UNIT 1 Respiratory Flashcards by Jesica Nguyen

Which muscles tense & relax the vocal cords? Which muscles abduct & adduct the vocal cords?

Tense & Relax:

cricothyroid “cords tense”
thyroarytenoid “they relax” & vocalis

Abduct & Adduct:

thyroarytenoid & lateral cricoarytenoid: adduct
posterior cricoarytenoid: abduct

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Which muscles abduct & adduct the vocal cords?

Abduct: posterior cricoarytenoid: “please come apart”

Adduct: lateral cricoarytenoid: “let’s close the airway”

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Name 4 nerves involved in sensory innervation of the upper airway:

1) Trigeminal (CN V)
V1 (opthalmic): nares & anterior 1/3 of septum
V2 (maxillary): turbinates & septum
V3 (mandibular): anterior 2/3 of tongue

2) Glossopharyngeal (CN IX)
posterior 1/3 of tongue, soft palate, oropharynx, vallecula, anterior of epiglottis

3) SLN
internal branch: posterior side of epiglottis –> level of vocal cords
external branch: no sensory

4) RLN
below vocal cords –> trachea

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How does RLN injury affect integrity of the airway?

Bilateral:
acute = respiratory distress
chronic = no respiratory distress

Unilateral:
no respiratory distress

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How does SLN injury affect the integrity of the airway?

Bilateral:
hoarseness but no respiratory distress

Unilateral:
no respiratory distress

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Name 3 airway blocks, and ID the key landmarks for each one.

glosspharyngeal block: palatoglossal arch @ the anterior tonsillar pillar.
SLN block: greater cornu of hyoid.
Transtracheal block: Cricothyroid membrane

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Where does the adult larynx extend from?

What are the 3 paired & 3 unpaired cartilages of the larynx?

Adult larynx extends from C3-C6
unpaired: epiglottis, thyroid, cricoid
paired: corniculate, cuniform, arytenoid

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What is the treatment for laryngospasm?

100% FiO2
remove noxious stimuluation
deepen anesthesia
CPAP 15-20cmH2O
open airway w/ head extension, chin lift
Larson's maneuver
succinylcholine

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Describe how the respiratory muscles function during the breathing cycle.

Inspiration:

diaphragm & external intercostals (tidal breathing)
accessory: sternocleidomastoid & scalene m.

Expiration:
usually passive, (TIRE!)
- transverse abdominis
- internal rectus abdominis
- external obliques, secondarily via internal intercostals

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What is the difference between minute ventilation & alveolar ventilation?

MV = Vt x RR

AV: only measures the fraction of Ve that is available for gas exchanges

AV = (Vt- dead space) x RR

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Define the 4 types of dead space.

Anatomic (air confined to the conducting airways)
Alveolar (alveoli that are ventilated but not perfused)
Physiologic (Anatomic + Alveolar Vd)
Apparatus (Vd added by airway equipment)

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Provide an example for each type of dead space.

Apparatus = face mask/HME
Anatomic = nose/mouth/ trachea/ terminal bronchioles
Alveolar = Zone 1 alveoli
Physiologic = anatomic and alveoli

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What does the alveolar compliance curve tell you?

alveolar ventilation is a function of alveolar size & it’s position on the alveolar compliance curve.

best ventilated alveolar are the most compliant (steep slope of curve)
worst ventilated alveoli are the least compliant (flat portion of the curve)

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What does the V/Q ratio represent?

V/Q is the ratio of ventilation to perfusion

normal MV = 4L/min
normal CO = 5L/min
-> normal V/Q = 0.8

dead space V/Q –> infinity
shunt V/Q –> 0

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Define the West zones of the lungs

Zone 1
PA>Pa>Pv
dead space (ventilation w/out perfusion)

Zone 2
Pa>PA>Pv
waterfall (normal physiology)

Zone 3
Pa>Pv>PA
shunt (perfusion w/out ventilation)

Zone 4
Pa>Pist>Pv>PA
pressure in the interstitial space (i.e. pulmonary edema) impairs ventilation & perfusion

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Alveolar gas equation?

