Airway assessment

1. Preoperative Airway Assessment Dr MANISH KHANDELWAL SMS MEDICAL COLLEGE MODERATOR Dr AMIT KULSHRESTHA

2. Airway The passage through which the air passes during respiration Nasal and oral cavities Pharynx Larynx Trachea and large bronchi

3. Why it is necessary ?? 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. 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

4. Difficult airway ASA definition of difficult airway: “The clinical situation in which a conventionally trained anaesthetist experiences difficulty with mask ventilation, difficulty with tracheal intubation or both.”

5. Difficult ventilation The inability of a trained anesthetist 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.

6. Difficult intubation More than 3 attempts Longer than 10 minutes Failure of optimal best attempt

7. Prevalence Difficult face mask 0.1% - 5% Difficult LMA 0.2% - 1% Difficult intubation 1-2% of normal surgical population 50% of rheumatic cervical disease

8. Components of the Airway Examination Nostril patency Length of the upper incisors, alignment   Condition of the teeth   Relationship of the upper (maxillary) incisors to the lower ( mandibular ) incisors   Ability to protrude or advance the lower ( mandibular ) incisors in front of the upper (maxillary) incisors   Interincisor or intergum (if edentulous) distance   Tongue size   Visibility of the uvula e.g. mallampati   Presence of heavy facial hair   Compliance of the mandibular space   Thyromental distance with the head in maximum extension   Length of the neck   Thickness or circumference of the neck   Range of motion of the head and neck Cheek pad

9. Causes of difficult airway Stiffness Arthritis of neck/jaw/larynx. Fixation devices Scleroderma Diabetes Deformity Cervical and craniofacial Burns/trauma/infection Swelling Infection/ tumour /trauma/burns Anaphylaxis/ haematoma / acromegaly Reflexes Cough/ breathholding Laryngospasm /salivation/regurgitation Foreign body Other – Pregnant/full stomach

10. Airway assessment History Patient/notes/chart/medic-alert/spam letter Difficulty Surgery/burns Concurrent disease Reflux/recent meals General examination Do they just look difficult? 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) Massively obese or pregnant Beards +/- tubes Specific tests/indices Investigations. Nasoendoscopy X-ray, CT/MRI Flow volume loop

11. How do you assess ?? The 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.

12. Predictors of difficulty to face mask ventilate (OBESE) The O bese (body mass index > 26 kg/m2) The B earded The E lderly (older than 55 y) The S norers The E dentulous (=BONES)

13. Predictors of difficulty to face mask ventilate (MOANS) MOANS This is identicle to BONES except ‘M’. - M ask seal difficult due to receding mandible,syndromes with facial abnormalities,burn stricture etc. - O besity, upper airway Obstruction - A dvanced age - N o teeth - S norer

14. Predictors of difficult laryngoscopy and intubation Individual indices -Physical examination indices -radiological indices -advanced indices Group indices - Wilson’s score - Benumof’s analysis - Saghei & safavi test - Lemon assesment - Arne’s simplified score - Magboul’s 4 M’s -

15. Atlanto-occipital movement The patient is asked to hold head erect, facing directly to the front, then he is asked to extend the head maximally and the examiner estimates the angle traversed by the occlusal surface of upper teeth. Visual assessment or using a goniometer. Grade I >35 degrees Grade II 22-34 degrees Grade III 12–21 degrees Grade IV <12 degrees Assesses feasibility to make the optimal intubation position with alignment of oral, pharyngeal and laryngeal axes into a straight line. Limited A-O joint extension Spondylosis, rheumatoid arthritis, halo-jacket fixation, and in patients with symptoms indicating nerve compression with cervical extension.

