Airway Anatomy and Airway Management Flashcards
3 paired cartilages of larynx
arytenoids
corniculates
cuneiforms
What is the Mallampati Classification?
Correlates the oropharyngeal space with the ease of direct laryngoscopy and tracheal intubation
hypothesis: when the base of the tongue is disproportionately large, the tongue overshadows the larynx resulting in difficult exposure of the vocal cords during laryngoscopy
components of laryngopharynx
tip of epiglottis to cricoid cartilage
Innervation of nasal passages
Branches of the trigeminal nerve (CN V)
How do you assess the Mallampati Score?
Pt sitting upright, head neutral, mouth open as wide as possible and tongue maximally protruded. No AAAAHH!
Innervation of anterior 2/3 tongue
Trigeminal nerve (CN V)
Compare and contrast the right and left bronchus.
Right bronchus is short and fat (2.5 cm long) with an angle of 25°
Left bronchus is long and skinny (5 cm long) with an angle of 45º
Discuss the disadvantes of using an LMA.
- NOT a definitive airway
- lower seal pressure
- higher frequency of gastric insufflation
- esophageal reflux more likely
-
inability to use mechanical ventilation
- **patient should be spontaneously breathing**
- CANNOT use NMBD (neuromuscular blockade)
Should use an oral airway for a patient that is semi conscious?
Why or why not?
No, oral airways are not well tolerated in awake or moderately awake patients. The patient should be “deep.”
Complications can include:
- laryngospasm
- bleeding
- soft tissue dammage
Function of the arytenoid muscles. Are they intrinsic or extrinsic laryngeal muscles?
intrinsic laryngeal muscle
oblique arytenoids and transverse arytenoids
Adduct the vocal cords also
What is the greatest predictor of a difficult airway?
“No single test has been devised to predict a difficult aiway accurately 100% of the time”
*previous difficult intubation should always raise suspicion*
**It is not one factor but a combination oof factors that create the difficult airway**
Questions/factors to consider for airway assessment.
Radiation or burn to head/neck
body builder or large body habitus - neck > 40 cm
C spine pain or LROM
TMJ pain
Rheumatoid arthritis
abscess or tumor
prior intubation or tracheostomy (old trach scar?)
snoring or sleep apnea
dysphagia, stridor, hoarse voice quality
ankylosing spondylitis
components of oropharynx
begins at base of uvula, tonsils, ends at epiglottis
What is the ideal postion for placement of ETT?
4 cm above the carina and 2 cm below the vocal cords
Males: approximately 23 cm
Females: approximately 21 cm
If unsure (peds population): ID (internal diameter) x3
i.e. 4.0 mm = 12 cm
How do you measure for proper sizing of an oral airway?
Center of the mouth to the angle of the jaw
OR
Corner of the mouth to the ear lobe
Vocal cords: appearance, formation, attachments
appear pearly white
formed by the thyroartyenoid ligaments
attached anteriorly to the thyroid cartilage and posteriorly to the arytenoid cartilages
Function of thyroarytenoid muscle
intrinsic laryngeal muscle
relaxes/shortens vocal cords
“they relax”
What components of the laryngoscope handle and blade need to be checked before use?
Handles - check the battery!
Blades - check the light! (to see if it’s working AND to make sure the light bulb is tight so it does not fall into the patient’s airway!)
Connect handle and blade to ensure proper fit and working
Want one of each macintosh and miller blade for set up
Describe the classes of the mandibular protrusion test and the significance of each class.
How do we ALWAYS check for proper placment of our ETT?
- bilateral breath sounds
- bilateral chest rise
- presence of end-tital CO2
- note fogging breaths in tube
General Anesthesia - Mask Case: When do we use?
- Difficult airway not present
- Surgeon does not need access to head/neck
- No airway bleeding/secretions
- Case of short duration
- No table position changes - head available
- Obstruction easily relieved with oral nasal airway/chin lift
- Patient will spontaneously breathe - no neuromuscular blocker used
What is a Laryngeal Mask Airway (LMA) and what is it used for?
