Management of Difficult Airway in Anesthesia Part I

1
Management of Difficult Airway in
AnesthesiaPart I

• Chan Wei-Hung MD
• Department of Anesthesiology
• National Taiwan University Hospital

2
Difficult Airway in Anesthesia Practice

• Inability to maintain airways explains more than
  30 of death in anesthesia.
• More than 85 in respiratory-related malpractice
  would lead to severe brain damage or death.

3
Difficult Airway

• Anticipated
• Unanticipated
• How to evaluate the difficult airway?
• Evaluation for Difficult Intubation
• Evaluation for Difficult Mask Ventilation

4
Evaluation for Difficult Intubation

• Mallampati test
• Thyromental distance
• Mouth opening
• C-spine mobility
• Dentition
• Difficult recognition of cricothyroid membrane

5
Mallampati Test
Class I
Class II
Class III
Class IV
6
How to Do Mallampati Test

• Patient remains seated.
• Ask the patient to open the mouth as widely as
  possible and protrude tongue as far out as
  possible.
• Phonation should not be encouraged.
• Perform the test twice to avoid bias.

7
Validity of the Test (I)
Cormack Grade of Laryngoscopic View
8
Validity of the Test (II)
Cormack Grade Cormack Grade Cormack Grade Cormack Grade
Gr. 1 Gr. 2 Gr. 3 Gr.4
Class 1 (73.8) 59.5 14.3 0 0
Class 2 (19) 5.7 6.7 4.7 1.9
Class 3 (7.14) 0 0.5 4.3 2.4
Mallampati class
Total 210 patients
9
(No Transcript)
10
Difficult Mask Ventilation

• Facial deformity (congenital, acquired)
• Geriatric patients with depressed cheeks
• Patients with a nasogastric tube
• Extremely fat patients
• Patients with head fixation devices
• Patients with long mustache
• High risk of aspiration
• Patients with orofacial burn
• Patients with extremely limited mouth
  openingDifficulty in inserting an oropharyngeal
  airway

11
Pathological Conditions Associated with Difficult
Airway

• Infection
• Trauma
• C-spine injury
• Obesity
• DM
• Acromegaly
• Foreign body

• Ankylosing spondylitis
• Rheumatoid arthritis
• Tumors
• Congenital syndromes
• Pregnancy

12
The ENT Cases

• Always check the chart for visibility of vocal
  cord.
• In case of airway tumors/abscess, search for
  CT/MRI images for the position and the width of
  the airway.

13
Rheumatoid Arthritis

• TMJ ankylosis, limitation of motion of the
  cervical spine, deviation of the
  larynx,cricoarytenoid arthritis
• Laryngeal involvement--edematous, hyperemic
  cords, arytenoid mucosa with swollen
  aryepiglottic folds and false cords
• A smaller ET tube may be necessary.

14
DM Difficult Airway (I)

• Severe diabetes mellitus can result in abnormal
  cross-linkage of collagen by non-enzymatic
  glycosylation in connective tissues due to
  chronic hyperglycemia.
• These tissues then become stiff and may result in
  limited joint mobility (stiff joint syndrome).
• Prayer sign

15
DM Difficult Airway (II)

• 32 of 115 diabetic patients who underwent renal
  and/or pancreatic transplant had a difficult
  laryngoscopy
• Difficult laryngoscopy in 31 of 62 diabetic
  patients undergoing renal transplantation or
  vitrectomy.
• Of 725 transplant patients, diabetic vs
  non-diabetic 4.8 vs 1.0 were identified as
  having difficult laryngoscopies, but no
  extraordinary devices were required for
  intubation.

Anesth Analg 1988671162-5
Anaesthesia 1990451024-7
Anesthesia Analgesia. 86516-9, 1998
16
Palm Print as a Predictor of Difficult Airway in
DM
Acta Anaesthesiologica Scandinavica.
42(2)199-203, 1998
17
Sensitivity Specificity False-negative False-positive
Palm print gradegt0 1.00 0.57 0 26
Mallampati gt1 0.41 0.80 13 12
Mallampati gt2 0.50 0.98 21 1
TMD lt6 cm 0.14 0.9 19 6
Head extensionlt35 0.50 0.70 11 18
BMI gt 27 0.23 0.97 17 2
DM gt 10 yrs 0.91 0.67 2 20
DM type 0.45 0.51 12 30
Acta Anaesthesiologica Scandinavica.
42(2)199-203, 1998
18
Decision Making in Anticipated Difficult Airway
(I)

• All-or-none gambling ? how could you take the
  risk?
• The anesthesiologists always walk on a tightrope
  between becoming a hero or being bankrupted.
• An outcome-based question
• Personal experience and preference is supremely
  important and govern the outcome.

