Airway anatomy-Its Assessment and Anaesthetic Implication

Presented ByDr Aparna Sahu1st Yr PG Dept. Of AnaesthesiologyVIMSAR Burla

ANAESTHESIOLOGIST – CRUCIAL ROLE IN AIRWAY MANAGEMENT

ANATOMY OF AIRWAY

PHYSIOLOGY OF AIRWAY

SKILLS

AIRWAY ASSESSMENT

SAFE AND SMOOTH CONDUIT OF ANAESTHESIA

DEFINATION

Airway is defined as a passage through

which the air/ gas passes during respiration

OR

In practise of airway management it is described as any artificial device with a lumen to aid ventilation &/or serve as a conduit to endotracheal intubation.These include intubating laryngeal mask airway (LMA), oropharyngeal airway, nasopharyngeal airway or several varieties of laryngeal mask airway

ASA DEFINITION1)DIFFICULT AIRWAY –It is defined as “ the clinical situation in which a conventionally

trained anaesthesiologist experiences difficulty with mask ventilation, difficulty with tracheal intubation or both .”

2)DIFFICULT MASK VENTILATION-”The inability of a trained anesthesiologist 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.

3)DIFFICULT LARYNGOSCOPY-”It is not possible to visualize any portion of vocal cord with conventional laryngoscope. Corresponds to cormack & lehane’s grade IV laryngoscopic view

4)DIFFICULT ENDOTRACHEAL INTUBATION-When proper insertion of Tracheal tube with conventional laryngoscopy requires

More than 3 attempts Longer than 10 minutes Failure of optimal best attempt

5)OPTIMAL /BEST ATTEMPT AT LARYNGOSCOPY Can be defined as ‘laryngoscopy performed by a reasonably experienced laryngoscopist with the patient in optimal sniff position having no significant muscle tone & the laryngoscopist has an option of change of blade type & length(one time each)

6)INTUBATION ATTEMPT-Defined as “Intubation activities occuring during a single continuous laryngoscopy manuever

ASA DEFINITION

CLASSIFICATION OF AIRWAY 1)UPPER AIRWAY-

– Mouth,oral cavity,oropharynx,– Nostrils, nose ,nasal

cavity,nasopharynx,pharynx, larynx

MOST VULNERABLE AREA FOR OBSTRUCTION2)LOWER AIRWAY –

– Trachea,bronchi, bronchioles,alveoli

SIGNIFICANCE-– Upper airway serves to

warm,filter,humidify the air/gas before it enters the lower airway .Bypassing these structures during ETT Intubation,makes it essential to provide warm humidified air/gas while patient breath spontaneously

– Lower airway serves in exchange of gases

ORAL CAVITY• EXTENSION LIPS TO OROPHARYNGEAL ISTHMUS

I.E. UPTO LEVEL OF ANTERIOR PILLARS OF TONSIL

• BOUNDARIES - ROOF Hard and soft palates.

FLOOR Soft tissues, which include a muscular diaphragm and the tongue.

LATERAL WALLS Cheeks

POSTERIOR aperture of the oral cavity is the oropharyngeal isthmus

FUNCTION– 1) Inlet for the digestive system – 2) Manipulates sounds produced by the larynx and

one outcome of this is speech – 3) Can be used for breathing because it opens into

the pharynx, which is A common pathway for food and air.

– 4)Due to relatively small size of nasal passage and significant risk of trauma mouth is often used as conduit for airway devices

MUSCLES OF TONGUE

SIGNIFICANCE • JAW THRUST MANUEVER This manuever uses the sliding component of

temporomandibular joint to move the mandible and attached tongue anteriorly relieving airway obstruction caused by posterior displacement of tongue into oropharynx (During sleep, decreased consciousness, during general anaesthesia)

• Caution should be maintained during laryngoscopy as lips can be injured

• Loose/bucked tooth can lead to difficult intubation

• Depletion of buccal fat ( old age ) – Difficult mask ventilation

NOSE AND NASAL CAVITY• Airway functionally begins at nostril, the external

opening of nasal passage

• Only externally visible part of the respiratory system

• Nose is divided into two regions– External nose– Internal nasal cavity

• EXTERNALLY ALAE NASI• Lateral margins of the nostrils• Flaring of ala nasi Airway obstruction• Infolded while introducing any tube via the nostril• Distance from alae nasi to various points on external

ear(tragus,meatus)

