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

- Rogue Medic

If We Are Not Competent With Direct Laryngoscopy, We Should Just Say So – Part II


Continuing from Part I of a paper that could, at best, be described as a convenience sample, since a quarter of patients were excluded from randomization because of attending physician bias.

What were the authors assuming when comparing GVL (GlideScope Video Laryngoscope) with DL (Direct Laryngoscopy) for intubation?

Intuitively, devices such as the indirect video laryngoscope should improve intubation performance. As such, this study tested the hypothesis that achieving better visualization during the intubation with the GlideScope Video Laryngoscope would result in a better airway management performance as measured by shorter intubation times.[1]


The authors also intuitively assume that shorter intubation times mean better airway management. This suggests that speed is the most important factor in airway management.

Image credit.

They are probably still preaching the myth of the Golden Hour at Shock Trauma.

Is speed more important than quality?

There is an excellent assessment of intubation attempt in this paper.

Confirmation of intubation attempt duration and success was identified using closed-circuit video.[1]


We should not be relying on self-reported intubation success, unless we aren’t interested in a study of fiction. We do not accurately report intubation success, so an objective measurement of success is essential. This should be applied to EMS, as well.

The failed intubation rate was less than 0.5%, but the participants had already excluded over a quarter of the patients, so how impressive is a half a percent failure on 3/4 of patients?

What is the success rate for all patients?

For all of the statistics regarding study measures, a p < 0.05 was chosen as the threshold for determining significance.[1]


Secondary outcome measures are free shots at finding something “significant,” so they should be required to achieve a higher standard than the 1 in 20 p value of < 0.05.[2]


To account for any potential bias from patients not enrolled owing to attending discretion, comparison analysis was performed between the eligible, enrolled patients and the eligible, nonenrolled patients. The data demonstrates that all groups were proportionally similar in their demographics, injury mechanism, ISS, and arrival vital signs (data not shown).[1]


And, according to Dr. Newman in the SMART EM podcast, the Mallampati scores of the excluded patients were similar to those of the included patients.

Used alone, the Mallampati tests have limited accuracy for predicting the difficult airway and thus are not useful screening tests.[3]


We conclude that the prognostic value of the modified Mallampati score was worse than that estimated by previous meta-analyses. Our assessment shows that the modified Mallampati score is inadequate as a stand-alone test of a difficult laryngoscopy or tracheal intubation, but it may well be a part of a multivariate model for the prediction of a difficult tracheal intubation.[4]


Do the demographics, injury mechanism, ISS, and arrival vital signs increase the ability of the Mallapati to predicting difficult intubation?

Image credit.

How do we know that the difficulty was similar between included patients and excluded patients?

Similar Mallampati scores.

How useful are Mallampati scores at predicting difficulty of intubation?

The pooled estimates demonstrated that only 35% of the patients, who underwent tracheal intubation with difficulties, were correctly identified with a modified Mallampati test.[4]


Does the Mallampati score work well for predicting difficulty of intubation with a video laryngoscope?

The clinical use of videolaryngoscopes may change the accuracy of predictors of difficult tracheal intubation and require a different definition of difficult tracheal intubation.[4]


The Mallampati score does not appear to be of much use in comparing the excluded patients from the included patients, but that is what the authors use to assure us that the patients are similar.

Mallampati scores compare one aspect of visibility, but how important is visibility for intubation?

To be continued in Part III.


[1] Effect of video laryngoscopy on trauma patient survival: a randomized controlled trial.
Yeatts DJ, Dutton RP, Hu PF, Chang YW, Brown CH, Chen H, Grissom TE, Kufera JA, Scalea TM.
J Trauma Acute Care Surg. 2013 Aug;75(2):212-9. doi: 10.1097/TA.0b013e318293103d.
PMID: 23823612 [PubMed – in process]

[2] Do multiple outcome measures require p-value adjustment?
Feise RJ.
BMC Med Res Methodol. 2002 Jun 17;2:8. Review.
PMID: 12069695 [PubMed – indexed for MEDLINE]

Free Full Text from BioMed Central.

