American Society of Anesthesiologists Difficult Airway Algorithm Feb, 2013

1. Evidence Based
Medicine
“Practical Guidelines for Management of
the Difficult Airway”

2. Practical Guidelines
Practice guidelines are systematically
developed recommendations that assist
practitioner and patient in making
decisions about health care.
American Society of Anesthesiologists
Anesthesiology 2013 (February); 118:251-70

3. Definitions
Difficult Airway:
The clinical situation in which a
conventionally trained anesthesiologist
experiences difficulty with facemask
ventilation of the upper airway, difficulty
with tracheal intubation or both

4. Sub Definitions
1. Difficult facemask or supraglottic
airway (SGA):
Difficulty in providing ventilation because
of one or more problems.
 Inadequate mask or SGA seal
 Excessive gas leak
 Excessive resistance to ingress or egress of air

5. Sub Definitions
2. Difficult SGA placement:
Requires multiple attempts, in presence
or absence of tracheal pathology
3. Difficult Laryngoscopy:
Not possible to visualise any portion of
the vocal cords after multiple attempts at
conventional laryngoscopy

6. Sub Definitions
4. Difficult Tracheal intubation:
Requiring multiple attempts in the
presence or absence of tracheal pathology
5. Failed intubation:
Placement of ETT fails after multiple
attempts.

7. Availability & Strength of
Evidence

8. CATEGORY ‘A’
Level ‘1’ : Sufficient number of RCTs to conduct
meta-analysis and meta-analytic findings
Level ‘2’ : Number of RCTs is insufficient to
conduct viable meta-analysis
Level ‘3’ : Single RCT

9. CATEGORY ‘B’
Level ‘1’ : Observational comparisons between
clinical interventions for a specified outcome
Level ‘2’ : Observational studies with associative
statistics (relative risk, correlations)
Level ‘3’ : Noncomparative observational studies
with descriptive statistics
(frequencies, percentages)
Level ‘4’ : Case reports

10. Inferred findings are given a directional
designation of:
Beneficial (B)
Harmful (H)
Equivocal (E)

11. GUIDELINES

12. STEP 1:
Evalution of the Airway

13. 1. Evalution of the Airway
History:
• Association between several characters
(age, obesity, OSA, H/O snoring) and difficult
laryngoscopy (B2—H)
• Difficult intubation or extubation in patients with
mediastinal masses (B3—H)
• Difficult laryngoscopy or intubation in variety of disease
states e.g; ankylosis, tonsillar
hypertrophy, osteoarthritis, pierre robin. (B4—H)

14. 1. Evalution of the Airway
Physical Examination:
• Association between anatomical features like features of
head and neck and likelihood of difficult airway
(B2—H)
• Radiography, CT scans, fluroscopy can identify variety of
acquired and congenital features in patients with difficult
airways (B3—B)

15. 1. Evalution of the Airway
Recommendations:
1. An airway history should be conducted with the intent to
detect medical, surgical and anesthetic factors that may
indicate presence of a difficult airway.
2. An airway physical examination should be conducted
with the intent to detect physical characteristics leading
to difficult airway.

16. 1. Evalution of the Airway

17. STEP 2:
The Basic Preparation

18. 2. Basic Preparation
• Preanesthetic preoxygenation by mask maintains higher
O2 saturation values compared with room air controls
(A3—B)
• 3mins preoxygenation maintains higher oxygen
saturation values compared to 1min preoxygenation
(A2—B)

19. 2. Basic Preparation
• Oxygen saturation levels after preoxygenation are
equivocal in preoxygenation for 3mins and fast track
preoxygenation of 4 VC breaths in 30mins (A1—E)
• Lower frequencies of arterial desaturation during
transport with supplemental oxygen to PACU than
without oxygen (A1—B)

20. 2. Basic Preparation
Recommendations:
1. Inform the patient of special risks and procedures
pertaining management of difficult airway.
2. Atleast one additional assistant should immediately be
available to serve.
3. Always administer facemask preoxygenation.
4. Actively pursueopprtunities to deliver supplemental
oxygen throughout the process.
5. Atleast one portable specialised unit for difficult airway
management should be readily available.

