This document discusses preoperative airway assessment. It begins by defining the airway and why assessing it is important, as respiratory events are a leading cause of anesthesia-related injuries. It then defines what constitutes a difficult airway and lists various individual predictors and scoring systems that can be used for assessment, including measurements of neck and mouth structures. Overall, thorough preoperative airway examination involving multiple predictive tests can help identify patients that may present difficulties during ventilation or intubation.

1. Preoperative Airway
Assessment
Dr MANISH KHANDELWAL
SMS MEDICAL COLLEGE
MODERATOR
Dr AMIT KULSHRESTHA

2. Airway
The passage through which the air passes
during respiration
 Nasal and oral cavities
 Pharynx
 Larynx
 Trachea and large bronchi

3. Why it is necessary ??
 Respiratory events are the most common anaesthetic
related injuries, following dental damage. Three main
causes:
◦ Inadequate ventilation
◦ Oesophageal intubation
◦ Difficult tracheal intubation
 Difficult tracheal intubation accounts for 17% of the
respiratory related injuries and results in significant
morbidity and mortality.
 Estimated that up to 28% of all anaesthetic related deaths
are secondary to the inability to mask ventilate or
intubate.
 Prediction of the difficult airway allows time for proper
selection of equipment, technique and personnel

4. Difficult airway
ASA definition of difficult airway:
―The clinical situation in which a
conventionally trained anaesthetist
experiences difficulty with mask
ventilation, difficulty with tracheal
intubation or both.‖

5. Difficult ventilation
The inability of a trained anesthetist to
maintain the oxygen saturation > 90%
using a face mask for ventilation and
100% inspired oxygen, provided that
the pre-ventilation oxygen saturation
level was within the normal range.

6. Difficult intubation
 More than 3 attempts
 Longer than 10 minutes
 Failure of optimal best attempt

7. Prevalence
 Difficult face mask
◦ 0.1% - 5%
 Difficult LMA
◦ 0.2% - 1%
 Difficult intubation
◦ 1-2% of normal surgical population
◦ 50% of rheumatic cervical disease

8. Components of the Airway
Examination
 Nostril patency
 Length of the upper incisors, alignment
 Condition of the teeth
 Relationship of the upper (maxillary) incisors to the
lower (mandibular) incisors
 Ability to protrude or advance the lower (mandibular)
incisors in front of the upper (maxillary) incisors
 Interincisor or intergum (if edentulous) distance
 Tongue size
 Visibility of the uvula e.g. mallampati
 Presence of heavy facial hair
 Compliance of the mandibular space
 Thyromental distance with the head in maximum
extension
 Length of the neck
 Thickness or circumference of the neck
 Range of motion of the head and neck
 Cheek pad

9. Causes of difficult
airway
 Stiffness
◦ Arthritis of neck/jaw/larynx.
◦ Fixation devices
◦ Scleroderma
◦ Diabetes
 Deformity
◦ Cervical and craniofacial
◦ Burns/trauma/infection
 Swelling
◦ Infection/tumour/trauma/burns
◦ Anaphylaxis/haematoma/acromegaly
 Reflexes
◦ Cough/breathholding
◦ Laryngospasm/salivation/regurgitation
 Foreign body
 Other – Pregnant/full stomach

10. Airway assessment
 History
◦ Patient/notes/chart/medic-alert/spam letter
 Difficulty
 Surgery/burns
 Concurrent disease
 Reflux/recent meals
 General examination
◦ Do they just look difficult?
 Dentition (prominent upper incisors, receding chin)
 Distortion (edema, blood, vomits, tumor, infection)
 Disproportion (short chin-to-larynx distance, bull neck, large tongue, small
mouth)
 Dysmobility (TMJ and cervical spine)
◦ Massively obese or pregnant
◦ Beards +/- tubes
 Specific tests/indices
 Investigations.
◦ Nasoendoscopy
◦ X-ray, CT/MRI
◦ Flow volume loop

11. How do you assess ??
The airway may be assessed for difficult airway using
:-
-Individual indices
-Group indices(with and without scoring)
Mask ventilation precedes laryngoscopy, which inturn
followed by, intubation.
So the assessment should be in a systemic manner.

