2. INTRODUCTION
Expertise in airway management is essential in every medical speciality.
Maintaining a patent airway is essential for adequate oxygenation & ventilation &
failure to do so, even for a short duration can be life threatening.
Respiratory events are the second common injuries in anaesthesia practise.
Causes of respiratory related injuries are
a) Inadequate ventilation
b) Esophageal intubation
c) Difficult tracheal intubation.
Difficult tracheal intubation accounts for 17% of the respiratory related injuries &
results in significant morbidity & mortality.
Estimated that upto 28% of all anaesthetic related deaths are secondary to the
inability to mask, ventilate or intubate.
A trainee in airway management requires an average of 29 exposures to difficult
airway to become competent ( special reference to obstetrics)
3. WHY AIRWAY ASSESSMENT
Optimal patient preparation.
Proper selection of equipment & technique.
Participation of personnel experienced in the difficult airway management.
4. BEFORE GETTING STARTED!
DIFFICULT AIRWAY- Clinical scenario in which a conventionally trained
anaesthesiologist experiences difficulty with
I. Face mask ventilation
II. Tracheal intubation
III. Both.
6. DIFFICULT MASK VENTILATION
1. It is not possible for an unassisted anesthesiologist to maintain oxygen saturation more than 90%
using 100% oxygen & positive pressure mask ventilation in a patient whose oxygen saturation was more
than 90% before anesthetic intervention.
And/ or
2. It is not possible for the unassisted anesthesiologist to prevent or reverse signs of inadequate
ventilation during positive pressure mask ventilation.
2 MAIN REASONS FOR DIFFICULT MASK VENTILATION
1.Inadequate seal
2.Inadequate patency of airway.
INCIDENCE- 0.08%-5%
DIFFICULT MASK VENTILATION has been now redefined by ASA (2022) as
It is not possible to provide adequate ventilation ( confirmed by ETCO2 detection)because of one or
more following problems
1. Inadequate mask seal
2. Excessive gas leak
3. Excessive resistance to ingress /egress of gas.
7. DIFFICULT LARYNGOSCOPY
Not possible to visualize any portion of the vocal cords after multiple attempts at
conventional laryngoscopy ( Cormack & Lehane’s grade IV)
ASA (2022) new definition- no visualization of vocal cords after multiple attempts at
laryngoscopy.
8. DIFFICULT INTUBATION
More than 3 attempts
Longer than 10 minutes
Failure of optimal best attempt.
FAILED INTUBATION
Failure of passage of endotracheal tube after multiple intubation attempts.
ASA (2022) new definition of difficult or failed intubation: tracheal intubation
requires multiple attempts or tracheal intubation fails after multiple attempts.
9. INTUBATION ATTEMPT: Intubation activities occurring during a single continuous
laryngoscopy manoeuvre.
RAPID SEQUENCE INTUBATION:Administration of a fixed dose of induction agent &
short acting muscle relaxant after pre-oxygenation & intubation of trachea
without interposed assisted ventilation.
It is done in non fasting patients to reduce risk of aspiration of gastric contents.
10. ANATOMY OF AIRWAY IN ADULTS
It refers to the normal passage for air entry & exit in a human being for efficient gas exchange at
the lungs.
It may be divided into
1.Upper airway
2.Lower airway
UPPER AIRWAY- Comprises of mouth/oral cavity, nasal cavity,pharynx,nasopharynx
oropharynx & the larynx
1. Mouth/Oral cavity- Extends from the mouth opening to anterior tonsillar pillars.
2. Nasal cavity- Extends from the naris to the end of the turbinates.
3. Nasopharynx : It extends from the posterior end of turbinates to posterior pharyngeal wall
above soft palate.
4. Oropharynx : It extends from soft palate above to epiglottis below & anteriorly from anterior
tonsillar pillar to posterior pharyngeal wall.
