Airway

Question 1

At what level is the larynx in an adult?

Answer 1

C3-C6

Question 2

What are the functions of the larynx?

Answer 2

Airway protection, respiration, phonation

Question 3

What is the narrowest portion of the adult airway?

Answer 3

Glottic opening (triangular fissure between vocal cords)

Question 4

Name the paired cartilages of the larynx.

Answer 4

Arytenoid - posterior attachment to VCs (with ant. a/w may be only thing visible)
Corniculate - do not play prominent role in laryngoscopic appearance or function
Cuneiform - do not play prominent role in laryngoscopic appearance or function

Question 5

Name the unpaired cartilages of the larynx.

Answer 5

Thyroid - large and most prominent. Vocal cords anterior attachment
Cricoid
Epiglottis - covers opening to larynx during swallowing

Question 6

Describe the cricoid. Why is it unique?

Answer 6

Complete cartilaginous, signet-shaped ring

Narrowest point of the pediatric airway

Question 7

Describe the innervation of the intrinsic laryngeal muscles.

Answer 7

The intrinsic muscles are concerned with the movements of the laryngeal parts, making alterations in the length and tension of the vocal cords and in the size and shape.
All intrinsic muscles of the larynx are supplied by the recurrent laryngeal nerve (RLN), a branch of the VAGUS NERVE (CN-X).
**Except the cricothyroid muscle, which is supplied by the external branch of the superior laryngeal nerve.

Question 8

Name the intrinsic laryngeal muscles that open and close the glottis.

Answer 8

Lateral Cricoarytenoid (adducts)
Arytenoids (adduct)
Posterior Cricoarytenoid
-The ONLY VC ABductors

Question 9

Name the intrinsic laryngeal muscles that put tension on vocal ligaments.

Answer 9

Cricothyroid - also elongates vocal cords
Vocalis - Shortens the vocal cords
Thyroarytenoid - shortens and relaxes the vocal cords

Question 10

List the extrinsic laryngeal muscles (muscles that move larynx as a whole).

Answer 10

Sternohyoid, Thyrohyoid, Omohyoid
– moves hyoid bone caudad
Sternothyroid
– moves thyroid cartilage caudad

Question 11

Describe the trachea.

Answer 11

Fibromuscular tube
10-20 cm length & 22 mm diameter (Adult)
16-20 U shaped cartilages
Posterior side lacks cartilage
Bifurcates lower border T4 - carina
At carina:
Trachea divides into R & L mainstem bronchi
Angle of R bronchus = 2.5 cm long at 25*<
Angle of L bronchus = 5 cm long at 45*<

Question 12

Describe an airway evaluation/history.

Answer 12

Assessment includes:
Evaluation of the airway
Surrounding tissue
Pt physical characteristics
Goal is to identify potential airway problems and identify a difficult airway
Includes Mallampati and TMD
Note: It is not one factor but a combination of factors that create the difficult airway
What are questions to consider ?
Radiation or burn to head/neck?
C-spine pain of LROM?
TMJ pain?
Rheumatoid arthritis?
Ankylosing spondylitis?
Abscess or tumor?
Prior intubation or tracheotomy?
Snoring or sleep apnea?
Dysphagia or stridor?

Question 13

Describe the 4 classes of Mallampati.

Answer 13

Class I : faucil Pillars, Uvula, Soft palate, Hard palate
Class II: Uvula masked by tongue (Uvula, Soft palate, Hard palate)
Class III: Soft palate, uvula base (Soft palate, Hard palate)
Class IV: only Hard palate seen
Use PUSH mnemonic

Question 14

Define thyromental distance.

Answer 14

Distance from lower border of mandible to thyroid notch with neck fully extended
Normal 6-6.5 cm or 4 Fingerbreadths
Difficult intubation < 3 fingers, receding mandible

Question 15

What is the optimal intubating position and which three axis does it align?

Answer 15

“Sniffing” position- aligns the 3 axis:
oral
pharyngeal
laryngeal

Question 16

Describe the two methods of pre-oxygenation.

Answer 16

3-5 minutes “tight” mask fit normal tidal breathing of 100% O2 > 5L/min flow = healthy patient can tolerate up to 10 minutes of apnea

4 vital capacity breaths in 30 seconds = healthy patient can tolerate up to 5 minutes of apnea

Goal = Increased O2 concentration in FRC; decreased nitrogen in FRC (79% in RA)

Question 17

List items needed for an airway setup.

Answer 17

Laryngoscope /Blades 2 types
Oral/nasal airways several sizes
Tongue depressor
ETT Tubes 2 sizes
Suction
Ambu-bag
Stylet
LMA (difficult airway, usually #4)

Question 18

Describe the two types of oral airways, their common adult sizes, and complications/precautions.

Answer 18

Two types- Berman and Guedel
Adult sizes: small BOA (80 mm) = Guedel #3
medium BOA (90mm) = Guedel #4
large BOA (100mm) = Guedel #5
Complications/Precautions:
LARYNGOSPASM
Bleeding
Soft tissue damage

Question 19

Explain when a nasal airway might be used, tips, common sizes, and complications.

Answer 19

Used to provide passageway, nose –> pharynx beneath the relaxed and obstructing tongue
Diameter-French sizes 24, 26,…36 Length- estimated as distance from nares to meatus of ear
Lubricate!
Used in series (small to large) to dilate prior to elective nasal intubation
Usually tolerated better than oral airway during light anesthesia
Complications/Precautions: epistaxis, nasal or basal skull fractures, adenoid hypertrophy, anticoagulants

Question 20

List the adult male/female ETT sizes. How far down does the ETT go?

Answer 20

Adult ETT sizes:
Generally 2 sizes available
7.0 & 6.5 id for females
7.5 & 8.0 id for males

How far down does the ETT go?
Desirable position is 4 cm above the carina and 2 cm below the vocal cords
Males approximately 23 cm
Females approximately 21 cm

Question 21

Briefly review nerves that innervate the airway, differentiating between sensory and motor.

Answer 21

Sensory:
Glossopharyngeal
Internal Branch Superior Laryngeal
Recurrent Laryngeal

Motor:
External Branch Superior Laryngeal
Recurrent Laryngeal

Question 22

Explain the sensory innervation of the larynx.

Answer 22

Glossopharyngeal (9th CN)
Posterior 1/3 tongue and oropharnyx to vallecula

Internal Superior Laryngeal-
Branch of vagus - supplies sensory to vocal cords and above

Recurrent Laryngeal-
Branch of vagus - supplies mucosa below vocal cords

Question 23

Explain the motor innervation of the larynx.

Answer 23

External Branch Sup Laryngeal-
Supplies cricothyroid muscle- puts tension on vocal cords

Recurrent Laryngeal-
Supplies ALL intrinsic muscles of larynx EXCEPT cricothyroid muscle