12. Predictors of difficulty to face
mask ventilate (OBESE)
1. The Obese (body mass index > 26 kg/m2)
2. The Bearded
3. The Elderly (older than 55 y)
4. The Snorers
5. The Edentulous
(=BONES)

13. Predictors of difficulty to face
mask ventilate (MOANS)
 MOANS
This is identicle to BONES except ‗M‘.
-Mask seal difficult due to receding
mandible,syndromes with facial abnormalities,burn
stricture etc.
-Obesity, upper airway Obstruction
-Advanced age
-No teeth
-Snorer

14. Predictors of difficult
laryngoscopy and intubation
Individual indices
-Physical examination indices
-radiological indices
-advanced indices
Group indices
- Wilson‘s score
- Benumof‘s analysis
- Saghei & safavi test
- Lemon assesment
- Arne‘s simplified score
- Magboul‘s 4 M‘s

15. Atlanto-occipital movement
 The patient is asked to hold head erect, facing directly to the front,
then he is asked to extend the head maximally and the examiner
estimates the angle traversed by the occlusal surface of upper
teeth.
◦ Visual assessment or using a goniometer.
 Grade I >35 degrees
 Grade II 22-34 degrees
 Grade III 12–21 degrees
 Grade IV <12 degrees
 Assesses feasibility to make the optimal intubation position with
alignment of oral, pharyngeal and laryngeal axes into a straight
line.
 Limited A-O joint extension
◦ Spondylosis, rheumatoid arthritis, halo-jacket fixation, and in patients
with symptoms indicating nerve compression with cervical extension.

16. Grading of reduction in A.O.Extension
Grade I : > 35°
Grade II : 22-34°
Grade III : 12-21°
Grade IV: < 12°
Grade Reduction of A.O.Extension
1 none
2 One third
3 Two third
4 complete
Grades 3 and 4 : Difficult laryngoscopy

17. • ASSESMENT OF A.O. EXTENSION
can also be done by asking the patient to look at
the floor and at wall after fully flexing and fixing the
neck as shown
• Flexion movement of the cervical spine can be
assessed by asking the patient to touch his manubrium
sternii with his chin. If done, the above maneuver
assures a neck flexion of 25- 35 degree. Flexion and the
extension movement if within the normal range ,three
axis ( oral,pharyngeal & laryngeal axis) can be brought

18. Warning sign of DELIKAN
Place the index finger of each hand, one underneath
the chin and one under the inferior occipital
prominence with the head in neutral position. The
patient is asked to fully extend the head on neck. If
the finger under the chin is seen to be higher than the
other, there would appear to be no difficulty with
intubation. If level of both fingers remains same or the
chin finger remains lower than the
-: other, increased difficulty is predicted.

19. PRAYER SIGN
A positive "prayer sign" can be
elicited on examination with the
patient unable to approximate
the palmar surfaces of the
phalangeal joints while pressing
their hands together.
Seen in diabeties
; This represents:- cervical spine
immobility and the potential for
a difficult endotracheal
intubation.

20. Palm Print test
The palm and fingers of the dominant hand of the
patient is painted with black writing ink using a brush.
The patient then presses the hand firmly against a white
sheet of paper on a hard surface. Scoring is done as:
* Grade 0 - All phalangeal areas visible.
* Grade 1 - Deficiency in the inter-phalangeal areas of
4th and/or 5thdigit.
* Grade2 - Deficiency in the inter-phalangeal areas of
2nd to 5th digit.
* Grade 3 - Only the tips of digits seen.

21. Palm Print as a Predictor of
Difficult Airway in DM

22. ASSESSMENT OF TMJ FUNCTION
TM joint exhibits 2 function.
1. Rotation of the condyle in the s.cavity.
2. Forward displacement of the condyle.
First movement is responsible for 2-3cm mouth opening
& the second is responsible for further 2-3cm mouth
opening.
SUBLUXATION OF THE MANDIBLE
Index finger is placed in front of the tragus & the thumb is
placed in front of the the lower part of the mastoid process.
patient is asked to open his mouth as wide as possible. Index
finger in front of the tragus can be intented in its space and
the thumb can feel the sliding movement of the condyle as
the condyle of the mandible slides forward.

