Airway

Question 1

Parts of the Upper Airway?

Answer 1

1. Nasal passages
2. Oral cavity
3. Pharynx

Question 2

Parts of the pharynx

Answer 2

posterior nose to cricoid cartilage
nasopharynx- ends at the soft palate
Oropharynx- tonsils uvula and epiglottis
Laryngopharynx end of the oropharynx to the larynx

Question 3

What is the larynx and its functions?

Answer 3

at the level of C3-C6 in the adult
Epiglottis to the cricoid cartilage
contains epiglottis and the vocal cords.
3 functions: 1. airway protection 2. Respiration 3. Phonation
Consists of muscles, ligaments, and the vocal cords.
Contains the triangular fissure between the vocal cords known as the glottic opening (6-9mm.
Contains 3 paired and 3 unpaired cartilages

Question 4

Describe the cartilages of the larynx.

Answer 4

3 paired and 3 unpaired cartilages w/3 functions: adduct, abduct, regulate tension/ lengthen and shorten
Paired: arytenoid, corniculate, cuneiform
Unpaired: epiglottis, cricoid cartilage, thyroid cartilage

Question 5

Describe the paired cartilages and their functions

Answer 5

Arytenoids- serve as posterior attachment for the vocal cords (with an anterior airway may be only thing visible)
Corniculate and cuneiform- do not play a prominent role in laryngoscopic appearance or function

Question 6

Describe the paired cartilages and their functions

Answer 6

1. Thyroid cartilage
   housing/shield of the cords
   anterior attachment of the VC
2. Epiglottis
   protective, covers larynx during swallowing
3. Cricoid
   signet ring, narrowest of pediatric airway, inferior to thyroid membrane and forms the cricoid thyroid membrane

Question 7

What is the function of the laryngeal muscles.

Answer 7

Intrinsic muscles: moving the laryngeal parts, alters length and tension of the VC, size and shape
Extrinsic muscles- move the larynx as a whole (4 of them)

Question 8

What are the innervations of the intrinsic muscles of the larynx?

Answer 8

all innervated by the RLN a branch of the VAGUS (X), except the cricothyroid muscles: external branch of the SLN.

Question 9

What laryngeal muscles open and close the glottis?

Answer 9

1. Posterior cricoarytenoids- only VC ABDuctor
2. Arytenoids
3. Lateral cricoarytenoids
   RLN is responsible for innervating these

Question 10

What laryngeal muscles put tension on the vocal cords:

Answer 10

1. Cricothyroid
external branch of SLN
function is to elongate
2. Vocalis- shortens 
3. Thyroarytenoids- shortens and relaxes

Question 11

What are the 4 extrinsic muscles and their functions?

Answer 11

Moves the larynx as a whole “TOS”

1. Thyrohyoid, 2. Omohyoid, 3. Sternohyoid move they hyoid bone CAUDAD
2. Sternothyroid- moves the thyroid cartilage CAUDAD

Question 12

What are the parts of the lower airway

Answer 12

Trachea, carina, bronchi, bronchioles, terminal bronchioles, respiratory bronchioles, alveoli

Question 13

Describe the components of the trachea

Answer 13

Fibromuscular tube 10-20 cm in length and 22 cm diameter in the adult. 16-20 U shaped cartilaginous rings, posterior side lacks cartilage.
Bifurcates at the lower border of T4, known as the carina.
Carina: trachea deviates into R/L mainstem bronchus
R angle 25 degrees and 2.5 cm long
L angle is 45 degrees and 5 cm long
*impt to know because the anatomy favors a R angle intubation, could have VQ mismatch.

Question 14

Describe one’s airway evaluation.

Answer 14

It is not one factor but a combination of factors that creates a difficult airway. Systematic assessment and physical exam should be performed during the prep period.
1. evaluate the airway (shape of palate, length of upper teeth/inscisor gap) 2. surrounding tissues 3. pt physical characteristics (length and shape of neck receding mandible) 4. Mallampati and TMD.
Radiations/burns, C spine, limited ROM (can touch chin to chest or extend the neck, atlanto-occipital extension to align oral/pharyngeal axis), TMJ, RA, ankylosing spondylitis, abscess or tumor, prior intubation or trach, obesity, thyromegaly, scleroderma, snoring, sleep apnea? also congenital syndromes

Question 15

Describe airway classification based on Mallampati’s Hypothesis?