- supraglottic airway device
- used for routine AND difficult airway managment
- can be used as a conduit for ETT placement
- appropriate size is based on patient weight
- adult sizes
- 30-50 kg → LMA 3
- 50-70 kg → LMA 4
- 70-100 kg → LMA 5
- >100 kg → LMA 6
- adult sizes
Innervation of soft palate (mostly uvula)
glossopharyngeal nerve (CN IX)
Considerations/complications for a nasal trumpet.
Is the patient on anticoagulation?
epistaxis
nasal or basal skull fractures
adenoid hypertrophy
Where are the intrinsic laryngeal muscles?
At the glottic opening
Components of lower airway
trachea
carina
brochi
bronchioles
terminal bronchioles
respiratory bronchioles
alveoli
Hard and soft palate innervation
trigeminal nerve (CN V)
What are the corniculates? Where are they located?
paired cartilages
posterior portion of the aryepiglottic fold
Arytenoids
paired cartilages
attach directly to the cricoid cartilage
posterior attachment for vocal cords
*falsely identified in an anterior airway*
3 unpaired cartilages of larynx
thyroid
cricoid
epiglottis
In the oral cavity, the trigeminal nerve (CN V), innervates which structures?
hard and soft palate
anterior 2/3 tongue
Placement of fingers on the soft tissues of the neck while masking can occlude the airway of which population?
Pediatric population
Cormack and Lehane Score: Grade II
only the posterior portion of the glottis visible
All intrinsic muscles, except for the cricothyroid muscle, are innervated by the _____ ______ ______, a branch of the ______ ______.
recurrent laryngeal nerve; vagus nerve
Cuneiforms
paired cartilages
lateral to corniculates in the aryepiglottic fold, not always present
Describe the technique for masking
Hold mask in left and resevoir bag in right.
Put thumb on upper aspect of the the mask, index and middle fingers on lower aspect, and 4th/5th fingers under chin for chin lift/jaw thrust.
*Try to keep fingers on bridge of the jaw bone, not soft tissue*
Vocalis muscles
intrinsic laryngeal muscle
ALSO relaxes/shortens vocal cords
Who should get an airway assessment?
EVERYONE
regardless of whether you work with the for 5 minutes or >12 hours.
regardless of types of procedure taking place.
Cormack and Lehane Score: Grade I
Most of the glottis visible
During mask ventilation, if we cannot achieve adequate tidal volumes at < 20 cm H2O, what kinds of things should we assess?
Airway patency
Pulmonary compliance
components of nasopharynx
starts posterior to turbinates, includes adenoids, stops at base of uvula
How can we measure the effectiveness of our mask ventialtion?
chest rise
exhaled tidal volumes
pulse oximetry - readings and sound
capnography - ETCO2
What happens to the trachea at the carina?
Divides the trachea into right and left mainstem bronchi.
INFO CARD
Various ETT options
- Double Lumen ETT
- Lung isolation - deflate right, ventilate left(vice versa)
- Tubes with place for nerve monitoring
- could be used in thyroid surgery
When is the best time to try a new airway technique?
Novel techniques for difficult AW management must be learned and practiced in a controlled environment with non-challenging airways.
***AN EMERGENCY IS NOT THE TIME TO A TRY A NEW TECHNIQUE***
Mallampati Class I
Generally associated with easy intubation.
“Think “P.U.S.H.”
Pillars, Uvula, Soft Palate, Hard Palate
faucial pillars, entire uvula, soft and hard palates
Mallampati Class II
Base of Uvula tip masked by tongue, uvula tip masked by tongue
Soft and Hard palates
Function of the Posterior Cricoarytenoid
intrinsic laryngeal muscle
The only vocal cord ABductors
“Please come apart”
Mallampati Class IV
Hard palate only
What are the turbinates?
hard ridges of cartilage bottom turbinate is a bone in itself
What is the larynx?
complex structure of cartilage, muscles, and ligaments that serves as the inlet to the trachea and anterior commisure
Describe the anatomy of the trachea: length, diameter, structure
fibromuscular tube
10 - 20 cm length; 22 mm diameter (adult)
16-20 U shaped cartilages (posterior side lacks cartilage, its just muscle posteriorly)
Types of LMAs: Classic vs Supreme LMA
Supreme and ProSeal LMA can tolerate PPV up to 30 cm H2O
Potential difficulty with intubation/Predictors of difficult laryngoscopy.
