Airway Flashcards
Nasal Passages
- Septum
- Turbinates
- Adenoids
Nasal Passages Functions
- 2/3 of total upper airway resistance
- Humidify
- filter
- warm
Nasal Passage Innervation
Branches of Trigeminal nerve (CN 5)
Oral Cavity
- Teeth
- Tongue (main cause of airway resistance in oral cavity)
- Hard Palate
- Soft Palate (velum palatinum)
- a fibromuscular fold of tissue attached to the hard palate, forms the posterior one third
Oral Cavity Innervations
- Trigeminal Nerve (CN 5)
- hard and soft palate
- anterior 2/3 tongue - Glossopharyngeal (CN IX)
- posterior 1/3 of tongue
- soft palate
- oropharynx
Upper Airway
Pharynx (connects the nasal and oral cavities)
- nasopharynx
- oropharynx
- hypopharynx/ laryngopharynx
nasopharynx
borders soft palate
oropharynx
- border is the epiglottis
- tonsils
- uvula
hypopharynx/ laryngopharynx
leading up to glottic opening
Upper airway innervation
- glossopharyngeal (CN IX)
- vagus (CN X)
pharyngeal musculature
in the awake patient helps maintain airway patency; loss of pharyngeal muscle tone is one of the primary causes of upper airway obstruction during anesthesia
supraglottic
above the epiglottis
Larynx
- inlet to trachea
- cartilaginous framework of the larynx is made up of nine separate cartilage (3 paired 3 unpaired)
- C4-C6
Larynx Function
- Airway protection
- Respiration
- Phonation (speaking)
Epiglottis
cartilage flap that serves as the anterior border of the laryngeal inlet.
Epiglottis Function
divert food away from the larynx during the act of swallowing
Larynx
nine separate cartilages:
unpaired
- epiglottis
- thyroid
- cricoid (only complete ring)
- narrowest point in pedi airway
paired
- arytenoid
- corniculate
- cuneiform
Cricothyroid ligament
ligament in-between thyroid cartilage and cricoid cartilage
Thyroid Cartilage
- large and most prominent
- anterior attachment for vocal cords
Cricoid Cartilage
- only complete cartilage ring
- narrowest point in pedi airway
Arytenoid
- posterior attachment for vocal cords
* falsely identified in anterior airways
Corniculate
-posterior portion of aryepiglottic fold
Cuneiform
- lateral to corniculates (in the aryepiglottic fold)
* not always present
Vocal cords
- within your larynx
- pearly white
- formed by thyroarytenoid ligaments
- connected anteriorly to the thyroid cartilage and posteriorly to the arytenoid cartilage
Glottic opening
- within larynx
- triangular fissure (space) between vocal cords
- narrowest spot of adult airway
Vestibule
-portion of the laryngeal cavity above the glottis
Subglottis
-portion below vocal cords
Laryngeal Muscles that help with Glottic opening (intrinsic)
- Lateral Cricoarytenoid
- Arytenoid Muscles
- Posterior Cricoarytenoid
Lateral Cricoarytenoid
Let airway Close
adducts vocal cords
Arytenoid Muscles
- oblique and transverse
- adduct the vocal cords
Posterior Cricoarytenoid
Pull Cord apart
-only vocal cord abductors
Laryngeal Muscles that help with Vocal cord length (intrinsic)
- Cricothyroid (tenses, elongates vocal cords)
- Thyroartyenoid (relies, shortens vocal cords)
- Vocalis (relaxes, shortens vocal cords)
Superior Laryngeal Nerve (intrinsic)
-branch of the VAGUS nerve
(CN X)
-external branch innervates cricothyroid muscle (tenses, elongates vocal cords)
Recurrent Laryngeal Nerve
intrinsic
- branch of VAGUS nerve (CN X)
- innervates all laryngeal muscles
- EXCEPT cricothyroid (innervated by external branch of superior laryngeal nerve)
Vagus Nerve
- cranial nerve X (parasympathetic control)
- Right and Left superior laryngeal nerve
- R and L recurrent laryngeal nerve
Extrinsic Laryngeal Muscles
- move larynx as a whole
- suprahyoid group
- infrahyoid group
Suprahyoid group
-extrinsic laryngeal muscles
- stylohoid
- mylohyoid
- geniohyoid
- digastric
Infrahyoid group
-extrinsic laryngeal muscles
- sternohyoid
- sternothyroid
- thyrohyoid
- omohyoid
Lower airway
- trachea
- carina
- bronchi
- bronchioles
- terminal bronchioles
- respiratory bronchioles
- alveoli
Trachea
- part of lower airway
- fibromuscular tube
- begins cricoid cartilage and extends to the carina (10-20 cm length and 22mm diameter )
- bifurcates carina -T4
- 16 to 20 C-shaped/ U-shaped cartilage rings
- posterior side open/ lacks cartilage
Carina
- part of lower airway
- where trachea ends and bifurcates into the right and left mainstem bronchi.
