Anesthesia airway assessment techniques

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 experienced
in difficult airways

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

17. • ASSESMENT OF A.O.
EXTENSION
• 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 into a straight line.
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

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 5th
digit.
* 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.
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.
SUBLUXATION OFTHE
MANDIBLE

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
(SAVVATEST)
 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 /CATCHTEST
 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. Mallampati Score
 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
Sensitivity: 44% - 81%
Specificity: 60% - 80%
 Roughly corresponds to Cormack and Lehane’s
laryngoscopy views

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

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

41. SAGHEI & SAFAVI’S
 Weight
 Tongue protrusion
 Mouth opening
 Upper incisor length
 Mallampati class
 Head extension
Any 3 indices if present
-
>80kg
< 3.2cm
<5cm
>1.5cm
>1
<70 degree
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. 2005Volume 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. 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.
RADIOGRAPHIC PREDICTORS

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
• Flow volume loop
• Acoustic response measurement
• Ultra sound guided
• CT / MRI
• Flexible bronchoscope
ADVANCED INDICES

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

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

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

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

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

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 spine
Assess all ranges and movement
Silhouette Upper body abnormalities, Identify potential impact on

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 theTMJ function,mouth opening and SM Space. Significant difficulty in 2
or more of these components requires detailed examination.
• 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 1-2-3-4-5
• 3 finger in the interdental space.
• 3 finger between mentum and hyoid bone.
• 3 finger between thyroid cartilage & sternum.
RULE OFTHREE`S

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. 2005Volume 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