UNIT 1 Respiratory Flashcards
Which muscles tense & relax the vocal cords? Which muscles abduct & adduct the vocal cords?
STARE AT THIS PHOTO AND KNOW HOW TO LABEL EVERYTHING
Tense & Relax:
- cricothyroid “cords tense”
- thyroarytenoid “they relax” & vocalis
Abduct & Adduct:
- thyroarytenoid & lateral cricoarytenoid: adduct
- posterior cricoarytenoid: abduct
Which muscles abduct & adduct the vocal cords?
Abduct: posterior cricoarytenoid: “please come apart”
Adduct: lateral cricoarytenoid: “let’s close the airway”
Name 3 nerves involved in sensory innervation of the upper airway:
REVIEW THIS IN DEPTH! Write it out to make it stick!!!
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- review all of these
3) VAGUS innervates both of these:
- SLN
internal branch: posterior side of epiglottis –> level of vocal cords
external branch: no sensory
- RLN
below vocal cords –> trachea
How does RLN injury affect integrity of the airway?
Where does the right RLN and left RLN loop under?
Which side is more susceptible to injury?
Bilateral:
acute = respiratory distress
chronic = no respiratory distress
Unilateral:
no respiratory distress
-RLN innervated by Vagus nerves, the right RLN loops under subclavian artery, and the left RLN loops under the aortic arch. The left RLN is more susceptible to injury
Left side RLN injuries from: PDA ligation, left atrial enlargement (mitral stenosis), aortic arch aneurysm, thoracic tumor
Either side (right or left RLN) injury: pressure from ETT/LMA, thyroid surgery, neck stretching, neck tumor
Stare at this picture and be able to label everything
How does SLN injury affect the integrity of the airway?
Bilateral:
hoarseness but no respiratory distress
Unilateral:
no respiratory distress
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, ask pt to take a deep breath and inject 3-5ml of local into tracheal lumen
Where does the adult larynx extend from?
What are the 3 paired & 3 unpaired cartilages of the larynx?
Adult larynx extends from C3-C6 ( serves as airway protection, respiration, phonation)
unpaired: epiglottis, thyroid, cricoid
paired: corniculate, cuniform, arytenoid
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 I.M. Dose is 4mg/kg for child or adult. For neonates or infants it’s 5mg/kg Children < 5 years, give 0.02mg/kg of atropine to avoid bradycardia when giving Sux
how to reduce risk:
- CPAP 5-10 cm/H2O after extubation
- lidocaine
Describe how the respiratory muscles function during the breathing cycle.
KNOW THIS WELL!
Inspiration:
- diaphragm & external intercostals (tidal breathing)
- accessory: sternocleidomastoid & scalene muscles
Expiration:
usually passive, (TIREO!)
- transverse abdominis
- internal rectus abdominis
- external obliques, secondary role: internal intercostals
A vital capacity of at least 15mL/kg
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
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)
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
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)
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
Define the West zones of the lungs
Zone 1
PA>Pa>Pv
dead space (ventilation w/out perfusion)
Normal lung doesn’t have this. This increased by P.E and hypotension
Zone 2
Pa>PA>Pv
waterfall (normal physiology) more blood flow
Zone 3
Pa>Pv>PA
shunt (perfusion w/out ventilation)
Atelectasis
PA cath tip goes here
Zone 4
Pa>Pist>Pv>PA
pressure in the interstitial space pulmonary edema) impairs ventilation & perfusion
Alveolar gas equation?
PAO2 = FiO2(Pb-PH2O) - (PaCO2/RQ) NEED TO KNOW THIS
tells us that hypoventilation can cause hypercarbia & hypoxemia.
Pb = 760mmHg sea level PH2O = 47mmHg RQ = CO2 elimination/O2 consumption = 200/250 = 0.8 - RQ = 1 --> over feeding - RQ < 0.7 --> starvation
What is the A-a gradient, what is the normal range, and what factors increase it?
It compares partial pressure of O2 inside the alveolus and the partial pressure of O2 in the arterial circulation to diagnose the cause of hypoxemia. Get an ABG to get the PaO2 and use the Alveolar gas equation
- it is normally 5-15mmHg
It is increased by: (VHARD)
- Vasodilators: decreased hypoxic vasoconstriction
- High FiO2
- Aging
- R–>L shunt: Atelectasis, pneumonia, bronchial intubation, Intracardiac defect
- Diffusion limitation: pulmonary fibrosis, emphysema, interstitial lung disease
List the 5 causes of hypoxemia. Which ones are reversed w/ supplemental oxygen?
