Airway, Airway, Airway… (part 1)

I didn’t really have to think too long about what my first topical post would be. What is more important to a ditch medicine clinician than the ability to manage a patient’s airway? Answer?…nothing! In the tactical arena things have shifted to a heavy initial focus on life threatening hemorrhage control, and rightfully so. But even in that environment airway management is critical. Point is, regardless of your AO, if you can’t manage a compromised airway in this field, you’re going to have a short career. I’m going to break up airway into a few posts. This is a very complex topic. Be warned these posts might be on the lengthy side. I’m trying to dig into some concepts that are often poorly understood by prehospital providers. My hope is to stimulate some discussion and learning.

I look back on my initial education and training as a baby medic and I shudder. My instructors were great. Top notch. But damn we did not get the advanced airway training we needed. Maybe the thought process at the time was we would perfect those skills in the field. A day or two with the airway mannequin and  a few intubations in surgery (with anesthesiology staff that wanted nothing to do with us) and off we went with laryngoscope in hand. I would like to think that has changed over the years but, sadly, new medics coming out of school seem no better prepared. In addition, experienced personnel aren’t evolving. I see patients coming into the ED without aggressive airway management. Patients who NEED aggressive airway management. Medics are scared to commit. They are afraid of failure. They haven’t been given the confidence in their skills to be aggressive with an airway. It’s a failure of initial training and also of continuing education. Most agencies in my area check off competency once a year. ONCE A YEAR! For a skill that is extremely challenging. And often that skill check is no more than a “wink, wink…you passed” evaluation. Lack of standards. We wonder why as an industry we are failing at prehospital airway management? We have poor standards when it comes to training and competency. Period.

Good news. It’s never too late for any of us to learn. You’re here, reading this, so I assume you care about your skills and knowledge. Read on and see if you learn anything new.

Where to start with airway management? Lets start with reasons to secure a patient’s airway. If you would have asked me that not too long ago I would have stared at you for a minute, then replied, “Because they need it?….They can’t protect their airway?” I imagine if I were to ask many of you I would receive a similar response. Having a strong academic understanding of the reasons you need to secure a patient’s airway is crucial to your success. I now qualify reasons to secure a patient’s airway as the following. (And basically I’m talking about endotrachael intubation but if that’s outside your skill set, these reasons can apply to any intervention at your disposal)

- Failure to ventilate

- Failure to oxygenate

- Failure to protect airway

- Expected clinical course

That’s a short list right? Maybe. But at a macro level, that is a pretty comprehensive set of reasons to take down somebody’s airway. Let’s take a look at those reasons a little more closely.

Failure to ventilate. Ventilation. This is a poorly understood concept in EMS. For quite some time, I operated under the assumption that oxygenation and ventilation were basically the same thing. Ventilation is to cause air to move in and out of the lungs. With ventilation we are, especially, focused on the outgassing of CO2 from the lungs. If a patient cannot manage their CO2, physiological derangement is sure to follow. We utilize measurements like PCO2 and ETCO2 to quantify ventilatory failure. When the CO2 is greater than 55 mm Hg, we technically have ventilatory failure (that # is truly relative to the patient. COPD patient’s, for instance, often live in the 55+ range. So take into context the global health of your patient). What causes failure to ventilate? Pretty much anything that compromises the body’s ability to move air in and out of the lungs or the effective exchange of CO2 at the alveolar/capillary membrane. Some examples: hypoventilation secondary to drug abuse, head injury or CVA involving the respiratory control centers of the brain, COPD, pneumonia and PE all can be causes of ventilatory failure. In order to fix this we have to identify the cause, such as opiate OD, and fix it, in that case with Narcan and hopefully BLS airway/ventilatory managment. In the absence of being able to quickly fix the cause, we have to secure the airway and provide mechanical ventilation to the patient.

