6.1 Airway Assessment
Key Takeaways
- LEMON predicts difficult laryngoscopy, MOANS predicts difficult bag-mask ventilation, and RODS predicts difficult supraglottic placement—score all three before you commit.
- Mallampati III–IV, thyromental distance under three fingerbreadths, and a failed 3-3-2 rule mark a predicted difficult view before anyone opens a blade.
- Beard, obesity, pregnancy, burns, angioedema, blood, vomitus, and a C-collar change the question from "can I see cords" to "can I bag, seat a supraglottic, or cut."
- Waveform end-tidal carbon dioxide is the real-time airway monitor; colorimetric paper and pulse oximetry lag or fail in a cold, soiled, vibrating cabin.
- A closing airway is managed on the ground; a hypotensive open airway is resuscitated first—do not discover a Mallampati IV after lift.
Airway assessment in flight is a prediction problem, not a last-second glance at the teeth. Domain 2 of the August 2026 Board of Certification for Emergency Nursing (BCEN) Certified Flight Registered Nurse (CFRN) outline tests airway assessment before it tests the tube. You decide whether bag-valve-mask (BVM) ventilation, laryngoscopy, a supraglottic airway (SGA), or a surgical airway will fail—then you decide whether to manage now or resuscitate first. The cabin will not give you a quiet second look.
Three mnemonics, three different failures
Score all three out loud on the ramp. A patient can be easy to bag and impossible to intubate, or the reverse.
LEMON: difficult laryngoscopy
LEMON predicts a hard direct laryngoscopy (DL) or video laryngoscopy (VL) view: Look externally (trauma, burns, small mandible, large tongue, short neck); Evaluate the 3-3-2 rule (three fingerbreadths of mouth opening, three of thyromental distance (TMD), two between thyroid notch and hyoid); Mallampati class; Obstruction or obesity; Neck mobility, including a rigid cervical (C-)spine collar. A failed 3-3-2 or Mallampati III–IV forbids casual intubation with one blade and no backup.
MOANS: difficult bag-mask ventilation
MOANS predicts that a single-handed BVM will leak or will not move the chest: Mask seal (beard, blood, facial fractures, burned lips); Obesity or obstruction; Aged patients with lost tissue tone; No teeth, so the face collapses under the cushion; Stiff lungs or chest—status asthmaticus, chronic obstructive pulmonary disease (COPD), late pregnancy, circumferential torso burns. If MOANS is dirty, plan two-person BVM and an early SGA before anyone opens a drug box.
RODS: difficult SGA placement
RODS predicts that an i-gel, laryngeal mask airway (LMA), or King LT will not seat or ventilate: Restricted mouth opening; Obstruction; Distorted anatomy (angioedema, hematoma, burned airway); Stiff lungs or C-spine limitation. Failing all three also predicts a difficult surgical airway—palpate the cricothyroid membrane now. Short neck, obesity, and hematoma hide the landmarks.
Measurements and scene findings
Mallampati, 3-3-2, and neck mobility
Mallampati is ideally scored sitting, mouth open, tongue out, no phonation. On a backboard, score what you can.
| Class | What you see | Flight implication |
|---|---|---|
| I | Soft palate, uvula, fauces, and pillars | Reassuring if the rest of LEMON is clean |
| II | Soft palate, uvula, and fauces | Usually workable |
| III | Soft palate and base of the uvula only | Predicted difficult laryngoscopy |
| IV | Hard palate only | High-risk view; stage VL, a bougie, and an open surgical kit |
Thyromental distance under three adult fingerbreadths (about 6 cm) means little room to align axes. Combine mouth opening, TMD, and hyoid-to-thyroid distance as the 3-3-2 rule. Neck mobility is often already gone: open a rigid collar with manual in-line stabilization for the look, then close it.
Beard, obesity, and pregnancy wreck mask seal and functional residual capacity (FRC) together. A third-trimester patient desaturates in seconds—ramp her and expect a difficult BVM. Burns and inhalation injury add soot, singed hair, carbonaceous sputum, and hoarseness; voice change or stridor is a reason to manage early, not to watch it at altitude. Angioedema—allergic, angiotensin-converting enzyme (ACE) inhibitor, or hereditary—can fill the floor of the mouth; plan a surgical airway before you burn your only look. Trauma brings blood, vomitus, loose teeth, and the C-collar. A soiled pharynx is a predicted difficult VL and a predicted difficult BVM—have two suctions in your hands before you commit.
Monitoring, timing, and children
Waveform end-tidal carbon dioxide (ETCO2) is the continuous airway monitor. A four-phase capnograph means exhaled carbon dioxide is moving through the device. A colorimetric detector can help as a first glance, but gastric contents, epinephrine, and a cold wet cabin stain or wash out the paper. Color without a waveform is not your standard. Pulse oximetry lags 15–45 seconds after apnea, then falls off a cliff; a cold vibrating probe also lies by artifact.
Resuscitate before you intubate is the decision rule section 6.2 operationalizes. If the patient is hypotensive or still fighting the mask, the next action is often blood, a vasopressor, and oxygen—not a blade. Exceptions are the closing airway: anaphylaxis, angioedema, inhalation injury with voice change, or a soiled trauma airway you cannot keep open. Manage those on the ground if the aircraft has not lifted.
Children are not small adults. The occiput is large, so a towel under the shoulders—not an adult ramp—opens the airway. The tongue is relatively large, the larynx is more cephalad and anterior, and in the young child the narrowest fixed point is the cricoid ring. The trachea is short, so a mainstem is one centimeter away. Full pediatric pharmacology belongs in Chapter 18.
- Score LEMON, MOANS, and RODS out loud before anyone induces.
- Treat Mallampati III–IV, a short TMD, and a failed 3-3-2 as a predicted difficult view.
- Plan two-person BVM early when beard, blood, obesity, or pregnancy wrecks the seal.
- Trust waveform ETCO2; treat pulse oximetry and colorimetric change as delayed or dirty signals.
- If the airway is not closing, optimize first. If it is closing, manage on the ramp.
A flight nurse is packaging a bearded, edentulous, obese patient with a rigid cervical collar. Which mnemonic best predicts that single-handed bag-mask ventilation will fail?
After a scene intubation on the ramp, which finding is the most reliable confirmation of tracheal placement before lift?
A hypotensive burn patient has soot in the airway and a hoarse voice. Blood pressure is 78/50 mm Hg. What is the best next airway decision?