- Reduced FiO2- (A-a gradient is normal)
- Hypoventilation- (A-a gradient is normal)
- Diffusion Limitation- (A-a gradient is increased)
- V/Q mismatch- (A-a gradient is increased)
- Shunt- (A-a gradient is increased)
1-4: are reversed w/ supplemental oxygen
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)
Define the lung capacities & give reference values for each.
- total lung capacity (5800mL): IRV + TV + ERV + RV
- vital capacity (4500mL): IRV + TV + ERV
- inspiratory capacity (3500mL): ERV + TV
- functional residual capacity (2300mL): RV + ERV
- closing capacity (variable): RV + CC absolute volume of gas contained in the lungs when the small airways close
Vital capacity is 65-75ml/kg
FRC is 35ml/kg
Spirometry can’t measure RV, CC, and CV. It can’t measure TLC and CC FRC cus there’s RV in it. It CAN measure VC
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 elderly, any condition that causes air trapping increases FRC
Why can’t spirometry measure FRC?
Spirometry can’t measure residual volume so this includes (FRC and TLC). It also can’t measure closing capacity and closing volume
Which 3 tests can measure FRC?
1) nitrogen washout
2) helium wash in
3) body plethysmography
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
State the equation and normal value for oxygen carrying capacity
CaO2 = SaO2Hgb1.34 + PaO2*0.003
normal = 20mL O2/dL
State the equation and normal value for oxygen delivery
DO2 = CaO2 x CO x 10
normal = 1000mL O2/min
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)
What 3 ways is CO2 transported in the blood? Which one is 70%?
1) bicarbonate 70%!!!!
2) bound to Hgb by aminos 23%
3) dissolved in plasma 7%
CO2 to = HCO3- requires carbonic anhydrase & release of HCO3- from RBC to plasma, this causes Cl- shift out of the RBC (aka Hamburger shift)
Describe the Bohr effect
Bohr effect describes: O2 carriage
increased CO2 & decreased pH = RBC releases O2
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)
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
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
Contrast the location & function of the central & peripheral chemoreceptors.
Central:
- located in the medulla
- responds to the pH [H+] in the CSF
- CO2 diffuses freely in the BB and is hydrated with H2O (there’s no carbonic anhydrase involvement like in a RBC) = H+ and HCO3. The CSF responds to the H+. Increased H+ causes increase in Minute Ventilation and vice versa
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+
- Monitors PaO2 < 60mmhg. When it’s lower than this it closes the O2 sensitive K+ channels in the type 1 glomus cells
Which reflex prevents overinflation of the lungs?
Hering-Breuer inflation reflex
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!!! Pay attention to multiple choice questions
- effect begins immediately & takes 15mins for full effect
What (4) things impair HPV?
Anything that inhibits HPV, aka 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
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
How is tobacco smoke harmful?
- increases SNS tone
- sputum production
- carboxyhemoglobin concentration shifts curve to the left (hemoglobin binds to another atom prevent it from carrying oxygen)
- risk of infection
Describe the short & intermediate term benefits of smoking cessation.
Immediate 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
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
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, asthma
restrictive = pulmonary fibrosis and obesity
(reduced lung volumes, reduced FVC and FEV1, but with normal FEV1 ratio and normal 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), they’re bronchodilators!
- epi 1mcg/kg IV
- hydrocortisone 2-4mg/kg (takes several hours)
- aminophylline
- heliox to reduce airway resistnace
Pre-operative Albuterol does not help prevent respiratory risk
What is alpha-1 antitrypsin deficiency? What is the definitive treatment?
alpha-1 antitrypsin is produced in the liver. This deficiency is seen in COPD!!
alpha-1antitrypsin helps break down alveolar elastase enzyme. This alveolar elastase enzyme is like Drano in the lungs and destroys lung tissue.
With alpha-1antitrypsin deficiency, the alveolar elastase builds up and starts destroying more lung tissue = panlobular emphysema
It’s the MOST common metabolic disease affecting the liver
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, like 7bpm! SLOW THEIR RR!!!