23. Significance-
Class B and C: difficult laryngoscopy

24. Assessment of mandibular
space
 can be expressed as thyromental and
hyomental space.
 This space determines how easily the
laryngeal and pharyngeal axis will fall
in line when the a-o joint is extended.

25. Thyromental Distance
Measure from upper edge of thyroid
cartilage to chin with the head fully
extended. Normal is approx 7cm.
If the thyromental distance is short, <3
finger widths, the laryngeal axis makes
a more acute angle with the pharyngeal
axis and it will be difficult to achieve
alignment.Less space to displace the
tongue

26. Limitations
 Little reliability in prediction
 Variation according to height, ethnicity
Modification to improve the accuracy
 Ratio of height to thyromental distance (RHTMD)
 Useful bedside screening test
 RHTMD > 23.5 – very sensitive predictor of difficult
laryngoscopy
Thyromental Distance
PATIL’S TEST

27. HYO MENTAL DISTANCE
 Distance between mentum
and hyoid bone
 Grade I : > 6cm
 Grade II: 4 – 6cm
 Grade III : < 4cm –
Impossible laryngoscopy &
Intubation

28. INTER-INCISOR GAP
 Inter-incisor distance with maximal mouth opening
 Normal value > 5 cm / admits 3 fingers.
Significance :
 Positive results: Easy insertion of a 3 cm deep
flange of the laryngoscope blade
 < 3 cm: difficult laryngoscopy
 < 2 cm: difficult LMA insertion
 Affected by TMJ and upper cervical spine mobility

29. STERNOMENTAL DISTANCE (SAVVA
TEST)
 Distance from the upper border of the manubrium
to the tip of mentum, neck fully extended, mouth
closed
 Minimal acceptable value – 12.5 cm
 Single best predictor of difficult laryngoscopy and
intubation ( Has high sensitivity & specificity).

30. UPPER LIP BITE /CATCH TEST
 Class I: Lower incisors can bite the upper lip above
vermilion line
 Class II: can bite the upper lip below vermilion line
 Class III: cannot bite the upper lip
Significance
 Assessment of mandibular movement and dental
architecture
 Less inter observer variability

31. Test for assessing adequacy of
the oropharynx for laryngoscopy
and intubation
 Mallampati grading (samsoon and young‘s
modification)
 Narrowness of the palate

32. Sensitivity: 44% - 81%
Mallampati Score Specificity: 60% - 80%
 Roughly corresponds to Cormack and Lehane‘s
laryngoscopy views
 Class I (easy)—visualization of the soft palate,
fauces, uvula, and both anterior and posterior
pillars
 Class II—visualization of the soft palate, fauces,
and uvula
 Class III—visualization of the soft palate and the
base of the uvula
 Class IV (difficult)—the soft palate is not visible at all

34. SIGNIFICANCE OF MMP SCORE
 Class III or IV: signifies that the angle between
the base of tongue and laryngeal inlet is more
acute and not conducive for easy laryngoscopy
 Limitations
◦ Poor interobserver reliability
◦ Limited accuracy
 Good predictor in pregnancy, obesity, acromegaly

35. Assessment for quality of glottic
viewing during laryngoscopy
Indirect mirror laryngoscopic view
Direct laryngoscopy ‗awake look‘
-cormack and lehane grading
Grading ease of intubation
POGO (percentage of glottic opening)
scoring

36. CORMACK - LEHANE
Grading at direct laryngoscopy
 Grade 1: Full exposure of glottis (anterior + posterior
commissure)
Grade 2: Anterior commissure not visualised
Grade3: Epiglottis only
Grade 4: No glottic structure visible.
Grade I = success & ease of intubation

38. Group indices
- Wilson‘s score
- Benumof‘s analysis
- Saghei & safavi test
- Lemon assesment
- Arne‘s simplified score
- Magboul‘s 4 M‘s
- 4D‘s