Estimate the length of airway device

NASAL CAVITY

• Extends from external nares to the post. nasal aperture

• Divided by nasal septum into rt. & lt. Halves• Each half has a roof, floor, lateral wall &

medial wall

NASAL CAVITY

ROOF – Cribriform plate of ethmoid bone Fracture leading to CSF rhinorrhea, is a contraindication for passing nasogastric tube or nasotracheal tubePositive pressure mask ventilation is also a contraindication as it may leads to entry of infection

FLOORPalatine process of maxilla in its anterior 3/4th and horizontal part of palatine bone in posterior 1/4th

Almost perpendicular to the plane of the faceSo the tube should be inserted perpendicular to the plane of face

LATERAL WALL3 bony turbinates or conchae , 3 meatusEasily damaged by force during passage of nasotracheal tubeParanasal sinuses opening & its drainage may be impaired by prolonged nasotracheal intubation.

INFERIOR MEATUS IS THE PREFERRED PATHWAY FOR PASSAGE OF NASAL AIRWAY

DEVICES.IMPROPER PLACEMENT IN NOSE CAN RESULT IN AVULSION OF A TURBINATE

NASAL SEPTUM Principal constituents are-

• Perpendicular plate of ethmoid & vomer

• Septal cartilage

- NASAL SEPTUM DEVIATION is common in adults therefore the more patent side should be determined before passing instrumentation through nasal passage

- Has highly vascular area (LITTLE’S AREA) in anterior 1/3rd of

nasal cavity. Vasoconstrictor should be applied

usually topically before instrumentation to avoid epistaxis

MEDIAL WALL-

FUNCTION OF NOSE• Inspired air is: – Humidified by the high water content in the nasal cavity– Warmed by rich plexuses of capillaries

• Ciliated mucosal cells remove contaminated mucus • Turbinates increase mucosal area(166cm2) for

humidification & enhance air turbulence & help filter air

• During exhalation these structures:– Reclaim heat and moisture– Minimize heat and moisture loss

Significance • In endotracheal intubation, nose is bypassed so to maintain the humidity of inspired air,

humidifiers should be used.

• At 37°c & 100% realtive humidity absolute humidity is 44mg/ml, At room temperature i.e. 21°c & 100% humidity) it is 18mg/l . Normal inhaled gases at OT room are administered at room temperature with little/ no

humidification.So gases should be warmed to body temperature and saturated with water vapour

• Tracheal intubation & high fresh gas flow bypasses this humidification system exposing lower airway to dry(<10cm h2o/l)room temperature gases

• Prolonged exposure of lower reapiratory tract to this non – humidified air leads to :– 1) dehydration of mucus– 2)altered ciliary function– 3)inspissation of secretion– 4)atelectasis– 5)ventilation-perfusion mismatch

PARTICULARLY I NUNDERLYING LUNG

DISEASE

PHARYNX• Extends from base of skull to cricoid cartilage

anteriorly and to inferior border of sixth cervical border posteriorly

• 12-14 cm long• 3.5cm wide at its base • 1.5cm at pharyngoesophageal junction(narrowest

part of digestive system• Posterior pharyngeal wall made up of

buccophayngeal fascia which separates pharngeal structures from retropharyngeal space.Improper placement of gastric or tracheal tube can result in laceration of fascia

Pharynx is further subdivided into :

• Nasopharynx

• Oropharynx

• Laryngopharynx or hypopharynx.

NASOPHARYNX• Extends from posterior nasal aperature to the

posterior pharyngeal wall above the soft palate.

• Ends at soft palate , this area is called velopharynx & is common site for airway obstruction in both awake and anaesthesised patient

• Roof of nasopharynx forms an acute angle with the posterior pharyngeal wall – while passing any tube through the nose into the oropharynx a simple maneuver of extension of head will straighten out this angle & facilitates the passage of tube

• Adenoids are located in its roof – which are frequently hypertrophied during childhood & may cause obstruction or hemorrhage while passing any tube through the nose.

• Retropharyngeal & peritonsillar abscess possess anaesthetic challenges

OROPHARYNX

• EXTENSION Soft palate to epiglottis Includes tonsil, uvula & epiglottis.

• Most important area in terms of airway obstruction & management as it is made of collapsible soft tissue all around.