- low PEEP is ok as long as air trapping doesn’t occur
- avoid regional blocks involving > T6
- if there’s hyperdynamic inflation (breath stacking): decrease RR, disconnect circuit, decrease inspiratory flow
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 with 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
Treatment: 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 Lateral Dependent position 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, any complications? Absolute contraindications?
performed to obtain biopsy of the paratracheal lymph nodes at the level of the carina. Helps to stage the tumor prior to lung resection
Complications #1 hemorrhage it’s near thoracic aorta, #2 pneumo
Absolute contraindications: previous mediastinoscopy due to scarring
know how to label the arteries on this!!!
Also the risk of a venous embolism is most likely to occur during spontaneous ventilation
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 & 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:
treat = epi, antihistamines, steroids (just like anaphylaxis)
Hereditary angioedema (C1 esterase deficiency):
treat = C1 esterase concentrate or FFP (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
- 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
- it’s a blind intubation technique
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 (DLT can do this too)
&
suction air only from the nonventilated lung to improve surgical exposure
cannot do any of this
- ventilate
- suction blood, pus, or secretions
- does not prevent contamination from contralateral lung infection because it can easily slip in trachea &, it’s super positional
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?
1) EtCO2 measurement
2) Jet ventilation
3) O2 insufflation
You can’t suction out of it
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 intracarotid 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
Transtracheal approach (RLN block) Where does the needle go?
Puncture the cricothyroid membrane
Advance needle in caudal direction to reduce risk of vocal cord injury.
3-5ml of local into tracheal lumen
What are all the letters blocking?
A is Glossopharyngeal nerve
B is SLN
C is RLN (transtracheal)
Kyphoscoliosis is expected to have a reduced:
FRC and FEV1
It’s restrictive disease
Is this example Extrathoracic obstruction or Intrathoracic obstruction?
The pt inhales and airway collapses and reduces flow. Pt exhales and pushes obstruction open, flow is normal, inspiratory limb is flat
Extrathoracic obstruction
Is this example Extrathoracic obstruction or Intrathoracic obstruction?
Pt inhales and pulls open the obstruction, flow is normal. Pt exhales and collapses airway, this reduces flow. Expiratory limb is flat
Intrathoracic obstruction
Extrinsic muscles that depress the larynx
O, Stern, Stern
Intrinsic laryngeal muscles:
Extrinsic laryngeal muscles:
Intrinsic laryngeal muscles: phonatation, and vocal cords (vocal cords are ligaments and are not innervated)
Extrinsic laryngeal muscles: support the larynx and swallowing
Discuss the 3 trigeminal nerves
There’s 3 CN that innervate the airway
1) Trigeminal CN5 (V1-V3, review the image below and know how to label it)
2) Glossopharyngeal CN 9
3) Vagus CN X (SLN & RLN)
Glossopharyngeal CN 9
Bilateral injury to the RLN
Topical anesthesia for upper airway
You need to anesthetize base of the tongue, oropharynx, hypopharynx, larynx. You don’t need to do the mouth
5 techniques:
1) Cotton soaked pledgets in the nares- Don’t use cocaine in PChE deficiency, increased SNS tone, or MAOI drugs
2) Instill topical local in each nare
3) Swish and swallow- but risk of N/V
4) Local anesthetic spray with 20% benzocaine- risk of methemoglobinemia tx with methylene blue
5) Nebulize
6) Atomization- works better than nebula
Glossopharyneal nerve block:
Where do you insert the needle?
What if you aspirate air or blood?
Insert needle at the base of the palatoglossal arch (anterior tonsillar pillar)
Aspiration of air = needle is too deep
Aspiration of blood = withdraw the needle and redirect medially. The carotid artery is very close. There is a 5% incidence of intracarotid injection, risk of seizure!
Superior laryngeal block:
Where is the anesthetic injected?
At the inferior border of the greater Cornu of the hyoid bone, then deep into thyrohyoid membrane. Repeat on the contralateral side
Aspiration of air = needle is too deep
Transtracheal block:
Where does the needle go?
Aka RLN block
Puncture the cricothyroid membrane in caudal direction to reduce vocal cord injury. After aspiration tell the patient to take a deep breath. During inspiration inject 3-5 mL in the tracheal lumen.
The patient will cough, spraying the local anesthetic upwards through the cords
How to insert nasal device?
Direct it between the inferior turbinate and the floor of the nasal cavity. Or orient the bevel (angled region) towards the turbinates
How does anesthesia affect airway patency?