PAO2 = FiO2(Pb-PH2O) - (PaCO2/RQ) NEED TO KNOW THIS

tells us that hypoventilation can cause hypercarbia & hypoxemia.
normal = approx 106mmHg

Pb = 760mmHg sea level
PH2O = 47mmHg
RQ = CO2 elimination/O2 consumption = 200/250 = 0.8 
- RQ = 1 --> over feeding
- RQ < 0.7 --> starvation

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What is the A-a gradient, what is the normal range, and what factors increase it?

helps diagnose cause of hypoxemia
it is normally 5-15mmHg

It is increased by: (VHARD)
- Vasodilators
- High FiO2
- Aging
- R–>L shunting
- Diffusion limitation

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List the 5 causes of hypoxemia. Which ones are reversed w/ supplemental oxygen?

Reduced FiO2
Hypoventilation
Diffusion Limitation
V/Q mismatch
Shunt

1-4 are reversed w/ supplemental oxygen.

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Define the 5 lung volumes & give reference values for each.

inspiratory reserve volume (3000mL)
tidal volume (500mL)
expiratory reserve volume (1100mL)
residual volume (1200mL)
closing volume (variable - approaches RV in healthy young patients)

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Define the lung capacities & give reference values for each.

total lung capacity (5800mL)
vital capacity (4500mL)
inspiratory capacity (3500mL)
functional residual capacity (2300mL)
closing capacity (variable)

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FRC consists of? What factors influence FRC? Name an example of increased FRC?

FRC = RV + ERV (35mL/kg)

conditions that reduce FRC tend to reduce outward lung expansion and/or reduce lung compliance –> zone III (shunt) increases. PEEP restores FRC by reducing zone III

position changes
increased intraabdominal pressure/contents
anesthesia/NMB
surgical displacement

COPD or any condition that causes air trapping increases FRC

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Why can’t spirometry measure FRC?

Residual volume cannot be measured by spirometry

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Which 3 tests can measure FRC?

1) nitrogen washout
2) helium wash in
3) body plethysmography

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What is closing volume & what increases it?

Volume above residual volume where the small airways begin to close during expiration.

CLOSEP:

COPD
LVF
Obesity
Supine position
Extreme age
Pregnancy

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State the equation and normal value for oxygen carrying capacity

CaO2 = SaO2Hgb1.34 + PaO2*0.003

normal = 20mL O2/dL

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State the equation and normal value for oxygen delivery

DO2 = CaO2 x CO x 10

normal = 1000mL O2/min

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Discuss the factors that alter oxyhemoglobin dissociation curve

Left shift (love, increased affinity, decreased offloading to the tissues)

Right shift (release, decreased affinity, increased offloading to the tissues)

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What 3 ways is CO2 transported in the blood? Which one is 70%?

1) bicarbonate 70%!!!!

2) bound to Hgb 23%

3) dissolved in plasma 7%

CO2–> HCO3- requires carbonic anhydrase & release of HCO3- from RBC to plasma causes Cl- shift (aka Hamburger shift)
–> RBC increases in size

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Describe the Bohr effect

Bohr effect describes: O2 carriage

increased CO2 & decreased pH = RBC releases O2

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Describe the Haldane effect

Haldane effect describes CO2 carriage

Increased O2 causes RBC to release CO2 (lungs)

(Where as Bohr effect describes O2 carriage and releases O2)

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List the 3 primary causes of hypercapnia and provide examples of each

increased CO2 production (sepsis, overfeeding, malignant hyperthermia, shivering, seizures, thyroid storm, burns)
decreased CO2 elimination (a/w obstruction, increased Vd, increased Vd/Vt, ARDS, COPD, respiratory depression, drug OD, inadequate NMB reversal)
rebreathing (incompetent one-way valve, exhausted soda lime)

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Describe the 4 areas in the respiratory center

Medullary Respiratory Centers:
- Dorsal respiratory center: active during inspiration (respiratory pacemaker)
- Ventral respiratory center: active during expiration

Pontine Respiratory Centers:
- Pneumotaxic center: inhibits the DRC
- Apneuristic center: stimulates DRC

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Contrast the location & function of the central & peripheral chemoreceptors.

