Airway Assessment

Dr. TUSHAR KUMAR,DA

Anaesthesiology and critical care

Airway

Anatomically, airway is the passage through which the air/gas passes during respiration.

It may be divided into:Upper airway, andLower airway

Upper airway

Upper airway comprises of the mouth/oral cavity, nasal cavity, pharynx, nasopharynx, oropharynx, and the larynx.

MOUTH/ORAL CAVITY: Extends from the mouth opening to anterior tonsillar pillars. Includes lips, cheeks, teeth n the tongue.

NASAL CAVITY: Extends from naris to the end of the turbinates.

Upper Airway

Upper Airway

Lower airway

Lower airway includes trachea, bronchi n 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.

Lower Airway

DEFINITION OF DIFFICULT AIRWAY(A.S.A. 1993)

A Difficult Airway is defined as the “clinical situation in which a conventionally trained anesthesiologist experiences difficulty with mask ventilation, difficulty with tracheal intubation or both”.

Airway Difficulties

Difficult to mask ventilate : 0.1 -5 % prevalence

Difficult laryngoscopy

Difficult to intubate: 1 – 2% normal surgical population. 50% of rheumatic cervical disease

Difficult LMA: 0.1 -5 % prevalence

Why airway assessment…..

Optimal patient preparation

Proper selection of equipment and technique, and

Participation of personnel experienced in the difficult airway management

How do you assess?

Difficult airway can be assessed by:

Individual indices

Group indices (with or without scoring)

Mask ventilation precedes laryngoscopy , which in turn followed by intubation.

So the assessment should be in following manner

What to assess ? ( components of the airway examination)I. Nostril patencyII. Length of upper incisor and alignmentIII. Condition of the teethIV. Relationship of upper incisor to the lower incisorV. Ability to protrude the lower incisor in front of the

upper incisor VI. Inter incisor distanceVII. Tungue sizeVIII. Visibilty of uvulaIX. Presence of heavy facial hairsX. Comliance of mandibular spaceXI. Thyromental distance with the head in maximum

extensionXII. Circumference of neckXIII. Range of motion of head and neck

EVALUATION OF THE AIRWAY

(A)   History

(B) General Examination

(C)   Specific Tests / indices

(D) Advanced indices

History

Patient/ notes/chart/ medic- alert

Any difficultySurgery / burnsConcurrent diseaseReflux / recent meals

II. General Examination

Starts with global assessment as soon as we see the patient.

Look for: 1. Dentition2. Distortion (edema, blood, vomits,

tumor, infection)3. Disproportion ( bull neck, large

tongue, small mouth)4. Dysmobility( TMJ and cervical spine)5. 0bese or pregnant

Speific tests / indices

A. Anatomical criteria

1. Relative to tongue/ pharyngeal size2. Atlanto occipital joint extension3. Mandibular space4. TMJ assessment

B. Direct Laryngoscopy

Anatomical criteria

Relative to tongue / pharyngeal size(mallampatti test)

Atlanto-occipital joint extensionDELLIKAN`S TESTPatient is asked to look straight ahead.

The index finger of the left hand of the clinician is placed under the tip of the jaw while the index finger of the right hand is placed on the patient's occipital tuberosity. The patient is now asked to look at the ceiling. If the left index finger becomes higher than the right, extension is considered normal.

WARNING SIGN OF DELIKAN

C. Assessment of the mandibular space

This space determines how easily the laryngeal n pharyngeal axes will fall in line when the A-o joint is extended and it also accommodates the tongue during laryngoscopy.

Assessment of the mandibular space

Thyromental distance(Patil’s test)Hyomental distanceSterno mental distance(savva test)

Thyromental Distance (Patil’s test)

Distance from the mentum to the thyroid notch.

Ideally done with the neck fully extended.

Helps determine how readily the laryngeal axis will fall in line with the pharyngeal axis.

Thyromental Distance (patil’s test)

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.

> 6.5 cm ; no problem with

laryngoscopy n intubation.

Hyomental distance

It is the distance between mentum and the hyoid bone.

It is graded as:Grade 1 - >6.0 cmGrade2 - 4 – 6 cmGrade3 - <4.0 cmGrade3 hyomental distance is

usually associated with difficult laryngoscopy and intubation.

Sternomental distance ( Savva Test)

This is measured with head in full extension and mouth closed.

<12.5 cm predicts difficult laryngoscopic intubation.

