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Wesam Farid MousaAssist prof Anesthesia

& ICUDammam University ,

KSA

Why it is a basic requirement ??

Difficult intubation results in significant morbidity and mortality

Prediction of the difficult airway allows time for proper selection of equipment,

technique and personnel experienced in difficult airways

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.”

definition ofDifficult 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.

definition ofDifficult intubation

• More than 3 attempts in 10 minutes time

• Failure of optimal best attempt

The canadian Society of Anesthesiologists (CSA) definition:

• It is not possible to visualize any portion of the vocal cords with conventional laryngoscopy –

• Intubation requires more than one attempt, a change in the blade, an adjunct to direct laryngoscopy or use of alternative devices

Prevalence

• Difficult face mask– 0.1% - 5%

• Difficult intubation– 1-2% of normal surgical population– 50% of rheumatic cervical disease

Airway assessment

• History– Patient/notes/chart: Surgery/burns Concurrent disease

• General examination– Do they just look difficult? Obese or pregnant - Beards

– Airway examination• 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)

• Specific tests/indices• Investigations.

- Nasoendoscopy X-ray - CT/MRI - Flow volume loop• Mask ventilation precedes laryngoscopy

1.Obese (body mass index >30kg/m2) 2.Bearded 3.Elderly (older than 55 y) 4.Snorers 5.Edentulous

1)Bearded2)Obese3)No teeth4)Elderly5)Snorers

1)Mask seal difficult 2)Obesity3)Advanced age4)No teeth5)Snorer

1)Bearded2)Obese3)No teeth4)Elderly5)Snorers

Predictors of difficult intubationIndividual indices

-Physical examination indices- radiological indices- advanced indices

1. Atlanto-occipital movement

2. Warning sign of DELIKAN

3. Prayer sign

4. Palm Print test

5. Assessment of TMJ function

6. Assessment of mandibular space: thyrohyoid, thyromental, hyomental

7. Inter-incisor gap

8. Sternomental distance (SAVVA TEST)

9. Upper lip bite /catch test

10.Mallampati Score

11.Grading at direct laryngoscopy CORMACK - LEHANE

Predictors of difficult intubationGroup indices

-Physical examination indices-radiological indices-advanced indices1. Wilson’s score

2. Saghei & safavi test

3. Lemon assesment

4. Arne’s simplified score

5. Magboul’s 4 M’s

Predictors of difficult intubationIndividual indices

-Physical examination indices- radiological indices- advanced indices

1. Atlanto-occipital movement

2. Warning sign of DELIKAN

3. Prayer sign

4. Palm Print test

5. Assessment of TMJ function

6. Assessment of mandibular space: thyrohyoid, thyromental, hyomental

7. Inter-incisor gap

8. Sternomental distance (SAVVA TEST)

9. Upper lip bite /catch test

10.Mallampati Score

11.Grading at direct laryngoscopy CORMACK - LEHANE

It assesses feasibility to make sniffing or Magill position for intubation i.e. alignment of oral, pharyngeal and laryngeal axes into an arbitrary straight line.

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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

Grades 3 and 4 : Difficult laryngoscopy

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 & extension movement if within the normal range, three axes (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

Again

Predictors of difficult intubationIndividual indices

-Physical examination indices- radiological indices- advanced indices

1. Atlanto-occipital movement

2. Warning sign of DELIKAN

3. Prayer sign

4. Palm Print test

5. Assessment of TMJ function

6. Assessment of mandibular space: thyrohyoid, thyromental, hyomental

7. Inter-incisor gap

8. Sternomental distance (SAVVA TEST)

9. Upper lip bite /catch test

10.Mallampati Score

11.Grading at direct laryngoscopy CORMACK - LEHANE

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.

Predictors of difficult intubationIndividual indices

-Physical examination indices- radiological indices- advanced indices

1. Atlanto-occipital movement

2. Warning sign of DELIKAN

3. Prayer sign

4. Palm Print test

5. Assessment of TMJ function

6. Assessment of mandibular space: thyrohyoid, thyromental, hyomental

7. Inter-incisor gap

8. Sternomental distance (SAVVA TEST)

9. Upper lip bite /catch test

10.Mallampati Score

11.Grading at direct laryngoscopy CORMACK - LEHANE

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 diabetics

This represents:- cervical spine immobility and the potential for a difficult endotracheal intubation

Predictors of difficult intubationIndividual indices

-Physical examination indices- radiological indices- advanced indices

1. Atlanto-occipital movement

2. Warning sign of DELIKAN

3. Prayer sign

4. Palm Print test

5. Assessment of TMJ function

6. Assessment of mandibular space: thyrohyoid, thyromental, hyomental

7. Inter-incisor gap

8. Sternomental distance (SAVVA TEST)

9. Upper lip bite /catch test

10.Mallampati Score

11.Grading at direct laryngoscopy CORMACK - LEHANE

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.

Which grade you see?