19
Decision Making in Anticipated Difficult Airway
(II)

• The only universal rule and the No.1 guideline

Do not ever try to use anything that you are not
familiar with or any fancy equipment in such a
situation!
So be well-prepared for such a hard time!
20
Annual Meeting of ASA (American Society of
Anesthesiologists)

• Held in mid-October every year
• There always be a workshop for airway management,
  which is deserved to attend during residency.
• The 2002 Annual Meeting will be in Orlando,
  Florida on October 12-16, 2002.

http//www.asahq.org/
21
(No Transcript)
22
(No Transcript)
23
Decision Making in Anticipated Difficult Airway
(III)

• No matter where you practice, something you
  must know before you make decision
• What kind of equipment do you have at hand?
• What is the quality of the equipment?
• Do you have any assistant? (mask ventilation)
• How much does your assistant know?
• Do you have immediate access to the help from
  your fellow anesthesiologists?
• What is the attitude of the surgeons?

24
Decision Making in Anticipated Difficult Airway
(IV)
Anticipated Difficult Airway
Difficult Mask Ventilation
YES
NO
Awake Intubation
Induction Procedures
25
Succinylcholine Friend or Foe?

• Rapid onset, short duration always welcomed.
• Undeniable weak points
• Fatal hyperkalemia (burn, spinal cord injury)
• Malignant hyperthermia
• Masseter spasm
• Atypical plasma cholinesterase

26
SCC vs Vecuronium
In 44 pediatric patients, the mouth opening by mm

Before After Before After
16.92.8 12.64.3 19.83.6 20.94.1
Succinylcholine
Vecuronium
Mouth opening was measured by a constant force
(1.4N).
Anesthesiology 69(1)11-6, 1988
27
Mivacurium or Rocuronium Destined to Be Ousted?

• Low dose ? slow onset
• High dose ? long duration

• For Rocuronium
• 11.2 mg/kg IV bolus
• Onset 45 sec
• Duration 30 min

For Mivacurium 0.20.25 mg/kg IV bolus Onset 2
min Duration 515 min
28
The Prolonged Duration of Rocuronium (0.6 mg/kg)
in Chinese Patients
Anesthesia Analgesia 91(6)1526-30, 2000
29
Mivacurium Rocuronium
Onset (sec) Duration (min) Recovery Index (min)
SCC 1mg/kg 55.1 4.2 1.3
Mi 0.2 mg/kg 116 10.4 4.2
Ro 0.6mg/kg 97.9 23.7 9.2
Ro 0.9 mg/kg 70.5 36.4 10.1
Mi 0.1 mg/kg Ro 0.3 mg/kg 67 15.2 7.3
Mi 0.15 mg/kg Ro 0.45 m/kg 55 25.3 9.9
British Journal of Anaesthesia 79(4)450-5, 1997
30
Preoxygenation How Much Is Enough?

• Two techniques common in use
• Tidal volume breathing (TVB) of oxygen for 35
  min
• Deep breaths (DB) 4 times within 0.5 min
• Both are equally effective in increasing
  arterial oxygen tension (Pao2).

Anesth Analg 1981 60 3135
31
Anesth Analg 2001 92 1337-1341
32
After preoxygenation to an end-tidal oxygen
concentration greater than 90, each subject
received 5 mg/kg thiopental and 1 mg/kg
succinylcholine.
Anesthesiology 2001, 95 754-759
Succinylcholine itself cannot save your account.
(Esp. when you did not do good preoxygenation.)
33
Who is at the risk of premature desaturation?

• Obesity
• Parturient
• Neonate
• Decreased FRC

34
Other Weak Points of Pentothal SCC

• Copious secretion after awaking the patient,
  hampering subsequent fiberoscope.
• It is said that with this technique a period of
  inadequate ventilation would happen during
  recovery.

Pentothal SCC then take a look is generally a
good idea, but it does not guarantee anything!
35
All the Toys You Know How to Play

• No 1 rule
• Do not stick to the same one too long.
• No 2 rule
• Always be doing something.

36
Equipment Ready to Use

• Direct laryngoscope
• Think more about the laryngoscopy
• Patient position
• Smaller ET tube size
• Different blades
• Make good use of the stylet
• External laryngeal pressure
• If you can visualize epiglottis and make sure the
  midline position, you can give it a try
  otherwise give it up immediately.

37
External Laryngeal Pressure
38
Other Techniques

• Light wand
• Laryngeal mask airway
• Combitube
• Wus scope
• Cuffed oropharyngeal airway (COPA)
• Awake the patient

39
Endpoint of All Techniques

• Cant intubate, cant ventilate
• Establish airway through cricothyroid membrane
  immediately

Easier said than done. Not every cricithyroid
membrane is easily recognized. (Especially on
your first time, perhaps the last time, too) Try
to define it on a fat man with a short neck.
Remember to hyperextend the neck.
40
Cricothyroid Membrane Puncture

• You wont need to do so for too many times in
  life.
• However, you must know how to do it.

41
On Hand Technique

• Use big-bore cath-over-needle (14 or 16)
• Attach syringe at the end of the cath, keep
  gentle negative pressure
• Puncture caudally until air is withdraw from the
  syringe
• Advance needle a little bit with extreme care
  (much like the way in vascular access)
• Hold the needle and advance the cath
• Remove needle, attach syringe to the hub of the
  cath, aspirate air to ascertain its correct
  position.