Answer 15

Mallampati classification system correlates the oropharngeal space with the ability to visualize the vocal cords correlating with the ease of laryngoscopy. “When the base of the tongue is disproportionately large, the tongue covers the larynx resulting in difficult view of the cords”
Observer should be at eye level, patient holds head in neutral position, opens mouth maximally, protrudes tongue without phonation.

Question 16

What are the classifications of the mallampati?

Answer 16

I. Soft palate, faucil pilars, uvula (correlates with a full view)

2. Tip of uvula is masked by the tongue, but soft palate and faucil pillars still in view. (chords still visible but not as much as class I)
3. Only soft palate and base of uvula are visible (no chords)
4. hard palate only (just epiglottis) consider a fiberoptic or awake intubation

Question 17

TMD?

Answer 17

Distance from lower mandible to thyroid notch with the neck fully extended.
Normal is 6-6.5 cm or 4 finger breaths, greater than 3 fingers indicates difficult intubation, receding mandible, anterior airway

Question 18

Describe the innervation of the larynx

Answer 18

The superior and recurrent laryngeal nerves, both branches of the vagus, innervate the larynx. The superior laryngeal nerve decussates into the internal and external branches. The internal branch provides sensory innervation above the VC, external branch provides motor innervation to the cricothyroid muscle ( only VC ABD). The RLN provides sensory innervation below the vocal cords, and motor to the other intrinsic muscles of the larynx besides the cricothyroid.

Question 19

Discuss anesthesia face mask use

Answer 19

Facemaks are important for patient ventilation and help ensure ability to ventilate before intubation or a administration of longer acting drugs.
Available in a variety of sizes, should fit over the bridge of nose to between lip and chin. Good seal vital.
Technique: hold mask in left hand and reservoir bag in right, put thumb on upper aspect of mask, index and middle finger on lower part of mask, 4th and 5th fingers lifting the mandible. May need to use two hands with an assistant bagging. head strap can cause nerve injuries, though.

Question 20

What are predictors of difficult mask ventilation?

Answer 20

Beard, increased BMI, lack of teeth, male gender, retarding mandible, history of snoring, advanced age, mallampati score of 3 or 4

Question 21

Describe the optimal intubation position

Answer 21

Patient positioning is vital to ensure success with laryngoscopy, esp for beginners. Patient should be supine, with neck extended using a pillow, in the “sniffing position”, this aligns the oral, pharyngeal, and laryngeal axis which provides a clear visualization of the vocal cords. This also allows for effective mask ventilation.

Question 22

What is the goal of pre-oxgenation?

Answer 22

Preoxygenating with 100% allows for patients to tolerate longer periods of time without desaturation. The goal is to denitrogenate the patient, or increase the O2 concentration in the FRC.
3-5 mins of tight seal, normal TV breathing, 100% O2 >5L= 10 minutes of apnea
4 vital capacity breaths in 30 seconds= 5 minutes of apnea. RSI, emergencies.

Question 23

What is needed for a proper airway setup?

Answer 23

Laryngoscope with 2 blade types
Several sizes of oral and nasal airways
Tongue depressor for insertion of OA
ETT 2 sizes with stylets
Suction
Ambu-bag
LMA, #4, through which you can place a 6.0 ETT (intubating LMA's can have a 8.0 ETT), lube; ASA guidelines for management of a difficult airway include use of an LMA. 
soft bite block and hard bite block

Question 24

What is the cause of an obstructed airway?