16. Grade Reduction of A.O.Extension 1 none 2 One third 3 Two third 4 complete Grades 3 and 4 : Difficult laryngoscopy Grading of reduction in A.O.Extension Grade I : > 35° Grade II : 22-34° Grade III : 12-21° Grade IV : < 12°

17. ASSESMENT OF A.O. EXTENSION Flexion movement of the cervical spine can be assessed by asking the patient to touch his manubrium sternii with his chin. If done, the above maneuver assures a neck flexion of 25- 35 degree. Flexion and the extension movement if within the normal range ,three axis ( oral,pharyngeal & laryngeal axis) can be brought into a straight line. can also be done by asking the patient to look at the floor and at wall after fully flexing and fixing the neck as shown

18. 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.

19. 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.

20. Palm Print test T he 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 5 th digit. * Grade2 - Deficiency in the inter- phalangeal areas of 2nd to 5 th digit. * Grade 3 - Only the tips of digits seen.

21. Palm Print as a Predictor of Difficult Airway in DM

22. ASSESSMENT OF TMJ FUNCTION TM joint exhibits 2 function. Rotation of the condyle in the s.cavity. Forward displacement of the condyle. First movement is responsible for 2-3cm mouth opening & the second is responsible for further 2-3cm mouth opening. 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 intented in its space and the thumb can feel the sliding movement of the condyle as the condyle of the mandible slides forward. SUBLUXATION OF THE MANDIBLE

23. Significance- Class B and C: difficult laryngoscopy

24. Assessment of mandibular space can be expressed as thyromental and hyomental space. This space determines how easily the laryngeal and pharyngeal axis will fall in line when the a-o joint is extended.

25. Thyromental Distance Measure from upper edge of thyroid cartilage to chin with the head fully extended. Normal is approx 7cm . 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

26. Limitations Little reliability in prediction Variation according to height, ethnicity Modification to improve the accuracy Ratio of height to thyromental distance (RHTMD) Useful bedside screening test RHTMD > 23.5 – very sensitive predictor of difficult laryngoscopy Thyromental Distance PATIL’S TEST

27. HYO MENTAL DISTANCE Distance between mentum and hyoid bone Grade I : > 6cm Grade II: 4 – 6cm Grade III : < 4cm – Impossible laryngoscopy & Intubation

28. 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

29. 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).

30. UPPER LIP BITE /CATCH TEST Class 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 lip Significance Assessment of mandibular movement and dental architecture Less inter observer variability

31. Test for assessing adequacy of the oropharynx for laryngoscopy and intubation Mallampati grading (samsoon and young’s modification) Narrowness of the palate

32. Mallampati Score Class I (easy)—visualization of the soft palate, fauces, uvula, and both anterior and posterior pillars Class II—visualization of the soft palate, fauces , and uvula Class III—visualization of the soft palate and the base of the uvula Class IV (difficult)—the soft palate is not visible at all Sensitivity: 44% - 81% Specificity: 60% - 80% Roughly corresponds to Cormack and Lehane’s laryngoscopy views

33. SIGNIFICANCE OF MMP SCORE Class III or IV : signifies that the angle between the base of tongue and laryngeal inlet is more acute and not conducive for easy laryngoscopy Limitations Poor interobserver reliability Limited accuracy Good predictor in pregnancy, obesity, acromegaly

34. Assessment for quality of glottic viewing during laryngoscopy Indirect mirror laryngoscopic view Direct laryngoscopy ‘awake look’ -cormack and lehane grading Grading ease of intubation POGO (percentage of glottic opening) scoring

35. 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

36. Group indices - Wilson’s score - Benumof’s analysis - Saghei & safavi test - Lemon assesment - Arne’s simplified score - Magboul’s 4 M’s - 4D’s

37. Wilson’s risk score Score Weight 0=<90kg 1=>90kg 2=>110kg Head and neck movement 0=Above 90degrees 1=About 90degrees 2=Below 90degrees Jaw movement 0=IG>5cm or SLux >0 1=IG<5cm and SLux = 0 2=IG<5cm and SLux <0 Receding mandible 0=Normal 1=Moderate 2=Severe Buck teeth 0=Normal 1=Moderate 2=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 or < =easy laryngoscopy Score 8-10 =severe difficulty in laryngoscopy

