Advanced Airway Loses to BMV

Bag-Valve-Mask is better than ET Intubation or even supraglottic airways in cardiac arrest. Or at least that is the conclusion of an important new study, Association of Prehospital Advanced Airway Management With Neurologic Outcome and Survival in Patients With Out-of-Hospital Cardiac Arrest, just published in the January 16. 2013 issue of the Journal of the American Medical Association.

Abstract Available Here

The article again raises questions about the importance of ALS interventions in cardiac arrest, and makes us wonder if we are doing more harm than good with aggressive airway intervention.

I need to take a statistics class someday so I can better understand studies or at least make more sense of them, so I will leave others to comment on the technical points. Here are the results as I understand them:

The researchers looked at 649,654 consecutive out of hospital cardiac arrests in Japan over a six-year period (2005-2010). The primary end point was favorable neurological status one month after the arrest.

57% had bag-valve mask, 6% had endotracheal intubation and 37% had supraglottic airways.

Here is the outcome:

Neurologically Favorable Status
Overall 2.2%
Bag Valve – 2.9%
Supraglottic – 1.1%
ET – 1.0%

An accompanying editorial by noted airway researcher Hanry Wang and Donald Yealy called the study “large, methodically rigorous and compelling.”

The authors write:

“Recent studies have questioned the wisdom of the wide use of out-of-hospital endotracheal intubation in many severely ill or injured patients. Out-of-hospital endotracheal intubation adverse events include unrecognized esophageal placement, tube dislodgement, iatrogenic hypoxia and bradycardia, and frequent need for multiple tube insertion attempts. Endotracheal intubation during cardiac arrest can interfere with cardiopulmonary resuscitation continuity of chest compression or facilitate inadvertent hyperventilation, both of which can adversely influence cardiac arrest survival.”

I eagerly await responses more educated than mine to this study. At this point all I can do is speculate as to the reasons for this outcome based on commentary in the studies and my own thoughts.

Perhaps, while ET and supraglottic may be better airways the time taken to get them may come at the cost of effective CPR in the critical spare seconds patients have to be brought back from the precipice of permanent harm.

Perhaps while ET and supraglottic airways may save some patients, poor insertion may kill others who might have been saved.

Perhaps the supraglottic airways were more likely to be used in patients with a difficult airway (I don’t think this is true, but I was surprised and disappointed at the poor results of the supraglottic airways).

Perhaps, as the authors suggest, advanced airways may give the responders the avenue to kill the patients through hyperventilation and hyperoxemia.

I thought that perhaps the advanced airways were also accompanied by epinephrine, which has been shown to increase mortality, but then I saw in the study the use of epinephrine was evenly divided among the groups. The baseline characteristics of propensity-matched patients (whatever that means) were quite similar according to a large chart in the article.

I also thought that perhaps the bag value mask survivors included all those patients who were brought back by defibrillation before an advanced airway could even be inserted.

(I believe the paper says this is not the case due to statistical adjustments, but I don’t quite understand that. From the article: “endotracheal intubation and supraglottic airways were similarly associated with a decreased chance of favorable neurological outcome. The observed associations were large and persisted across different analytic assumptions.”)

The answers to some of these questions may lay in the study, but I await others to explain them to me.

In the meantime, I agree with the editorial writers conclusion that:

“The study by Hasegawa et al sends a clear message. Emergency medical services professionals across the world must engage in the scientific process. A large, well-designed research effort is needed to define the benefit from endotracheal intubation, supraglottic airway insertion, or more simple actions during resuscitation after cardiac arrest. Absent this investment, the emergency medical services community risks turning a blind eye and embracing ineffective or harmful airway interventions. Patients with cardiac arrest and the out-of-hospital rescuers who care for them deserve to know what is best.”

What do you think?

***

See Vince D’s excellent comments below. He also provided this link to the first expert commentary on the study:

MedPage Today Commentary

18 Comments

  • VinceD says:

    I’m a huge proponent of compression-only CPR, but I don’t think this study shows us what so many people claim. Of course I say this not having access to the full article, just having read the abstract, multiple commentaries, and similar articles.