Predictors of difficult intubationIndividual indices

-Physical examination indices- radiological indices- advanced indices

1. Atlanto-occipital movement

2. Warning sign of DELIKAN

3. Prayer sign

4. Palm Print test

5. Assessment of TMJ function

6. Assessment of mandibular space: thyrohyoid, thyromental, hyomental

7. Inter-incisor gap

8. Sternomental distance (SAVVA TEST)

9. Upper lip bite /catch test

10.Mallampati Score

11.Grading at direct laryngoscopy CORMACK - LEHANE

TM joint exhibits 2 functions.

*Rotation of the condyle

*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 MANDIBLESUBLUXATION OF THE MANDIBLEIndex 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.

Significance-Class B and C: difficult laryngoscopy

Predictors of difficult intubationIndividual indices

-Physical examination indices- radiological indices- advanced indices

1. Atlanto-occipital movement

2. Warning sign of DELIKAN

3. Prayer sign

4. Palm Print test

5. Assessment of TMJ function

6. Assessment of mandibular space: thyrohyoid, thyromental, hyomental

7. Inter-incisor gap

8. Sternomental distance (SAVVA TEST)

9. Upper lip bite /catch test

10.Mallampati Score

11.Grading at direct laryngoscopy CORMACK - LEHANE

Assessment of mandibular spaceThyromental distance: ”PATIL’S TEST”

Patient seated, head extended mouth closed,

distance that exists between the thyroid cartilage (upper recess) and the lower border of the chin

is evaluated

Thyromental Distance

If the thyromental distance is short, <6 cm or <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

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

HYO MENTAL DISTANCEHYO MENTAL DISTANCE

Distance between mentum and hyoid

•Grade I : > 6cm•Grade II: 4 – 6cm•Grade III : < 4cm – Difficult laryngoscopy & Intubation

Predictors of difficult intubationIndividual indices

-Physical examination indices- radiological indices- advanced indices

1. Atlanto-occipital movement

2. Warning sign of DELIKAN

3. Prayer sign

4. Palm Print test

5. Assessment of TMJ function

6. Assessment of mandibular space: thyrohyoid, thyromental, hyomental

7. Inter-incisor gap

8. Sternomental distance (SAVVA TEST)

9. Upper lip bite /catch test

10.Mallampati Score

11.Grading at direct laryngoscopy CORMACK - LEHANE

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

Predictors of difficult intubationIndividual indices

-Physical examination indices- radiological indices- advanced indices

1. Atlanto-occipital movement

2. Warning sign of DELIKAN

3. Prayer sign

4. Palm Print test

5. Assessment of TMJ function

6. Assessment of mandibular space: thyrohyoid, thyromental, hyomental

7. Inter-incisor gap

8. Sternomental distance (SAVVA TEST)

9. Upper lip bite /catch test

10.Mallampati Score

11.Grading at direct laryngoscopy CORMACK - LEHANE

STERNOMENTAL DISTANCE (SAVVA TEST)STERNOMENTAL DISTANCE (SAVVA TEST)

• 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).

Predictors of difficult intubationIndividual indices

-Physical examination indices- radiological indices- advanced indices

1. Atlanto-occipital movement

2. Warning sign of DELIKAN

3. Prayer sign

4. Palm Print test

5. Assessment of TMJ function

6. Assessment of mandibular space: thyrohyoid, thyromental, hyomental

7. Inter-incisor gap

8. Sternomental distance (SAVVA TEST)

9. Upper lip bite /catch test

10.Mallampati Score

11.Grading at direct laryngoscopy CORMACK - LEHANE

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Class zero (0): The lower lip gliding over the upper lip positioning itself at any point above midway between the vermilion line and the columella: class I: The lower lip reaching a point midway between the vermilion and the columella; class II: The lower lip catches the upper lip at the level of the vermillion line or positioning itself just above it (2 mm); class III: The lower lip just caresses the upper lip, but falls short of obliterating the vermillion line

Significance:*Assessment of mandibular movement and dental architecture

**Less inter observer variability

Predictors of difficult intubationIndividual indices

-Physical examination indices- radiological indices- advanced indices

1. Atlanto-occipital movement

2. Warning sign of DELIKAN

3. Prayer sign

4. Palm Print test

5. Assessment of TMJ function

6. Assessment of mandibular space: thyrohyoid, thyromental, hyomental

7. Inter-incisor gap

8. Sternomental distance (SAVVA TEST)

9. Upper lip bite /catch test

10.Mallampati Score

11.Grading at direct laryngoscopy CORMACK - LEHANE

Test for assessing adequacy of the oropharynx for laryngoscopy and intubation

Mallampati grading (samsoon and young’s modification)

Mallampati Score 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 Class IV (difficult)—the soft palate is not visible at all(difficult)—the soft palate is not visible at all

Sensitivity: 44% - 81%Specificity: 60% - 80%

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

Predictors of difficult intubationIndividual indices

-Physical examination indices- radiological indices- advanced indices

1. Atlanto-occipital movement

2. Warning sign of DELIKAN

3. Prayer sign

4. Palm Print test

5. Assessment of TMJ function

6. Assessment of mandibular space: thyrohyoid, thyromental, hyomental

7. Inter-incisor gap

8. Sternomental distance (SAVVA TEST)

9. Upper lip bite /catch test

10.Mallampati Score

11.Grading at direct laryngoscopy CORMACK - LEHANE

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 = Grade I = success & ease of intubation success & ease of intubation