5. Larynx :It extends from laryngeal inlet [C3-C4 in adults] to lower border of cricoid cartilage [ C6
in adults]. Larynx includes 3 paired & 3 unpaired cartilages
3 large Unpaired cartilages are cricoid, thyroid & epiglottis
3 Paired smaller cartilages are arytenoids, corniculate & cuneiform.
Thyroid is the largest of the laryngeal cartilages having 2 alae which meets anteriorly at an angle of
90 degrees in males & 120 degrees in females. Vocal cords are attached to its middle.
The cricoid is the only complete ring cartilage.
11. UPPER AIRWAY:
most vulnerable to obstruction because in
an unresponsive or anesthetized patient
there occurs loss of tone in throat muscles due
to which tongue falls back & occludes the airway
at the level of pharynx & allows the epiglottis to
occlude the airway at the level of larynx.
12.
13. DISEASE STATES OF NECK & SPINE
RESPONSIBLE FOR DIFFICULT AIRWAY :
NECK : 1. Large goiters
2. abscess
3. skin contractures
SPINE : 1.limitation of movement- CONGENITAL- Klippel-Feil syndrome
ACQUIRED- surgical fusion, # of cervical
vertebrae.
2. cervical spine instability- Down Syndrome
PATHOLOGIC STATES AFFECTING HEAD EXTENSION
1. Ankylosing spondylitis
2. Rheumatoid arthritis
3. Cervical spondylitis
4. Cervical fusion
5. Cystic hygroma
6. Fibrosis secondary to burns & irradiation
14. LOWER AIRWAY
It includes trachea ,bronchi in bronchioles, which after multiple divisions finally terminate into
alveoli.
TRACHEA – Trachea extends from lower border of cricoid cartilage [ C6] to its division into 2 main
bronchi [T4]. It is 11-13 cm long.
Carina is a very sensitive structure
& its stimulation can evoke un-
wanted responses.
Tubes/catheters should be kept
away from it.
The trachea divides at carina into
right main bronchus at approx. 20-25
degrees angle & the left main bronchus at
approx. 45-55degrees angle.
15. LOWER AIRWAY PATHOLOGY FOR
DIFFICULT AIRWAY:
1.TRACHEAL : Tracheitis , tracheoesophageal fistula, tracheal stenosis
Foreign bodies, tracheomalacia
2. BRONCHIAL TREE PATHOLOGY : Mediastinal masses, foreign body aspiration,
bronchial tumors.
16. MEAN AIRWAY DISTANCES/ANGLES IN
ADULTS OF INTEREST TO THE
ENDOSCOPIST :
1. Mean distance from lips to carina= 28.5 [M] & 25.2[F]
2. Mean distance from base of nose to the carina =31[M] & 28.4[F]
3. Mean angle of right main bronchus =20-25 degrees
4. Mean angle of left main bronchus =40-50 degrees.
REQUIREMENTS OF NECK WHILE INTUBATION OR LARYNGOSCOPY
: 1. HEAD EXTENSION= >80-85 degrees- ask the patient to look at the ceiling
without raising eyebrows to test A-O joint function.
2. NECK FLEXION =>25-30 degrees –ask the patient to
touch his manubrium sternii with his chin & assess the movement
3. HEAD/NECK ROTATION= >70-75 degrees.
NECK FLEXION ON CHEST BY 25-30 DEGREES & A-O JOINT EXTENSION BY 85
DEGREES IS CALLED SNIFFING OR MAGILL’S POSITION – gives an easy
laryngoscopic view.
21. EXAMINE THE MOUTH
1. IS THE MOUTH OPENING LIMITED ?
2. IS MOUTH NARROW ?
3. IS INTRA ORAL CAVITY SMALL ?
4. IS VIEW OF FAUCES POOR ?
5. IS TONGUE LARGE ?
5. IS THERE CLEFT LIP OR PALATE ?
6. LARGE TEETH ?
7. UPPER INCISORS PROMINENT ?
8. ANY PROSTHESES OR BRIDGES ?
PATHOLOGICAL STATES FOR DIFFICULTY IN MOUTH
OPENING:
1. Ankylosing spondylitis
2. Rheumatoid arthritis
3. TM joint fixity
4. Scleroderma
5. Local acute infections
6. Localized tumors
7. Tongue flaps
8. Circumoral burns with scarring
23. In any emergency no single indices can
predict difficult airway with 100% sensitivity
unless the abnormality is gross.
