This document discusses the identification and management of difficult airways. It notes that maintenance of the airway is the anesthetist's primary responsibility, and 30% of anesthesia-related deaths are due to inability to manage the difficult airway. Key points include: - Properly identifying patients at risk of a difficult airway through history, physical exam, and airway assessments is critical for optimal patient preparation and equipment selection. - Various physical exam tests and indices like Mallampati score, thyromental distance, and neck mobility can help predict difficult intubation. - Multiple techniques and personnel experienced in difficult airway management may be needed to secure the airway when difficulties are encountered. Proper planning can help reduce

1. BY
DR SALONI SOOD
MODERATOR :-DR SHELLY RANA

2. Maintenance of airway is the fundamental
responsibility of the anesthetist.
30% of anesthesia related deaths attributable
to inability to manage DA.
Failed Tracheal intubation once in every 2230
attempts
Failed ventilation accounts for 44% of intra
operative cardiac arrests
THEREFORE IDENTIFICATION OF DA IS HOLY
GRAIL OF CLINICAL MX

3.  Diagnose the potential for difficult airway for
optimal patient preparation
 Proper equipment and technique selection
 Participation of personnel experienced in the
difficult airway management.

4. Difficult Airway :
Clinical scenario in
which conventionally
trained
anesthesiologist
experiences difficulty
with
 Face mask ventilation
 Tracheal intubation
 Both

5. It is not possible for the unassisted
anesthesiologist to maintain oxygen
saturation more than 90% using 100%
oxygen and positive pressure mask
ventilation in a patient whose oxygen
saturation was more than 90%before
anesthetic intervention
And/ or it is not possible for the unassisted
anesthesiologist to prevent or reverse signs
of inadequate ventilation during positive
pressure mask ventilation

6. 2 MAIN REASONS ARE
INADEQUATE SEAL
INADEQUATE PATENCY OF AIRWAY
INCIDENCE:- 0.08 -5%

7. Difficult Laryngoscopy
Not possible to visualize any portion of the vocal
cords after multiple attempts at conventional
laryngoscopy

8. More than 3 attempts
Longer than 10 minutes
Failure of optimal best attempt
Tracheal intubation requiring multiple attempts
in presence or absence of tracheal pathology.
FAILED INTUBATION
Failure of passage of endotracheal tube after
multiple intubation attempts.

10. Adverse outcomes associated with the difficult
airway
◦ Death
◦ Brain injury
◦ Cardio pulmonary arrest
◦ Unnecessary tracheostomy
◦ Airway trauma
◦ Damage to teeth

11. Painless – JUST SCREENING!!
Quick and simple to apply
Essentially bedside
Less inter examiner variation
Reproducible
High sensitivity and positive predictive value

12. HISTORY
PHYSICAL EXAMINATION:
:--GENERAL PHYSICAL EXAMINATION
:--SPECIFIC ASSESSMENT TOOLS
PHYSICAL RADIOLOGICAL
EXAMINATION
ADVANCED IND

13. Detect medical, surgical, and anesthetic
factors
◦ That indicate the presence of a difficult
airway
Previous anesthetic records
◦ History of difficult airway : single most reliable
predictor of a difficult airway

14. Previous anesthetic exposure
Snoring/ history s/o OSA
Trauma to airway/ neck
Burns (airway?)
Neck swelling
Hoarseness
Stridor
Previous neck surgery
Radiotherapy
Systemic diseases : DM/RA
History of piercing???

16. Tounge
Palate :
 High arched
 Long &narrow
Elderly/ cachexic :
buccal pad of fat
Any burns/ wound
Dressings
Epidermolysis bullosa
Skin grafts
Nares :
patency/polyps/DNS
Mouth opening : >3FB
Jaw-
deformity/massive/mus
culatue
Teeth
 Prominent upper
incisors/canines
 Edentulous
 “Buck” teeth

17.  Hair bun : decreased extension of AO Joint
prevents sniffing position
 Beard : difficulty in mask seal
 Facial deformities
 Neck : Short, thick neck  difficult intubation
(17 in-M ; 16in –F)
 BMI : > 30 kg/m2
 Infections of airway
 URI
 Epiglottitis
 Abscess
 Croup
 Bronchitis
 Pneumonia
 Physiologic conditions : Pregnancy