Standard scientific practice, which is entirely arbitrary, commonly establishes a cutoff point to distinguish statistical significance from non-significance at 0.05. By definition, this means that one test in 20 will appear to be significant when it is really coincidental. When more than one test is used, the chance of finding at least one test statistically significant due to chance and incorrectly declaring a difference increases. When 10 statistically independent tests are performed, the chance of at least one test being significant is no longer 0.05, but 0.40.


[3] A systematic review (meta-analysis) of the accuracy of the Mallampati tests to predict the difficult airway.
Lee A, Fan LT, Gin T, Karmakar MK, Ngan Kee WD.
Anesth Analg. 2006 Jun;102(6):1867-78.
PMID: 16717341 [PubMed – indexed for MEDLINE]

[4] Poor prognostic value of the modified Mallampati score: a meta-analysis involving 177 088 patients.
Lundstrøm LH, Vester-Andersen M, Møller AM, Charuluxananan S, L’hermite J, Wetterslev J; Danish Anaesthesia Database.
Br J Anaesth. 2011 Nov;107(5):659-67. doi: 10.1093/bja/aer292. Epub 2011 Sep 26.
PMID: 21948956 [PubMed – indexed for MEDLINE]

Free Full Text from Oxford Journals.

Yeatts DJ, Dutton RP, Hu PF, Chang YW, Brown CH, Chen H, Grissom TE, Kufera JA, & Scalea TM (2013). Effect of video laryngoscopy on trauma patient survival: a randomized controlled trial. The journal of trauma and acute care surgery, 75 (2), 212-9 PMID: 23823612

Lee A, Fan LT, Gin T, Karmakar MK, & Ngan Kee WD (2006). A systematic review (meta-analysis) of the accuracy of the Mallampati tests to predict the difficult airway. Anesthesia and analgesia, 102 (6), 1867-78 PMID: 16717341

Lundstrøm LH, Vester-Andersen M, Møller AM, Charuluxananan S, L’hermite J, Wetterslev J, & Danish Anaesthesia Database (2011). Poor prognostic value of the modified Mallampati score: a meta-analysis involving 177 088 patients. British journal of anaesthesia, 107 (5), 659-67 PMID: 21948956


Comment on If We Are Not Competent With Direct Laryngoscopy, We Should Just Say So – Part I


In the comments to If We Are Not Competent With Direct Laryngoscopy, We Should Just Say So – Part I, TexasMedicJMB writes the following –

I look at the approach of what works for the person performing the intubation is best.



What is best for the patient is what is best.

Research to find out what is best for the patient is important.

The goal isn’t to satisfy keeping a low-tech approach, the goal is to maximize patient care.


That is why we need research.

We can’t just assume that we know what is best without valid evidence. If we are honest about doing what is best for our patients and if we are to behave ethically, we need to find out what is best for our patients.

If a difficult airway is encountered and the decision to use a Bougie (flex-tube introducer) is made does this qualify as witchcraft?


That depends.

What do I mean by witchcraft?

By witchcraft, I mean treatments that are based on superstition, wishful thinking, and/or anecdote, rather than valid evidence.

Is the decision to use a bougie based on valid evidence?

If not, then the decision may qualify as witchcraft, as I use the term.


However, you entirely missed the point of my criticism of the opposition to learning by these anesthesiologists.

These witches anesthesiologists refused to participate in research designed to answer a question that has not yet been answered and may affect patient survival.

If an anesthesiologist opts to use a Mac 0 on a pediatric pt rather than a text-book suggested Miller 0 is this witchcraft?


The textbook recommendation appears to be witchcraft, but feel free to provide valid evidence to support either opinion.

If the doctor opts to use VGL because the pt is perceived difficult due to morbid obesity, known CA tumor, etc. why is this witchcraft?
I call it prudent judgement.