24. INDIVIDUAL INDICES FOR DIFFICULT MASK
VENTILATION :
1. PRESENCE OF BEARD : Spreading opsite film over the beard or applying
Vaseline is recommended to improve mask seal.
2. OBESITY
3. ABNORMALITY OF TEETH
4. ELDERLY PATIENTS > 55yrs of age
5. SNORERS – Application of gentle but continuous positive airway pressure (5-
10 cm H2O) while ventilating to keep airway patent.
6. HAIR BUN- Undo bun prior to positioning.
7. JEWELERY & FACIAL PIERCING: Remove them
25. GROUP INDICES FOR DIFFICULTY TO FACE
MASK VENTILATE : OBESE
1. O : OBESE [ Body mass index more than 26kg/m2]
2. B : BEARDED
3. E : ELDERLY [ Than 55yrs]
4. S : SNOARERS
5. E : EDENTULOUS [ No teeth] [= BONES]
Another one to remember : MOANS
This is identical to BONES except M : Mask seal difficulty due to receding mandible, syndromes with facial
abnormalities, burns, strictures.[ also may be due to small hands of the trainer, wrong size mask, oddly shaped
face,bushy beard,blood/vomit]
O : OBESITY- use 2 hands for mask seal & jaw thrust, avoid pushing in on soft tissues under jaw
A : ADVANCED AGE
N : NO TEETH- place gauge at site of leak as cheeks fall inward or put gauge inside mouth to ‘puff out’ cheek
S : SNORER.
26. PREDICTORS OF DIFFICULT
LARYNGOSCOPY & INTUBATION
INDIVIDUAL INDICES : 1. Physical examination indices
2. radiological indices
3. advanced indices
GROUP INDICES : 1. WILSON’S SCORE
2. Benumof’s analysis
3. Saghei & Safavi’s test
4. LEMON ASSESSMENT
5. Arne’s simplified score
6. Magboul’s 4 M’s
7. 4 D’s
27. INDIVIDUAL INDICES:
1. PHYSICAL EXAMINATION INDICES:
a. ANATOMICAL CRITERIA : i. relative to tongue/pharyngeal
size
ii. atlanto-occipital joint extension
iii. mandibular space
iv. TMJ assessment
b. DIRECT LARYNGOSCOPY
28. a. ANATOMICAL CRITERIA
:
i. RELATIVE TO TONGUE/PHARYNGEAL SIZE [ MALLAMPATI
CLASSIFICATION & SCORE ] :As the class increases there is difficulty
in intubation.
29. PRE-REQUISITES FOR MALLAMPATI TEST :
1.See for free movement of – a. head on cervical spine
b. joints of cervical spine permitting
flexion & extension of neck
c. temperomandibular joint to open mouth
widely.
2. Have patient sit up, with head protruding forward [ sniffing position] & stick out
tongue without phonation which lowers the grade by one step [ grade 2 becomes
grade 1]
3. The observer’s eye should be at the level of the patient’s open mouth.
MAY BE UNABLE TO ASSESS PROPERLY IN AN EMERGENCY SITUATION.
MODIFIED VERSION IS TO USE A LARYNGOSCOPE BLADE LIKE A TONGUE BLADE TO
VISUALIZE OROPHARYNX.
30. ii.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 & the examiner estimates the angle
traversed by the occlusal surface of the upper teeth
Visual assessment or using 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 & laryngeal axes into a straight line
Limited A-O joint extension – spondylosis, rheumatoid arthritis, halo-jacket
fixation & in patients with symptoms indicating nerve compression with
cervical extension.
GRADES III & IV : DIFFICULT LARYNGOSCOPY
31. DELILKAN’S TEST
If the left index finger remains at the same level
of the right or lower then extension is abnormal
32. DIFFICULT LARYNGOSCOPY OR INTUBATION
A CLUNK is felt as the head starts to extend & the movement stops.
33. 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 DIABETES.