18. 1. The Obese (body mass index > 30 kg/m2)
2. The Bearded
3. The Elderly (older than 55 y)
4. The Snorers
5. The Edentulous
Patients with two or more of there risk factors are
likely to have difficult mask ventilation

19. Mask seal difficult(receding mandible,facial
abn,burn strictures)
Obesity or upper airway Obstruction
Advanced age
No teeth
Snorer

20. Physical Examination Indices
Radiological Indices
Advanced Indices

21. Functions :
Rotation of condyle in synovial cavity (initial
2-3cm of mouth opening)
Forward displacement of the condyle
:(further 2-3cm mouth opening)
Tests for TMJ function
1. Inter incisor gap (IG)
2. Mandible luxation (ML)
3. Mandibular protusion test
4. Upper lip bite test

22. INTER-INCISOR GAP :
Ask patient to open mouth
Place his 3 fingers (index, middle & ring)
Indicates IG >5cm Adequate for direct
laryngoscopy
MANDIBULAR LUXATION :
Index finger in front of tragus
Thumb in front of the lower part of the
mastoid process
Ask patient to open mouth
 Index finger enters in space of condyle
 Thumb feels the sliding of the condyle

28. UPPER LIP BITE TEST : (KHAN ET AL)
◦ Range and freedom of mandibular
movement & architecture of teeth
◦ Class I:
Lower incisors can bite upper lip above vermilion
line
◦ Class II:
Lower incisors can bite upper lip below vermilion
line
◦ Class III:
Lower incisors cannot bite the upper lip
Class III upper lip bite test may have
C&L grade III-IV

30. MALLAMPATI GRADING (1983)
Size of tongue wrt oral cavity
How much of the pharynx is obscured by
tongue
 Patient in sitting pst,observer’ eye at level wid
pt’s mth
 Maximal mouth opening in neutral position
 Maximal tongue protrusion without arching
 No phonation

31. ClassI
Faucial
pillars
Uvula
Soft palate
Hard palate
Class II
Uvula
Soft
palate
Hard
palate
Class III
Uvula
Base
Soft
palate
Hard
palate
Class IV
Hard
palate
Samsoon and Young’s modification of the Mallampati
classification, a IV class was added

32. Failure to consider
 Neck mobility
 Size of the mandibular space
 Inter-observer variability in
classification.
◦ Testing in supine position, phonation
and patient’s arching of tongue cause
inter-observer variability

33. Determines ease of alignment of
laryngeal and pharyngeal axes when the
atlanto-occipital joint is extended
It’s the space ant to larynx.
Inadequate exposure of glottis if space
reduced/narrowed as tongue is pushed in
here
◦ MTD
◦ RHTMD
◦ MSD
◦ MHD

34. THYROMENTAL DISTANCE (PATIL TEST)
Distance from the tip of thyroid cartilage to
the tip of mandible(mental symphysis)
Neck fully extended
• > 6.5cm: no problem with L/I
• 6.0 – 6.5cm: without other concomitant
anatomical problems L&I are difficult but
possible
• < 6cm: Laryngoscopy may be impossible

36. RATIO OF HEIGHT TO THYROMENTAL DISTANCE
(RHTMD)
Modification to improve the accuracy
Useful bedside screening test
very sensitive predictor of difficult
laryngoscopy
RHTMD < 23.5 –easy laryngoscopy
MENTOSTERNAL DISTANCE : (SAVVA TEST)
Head in full extension and mouth closed
<12.5cm predicts difficult laryngoscopic
intubation
sensitivity of test is 0.82 and specificity is 0.89
Considered single best predictor
MODIFIED MEASURMENT

37. Distance between mentum and the hyoid
bone
Grade I: > 6.0 cm
Grade II: 4.0 – 6.0 cm
Grade III: < 4.0 cm
Grade III may be associated with impossible
laryngoscopy and intubation.