Central:

located in the medulla
responds to the [H+] in the CSF

Peripheral:
- located in the carotid bodies, nerves of Hering: CN IX (9) glossopharyngeal
- located in the aortic arch CN X (10) vagus
- responds to decreased O2, increased CO2, and increased H+

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Which reflex prevents overinflation of the lungs?

Hering-Breuer inflation reflex

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What is hypoxic pulmonary vasoconstriction?

It minimizes shunt by reducing blood flow through poorly ventilated alveoli… seen in one lung ventilation
a low PAO2 (NOT arterial) is the trigger that activates HPV! LOW PAO2!!!
effect begins immediately & takes 15mins for full effect.

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What (4) things impair HPV?

Anything that inhibits HPV increases shunt (perfusion w/out ventilation)

1) halogenated anesthetics >1-1.5MAC
2) PDE inhibitors
3) dobutamine
4) vasodilators

IV anesthetics DO NOT inhibit HPV

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What does the diffusing capacity for CO (DLCO) tell us? Normal range?

Using Fick’s law of diffusion, the DLCO tells us:
- surface area (decreased w/ emphysema)
- thickness (increased by pulmonary fibrosis & edema)

It tells us how well the lung can exchange gas.
Normal = 17-25mL/CO/min/mmHg

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How is tobacco smoke harmful?

increases SNS tone
sputum production
carboxyhemoglobin concentration
risk of infection

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Describe the short & intermediate term benefits of smoking cessation.

Short term benefits (doesn’t reduce risk of postop pulmonary complications)
- SNS stimulation dissipates after 20-30mins
- P50 returns to near normal in 12hrs (CaO2 improves)

Intermediate term effects (return of normal pulmonary function requires at least 6 weeks
- improved airway function, mucociliary clearance, sputum production, & pulmonary immune function
- CYP450 induction subsides after 6 weeks.

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Compare & contrast PFTs in obstructive vs. restrictive lung disease. Name an example of each:

Restrictive:
- Decrease in all lung volumes: FRC, RV, TLC, FEV 1 and FVC & FEV1
- normal FEV1/FVC ratio
- normal FEF25-75
- example is obesity

Obstructive:
- decreased FEV1/FVC & FEF25-75
- may have normal other values
- example is COPD

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Discuss the following pulmonary flow-volume loops: normal, obstructive, restrictive, and fixed obstruction

normal = upside down ice cream cone

obstructive = normal inspiration w/ expiratory obstruction (negative exponential slope)

restrictive = shape similar to normal loop but smaller & shifted to the R

fixed obstructive = inspiration & expiration are affected.

Give an example of a disease the produces the following pulmonary flow-volume loops: obstructive, restrictive, and fixed obstruction

obstructive = COPD
restrictive = pulmonary fibrosis and obesity (reduced lung volumes, normal FEV1 ratio and FEF25-75)
fixed obstruction = tracheal stenosis

What is the treatment for acute bronchospasm?

- 100% FiO2
- deepen anesthetic (IA, propofol, lidocaine, ketamine)
- inhaled B2 agonist (albuterol)
- inhaled anticholinergic (ipratropium)
- epi 1mcg/kg IV
- hydrocortisone 2-4mg/kg (takes several hours)
- aminophylline
- heliox to reduce airway resistnace

What is alpha-1 antitrypsin deficiency? What is the definitive treatment?

alveolar elastase is a naturally occurring enzyme that breaks down pulmonary connective tissue (acts like Drano) ; it’s kept in check by alpha-1 antitrypsin (produced in the liver)

alpha-1 antitrypsin deficiency –> increased alveolar elastase actions –> panlobular emphysema.