Answer 24

the tongue and epiglottis fall back to the posterior pharyngeal wall, occluding the airway

Question 25

Describe oral airways

Answer 25

``` Made of hard plastics, numerous sizes and shaped to curve behind the tongue, lifting it off the posterior pharynx. tongue is the most common cause of airway obstruction Two types: Berman and Guedal (can suction through) Small Berman (80mm)= Guedal #3 Medium Berman (90mm)= Guedal #4 Large Berman (100mm)= Guedal #5 ```

Question 26

What are the complications of an oral airway?

Answer 26

includes bleeding, soft tissue damage. Irritation to the supraglottic region could cause laryngospasm, life threatening. (nasal airways are less irritating, but epitaxial is a risk)

Question 27

What are nasal airways and their complications

Answer 27

Used to provide passageway from the nose to pharynx beneath the tongue. Size based on diameter, many sizes from 24,26,-36 French. Estimate length from nares to meatus of ear. Must lubricate. Better than oral airways. Complications: epistaxis, nasal or basal skull fx, adenoid hypertrophy, anticoagulant (coumadin)

Question 28

Describe the different laryngoscopes.

Answer 28

Macintosh: sizes 1-4 (usually a 3) Miller: 0-4 (usually a 2)

Question 29

Describe important numbers regarding ETT sizes and positioning.

Answer 29

ETT sizes (have 2 available) Females: 6.5 or 7 (21 cm) Males: 7.5 or 8 (23 cm) * position 4 cm above the carina and 2 cm below the vocal cords.

Question 30

What do the Trigeminal, glossopharyngeal, vagus nerve innervate?

Answer 30

1. Trigeminal: nasal mucosa 2. Glossopharyngeal: posterior 1/3 of the tongue and oropharynx to the vallecula Vagus's superior laryngeal nerver internal branch supplies sensory to the vocal cords and above the glottis (epiglottis, base of tongue, thyroepiglottic join, cricothyroid joint) 3. RLN supplies the mucosa below the cords (and motor to all intrinsic except cricothyroid) 4. SLN external division motor to cricothyroid

Question 31

What is the separation between the pharynx?

Answer 31

The nasopharynx is separated from the oropharynx by the soft palate. The oropharynx and the larygopharynx is separated by the epiglottis.

Question 32

What negative responses can tracheal intubation cause?

Answer 32

Cardiac: hypertension, tachycardia, MI Respiratory system: laryngospasm, bronchospasm * must have patient in a deep plane of anesthesia prior to manipulation of their airway with inhalation agents, narcotics, prophylactic bronchodilators, topical anesthesia or airway blocks.

Question 33

What are complications to tracheal intubation

Answer 33

``` Trauma to airway structures Esophageal intubation Endotracheal tube ignition Sore throat Laryngospasm Croup ```

Question 34

Why would you need an airway block

Answer 34

When examining the patient if the provider feels they cannot adequately ventilate or intubate the patient once they are anesthetized and paralyzed, awake intubation should be considered and an airway block is required. Also, patients with a history of difficult airways, morbid obesity, any issues that compromise the larynx or airway such as cancer or deformities). Important to consider sedation before the blocks, but we don't want them to lose spontaneous respirations because we wanted an awake intubation so they can breath spontaneously. Purpose is to abolish or blunt their reflexes, and for comfort. *risks include systemic toxicity and hematoma formation.

Question 35

What are the indications for a transtracheal block

Answer 35

To block the RLN for awake laryngoscopy, fiberoptic or retrograde intubation. Abolishes the gag reflex, hemodynamic response to the stress of larygoscopy. Helps avoid valsalva-like straining. Cough spreads the lidocaine transtracheally. * Results in anesthesia of the trachea below the vocal cords

Question 36

What are the landmarks and side effects of transtracheal blocks?

Answer 36

Cricothyroid membrane is palpated and air is aspirated to ensure proper placement. Side effect is a cough, this block should be avoided in patients where cough is undesirable.

Question 37

What are the indications of the SLN block?

Answer 37

To block the internal branch of the SLN (sensory). Blocks the mucosa above the supraglottic region, from inferior epiglottis to vocal cords. Abolishes the gag reflex to laryngoscopy or bronchoscopy for awake intubation.

Question 38

What are the indications for a glossopharyngeal block?

Answer 38

To block the lingual branch of the glossopharyngeal nerve, this supplies sensory to the back of the tongue. Abolishes the gag reflexes when topical is not effective.