- long upper incisors
- prominent overbite
- inaiblity to protrude mandible
- small mouth opening
- Mallampati class III or IV
- high, arched palate
- short thyromental distance
- short, thick neck
- limited cervical mobility
Discuss the advantages of using an LMA.
- increased speed and ease of placement by inexperienced personnel - questionable?
- improved hemodynamic stability at induction and during emergence
- reduced anesthetic requirements for airway tolerance
- lower frequency of coughing during emergence
- lower incidence of sore throats in adults (10% to 30%)
- avoids “foreign body” in the trachea
If we don’t have 3-5 minutes to pre-oxygenate, like in an emergency, what do we do?
4 vital capacity breaths within 30 seconds with 100% FiO2 at >6L/min
**Equal to 5 minutes of safe apnea time**
True or false: head straps can cause potential nerve injuries.
True
Can also be difficult for patients with claustrophobia
Where does the trachea birfuctate?
The carina @ T4
Proper/improper placement of an oral airway
Where are the turbinates?
nasal passages
Function of Crycothyroid muscle
intrinsic laryngeal muscle
tenses/elongates vocal cords
“cords tense”
Absolute indications and “other” indications for use of ETT.
-
Absolute indications
- full stomach
- high risk for aspiration of gastric secretions or blood
- critically ill
- significant lung abnormalities (i.e. low lung compliance, high airway resistance, impaired oxygenation)
- surgery requiring lung isolation
- otorhinolaryngologic surgery (ENT, head/neck) where an SGA would interfere with surgical access (AW managment discussed with surgeon)
- anticipated need for post-operative ventilatory support
- failed SGA placement
-
Others
- surgical requirement for NMBDs (neuromuscular blockade)
- positioning that does not allow quick access ot the AW (i.e. prone)
- predicted difficult airway
- prolonged procedures
Function of Lateral Cricoarytenoids
intrinsic laryngeal muscle
Adducts the vocal cords
“Lets close the airway”
(From the book) The pharyngeal musculature in the awake patient helps maintain airway patency; loss of pharyngeal muscle tone is one of the primary causes of_______ ________ __________ during anesthesia.
upper airway obstruction
The space between the vocal cords is termed the ________.
glottis (book p 1378)
True or False: the internal laryngeal nerve, of the superior laryngeal nerve is purely sensory.
True.
the external laryngeal nerve is motor and innervates the cricothyroid muscle.
Conerstone: ASA Difficult AW Algorithm
How do you measure proper sizing for a nasal airway?
Length - estimated as distance from nares to meatus of ear
Diameter - french sizes 24, 26….36
Cormack and Lehane Score: Grade III
Only epiglottis visible
What is the “Murphy’s eye” of an ETT?
Additional distal opening in the side wall of the ETT
back - up portal for ventilation should the distal end of the lumen become obstructed by either soft tissue or secretions
Function of nasal passages
heats, humidifies, and filters air
(air becomes “turbinate”—>creates non linear flow, which is what heats up air)
accounts for 2/3 total upper airway resistance
Describe the differences between the laryngoscope handles discussed.
In a general overview of the ASA Difficult AW Algorithm: if we can mask ventilate our patient, do we have an emergency on our hands?
No, if you can successfully mask ventilate your patient, you have time to decipher what is the problem, and try interventions, as long as you can continue to mask ventilate if interventions don’t work.
The second you can no longer mask ventilate, you have an emergency.
You would then condsider SGA.
If SGA unsuccessful→EMERGENCY (may consider surgical airway)
List the potential hazards to airway management.