Is there valid evidence that the GVL (GlideScope Video Laryngoscope) improves outcomes?

If not, then what you describe is not prudent judgement, but mere wishful thinking and therefore witchcraft, as I use the term.

From the article at http://www.ncbi.nlm.nih.gov/pubmed/22042705: Compared to direct laryngoscopy, Glidescope(®) video-laryngoscopy is associated with improved glottic visualization, particularly in patients with potential or simulated difficult airway.


That is great for someone selling video laryngoscopes

These are only surrogate endpoints, which do not matter.

Surrogate endpoints are just hypothesis generators for studies that will determine if the video laryngoscope actually improves outcomes that matter.

Surrogate endpoints are excellent for self-deception.

Where is the evidence of improved outcomes that matter?

From http://ccforum.com/content/17/5/R237: In the medical ICU, video laryngoscopy resulted in higher first attempt and ultimate intubation success rates and improved grade of laryngoscopic view while reducing the esophageal intubation rate compared to direct laryngoscopy.


Where is the evidence of improved outcomes that matter?

According to the paper I am writing about,[1] video laryngoscopy resulted in longer intubation attempts and dramatically more hypoxia.

Are we curing the disease, but killing the patient?

Blood-letting also improved surrogate endpoints, while it increased the likelihood of death for patients treated with blood-letting.

Physicians observed of old, and continued to observe for many centuries, the following facts concerning blood-letting.

1. It gave relief to pain. . . . .

2. It diminished swelling. . . . .

3. It diminished local redness or congestion. . . . .

4. For a short time after bleeding, either local or general, abnormal heat was sensibly diminished.

5. After bleeding, spasms ceased, . . . .

6. If the blood could be made to run, patients were roused up suddenly from the apparent death of coma. (This was puzzling to those who regarded spasm and paralysis as opposite states; but it showed the catholic applicability of the remedy.)

7. Natural (wrongly termed ” accidental”) hacmorrhages were observed sometimes to end disease. . . . .

8. . . . venesection would cause hamorrhages to cease.[2]


I am sorry that your child died, but we consider surrogate endpoints to be more important than the lives of our patients.

This paper could have helped to answer that question, but a bunch of anesthesiologists witches decided that they just know and they don’t care about reality or outcomes. In other words, surrogate endpoints are more important than the lives of their patients.

As you point out, the article you linked just leaves the sub-group in question at “discretion, unspecified”.



As Dr. David Newman stated in the podcast,[3] he contacted the corresponding author and was told that all of the attending physician discretion, unspecified patients were because there are some anesthesiologists who refuse to use anything other than a video laryngoscope.

In other words, their patient care depends on prejudice – as does witchcraft.

Is the discretion the witchcraft and psychics? Maybe. Is it likely these pt’s were indeed difficult airways the physician felt more comfortable using VGL?


Again, according to Dr. Newman, some anesthesiologists insisted on intubating all of their patients with video laryngoscopes, regardless of difficulty. They consider themselves too smart to learn, so they refused to participate.

Is the physician truly practicing witchcraft because he chose to perform a procedure known to lower time to intubation, improve first-pass success, etc?


Does lowering intubation time improve outcomes?

If video laryngoscopes shorten intubation time, then why did it take longer to intubate patients with the video laryngoscopes?

Valid research could help answer that.

Would it have been better if he’d have ignored the VGL device and made several attempts at DL to pass the ETT?


Why do you assume that would be the outcome?

Do you have any valid evidence?

One thing this paper does make clear is that there is no good reason to assume that use of video laryngoscopes improve outcomes.

The usage of VGL doesn’t appear to be a tool of witchcraft. This is evolution of medicine.


You appear to be defending the preventable deaths of patients in order to promote the continuing expansion of witchcraft in medicine.

We do not know what is best, but the anesthesiologists are defending their opinions and protecting their opinions from evidence that may contradict those opinions.

That is witchcraft superstitious nonsense.