42
Three Ways to Go

• Transtracheal jet ventilation (TTJV)
• Connect to a traditional ventilator
• Commercial cricothyrotomy kit

43
Transtracheal Jet Ventilation

• This can be delivered directly through the cath
  or (if you have the time) insert a single-lumen
  CVP catheter by Seldinger technique.
• Drawbacks
• Not always available
• High risk of complication (barotrauma)
• Angiocath is prone to kinking
• Problem shooting attach a syringe and aspirate
  air to test (kinking, subcutaneous penetration)
  auscultation

44
Transtracheal Jet Ventilation

• Because of drastic outcome with its complication,
  you must be very alert all the time when using
  TTJV. (Complication may occur even when you think
  Im safe now.)
• So when TTJV is working well, dont just go away
  try some other thing like fiberoptic intubation /
  call ENT doctor for tracheostomy immediately!!

45
Settings of TTJV

• Driving pressure 50 psi (20-50 have been
  proposed as acceptable)
• IE ratio 113
• Rate 1020/min
• Higher frequency (100600/min) is for those who
  have compromised pulmonary function (improving
  oxygenation along with less barotrauma compared
  with conventional positive pressure ventilation).

46
Recovery from TTJV

• Bucking and glottic closure during TTJV may
  increase the risk of barotrauma, esp. when
  short-duration agent (like SCC) is used.
• Monitoring EMG at forearm is not practical
  (laryngeal and diaphragmatic muscles are more
  resistant to muscle relaxants.) airway pressure
  tracing was proposed for monitoring.
• Pay heed to patients movement oral suction
  regularly while hold TTJV momentarily.

47
Pros and Cons of TTJV

• Simpler, quicker, less training required compared
  with ciricothyrotomy
• With poor patency of upper airway, gas exhalation
  can be hindered and lung hyper-expansion ensues ?
  increased risk for barotrauma

Insert an artificial airway when using TTJV.
Decrease the I/E ratio (longer expiration). Use
in long procedures is not favored.
48
Connect to a Traditional Ventilator

• Unorthodox method not generally accepted, better
  than nothing
• Connect the hub of the cath to the ventilator via
  a 3 mm ET tube adaptor.
• Connect the hub of the cath to a 5-ml syringe
  then insert a 7.0 mm ET tube inside, inflate the
  cuff, then connect to the ventilator.
• Connect the hub of the cath to a 3-ml syringe
  then insert an adaptor form a 7.5 mm ET tube
  inside, then connect to the ventilator

49
(No Transcript)
50
Connect to a Traditional Ventilator

• Higher respiratory pressure required (mimic
  TTJV).? use O2 flush button.
• Self-inflated reservoir bag can be used as well.

51
(No Transcript)
52
Connect to a Traditional Ventilator

• Problem with the method high pressure is mostly
  absorbed by corrugated connection tubing.
• Pressure limit in some anesthesia machine models

53
Commercial Cricothyrotomy Kit

• If you are familiar with this kit, I suggest you
  try it first.
• Use Seldinger technique or knife cutting
• Direct connection to ventilator

54
(No Transcript)
55
(No Transcript)
56
(No Transcript)
57
(No Transcript)
58
(No Transcript)
59
(No Transcript)
60
(No Transcript)
61
(No Transcript)
62
Decision Making in Anticipated Difficult Airway
(IV)
Anticipated Difficult Airway
Difficult Mask Ventilation
YES
NO
Awake Intubation
Induction Procedures
63
Awake Intubation

• Take a look with laryngoscope
• Oral/Nasal fiberoptic intubation
• Retrograde intubation

64
Retrograde Intubation

• Usually not for emergent conditions
  (time-consuming)
• Puncture site should be close to cricoid
  cartilage.
• A smaller ET tube may be easier to slide into the
  trachea.
• Do check the position of the tube before you put
  the patient into sleep. (ET-CO2!!)
• The combination with fiberoscope is desirable.

65
Retrograde Intubation Risks and
Contraindications

• Contraindications
• Ongoing coagulopathy
• Obscure cricothyroid anatomy
• Infection of the cricothyroid membrane
• Neck mass (i.e. goiter)
• Risks
• bleeding in the airway
• ET tube may not pass easily into the larynx.

66
(No Transcript)
67
(No Transcript)
68
(No Transcript)
69
TFE catheter prevent the ET tube form redundancy
over the guidewire ? decrease trauma, increase
success rate
70
(No Transcript)
71
(No Transcript)
72
Retrograde Intubation with the Aid of Fiberoscope

1. Guidewire goes through Murphy eye fiberoscope
   goes through main lumen.
2. Thread guidewire through the suction lumen of the
   fiberoscope.

OR
73
Highlights for Part II

• Lightwand intubation
• Laryngeal mask airway
• Awake fiberoptic intubation
• ASA algorithm for difficult airway
• Exclusion of Esophageal Intubation