Airway

1. Airway assessment
Airway assessment
Dr sanjit kumar singh
Dr sanjit kumar singh

2. Introduction
Introduction
 Respiratory events are the most common anaesthetic related
Respiratory events are the most common anaesthetic related
injuries, following dental damage. Three main causes:
injuries, following dental damage. Three main causes:
– Inadequate ventilation
Inadequate ventilation
– Oesophageal intubation
Oesophageal intubation
– Difficult tracheal intubation
Difficult tracheal intubation
 Difficult tracheal intubation accounts for 17% of the respiratory
Difficult tracheal intubation accounts for 17% of the respiratory
related injuries and results in significant morbidity and
related injuries and results in significant morbidity and
mortality.
mortality.
 Estimated that up to 28% of all anaesthetic related deaths are
Estimated that up to 28% of all anaesthetic related deaths are
secondary to the inability to mask ventilate or intubate.
secondary to the inability to mask ventilate or intubate.
 Prediction of the difficult airway allows time for proper
Prediction of the difficult airway allows time for proper
selection of equipment, technique and personnel experienced in
selection of equipment, technique and personnel experienced in
difficult airways
difficult airways

3. Airway
Airway
Nasal and oral
Nasal and oral
cavities
cavities
Pharynx
Pharynx
Larynx
Larynx
Trachea and large
Trachea and large
bronchi
bronchi

4. Goals of preoperative
Goals of preoperative
assessment
assessment
• History and physical examination to
determine relevant tests and
consultations
• Guided by patient choice and medical
risk factors choose a plan of care
• Informed consent
• Educate patient about anaesthesia, pain
management and perioperative care
• Reduce patient care costs

5. Mortality related to anaesthesia
Mortality related to anaesthesia
• One third of deaths are preventable
• Causes in order of frequency
– inadequate patient preparation
– inadequate postoperative management
– wrong choice of anaesthetic technique
– inadequate crisis management

6. Predicting the Difficult Airway
• History
• General, Physical and regional Examination
• Specific test for assessment

7. History and
History and
physical are the
physical are the
most important
most important
assessors of
assessors of
disease and risk
disease and risk

8. HISTORY
• Medical history
• Surgical history
• Anaesthetic history

9. Presenting complaint
Presenting complaint
Why does the patient need an operation now?
• Is it acute/chronic illness?
• Presenting symptoms?
e.g. anaemia, cachexia, pain, seizures etc
• What are the pathophysiological consequences?
e.g. thyroid mass
– Local - stridor, SVC obstruction
– Systemic - hypo/hyperthyroidism

10. Associated medical conditions
Associated medical conditions
Given the presenting problems are there any other
conditions I am worried the patient could have?
• Bowel ca. - liver mets with abnormal LFTs,
abnormal coagulation, impaired drug metabolism
• Peripheral vascular disease - IHD, carotid disease,
HT, renal disease, COAD

11. Other medical conditions
Other medical conditions
Any other problems that may affect
perioperative morbidity and mortality?
• cardiac disease
• respiratory disease
• arthritis
• endocrine disease - diabetes, obesity etc
What is the patients functional capacity?

12. Functional capacity
Functional capacity
• 1 MET Can you dress yourself?
• 4 MET Can you climb a flight of stairs?
• 10 MET Can you participate in strenuous
activities
(swimming, tennis, football)

13. Physical demand characteristics of work
(1993 Leonard Matheson & Ministry of Labor)
Physical
Demand
Level
Occasional
0-33% work
day
Frequent
34-66% of
workday
Constant
67-100% of
workday
Typical Energy
Required
Sedentary 10 lbs Negligible Negligible 1.5 -2.1 METS
Light 20 lbs 10 lbs Negligible 2.2 – 3.5
METS
Medium 20-50 lbs 10-25 lbs 10 lbs 3.6 – 6.3
METS
Heavy 50-100 lbs 25-50 lbs 10-20 lbs 6.4 – 7.5
METS
Very
Heavy
Over 100
lbs
Over 50
lbs
Over 20 lbs Over 7.5
METS

14. Anaesthetic history
Anaesthetic history
• Family history
• Previous anaesthetics
– PONV
– allergy
– malignant hyperpyrexia
– difficult airway
– difficult IV access

15. ANAESTHETIC FACTORS
o Edema
o Compression or
perforation
o Pneumothorax
o Aspiration of gastric
contents
o Burns
o Bleeding
o Tracheal/oesophageal
stenosis

16. Drug history
Drug history
Very useful, often forgotten
• Current medications
• ALLERGY
• Medic alert bracelets
• Smoking/alcohol history
• Other drugs of abuse!