• Previously it has been thought that upper airway obstruction occur due to tongue fall but now it shows that airway obstruction occur mostly at the level of soft palate & epiglottis.

• Jaw thrust & neck extension will helps to create space between the epiglottis & posterior pharyngeal wall.

• VALLECULA - The entire space between epiglottis & base of tongue

& has paired depression of the two sides of median glossoepiglottic fold. Laryngoscope blade tip lies in vallecula during classical macintosh laryngoscopy

LARYNGOPHARYNX OR HYPOPHARYNX

• It extends from epiglottis to the beginning of oesophagus.

• On each side of the laryngeal

inlet, the lateral wall of laryngo-pharynx presents the piriform fossa which is a deep depression.It acts as a catch point for foreign body.

LARYNX

SITUATION & EXTENT• It lies in the midline of neck opposite C3 to C6

vertebra in adult & C1 to C4 vertebra in children. It extends from the upper border of epiglottis to lower border of cricoid cartilage.

MEASUREMENT MALE FEMALE• Vertical Length - 44mm 36mm• Transverse diameter - 43mm 41mm• A-P diameter - 36mm 26mm

SKELETON OF LARYNX

• Composed of hyoid bone & a series of cartilage & are moved by a number of muscle. The cavity of larynx is lined by mucous membrane. Larynx contains 9 cartilages

• 3 Unpaired -Thyroid -Cricoid -Epiglottis

3 Paired - Arytenoid - Corniculate - Cuneiform

THYROID CARTILAGE

Largest of laryngeal cartilage Consist of 2 quadrilateral laminae, fuse along their inferior

two third anteriorly to form laryngeal prominence

" B U R P “ T E C H N I Q U E - (Backwards Upwards Rightwards Pressure) manoeuvre,

which is used to improve the view of the glottis during laryngoscopy and tracheal intubation . It requires a clinician to apply pressure on the thyroid cartilage posteriorly, then cephalad (upwards) and, finally, laterally towards the patient's right.

CRICOID CARTILAGE

• It represent the anatomical lower limit of Larynx & is the only complete cartilaginous ring in the airway.

• It is the narrowest part of upper airway in children, so uncuffed ETT are used in children.

• Cricoid doesn’t allow space for edema to spread outwards & thus any injury in this area can worsen quickly.

S E L L I C K ’ S M A N EAU V E R – In patients who are at risk of gastric aspiration, during airway management downward pressure over cricoid cartilage will prevent passive regurgitation without subsequent airway obstruction. This is known as Sellick’s Maneuver

EPIGLOTTIS• Thin leaf like plate of elastic fibrocartilage projects obliquely

upward behind the tongue and hyoid body and in front of

laryngeal inlet

Free end Attached part Broad and

notched in

midline

Long and narrow Connected to

elastic thyroepiglottic ligament

Sides: Attached to arytenoids by aryepiglottic folds

Function of epiglottisDuring Deglutition

closure of the laryngeal inlet during deglutition takes place by the

apposition of the aryepiglottic folds due to contraction of aryepiglotticus musle.the epiglottis does not fall back to close the inlet like a lid, instead it moves upward and comes in contact with the dorsal surface of the posterior third of tongue.

Assist in phonation

Prevent aspiration of food into the trachea

MUSCLE OF THE LARYNX • EXTRINSIC MUSCLE – which attaches larynx to the surrounding structures• INTRINSIC MUSCLE - which attaches laryngeal cartilages to each other.

EXTRINSIC MUSCLE SUPRAHYOID MUSCLE – Attaches larynx to the hyoid bones & elevate the larynx eg. – Geniohyoid, Stylohyoid, Mylohyoid, Diagastric, Thyrohyoid, Stylopharyngeus. INFRAHYOID MUSCLE – Strap muscle, in addition to lowering of larynx, can modify the internal relationship of laryngeal cartilage & folds to one another. eg. – Sternohyoid, Sternothyroid, Omohyoid, Thyrohyoid.