- Obstruction at the level of the tongue
- Obstruction at the level of the soft palate
- Obstruction at the level of the tongue- genioglossus muscle relaxation
- Obstruction at the level of the soft palate- tensor palatine muscle relaxation
When compared to the trachea, which factor is GREATER in the terminal bronchioles?
A. Total cross-sectional area
B. Airflow velocity
C. Amount of cartilage
D. Quantity of goblet cells
A. Total cross-sectional area
The lower airway begins as a single tube (the trachea) and it bifurcates along 23 generations.
Things that increases as air bifurcates:
- number of airways
- total cross-sectional area
Things that are variable as airway bifurcates:
- muscular layer
What vertebral level corresponds with the adult trachea?
C6
Name 2 landmarks that correspond with the carina
T4-5
Angle of Louis
What structures permit air movement between alveoli?
Pores of Kohn
Type 1 and type 2 pneumocytes
Type 1= provides surface area for gas exchange
Type 2 = produces surfactant
What structures are anesthetized by injecting lidocaine at the base of the palatoglossal arch? (Select 2)
A. Oropharynx
B. Anterior 2/3 of tongue
C. Posterior side of the epiglottis
D. Vallecula
A. Oropharnx
D. Vallecula
Signs of laryngospam
- inspiratory strider
- suprasternal and Supraclavicular retraction during inspiration
- rocking horse chest, paradoxical movement
- increased diaphragmatic excursion
- lower rib flailing
- absent or altered EtCO2 wave form
Review the conducting, transitional, and respiratory zones
Know which one has Deadspace
Conducting zone- anatomic dead space Begins at the nares and ends with the Terminal bronchioles
Transitional zone- contains Respiratory bronchioles. Air conduit and gas exchange
Respiratory zone- where gas exchange takes place. Beings at alveolar ducts and extends to the alveolar sacs
What is the primary determinant of carbon dioxide elimination?
A. MV
B. TV
C. Alveolar ventilation
D. RR
C. Alveolar ventilation- determines removal of CO from the body
Alveolar ventilation = (tidal volume - dead space) x RR
An_______in PaCO2- EtCO2 gradient and causes CO2 retention
Increase
Increased PaCO2-EtCO2 gradient, think of = increased dead space
Examples of conditions that will most likely increase the PaCO2 to EtCO2 gradient:
- PPV- increases alveolar pressure which increases ventilation relative to perfusion, dead space increases
- Hypotension- reduces pulmonary blood flow which increases alveolar dead space
- Atropine- it is a bronchodilator, and increases anatomic dead space by increasing the volume of the conducting zone
- Hemorrhage
- Amniotic fluid embolism
What is the most common cause of increase Vd/Vt under GA?
Reduction in cardiac output. If the EtCO2 acutely decreases. You should rule out hypotension!
Vd/Vt ratio = the fraction of the tidal volume that contributes to dead space.
Vd= dead space = ventilation but no perfusion!
Things that increase Vd (dead space volume)
- face mask, HME
- PPV
- anticholinergics (bronchodilator increases the volume in the conducting airway)
- neck EXTENSION it opens the hypopharynx and increases it’s volume
- decreased cardiac output
- COPD
- P.E
- Sitting
3 ways to anesthetize the vocal cords
1) inject local through nasal airway or ETT positioned ABOVE the vocal cords
2) Spray as you go with FOB
3) Inject local anesthetic through multi-orifice epidural catheter that’s inserted into the suction port of a flexible Fiberoptic catheter
Nondependent lung V/Q ratio:
- V/Q ratio is higher, there’s more air here
- PAO2 is higher, there’s more air here but not perfusion so the alveoli just have a higher amount of O2 and lower PACO2
- More vascular resistance
- Perfusion and ventilation is LOWER, less compliance
Dependent lung
-V/Q ratio is lower here
- Better ventilation and perfusion
- Less vascular resistance
- PAO2 is lower and PACO2 is higher here= more blood flow so it’s diluted this is ALVEOLAR
V/Q mismatch
- Bronchioles constrict to minimize Zone 1
- Blood passing through underventilated alveoli tends to retain CO2
- A-a gradient is usually increased
- HPV minimizes shunt NOT dead space
What does the vocalis do?
