Airway Class vs. Airway Grade: Know the distinction
Understanding the difference can sometimes make all the difference
Clinicians, like paramedics who intubate patients with poor airway control, will use a few ways to describe the condition of the airway before beginning laryngoscopy, such as a Mallampati Score or Cormack-Lehane Grading. It may be easy to think that one evaluation method is like another, and use them interchangeably. It's better to know that each one provides information about the airway that is distinct from the other.
Airway Class is what you see when looking in the mouth. It’s a means of predicting difficult intubation, and is measured as a Mallampati Score based on how much room there is inside the mouth.
Airway Grade is what you see in the posterior pharynx with a laryngoscope. It is a more accurate measure of how much trouble you are going to have passing a tube, and is evaluated with a Cormack-Lehane Score.
Both are easy to do
Keeping score with ‘class’
Ask the patient to open their mouth wide and protrude their tongue. If you see a lot of room and can visualize the soft palate, uvula, the faucial pillars (the arches over the tonsils), and soft palate that is a Mallampati Class 1.
If you see only see the soft palate, uvula, and faucial pillars, that’s a Class 2. If you only see a little room, usually just the soft palate and base of the uvula, that’s a Class 3. If all you see is the tongue and hard palate that’s a Class 4.
Mallampati is for predicting how much trouble you might have intubating, if the patient is a Mallampati Class 3 or 4, get ready for a challenge.
Getting good ‘grades’
Cormack-Lehane Grading is done with a laryngoscope. It is what you see when performing direct laryngoscopy, and it’s a more accurate way of predicting the actual difficulty of putting a tube in. It’s also used to document how tough the airway really is.
If you see the entire glottis after positioning the laryngoscope, that is a Grade 1 Airway. If you have a partial view, that’s a Grade 2. If you can only see the epiglottis, that’s a Grade 3. If you cannot see the epiglottis, that’s a Grade 4, or very difficult.
Have all your equipment prepared before attempting, including your back up airway devices. You might be well served to go straight to a video-laryngoscope on your first attempt if you have one. Don’t wait for a failure; prepare for it.
In EMS, most patients that we intubate are unconscious and/or non-breathing. That makes it tough to have them open their mouth for us, which often makes it challenging to get a Mallampati Score for Airway Class before attempting intubation.
There is one important exception and that’s when we do rapid sequence intubation (RSI). Medics should always assess Mallampati before pushing the syringe plunger. Take an extra few seconds to know what you are getting into before you jump off the deep end.
Remember, Class and Grade don’t always correlate. They are not interchangeable or different ways of saying the same thing.
A Mallampati Class 1 is not always a Cormack-Lehane Grade 1 airway. Neither is a Mallampati Class 4 always a nearly impossible intubation — it just flags you to consider the possibility early enough to be ready for it.
I hope that clears up any confusion about what these two different scores really mean.