Liver transplant is the definitive treatment

Describe the goals & strategies for mechanical ventilation in the patient w/ COPD.

prevent barotrauma & reduce air trapping:

low Tv 6-8mL/kg
increased expiratory time
slow inspiratory flow rate to optimize V/Q matching
low PEEP is ok as long as air trapping doesn’t occur

Define restrictive lung disease

characterized by:

impaired lung expansion
decreased lung volumes
normal pulmonary flow rates

Give examples of intrinsic lung diseases (acute & chronic)

Acute: aspiration, negative pressure pulmonary edema

Chronic: pulmonary fibrosis, sarcoidosis

Give examples of extrinsic lung diseases (acute & chronic)

Chest wall/mediastinum: kyphoscoliosis, flail chest, NM disorders, mediastinal mass

Increased intraabdominal pressure: pregnancy, obesity, ascites

List the risk factors for aspiration pneumonitis.

trauma
emergency surgery
pregnancy
GI obstruction
GERD
peptic ulcer disease
hiatal hernia
ascites
difficult airway management
cricoid pressure
impaired airway reflexes
head injury
seizures
residual NM blockade

Describe the pharmacologic prophylaxis of aspiration pneumonitis.

antacids: sodium citrate, sodium bicarbonate, magnesium trisilicate

H2 antagonists: ranitidine, cimetidine, famotidine

GI stimulants: metoclopramide

PPI: omeprazole, lansoprazole, pantoprazole

antiemetics: droperidol, ondansetron

routine use of these agents for prophylaxis isn’t recommended

What is Mendelson’s syndrome?

chemical aspiration pneumonitis

risk factors:
- gastric pH <2.5
- gastric volume >25mL (0.4mL/kg)

Describe the treatment of aspiration.

tilt head downward or to the side (first action)

upper airway suction
lower airway suction is only useful for removing particulate matter (not helpful for acidic burn)
secure airway
PEEP to reduce shunt
bronchodilators to reduce wheezing
lidocaine to reduce neutrophil response
steroids probably don’t help
Abx only if WBC or fever >48hrs

Discuss the pathophysiology and treatment of flail chest.

Consequence of blunt chest trauma w/ multiple rib fractures. The key characteristic is paradoxical movement of the chest wall at the site of the fractures

Inspiration: injured ribs move inward & collapse affected region
Expiration: injured ribs move outward & affected region doesn’t empty

TX: epidural catheter or intercostal nerve blocks

Discuss pulmonary HTN, and discuss goals of anesthetic management.

mean PAP>25mmHg
causes: COPD, L heart disease, connective tissue disorders

goals: optimize PVR
- increase PaO2
- hypocarbia
- alkalosis
- decreased intrathoracic pressure (prevent coughing, normal lung volumes, spontaneous ventilation)
- drugs: inhaled NO, NTG, phosphodiesterase inhibitors, PGs, CCB, ACEI

Discuss the pathophysiology of CO poisoning

reduces O2 carrying capacity of the blood (L shift)
CO binds O2 binding site of HgB w/ 200x affinity of O2
–> oxidative phosphorylation & metabolic acidosis
Co-oximeter NOT pulse ox measures CO
cherry red appearance
-if soda lime is desiccated then volatile anesthetics can produce CO (Des > Iso > Sevo) Des produces CO the most

Discuss the treatment of CO poisoning

100% FiO2 x6hrs

hyperbaric oxygen if COHgb >25% or if the patient is symptomatic

List the absolute & relative indications for OLV

Absolute indications:

Isolation of one lung to avoid contamination
Control of Distribution of ventilation
Unilateral bronchopulmonary lavage

Relative:

surgical exposure
pulmonary edema s/p CABG
severe hypoxemia r/t lung disease

Discuss how anesthesia in the LDP affects the VQ relationship.

