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’
If you ask the patient to open their mouth wide and you see a lot of room and large dark space, that is a Mallampati Class 1. If you see some room but not a lot, that’s a Class 2. If you see just a little room, that’s a Class 3. If you don’t see anything but tongue, that’s a Class 4.
Since Mallampati is for predicting how much trouble you might have intubating, if the patient is a Mallampati Class 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.