Week #6 as a CRNA Student- Airway, airway, airway!

by admin

Remember when you were in nursing school and you learned how to put in IV’s? Remember when you found yourself staring at strangers’ veins in the grocery store and when you bugged family members to let them allow you to look at their veins? Well now I’m doing the same thing, but with airways.

Why would anyone pierce their uvula??

Here are some tools you can use to determine whether a patient has a greater chance of having a difficult airway.  Each one by itself is not a proven predictor of a difficult airway, but when used in combination can help you make an educated guess.  From what we have learned, however, there are still going to be cases where you think a patient will be an “easy” airway and turns out to be difficult (and vice versa).  That’s why we also have a plan B, C and D.

Airway Assessment

Mallampati (MP) Scores

Have the patient sit up-right, tilt the chin back, open the mouth wide and stick out their tongue.  There is some controversy on whether the patient should say “ahhhhh” while they’re sticking out their tongue.  We learned that the patient should NOT phonate because it can cause elevation of the soft palate.  But then again, some studies say the exam is improved with phonation.  Basically, the MP Score is assessing the size of the tongue related to the oral cavity and is based on whether the viewer can see the following 4 structures: faucial pillars, hard palate, soft palate, and uvula.

Mallampati Classes I to IV

MP Class I- Soft palate, tonsillar fauces, tonsillar pillars, and uvula

MP Class II- Soft palate, tonsillar fauces, partial uvula

MP Class III- Soft palate, base of uvula

MP Class IV- Hard palate only

MP III and MP IV are associated with greater likelihood of a difficult airway.

Thyromental Distance

Have the patient extend their head fully.  Measure from the mentum (chin) to the thyroid notch.  Over 7 cm (around 3 fingerbreadths) is associated with easier intubation.  Less than 6cm may mean a difficult airway because you would assume the patient has an anterior larynx and less space for the tongue to be compressed out of the way by the laryngoscopy blade.

Mouth Opening/Inter-Incisor Distance

You normally have to put a blade into a patient’s mouth so you need to know how far they can open their mouth, and the distance from the top incisors to the bottom incisors (because again- you have to put a blade in their mouth).  Mouth opening can be limited by TMJ disorders and any sort of jaw trauma.

Jaw Mobility

Like I touched on above, mouth opening can be affected by jaw mobility.  Have the patient touch their upper lip with their bottom teeth (e.g. make an underbite).  If they can do this, their jaw mobility is not likely to be an issue.


Buck teeth and large incisors can interfere with blade placement.  Loose teeth, loose crowns, cracked teeth, and chipped teeth must be documented beforehand.  The anesthesia provider should discuss the risks of damage to the teeth from the laryngoscopy blade.  Patients that take meth, bulimic patients, and patients with reflux are likely to have tooth erosion and may be at higher risk for damage.  Ask if your patient has dentures, partials, or any other type of dental appliance that can be removed.

Cervical Mobility

Ask the patient to turn her head from side to side, and up and down.  Some patients cannot be placed in the “sniffing position” secondary to neck trauma, cervical collar, musculoskeletal disorders like kyphosis and rheumatoid arthritis.  This prevents the provider from being able to place the patients head in the appropriate alignment that would allow for the best visualization of the airway.

Neck Circumference & Body Mass Index (BMI)

A neck circumference of greater than 45cm in an obese patient with a BMI of greater than 40kg/m^2 is likely to be a difficult intubation.  Also, women with large pendulous breasts add a degree of difficulty to an intubation because the provider may not be able to position the blade handle appropriately toward the chest.

Prayer Sign

Ask patient to place palms flat together like they are praying.  Patients that cannot place palms flat are likely to have decreased joint and cartilage mobility in their neck as well.  This could mean difficult intubation.

Facial Hair

Facial hair can make mask ventilation difficult because it is hard to get a good seal.  Also, facial hair can mask other signs of a difficult airway- like short thyromental distance.  This is why you need to physically touch your patient’s neck when determining thyromental distance.

 LEMON Trick

Some providers use the LEMON pneumonic to help them assess an airway

L- Look externally (facial trauma, teeth, facial hair, etc.)

E- Evaluate thyromental distance

M- Mallampati Class

O- Obstruction (airway edema, tracheal mass, mediastinal mass, etc.)

N- Neck mobility

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