Failure to oxygenate. Most of us understand this one pretty well. In fact from day one of medic school we get the concept of oxygenation drilled into our heads non-stop…..overly so (a topic for another post). But as most of you know, oxygenation is the measurement of O2 in our blood available for tissue use. By definition, when the PaO2 drops below 60 mm Hg (approx 90% SPO2), you have a failure to oxygenate. I’m not going hammer too much of the science of hypoxemia. It’s a lack of O2…that’s bad…you get it. Causes? Many of the ventilatory causes also can be causes of poor oxygenation. Anything that prevents O2 from being available in the alveoli for gas exchange. This is called hypoxic hypoxia. Hypoventilation, airway obstruction, reduced partial pressures of O2 when at altitude or diving, mechanical strangulation. In addition, anything that prevents O2 from crossing the alveolar/capillary membrane can cause hypoxemia. Such as pulmonary edema. Pneumonia related lung changes. ARDS is a big one. In ARDS the thickness of that A/c membrane increases to prevent effective gas exchange. How do we fix it? Several options. Increase the amount of oxygen available in the alveoli. That might mean providing supplemental O2. That might mean fixing the ventilatory issues. That might mean providing positive pressure to force the O2 through a fluid or thick membrane to get into circulation. In advanced ventilatory management, we might also have to adjust the ratio of time between inhalation and exhalation to affect oxygenation. Much like failure to ventilate, we must identify the cause and attempt to correct it. Good news is, with oxygenation, in spontaneously breathing patients, usually providing some supp O2 will have immediate positive results.

Failure to protect airway. Out of all the reasons we need to manage a patient’s airway, prehospital providers probably understand this one the best. Doesn’t mean we do it well, but we can sure verbalize it. When I teach airway to a room full of medics, this is the concept the room usually verbalizes frequently. This is a broad etiology but in it’s essence we are taking about patients that because of some derangement in mental status are unable to clear and keep their airway open. The old adage is GCS < 8 )…intubate!  And while that isn’t an entirely accurate mantra for airway management because it fails to consider clinical course, the sentiment it is trying to convey is true. If a patient is obtunded to the point of potential airway collapse, you must intervene. There are so many causes of altered mental status that might qualify a patient for an airway intervention. Hypoperfusion is a big one. Profound drug or alcohol intoxication. Neurological based AMS. The list goes on and on. Some of these causes are more easily resolved than others. Some of these causes won’t be resolved in the prehospital setting, if at all. Whatever the cause, if somebody lacks the capacity to cough, swallow, gag and clear their own airway, that is more than enough reason for you to get aggressive with airway management. Protecting the lungs from potential aspiration of foreign matter is critical. Be aggressive.

Expected clinical course. This is possibly the least understood and least recognized reason to secure a patient’s airway. Expected clinical course is the anticipatory decline in your patient’s condition. A patient in respiratory distress who is becoming lethargic with declining minute volume is a good example of a candidate for aggressive airway management due to expected clinical course. By securing the airway before the patient’s respiratory effort completely fails, we maintain the initiative. We are being proactive instead of reactive. We have more time to prepare. More time to assess the airway and plan for contingencies such as the failed airway algorithm. Another good example is a trauma patient who is becoming hemodynamically unstable. A patient with profound acidosis (pH < 7.2). Airway burns and edema would also fall into this category. Clinical decline in these patient populations is imminent. Intervene before cardiopulmonary collapse is realized. Often airway management for this patient means RSI or conscious sedation for intubation. If you have these procedures at your disposal, be aggressive and proactively secure the airway.

That’s enough for this post. If, like me, you never really had a strong academic understanding of reasons to secure a patient’s airway, I hope this gives you somewhere to start. Please post comments and questions. In part 2 we’ll get into some specific techniques for advanced airway management. Thanks for reading!

1 Comment

  • Tom says:

    Good read, covers a big topic with a broad brush. I particularly appreciate your point on expected clinical course. When I moved from a small, fairly rural service to a much larger, much busier metro service I had a rude awakening to a lot of things that I didn’t know that I didn’t know. Gaining RSI in the new guidelines I was subject to was a daunting prospect. Prior to it, the protocol generally was if they are dead tube ’em…if they aren’t just wait a bit. Having to actually learn when it was appropriate to take a conscious person who had an airway and use RSI was a scary task… but I am glad I have learned and am a better provider for it.

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