Difficult Airway Management

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Difficult Airway Management

• Anesthesia Assistant Course
• Algonquin College
• Joel Berube
• 19 SEP 09

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Objectives

• Airway management is our specialty!
• Significant MM associated with mismanaged
  airways
• Avoidance
• Anticipate
• Airway exam, predictors of difficulties
• Preparation
• Know your equipment
• Back-up plan
• Methods, adjuncts for intubation/ventilation/oxyge
  nation

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Outline

• The Difficult Airway
• Definitions
• Assessment
• The Algorithm
• Anticipated DA
• Unanticipated DA

• Devices
• Fibreoptic Bronch
• Glidescope
• Bullard Scope
• Jet Ventilator
• Surgical Airways
• Percutaneous Trach
• Cricothyroidotomy
• Trans-tracheal Jet

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The Difficult Airway Definitions

• Difficult Airway
• Difficult Laryngoscopy

• Difficult Mask Ventilation
• Difficult Endotracheal Intubation

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Difficult Airway

• Situation where a conventionally trained
  anesthesiologist experiences difficulty with
  mask ventilation, endotracheal intubation or both

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Difficult Mask Ventilation

• 1 person unable to keep SpO2 gt92
• Significant gas leak around face mask
• No chest movement
• Two-handed mask ventilation needed
• Change of operator required
• Use of fresh gas flow button gt2X (flush)

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Predictors of Difficult Ventilation

• Beard
• Hiding? Bad seal
• Obesity
• BMI gt 26
• Age
• gt55
• Teeth
• Lack of
• Snoring
• On history or dx OSA

BOATS
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Difficult Laryngoscopy

• Not possible to view any part of the vocal cords
  during direct laryngoscopy
• Cormac-Lehane Grades III/IV

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Difficult Endotracheal Intubation

• Insertion of ETT with direct laryngoscopy
  requires gt3 attempts or gt10 minutes
• Or when an experienced laryngoscopist using
  direct laryngoscopy requires
• More than 2 attempts with same blade
• Change in blade or use of adjunct
• Use of alternative device/technique following
  failed intubation with direct laryngoscope

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Predictors of Difficult Laryngoscopy/Intubation

• aka your airway assessment (last class)
• Mallampati
• What can you see when they open their mouth?
• Mouth Opening, teeth
• Can you fit your blade tube in the opening?
• Thyromental Distance
• Predicts an anterior larynx
• C-Spine Range of Motion
• Can they get in a sniffing position?

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Tough Airways?
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General Approach to Airways

• Is Airway Control Required?
• ie is there a different anesthetic technique?
• Predict Difficult Laryngoscopy?
• Is Supralaryngeal Ventilation (LMA, mask) ok to
  use if needed?
• ie can you get away without intubation?
• Full Stomach?
• Will the patient tolerate an apneic period?

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Difficult Airway Algorithm

• A model for the approach to the difficult airway
• Considers
• Patient factors
• Clinical setting
• Skills of the practitioner
• If you need to intubate the patient for the case
  and run into trouble at any step

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Airway assessment

• Non-Reassuring
• Laryngoscopy
• Ventilation technique
• Aspiration Risk
• Intolerance of apnea
• Anticipated DA
• Awake Technique
• Box A
• NB - Invasive knife or needle in the neck
  (see surgical airway)

• Reassuring
• Put the patient to sleep, now having difficulty
• Unanticipated DA
• Attempts after induction
• Box B

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Difficult Airway Algorithm - Anticipated DA
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DA anticipated, intubate Awake

• Patient will maintain their own patent airway
• Can abandon or try another approach
• No bridges burned
• Concept freeze the airway, put the tube in, /-
  sedation (usually !)

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Awake Intubation Advantages

• Maintain spontaneous ventilation
• Wide open pharynx and palate space
• Forward tongue
• Maintain esophageal tone (?aspiration)
• Able to protect if reflux occurs
• Risk of neurologic injury able to monitor
  sensory-motor function
• Some spines awake intubation positioning!