17. General, physical and regional
examination
i. Patency of nares : look for masses inside
nasal cavity
(e.g. polyps) deviated nasal septum, etc.
ii. Mouth opening of at least 2 large finger
breadths
iii. Teeth : Prominent upper incisors, or
canines

18. iv. Palate : A high arched palate or a long, narrow
mouth
may present difficulty.
v. Assess patient’s ability to protrude the lower
jaw
beyond the upper incisors (Prognathism).
vi. Temporo-mandibular joint movement : It can
be
restricted ankylosis/fibrosis, tumors, etc.
vii. Measurement of submental space (hyomental/
Thyromental length > 6 cm)

19. viii. Observation of patient’s neck : A short, thick
neck
ix. Presence of hoarse voice/stridor or previous
tracheostomy may suggest stenosis
x. Infections of airway (e.g. epiglottitis, abscess,
croup,
bronchitis, pneumonia).
xi. Physiologic conditions : Pregnancy and obesity

20. Specific tests for assessment
Anatomical criteria
1. Relative to tongue/pharyngeal size

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

22. Thyromental distance
Thyromental distance
Measure from upper edge of
Measure from upper edge of
thyroid cartilage to chin with
thyroid cartilage to chin with
the head fully extended.
the head fully extended.
– Normal is approx 7cm
Normal is approx 7cm
Relatively unreliable test unless combined with
Relatively unreliable test unless combined with
other tests.
other tests.
– Grade 3 or 4 Mallampati who also had a thyromental
Grade 3 or 4 Mallampati who also had a thyromental
distance of less than 7cm were likely to present
distance of less than 7cm were likely to present
difficulty with intubation.
difficulty with intubation.
» Sensitivity: 90.9% Specificity: 81.5%
Sensitivity: 90.9% Specificity: 81.5%

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

24. Further assessments
Further assessments
 Sterno-mental distance
Sterno-mental distance
– Measured from the sternum to the tip of the mandible
Measured from the sternum to the tip of the mandible
with the head extended.
with the head extended.
» A sternomental distance of 12.5cm predicts a difficult
A sternomental distance of 12.5cm predicts a difficult
intubation.
intubation.
 Mandibular protrusion
Mandibular protrusion
– If the patient is able to protrude the lower teeth beyond
If the patient is able to protrude the lower teeth beyond
the upper incisors intubation is usually straightforward
the upper incisors intubation is usually straightforward
– If the patient cannot get the upper and lower incisors
If the patient cannot get the upper and lower incisors
into alignment intubation is likely to be difficult.
into alignment intubation is likely to be difficult.

25. Dr. Binnions Lemon Law: An easy way to
remember multiple tests…
• Look externally.
• Evaluate the 3-3-2 rule.
• Mallampati.
• Obstruction?
• Neck mobility.

26. L: Look Externally
• Obesity or very small.
• Short Muscular neck
• Large breasts
• Prominent Upper Incisors (Buck Teeth)
• Receding Jaw (Dentures)
• Burns
• Facial Trauma
• Stridor
• Macroglossia

27. E-Evaluate the 3-3-2 rule
27
 3 fingers fit in mouth
 3 fingers fit from mentum
to hyoid cartilage
 2 fingers fit from the floor
of the mouth to the top of
the thyroid cartilage

28. M- Mallampati classification
Class-1 Class-11
Class-111 Class-1V
soft palate, fauces;
uvula, anterior and
the posterior pillars.
the soft palate, fauces
and uvula
soft palate and base of uvula Only hard palate

29. O: Obstruction?
 Blood
Blood
 Vomitus
Vomitus
 Teeth
Teeth
 Epiglottis
Epiglottis
 Dentures
Dentures
Tumors
Tumors
 Impaled Objects
Impaled Objects