It represents cervical spine immobility & a potential for a difficult
intubation [ STIFF JOINT SYNDROME IN JUVENILE DIABETES ]
34.
35. iii.ASSESSMENT OF MANDIBULAR SPACE :
THYROMENTAL DISTANCE [ PATIL’S TEST ]
HYOMENTAL DISTANCE
STERNOMENTAL DISTANCE [ SAVVA TEST]
37. LIMITATIONS – A. Little reliability in prediction unless comb-
-ined with other tests. [ grade 3 or 4 mallampati who also has
a thyromental distance of less than 7cm is likely to present with
difficulty in intubation ]
B. Variation according to height, ethnicity
MODIFICATIONS TO IMPROVE THE ACCURACY :
1. Ratio of height to thyromental distance [ RHTMD]
2. Useful bedside screening test
3. RHTMD > 23.5 very sensitive predictor of difficult laryngoscopy.
39. STERNOMENTAL DISTANCE [SAVVA TEST]
Distance from the upper border of the manubrium to the tip of mentum, neck
fully extended, mouth closed.
Mininal acceptable value – 12.5
SINGLE BEST PREDICTOR of difficult laryngoscopy & intubation [ has high
sensitivity & specificity].
40.
41. iv.ASSESSMENT OF TMJ FUNCTION :
The joint exhibits 2 futions
Rotation of the condyle in the submandibular cavity
forward displacement of the condyle
The first movement is responsible for 2-3cm mouth opening & the second is
responsible for further 2-3cm mouth opening.
1. SUBLUXATION OF MANDIBLE
Index finger is placed in front of the tragus & the thumb is placed in front of the
lower part of the mastoid process.
Patient is asked to open his mouth as wide as possible.
Index finger in front of tragus can be indented in its space & the thumb can feel
the sliding movement of the condyle as the condyle of the mandible slides
forward.
2. Ask the patient to open his mouth wide & place 3 fingers (
index, middle & ring fingers) in the opening. If done,> 5cm & adequate for
laryngoscopy.
44. SIGNIFICANCE : Assessment of mandibular movement &
dental architecture.
Less inter observer variability.
45. THYROID- FLOOR OF MOUTH DISTANCE
1. Tells about position of larynx
2. Larynx placed higher in the neck in obese patients causes difficult
laryngoscopy.
3. Larynx is normally placed if the patient can place 2 fingers between top
thyroid cartilage & floor of mouth.
46. ADEQUACY OF OROPHARYNX FOR
LARYNGOSCOPY & INTUBATION
1. MALLAMPATI GRADING [SAMSOON & YOUNG MODIFICATION] : CLASS III & IV
signifies angle between base of tongue & laryngeal inlet is more acute & not
conductive for easy laryngoscopy. [ good predictor in pregnancy, obesity &
acromegaly]
2. NARROWNESS OF THE PALATE
A narrow, high arched palate offers
Very little space for laryngoscopy
& endotracheal intubation.
47. ASSESSMENT FOR QUALITY OF GLOTTIC VIEW
DURING LARYNGOSCOPY
1. INDIRECT MIRROR LARYNGOSCOPIC VIEW- classification
• Complete vocal cords visible
• Posterior commissure visible
• Epiglottis visible
• No glottis structures visible.
2. DIRECT LARYNGOSCOPY “ AWAKE LOOK” – CORMACK & LEHANE GRADING
3. GRADING EASE OF INTUBATION-
• GRADE 1- No extrinsic manipulation of larynx is required
• GRADE 2- External manipulation of larynx is necessary to intubate.
• GRADE 3- Intubation possible only when aided by a stylet.
• GRADE 4- Failed intubation
4. POGO [PERCENTAGE OF GLOTTIC OPENING] SCORING-
Entire glottic structure visualized – 100%
No glottis structures are visible not even arytenoids -0%
Lower third of vocal cords & arytenoids visible- 33%
48. b.DIRECT LARYNGOSCOPY
CORMACK & LEHANE grading
Grade I : FULL APERTURE IS VISIBLE [A]
Grade II : LOWER PART OF CORDS VISIBLE [B]
Grade III : ONLY EPIGLOTTIS VISIBLE [C]
Grade IV : EPIGLOTTIS NOT VISIBLE [D]
49. COOK has further subdivided CORMACK & LEHANE’S GRADE II & III
into IIa,IIb,IIIa,IIIb.