- dental damage
- soft tissue/mechanical injury (i.e. bleeding)
- laryngospasm
- bronchospasm
- vomiting/aspiration
- hypoxemia/hypercarbia
- esophageal/endobronchial intubation
- SNS stimulation
- Intubating is the most stimulating stimulus you can do to the human body/more stimulating than surgery
Innervation of posterior 1/3 tongue
glossopharyngeal nerve (CN IX)
Obesity and the “sniffing” position - Tips/factors to consider
Gold standard for AW management.
Endotracheal Tube
General Anesthesia - LMA Case: When do we use?
- Difficult airway not present
- Surgeon does not need access to head/neck
- No airway bleeding/secretions
- Case of short duration
- More reliable patent airway than mask
- Want hands free
Innervation of oropharynx
glossopharyngeal nerve (CN IX)
INFO CARD
Visual steps of LMA insertion.
Cormack and Lehane Score: Grade IV
No airway structures visualized, no visualization of epiglottis or larynx
Distinguish between a MAC blade and a Miller blade.
- MAC - Mactinosh
- sizing (1-4)
- Curved
- Miller
- sizing (0-4)
- straight
Name the two types of oral airways. Describe the difference in shapes and sizes.
Berman (BOA) and Guedel
Guedel has a hollow center - passageway for suction catheter if necessary
Berman (BOA) - solid, no passageway for catheter
Adult sizes:
small BOA (80 mm) = Guedel #3
medium BOA (90 mm) = Guedel #4
large BOA (100 mm) = Guedel #5
How do we accomplish pre oxygenation?
3-5 minutes of “tight” mask during normal tidal breathing with 100% FiO2 at > 6L/min flow
**This will equal 10 minutes of safe apnea time**
Epiglottis
unpaired cartilage
covers opening to the larynx during swallowing
Laryngospcopic view of the epiglottis
Functions of larynx
airway protection (with epiglottis)
respiration
phonation (with air passing through vocal cords)
How do you mask ventialte someone if the masking requires you to use both hands?
Utilize a resource in the OR to squeeze the bag to ventialte while you hold the mask in place with both hands.
Discuss the intubation technique and how technique differs between using a MAC or Miller blade.
- A great time to test out using a miller blade is with an edentulous patient
When the pharyngeal tonsils become inflamed, they are referred to as?
Adenoids
Visual steps of proper insertion of nasal airway. INFO CARD.
Describe the components of an airway set up.
- Appropriate sized face mask
- means of PPV - ambu bag, machine circuit
- suction ON and easily accessible
- Tongue depressor - aids with oral airway insertion
- appropriate sized oral and nasal airways
- laryngoscope handle
- 2 different blades
- Endotracheal tube (ETT) - 2 sizes, appropriate size + 1/2 to full size smaller
- stylet
- syringe
- appropriate sized laryngeal mask airway (LMA) - (either planned airway for case or difficult airway adjunct) - this is a supraglottic airway
- tape
What is the goal of pre oxygenation?
Increase O2 concentration in functional residual capacity (FRC - volume of air left in the lung at end of passive expiration) by “washing out” nitrogen (79% in RA) in the FRC with oxygen.
Mallampati Class III
Soft and Hard palates only
uvula base only
Why do we use mask ventilation?
Preoxygentaion for induction
Post induction
Comonents of visual/physical airway assessment.
- general appearance
- head, neck size and fullness
- visual inspection of face
- obvious facial deformities
- neoplasms involving face of neck
- large goiter
- short or thick neck > 40 cm
- range of motion
- dentition
- loose teeth
- edentulousness (easier to mask, more difficult to intubate)
- veneers, caps, corwns, and bridges (particularly susceptible to damage)
- mouth
- tongue, lips, tissues, gums/bleeding or friable tissue
- large tongue/macroglossia
- high arched palate
- mouth opening
- (30-40 mm or 2-3 fingers)
- body habitus
- pregnancy, large breasts
- distribution of body habitus
- Mallampati Classification
- Thyromental Distance
- Mandibular Protrusion Test
- Diagnosis
- Planned surgery
What is a “MAC” case?
