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1. Preoperative AirwayAssessmentDr MANISH KHANDELWALSMS MEDICAL
COLLEGEMODERATORDr AMIT KULSHRESTHA
2. AirwayThe 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
4. Difficult airwayASA 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 AirwayExamination 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)1.
The Obese (body mass index > 26 kg/m2)2. The Bearded3. The
Elderly (older than 55 y)4. The Snorers5. The Edentulous
(=BONES)
13. Predictors of difficulty to facemask ventilate (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
14. Predictors of difficultlaryngoscopy and
intubationIndividual indices -Physical examination indices
-radiological indices -advanced indicesGroup indices - Wilsons
score - Benumofs analysis - Saghei & safavi test - Lemon
assesment - Arnes simplified score - Magbouls 4 Ms
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 1221 degrees Grade IV 35 Grade II : 22-34 Grade
III : 12-21 Grade IV: < 12 Grade Reduction of A.O.Extension 1
none 2 One third 3 Two third 4 complete Grades 3 and 4 : Difficult
laryngoscopy
17. ASSESMENT OF A.O. EXTENSION 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 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
18. Warning sign of DELIKANPlace 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 testThe palm and fingers of the dominant hand of
thepatient is painted with black writing ink using a brush. The
patient then presses the hand firmly against a whitesheet 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.
21. Palm Print as a Predictor ofDifficult Airway in DM
22. ASSESSMENT OF TMJ FUNCTION TM 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
intented in its space and the thumb can feel the sliding movement
of the condyle as the condyle of the mandible slides forward.
23. Significance-Class B and C: difficult laryngoscopy
24. Assessment of mandibularspace 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 DistanceMeasure from upper edge of
thyroidcartilage to chin with the head fullyextended. Normal is
approx 7cm.If the thyromental distance is short, 23.5 very
sensitive predictor of difficult laryngoscopyThyromental Distance
PATILS 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 (SAVVATEST) 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
lipSignificance Assessment of mandibular movement and dental
architecture Less inter observer variability
31. Test for assessing adequacy ofthe oropharynx for
laryngoscopyand intubation Mallampati grading (samsoon and youngs
modification) Narrowness of the palate
32. Sensitivity: 44% - 81% Mallampati Score Specificity: 60% -
80% Roughly corresponds to Cormack and Lehanes laryngoscopy views
Class I (easy)visualization of the soft palate, fauces, uvula, and
both anterior and posterior pillars Class IIvisualization of the
soft palate, fauces, and uvula Class IIIvisualization of the soft
palate and the base of the uvula Class IV (difficult)the soft
palate is not visible at all
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 glotticviewing during
laryngoscopyIndirect mirror laryngoscopic viewDirect laryngoscopy
awake look -cormack and lehane gradingGrading ease of
intubationPOGO (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 - Wilsons score - Benumofs analysis - Saghei
& safavi test - Lemon assesment - Arnes simplified score -
Magbouls 4 Ms - 4Ds
37. Wilsons risk score Score Head movement assessedWeight
0=90kg patients forehead. 2=>110kg IG = Interincisor gapHead and
0=Above 90degreesneck 1=About 90degrees measured with mouth
fullymovement 2=Below 90degrees open.Jaw 0=IG>5cm or SLux >0
SLux = Maximal forwardmovement 1=IG80kg Tongue protrusion <
3.2cm Mouth opening 1.5cm Mallampati class >1 Head extension 5
cm or ML >0 0 IG 3.5-5cm and ML=0 3 IG11 is predictive of
difficult tracheal intubationIndian journal of anaesthesia,2002;
46(5) 347-352
42. LEMON trial Look 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)
Mallampati Obstruction Neck movement chin to chest( Airway
management in traumaIndian J Anaesth. 2011 Sep-Oct; 55(5):
46)3469)
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 fingerswidth?
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. Magbouls 4 Ms 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, Goldenhars, 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 Ds 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)
54. 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 40mm 1 20-40 mm 2 10-20mm 3 120 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
66. Structured Approach to Airway Management MOUTHSComponent
Description Assessment ActivitiesMandible Length and subluxation
Measure hyomental distance and anterior displacement of
mandibleOpening Base, symmetry, range Assess and measure mouth
opening in centimetresUvula Visibility Assess pharyngeal structures
and classifyTeeth Dentition Assess for presence of loose teeth and
dental appliancesHead Flexion, extension, rotation of head/neck and
cervical Assess all ranges and movement spineSilhouette 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. Rule of
1-2-3-4-5 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 THREE`S 3 finger in the
interdental space. 3 finger between mentum and hyoid bone. 3 finger
between thyroid cartilage & sternum.
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 intubationBe Prepared! Nothing is more
expensive than the missed opportunity
69. References Airway management in trauma Indian J Anaesth.
2011 Sep-Oct; 55(5): 463469. The Internet Journal of Anesthesiology
ISSN: 1092-406X The Dilemma of Airway Assessment and Evaluation
Magboul M. Ali Magboul MD, FFARCSIClinical 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: 12933 Gupta S, Sharma R, Jain D. Airway
assessment Predictors of a Difficult Airway. Indian Journal Of
Anaesthetics 2005; 49(4) : 257 -262