38. INDIRECT LARYNGOSCOPIC VIEW
 Grade 1: Vocal cords visible
 Grade 2: Posterior commisure visible
 Grade 3: Epiglottis visible
 Grade 4: No glottic structures visible
Grade 3 & 4: Predicted difficult
This correlates with Cormack and Lehane’s
laryngoscopic view

39. DIRECT LARYNGOSCOPY VIEW
Based on Cormack & Lehane
classification
◦ Grade I: Visualization of entire vocal cords
◦ Grade II: Visualization of posterior part of
laryngeal aperture
◦ Grade III: Visualization of epiglottis
◦ Grade IV: No glottic structures seen
Not a grading system for everyday
recording of view at laryngoscopy

41.  Grade I : Same as C&L
 Grade II a: Partial view of glottis
 Grade II b: Arytenoids or posterior
part of the vocal cords only just
visible
 Grade III : Same as C&L
 Grade IV : Same as C&L

42. Percentage Of Glottic Opening
Seen during D/L
 100% : Entire glottic aperture visualized
 33% : Lower one third of VC & arytenoids
 0% : No glottic structures visible

44. Patient to hold the head erect, facing
directly to the front  maximal head
extension  angle traversed by the
occlusal surface of upper teeth
◦ Grade I : > 35°
◦ Grade II : 22-34°
◦ Grade III : 12-21°
◦ Grade IV : < 12°
For greater accuracy a goniometer is used
to measure the angle traversed by upper
teeth

46. Sniffing Position (Mc Gills Position)
Normal Alanto occipital extension 35
degrees

47. Placing two fingers on chin and occipital
protuberance
Result
◦ Finger on chin higher than one on occiput 
normal cervical spine mobility
◦ Level fingers  moderate limitation
◦ Finger on the chin lower than the second 
severe limitation
Prayer sign
Palm print test

48. 1. Can place 3 finger breaths between the
teeth
2. Between the mandibular genu and hyoid
bone
3. Between thyroid cartilage and sternal
notch

49. Difficult L&I multifactorial problem
No simple test can predict difficult intubation
accurately
Effective prediction requires a combination of
tests
◦ Wilson Scoring System
◦ The Intubation Difficulty Scale (IDS)
◦ Benumoff’s 11parameter analysis

50. Risk factor Score
1. Weight 0
1
2
< 90 kg
90-100 kg
> 110 kg
2. Head & neck movement 0
1
2
Above 90°
About 90° (i.e. ± 10°)
Below 90°
3. Jaw movement 0
1
2
IG > 5 cm or S. Lux >
0
IG < 5 cm S. Lux = 0
IG < 5 cm S. Lux < 0
4. Receding mandible 0
1
2
Normal
Moderate
Severe
5. Buck teeth 0
1
2
Normal
Moderate
Severe
WILSONS SCORING SYSTEM

51. Subjective and Objective criteria
Intubation difficulty defined degree of
divergence from a predefined “ideal
intubation”
 performed without effort on the 1st attempt
 practiced by one operator
 using one technique
 full visualization of the laryngeal aperture and
vocal cords abducted.

52. PARAMETER SCORE
1. No. of attempts > 1 N1
2. No. of operators > 1 N2
3. No. of alternative techniques N3
4. Cormack Grade I N4
5. Lifting force required
Normal N5=0
sed N5=1
6. Laryngeal pressure
Not applied N6=0
Applied N6=1
7. Vocal cord mobility
Abduction N7=0
Adduction N7=1
TOTAL IDS = Sum of scores N1–
N7

53. Rules for calculating IDS Score
N1 Every additional attempt adds 1
pt
N2 Every additional operator adds 1
pt
N3 Each alternative technique adds
1 pt:
N4 Apply Cormack grade
N6 Sellick’s maneuver adds no
points IDS Score Degree of Difficulty
0 Easy
0 < IDS < 5 Slight difficulty
5 < IDS Moderate to Major difficulty
IDS =  Impossible intubation

54. 1. Inter-incisor gap : >3cm
2. Buck teeth +/-
3. Length of incisor: <1.5cm
4. Upper Lip Bite
5. MMP class
6. Palate: arching / narrowing
7. TMD: >6cm
8. Mandibular compliance
9. Neck length: sufficient
10.Neck diameter: thin or thick
11.Neck movement

