Airway assessment

1. Airway Assessment Moderator: Dr. Hemalatha S Speaker: Dr. Deepa Sinha

2. Definition: AIRWAY: The passage through which the air passes during respiration. DIFFICULT AIRWAY :According to ASA it is defied as the clinical situation in which a conventionally trained anesthesiologis t is unable to maintain the oxygen saturation above 90 % by using face-mask ventillation .

3. DIFFICULT MASK VENTILATION According to ASA ‘ The clinical situation in which a conventionally trained anaestthesiologist experiences difficulty with mask ventilation, difficulty with tracheal intubation or both ’

4. Difficult Mask Ventilation: OBESE O: Obesity i.e. BMI>26 kg/m B: Beard E: Edentulous S: Snorer E: Elderly And also Difficult in maintain mask seal due to any anatomical, congenital or acquired factors.

5. Anatomy: PARTS OF AIRWAY Upper Airway: a. Mouth- opening of mouth to anterior tonsil or pillar. b. Nostrils- adult nose= anterior posterior diameter 1.5-2 cm ,transverse diameter 0.5-1cm c. Nasal Cavity-from nares to the end of the turbinates . d. Nasopharynx- extends from posterior end of turbinates to the posterior pharyngeal wall above the soft palate and consists of the nasal cavity , septum, turbinates and adenoids.

6. Oropharynx -extends from soft palate above to epiglottis below and anteriorly from anterior tonsillar pillar to posterior pharyngeal wall , it includes tonsil , uvula and the epiglottis. Pharynx- extends from the base of skull to lower border of cricoid cartilage

7. Larynx- extends form laryngeal inlet i.e C3-C4 to lower border of cricoid cartilage (C5-C6)-[ Importance : Phonation and Swallowing ] Contents : Unpaired Cartilage = Thyroid , Cricoid and Epiglottis , Paired = Arytenoid , Cornicuate and Cuneiform (most vulnarable area for obstruction and trauma during laryngoscopy)

8. 2 . Lower Airway : a. Trachea : extends from lower border of cricoid C6 to its division into the two main bronchi i.e till T4 it is 11-13 cm long .(Importance : Endotracheal tube lodges in the mid trachea) b. Bronchi and Bronchioles : Made up of fibrocartilage and has secretory bronchial gland cells.

9. Respiratory events are the most common anaesthetic related injuries, following dental damage. Three main causes: -Inadequate ventilation - Oesophageal intubation -Difficult tracheal intubation Difficult tracheal intubation accounts for 17% of the respiratory related injuries and results in significant morbidity and mortality.

10. Estimated that up to 28% of all anaesthetic related deaths are secondary to the inability to mask ventilate or intubate . Prediction of the difficult airway allows time for proper selection of equipment, technique and personnel experienced in difficult airways

11. Factors predisposing Difficult Airway: - Congenital : 1.Pierre Robin Syndrome 2. Treacher Collins Syndrome 3. Downs Syndrome 4. Kippel Feil Syndrome 5. Goiter - Acquired: Infections- Supraglottis , Croup, Abcess , Ludwig’s Angina, Sub Mucus Oral Fibrosis

12. -Arthritis: Rheumatoid arthritis Ankylosing Spondylitis -Benign Tumor: Cystic Hygroma Lipoma Adenoma -Malignant Tumor: -Facial Injury -Cervical Spine Injury -Laryngeal/Tracheal Trauma -Obesity - Acromegaly

13. Assessment: History Regional & Local Examinatio Specific test for assessment Radiographic presentation

14. 1) History: Should be conducted when ever its feasible i.e. before the initiation of anaesthetic care and airway management inorder to: - Detect any medical, surgical and anaesthetic factors. - Examination of previous medical records if available.

15. 2) General, Physical and regional Examination : a. Patency of nares b. Mouth Opening -2 large finger breadths between upper and lower incisors in adults. c. Teeth: Look for Prominent upper Incisors, Canines with or without over bitiong or edentulous state.

16. ( a) Shows mandibular advancement beyond the upper teeth. ( b) Shows that the mandible cannot be advanced beyond the upper teeth. (c) Shows that the lower incisors cannot reach the upper teeth. d. Palate e. Patients ability to protrude the lower jaw beyond the upper incisors .