- R bronchi 2.5 cm long 25 degree angle
- L bronchi 5 cm and 45 degree angle
Airway assessment tests
- Mallampati classification (4 classifications PUSH, assess if tongue will overshadow larynx, done with head neutral, mouth open, tongue protruded, no phonation)
- Thyromental distance (distance from chin to thyroid cartilage with neck fully extended)
- Mandibular protrusione test
(do lower teeth protrude past upper) - Upper Lip Bite Test (can you bit your lip with your lower teeth)
MSMAIDS
-preparing for induction
M: monitors with correct settings
S: suction on @ head of bed
M: machine checked, PPV
A: airway (pre-oxygenate everyone)
I: iv
D: drugs emergency and case specific)
S: special equipment
Preoxygentation
- replacing nitrogen in lungs with oxygen
- increase 02 concentration in FRC (volume of air left in lungs after passive expiration) air is 79% Nitrogen
- 3-5 min of tight mask fit during normal tidal breathing with 100% Fi02 at >6L/min flow = 10 min of safe apnea time
- 4 vital capacity breaths with 100% at >6L/min within 30 seconds = 5 minutes
- 8 “ “ within 60 seconds > effectiveness (exceptions apply)
Aspiration
Loss of airway reflex
-high risk : full stomach, GERD, hiatal hernia, NG tube, obesity, pregnancy, diabetic gastroparesis
gastric prophylaxis
decrease gastric volume and increase gastric pH
Airway setup
- right size face mask
- PPV (bag, machine circuit, 02)
- suction on AND within reach
- tongue depressor
- oral and nasal airways
- laryngoscope handle
- blades (mac and miller)
- ETT 2 sizes
- stylet
- syringe
- LMA (sized based on weight)
- tape
maC blade
curved blade and inserted into the vallecula (usually size 3)
- most commonly used
- considered less likely to cause dental damage
predictors for difficult mask ventilation
- OSA/ snoring
- > 55 yr old
- Male
- BMI of 30 kg/m2 or greater
- Mallampati 3 or 4
- Beard
- Edentulousness
Mask Ventilation
- chest rise
- exhaled tidal volume (adequate volumes with PIP less than 20, don’t want to inflate stomach)
- pulse ox
- capnography
Upper airway obstruction
- usually occurs at soft palate, epiglottis and tongue
-reposition ( jaw thrust: extension and and forward displacement)
(sniffing position: cervical flexion and head extension)
-oral/ nasal airways
Oral airways
2 types
- berman (BOA)
- Guedel
Nasal airway
- used (in series) to dilate prior to elective nasal intubation
- tolerated better than oral airway in light anesthesia cases
- bevel facing nasal septum
- septum defects are common in adults, assess most patient care during prep assessment
- improper place meant can lead to avulsion or turbinate
Contraindicated: nasal, basal skull or cervical fracture
Laryngospasm
- caused by glossopharyngeal or vagal stimulation (from airway equipment or blood/ vomit)
- treat by removing irritant, deepening sedation, NMBD
- other tx CPAP or pressure at laryngospasm notch
Bronchospasm
- irritation of lower airway that activated a vagal reflex
- constriction of bronchiole smooth muscle
- untreated = inability to ventilate r/t increased airway resistance
- tx: increase sedation (propofol), inhaled B2 agonist / anticholinergic
Potential difficult intubation
- long upper incisors/ overbite
- small mouth opening
- Mallampati class 3 and 4
- high arched palate
- short thyromental distance (less than 3 fingers)
- short thick neck (>17cm)
- limited neck ROM
tracheal intubation
ETT inserted through glottic opening into trachea
miLLer blade
- straight blade
(usually rise 2)
-preferred on pt with short thyrometnal distance, and floppier airways (kids)
Murphy eye
- additional distal opening on ETT
- backup vent port should the distal end get obstructed
ETT
- high volume low pressure cuff (created seal to protect from aspiration)
- don’t overinflated cuff (4-5 cc) should have air leak at 20-25cm H20 (monitor cuff pressure with pressure gauge)
- cuff pressure can result in mucosal injury, vocal cord dysfunction, recurrent laryngeal nerve paralysis
N20 effect on ETT cuff
-when N20 is used in anesthetic it can diffuse into ETT cuff and increase cuff pressure
ETT sizing
-size based on internal diameter (ID)
- F: 6.5-7mm
- M: 7.5-8mm
ETT position
-4 cm above the carina 2 cm below vocal cords
- F: 21 cm
- M: 23 cm
ID x3
-tape to fixed pt (maxilla)
stylet
-helps shape tube into “hockey stick shape” (60 degree angle 4-5 cm from end)
**remove stylet when tip of ETT is at the level of the vocal cords
sniffing position
35 degree of cervical flexion and 7-9cm head elevation
- aligns 3 axis
- oral
- pharyngeal
- laryngeal
-optimal view of vocal cords, most effective mask ventilation
LMA
- supraglottic airway (above vocal cords)
- sizing based on weight
- must have bite block
LMA size
30-50 kg —- LMA 3
50-70kg —– LMA 4
70-100kg —- LMA 5
>100kg ——- LMA 6
LMA insertion
- 20-50 cc syringe
- bite block
- cuff pressure 40-60 cm H20
- audible leak at 18-20 cm H20
LMA advantages
- increased speed and ease of placement
- decrease needs of anesthetic and muscular relaxation
- lower frequency of coughing
- lower incidence of sore throat
- no “foreign body” in trachea
- improved hemodynamic stability at induction and emergencies
LMA disadvantages
- Not a definitive airway
- don’t have full protection from aspiration
- increased gastric insufflation (air in stomach)
- smaller seal pressure, ineffective ventilation when higher airway pressures needed
- No protection for laryngospasm