    Here’s the rub, as taken from this commentary (http://www.medpagetoday.com/EmergencyMedicine/EmergencyMedicine/36857):

    “Ornato pointed out that a variable that could have affected the findings was the difference between the groups in the median time to a return of spontaneous circulation (14 minutes with advanced airway management versus 6 minutes with conventional ventilation).

    ‘It could very well be that the group of patients who restarted with a more prolonged resuscitation effort would in fact be expected to have less of a survival and a neurologically intact outcome,’ he said.”

    I’d have to see the full text to understand how the authors tried to control for that variable, but even with propensity-matching I doubt you can fully account for the effect of that giant difference in group characteristics.

    1) As you point out, patients with early ROSC don’t have time to get an advanced airway. That’s just a fact of resus logistics.
    2) It has been proven that patients who have longer down times have worse outcomes from cardiac arrest

    As a result, yes, there will always be an association between advanced airways and worse outcomes, but it’s only because of that third intermediate factor: duration of resuscitation.

    That is a factor that can only be controlled-for in a prospective, randomized trial, not registry data-dredging. You are right to be suspicious of this paper.

  • Dave B says:

    I fully agree with Vince…I addition, how do you account for different skill levels of rescuers? I agree that the less skilled the rescuers are in intubation, and code management in general, the more advanced airway maneuvers take away from good CPR and defib with minimal interruptions. Advanced airway techniques that do not sacrifice CPR and cause no additional interruptions to CPR should not be categorized the same as those efforts that bring the resuscitation efforts to a halt while the advanced airway techniques take place. IMHO, those two different scenarios are really different entities as far as this issue.

    • medicscribe says:

      Thanks for the comments Dave. Great airway management is undoubtedly good for the patient, but what percentage of poor airway management wipes out all the gains of great airway management. In other words, is Endotrachael intubation a skill that all paramedics should be doing or just a selected few? I have been intubating for twenty years, but my number of tubes is declining each year. The “if GCS is 8, intubate” mantra we used to have, we don’t follow anymore, plus with more medics on the road, and the availablity of alternative airways, I am lucky now to get only a few ETs a year.

  • Harold Zwanepol says:

    Here is a recent paper from Canada, http://www.ncbi.nlm.nih.gov/pubmed/23305613%20 showing that BLS use of the supraglottic airway IS beneficial. This study came from an EMS system with a strong airway management training program based on AIME (http://caep.ca/cpdcme/roadshows-current-cme/aime). Again, there is so much variation in EMS airway management training, that one wonders about interpretation of many of the studies. Even with continuous compressions, EMS systems with extended response and transport times require some form of airway/oxygen management, the body’s oxygen reserve is limited. Assured standards of airway management education would be a better focus of study.

    • medicscribe says:

      Thanks for the reference, harold, I will look into it. I believe strongly in the alternate airways, so was bvery discouraged by their poor performance in this study. It may have had to do with their use of the LMA as the primary backup as opposed to a combitube if i read the study right. It wasn’t very clear.

  • Allan says:

    I just read the full study. I have to say it appears exceptionally well done.

    The sample size makes it compelling.

    I might question it if it weren’t roughly in line with the results of many of the other studies we’ve seen over the past few years.

    • medicscribe says:

      Thanks for the comment, Allan. You are right it seems to mirror many recent studies. I just saw today that Journal Watch rated this paper as a Landmark paper. The emergency medicine editor for journal watch is Ron Walls, who is a noted airway expert, famous for his textbook and airway course.

      http://emergency-medicine.jwatch.org/cgi/content/full/2013/115/1

      Here is their explanation of a Landmark paper: From time to time, a study is published that is of such importance to physicians that it warrants special attention and should lead to an immediate reappraisal of a current practice or to the adoption of a new approach. When such articles are identified by the editorial boards of the Journal Watch publications, they will receive the designation “Landmark Article.”