Shorts and relaxes
Things that decrease FRC:
- GA
- Obesity
- Pregnancy
- Neonates
- Positioning: Supine, Lithotomy, T-burg
- Neomuscular blockade
- Light anesthesia
- Excessive IV fluids
- High Fio2 = absorption atelectasis
- Reduced pulmonary compliance
Things that increase FRC:
- Aging
- Prone
- Sitting
- Lateral
- Obstructive lung disease
- PEEP
- Sigh breaths
Closing capacity = sum of
Closing volume + residual volume
Which muscles participate in phonation and control the vocal cords (tension and position)?
Intrinsic muscles
Which muscles support the larynx inside the neck and assist with swallowing?
Extrinsic muscles
Are the true vocal cords innervated?
No, they are ligaments! They attach to the thyroid anteriorly and Arytenoids posterior
What does the thyroarytenoid do?
They relax and shorten and ADDucts vocal cords
What does the Aryepiglottic do?
Closes laryngeal vestibule
What does interarytenoid do?
Closes posterior commisure of glottis
Borders of laryngospasm notch (Larson’s maneuver)
Skull base, ramus of mandible, mastoid process
Pressure is applied towards the skull base. It displaces mandible anteriorly to open up the airway, and breaks the spasm so the pt will sigh.
Apply pressure for 3-5 seconds and released for 5-10 seconds. Repeat till spasm breaks
Distance from incisors to the larynx, what about to carina?
13cm to larynx
26 cm to carina
Deadspace = increased PaCO2 to EtCO2 gradient, list some examples
Think Deadspace = ventilation but no perfusion
-hemorrhage and hypotension- it reduces pulmonary blood flow and it increased alveolar dead space
- P.E.
- Atropine- bronchodilator, it increases the volume of the conducting zone (dead space area with nares and terminal bronchioles) so it reduces airway resistance
- PPV
Where are the peripheral chemoreceptors located and what does it respond to? What is its purpose?
Transverse aortic arch and carotid bodies.
They respond to PaO2 < 60mmhg, goal is to restore PaO2: Review how it does this
- When PaO2 < 60, it closes O2 sensitive K+ channels in type 1 glomus cells
- Raises RMP and opens Ca2+ channels to release = ATP and Ach!
- AP goes down hering nerve to glossopharyngeal nerve 9
- Afferent pathway terminates in inspiratory center in the MEDULLA
- Minute ventilation increases to restore PaO2!
We avoid bilateral CEAs because it severs the afferent limb
J-receptors in the lungs
Activated by things that JAM TRAFFIC like a P.E. Or CHF. Once stimulated it causes tachypnea
What medications increase intrapulmonary shunt?
A. Etomidate
B. Ketamine
C. Desflurane
D. Propofol
C. Desflurane > 1.5 MAC, CCB, vasodilators, Dobutamine = increase shunt by inhibiting HPV
HPV reduces shunt by diverting blood flow from under ventilated alveoli, occurs in seconds and lasts for 15 minutes. it’s a protective mechanism during atelectasis and OLV
Inhaled volatile agents increase shunt fraction and reduce PaO2
IV anesthetics do not affect shunt
Name some things that increase intrapulmonary shunt
Increase in shunt means = they impair hypoxic pulmonary vasoconstriction
- inhaled volatile anesthetics > 1.5 MAC
- CCB,Dobutamine, vasodilators
- Cardiac output elevation like hypervolemia LAP < 25 mmHg = distend constricted vessels and increase shunt flow
- PEEP and high tidal volumes = increase zone 1 Deadspace and cause V/Q mismatch
Anemia and CO poisoning = evening though CaO2 is reduced in both, PaO2 is usually normal. So this is why it doesn’t stimulate the hypoxic ventilatory drive.
Hypoxic ventilator drive is stimulated by low PaO2
because peripheral chemoreceptors only respond to low PaO2 < 60mmHg and NOT SaO2 and CaO2
PACO2
Des and sodium Nitroprusside
HPV during OLV reduces shunt do giving things that inhibit HPV will promote hypoxemia
Bronchoconstriction occurs by:
1) PNS supplied by vagus nerve: Phospholipase C activates ionositol triphosphate (IP3) = contraction
2) Mast cell release: leukotrines, complement, cytokines, IgE
3) Non cholinergic C fibers
Review what bronchoconstricts and bronchodilates
These are involved in bronchoconstriction:
Review this chart
What is the best indicator for small airway disease
Mid maximal expiratory flow rate MMEF, also known as FEF 25-75%
If it’s <70% = obstructive disease!!!!!