Here grade I & IIa patients can be directly intubated
Grade IIb & IIIa would require bougie
Grade IIIb & IV cannot be intubated using conventional laryngoscope
with bougie but would require alternative specialized techniques.
50.
51.
52.
53. 2.RADIOLOGICAL INDICES:
1. X-RAY NECK (LATERAL) predicting difficult intubation or laryngoscopy
• 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
2. CT SCAN
• Tumors of floor of mouth,pharynx,larynx
• Cervical spine trauma,inflammation
• Mediastinal mass
3.HELICAL CT –Exact location & degree of airway compression
54. 3.ADVANCED INDICES
1. FLOW VOLUME LOOP- In this, forced expiratory volume & forced inspiratory volume are
recorded in quick succession on a spirogram. Flow plotted in vertical axis & volume on
horizontal. The shape of flow-volume loop indicates type of obstruction
2.ACOUSTIC RESPONSE MEASUREMENT
3.USG GUIDED- The sono anatomy of the upper airway structures such as tongue, hyoid-
thyroid-cricoid cartilages,epiglottis tracheal cartilages & esophagus can be identified in
normal & difficult airway patients.
It is simple, non-invasive & easily portable in places like OT, CCU
Failure to visualize hyoid bone using sublingual usg predicts difficult intubation.
A 1.69 cm thickness or greater at hyoid bone level & a 3.47cm thickness or greater at thyrohyoid
membrane corresponds to difficult airway.
Increased tongue thickness >6.1cm =predictor of difficult airway in usg of tongue
Skin epiglottis distance by usg <18mm- difficult airway
Usg in obese patients to identify difficult intubation- mean pretracheal tissue 28mm at the level
of vocal cords= difficult airway
Anterior neck thickness .2.8cm at the level of hyoid bone & thyrohyoid membrane compared to
vocal cords = predictor of difficult laryngoscopy in obese.
Besides capnography being gold standard of diagnosing correct ET tube placement, USG confirms
ETT position in trachea when 2 hyperechoic lines are seen as double tract or double lumen sign.
4.CT/MRI
5. FLEXIBLE BRONCHOSCOPE
55. GROUP INDICES
1.WILSON’S SCORE: Head movement assessed with pencil
taped to a patient’s forehead
IG – Inter-incisor gap measured with
mouth fully open.
Slux- maximal forward protrusion of
the lower incisors beyond the upper
incisors.
56. 2.BENUMOF’S 11 PARAMETER ANALYSIS:
PARAMETER MINIMUM ACCEPTABLE VALUE
1.BUCK TEETH( overriding of maxillary
teeth on the mandibular teeth) NO OVERRIDING.
2. LENGTH OF UPPER INCISORS <1.5cm
3. INTER-INCISOR GAP >3cm
4. PALATE CONFIGURATION NO ARCHING/NARROWNESS
5. MALLAMPATI CLASS CLASS II OR LESS
6.VOLUNTARY PROTRUSION OF MANDIBULAR
TEETH ANTERIOR TO MAXILLARY TEETH MANDIBULAR TEETH PROTRUDED BEYOND
MAXILLARY TEETH
7. TM DISTANCE >5cm
8. SUBMANDIBULAR SPACE COMPLIANCE SOFT TO PALPATION
9.NECK THICKNESS QUALITATIVE [>33cm DI]
10.LENGTH OF NECK >8cm
11. HEAD/NECK MOVEMENT SNIFFING POSITION( HEAD
EXTENSION 85 DEGREES & NECK FLEXION 35
DEGREES)
4-2-2-3 RULE
4STEPS ON TEETH [1,2,3,6]
2 STEPS INSIDE MOUTH[4,5]
2 STEPS FOR MANDIBULAR SPACE]
3 STEPS IN NECK EXAMINATION
[9,10,11]
64. 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 – anticipate difficulty
66. NECK MOBILITY
Normal head & neck movement includes an extension >80-85 degrees , fexion
of >25-30 degrees & rotation of>70-75 degrees.
