AIRWAY ASSESSMENT TO RULE OUT DIFFICULT INTUBATION.

1. Airway assessment
Dr . Krishnendu S
JR .Department of anesthesia ,
DMIMS

2. Introduction
• Most catastrophes are due to unexpected difficulty or planning in
patients with known difficulty .
• History, examination and investigations must assess the risks of
difficult airway maintenance , ventilation and oxygenation and not
just direct laryngoscope

3. • Congenital airway abnormalities :
Down’s syndrome , Pierre Robin Syndrome, Goldenhar’s syndrome.
• Acquired conditions like rheumatoid arthritis, benign and malignant
tumours of tongue, larynx, etc
• Iatrogenic conditions like oral/ pharyngeal radiotherapy, laryngeal/
tracheal surgery, TMJ surgery
• Reported previous anaesthetic problems

4. GENERAL EXAMINATION
• Adverse anatomical features e.g. small mouth,
receding chin, high arched palate, large tongue,bull neck,
morbid obesity
• Mechanical limitation:
* Reduced mouth opening
* Post-radiotherapy fibrosis
* Poor cervical spine movement
* reduced temporomandibular joint movement
• Poor dentition: prominent/ loose teeth
• Orthopaedic/ orthodontic equipment
• Patency of nasal passage

5. AIRWAY ASSESSMENT
INDICES
• Individual indices
• Group indices:
* Wilson’s score
* Benumof’s analysis
* Saghei & safavi test
* Lemon assessment
• Radiological indices

6. INDIVIDUAL INDICES
Mallampati test
I – faucial pillars , soft
Pallate and uvula visible
II- faial pillars and
soft palate and tip of
uvula
III- only soft palate visible
IV-soft palate not visible .

7. Inter-incisor gap
• Inter-incisor distance with maximal opening
• Normal value >5cm / admits 3fingers.
• Significance:
<3cm : difficult laryngoscopy
<2cm : difficult Laryngeal Mask Airway(LMA) insertion
• Affected by TMJ and upper cervical spine mobility

8. Hyomental distance
• Distance between mentum and hyoid bone
• Grade I: >6cm
• Grade II: 4-6cm
• Grade III: <4cm
• Grade III denotes impossible laryngoscopy &
intubation

9. Sternomental distance(savva test )
• Distance from upper border of the manubrium to the tip of mentum,
neck fully extended mouth closed
• Minimal acceptable value-12.5cm
• Single best predictor of difficult laryngoscopy and intubation

10. Protrusion of mandible :
• Class A : can protrude the lower incisors anterior to the upper incisors
• Class B : can protrude the lower incisors to , but not beyond the
upper incisors
• Class C: cannot protrude the lower incisors to the upper incisors
B&C are associated with increased risk of laryngoscope .

11. • Extension of upper cervical spine :
When limited <90 degree , the risk of laryngoscope is increased

12. GROUP INDICES
1) wilson score

13. 2)Lemon assessment
L- look externally (Facial trauma,Macroglossia,Large incisors , beard or
moustache)
E- evaluate 3-3-2 rule (incisors distance <3fingerbreadth,hyoid-mental
distance<3finger breadth ,thyrohyoid <2 fingers breadth )
M – mallampati score (≥3)
O- obstruction (stridor , tumors , abscesses , inflamed epiglottis or
expanding hematoma)
N-Neck Mobiity (limited neck mobility )
Maximum of 10 points

15. • M- Mallampati score:
Score of 3-4 suggest higher risk

16. Difficult mask ventilation indices
• B-beard and burns
• O-obesity(BMI>26kg/m2)
• N-no teeth-edentulous
• E-Elderly(age >55 years)
• S-Snorer and syndromics
• Facial abnormalities , reciding or protruding jaw , OSA,mallampati class ¾.
• Patients having 2 or > of these predictors are likely to have difficult mask
ventilation.

17. Asssessment of glottic view during laryngoscopy
• 1) indirect mirror laryngoscopic view
• 2)direct laryngoscopic awake look
• Cormack lehane grading
• Grade I-visualization of entire vocal cords
• gradeII-visualization of posterior part of laryngeal aperture
• Grade III-visualization of epiglottis
• Grade IV- no glottic structure seen

18. Difficult airway cart
Special trolley with range of equipments like
Elastic bougie,
Nasopharyngeal airway
LMA
Magill’s forceps
Variety of laryngoscopes with all blades including macoy
Fiberoptic scopes
Tracheal tubes
Cricothyrotomy needles

19. References
• Oxford handbook of anaesthesia 4th edition ,chapter 37,pg 943-997
• Danladi B Mshelia use of the L-E-M-O-N score In predicting difficult
intubation in Africans doi :10.4103/njbcs.njbcs-25-16 .