38. BENUMOF’S 11 PARAMETER ANALYSIS Parameter Buck teeth Subluxation Interincisor gap Palate configuration Mallampati class Upper inciors length Minimum acceptable value <1.5cm Absent Yes >3cm No arching/narrowness <2 7. TM distance 8. SMS compliance 9. Neck thickness 10. Length of neck 11. Head /neck mvt > 5cm Soft to palpation. Qualitative ( >33cm DI) >8cm Normal range 2 for mandibular space 3 for neck examination. 4-2-2-3 rule 4 for tooth 2 for inside of mouth

39. 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

40. Arne’s simplified score model The points of simplified score were obtained by multiplying the points of the exact score by 3.15 and then rounding the results to the nearest whole number. 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

41. Arne’s simplified score contd. 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...... 48 Score of >11 is predictive of difficult tracheal intubation Indian journal of anaesthesia,2002; 46(5) 347-352

42. LEMON trial L ook Facial trauma Large incisors Beard Large tongue E valuate 3-3-2 Interincisor distance (3 fingers) Hyoidmental distance (3 fingers) Thyroid to floor of mouth (2fingers) M allampati O bstruction N eck movement – chin to chest ( Airway management in trauma Indian J Anaesth . 2011 Sep-Oct; 55(5): 46)3–469)

43. 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

44. EVALUATE 3-3-2 Mouth Opens at least 3 finger widths. Three finger widths thyromental distance. Two finger widths mandibulohyoid distance.

45. Mouth opens at least 3 fingers width?

46. Upper & Lower Face Measure the size of the upper face as compared to the lower face. Should be roughly the same. If the lower face is longer than the upper face then you should anticipate some degree of difficulty lining up the structures

47. Upper and lower face equal?

48. Upper and lower face equal?

49. Obstruction Laryngoscopy or intubation may be more difficult in the presence of an obstruction Anatomy Trauma Foreign body obstruction Edema (burns)

50. Neck Mobility Ideally the neck should be able to extend back approximately 35 ° Problems: Cervical Spine Immobilization Ankylosing Spondylitis Rheumatoid Arthritis Halo fixation

51. Scene and Situation (SEE ) Scene safety Environment Do you have a reasonable chance to get the tube? Space, positioning, access Egress Will you be able to ventilate during egress?

52. Magboul’s 4 M’s For Intubation remember the 4(M & Ms) with (STOP) sign M allampati M easurement M ovement M alformation & 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) . (The Internet Journal of Anesthesiology . 2005 Volume 10 Number 1. DOI: 10.5580/1d0a)

53. What are the 4 Ds? The following  Four D's  also suggest a difficult airway: D entition (prominent upper incisors, receding chin) D istortion (edema, blood, vomits, tumor, infection) D isproportion (short chin-to-larynx distance, bull neck, large tongue, small mouth) D ysmobility (TMJ and cervical spine)

54. 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. RADIOGRAPHIC PREDICTORS

55. 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 Flow volume loop Acoustic response measurement Ultra sound guided CT / MRI Flexible bronchoscope ADVANCED INDICES

56. Difficult Airway DOA Disruption or Distortion Obstruction Access Problems DOA

57. Disruption / Distortion Distortion Surgeries Radiation Therapy Scarring Burns DOA

58. Disruption / Distortion Disruption Hanging Crush Injuries Penetrating Trauma Other Soft Tissue Trauma Burns Laceration DOA

59. Obstructions Hematoma Abscess Tumor Tumors can also create distortions & extra bleeding DOA

60. Access Issues Obesity Halo Short neck SC Emphysema Bushy beard Flexion deformity of the spine DOA

61. 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 (Canadian journal of anesthesia 2004:10:963-8)

62. How to predict difficulty in creating surgical airway (BANG) Bleeding tendency Agitated patient Neck scarring Growth or vascular abnormality in region of surgical airway.