39. Wilson‘s risk score
Score • Head movement assessed
Weight 0=<90kg
with pencil taped to a
1=>90kg patient’s forehead.
2=>110kg
•IG = Interincisor gap
Head and 0=Above 90degrees
neck 1=About 90degrees
measured with mouth fully
movement 2=Below 90degrees open.
Jaw 0=IG>5cm or SLux >0 •SLux = Maximal forward
movement 1=IG<5cm and SLux = 0
2=IG<5cm and SLux<0
protrusion of the lower
incisors beyond the upper
Receding 0=Normal
mandible 1=Moderate
incisors.
2=Severe •score 5 or < =easy laryngoscopy
Buck teeth 0=Normal
•Score 8-10 =severe difficulty in
1=Moderate
laryngoscopy
2=Severe

40. BENUMOF’S 11 PARAMETER ANALYSIS
Parameter Minimum acceptable
value
1. Buck teeth <1.5cm
2. Subluxation Absent
3. Interincisor gap Yes
4. Palate configuration >3cm
5. Mallampati class No arching/narrowness 4-2-2-3 rule
6. Upper inciors length <2 4 for tooth
7. TM distance > 5cm 2 for inside of mouth
8. SMS compliance Soft to palpation. 2 for mandibular space
9. Neck thickness Qualitative ( >33cm DI) 3 for neck examination.
10. Length of neck >8cm
11. Head /neck mvt Normal range

41. SAGHEI & SAFAVI’S
 Weight >80kg
 Tongue protrusion < 3.2cm
 Mouth opening <5cm
 Upper incisor length >1.5cm
 Mallampati class >1
 Head extension <70 degree
Any 3 indices if present Prolonged laryngoscopy
-

42. Arne’s simplified score model
 The points of simplified score were obtained by multiplying the points of the
exact score by 3.15 and then rounding the results to the nearest whole number.
 Risk factor simplified score
 Previous knowledge of difficult intubation
No 0
Yes 10
 Pathologies associated with difficult intubation
No 0
Yes 5
 Clinical symptoms of airway pathology
No 0
Yes 3
 Inter-incisor gap (IG) and mandible luxatum (ML)
IG > 5 cm or ML >0 0
IG 3.5-5cm and ML=0 3
IG<3.5 cm and ML<0 13

43. Arne’s simplified score contd.
 Thyromental distance simplified score
>6.5cm 0
< 6.5cm 4
 Maximum range of head & neck movement
Above 100° 0
About 90° (90° ± 10°) 2
Below 80° 5
 Mallampati’s modified test
Class 1 0
Class 2 2
Class 3 6
Class 4 8
Total...... 48
Score of >11 is predictive of difficult tracheal intubation
Indian journal of anaesthesia,2002; 46(5) 347-352

44. LEMON trial
 Look
 Facial trauma
 Large incisors
 Beard
 Large tongue
 Evaluate 3-3-2
 Interincisor distance (3 fingers)
 Hyoidmental distance (3 fingers)
 Thyroid to floor of mouth (2fingers)
 Mallampati
 Obstruction
 Neck movement – chin to chest
( Airway management in trauma
Indian J Anaesth. 2011 Sep-Oct; 55(5): 46)3–469)

45. LOOK Externally
 Beards or facial hair
 Short, fat neck
 Morbidly obese patients
 Facial or neck trauma
 Broken teeth (can lacerate balloons)
 Dentures (should be removed)
 Large teeth
 Protruding tongue
 A narrow or abnormally shaped face

46. EVALUATE 3-3-2
 Mouth Opens at least 3 finger widths.
 Three finger widths thyromental
distance.
 Two finger widths mandibulohyoid
distance.