Monitored Anesthesia Care
- complete airway set up and ready to go
- nasal cannula - EVERYONE GETS O2
- spontaneously breathing patient
- nasal airway if snoring (partially obstructed breathing)
Where is the larynx located in regard to the spine?
C4-C6 in the adult
Additional SGA options
What is a stylet and how do we use it optimally?
- helps to add rigidity to ETT
- can use malleable stylet to hockey stick shape
- 60 degree angle formed 4 - 5 cm from distal end
- removed when the tip of the ETT is right at the level of the vocal cords
- limits trauma to tracheal mucosa
- **have someone help you remove stylet as you are still becoming comfortable with managing intubation**
Which component of the mouth is the predominate cause of airway resistance in the oral cavity?
tongue
Cricoid cartilage
unpaired cartilage
only complete cartilaginous, signet - shaped, ring
**narrowest portion of the pediatric airway**
Describe the proper way to open a mouth before inserting the blade.
- The scissors technique
- Should feel the jaw pop when opened
List and discuss the common features of an ETT.
-
standard 15 mm adaptor
- **common place of disconnect, needs tightening**
-
high volume, low pressure cuff
- purpose: creates a seal to protect against gastric aspiration
- ensures tidal volume delivered reaches the lungs
- design decreases necrotic tissue occurence
-
Pilot balloon with one-way valve
- needed for cuff inflation & assessment of cuff pressure
- minimal inflation volume to attain air leak
- ~20 - 25 cm H2O
What is the pharynx?
A muscular tube that extends from the base of the skull down to the level of the cricoid cartilage and connects the nasal and oral cavities with the larynx and esophagus.
Components of nasal passage anatomy
septum
turbinates
adenoids
Discuss the uses for a nasal airway/nasal trumpet.
- Used to provide passageway, nose pharynx, beneath the relaxed and obstructing tongue
- Used in series (small to large) to dilate prior to elective nasal intubation
- Usually tolerated better than oral airway during light anesthesia/possibly during emergence
Components of oral cavity anatomy
teeth
tongue
hard palate
soft palate
Suprahyoid group of extrinsic laryngeal muscles
raise larynx cephalad (or up towards the head)
General Anesthesia - Tracheal Intubation: When do we use?
- Airway compromise
- Airway inaccessible
- Long surgical time
- Alternate surgical positions
- Surgery of head, neck, chest, or abdomen
- Need for controlled ventilation and/or PEEP
- Inability to maintain airway with mask/LMA
- Aspiration risk
- Airway/lung disease
- Surgery requiring NMBD/muscle relaxation
In general, which size ETTs should we use for adult males and females?
*Want TWO sizes available*
Female: 6.5-7.0 mm id (internal diameter)
Male: 7.5-8.0 mm id (internal diameter)
*Consideration: if patient is planned to go back to ICU and remain intubated, consider larger ETT (8.0) for both males and females, unless notably small*
A common problem during induction of anesthesia is airway obstruction by the ______ and ______ due to relaxation of the ____________ muscle.
tonge; epiglottis; genioglossus
Thyroid cartilage location and description
unpaired cartilage
large and most prominent
anterior attachment for vocal cords.
For mask ventilation, adequate tidal volumes should be achieved with peak inspiratory pressures less than ____ cm H2O. Why should we avoid higher pressures?
20 cm H2O
Closing the APL (adjustable pressure limiting) to achieve higher volumes may be indicative of an airway obstruction (possibly the tongue).
*Note: higher pressures don’t necessarilly push air into the lungs, but rather into the stomach → causing gastric insufflation→putting the patient at higher risk for aspiration.*
Infrahyoid group of extrinsic laryngeal muscles
moves larynx caudad (or down)
A chin lift with mouth closure increases longitudinal tension in the _________ muscles, counteracting the the tendency of the _________ airway to collapse.
pharyngeal; pharyngeal
Describe the glottic opening
opening leading to trachea
triangular fissure between the cords
**in the adult, narrowest portion of the airway**
Describe the Cormack and Lehane Score
The laryngospic view of the glottis.