STEPS TO TELL PATIENT TO ELICIT THE ABOVE :
• ASK PATIENT TO PUT CHIN ON CHEST (NECK FLEXION) & LOOK AT THE
CEILING (HEAD EXTENSION AT A-O JOINT)
PROBLEMS :
1. CERVICAL SPINE IMMOBILIZATION
2. ANKYLOSING SPONDYLITIS
3. RHEUMATOID ARTHRITIS
4. HALO FIXATION
69. Factors responsible for difficult airway in peadiatric patients : The
difference between infant & adult airway includes position of
larynx in the neck, tongue size, epiglottis size, size of head
relative to body, neck length, nares size & the location of the
narrowest point. 1. Infant’s larynx is located higher in the neck at C3-C4 level which
causes tongue to shift more superiorly close to palate which apposes
the palate & cause airway obstruction
2. Infant’s tongue is larger in proportion to the size of mouth than in
adults causing obstruction of upper airway during sedation,
inhalation induction of anaesthesia or emergence from anaesthesia
3.The epiglottis in an infant’s airway is relatively &larger,stiffer &
more omega shaped & typically angled in a more posterior position
thereby blocking visualization of cords during laryngoscopy
4. In infants it is necessary to lift the epiglottis with the tip of the
blade of laryngoscope to visualize the vocal ciords.
5. The narrowest portion of an infant’s airway ia at the cricoid
cartilage whereas in adults it is at vocal cords.
6. An infant’s head & occiput are relatively larger than an adult’s so
proper positioning with head extended at C1-C2 & neck flexed at C6-
C7 requires a shoulder roll to establish optimal facemask ventilation
7. Infant’s nares are relatively smaller offering resistance to airflow
& increase work of breathing.
70. HISTORY & PHYSICAL EXAMINATION TO ASSESS
PAEDIATRIC AIRWAY:
1. HISTORY- Any complaints of snoring, apnea, day time somnolence, stridor,
hoarse voice & prior surgery or radiation treatment to face or neck
2. PHYSICAL EXAMINATION- a. evaluate size & shape of head, size & symmetry
of mandible, size of tongue, shape of palate, prominence of upper incisors,
range of motion of jaw, head & neck.
b. presence of retractions
c. breath sounds- crowing on inspiration is indicative of extrathoracic
airway obstruction
noise on exhalation is due to intrathoracic lesions.
d. obtaining blood gas & O2 saturation to determine patient’s ability to
compensate for airway problems.
71. COPUR SCALE OF AIRWAY ASSESSMENT IN
PAEDIATRIC PATIENTS
PREDICTION POINTS
5-7= EASY NORMAL INTUBATION
8-10= LARYNGEAL PRESSURE MAY HELP
12= INCREASED DIFFICULTY,FIBREOPTIC
MAY BE PREFERRED
12= DIFFICULT INTUBATION
16=DANGEROUS AIRWAY
SCORE >10 predict difficult intubation
If Hyomental distance is one finger in
infants
& 2 fingers in children – potential
displacement area is adequate
72. Just to recall
1. RULE OF 1-2-3: 1 finger breadth for sublaxation of mandible
2 finger breadth for adequacy of mouth opening
3 finger breadth for hyomental distance
In an emergency situation this test can be performed within 15
seconds to assess TMJ function, mouth opening & SM space.
Difficulty in 2 or more of these components require detailed
examination.
2. RULE OF 1-2-3-4-5: 4 finger breadth for thyromental distance
5 movements- ability to flex head upto
manubrium sterni, extension of AOJ, rotation of head along with
right & left movement of head to touch the shoulder.
3. RULE OF 3-3-3: 3 finger in interdental space
3 finger hyomental distance
3 finger between thyroid & sternum.
73. The difficult airway is something one
anticipates, the failed airway is somethimg
one experiences.
Develop your skills & ways to assess the airway
There are a lot of scores & numbers
Adapt what suits you… what you can remember & apply