AIRWAY ASSESSMENT

&PREDICTORS OF

DIFFICULT AIRWAYBy

Dr Riyas A

INTRODUCTION Expertise in airway management is

essential in every medical speciality Maintaining a patent airway is essential

for adequate oxygenation and ventilation and 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 respirtory related injuries are inadequate ventilation,oesophageal

intubation,difficult tracheal intubation

DIFFICULT AIRWAYIt’s is one in which there is a problem in

establishing or maintaining a gas exchange via a mask ,an artificial airway or both

Recognising these difficulties before anaesthesia allows time for optimal preparation ,proper selection of equipments and tehniques and participation of perssonal who is experienced in DA management

ASSESSMENT History Medical ,surgical or anaesthetic factor

may be indicative of a difficult airway Some factors which could prdispose to

difficult airway are 1)burns 2)oedema 3)bleeding 4)tracheal stenosis 5)perforation,etc….

SOME AIRWAY COMPROMISING CONDITIONScongenital 1)Pierre robbing

syndrome2)Goldenhar’s syndrome3)Treacher collins syndrome4)Downs5)Goiter6)Kippel fiel syndrome

CONTINUATION… Acquired Infection 1)Croup

2)Supraglottic3)Intra oral and retropharyngeal abscess4)Ludwigs angina

Arthirtis Ankylosing spondylitis

GENERAL PHYSICAL AND REGIONAL EXAMINATION Patency of nares Mouth opening of at least 2 large finger

breadths between upper and lower incisors

Teeth: Palate:high arched plate ,enlarged

tonsilnarrow mouth Assesses patients ability to protrude the

lower jaw beyond the upper incisors Temporo mandibular joint movement

GPE AND RE CONTINUATION…. Measurement of submental

space(hyomental/thyromental length should be >6)

Observation of patient neck Presence of hoarse voice /stridor or any

history of tracheostomy suggest stenosis

Any systemic or congenital disease requiring special attention during air way management(respiratory ,significant coronary artery disease,acromegaly)

GPE AND RE CONTINUATION… General assessment of body habitus can

yield important information Infections of airway Physiological conditions

CONDITIONS TO BE LOOKED FOR DIFFICULT MASK VENTILATION… Presence of beard Body mass index Lack of teeth Age and snoring Jewellery worn by piercing the

lips ,tongue,cheek ,chin eye brows and ear may also create difficulty in mask ventilation…

SPECIFIC TESTS FOR ASSESSMENT A ) Anatomical criteria 1]tongue and phayngeal size

relation….. a) Mallampatti score….head in neutral

position , patient sitting , mouth wide open ,tongue protruding maximum,patient shouldn’t be actively encouraged to phonate as it can result in contraction and elevation of soft palate leading to false positive result

MALLAMPATTI SCORE Class 1:Visualisation of anterior and

posterior pillars,soft palate,uvula,hard palate

Class 2:visualisation of uvula,soft palate and hard palate

Class 3:visualisation of softpalate and base of uvula

Class 4:(samsoon n young modified mallampatti and added this)only hard palate is visible

To avoid false positive and negative results this shoulb be repeated twice

ANATOMICAL CRITRIA CONTINUATION… Atlanto occipital joint extension:it assess

fesibility to make sniffing or magills position for intubation;ie,alignment of oral,pharyngeal and laryngeal axis into an arbitary straight line.

Patient is asked to hold head in erect position ,facing directly to front ,then he is asked to extend his head maximally and examiner estimates the angle transversed by occlusional surface of upper teeth

CONTINUATION….AO EXTENSION It’s expressed in grades …1. grade 1:>352. grade 2: 22-343. grade 3: 12-214. grade 4: <12

o Noraml angle of extension is 35 or more

MANDIBULAR SPACEA. Thyro mental distance(pail’s test):it’s defined

as the distance from the mentum to the thyroid notch while the patient neck is fully extended,

this measurement helps in determining how readily the laryngeal axis will fall in line with the pharyngeal axis when AO joint is fully extended

alignment of these two axis is difficult if the distance is <3 finger breadth or <6 cm in adults

6-6.5 cm less difficulty ,while more than 6.5 is normal

PATILS TEST

MANDIBULAR SPACE CONTINUATION…B ) Sterno mental distance:it’s measured

from suprasternal notch to the mentum It was mesured with head fully extended

on the neck with the mouth closed Value <12 cm found to predict the difficult

intubationC )mandibulo hyoid distance:Measurement

of chin to hyoid should be atleast 4cm or three finger breadths

D ) Inter incisor distancedistance b/w upper and lower incisors normal is 4.6cm while <3.8 predicts difficult airway