30. N-Neck mobility -Measurement of
Atlanto-Occepital Angle

31. DIRECT LARYNGOSCOPY &
FIBREOPTIC BRONCHOSCOPY
Cormack & Lehane Grading

32. Radiographic assessment
1. From skeletal films (by measuring diff. length)
2. Fluoroscopy for dynamic imaging (cord mobility,
airway malacia, and emphysema).
3. Oesophagogram (inflammation, foreign body,
extensive mass or vascular ring).
4. Ultrasonography (mediastinal mass,
lymphadenopathy, cyst, cellulitis & abscess
5. Computed tomography/MRI (congenital
anamolies, vascular airway compression).
6. Video-optical intubation stylets).

33. Predictors of difficult airway in
diabetics
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.

34. 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.

35. Assessment of paediatric
airway
History
 complaints of snoring, apnoea, day time
somnolence, stridor, hoarse voice and prior surgery
or radiation treatment to face or neck
 History of previous anaesthetic records with
attention being paid to history of oropharyngeal
injury, damage to teeth, awake tracheal intubation or
postponement of surgery following an anaesthetic.

36. 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.
The presence of retractions (suprasternal/sternal/
infrasternal/ intercostal) should be sought for they
usually are signs of airway obstruction.

37.  Breath sounds – Crowing on inspiration is
indicative of extrathoracic airway obstruction
whereas, noise on exhalation is usually due to
intrathoracic lesions.
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.

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

39. Difficult ventilation
Difficult ventilation
The inability of a trained anesthetist to
The inability of a trained anesthetist to
maintain the oxygen saturation > 90% using
maintain the oxygen saturation > 90% using
a face mask for ventilation and 100%
a face mask for ventilation and 100%
inspired oxygen, provided that the pre-
inspired oxygen, provided that the pre-
ventilation oxygen saturation level was
ventilation oxygen saturation level was
within the normal range.
within the normal range.

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

41. Predictors of difficulty to face
Predictors of difficulty to face
mask ventilate (OBESE)
mask ventilate (OBESE)
1.
1.The
The O
Obese (body mass index > 26
bese (body mass index > 26
kg/m2)
kg/m2)
2.
2.The
The B
Bearded
earded
3.
3.The
The E
Elderly (older than 55 y)
lderly (older than 55 y)
4.
4.The
The S
Snorers
norers
5.
5.The
The E
Edentulous
dentulous

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

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

44. Wilson’s risk score
Wilson’s risk score
Score
Score
Weight
Weight 0=<90kg
0=<90kg
1=>90kg
1=>90kg
2=>110kg
2=>110kg
Head and
Head and
neck
neck
movement
movement
0=Above 90degrees
0=Above 90degrees
1=About 90degrees
1=About 90degrees
2=Below 90degrees
2=Below 90degrees
Jaw
Jaw
movement
movement
0=IG>5cm or SLux >0
0=IG>5cm or SLux >0
1=IG<5cm and SLux = 0
1=IG<5cm and SLux = 0
2=IG<5cm and SLux<0
2=IG<5cm and SLux<0
Receding
Receding
mandible
mandible
0=Normal
0=Normal
1=Moderate
1=Moderate
2=Severe
2=Severe
Buck teeth
Buck teeth 0=Normal
0=Normal
1=Moderate
1=Moderate
2=Severe
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.