[1] Effect of video laryngoscopy on trauma patient survival: a randomized controlled trial.
Yeatts DJ, Dutton RP, Hu PF, Chang YW, Brown CH, Chen H, Grissom TE, Kufera JA, Scalea TM.
J Trauma Acute Care Surg. 2013 Aug;75(2):212-9. doi: 10.1097/TA.0b013e318293103d.
PMID: 23823612 [PubMed – in process]

[2] Blood-Letting
Br Med J.
1871 March 18; 1(533): 283–291.
PMCID: PMC2260507

[3] SMART Literature Update
SMART EM podcast
Friday, October 11, 2013
Dr. David Newman and Dr. Ashley Shreves
From about 45:45 to 1:11:00 in the podcast is on this paper.
Podcast page.


If We Are Not Competent With Direct Laryngoscopy, We Should Just Say So – Part I


This study starts out looking good, but there is a huge problem with the design.

If the person intubating felt that he needed to use the video laryngoscope to get the tube, then the patient was not randomize into the study.

How was this paper accepted for publication with such an obviously violation of research methodology?

Did the authors at least track the violations of ethics, so that some analysis of all patients could be attempted?

Maybe this is not really GVL (GlideScope Video Laryngoscope) vs. DL (Direct Laryngoscopy), but a comparison of intubation of the not-so-difficult airway with GVL vs. DL.

What is not-so-difficult? Whatever did not get the doctor to cry, I could not possibly manage that airway safely with a regular laryngoscope!

833 patients would have been randomized, but the person in charge of the airway cried uncle in 210 (just over 25%) of these cases.

Image credit.[1]

Has airway management really deteriorated to the point where doctors do not feel competent managing 25% of airways without an electronic toy because they are superstitious and believe the toy has magical powers?



A study could be set up with some sort of objective criteria for excluding the most difficult airways and still be valid, but how do we objectively assess the need for an electric rabbit’s foot?

Did the doctors read their horoscopes and determine that it was a bad day and they needed to use all of their voodoo powers that day?

Did the doctors consult with psychics?

We do not know, because the criteria for superstition are not explained.

This is just a reminder that medicine, and perhaps especially trauma medicine, is still a very superstitious field. It wasn’t that long ago that these patients would have been treated with blood-letting to get rid of the bad humors that prevent healing. Humorous medicine.

Dr. David Newman and Dr. Ashley Shreves describe this in a SMART EM podcast.[2] Dr. Newman corresponded with one of the authors and states that some of the anesthesiologists at Shock Trauma are biased in favor of the video laryngoscope and refuse to use anything else. Were the 210 patients excluded just because some attending anesthesiologists are too biased to learn what works and those anesthesiologists were just throwing a tantrum for all of their patients?

The mythology of I know it works because I’ve seen it work.[3]

Are 25% of the attending anesthesiologists at Shock Trauma too biased to learn?[4]

Or have we improved to the point where only 25% of attending physicians in a specialty are to biased to learn?

To be continued in Part II.


Image credit for witch’s hat.

[1] Effect of video laryngoscopy on trauma patient survival: a randomized controlled trial.
Yeatts DJ, Dutton RP, Hu PF, Chang YW, Brown CH, Chen H, Grissom TE, Kufera JA, Scalea TM.
J Trauma Acute Care Surg. 2013 Aug;75(2):212-9. doi: 10.1097/TA.0b013e318293103d.
PMID: 23823612 [PubMed – in process]

[2] SMART Literature Update
SMART EM podcast
Friday, October 11, 2013
Dr. David Newman and Dr. Ashley Shreves
From about 45:45 to 1:11:00 in the podcast is on this paper.
Podcast page.

[3] I’ve Seen It Work and Other Lies
Tue, 21 Jun 2011
Rogue Medic

[4] It would be the anesthesiologists managing just over 25% of the intubations, rather than 25% of the anesthesiologists, but no information is provided to clarify how many anesthesiologists that would be.