47. Mouth opens at least 3 fingers
width?

48. Upper & Lower Face
 Measure the size of the upper face as compared
to the lower face.
 Should be roughly the same.
 If the lower face is longer than the upper face then
you should anticipate some degree of difficulty
lining up the structures

49. Upper and lower face equal?

50. Upper and lower face equal?

51. Obstruction
 Laryngoscopy or intubation may be more
difficult in the presence of an obstruction
◦ Anatomy
◦ Trauma
◦ Foreign body obstruction
◦ Edema (burns)

52. Neck Mobility
 Ideally the neck should be able to
extend back approximately 35
 Problems:
◦ Cervical Spine Immobilization
◦ Ankylosing Spondylitis
◦ Rheumatoid Arthritis
◦ Halo fixation

53. Scene and Situation (SEE)
 Scene safety
 Environment
◦ Do you have a reasonable chance to get
the tube?
◦ Space, positioning, access
 Egress
◦ Will you be able to ventilate during
egress?

54. Magboul‘s 4 M‘s
 For Intubation remember the 4(M & Ms) with (STOP) sign
 Mallampati
 Measurement
 Movement
 Malformation & STOP
 M =Malformation of the skull, teeth, obstruction, & Pathology (the
Macros and Micros). We can memorize them with the word (STOP)
 S = Skull (Hydro and Microcephalus)
 T = Teeth (Buck, protruded, & loose teeth. Macro and Micro
mandibles)
 O= Obstruction (due to obesity, short Bull Neck and swellings
around the head and neck)
 P = Pathology (Craniofacial abnormalities & Syndromes: Treacher
Collins, Goldenhar's, Pierre Robin, Waardenburg syndromes) .
 (The Internet Journal of Anesthesiology. 2005 Volume 10 Number 1.
DOI: 10.5580/1d0a)

55. What are the 4 Ds?
The following Four D's also suggest a difficult airway:
 Dentition (prominent upper incisors, receding chin)
 Distortion (edema, blood, vomits, tumor, infection)
 Disproportion (short chin-to-larynx distance, bull
neck, large tongue, small mouth)
 Dysmobility (TMJ and cervical spine)

56. RADIOGRAPHIC
PREDICTORS
1. X-Ray neck (lateral view) :
 Occiput - C1 spinous process
distance< 5mm.
 Increase in posterior mandible
depth > 2.5cm.
 Ratio of effective mandibular
length to its posterior depth
<3.6.
 Tracheal compression.

57. 2. CT Scan:
 Tumors of floor of mouth, pharynx, larynx
 Cervical spine trauma, inflammation
 Mediastinal mass
3. Helical CT (3D-reconstruction):
 Exact location and degree of airway compression
ADVANCED INDICES
• Flow volume loop
• Acoustic response measurement
• Ultra sound guided
• CT / MRI
• Flexible bronchoscope

58. DOA
Difficult Airway
 DOA
◦ Disruption or Distortion
◦ Obstruction
◦ Access Problems

59. DOA
Disruption / Distortion
 Distortion
◦ Surgeries
◦ Radiation Therapy
◦ Scarring
◦ Burns

60. DOA
Disruption / Distortion
 Disruption
◦ Hanging
◦ Crush Injuries
◦ Penetrating Trauma
◦ Other Soft Tissue Trauma
 Burns
 Laceration

61. DOA
Obstructions
 Hematoma
 Abscess
 Tumor
◦ Tumors can also create distortions & extra
bleeding

62. DOA
Access Issues
 Obesity
 Halo
 Short neck
 SC Emphysema
 Bushy beard
 Flexion deformity of the spine

63. How to predict difficult placement
of supraglottic devices (RODS)
 Restricted mouth opening
 Obstruction of the upper airway
 Distrupted upper airway as following
trauma,burn,caustic ingestion .
 Stiff lung (poor lung or thoracic
compliance)
Suggested by Hung and Murphy
(Canadian journal of anesthesia 2004:10:963-8)

64. How to predict difficulty in
creating surgical airway (BANG)
 Bleeding tendency
 Agitated patient
 Neck scarring
 Growth or vascular abnormality in
region of surgical airway.