17. f. Temporo-mandibular joint movement : restricted in ankylosis , tumors, fibrosis etc g. Measurement of Submental Space : atleast >6cm h. Patient’s Neck: For Sniffing Position i.e. ideal position for intubation. Look for: Short Neck, Thick neck Mass present in the neck Extension of neck Mobility of neck

18. i . Presence of Stridor/Hoarse voice or previous Tracheostomy may suggest Stenosis j. Systemic or Congenital Diseases k. Infection of Airway l. Physiologic Conditions: Pregnancy or Obesity

19. 3. Specific tests for Assessment A. Anatomical Criteria 1. Relative Tongue and Pharyngeal Size: Mallampatti Test: In 1983 Mallampatti SR gave a hypothesis i.e. clinical signs to predict difficult tracheal intubation. Which included only 3 Class.

20. Original Mallampati Scoring: Class 1: Faucial pillars, soft palate and uvula could be visualized. Class 2: Faucial pillars and soft palate could be visualized, but uvula was masked by the base of the tongue. Class 3: Only soft palate visualized.

21. Modified Mallampatti Grade: By Samsoon , GL; Young, JR (May 1987)   Soft palate Uvula

22. Class 1- Visualization of the Soft palate, faucial pillars, uvula and hard palate Class 2- Soft palate, fauces, uvula and hard palate Class 3- Soft palate, base of uvula and hard palate Class 4- only Hard palate Note : To avoid false positive or false negative, this test should be repeated twice

23. Grade 0: By Ezri  et al . proposed the addition of a new airway class 0 (epiglottis seen on mouth opening and tongue protrusion)

24. Atlanto Occipital Joint Extension : to assess Sniffing or Magill Position for intubation i.e. alignment of oral, pharyngeal and laryngeal axes. Patient is asked to hold neck erect, facing directly to the front and then he is asked to extend the head maximally and then the examiner estimates the angle transversed by the occlusal surface or can use Goniometer to assess more accurately.

25. Grading of Extension: Grade 1- >35 degrees Grade 2- 22 to 34 degrees Grade 3- 12 to 21 degrees Grade 4- <12 degrees

26. 3- Mandibular Space A. Thyromental Distance (T-M) aka Patil’s Test: Distance from Mentum to Thyroid notch when patient’s neck is fully extended. <3 finger (Patients) breadth or <6 cm in adults- Difficult 6-6.5cm- less difficult >6.5cm- Normal

27. B. Mandibular-Hyoid Distance : Distance from Chin to hyoid. Atleast Should be of 4 cm or 3 finger breadth. If the distance is more then laryngoscopy becomes more difficult C. Sterno-mental Distance : Distance from Sternal notch to the mentum. Measured when head is fully extended with mouth closed. If less than 12 cm, it indicated difficult intubation.

28. C. Inter-incisor distance: Distance between upper and lower incisors. Normal- 4.6cms Difficult- >3.8 cm

29. 4. Temporomandibular Joint : 1.The middle finger of each hand posterior and inferior to the patient’s earlobes, place your index fingers just anterior to the tragus and instruct the patient to open widely Two distinct movements should be felt: the first is rotational, & the second involves advancement of the condyler head . Listen and palpate for clicks and crepitus , both of which indicate joint dysfunction. 2.TMJ function may also be assessed by asking the patient to insert two or three fingers (of their own hand) held vertically, into the oral cavity in the midline.

30. Normal adults are capable of inserting at least three fingers, which corresponds to a range of mandibular opening between 40 and 60 mm. If the maximal mandibular opening is less than 30 mm in the adult, significant TMJ dysfunction is present. If less than 25 mm , it is unlikely that the larynx will be visible using conventional laryngoscopy If 20 mm or less , Keep alternate method ready

31. Different Scoring System: Scoring System By Wilson and Colleagues : They analyzed 5 parameters i.e. weight, head and neck movement, jaw movement, Sliding mandibular, receding mandible and buck teeth.

32. Parameters 1 2 Weight <90 90-100 >110 Head & Neck Movement >90 =90 degrees < 90 degrees Jaw Movement > 5 cm =5 cm < 5 cm Sliding mandible beyond incisors > 0 = < Receding mandible None Moderate Severe Buck Teeth None Moderate Severe Patient scoring 5 or< =Easy Laryngoscopy 6-7= Moderate 8-10= Severe difficulty

33. -LEMON Airway Assessment Method : L= Look externally i.e. facial trauma, large incisors, beard, moustache etc E= Evaluate 3-3-2 rule i.e. incisors distance- 3 fingers, Hyoid-mental-3 finger and thyroid-mouth- 2 finger M= Mallampatti O= Obstruction like tonsil, trauma, peritonsillar abscess N= Neck Mobility

34. 1 = Inter-incisor distance in fingers, 2 = Hyoid mental distance in fingers, 3 = Thyroid to floor of mouth in fingers

