results: Tracheal aspirates were obtained from 225 patients. The pepsin assay was positive for aspiration in 57 of these patients (25.3%). Only 22 of these 57 patients (38.6%) were deemed definitely or likely to have aspirated by the intubating physician. Of the 105 patients thought unlikely or definitely not to have aspirated clinically, 21 patients (20%) tested positive for aspiration.[2]

 

How good is our opinion of whether aspiration is likely?

Horrible.

Even doctors, working in the much more controlled setting of the ED, do not recognize when aspiration is present or when aspiration is happening.

Even in the more ideal setting of the ED, intubation does not prevent aspiration.

Footnotes:

[1] Aspiration of gastric contents: association with prehospital intubation.
Ufberg JW, Bushra JS, Karras DJ, Satz WA, Kueppers F.
Am J Emerg Med. 2005 May;23(3):379-82.
PMID: 15915418 [PubMed – indexed for MEDLINE]

Free Full Text Download in PDF format from IEP.org.

[2] 128 Incidence of Aspiration after Emergency Endotracheal Intubation and Association with Clinical Suspicion
Joseph S Bushra, Jacob W Ufberg, David J Karras, Friedrich Kueppers;
Temple University School of Medicine: Philadelphia, PA
Academic Emergency Medicine 2002; 9:405. abstract issue

Free Full Text Download in PDF format from Academic Emergency Medicine

Ufberg, J., Bushra, J., Karras, D., Satz, W., & Kueppers, F. (2005). Aspiration of gastric contents: association with prehospital intubation The American Journal of Emergency Medicine, 23 (3), 379-382 DOI: 10.1016/j.ajem.2005.02.005

.

Paramedic School Accreditation – Advanced Airways vs. BVM


 

This week on EMS Office Hours, Jim Hoffman, Josh Knapp, John Broyles, and I discuss a few topics. National Registry of EMTs accreditation of paramedic schools.

Paramedic School Accreditation | Advanced Airways vs. BVM

If we are going to have standards, they should be based on some evidence that they work.

Is something better than nothing?

Something is only better than nothing if the something is something good.

Is a grade better than 80% good for bragging rights?

What does the grade mean? Does the exam demonstrate that the person understands good patient care? I do not see evidence that this initial exam does that.

The NR exam is just an initial exam, but some benighted people think that there should be higher pay for people who have passed this particular brand of entrance exam. Are they supposed to remain beginners forever?

Is a structured way of doing things a good way to evaluate people for the unstructured, or minimally structured, job of paramedic.

We also discuss what I wrote in Advanced Airway vs. BVM During CPR – Which is Worse?

There is no evidence that ventilations improve outcomes.

I was at Dr. Banerjee’s presentation on cardiac arrest and how their treatment protocol produces better outcomes than the rest of the country. One person in the audience kept complaining that he is wrong to not follow the ACLS guidelines because he will be sued. Dr. Banerjee’s response should be obvious – You need to show evidence of harm to win a law suit. I produce better outcomes than the rest of the country.

John Broyles brought up the way we educate badly with our focus on verbalizing Gloves on – Scene safe! and not thinking about what we are doing as far as using gloves and continually assessing scene safety.

Gloves are often inadequate BSI (Body Substance Isolation), but we act as if wearing gloves will protect against everything; as if wearing gloves somehow produces a force field around the body that protects parts of the body not covered by the gloves; as if gloves do not tear or break down and need to be replaced on the job; as if gloves make up for not cleaning our hands; as if touching clipboards and other equipment with gloves on is doing anything other than spreading germs all over the equipment that we will later pick up without gloves on; as if gloves need to be worn for every patient.
 


Guidance for the Selection and Use of Personal Protective Equipment (PPE) in Healthcare Settings
CDC (Centers for Disease Control and Prevention)
 

According to the CDC – Not every patient.

According to the CDC – Not every time.
 

Go listen to the podcast.

.

Advanced Airway vs. BVM During CPR – Which is Worse?

ResearchBlogging.org
 

The authors wanted to find out what method is worst best for ventilating patients during out-of-hospital treatment of cardiac arrest.

Endotracheal tube?

Supraglottic airway (laryngeal mask airway, laryngeal tube, and esophageal-tracheal twin-lumen airway device)?

BVM (Bag Valve Mask)?

This assumes that ventilations provide some sort of benefit to the patient. There is no evidence to support this myth.

Their endpoint was neurological outcome at one month for all out-of-hospital cardiac arrest patients treated January 1, 2005, to December 31, 2010.
 

In addition, we postulated that both advanced airway techniques (endotracheal intubation or use of supraglottic airways) would be similarly associated with favorable neurological outcome after OHCA.[1]

 

Intubation training required more intubations in the operating room than is required in the US (zero to ? – 5 are typically given as the minimum requirement, but there is no standard accepted by all agencies), or in the UK.
 

Beginning in 2004, endotracheal intubation could be performed by specially trained emergency lifesaving technicians who had completed an additional 62 hours of training sessions and performed 30 supervised successful intubations in operating rooms.24 [1]

 

What were the results?
 

 
Click on images to make them larger.

Everything underlined in red is worse than BVM and statistically significant. The endotracheal tube numbers underlined in blue are only statistically significant until adjusted for confounding variables and only for ROSC (Return Of Spontaneous Circulation).

ROSC is important – if we do not mind causing long term harm in order to get this short term benefit. This is not a trade off that helps our patients.
 

A set of potential confounders was chosen a priori based on biological plausibility and a priori knowledge. These selected variables included age, sex, cause of cardiac arrest, first documented rhythm, witnessed status, type of bystander CPR, use of a public access automated external defibrillator, epinephrine administration, and time intervals from receipt of call to CPR by EMS and from receipt of call to hospital arrival.[1]

 

Not adjusting for confounders would be wrong.