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Contraindications to Awake

• Emergency no ABSOLUTE, but caution
• Cardiac ischemia, bronchospasm, increased ICP or
  ocular pressure
• Elective
• Refusal or inability to cooperate
• Child, mental retardation, dementia, intox
• Allergy to local anesthetics

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Technique

• Generally Awake Intubation implies use of
  Fibreoptic Bronchoscope
• Any other method to intubate is possible, but
  likely more difficult or tough to tolerate
• Used to do awake blind nasal intubations in
  trauma patients (some still do)

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The Fibreoptic Bronchoscope

• fragile device with optical and non-optical
  elements
• Glass-fibre bundle (10k-30k fibres)
• Objective - Insertion Cord - Eyepiece
• 60cm, graduated q10cm
• Flexible, rotate, bend, control
• Working Channel (2mm diam)
• Suction, O2, fluids, drugs
• Peds intubating scopes no channel (lt2mm ext
  diam)
• Light Source

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Bronch
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FOB intubation

• Local Anesthetic
• 3 areas to freeze
• Nasopharynx
• Base of tongue
• Larynx/trachea
• Topical
• Swish/swallow
• Pledgets
• Viscous
• Nebulized
• 4 Lido, 10-15min pre
• Nerve Blocks

• Bronch
• Correct size
• Light Source
• monitor/eyepiece
• Suction
• O2 for patient
• Tube/Lube
• Oral Airways/Bite block

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FOB intubation

• Topicalize the airway
• Supplemental O2
• Appropriate sedation
• For the patient!
• Insert Oral Airway
• Appropriate size it will help guide scope and
  protect it
• Tube loaded on scope
• Holder/tape
• suction

• Visualize cords with scope
• Some more local via working channel?
• Advance ETT
• Confirm placement
• ETCO2
• Induce the anesthetic
• Very uncomfortable

Patient needs coaching/reassurance throughout!!!
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Troubleshooting

• Tube not advancing through cords
• Too large tube and too small scope the extra
  room causes the tube to catch on arytenoids
• Softer ETT
• Deep breath
• Scope in centre of cords, bevel forward, rotate
  ETT clockwise

• FOB not good if pt. bleeding in A/W or
  secretions
• Suction not adequate
• Try O2 to clear lens
• Desaturations
• Keep O2 on!
• Breaks for patient
• Sedation level
• Fogging up
• Defogger
• Warm scope prior to starting
• Suction/insuffl/flush
• Adjust picture?

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Pearls
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DA Algorithm

• Ok, so if youre not reassured by the airway,
  intubate awake
• If not successful (box A)
• Cancel/wake vs. invasive airway!!
• What if the airway doesnt look bad and you bang
  the patient off to sleep only to see this

Obviously you cant just stick the tube in! What
now?
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From this point on, consider

• Call for Help
• Absolutely!
• Return to Spontaneous Ventilation
• If you can
• Awakening the patient
• If you can

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Cannot Intubate Scenario

• Optimize position/scope etc
• DO NOT persist with repeated attempts at direct
  laryngoscopy
• Evidence that this approach leads to
  complications (including death)
• Return to Mask Ventilation, get SpO2 back up and
  try another technique
• Glidescope, Bullard, Bougie, Trachlite,
  Intubating LMA, McCoy Blade

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Alternate Techniques

• Your first attempt at laryngoscopy should always
  be set up to be the best
• Early transition from one technique to another
  without persistent and multiple failed attempts
• On subsequent attempts, use adjuncts to enhance
  whatevers missing the last time
• Need to remain fluid/flexible and adapt the plan
  as you progress through the algorithm
• Often means going through lots of equipment
• Having backups and backups for the backups

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Other devices

• Reviewed last week?
• Different laryngoscope blades
• MAC, Miller, McCoy
• Different introducers
• Stylet, Bougie, Trachlite
• Supraglottic Devices
• LMA, Proseal, Fastrach (ILMA)
• Combitube, King Airway, Cobra Airway

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Glidescope

• Video-assisted laryngoscopy
• Video chip set at the end of a conventional-like
  blade
• Steeper angle (60º)

Canadian Invention!
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Glidescope Advantages

• Setup minimal/easy!
• Handled with similar skills for direct
  laryngoscopy
• But in midline
• No need to elevate tongue
• Point of sight is near blade tip
• Can see around the corner

• Image on screen
• Supervisor, assistant can see too
• Less stress on airway
• Dont need external light source
• Lightweight, compact

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Glidescope Negatives

• As with FOB, image can be obscured by
  blood/secretion
• Less a problem with color vs. B/W monitor
• Sometimes view is better than you can get a tube
  into
• Variations on stylet bends
• Re-usable glidescope stylet
• Limited number of handles/blades
• Need to be sterilized between uses
• Cap in correct place before cleaning!!!

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Bullard Scope

• Fixed fibreoptic cable on posterior part of blade
• Same setup as FOB
• Eyepiece
• Working Channel
• Detachable Stylet
• Blade has natural curve
• Good if C-spine ROM ?