21. 2. Basic Preparation

22. STEP 3:
Strategy for Intubation

23. 3. Strategy for Intubation
• A preplanned preinduction strategy should always be
planned for every anesthetic.
“Non invasive interventions”
a. Awake intubation
b. Video assisted laryngoscopy
c. Intubating stylets or tube changers
d. SGA for ventilation (LMA, Laryngeal tube)
e. SGA for intubation (ILMA)
f. Rigid larynogscopes
g. Fiberoptic guided intubations
h. Light wands

24. 3. Strategy for Intubation
• Awake fiberoptic intubation is successful in 88-100%
difficult airway cases (B3—B)
• Higher frequency of first attempt intubations with video
assisted laryngoscope (A1—B)
• No time differences between VAL and conventional
laryngoscopes (A1—E)
• No differences in degree of cervical spine deviation
between VAL and conventional laryngoscopes
(A3—B)

25. 3. Strategy for Intubation
• LMA providing rescue ventilation in 94.1% who cannot
be mask ventilated or intubated (B3—B)
• Laryngeal tubes provide adequate ventilation for 95% of
patients with pharyngeal and laryngeal tumors
(B4—B)
• When ILMA was used with semirigid collar, 3 of 10
patients were successfully intubated (B3—B)
• Higher first attempt intubation for fibreoptic ILMA than
standard fibreoptic intubation (A2—B)

26. 3. Strategy for Intubation
• Laryngoscopes of alternate design may improve glottis
visualisation (B3—B)
• Equivocal findings with rigid fiberscopes and rigid direct
laryngoscopy for successful intubation and time to
intubate (A2—E)
• ETCO2 confirms tracheal intubation in 88.5-100%
patients (B3—B)

27. 3. Strategy for Intubation
Recommendations:
1. Assessment of the likelihood and anticipated clinical
impact of six basic problems.
a. Difficulty with uncooperative patient
b. Difficult mask ventilation
c. Difficult SGA placement
d. Difficult laryngoscopy
e. Difficult Intubation
f. Difficult surgical airway access

28. 3. Strategy for Intubation
2. Consideration of the relative clinical merits and feasibility
of four basic choices:
a. Awake vs Intubation after GA
b. Noninvasive vs Invasive techniques
c. VAL as initial approach to intubation
d. Preservation vs Ablation of spontaneous ventilation
3. Confirmation of tracheal intubation using capnography is
mandatory requirement.

29. 3. Strategy for Intubation

30. STEP 4:
Strategy for Extubation

31. 4. Strategy for Extubation
Recommendations:
1. Consider merits of awake extubation vs extubation
before return of consciousness.
2. An airway management plan should be implemented if
the patient is unable to maintain ventilation.
3. Short term use of intubating bougie can serve as a
guide for expedited reintubation

32. 4. Strategy for Extubation
Criteria for Awake Extubation
Subjective:
1. Following commands
2. No blood/secretions in hypopharynx
3. Intact gag reflex
4. Headlift/tongue blade for 5sec
5. Adequate pain relief
6. Minimal end tidal conc. of inhaled anesthetics

33. 4. Strategy for Extubation
Criteria for Awake Extubation
Objective:
1. Vital Capacity >10ml/kg
2. Tidal volume > 6ml/kg
3. Inspiratory intrathoracic pressure >
-20cm H2O
4. Train of four T1/T4 > 0.7
5. Sustained tetanic contraction for 5sec
6. Alveolar to arterial PaO2 difference < 350mm
Hg

34. STEP 5:
Follow-up Care

35. 5. Follow-up Care
Recommendations:
1. A detailed description of the airway difficulties
encountered.
2. A detailed description of the various airway
management techniques used and indicate
whether they played beneficial and detrimental
role.

36. THE ALGORITHM

38. THANK YOU