There is one big confounder that I will get to at the end.

The supraglottic airways did even worse than the endotracheal tubes. There has been research in pigs showing that the inflation of the cuffs of supraglottic airways cause more interruption of carotid circulation than the cuffs of endotracheal tubes and that the cuffs of endotracheal tubes cause more interruption of carotid circulation than BVMs. BVMs have no cuffs to inflate to limit carotid circulation, which is the main source of blood flow to the brain.[2]

What else does not have a cuff?

A nonrebreather mask doesn’t have a cuff.

A nasal cannula doesn’t have a cuff.
 

 

Did failed tubes cause the study to be biased against intubation?
 

However, we defined advanced airway management as successful endotracheal intubation or supraglottic airway placement only. Thus, in our study, failed advanced airway management cases reverted to and were classified as bag-valve-mask ventilation cases. This would have biased our conclusions toward the null.[1]

 

The authors also calculated the results if all of the missing BVM patient data were negative and all of the missing supraglottic airway data were positive. The supraglottic airway data were associated with so much harm, that even this did not make the results look much less harmful for use of supraglottic airways.

Likewise, the authors calculated the results if all of the missing BVM patient data were negative and all of the missing endotracheal tube data were positive. The endotracheal tube data were also associated with so much harm, that even this did not make the results look much less harmful for endotracheal intubation.

Only 6.5% of the patients had endotracheal intubation, so this seems as if we could be dealing with small numbers producing statistical flukes. However, 6.5% of this huge sample is still 41,972. Therefore, this is not a case of statistical manipulation of small numbers with no clinical significance. There are more intubated patients in this study than there are total patients in most studies of airway management.
 

Assuming the validity of our study, a more secure airway, regardless of its technique, would be detrimental.[1]

 

Should we assume the validity of this study?
 

In addition, multiple studies arrived at similar conclusions despite differing populations, disease groups, and designs.7-10,12,13 [1]

 

There are two problems.

1.

There is no group with no ventilations. I realize that this was not within the control of the authors, but it would answer a more important question.

We are asking –

What is the best method of ventilation during cardiac arrest?

We have not yet answered –

Should we be ventilating during cardiac arrest?

We have not determined that any ventilation is beneficial during cardiac arrest, but we are spending our time choosing colors and arguing over which brand name is best.

2.

14 minutes to ROSC vs. 6 minutes to ROSC?

This is only mentioned tangentially and I am not satisfied with the explanation.

This presents a lot of different data. They all are similar – right up until the very last one.
 

 

This deserves some very specific description.

Unfortunately, the data probably do not include enough information to learn more about these differences.

The difference in time to ROSC is huge.

The IQRs (InterQuartile Ranges) show much more diversity than we should expect when everything else is so similar.

Could this explain the difference in outcomes?

The explanation of the authors (that their subgroup analyses account for this) seems to be unreasonably optimistic.

I want the authors to show that patients who have ROSC in 6 minutes should not be expected to have an outcome that is three times better than patients who take 2 13 times as long to achieve ROSC.

These numbers are large huge. 281,522 in one group and 367,837 in the other. How can such a heterogeneous variable be given so little attention?

If I tell someone that two groups of patients were resuscitated, but it took over twice as long to resuscitate one group as it took for the patients in another group, should I expect anyone to be surprised that the group resuscitated faster has outcomes that are three times better?

In cardiac arrest, as time increases bad outcomes can be expected to increase at an even greater rate.

There is not even much overlap in the IQRs of the times to ROSC. 8 – 20 minutes vs. 3 – 12. A 12 minute IQR with only 4 minutes of overlap.

Although everything else appears to be well matched, I do not see the subgroup analyses reconciling the differences in ROSC times.

I think that this could adequately explain the differences in outcomes. We do need prospective studies, but we should find out if there is any reason to be providing ventilations in cardiac arrest (except for those that are pediatric and/or respiratory in origin).

See also Advanced Airway Loses to BVM and read the comments.

Footnotes:

[1] Association of prehospital advanced airway management with neurologic outcome and survival in patients with out-of-hospital cardiac arrest.
Hasegawa K, Hiraide A, Chang Y, Brown DF.
JAMA. 2013 Jan 16;309(3):257-66. doi: 10.1001/jama.2012.187612.
PMID: 23321764 [PubMed – indexed for MEDLINE]

[2] Impairment of carotid artery blood flow by supraglottic airway use in a swine model of cardiac arrest.
Segal N, Yannopoulos D, Mahoney BD, Frascone RJ, Matsuura T, Cowles CG, McKnite SH, Chase DG.
Resuscitation. 2012 Aug;83(8):1025-30. doi: 10.1016/j.resuscitation.2012.03.025. Epub 2012 Mar 28.
PMID: 22465807 [PubMed – in process]
 

CONCLUSION:
The use of 3 different SGDs (Supraglottic airway devices) during CPR significantly decreased CBF (carotid blood flow ) in a porcine model of cardiac arrest. While the current study is limited to pigs, the findings suggest that further research on the effects of SGD use in humans and the effects on carotid artery blood flow is warranted.

Hasegawa K, Hiraide A, Chang Y, & Brown DF (2013). Association of prehospital advanced airway management with neurologic outcome and survival in patients with out-of-hospital cardiac arrest. JAMA : the journal of the American Medical Association, 309 (3), 257-66 PMID: 23321764

Segal, N., Yannopoulos, D., Mahoney, B., Frascone, R., Matsuura, T., Cowles, C., McKnite, S., & Chase, D. (2012). Impairment of carotid artery blood flow by supraglottic airway use in a swine model of cardiac arrest Resuscitation, 83 (8), 1025-1030 DOI: 10.1016/j.resuscitation.2012.03.025

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