• INTRINSIC MUSCLE • I – ACTING ON VOCAL CORD

Abductor – Posterior crico arytenoid Adductor – Lateral crico arytenoid Transverse & oblique

arytenoid Tensor (Elongation) – Cricothyroid Partly Vocalis Relaxor (Shortening) – Thyro arytenoid Partly Vocalis

• II – ACTING ON LARYNGEAL INLET Openers - Thyro epiglotticus Thyro arytenoid Closer – Ary epiglotticus Oblique arytenoid

Laryngeal cavity • Extends from laryngeal inlet down

to lower border of cricoid cartilage where it continues into trachea

• By paired upper and lower mucosal fold projecting into lumen laryngeal cavity is divided into-

UPPER(SUPRAGLOTTIC) MIDDLE(SINUS)

LOWER(INFRAGLOTTIC) Upper fold : Vestibular fold(FALSE

VOCAL CORD) guarding rima vestibuli.

Lower fold :Vocal fold(TRUE VOCAL CORD)guarding rima glottidis

UPPER FOLD – Vestibular fold (False Vocal Cord) Pink in colour

LOWER FOLD – Vocal fold (True Vocal Cord) Pearly white in colour Vocal fold is attached to the middle of thyroid angle anteriorly & to the vocal process

of arytenoid cartilage posteriorly.

The space between the right & left vestibular fold – RIMA VESTIBULI.It permits air entry in inspiration and prevents air exit in expiration.so it acts as an exit valve.Essential to increase intra-abdominal pressure by holding of breath at end of inspiration during act of micturation,defecation,coughing or parturition in female.

The space between the right & left vocal fold – RIMA GLOTTIDIS OR GLOTTIS.It permits air exit in expiration and prevents air entry in inspiration.so acts as entry valve.

GLOTTIS

It is the narrowest part of the larynx in adult.

A-P length Male – 24 mm Female – 16 mmIt is divided into two part – I – Anterior inter-membranous

part (3/5) – Situated between the two vocal fold.

II- Posterior inter- cartilaginous part (2/5) – Passes between the two arytenoids cartilage.

NERVE SUPPLY OF LARYNX SENSORY – Above the vocal cord

– Superior laryngeal nerve Below the vocal cord -

Recurrent laryngeal nerve MOTOR – All intrinsic muscle of

the larynx are supplied by RLN except cricothyroid which is supplied by external laryngeal nerve which is a branch of SLN.

SECRETO MOTOR - RLN Both SLN & RLN are branches

of vagus nerve

ARTERIAL SUPPLY & VENOUS DRAINAGEABOVE THE VC - Superior laryngeal artery, a

branch of superior thyroid artery. Superior laryngeal vein,

drains into superior thyroid veinBELOW THE VC – Inferior laryngeal artery, a

branh of inferior thyroid artery. Inferior laryngeal vein, drains

into Inferoir thyroid vein. LYMPHATIC DRAINAGEABOVE THE VC - Pre laryngeal & Jugulo –

Digastric LN. BELOW THE VC – Pre tracheal & Para tracheal

LN.

COMPARISION BETWEEN PEDIATRIC & ADULT AIRWAY

5 DIFFERENCES -1– Relatively larger tongue – Obligate nasal breather. 2 – Large & omega-shaped epiglottis 3 – More rostral larynx 4 - Funnel shaped larynx - Narrowest part of pediatric airway is cricoid

cartilage. 5 – Angled vocal cord – Infant VC have more angled attachment to

thyroid angle whereas adult VC are more perpendicular.

LARYNGEAL FUNCTION

• AIRWAY PROTECTION• PHONATION-The vocal cords: Adducted for

phonation; abducted for inspiration

Laryngoscopic anatomy • To view larynx

– Mouth, oropharynx and larynx must be in one

plane

CRICOTHYROTOMY• ‘Surgical’ airway via the cricothyroid membrane in acute

emergency when obsruction at or above the larynx not relieved.

• Patient positon: supine and the neck in the neutral position or (in the absence of cervical spine injury) in extension

Airway Assessment

Why it is necessary ??

• PURPOSE - TO DIAGNOSE THE POTENTIAL FOR DIFFICULT AIRWAY FOR– -Optimal patient preparation– -Proper selection of equipment – -Participation of personnel experienced in difficult