The Mallampati class is correlated to what can be seen on direct laryngoscopy.
Grade I: most of the glottis visible
Grade II: Only the posterior portion of the glottis visible
Grade III: Only epiglottis visible
Grade IV: No airway structures visualized
Describe thyromental distance
Distance from lower border of mandible to thyroid notch with neck fully extended
Normal: 6-6.5 cm or 4 fingerbeadths (fingerbreadths can be too variable based on the size of the hand of the provider)
Difficult intubation with < 3 fingers
- receding mandible or reduced mandibular space
- angle of intubation is more difficult
- termed “anterior larynx” or “anterior airway” (not actually more anterior to the skin, actually more chephalad, or closer to the head)
Two attachment points for vocal cords: anterior and posterior.
anterior: thyroid cartilage
posterior: arytenoids
Describe the innervation of the cricothyroid muscle.
Innervated by the external branch of the superior laryngeal nerve, a branch of the Vagus nerve (CN X)
Describe the mnemonic for preparing for induction.
Monitors on and settings appropriate (VS alarms appropriate, always have beep associated with pulse and sat probe so you can monitor for changes immediately)
Suction ON and at head of bed (ON + continuous + HOB)
Machine checked, means of positive pressure ventilation - ambu bag ALWAYS
Airway - complete airway set up (multiple ETTs-one of same size and half size smaller, LMA, oral airway, nasal airway, laryngoscope handle, multiple laryngoscope blades)
IV access, 1 or 2 sufficient working IVs, blood tubing? fluid warmer?
Drugs (emergency and case/patient specific)
Special equipment (i.e. positioning aids)
Equipment needed and steps of LMA insertion.
-
Equipment
- 20 or 50 cc syringe
- lubricant, suction, stehoscope, tape
- **lubricate posterior/top side only**
- if lubricated on bottom, lube can fall on to vocal cords, causing laryngospasm
-
Steps of Insertion
- position head - neck flexed and head extended
- Hold LMA with right hand like a pen with black line facing you
- Insert LUBRICATED LMA into mouth, follow palate centrally, push into oropharynx until resistance is felt, and then stop.
- Release right hand, grasp upper aspect of LMA, and attempt further advancement of the LMA
- Inflate cuff (LMA will move)
- Ventilate - observe, listen (stomach, lungs)
- secure with tape
Function of extrinsic laryngeal muscles
move larynx up or down as a whole
List some predictors of difficult mask ventilation.
- OSA or hx of snoring
- age >55 years
- male
- BMI > or = 30 kg/m2
- Mallampati class III or IV
- presence of a beard
- edentulousness
3 components of upper airway (pharynx)
nasopharynx
oropharynx
hypopharynx/laryngopharynx
*upper airway connects the nasal and oral cavities to the larynx and esophagus*
Describe the optimal intubating position.
- “Sniffing” position - aligns the 3 axis
- oral axis
- pharyngeal axis
- laryngeal axis
- provides the most optimal visualization of the vocal cords
- allows for the most effective mask ventilation
- positioning is key for success
- ESPECIALLY FOR THE NOVICE PRACTITIONER
Function of the intrinsic laryngeal muscles
control the movements of the laryngeal cartilages
control the length and tension of the vocal cords and the size of the glottic opening
Anatomy of the larynx
In the oral cavity, the glossopharyngeal nerve (CN IX) innervates which 3 structures?
posterior 1/3 tongue
soft palate (mostly uvula)
oropharynx
What are some patient characteristics that may predicult a difficult anesthetic mask fit?
beard
edentulous (no teeth) - easy intubation, difficult masking
short mandible
How do you assess a Mandibular Protrusion Test?
- Ask patient to bite their upper lip
- Class A:
- if they can, they have good mandibular protrusion, and you will be able to push their chin forward with a the blade (ability to jaw thrust)
- Class B and C
- associated with difficult laryngoscopy
- Class A:
