PRINCIPLES OF AIRWAY ASSESSMENT Moderator : Dr. Anil Ohri Presented by : Dr. Arun Kumar Sharma

Airway: Extra pulmonary passage. Difficult airway: Problem in establishing or maintaining gas exchange via a mask , artificial airway or both. Difficult airway is single most important cause of anesthesia related morbidity and mortality. Upto 30% deaths attributable to anesthesia are due to inadequate airway management. Difficult airway clinics: allows time for optimal preperation , proper selection of equipment and technique and personal experienced in difficult airway management.

Objectives History General, physical and regional examination Specific tests for assessment *Mallampati test *Atlanto occipital joint (AO) extension *Mandibular spaces *Wilson’s clasification *Ame &co. *LEMON Score *Radiological assessment

ASSESSMENT History and physical examination: History : Medial , surgical and anesthetic factors. Anesthetic factors: edema , burns , bleed, tracheal compression , pneumothorax or aspiration of gastric contents.

Physical Examination Patency of nares: Mass,DNS, etc Mouth opening : atleast 3 fingers btw upper and lower incisors. Teeth : prominent upper incisors. Palate : high arched palate or long narrow mouth. Tongue size Patients ability to protrude lower jaw. Mandible TMJ movement Submental space Observation of patients neck-mass ,mobility , and ability to assume sniff position. Hoarse voice/stridor or h/o tracheostomy: stenosis Airway infections Physiological conditions : pregnancy and obesity.

Difficult to mask ventilate Factors affecting- Presence of beard Disfiguring malignancy of jaw BMI >26 Absence of teeth Age >55 H/o snoring Obstuctive sleep apnoea Mallampati class 3&4

Specific Tests

Based on tongue/ pharyngeal size: Mallampatti test (Dr.S.Rao Mallampati): sitting position,head neutral,mouth wide open,tongue protruding to its maximum(not to phonate) Class I : soft palate, fauces,uvula, anterior and posterior pillars. Class II : soft palate, fauces and uvula. Class III : soft palate and base of uvula. (samsoon & young 1987) Class IV : Hard palate only. Its indirect means of relative proportionality so it should be repeated twice to avoid false positive/ negative.

Failure of Mallampati Failure to include evaluation of two important factors affecting visualization of glottis Neck mobility Size of mandibular space

i) AO extension- sniffing or magill position Oral,Pharyngeal,Laryngeal axis--straight line Angle traversed by occlusional surface of upper teeth. Grade I : >35*-- (N) Grade II : 22-34* Grade III: 12-21* Grade IV : <12* For movement at A-O joint ask patient to place the chin on the chest, clasp both hands behind the neck, pull downwards and try to move head upwards.

Mandibular Space Sternomental distance-(savva 1948) <12.5cm predicts diff. intubation(PPV 82%) Inter incisor distance- 6 cm or 3 fingers---(N) <4 cm-makes intubation difficult. <2.5cm-LMA insertion will be difficult. Intraoral/ pharyngeal masses e.g tumours or lingual tonsils (difficult LMA)

Thyromental Distance-3 fingers? T-M distance(patil’s test)—with neck fully extended 6cm ---normal <3 fingers(<6 cm) difficult(75%) Combined Patil and mallampati tests (<6cm and class 3-4)increases specificity(97%)

Hyo-mental distance: distance btw mentum and hyoid Grade I :<4cm(2 fingers)--normal Grade II :4-6 cm Grade III >6cm

Wilson score ≤5 Easy intubation; 8-10 very difficult intubation Parameter 1 2 Weight (kg) < 90 90 – 110 > 110 Head & neck movement > 90 = 90 IID > 5 = 5 < 5 Receding mandible None Moderate severe Buck teeth ≤5 Easy intubation; 8-10 very difficult intubation

A total score of >0r =2 predicts 75% of difficult intubation;12% False positives. 2)Ame &co –wilson + airway pathology(+ or-) Sensitivity and specificity ----90%

LEMON Airway assessment (Dr. Binnions Lemon ) L= Look externally (facial trauma, large incisors, beard or moustache, large tongue) E= Evaluate the 3-3-2 rule (incisor distance-3 finger breadths, thyroid-mental distance-3 finger breadths, mento-to-hyoid distance-2 finger breadths) M= Mallampati scoring O= Obstruction (presence of any condition like peritonsillar abscess, trauma,edema,foreign body). N= Neck mobility (limited neck mobility) The score with a maximum of 10 points is calculated by assigning 1 point for each . Patients in the difficult intubation group have higher LEMON scores.

Direct laryngoscopy and fibreoptic bronchoscopy Cormack and Lehane(1984) defined 4 Grades Grade I – Visualization of entire laryngeal aperture. Grade II – Visualization of only posterior commissure of laryngeal aperture. Grade III – Visualization of only epiglottis. Grade IV – Visualization of just the soft palate. Grade III and IV predict difficult intubation.

Cook’s modification(1999) Grade IIa: visualization of posterior part of vocal cord. Grade IIb :only arytenoid seen. Grade IIIa:epiglotis liftable. Grade IIIb:epiglotis adherent. Grade I & IIa can be intubated easily. Grade IIb & IIIa needs some support(bougie) Grade IIIb & IV requires alt. techniques.

Mouth classification: M : Mallampatti classification , mandibular space) O : Obesity,opening of mouth) U : Upper lip bite T : Teeth H :Head and neck movement. *(The only system which includes upper lip bite test) Other scoring systems: a)MOANS(mask seal,obesity,age,no teeth,stiff lungs) b)RODS(restrcted oral opening,obstruction,distorted,stiff lungs) c)4Ds(dentition,distortion,disproportion,dismobility) d)LMMAP(look,mallampatti,measurement,A-O extn.,pathology of teeth)

collagen disorders: (Diabetic stiff joint syndrome) Palm print: Grade 0 – All the phalangeal areas are visible. Grade 1 – Deficiency in the interphalangeal areas of the 4th and 5th digits. Grade 2 – Deficiency in interphalangeal areas of 2nd to 5th digits. Grade 3 – Only the tips of digits are seen

Prayer sign : Patient is asked to bring both the palms together as ‘Namaste’ and sign is categorized as– Positive – When there is gap between palms. Negative – When there is no gap between palms. If positive: Grade I-metacarpo-phalangeal gap Grade II-proximal interphlyngeal involved Grade III- distal interphalyngeal joint is also involved

Radiological investigations

Radiological assessment i . Mandibulo-hyoid distance ii . Atlanto-occipital gap(5mm)Longer the A-O gap, more space is available for mobility of head at that joint with good axis for laryngoscopy and intubation. iii. Relation of mandibular angle and hyoid bone with cervical vertebra and laryngoscopy grading : Difficult when the mandibular angle tended to be more rostral and hyoid bone to be more caudal. iv. Anterior/Posterior depth of the mandible (<3.6) White and Kander (1975) v. C1-C2 gap vi.Calcified stylohyoid ligaments :Difficult because of inability to lift the epiglottis from posterior pharyngeal wall.

Other Radiological investigations Fluoroscopy for dynamic imaging for cord mobility,airway malacia. Ultrasonography- Ant. Mediastinal mass,lymohadenopathy,d/d cyst from mass,cellulitis from abssess CT/MRI – congenital anomalies.

Conclusion No single airway test can provide a high index of sensitivity and specificity for prediction of difficult airway. Therefore it has to be a combination of multiple tests. It must be recognized, however, that some patients with a difficult airway will remain undetected despite the most careful preoperative airway evaluation. Thus , anesthesiologists must always be prepared with variety of preformulated and practiced plans for airway management in the event of an unanticipated difficult airway.

This is my airway thanks