The result of the bias affects just over 25% of patients.

Yeatts DJ, Dutton RP, Hu PF, Chang YW, Brown CH, Chen H, Grissom TE, Kufera JA, & Scalea TM (2013). Effect of video laryngoscopy on trauma patient survival: a randomized controlled trial. The journal of trauma and acute care surgery, 75 (2), 212-9 PMID: 23823612


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


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]


[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

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.


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.


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.


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.


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.


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


Will IV Oxygen Save Lives?

Image credit.

Intravenous oxygen delivery that works?

Maybe temporary oxygenation, but not yet.

Will this change the approach to CICV (Can’t Intubate, Can’t Ventilate) patients?

No, but it may change the approach to CICO (Can’t Intubate, Can’t Oxygenate) patients.

The distinction is important. If we can deliver oxygen without ventilation, we can avoid some of the problems of hypoxia, but we will still have to deal with the acidosis that results from the inability to eliminate CO2 (Carbon DiOxide).

In the early 1900s, intravenous administration of oxygen gas was used in attempts to relieve refractory cyanosis (4–7). Most reported that spontaneously breathing, cyanotic animals exhibited signs of pulmonary embolism at infusion rates in excess of 0.2 to 1 ml/kg per minute and required frequent pauses in the infusion (4, 5); . . . None of these studies documented an increase in oxygen content in the blood as a result of the intervention.[1]


Try walking up several flights of stairs while only breathing through your nose. You will become short of breath very quickly.

Unless you are in truly horrible shape, it is not a lack of oxygen that is causing you to become short of breath. It is the inability to remove CO2 (Carbon DiOxide) that is the problem.

Most of us breathe because of a buildup of CO2, not because of a lack of oxygen.

The reflexive response of some people might be to give the anti-acidosis drug NaHCO3 (sodium bicarbonate). We will ignore the sodium, which at 5.8% in NaHCO3 is over 6 times the concentration of the NSS (Normal Saline Solution – 0.9% sodium) we routinely give. The sodium in NaHCO3 may be effective for treating sodium channel blocking drugs, such as antidepressnts, antiseizure medications, antiarrhythmics, and antivirals.[2]

The sodium is not the real danger. The bicarbonate (HCO3) is the problem. When binding with the excess hydrogen ions to neutralize metabolic acidosis, CO2 is produced.

HCO3 + H+


CO2 + H2O

a patient with complex airway anatomy and difficulty maintaining oxygenation using basic airway maneuvers could avert a hypoxemic crisis during a prolonged intubation attempt. To date, safe and effective intravascular delivery of oxygen gas has not been realized.[1]


In the cute little bunnies used in the study (7 LOM [Lipidic Oxygen–containing Microparticles] and 6 Control), these were the results.

Click on images to make them larger.

Oxygen saturation remained between 40% and 60% with the LOM, but that was much better than the less than 20% for the controls. since the study animals received LOMs titrated to an arterial oxygen tension of greater than 30 mmHg, this is not a surprise. The controls just received fluid at a similar rate.


CO2 more than doubled for both groups.

Providing oxygen does nothing to remove CO2.


When CO2 increases, the pH will decrease (acidosis will increase).

Sodium bicarbonate will not decrease the acidosis for these patients.

Sodium bicarbonate will increase the acidosis for these patients.

Sodium bicarbonate produces CO2, which must be removed by ventilation. If we are giving LOM to patients we can adequately ventilate, maybe we do not understand what we are doing.

We should only give sodium bicarbonate to a patient who is well ventilated – unless we are trying to kill the patient.


In (F) and (G), data are means ±SEM. The blue lines end at 10.2 min because no animals treated as controls had spontaneous circulation after that time and received chest compression–only cardiopulmonary resuscitation (CPR) during the remainder of asphyxia. (H) Kaplan-Meier plot of animals experiencing cardiac arrest during asphyxia (left; P =0.0002, log-rank test), restoration of mechanical ventilation (shaded box), and subsequent recovery and observation (right).[1]



None of the bunnies reported any near-death experiences.

