Transcript PRINCIPLES OF AIRWAY ASSESSMENT

PRINCIPLES OF
AIRWAY ASSESSMENT
Moderator : Dr. Anil Ohri
Presented by : Dr. Arun Kumar Sharma
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Airway: Extra pulmonary passage.
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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.
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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
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ASSESSMENT
History and physical examination:
 History : Medial , surgical and anesthetic
factors.
 Anesthetic factors: edema , burns , bleed,
tracheal compression , pneumothorax or
aspiration of gastric contents.
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PHYSICAL EXAMINATION
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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 affectinga) Presence of beard
b) Disfiguring malignancy of jaw
c) BMI >26
d) Absence of teeth
e) Age >55
f)
H/o snoring
g) Obstuctive sleep apnoea
h) Mallampati class 3&4
SPECIFIC TESTS
Based on tongue/ pharyngeal size:
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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
1.
2.
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*
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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)
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THYROMENTAL DISTANCE-3 FINGERS?
T-M distance(patil’s test)—
with neck fully extended
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6cm ---normal
<3 fingers(<6 cm) difficult(75%)
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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
Parameter
0
1
2
Weight (kg)
< 90
90 – 110
> 110
Head & neck
movement
IID
> 90
= 90
< 90
>5
=5
<5
Receding mandible None
Moderate
severe
Buck teeth
Moderate
severe
None
≤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.
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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.
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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.
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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)
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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
The “prayer sign” indicates the presence of diabetic cheiroarthropathy.
Kim R P et al. Clin Diabetes 2001;19:132-135
Copyright © 2011 American Diabetes Association, Inc.
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.
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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.