35. Magboul’s 4 M & Ms with (STOP) For assessing Difficult Airway: M= Mallampatti M= Measurement M= Movement M=Malformation and STOP S= Skull i.e. hydro or microcephalus T= Teeth O= Obstruction due to obesity, short neck, long neck, swelling in and around oral cavity P= Pathology i.e. Pierre Robinson Syndrome, Downs Syndrome etc

36. If a patient score 8 or more than 8, he/she is likely to be a difficult intubation. Score 1 2 3 4 Mallampatti Grade 1 Grade 2 Grade 3 Grade 4 Measurement 3 Mouth Opening 2 Thyromental 2 Hypo mental 1 Subluxation Movement Left Right Flexion Extension Malformation Skull Hydro/ Microcephalus Teeth/Buck teeth & Macro/Micro Jaw Obstruction Obesity Short/Bull neck & Swelling Pathology & Syndrome: -Pierre-Robinson -Treacher- Colins -Quinsy -Downs TOTAL 4 4 4 4

37.   -Benumof’s 11 parameter Analysis: Parameter Minimum acceptable value Weight <1.5 cm Buck teeth Absent Subluxation Yes Interincisor gap >3 cm Palate Configuration No arching/Narrowness Mallampatti <2 cm TM Distance >5 cm SMS Compliance Soft to palpate Neck thickness Qualitative (>33 cm) Length of neck >8 cm Head & Neck Movement Normal Range

38. Difficult Laryngoscopy: According to ASA : When it is not possible to visualize any portion of the vocal cords with conventional laryngoscope.

39. B. Direct Laryngoscopy and Fiberoptic Bronchoscopy : 4 grades of direct under laryngoscopic view by Cormack and Lehane (1984) 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

40. 5- Radiographic Assessment 1. From Skeletal Films a. Mandibular-Hyoid distance b. Atlanto-occipital gap. c. Relation of mandibular angle and hyoid bone with cervical vertebrae and laryngoscopy grading d. Anterior/posterior depth of mandible e. C1-C2 gap 1 = Effective mandibular length, 2 =Posterior mandibular depth, 3 = Anterior mandibular depth, 4 = Atlanto-occipital gap, 5 = C1 – C2 gap.

41. 2. Fluoroscopy for chords mobility and airway malacia . 3. Oesophagogram 4. USG 5. CT-Scan/MRI 6. Video optical intubation stylets.

42. 6. Predictors of difficult airway in diabetics: a. Palm Sign: The patient is made to sit; palm and fingers of right hand are painted with blue ink, patient then presses the hand firmly against a white paper placed on a hard surface. It is categorized as: 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.

43. Normal Abnormal

44. 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.

45. Summary of all the Tests: Six standards in the evaluation of airway a. Temporomandibular mobility – One finger b. Inspection of mouth, oropharynx – Mallampati classification – Two fingers c. Measurement of mento-hyoid distance (4 cm) in adult – Three fingers.

46. d. Measurement of distance from chin to thyroid notch – (5 to 6 cm) – Four fingers f. Ability to flex head towards chest, extend head at atlanto-occipital junction and rotate head, turn right and left (five movements). g. Symmetry of nose and patency of nasal passage.

47. Assessment of pediatric 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, prominence of upper incisors, range of motion of jaw, head and neck.

48. The presence of retractions (suprasternal/sternal/infrasternal/ intercostal) should be sought for they usually are signs of airway obstruction. Breath sounds – Crowing on inspiration is indicative of extrathoracic airway obstruction whereas, noise on exhalation is usually due to intrathoracic lesions.

49. Noise on inspiration and expiration usually is due to a lesion at thoracic inlet. Obtaining blood gas and O2 saturation is important to determine patient’s ability to compensate for airway problems. Transcutaneous CO2 determinations are very helpful in infants and young children.

50. Recent Advances: Ultrasound of the airway: to visualise anatomical structures in supraglottic , glottic and subglottic region. > 28 mm thickness of the pretracheal soft tissue & neck circumference > 50 cm indicate difficult intubation.

51. Conclusions: The importance of taking the time to conduct a thorough evaluation of the airway. That there is no single guaranteed test available to predict the problem airway. We need to ask ourselves a more fundamental question when dealing with airway issues. “Will I be able to oxygenate and ventilate this patient if or when he/she becomes unconscious?” We should be able to answer that question affirmatively in all cases, and if not, we need contingency plans.

52. Reference: Miller’s Anaesthesia 7 th Edition Airway Management By Rashid Khan 4 th Edition Indian Journal Of Anaesthesia, August 2005;49(4): 257-262 Indian Journal Of Anaesthesia, Sep 2011;55(5):456-457

53. Thank you