So think of this like blood flow

Nondependent lung:
- moves from flatter region (less compliant) to an area of better compliance (slope)
- ventilation is optimal in this lung

Dependent lung:
- moves from the slope to the lower, flatter area of the curve (less compliant)
- perfusion is best in this lung (gravity)
- reduction of alveolar volume contributes to atelectasis

net effect: ventilation is better in nondependent lung & perfusion is better in dependent lung. This creates VQ mismatch & increases the risk of hypoxemia during OLV

Discuss the management of hypoxemia during OLV

100% FiO2
confirm DLT position w/ bronchoscope
CPAP 10cmH2O to nonventilated lung
PEEP 5-10 to ventilated lung
alveolar recruitment maneuver
clamp pulmonary artery to non-ventilated lung
resume two-lung ventilation

What is mediastinoscopy, and why is it performed

performed to obtain biopsy of the paratracheal lymph nodes at the level of the carina. Helps to stage the tumor prior to lung resection

What are the potential complications of mediastinoscopy. What is most common?

hemorrhage & pneumothorax are most common

others:
- impaired cerebral perfusion
- dysrhythmias
- air embolism
- chylothorax
- hoarseness and/or VC paralysis

describe the mallampati score

assesses teh oropharyngeal space, helps quantify the size of the tongue relative to the volume in the mouth

I: pillars, uvula, soft palate, hard palate
II: uvula, soft palate, hard palate
III: soft palate, hard palate
IV: hard palate

describe the interincisor gap. What is normal?

ability to open the mouth directly affects ability to align the oral, pharyngeal, and laryngeal axes. A small interincisor gap creates a more acute angle b/n the oral & glottic openings, increasing the difficulty of intubation

normal = 2-3FB or 4cm

what is the thyromental distance & what values suggest an increased risk of difficult intubation?

helps estimate the size of the submandibular space

w/ neck extended & mouth closed, you can measure the distance from the tip of the thyroid cartilage to the tip of the mentum. DL may be more difficult if the TMD is <6cm (3FB) or greater than 9cm

What is the mandibular protrusion test and what values suggest an increased risk of difficult intubation?

assesses the function of the TMJ. Pt is asked to sublux the jaw, and the position of the lower incisors is compared to the position of the upper incisors

Class I: LI past UI & bite the vermilion of the lip
Class II: LI in line w/ UI
Class III: LI cannot move past UI (increased risk of difficult intubation)

What conditions impair atlanto-occipital joint mobility?

DJD
RA
ankylosing spondylitis
trauma
surgical fixation
Klippel-Feil
Down syndrome

Describe the Cormack & Lehanne score

helps measure the view we obtain during DVL

Grade I: full view
Grade II: partial cords, arytenoids
Grade III: epiglottis
Grade IV: soft tissue

5 risk factors for difficult mask ventilation

BONES
beard
obese (usually BMI>26)
no teeth
elderly (age >55)
snoring

list 10 risk factors for difficult tracheal intubation

small mouth opening
narrow palate w/ high arch
long upper incisors
interincisor distance <3cm
MP class 3 or 4
mandibular protrusion class 3
poor compliance of submandibular spce
TM distance <6cm or >9cm
neck is thick &amp; short
poor AO joint mobility

list 6 risk factors for difficult supraglottic device placement

limited mouth opening
upper airway obstruction 
altered pharyngeal anatomy
poor airway compliance
increased airway resistance
lower airway obstruction

list 5 risk factors for difficult invasive airway placement

abnormal neck anatomy
obesity
short neck
limited access to CT membrane
laryngeal trauma

what is angioedema?

result of increased vascular permeability that can lead to swelling of the face, tongue and airway: airway obstruction is an extreme concern

what are two common causes of angioedema? what is the treatment for each?

ACEI; tx = epi, antihistamines, steroids (just like anaphylaxis)

hereditary angioedema (C1 esterase deficiency); tx = C1 esterase concentrate or FFP (i.e. not epi, antihistamines, or steroids)

What is Ludwig’s angina?

bacterial infection characterized by a rapidly progressing cellulitis in the floor of the mouth. Inflammation & edema compress the submandibular, submaxillary, and sublingual spaces.

the most significant concern is posterior displacement of the tongue resulting in complete, supraglottic airway obstruction

What is the best way to secure the airway in the patient w/ Ludwig’s angina?

awake nasal intubation or awake trach

Describe the practice guidelines for preoperative fasting & use of pharmacologic agents to reduce the risk of pulmonary aspiration.