airway management

Causes of difficult airway

1)FACIAL ANOMALIES- Maxillary hypoplasia,mandibular hypoplasia & HYPERPLASIA2)TMJ PATHOLOGY- Ankylosis or reduced movement3)MOUTH & TONGUE - Microstomia(burns,trauma), tongue,tumor of ANOMALY mouth & tongue ,macroglossia(down’s syndrome,hypothyroidism)4)TEETH PROBLEMS - (Missing left upper incisors,protruding upper incisors)5)NOSE PATHOLOGY- Hypertrophied turbinate,polyps,gliomas,foreign bodies6)PALATE PATHOLOGY- Narrow arched palate,large cleft palate7)PHARYNX PATHOLOGY- Hypertrophied tonsils & adenoid,tumors, abscess, retropharyngeal /parapharyngeal abscess8)LARYNX PATHOLOGY- Epiglotitis, laryngomalacia, foreign body, papillomas, congenital stenosis ,edema 9)TRACHEAL PATHOLOGY- Tracheitis, tracheoesophageal fistula, tracheal stenosis & webbing, foreign body, tracheomalacia10)BROCHIAL TREE - Mediastinal mass, foreign body aspiration, PATHOLOGY bronchial tumors11) NECK – Large goitre, skin contracture, ankylosing spondylitis12)SPINE- Limitation of movement( congenital klippel-feil syndrome, Acquired- surgical fusion,fracture of cervical vertebrae) ; cervical spine instability (down’s syndrome)

Airway assessment• History

– Patient/notes/chart/previous anaesthesia records– Surgery/burns/trauma/tumor in & around oral cavity– Concurrent disease– Reflux/recent meals

• General examination– Do they just look difficult?– Recognition of anatomic factors that can cause difficult airway

• Specific tests/indices• Investigations.

– Nasoendoscopy– X-ray, CT/MRI– Flow volume loop

How do you assess ??

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.

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)• Patient having ≥2 of the

predictors likely to have difficult mask ventilation

(MOANS)• MOANSThis 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

Predictors of difficulty to face mask ventilate

Individual indices -Physical examination indices -radiological indices -advanced indicesGroup indices - Wilson’s score - Benumof’s 11 parameter analysis - Saghei & safavi test - Lemon assesment - Arne’s simplified score - Magboul’s 4 M’s

ASSESSMENT OF CERVICAL & ATLANTO-OCCIPITAL JOINT

• DIRECT ASSESSMENT – Assess the neck movement by asking the patient to touch his manubrium sternii with his chin. If done this assures neck flexion of 25-30°.

• Then ask the patient to look at ceiling without raising eyebows to test a-o joint extension

• GRADE 3 & 4 INDICATE DIFFICULT LARYNGOSCOPY

Grade Reduction of A.O.Extension

1 none2 1/3RD REDUCTION3 2/3RD REDUCTION4 COMPLETE

REDUCTION

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

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.

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 5thdigit.

* Grade2 - Deficiency in the inter-phalangeal areas of

2nd to 5th digit.

* Grade 3 - Only the tips of digits seen. - Predictor of

Difficult Airway in DM

ASSESSMENT OF TMJ FUNCTIONTM 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.

SUBLUXATION OF THE MANDIBLE 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

indented in its space and the thumb can feel the sliding movement of the condyle as the condyle of the mandible slides forward.

CALDER TEST

Assessment of mandibular spaceThis space determines how easily the laryngeal and pharyngeal axis will fall in line when the a-o joint is extended.

Thyromental Distance/PATIL’S TEST Measure from upper edge of thyroid cartilage

to chin with the head fully extended

HYO MENTAL DISTANCE

>6.5CM

NO PROBLEM WITH LARYNGOSCOPY & INTUBATION

6-6.5CM

DIFFICULT LARYNGOSCOPY & INTUBATION

<6 CM

LARYNGOSCOPY MAY BE IMPOSSIBLE

Distance between mentum and hyoid bone

Grade I : > 6cmGrade II: 4 – 6cmGrade III : < 4cm – Impossible laryngoscopy & Intubation

LimitationsLittle reliability in predictionVariation according to height, ethnicityModification to improve the accuracyRatio of height to thyromental distance (RHTMD)Useful bedside screening testRHTMD > 23.5 – very sensitive predictor of difficult laryngoscopy

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

STERNOMENTAL DISTANCE (SAVVA TEST)

• 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).

UPPER LIP BITE /CATCH TESTClass 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 lipSignificance• Assessment of mandibular movement and dental architecture• Less inter observer variability

Test for assessing adequacy of the oropharynx for laryngoscopy and intubation

• Mallampati grading (samsoon and young’s modification)

• Narrowness of the palate- EVALUATED WHILE PERFORMING MALLAMPATI GRADING. A NARROW , HIGH ARCHED PALATE MAY HAVE DIFFICULT LARYNGOSCOPY & INTUBATION

M A L L A M P AT T I G R A D I N G

• Suggest optimal tongue size in relation to oropharyngeal cavity permitting easy laryngoscopy.