55. Look –anatomical features suggestive of difficulty
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-flexion
extension

56. follow a simple mnemonic - FOAM for assessing
the difficult bag-mask ventilation.
F: Facial hairs, piercings & deformities [but not
limited to] such as burn scarring, growths,
emaciated face precluding adequate fit of face
mask.
O: Obesity [BMI > 30], Obstructed breathing
[history of snoring].
A: Aged > 60 years, Absence of teeth.
M: Movement restriction of head & neck
[Extension: cannot look at the ceiling without
raising eyebrows; Flexion: cannot touch the chin
to the chest] and inability to slide the lower jaw
incisors beyond the maxillary jaw incisors.

57. HAEM for assessing and predicting difficult
laryngoscopy & tracheal intubation in patients.
H: History [but not limited to] of past difficult
laryngoscopy & intubation, snoring, joint
disorders, diabetes mellitus.
A: Appearance [but not limited to] such as
short neck, poor dental status, obesity, small
or large chin, buck teeth, facial trauma,
facial/oral swelling, tumor.

58. E: Examination [3-6-12-24]:
3: Assess oral opening for rigid laryngoscopy – <3 cm
inter-incisor space is inadequate for smooth
introduction of the laryngoscope blade.
6: Measure the ability of the mandibular space to
accommodate the tongue – <6 cm space between the
mentum and the thyroid notch is inadequate for
compressing the tongue during rigid laryngoscopy.
12: Assess ability to extend the head fully, thereby
aligning airway axis for easy laryngoscopy & intubation
– <12 cm distance between sternal notch and mentum
in a maximally extended head with mouth closed is
associated with difficult laryngoscopy.
24: Assess ratio of the patient height to thyromental
distance [in cm] for predicting easy laryngoscopy – a
ratio of >24 is abnormal and points to difficult
laryngoscopy & intubation.
M: Mobility of the head & neck and Mallampati grade II
or greater.

59. DROP for predicting the difficult supraglottic
device placement or subsequent ventilation
via it.
D: Disrupted upper airway [but not limited to]
trauma, ingestion of caustics.
R: Restricted mouth opening [<2 cm].
O: Obstruction of the upper airway [but not
limited to] mass, foreign body, edema.
P: Poor lung or thoracic compliance.

60. Lateral cervical x-ray film : head in neutral
position
ANTERIOR ATLANTO DENTAL INTERVAL (AADI)
 Between posterior surface of arch of C1
 Anterior surface of Dens
 Normal < 3mm adults <5mm Children

62. Limits the extension of head on neck
Longer the A-O gap, more space for mobility
of head
Radiologically there is reduced space between
C1 and occiput
<5mm distance

63. POSTERIOR DEPTH OF THE MANDIBLE :
Distance between bony alveolus behind 3rd
molar tooth & lower border of the mandible
>2.5 cm predicts difficult L&I
RATIO OF EFFECTIVE MANDIBULAR
LENGTH TO POSTERIOR DEPTH
<3.6 predicts difficult L&I
DIFFERENT PATHOLOGIES ACQUIRED OR
CONGENITAL CAN BE PICKED UP

66. Seldom used clinically. These are:
a) Flow volume loops
b) Acoustic reflectometry
c) Ultrasound
d) MRI

67. TEST SENSTIVITY SPECIFICITY PPV
Mouth Opening 26-47 94-95 7-25
Jaw protrusion 17-26 95-96 5-21
Mallampati (original) 62 25 16
Mallampati (modified) 65-81 66-82 8-9
TMD 62 25 16
TMD + MMP 81 98 64
Mento sternal distance 82 89 27
Neck movement 10-17 98 64
Wilsons scoring 42-55 86-92 6-9
Indirect Laryngoscopy 69 98 31

68. No single airway test provides a high index of
sensitivity and specificity
Combination of multiple tests a MUST!
Some with difficult airway will remain
undetected
Pre-formulated and practiced plans for
unanticipated difficult airway