2hrs = clear liquids
4hrs = breast milk
6hrs = nonhuman milk, formula, solid food
8hrs = fried or fatty foods

ingestion of clear liquids 2hrs before surgery reduces gastric volume & increases gastric pH

list the 4 types of oropharyngeal airways. which are best suited for fiberoptic intubation?

Williams & Ovassapian

best for fiberoptic intubation

What is the best time to use an ESchmann introducer?

best time to use is when grade 3 view is obtained during DL (grade 2 is the next best time).

Likelihood of successful intubation is unacceptably low when a grade 4 view is obtained.

When is a nasopharyngeal airway contraindicated?

cribiform plate injury (LeFort II or III, basilar skull fx, CSF rhinorrhea, raccoon eyes, periorbital edema)
coagulopathy
previous transsphenoidal hypophysectomy
previous Caldwell-Luc procedure
nasal fracture

contrast the maximum recommended cuff pressures for an ETT vs. LMA

ETT <25cmH2O

LMA <60cmH2O

contrast the maximum recommended PIP for an LMA-unique vs. LMA-proseal vs. LMA-supreme

LMA-unique <20cmH2O
LMA-proseal <30cmH2O
LMA-supreme <30cmH2O

what is the largest size ETT that can be passed through each LMA size?

1 = 3.5
1.5 = 4
2 = 4.5
2.5 = 5
3 = 6
4 = 6
5 = 7

list 6 indications for the Bullard laryngoscope

PITTS

Pierre Robins
Impaired C-spine mobility
Treacher Collins
Thick neck
Small mouth opening (minimum 7mm)

~~~

Describe the proper placement of the lighted stylet

when the patient is supine, the trachea is anterior to the esophagus. therefore we can look at the quality of the light shining through the neck to determine if the tip is in the trachea or the esophagus

looking for a well-defined circumscribed glow below the thyroid prominence
if it’s diffuse, then it’s in the esophagus

5 indications for the use of a bronchial blocker

indicated for lung separation in the following patients

age <8
requires nasotracheal intubation
have a trach
have a single lumen ETT in place
require intubation after surgery & you want to avoid changing the DLT out

How can the lumen of the bronchial blocker be used during OLV?

insufflate O2 into the nonventilated lung
&
suction air from the nonventilated lung to improve surgical exposure

cannot:
- ventilate
- suction blood, pus, or secretions

2 indications for retrograde intubation

Unstable C-spine

Upper airway bleeding (cannot visualize glottis)

Only use if ventilation is possible, it takes longer like 5-7 mins for experienced users

compare & contrast the benefits of awake vs. deep extubation

awake:
- airway reflexes intact
- ability to maintain a/w patency
- decreased risk of aspiration

deep

decreased CV & SNS stimulation
decreased coughing

when is the best time to use an airway exchange catheter, and what can you do with it?

maintains direct access to the airway following tracheal extubation, thus is helpful during extubation of the difficult airway

what else can you do with it?
EtCO2 measurement
Jet ventilation
O2 insufflation

Things that increase A-a gradient

high fio2
aging
vasodilators
R- L shunting
diffusion limitation

Small underdeveloped mandible

“Please Get That Chin”
-Pierre Robin
- Goldenhar
-Treacher Collin’s
- Cri du chat

Large tongue

“Big Tongue”
-Beckwith Syndrome
-Trisomy 21 (downsyndrome)

Cervical spine anomaly

“Kids Try Gold”

Klippel- Fleil
Trisomy 21
Goldenhar

Know where SLN and RLN are located

Where is the needle inserted for Glossopharyngeal nerve block?

Palatoglossal arch (anterior tonsillar pillar)
Inject 1-2ml of local on both sides
There’s a 5% incidence of intracarotide injection (risk of seizure)

Where is the needle injected at for SLN block?

Inferior border of the greater Cornu of the hyoid bone
One ml injected outside thyrohyoid membrane, and 2ml injected deep to the thyrohyoid membrane
Repeat on both sides. Aspiration of air means needle is too deep