Predecessor to Glidescope?
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Bullard s

• Low profile
• Gets into mouth when opening limited
• High Flow O2 via channel blows secretions away
  and may reduce fogging
• Attached stylet helps direct tube to glottis
• Can use standard scope handle instead of light
  source

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Bullard -s

• Finnicky sometimes very difficult to get a good
  view, even in an easy airway
• Plastic extension on blade sometimes dislodges.
  Dont forget it in the patient!!!

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Back to the Difficult Airway

• Still unable to intubate despite help, various
  adjuncts, adjustments, alternate devices
• Now youre having trouble ventilating!!!
• Now try 2 and 3 handed mask ventilation, LMA (if
  feasible)
• If this works, get the SpO2 back up, breathe
  yourself Try again, abort, discuss

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Cannot Intubate-Cannot Ventilate

• THIS IS AN EMERGENCY
• If you havent yet CALL FOR HELP
• People die if you cant ventilate them
• You NEED to secure an airway or have the patient
  awake and breathing on their own!
• Securing the airway likely now Invasive Airway
• Salvage techniques while getting the surgical
  airway?

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The Surgical Airway

• aka the invasive airway
• If access to the airway through the mouth or nose
  is unavailable, need to access the airway via the
  trachea
• Needle cricothyroidotomy and jet ventilation
• Percutaneous cricothyroidotomy set
• Emergency/Awake Tracheostomy

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Cricothyroidotomy

• Landmarks thyroid cartilage, cricoid cartilage
  cricothyroid membrane
• Local to skin (if time) and entry via membrane
  with large needle attached to partially-filled
  syringe
• Aspiration of air into airway!
• Proceed to ventilate, retrograde wire intubation,
  percutaneous cric set

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Transtracheal Ventilation

• Connect the needle/angiocath to an oxygen source,
  jet ventilator, ambubag and deliver air/oxygen
  into the trachea
• Not a protected or definitive airway
• Life-saving, temporizing measure

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Sanders Jet Ventilation

• O2 from hi-pressure source (50psi) thru valve and
  switch to a needle and into the airway
• Used in shared airway surgeries
• Rigid bronch

Surgeon working in airway, cant use normal
ventilation/ETT
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Sanders Jet Ventilator

• Continuous Ventilation is possible
• Can minimize apneic period, shorten surgery
• Can deliver O2, N2O, Volatile Anesthetic
• Jet entrains room air, so variable and
  unpredictable FiO2 at end of scope
• Inadequate ventilation of lungs if poor
  compliance
• Difficult to assess adequacy of ventilation
• Can be used for transtracheal oxygenation
• Next section

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Percutaneous Cric Set

• Once cricothyroid membrane punctured with needle,
  can use Seldinger technique to dilate tissues and
  insert a large bore cannula to secure the airway
• Not a trach, but allows ventilation and
  oxygenation with low-pressure systems (std 15mm
  connector)
• Ambubag, conventional ventilator
• Some are cuffed, so would protect airway

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Emergency Tracheostomy

• Rather than needling the neck, once its
  established that the patient needs a surgical
  airway, the surgeon performs a surgical
  tracheostomy
• Awake or asleep, depending on where on the
  algorithm the scenario happens to be

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Awake Tracheostomy

• Some airways are so non-reassuring and patients
  so high risk that Plan A is to perform a
  tracheostomy under local anesthetic (/- minimal
  sedation) PRIOR to any other airway management or
  anesthesia
• Ex certain head/neck tumors/malformations,
• Any attempt at awake intubation may create an A/W
  obstruction and loss of airway
• Cant intubate, cant ventilate scenario is
  avoided!
• Awake patient prepped and draped, surgery
  started once airway access secured, induction of
  anesthesia can occur

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Recap

• Difficult Airway Definitions
• Predictors
• Difficult Airway Algorithm
• Fibreoptic Bronchoscope
• Awake intubation
• Alternate Devices
• Glide, Bullard, Sanders
• Emergency Airway
• Surgical Airway

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Take-Home messages

• Not all airways are routine
• Theres more to a difficult airway than difficult
  laryngoscopy
• Need skills with various airway tools and
  adjuncts and must transition between them easily
  and quickly
• Familiarity with the difficult airway algorithm
  should give you a sense of which direction a
  given scenario is taking
• When faced with cannot intubate, cannot ventilate
  scenario, decision to secure surgical airway is
  life-saving and hesitation can be costly

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Questions? Discussion?

• Thank you.