Difficult Airway Management

Anesthesia Assistant Course

Algonquin College

Joel Berube

19 SEP 09

Objectives

Airway management is our specialty! Significant M&M associated with mismanaged

airways Avoidance:

Anticipate Airway exam, predictors of difficulties

Preparation Know your equipment

Back-up plan Methods, adjuncts for intubation/ventilation/oxygenation

Outline

The Difficult AirwayDefinitionsAssessment

The AlgorithmAnticipated DAUnanticipated DA

DevicesFibreoptic BronchGlidescopeBullard ScopeJet Ventilator

Surgical AirwaysPercutaneous TrachCricothyroidotomyTrans-tracheal Jet

The “Difficult Airway” Definitions

Difficult Airway

Difficult Laryngoscopy

Difficult Mask Ventilation

Difficult Endotracheal Intubation

Difficult Airway

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

Difficult Mask Ventilation

1 person unable to keep SpO2 >92%

Significant gas leak around face mask

No chest movement

Two-handed mask ventilation needed

Change of operator required

Use of fresh gas flow button >2X (flush)

Predictors of Difficult Ventilation

BeardHiding? Bad seal

ObesityBMI > 26

Age>55

TeethLack of…

SnoringOn history or dx OSA

BOATS

Difficult Laryngoscopy

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

Difficult Endotracheal Intubation

Insertion of ETT with direct laryngoscopy requires >3 attempts or >10 minutes

Or when an experienced laryngoscopist using direct laryngoscopy requires:More than 2 attempts with same bladeChange in blade or use of adjunctUse of alternative device/technique

following failed intubation with direct laryngoscope

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”?

Tough Airways?

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?

Difficult Airway Algorithm

A model for the approach to the difficult airway

Considers:Patient factorsClinical settingSkills of the practitioner

If you need to intubate the patient for the case and run into trouble at any step…

Airway assessment

Non-ReassuringLaryngoscopyVentilation techniqueAspiration RiskIntolerance of apnea

Anticipated DAAwake Technique

Box ANB - “Invasive” = knife

or needle in the neck (see “surgical airway”)

ReassuringPut the patient to

sleep, now having difficulty

Unanticipated DAAttempts after

inductionBox B

Difficult Airway Algorithm - Anticipated DA

DA anticipated, intubate Awake:

Patient will maintain their own patent airway

Can abandon or try another approachNo “bridges burned”

Concept: freeze the airway, put the tube in, +/- sedation (usually +!)

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!

Contraindications to Awake

Emergency: no ABSOLUTE, but cautionCardiac ischemia, bronchospasm,

increased ICP or ocular pressure

Elective:Refusal or inability to cooperate

Child, mental retardation, dementia, intox

Allergy to local anesthetics

Technique:

Generally “Awake Intubation” implies use of Fibreoptic Bronchoscope

Any other method to intubate is possible, but likely more difficult or tough to tolerateUsed to do awake blind nasal intubations in

trauma patients (some still do)

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 (<2mm ext diam)

Light Source

Bronch

FOB intubation:

BronchCorrect size

Light Source

monitor/eyepiece

Suction

O2 for patient

Tube/Lube

Oral Airways/Bite block

Local Anesthetic3 areas to freeze

NasopharynxBase of tongueLarynx/trachea

TopicalSwish/swallowPledgetsViscous

Nebulized4% Lido, 10-15min

pre

Nerve Blocks

FOB intubation

Topicalize the airwaySupplemental O2

Appropriate sedationFor the patient!

Insert Oral AirwayAppropriate size… it will

help guide scope and protect it

Tube loaded on scopeHolder/tapesuction

Visualize cords with scopeSome more local via

working channel?

Advance ETT Confirm placement

ETCO2

Induce the anestheticVery uncomfortable

Patient needs coaching/reassurance throughout!!!

Troubleshooting

FOB not good if pt. bleeding in A/W or ++ secretionsSuction not adequateTry O2 to clear lens

Desaturations…Keep O2 on!Breaks for patientSedation level

Fogging upDefoggerWarm scope prior to startingSuction/insuffl/flushAdjust picture?

Tube not advancing through cordsToo large tube and too

small scope: the extra room causes the tube to catch on arytenoids

Softer ETTDeep breathScope in centre of cords,

bevel forward, rotate ETT clockwise

Pearls:

DA Algorithm

Ok, so if you’re not reassured by the airway, intubate awake If not successful (box A)

Cancel/wake vs. invasive airway!!

What if the airway doesn’t look bad and you bang the patient off to sleep only to see this…

Obviously you can’t just stick the tube in! What now?

From this point on, consider:

Call for HelpAbsolutely!

Return to Spontaneous Ventilation If you can

Awakening the patient If you can

Cannot Intubate Scenario

Optimize position/scope etc…DO NOT persist with repeated attempts

at direct laryngoscopyEvidence that this approach leads to

complications (including death)

Return to Mask Ventilation, get SpO2 back up and try another techniqueGlidescope, Bullard, Bougie, Trachlite,

Intubating LMA, McCoy Blade…

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 whatever’s 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

Other devices

Reviewed last week?

Different laryngoscope bladesMAC, Miller, McCoy

Different introducersStylet, Bougie, Trachlite

“Supraglottic Devices”LMA, Proseal, Fastrach (ILMA)Combitube, King Airway, Cobra Airway

Glidescope

Video-assisted laryngoscopyVideo chip set at the end

of a “conventional-like” blade

Steeper angle (60º)

Canadian Invention!

Glidescope Advantages

Setup minimal/easy!

Handled with similar skills for direct laryngoscopyBut in midlineNo need to elevate tongue

Point of sight is near blade tipCan see around the corner”

Image on screenSupervisor, assistant

can see too

Less stress on airway

Don’t need external light sourceLightweight, compact

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!!!

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?

Bullard +’s

Low profileGets into mouth when opening limited

High Flow O2 via channel blows secretions away and may reduce fogging

Attached stylet helps direct tube to glottisCan use standard scope handle instead of

light source

Bullard -’s

Finnicky… sometimes very difficult to get a good view, even in an easy airway

Plastic extension on blade sometimes dislodges. Don’t forget it in the patient!!!

Back to the Difficult Airway

Still unable to intubate despite help, various adjuncts, adjustments, alternate devices…

Now you’re 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

Cannot Intubate-Cannot Ventilate

THIS IS AN EMERGENCY If you haven’t yet… CALL FOR HELP

People die if you can’t ventilate them

You NEED to secure an airway or have the patient awake and breathing on their own!Securing the airway likely now = Invasive AirwaySalvage techniques while getting the surgical

airway?

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 tracheaNeedle cricothyroidotomy and jet ventilationPercutaneous cricothyroidotomy setEmergency/Awake Tracheostomy

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

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

Sanders Jet Ventilation

O2 from hi-pressure source (50psi) thru valve and switch to a needle and into the airway

Used in shared airway surgeriesRigid bronch

Surgeon working in airway, can’t use normal ventilation/ETT

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

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

Emergency Tracheostomy

Rather than needling the neck, once it’s 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

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 Can’t intubate, can’t ventilate scenario is avoided!

Awake patient prepped and draped, surgery started… once airway access secured, induction of anesthesia can occur

Recap

Difficult Airway Definitions Predictors

Difficult Airway Algorithm Fibreoptic Bronchoscope

Awake intubation

Alternate Devices Glide, Bullard, Sanders

Emergency Airway Surgical Airway

Take-Home messages

Not all airways are routine There’s 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

Questions? Discussion?

Thank you.