Airway Assessment

POSTERIOR COLUMN
The original descriptions of the “sniffing position” emphasised the importance of appropriate
head and neck positioning prior to laryngoscopy 1,2 . The latter work by Greenland and
colleagues reinforced the efficacy of the sniffing position in optimising direct laryngoscopy and
intubating conditions 10 . Achieving the sniffing position is governed by the ability to flex the lower
cervical spine and extend the occipito-atlanto-axial complex. Horton asserted the “ideal angle”
for upper-neck extension and lower-neck flexion to be 15 degrees and 35 degrees, respectively
(Figure 8) 16 . To achieve a true sniffing position in obese patients “ramping” may be required.
The external auditory meatus (as a surrogate marker for the clivus or C1 vertebrae) and the
sternal notch are aligned in the horizontal plane in the ramped position 17-19 .
Figure 8. The sniffing position. The lower neck is flexed to 35 degrees from the torso
and the head is extended to at the antlantooccipital joint, producing a 15 degree angle
between the facial and horizontal plane 8 .
Assessment of the range of movement of the occipito-atlanto-axial complex and the lower
cervical spine forms the basis for evaluation of the Posterior Column 12,13 . The static phase of
direct laryngoscopy is directly coupled to this assessment. Failure to position the patient in
an ideal sniffing position during the static phase will have consequences during the dynamic
phase. Airway operators are at an immediate disadvantage due to the accentuated angulation
of the primary and secondary curves in a neutral position compared to the optimal sniffing
position 10 .
ANTERIOR COLUMN
Evaluation of the anterior column allows the assessor to make inferences regarding the
dynamic phase of laryngoscopy. The anterior column of the neck is bounded by the two
temporo-mandibular joints (TMJ), the mandibular incisors and the hyoid bone – forming an
imaginary inverted triangular pyramid (Figure 9) 12,13 . The base of the pyramid is formed by
the cephalic surface of the tongue and floor of mouth. The contents of anterior complex are
predominantly muscles. The genioglossus anteriorly, and the hyoglossus, styloglossus and
stylopharyngeus posteriorly.
43 Airway Assessment