Consider the time involved. Many in the media have been reporting this as a way to provide half an hour of apneic oxygenation. That is ridiculously optimistic. This will be something that might provide an extra 5-10 minutes to manage a hypoxic patient, if the patient has not already died due to the hypoxia.

5-10 minutes can be the difference between life and death.

Don’t believe me?

Hold your breath for 10 minutes. Just stop breathing and hold your breath.[3]

Without LOMs, all of the bunnies were pulseless after a little more than 10 minutes, but at 15 minutes, when ventilation was resumed, almost all of the LOM bunnies still had pulses (6 out of 7).

LOMs are not just to make it possible to deliver a patient with a pulse to the hospital, so that we can say that They didn’t die in the ambulance.

That is not changing anything.

LOMs are to provide time for us to provide an airway – if this ever demonstrates safety and efficacy in humans.


[1] Oxygen gas-filled microparticles provide intravenous oxygen delivery.
Kheir JN, Scharp LA, Borden MA, Swanson EJ, Loxley A, Reese JH, Black KJ, Velazquez LA, Thomson LM, Walsh BK, Mullen KE, Graham DA, Lawlor MW, Brugnara C, Bell DC, McGowan FX Jr.
Sci Transl Med. 2012 Jun 27;4(140):140ra88. doi: 10.1126/scitranslmed.3003679.
PMID: 22745438 [PubMed – indexed for MEDLINE]

Free Full Text Download in PDF format from medlive.cn

At the end of the asphyxial period, mechanical ventilation was restored with 100% oxygen until return of pulsations (in animals receiving chest compressions) and then titrated downward to achieve arterial saturations of >92%. Animals achieving return of spontaneous circulation after relief of asphyxia were treated with standard intensive care management, including inotropic support (dopamine, 2 to 10 mg/kg per minute, intravenous infusion) to maintain MABP of at least 40 mmHg during the follow-up period. Hyperthermia was avoided by passive ambient cooling (goal, 34 to 35° C). Animals were sacrificed 90 min after the end of asphyxia for lab and histology sampling.

Everyone seems to be using therapeutic hypothermia and trying to avoid giving too much oxygen.

[2] Management of sodium-channel blocker poisoning: the role of hypertonic sodium salts.
Di Grande A, Giuffrida C, Narbone G, Le Moli C, Nigro F, Di Mauro A, Pirrone G, Tabita V, Alongi B.
Eur Rev Med Pharmacol Sci. 2010 Jan;14(1):25-30. Review.
PMID: 20184086 [PubMed – indexed for MEDLINE]

Free Full Text in PDF format from EuropeanReview.org

As more substances having sodium-channel blocking properties become available, the incidence of this poisoning may be expected to increase, and clinician, particularly the emergency physician, should be familiar with this potential fatal condition.

A little evidence supports the treatment with hypertonic sodium salts, and current recommendations have not been based on randomized clinical trials.

[3] Longest time breath held voluntarily (male)
Guinness World Records
Web page.

The longest time holding the breath underwater was 22 min 00 sec by Stig Severinsen (Denmark) at the London School of Diving in London, UK, on 3 May 2012.

Stig was allowed to hyperventilate with oxygen prior to the attempt, and did this for 19 minutes and 30 seconds.

Kheir, J., Scharp, L., Borden, M., Swanson, E., Loxley, A., Reese, J., Black, K., Velazquez, L., Thomson, L., Walsh, B., Mullen, K., Graham, D., Lawlor, M., Brugnara, C., Bell, D., & McGowan, F. (2012). Oxygen Gas-Filled Microparticles Provide Intravenous Oxygen Delivery Science Translational Medicine, 4 (140), 140-140 DOI: 10.1126/scitranslmed.3003679


Bougies and ALS Airways


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?


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.





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.


[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

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

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