WILSON AND COLLEAGUES SORING SYSTEMThey took 5 variables1. Weight 2. Head ,neck and jaw movements3. Mandibular recession presence or absence

of buck teeth Risk score was developed b/w 0-10Arne and collegues introduced a new soring

systemWILSON AND COLLEGUE SCORING SysteM

+presence or absence of overt airway pathology

LEMON AIRWAY ASSESSMENTL= look externally E= evaluate 3-3-2 rule(inter incisor

distance,hyoid mental distance,thyroid mental distance)

M= mallampattiO= obstructionN= neck mobility

LEMON AIRWAY ASSESMENT

SPECIFIC TEST B )direct laryngo scopy and fibro optic

broncho scopyI. Grade 1-visualisation of entire

laryngeal apertureII. Grade 2-visualisation of only posterior

commisureIII. Grade 3-visualistion of only epiglottisIV. Grade 4-just soft palateGrade 3 & 4 predict difficult intubation

SPECIFIC TESTC ) Radio graphic assesssment

From skeletal films…lateral cervical x ray film of the patient with the head in neutral position is recquired for the following measurments

i. Mandibulo hyoid distanceii. Atlanto occipital gap:A-O gap is the major factor

which limits the extension of head and neckiii. Relation of mandibular angle and hyoid bone

with cervical vertebrae and laryngoscopy grading:a definite increase in difficulty in laryngoscopy was observed when the mandibular angle tended to be more rostral and hyoid bone to be more caudal

SPECIFIC TEST …RADIOGRAPHIC ASSESSMENT CONTI

4)Anterior posterior depth of the mandible: the distance b/w the boney alveolus

immediately behind the 3rd molar tooth and the lower border of the mandible is an important masure in determining the laryngoscopy

5)C1-C2 gap Calcified stylohyiod ligaments are manifested by

crease over hyoid bones on radiographic examination

Laryngoscopy is difficult because of inability to lift the epiglottis from the posterior pharyngeal wall

SPECIFIC TEST CONTINUATION Fluroscopy Oesophagogram Ultrasonography CT / MRI Video optical intubation stylets

SPECIFIC TEST Preditors of difficult airway in diabetics1. Palm print:the patient is made to

sit ;palm and fingers of the right hand are painted with blue ink,patient then pressess the hand firmly against a white paper placed on hard surface

Grade 0-all the phalangeal areas are visible

Grade 1-deficiency in the interphalyngeal areas of the 4th and 5th digits

PALM PRINT GRADING…Grade 2-deficiency in interphalyngeal

areas of 2nd -5th digitsGrade 3-only tips of the digits are seen

DIFFICULT AIR WAY IN DIABETIC Prayer sign…patient is asked to bring

both the palms together as namaste and categorized as

positive …when there is gap b/w palms negative… when there is no gap

INDICATORS OF DIFFICULT INTUBATIONa) Poor flexion extension mobility of the

head on neckb) A receding mandible and presence of

prominent teethc) A reduced A-O distance, reduced space

b/w C1 and occiputd) Large tongue size

SIX STANDARDS IN EVALUATION OF AIRWAY Tempero mandibular mobility(one

finger) Inspection of muth ,oropharynx—

mallampatti classipfication(two finger) Measurement of mento-hyoid distance

in adults(three finger) Measurement of distance from chin to

thyroid notch(four fingers) Ability to flex head towards

chest,extend gead at atlanto occipital junction and rotate head ,turn right and left(five movements)

Symmetry and patency of nose

QUICK AIRWAY ASSESSMENT TM joint movement Neck movement Jaw movement mallampatti

ASSESSMENT OF PEDIATRIC AIRWAY Same like adults begins with history and

physical examination History regarding complaints of

snoring,day time somnolence,apnea,hoarse voice,prior surgery or radiation treatment to face or neck

Any anesthetic previous history of oropharyngeal injury,awake intubation,damage to teeth,or postponement of surgery following anaestheisa

ASSESSMENT OF PAEDIATRIC AIRWAY Physical examination:it should focus on

the anomalies of face ,head ,neck and spine

Evaluate size and shape of head ,gross features of the face,size and symmetry of the mandible,presence of sub mandibular pathology,size of tongue,shape of palate

Presence of retraction of intercostal muscles

Breath sounds Trancutaneous co2 determinants are

very helpful in infants and young childrens

TEST IN CHILDRENS TO PREDICT DIFFICULT AIRWAY Plain radiography CT and MRI Direct or Indirect laryngoscopy Fluroscopy USG studies Pulmonary function studies

CONCLUSION No single airway test can provide a high

index of sensitivity and specificity for prediction of difficult airway

However in some patients difficult airway will remain undetectable

Anaesthetologist be always prepared with a variety of plans for an unanticipated difficulty airway

THANK YOU