  • Josh says:

    I found some interesting facts about Japanese paramedics:

    “In Japan, most paramedics have a firefighter background. The paramedic job requirements include a minimum of five years of employment as ambulance personnel, approximately 509 hours of lecture, and 406 hours of hospital training or simulation in a designated training facility. This represents a total of approximately 915 hours of training; however, on-the-job training with currently certified paramedics is not required. In addition, there is no system for relicensing or renewal in Japan, and continuing education is up to each individual.”

    So how can we take this study seriously? You cannot compare a paramedic in Japan to a paramedic in the US, UK, Canada etc. Our systems are all different, as is our training, and REQUIRED continuing education (which is not required in Japan). This study ONLY tells me the stats for Japanese paramedics. It’s time we start doing our own research in our own countries.

    • medicscribe says:

      I agree it is hard to compare, but it was interesting that the Japanesse paramedics had to do 30 OR intubations, 3X the US average before they could practice in the field.

      From the study: 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.

  • Neurologically Favorable Status
    Overall 2.2%
    Bag Valve – 2.9%
    Supraglottic – 1.1%
    ET – 1.0%

    Do I understand this correctly that the overall survival of the study patients was only 2.2%? That sucks. If that’s true, then the have a lot of other problems in their system.

  • Tanner says:

    The 2.2% really isn’t that bad. Most studies that I have read with higher survival rates show different end points. Some studies use ROSC, some use 24 hour favourable neurological status, and some use favourable neurological status at discharge. This one did 30 days later so of course the numbers will be lower.

    • medicscribe says:

      Interesting point. I think also they are including some seriously unrecoverable patients in their study as oppossed to systems that only count witnessed, bystander CPR in vfib and shocked within 5 minute codes.

  • Carrie says:

    The time to ROSC & training level of the paramedics has to be questioned before this study can be accepted, regardless of sample size. What is vital tho is that any advanced airway attempts must be carried out with minimal interruption to compressions (unless difficult airway I intubate without ceasing CPR as it seems to have minimal effect on my efforts), EtCO2 monitoring to detect appropriate placement, and strict adherence to ventilation rates to avoid hyper or hypoventilation (& regular training to ensure u can do it even when distracted & not handing off to less trained personnel). Does pose questions but I agree with the above comments – studies need to be performed in countries with highly trained officers.

    • medicscribe says:

      Again, the Japanese medics seem to have had higher training standards than we do in the US. As far as how they performed in the field, I am sure some were excellent, and some were horrible, just like in the US. I do wonder with ET if the few bad intubators don’t wreck enough havoac to wipe out the success of the best ones.

  • Cindi says:

    All I can add is this: I was required to do my intubation training early in medic school, did 19 of them and then never was required to do another until the first attempt in the field. During my internship I had the opportunity to witness very few attempts and all were jealously guarded by the ALS personnel working the codes. I have over the last 2 years made several attempts to go back to surgery and do more intubation practice with the CNAs but was told the mannequin was good enough. I don’t feel it is. The mannequin doesn’t puke on me, it doesn’t swell, it’s hard and inflexible and really greased from all the previous practice. I’ve had 3 attempts since then in he field and my stats are 1:1 and 1. 1 of them no one could get an advanced airway, 1 I missed and 1 was gold. Those incidents do not inspire me to have confidence but when I ask about BLS airways or using the KING I am always told they are not definitive, not the gold standard and I should be more proficient. I read the forums where people cut down medics who had problems with ET tubes but I remember clearly during my internship if I didn’t hit it the first try I was always requested to step back and let them do it. It’s hard to learn from anything when less than 100% perfection is not tolerated in the settings where we are supposed to be learning. 19 intubations is not enough but I was 9 over what was required.

    • medicscribe says:

      Thanks all for your great comments. I think I read somewhere that you need 60 intubations to achieve compentency. It is hard to get those intubations these days. I think I do a pretty good job nowdays — my last three intubations were all after the first medic missed their chances, but having said that, I had my struggles over the years, and the patients didn’t always come out the best for it. Multiple attempts, delays in CPR — it was all about getting the tube in the old days, no alternative airways or focus on the compressions. I am a big believer now in being quick to go to the alternate airway, but this study has be questioning even that.

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