< 12.5 cm: limited neck movement

TMJ assessment

Inter incisor distanceMandibular protrusion testUpper lip bite / catch test

TMJ assessment

TMJ assessment

Upper lip bite / catch test

1. Class I: Lower incisor can bite upper lip above vermilion line

2. Class II: incisor can bite upper lip below vermilion line.

3. Class III: cannot bite upper lip.

2. Direct laryngoscopy

Cormack & Lehane grading

Grade 1: Full aperture visibleGrade 2: Lower part of cords visibleGrade 3: Only epiglottis visibleGrade 4: Epiglottis not visible

Laryngoscopic View Grades

Graded in order from the best view to worst.Grade 1: Visualization of the entire

laryngeal apeture

Laryngoscopic View Grades

Grade 2: Visualization of just the posterior portion of the laryngeal aperture . Anterior commissure not visulaized.

Laryngoscopic View Grades

Grade 3: Visualization of only the epiglottis

Laryngoscopic View Grades

Grade 4:

No glottic structure visible.

Individual indices 1) Presence of beard

2) Obesity

3)Abnormality of teeth : edentulous, irregular teeth or artificial teeth.

4) Elderly patients

5) Snorers

6) Jewellery and facial piercings

Difficult to mask ventilate: MOANS

Mask SealObesity or ObstructionAge > 55No TeethStiff

Mask Seal

Receding mandibleBurn stricturesBeardFacial Trauma

Obesity or Obstruction

Obesity

Heavy chest Abdominal contents

inhibit movement of the diaphragm

Increased supraglottic airway resistance

Difficult mask seal Quick desaturation

Age > 55 / No Teeth

Associated with difficult mask ventilation, possibly due to loss of tone in the upper airway. Face tends to “cave in”

Consider leaving dentures in for mask ventilation and remove for intubation

Stiff

Refers to Poor ComplianceReactive Airway DiseaseCOPDPulmonary Edema/Advance

PneumoniaHistory of Snoring/Sleep Apnea

GROUP INDICES

Wilson scoring systemBenumof’s analysisSaghei & safavi test

JUST A QUICK LOOK

Wilsons’ Rule for predicting difficult intubation :

5 factors into account

PARAMETER 0 1 2

WEIGHT < 90 Kg 90 – 110 Kg > 110 Kg

HEAD & NECK MOVEMENT

Above 90° About 90° Below 90°

JAW MOVEMENT IG > 5 cm (or) Slux > 0

IG = 5 cm& Slux = 0

IG < 5 cm& Slux < 0

RECEDING MANDIBLE

Normal Moderate Severe

BUCK TEETH Normal Moderate Severe

0 – Normal; 1 – Moderate; 2 – Severe patient scoring < 5-easy laryngoscopy

6-7 –moderate difficulty 8-10 –severe difficulty

BENUMOF’S 11 PARAMETER ANALYSIS

Parameter

Buck teeth Subluxation

Interincisor gap Palate configuration Mallampati class   Upper incisors length TM distance SMS compliance Neck thickness Length of neck Head /neck mvt

Minimum acceptable value

<1.5cm Yes >3cmNo arching/narrowness<2 <2 cm>5 cm Soft to palpation. Qualitative ( >33cm DI) >8cm Normal range

Saghei and safavi indices

Weight > 80 kgT0ngue protrusion >3.2cmMouth opening <5 cmUpper incisor length >1.5 cmMallampati class >1Head extension < 70 degree

Any 3 indices if present prolonged laryngoscopy

LEMON

L – Look externally ( facial trauma, large incisors, beard or moustache, large tongue )

E – Evaluate the 3-3-2 rule ▪ inter incisor distance – 3 finger breadths▪ hyoid- mental distance – 3 finger breadths▪ thyroid to floor of mouth distance – 2 finger breadths

M – Mallampati O – Obstruction

▪ epiglottitis, ▪ peritonsillar abscess▪ trauma

N – Neck mobility

Advanced Indices

1. Radiographic assessment

▪ From skeletal films▪ Flouroscopy▪ Oesophagogram▪ Ultrasonograpgy▪ Computed tomography / MRI▪ Video optical intubation stylets

2. Flow volume loop3. Acoustic response measurement4. Flexible bronchoscope

Investigations (cont):

Ultrasonography Assessment of

anterior mediastinum mass

X ray & CT Scan

Flexible bronchoscope

Others Palm Print & Prayer sign:

To Summarize

Airway assessment is a critical part of the airway management.

The airway assessment must always be performed prior to ALL RSI attempts.

While these criteria help identify difficult airway, it does not guarantee an easy intubation—Be Prepared!

Difficult Airways - Assess the Risks

Develop your skills and ways to assess the airway.

There are lot of scores and numbers , adapt what suits you…..What you can remember and apply.

“The difficult airway is something one anticipates; the failed airway is something one experiences.” -Walls 2002

Thank you