The Difficult or Failed Airway

Pat Melanson, MD

The Difficult Airway

• Must be able to assess or anticipate the degree of difficulty

• Then select method most likely to succeed

• If properly assessed and felt to be intubatable without significant difficulty– 1-4 /1000 will be impossible intubations (O.R.)

– 1 / 280 obstetrical patients

– 1 /10,000 impossible to intubate or ventilate(O.R.)

– 1-2 % cricothyroidotomy rate in ED

Definitions• Failed intubation

– inability to place an ETT

• Difficult intubation– requires more than 3 attempts or 10 minutes

• Difficult laryngosopy– Cormack and Lehane grade III (epiglottis only) or

grade IV view (soft palate only)

• Difficult mask ventilation• Failed airway

– can’t intubate, can’t ventilate

The Difficult Airway: Necessary Skills

• Clinical Airway Assessment– ability to recognize/ predict Difficult Airway

• Facility with array of airway equipment– knowledge of indications and advantages – ability to choose most appropriate technique for

the particular situation– manual skills

• Detailed knowledge of intubation medications

The Difficult Airway

• Not all airway management failures are avoidable or predictable

• Attempt to minimize failures

• Have several definite back-up plans ready for the “Failed Airway”

Prediction of the Difficult Airway

• Historical features ( prior AW difficulty)– Anesthesia record in old chart– Medic alert bracelet– Cric or tracheotomy scar

• Anatomic features

Prediction of the Difficult Airway

• C-spine mobility

• External dimensions ( 3-3-2 rule)– Mouth opening 3 fingers (TMJ)– Mandible large enough to accommodate

tongue - 3 fingers from tip of chin to hyoid– Length of neck/position of larynx - 2 fingers

between top of thyroid and floor of jaw

Prediction of the Difficult Airway (con’t)

• Teeth– large or protruding incisors obstruct vision– jagged teeth can lacerate balloon

• Oral dimensions– narrow facial features and high arched

palates (decreased lateral space)– Mallimpadi classification

Mallimpadi Classification (Tongue to Pharyngeal Size)

• I - soft palate, uvula, tonsillar pillars visible– 99 % have grade I laryngoscopic view

• II - soft palate, uvula visible• III - soft palate, base of uvula• IV - soft palate not visible

– 100% grade III or grade IV views• *** this exam is seldom possible in an emergency situation

Predictors of Difficult Laryngoscopy

• Short,thick, muscular neck

• Receding mandible

• Protruding maxillary incisors– “Buck teeth”

• Poor TMJ mobility/ limited jaw opening

• Limited head and neck movement – ( including trauma )

• High, arched palate

Difficult Airway : Laryngoscopy

• Tumor, abscess or hematoma

• Burns

• Angioneurotic edema

• Blunt or penetrating trauma

• Rheumatoid arthritis, ankylosing spondylitis

• Congenital syndromes

• Neck surgery or radiation

Plan B : Response to Unanticipated

Difficulty

• Difficult laryngoscopy and intubation– Can’t intubate but Can ventilate– Can’t intubate and Can’t ventilate

• Difficult Mask Ventilation

Unsuccessful Intubation : Plan B• Bag the patient• Maximize neck flex/ head ex• Move tongue out of line of site• Maximize mouth opening• ID landmarks and adjust blade• BURP maneuver

– (Backwards Upwards Rightwards Pressure on Thyroid Cartilage)

• Increasing lifting force• Consider Miller blade• Bag the patient

Unsuccessful Intubation : Plan B

• An optimal or best attempt at difficult laryngoscopy should consist of :– use of optimal sniffing position– no significant muscle tone– use of optimum external laryngeal

manipulation (BURP)– one change in length of blade– one change in type of blade– a reasonably experienced laryngoscopist

Unsuccessful Intubation : Plan B

• Remember, the first response to failure to intubate should always be to Bag-Mask-Ventilate the patient

• The first response to failure of bag-mask-ventilation is always better bag-mask-ventilation

Algorithm for Difficulty “Bagging”

• Remove FB - Magill forceps

• Triple maneuver if c-spine clear

– Head tilt, jaw lift, mouth opening

• Nasal or oropharyngeal airways

• two-person, four-hand technique

• Do not abandon bagging unless it is impossible with two people and both an OP and NP airway

The Failed Intubation: Definition

• Three failed attempts to intubate– by an experienced intubator

• Inability to ventilate with BVM

• Inability to oxygenate

The Failed Intubation

• If can’t intubate but can ventilate with BVM have time to consider options– Light guided technique (Lighted stylet)– Combitube– LMA– Fiberoptic techniques– Retrograde intubation– Cricothyrotomy

The Failed Intubation

• If can’t intubate, can’t ventilate , must act immediately– Cricothyrotomy– Percutaneous Transtracheal Jet Ventilation– Combitube– LMA– The last three are temporizing measures and

not definitive airway management

Clinical Approach to the Difficult Airway

Is a difficult airway predicted?“nothing should be taken away from the

patient that the airway manager can’t replace”

Bag-Mask predicted to be successful? Intubation deemed reasonably likely ? Do I have the ability to rescue the airway

if “can’t intubate, can’t ventilate”?

Awake Oral Intubation

• Consider for anticipated can’t intubate, can’t ventilate situation

• distorted upper airway anatomy • (i.e., penetrating neck trauma)

• Avoids ‘burning bridges”• maintains ventilation • maintains patient’s ability to protect airway

• May use to take quick look to assure that you can see enough for RSI

Awake Oral Intubation

• Prepare patient psychologically

• Pre-oxygenate

• Topical anesthesia if time permits

• Titrated sedation - avoid obtundation

• Reassure patient throughout procedure

Difficult Airway Kit• Multiple blades and ETTs

• ETT guides (stylets, bougé, light wand)

• Emergency nonsurgical ventilation ( LMA, Combitube, TTJV )

• Emergency surgical airway access ( cricothyroidotomy kit, cricotomes )

• ETT placement verification

• Fiberoptic and retrograde intubation

Techniques for Difficult Intubation

• Alternative laryngoscope blades• Awake intubation• Blind oral or nasal intubation• Fiberoptic intubation• Gum Elastic Bougé• Light wand• Retrograde intubation• Surgical airway

Techniques for Difficult Ventilation

• Combitube

• Laryngeal Mask Airway

• Oral and nasopharyngeal airways

• Two person mask ventilation

• Transtracheal jet ventilation

• Surgical airway

Difficult Airway Maxims

• The first response to failure of Bag-Mask Ventilation is always better BVM– optimize airway position– place both OP and NP airways– two-handed, two-person technique – try lifting head off pillow to open airway– Generate as much positive pressure as

possible without inflating the stomach

Difficult Airway Maxims

• Use judicious sedation and topical airway anesthesia to have a quick look in doubtful cases

• In certain situations a paralytic agent and RSI may still be the best choice

Difficult Airway Maxims

• “It is preferable to use superior judgement -- to avoid having to use superior skill”.