63. Why would this man’s airway be difficult to manage?

64. COPUR index assessing difficult airway in paediatric patient C -chin From the side view the chin is: score Normal 1 Small, moderately hypoplastic 2 Markedly recessive 3 Extremely hypoplastic 4 O -Opening of the mouth(Interdental space) > 40mm 1 20-40 mm 2 10-20mm 3 <10 4 P -Previous Intubation or OSA Previous attempt easy 1 No previous attempt, no hx OSA 2 OSA, previous hx difficult intubation 3 Extremely difficult previous intubation, trach, or patient unable to lie supine 4

65. COPUR index ( contd ) U -Uvula (Mouth open tongue out) Tip of uvula visible 1 Uvula partially visible 2 Uvula concealed, soft palate visible 3 Soft palate not visible 4 R Range (estimaterange of motion looking up and down) >120° 1 60°-120° 2 30°-60° 3 < 30° 4 Prediction Points 5-7 Easy normal intubation score >10 predict difficult airway 8-10 laryngeal pressure may help 12 more difficult, fiberoptic may be less traumatic 14 Difficult intubation, fiberoptic or other advanced technique 16 Dangerous airway, consider awake intubation, potential trach O

66. Structured Approach to Airway Management MOUTHS Component Description Assessment Activities M andible Length and subluxation Measure hyomental distance and anterior displacement of mandible O pening Base, symmetry, range Assess and measure mouth opening in centimetres U vula Visibility Assess pharyngeal structures and classify T eeth Dentition Assess for presence of loose teeth and dental appliances H ead Flexion, extension, rotation of head/neck and cervical spine Assess all ranges and movement S ilhouette Upper body abnormalities, both anterior and posterior Identify potential impact on control of airway of large breasts, buffalo hump, kyphosis, etc.

67. Rule of 1-2-3 1 finger breadth for subluxation of mandible. Just to recall 2 finger breatdh for adequacy of mouth opening. 3 finger breathd for hyomental distance. In emergency situation, above test can be rapidly performed within 15sec to assess the TMJ function,mouth opening and SM Space. Significant difficulty in 2 or more of these components requires detailed examination. 4 finger breath for thyromental distance 5 movements- ability to flex the neck upto the manubrium sterni, extension at the AOJ, rotation of the head along with right & left movement of the head to touch the shoulder. Rule of 1-2-3-4-5 3 finger in the interdental space. 3 finger between mentum and hyoid bone. 3 finger between thyroid cartilage & sternum. Significant difficulty in 2 or more of these components requires detailed examination. RULE OF THREE`S

68. 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 ! Nothing is more expensive than the missed opportunity

69. References Airway management in trauma Indian J Anaesth. 2011 Sep-Oct; 55(5): 463–469. The Internet Journal of Anesthesiology ISSN: 1092-406X The Dilemma of Airway Assessment and Evaluation Magboul M. Ali Magboul MD, FFARCSI Clinical Assistant Professor, Director of ACLS, PALS & Airway workshop, Department of Anesthesia, University of IowaIowa City, Iowa U.S.A. Citation:   M.M. Ali Magboul: The Dilemma of Airway Assessment and Evaluation. The Internet Journal of Anesthesiology . 2005 Volume 10 Number 1. DOI: 10.5580/1d0a Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2003; 98 (5):1269-77 Frerk CM. Predicting difficult intubation. Anaesthesia 1991; 46 (12):1005-8 Verghese C, Brimacombe JR . Survey of laryngeal mask airway usage in 11,910 patients: safety and efficacy for conventional and nonconventional usage. Anesth Analg 1996; 82: 129–33 Gupta S, Sharma R, Jain D. Airway assessment – Predictors of a Difficult Airway. Indian Journal Of Anaesthetics 2005; 49(4) : 257 -262