45. MANAGEMENT PLAN
OF
ANTICIPATED
DIFFICULT AIRWAY
45

46. Intubation
Intubation
 Equipment
Equipment
– TRAINED ASSISTANT
TRAINED ASSISTANT
– Laryngoscopes with a selection of blades
Laryngoscopes with a selection of blades
– Variety of endotracheal tubes
Variety of endotracheal tubes
– Introducers for endotracheal tubes (stylets or flexible bougies)
Introducers for endotracheal tubes (stylets or flexible bougies)
– Oral and nasal airways
Oral and nasal airways
– A cricothyroid puncture kit
A cricothyroid puncture kit
– Reliable suction equipment
Reliable suction equipment
– Laryngeal mask airways, sizes 3 AND 4
Laryngeal mask airways, sizes 3 AND 4
 The safety of laryngoscopy can be increased by preoxygenating the patient prior to
The safety of laryngoscopy can be increased by preoxygenating the patient prior to
induction and attempts at intubation.
induction and attempts at intubation.
 Intubation is attempted by optimal direct laryngoscopy;
Intubation is attempted by optimal direct laryngoscopy;
– optimal head and neck positioning
optimal head and neck positioning
– optimal muscle relaxation
optimal muscle relaxation
– optimal laryngoscope blade
optimal laryngoscope blade
– optimal external laryngeal manipulation
optimal external laryngeal manipulation
– optimal use of the bougie
optimal use of the bougie
 After intubation correct placement of the tube should be confirmed by:
After intubation correct placement of the tube should be confirmed by:
– Observing the tube pass through the cords
Observing the tube pass through the cords
– Successful inflation of the chest on manual ventilation
Successful inflation of the chest on manual ventilation
– Auscultation over both lung fields in the axillae
Auscultation over both lung fields in the axillae
– Capnograph
Capnograph
– If in doubt – take it out
If in doubt – take it out

47. Consider the merits and feasibility
Awake Intubation vs Intubation after induction
of GA
Non-Invasive technique vs Invasive technique
for initial approach for initial approach
Preservation of spontaneous vs Ablation of spontaneous
Ventilation ventilation
47

48. What are we going to do if we don’t get the
Tube?
• Plans “A”, “B” and “C”
• Know this answer before you tube.

49. Plan “A”: (ALTERNATE)
• Different Length of blade
• Different Type of Blade
• Different Position

50. Plan “B”: (BVM and BLIND INTUBATION
Techniques )
• Can you Ventilate with a BVM? (Consider
two person mask Ventilation)
• Combi-Tube?
• LMA an Option?

51. What do we do when faced with a
Can’t Intubate Can’t Ventilate
situation?
• Plan “C”: (CRIC) Needle, Surgical,

52. 52
DIFFICULT AIRWAY MANAGEMENT:
DIFFICULT AIRWAY MANAGEMENT:
Can’t Intubate
Can’t Intubate
Retrograde Intubation

55. TFE catheter: prevent the ET tube form redundancy over
the guidewire  decrease trauma, increase success rate

58. References
References
 Practice guidelines for management of the difficult airway: an updated
Practice guidelines for management of the difficult airway: an updated
report by the American Society of Anesthesiologists Task Force on
report by the American Society of Anesthesiologists Task Force on
Management of the Difficult Airway. Anesthesiology 2003; 98 (5):1269-
Management of the Difficult Airway. Anesthesiology 2003; 98 (5):1269-
77
77
 Frerk CM. Predicting difficult intubation. Anaesthesia 1991; 46 (12):1005-
Frerk CM. Predicting difficult intubation. Anaesthesia 1991; 46 (12):1005-
8
8
 Verghese C, Brimacombe JR
Verghese C, Brimacombe JR. Survey of laryngeal mask airway usage in
. Survey of laryngeal mask airway usage in
11,910 patients: safety and efficacy for conventional and nonconventional
11,910 patients: safety and efficacy for conventional and nonconventional
usage. Anesth Analg 1996; 82: 129–33
usage. Anesth Analg 1996; 82: 129–33
 Gupta S, Sharma R, Jain D. Airway assessment – Predictors of a Difficult
Gupta S, Sharma R, Jain D. Airway assessment – Predictors of a Difficult
Airway. Indian Journal Of Anaesthetics 2005; 49(4) : 257 -262
Airway. Indian Journal Of Anaesthetics 2005; 49(4) : 257 -262
 Wilson M, Spiegelhalter D, Robertson A, Predicting difficult intubation.
Wilson M, Spiegelhalter D, Robertson A, Predicting difficult intubation.
Br. J. Anaesth.
Br. J. Anaesth. (1988), 61, 211-216
(1988), 61, 211-216
 The Difficult Airway Society Website:
The Difficult Airway Society Website: WWW.DAS.UK.COM
 Reed M, Dunn M, McKeown D. Can an an airway assessment score
Reed M, Dunn M, McKeown D. Can an an airway assessment score
predict difficulty at intubation in the emergency department. Emerg Med J
predict difficulty at intubation in the emergency department. Emerg Med J
2005;22:99–102.
2005;22:99–102.