65. Why would this man’s airway
be difficult to manage?

73. COPUR index assessing difficult airway in
paediatric patient
 C-chin From the side view the chin is: score
Normal 1
Small, moderately hypoplastic 2
Markedly recessive 3
Extremely hypoplastic 4
 O-Opening of the mouth(Interdental space)
> 40mm 1
20-40 mm 2
10-20mm 3
<10 4
 P-Previous Intubation or OSA
Previous attempt easy 1
No previous attempt, no hx OSA 2
OSA, previous hx difficult intubation 3
Extremely difficult previous intubation, trach,
or patient unable to lie supine 4

74. COPUR index (contd)
 U-Uvula (Mouth open tongue out)
Tip of uvula visible 1
Uvula partially visible 2
Uvula concealed, soft palate visible 3
Soft palate not visible 4
 R Range (estimaterange of motion looking up and down)
>120° 1
60°-120° 2
30°-60° 3
< 30° 4
 Prediction Points
 5-7 Easy normal intubation score >10 predict difficult airway
 8-10 laryngeal pressure may help
 12 more difficult, fiberoptic may be less traumatic
 14 Difficult intubation, fiberoptic or other advanced technique
 16 Dangerous airway, consider awake intubation, potential trach

75. Structured Approach to Airway
Management
 MOUTHS
Component Description Assessment Activities
Mandible Length and subluxation Measure hyomental distance and
anterior displacement of mandible
Opening Base, symmetry, range Assess and measure mouth opening
in centimetres
Uvula Visibility Assess pharyngeal structures and
classify
Teeth Dentition Assess for presence of loose teeth
and dental appliances
Head Flexion, extension, rotation
of head/neck and cervical
Assess all ranges and movement
spine
Silhouette Upper body abnormalities,
both anterior and posterior
Identify potential impact on control
of airway of large breasts, buffalo
hump, kyphosis, etc.

76. Rule of 1-2-3
 1 finger breadth for subluxation of mandible. Just to
recall
 2 finger breatdh for adequacy of mouth opening.
 3 finger breathd for hyomental distance.
In emergency situation, above test can be rapidly performed within 15sec
to assess the TMJ function,mouth opening and SM Space. Significant
difficulty in 2 or more of these components requires detailed
examination.
Rule of 1-2-3-4-5
• 4 finger breath for thyromental distance
• 5 movements- ability to flex the neck upto the manubrium sterni,
extension at the AOJ, rotation of the head along with right & left
movement of the head to touch the shoulder.
RULE OF THREE`S
• 3 finger in the interdental space.
• 3 finger between mentum and hyoid bone.
• 3 finger between thyroid cartilage & sternum.

77. To Summarize
 Airway assessment is a critical part .
 The difficult airway assessment must be
performed prior to ALL attempts.
 While this criteria helps identify difficult
airways, it does not guarantee an easy
intubation—Be Prepared!
 Nothing is more expensive than
the missed opportunity

78. References
 Airway management in trauma
Indian J Anaesth. 2011 Sep-Oct; 55(5): 463–469.
 The Internet Journal of Anesthesiology ISSN: 1092-406X
The Dilemma of Airway Assessment and Evaluation
Magboul M. Ali Magboul MD, FFARCSIClinical Assistant Professor,
Director of ACLS, PALS & Airway workshop, Department of Anesthesia,
University of IowaIowa City, Iowa U.S.A.
Citation: M.M. Ali Magboul: The Dilemma of Airway Assessment and
Evaluation.The Internet Journal of Anesthesiology. 2005 Volume 10 Number
1. DOI: 10.5580/1d0a
 Practice guidelines for management of the difficult airway: an updated report
by the American Society of Anesthesiologists Task Force on Management of
the Difficult Airway. Anesthesiology 2003; 98 (5):1269-77
 Frerk CM. Predicting difficult intubation. Anaesthesia 1991; 46 (12):1005-8
 Verghese C, Brimacombe JR. Survey of laryngeal mask airway usage in
11,910 patients: safety and efficacy for conventional and nonconventional
usage. Anesth Analg 1996; 82: 129–33
 Gupta S, Sharma R, Jain D. Airway assessment – Predictors of a Difficult
Airway. Indian Journal Of Anaesthetics 2005; 49(4) : 257 -262