Predictors of difficult intubationIndividual indices

-Physical examination - radiological indices- advanced indices

1. Atlanto-occipital movement

2. Warning sign of DELIKAN

3. Prayer sign

4. Palm Print test

5. Assessment of TMJ function

6. Assessment of mandibular space: thyrohyoid, thyromental, hyomental

7. Inter-incisor gap

8. Sternomental distance (SAVVA TEST)

9. Upper lip bite /catch test

10.Mallampati Score

11.Grading at direct laryngoscopy CORMACK - LEHANE

indices-

Group indices

1. Wilson’s score

2. Saghei & safavi test

3. Lemon assesment

4. Upper and lower face

5. Arne’s simplified score Magboul’s 4M’s

6. 4 D’s

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Mobility of the head and neck (Angle formed between the positions of greatest extension and greatest

flexion of the neck)

Group indices

1. Wilson’s score

2. Saghei & safavi test

3. Lemon assesment

4. Upper and lower face

5. Arne’s simplified score Magboul’s 4M’s

6. 4 D’s

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

Group indices

1. Wilson’s score

2. Saghei & safavi test

3. Lemon assesment

4. Upper and lower face

5. Arne’s simplified score Magboul’s 4M’s

6. 4 D’s

• Look externally

• Evaluate internally

• Mallampati

• Obstruction

• Neck mobility

Difficult ETT Prediction

LEMON

Look Externally

• Beard

• Small jaw, receding chin

• “Buck” teeth

• Craniofacial deformity or trauma

Evaluate Internally

• 3-3-2

– 3 fingers of mouth opening

– 3 fingers mentum to hyoid

– 2 fingers hyoid to thyroid

Mallampati

Obstruction

• Pre-glottic obstructions

– Tongue enlargement

– Airway edema

Neck Mobility

• Ideally the neck should be able to extend back approximately 35°

• Problems:– Cervical Spine Immobilization– Ankylosing Spondylitis– Rheumatoid Arthritis– Fixation

Group indices

1. Wilson’s score

2. Saghei & safavi test

3. Lemon assesment

4. Upper and lower face

5. Arne’s simplified score Magboul’s 4M’s

6. 4 D’s

Upper & Lower Face

Measure 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

Group indices

1. Wilson’s score

2. Saghei & safavi test

3. Lemon assesment

4. Upper and lower face

5. Arne’s simplified score Magboul’s 4M’s

6. 4 D’s

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

1/ Previous knowledge of difficult intubation

No 0

Yes 10

2/ Pathologies associated with difficult intubation

No 0

Yes 5

3/ Clinical symptoms of airway pathology

No 0

Yes 3

4/ 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

5/ Thyromental distance simplified score

>6.5cm 0

< 6.5cm 4

6/ Maximum range of head & neck movement

Above 100° 0

About 90° (90° ± 10°) 2

Below 80° 5

7/ 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

Arne’s simplified score model

Magboul’s 4 M’s

Remember the 4(M & Ms) with (STOP) sign•Mallampati

•Measurement

•Movement

•Malformation 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) .

Group indices

1. Wilson’s score

2. Saghei & safavi test

3. Lemon assesment

4. Upper and lower face

5. Arne’s simplified score Magboul’s 4M’s

6. 4 D’s

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)

1. X-Ray neck (lateral view) :

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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 PREDICTORSRADIOGRAPHIC PREDICTORS

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 PredictorsADVANCED Predictors

•Flow volume loop

•Acoustic response measurement

•Ultra sound guided

•MRI

•Flexible bronchoscope

COPUR index assessing 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 4

COPUR index

• 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 (estimate range 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

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Structured Approach to Airway Management

ComponentComponent DescriptionDescription Assessment ActivitiesAssessment Activities

MMandibleandible Length and Length and subluxationsubluxation

Measure hyomental distance Measure hyomental distance and anterior displacement and anterior displacement of mandibleof mandible

OOpeningpening Base, symmetry, Base, symmetry, rangerange

Assess and measure mouth Assess and measure mouth opening in centimetresopening in centimetres

UUvulavula VisibilityVisibility Assess pharyngeal Assess pharyngeal structures and classifystructures and classify

TTeetheeth DentitionDentition Assess for presence of Assess for presence of loose teeth and dental loose teeth and dental appliancesappliances

HHeadead Flexion, extension, Flexion, extension, rotation of rotation of head/neck and head/neck and cervical spinecervical spine

Assess all ranges and Assess all ranges and movementmovement

SSilhouetilhouettete

Upper body Upper body abnormalities, both abnormalities, both anterior and anterior and posteriorposterior

Identify potential impact Identify potential impact on control of airway of on control of airway of large breasts, buffalo large breasts, buffalo hump, kyphosis, etc.hump, kyphosis, etc.

While this criteria helps identify difficult airways, it does not guarantee an easy intubation—

Be Prepared!

Nothing is more expensive than the missed opportunity