1. The ASA Difficult Airway Algorithm: New Thoughts and Considerations
Chen, Chien-Yu
June 8, 2001

2. Introduction and Recognition Of A Difficult Airway
ASA difficult airway algorithm
( from Anesthesiology 1993, 1996)
Pre-op airway evaluation:
The more predictors used, the better the prediction

3. Recognized Unrecognized
Awake intubation
choices
LMA
Combitube
TTJV
Mask
ventilation
Intubation
Choices
Intubation
Choices

4. Pre-op airway evaluation (1)
No equipment,noninvasive, less than 1 min
1.Teeth
2. Inside of the month
3. Mandibular space
4. Neck

6. Pre-op airway evaluation (2)
Usually it is the combination of findings that determines the index of suspicion of airway difficulty
Pathological state
( cancer, infection, bleeding, disruption)
Bread
Obesity
Large breast

7. Recognized difficult airway- awake limb of algorithm (1)
Difficult airway (DA)
Awake Intubation

8. Recognized difficult airway- awake limb of algorithm (2)
Proper preparation is the most important determination of the success of an awake intubation
Psychological support
Use of drying agent
Titrated sedation
Vasoconstriction
Nerve block

9. Recognized difficult airway- awake limb of algorithm (3)
Very occasionally awake intubation may fail due to either lack of p’t cooperation, equipment and operator limitation
Fail of awake intubate:
Re-prepare
Cancel the op GA
Regional anesthesia
Surgical airway

10. Recognized difficult airway- awake limb of algorithm (4)
Surgical airway first choice
Laryngeal/ tracheal disruption
Upper airway abscess
Mandibular-maxillary fracture

11. Recognized difficult airway- awake limb of algorithm (5)
Use of regional anesthesia in a patient with a known difficult airway requires a high degree of judgment

13. Unrecognized difficult airway (1)
Mask ventilation  nonemergency pathway
考慮是否使用conventional laryngoscopy
 缺點: edema, bleeding
 惡化mask ventilation and intubation
 CVCI
 Plan B

14. Unrecognized difficult airway (2)
Definition of optimal intubation attempt
reasonably experienced endoscopist: 2-3 yrs
no significant muscle tone
optimal sniff position
optimal external laryngeal pressure
change length of blade*1
change type of blade*1

15. Unrecognized difficult airway (3)
Macintosh blade--
small narrow month, palate, oropharynx
Miller blade--
small mandibular space, large incisors, long floppy epiglottis

16. Unrecognized difficult airway (4)
DA 又可定義 laryngoscope use
> 3 attempts and/or > 10 min
Laryngoscope fail 後的choices
 fiberoptic intubation, LMA, airway intubator
 mask ventilation
 awaken or surgical airway

17. CVCI (1) 2 persons effort: Better mask seal Jaw thrust
Better tidal volume
Large oral pharyngeal, nasopharyngeal airways

19. CVCI (2)
The decision to abandon mask ventilation should be made after the anesthesiologist has made an optimal/best attempt at mask ventilation

20. CVCI (3) 8.5 min fully preoxygenated, p‘t 也會hypoxemic, dead
給1mg/kg SCC, 50% recovery
P’t will die before SCC wear off
awaken option  mg/kg

22. CVCI (4) LMA or Combitube-- conduit for fiberscope
work as ventilatory mechanism
few complications
inserted blindly, quickly, low level of skill
can’t solve glottic, subglottic problems
TTJV--
barotrauma