READ THIS AND KNOW HOW TO LABEL IT!!!!
Obstructive vs. Restrictive lung disease
REVIEW
Vagal stimulation
Airway smooth muscle is not innervated by SNS so a reduction in SNS can’t cause a bronchospasm.
Bronchospam is caused by a direct PNS stimulation, the intubation activated a vagal response leading to bronchospasm
Name things that can precipitate and things that can occur in Asthma:
- esosinophila
- vagal stimulation due to PNS stimulation
- cold air
- BB, sulfites, NSAIDS
Obstructive diseases: low FEV 1, FEV1/FVC ratio, FEF 25-75%, respiratory alkalosis
- right heart strain axis deviation
- PFTs not a predictor of post op complications
- TLC is NORMAL but FRC is increased
- CXR: hyperinflated with diaphragm flattening
Ventilator: you want to prolong expiratory time with permissive hypercapnia
Avoid: sux, atracurium, Mivacurium, meperidine, morphine = histamine release. Cisatracurium is fine!
Anticholinesterases can also cause bronchospasm
Bronchospasm
Dynamic hyperinflation seen in COPD/ aka breathing stacking or auto-peep
List 3 causes of auto-peep:
List 2 body systems affected by it:
Auto-peep:
1) high minute ventilation
2) reduced expiratory flow
3) increased airway resistance
2 systems affected by dynamic hyperinflation/autopeep:
Cardiac and pulmonary
Ventilator associated pneumonia
Caused by contamination, so you want to limit sedation, oropharyngeal contamination, want HOB > 30 degrees, want to do subglottic suctioning
Prophylaxis for GI bleed is not recommended bc it increases bacterial stomach growth. Routine prophylaxis is also not recommended for pts not a risk of aspiration
Know that magnesium trisilicate is a anatacid
Common culprits are pseudomonas aeruginosa and s. aureus
List things that can increase and decrease PVR
Iloprost can help decrease PVR
Carbon monoxide ABG and tx:
Metabolic acidosis (reduces ATP production)
Tx: 100% Fio2 for 90 minutes until COhgb is less than 5%, hyperbaric O2 if symptomatic if Cohgb exceeds 25% of hgb
Affinity of CO for O2 is 200x that of O2
When would you need to mechanically ventilate?
Absolute contraindications for OLV:
KNOW THIS IN DETAIL! Matching question
Double lumen tube
DLT sizing
8 year old - 26
10 year old- 28-32
DLT positioning
OLV hypoxia management
Know these exact steps
3 nerves that could be injured with an LMA
- Lingual
- hypoglossal
- RLN
LMA
Proseal and Supreme have gastric port and a bite block. Supreme is the single use disposable version in this photo
LMA
Combitube
Benefits of combitube
Contraindications of combitube
King laryngeal tube
FOB
- hold it in the non dominant hand and use thumb to control it. Pressing down moves it up
What are some contraindications?
Keys points about FOB
Requires minimum mouth opening of 7mm
Useful for Pierre Robin and Treacher Collin’s
This is a Bullard scope (rigid Fiberoptic device) you can use it on kids. There is a disposable tip extender for tall patients
Cricoid pressure helps with intubation, glottic exposure when the handle is pulled anteriorly
There are no contraindications for it
Eschman introducer
Advance into trachea at 23-25cm, hold up sign is resistance at carina, feeling clicks of trachea rings confirms proper placement
Microstomia- small mouth opening
Mandibular hypoplasia
It’s good for oral bleeding- cus it’s hard to visualize
Lighted stylet
Don’t use it in short thick fat necks, tumors, can’t’ ventilate scenarios
Unstable cervical spine
Upper airway bleeding
Retrograde intubation
Most important thing is to clamp with a hemostat at the skin of the neck so the wire doesn’t dislodge, before attempting to thread the ETT over the wire
Contraindications
Call for help
Airway fire steps:
1) remove airway
2) stop FGF
3) pour saline
4) re-establish ventilation
How much does the Ph decrease by each 10mmhg change?
0.08
Ex: Assuming ph 7.4 what is the expected ph if the paco2 increases from 40 to 60mmhg
It changed by 20mmg
So 7.4 subtract by 0.16 = 7.24