• Indicate amount of space within the oral cavity to accommodate the laryngoscope & ETT

• Assessed when the patient is -seated -upright with head neutral -the mouth open -tongue protruded as much as possible - no phonation. The observer’s eye At the level of

patient’s open mouth

• Higher scores poor visibility of the oropharyngeal structures Large tongue relative to the size of the oropharyngeal space Difficult laryngoscopy

Assessment for quality of glottic viewing during laryngoscopy

Indirect mirror laryngoscopic view-closely relates with cormack & lehane grading

Direct laryngoscopy ‘awake look’ -cormack and lehane gradingGrading ease of intubationPOGO (percentage of glottic opening) scoring

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

Grading ease of intubation

Grade 1 Extrinsic manipulation of larynx not required

Grade 2 Extrinsic manipulation of larynx required

Grade 3 Intubation possible with stylet guided

Grade 4 Failed intubation

POGO SCORING

• Percentage of glottic opening during direct laryngoscopy

• 100%- entire glottic structures visible

• 33%-only lower third of vocal cord & arytenoid visible

• 0%-no glottic structure visible

• USEFUL WHEN NEW INTUBATING DEVICE TO RECORD EXACT % OF GLOTTIC OPENING THAT CAN BE VISUALISED BY THIS DEVICE

Group indices

- Wilson’s score - Benumof’s 11 parameter analysis - Saghei & safavi test - Lemon assesment - Arne’s simplified score - Magboul’s 4 M’s - 4 D’S

Wilson’s risk scoreScore

Weight 0=<90kg1=90-110kg2=>110kg

Head and neck movement 0=Above 90degrees1=About 90degrees2=Below 90degrees

Jaw movement 0=IG>5cm or SLux >01=IG=5cm and SLux = 02=IG<5cm and SLux<0

Receding mandible 0=Normal1=Moderate2=Severe

Buck teeth 0=Normal1=Moderate2=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 =easy laryngoscopy•Score 6-7=moderate difficulty•Score 8-10 =severe difficulty in laryngoscopy

BENUMOF’S 11 PARAMETER ANALYSISParameters Minimum acceptable value

1. Bucked tooth No overriding2.Inter–incisor gap >3cm3.Length of upper incisors <1.5cm4.Mandible protrusion test Mandibular teeth can be

protruded beyond maxillary teeth

5.Mallampati class < Class 26.Palate configuration No arching or narrowness7.Thyromental distance >5cm/>3 finger breadth8.Mandibular space compliance

Soft to palpation

9.Neck length Qualitative 10.Neck thickness Qualitative11. Head /neck mvt Normal range

4-2-2-3 rule 4 for tooth

2 for inside of mouth

2 for mandibular space

3 for neck examination

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

Arne’s simplified score model

• 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

• 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...... 48Score of >11 is predictive of difficult tracheal intubation

LEMON trialREPRESENTS 5 SIMPLE RAPID ASSESSMENT METHODS ON

UNCOPERATIVE & COPERATIVE PATIENTLook

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)

MallampatiObstruction• Neck mobility – chin to chest

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

EVALUATE 3-3-2• Mouth Opens at least 3

finger widths.

• Three finger widths thyromental distance.

• Two finger widths hyomental distance.

Obstruction• Laryngoscopy or intubation

may be more difficult in the presence of an obstruction

– LOCATION – FIXITY – PROGRESSION

Neck Mobility• NORMAL• NECK EXTENSION >80-85 , • FLEXION > 25- 30• ROTATION > 70-75• ASSESS ALL 3 ANGLES

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) .

• PATIENT SCORE >= 8 DIFFICULT INTUBATION

4 DsThe 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)

RADIOGRAPHIC PREDICTORS 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.

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

Points of measurements from skeletal films ; 1 = Effectivemandibular length, 2 = Posterior mandibular depth, 3 = Anterior mandibulardepth, 4 = Atlanto-occipital gap, 5 = C1 – C2 gap

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

How to predict difficulty in creating surgical airway (BANG)

• Bleeding tendency• Agitated patient• Neck scarring• Growth or vascular

abnormality in region of surgical airway.

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!

THANK YOU