Missed apex flashcards
Define alveolar deadspace.
Ventilation without perfusion
List an example of anatomic dead space.
Nose/mouth–>terminal bronchioles
Ventilation is greatest at the _______ due to __________
base due to high alveolar compliance
Recite the alveolar gas equation.
Alveolar oxygen= FiO2 x (Pb-PH2O) - PaCO2/RQ
Rq = 0.8
PH2O= 47
The A-a gradient helps us diagnose the cause of
hypoxemia by quantifying the amount of venous admixture
A normal A-a gradient is
15 mmHg
The A-a gradient is increased by
high FiO2, aging, vasodilators, R to L shunt, and diffusion limitation
An awake intubation should be considered if an anticipated difficult airway is coupled with what 4 risks
suspected difficult mask ventilation
suspected difficult LMA placement
increased risk of aspiration
decreased apneic time
What is the maximum recommended peak inspiratory pressures for an LMA unique vs. LMA proseal vs. LMA supreme?
Unique: <20 cmH2O
Proseal & supreme: <30 cmH2O
What is the maximum ETT that will fit through a 2 & 2.5 LMA
LMA 2: 4.5
LMA 3: 5
When is a nasopharyngeal airway contraindicated?
Cribiform plate injury
coagulopathy
transphenoidal hypophysosectomy
nasal fracture
previous Caldwell-Luc procedure
Treatment for angioedema caused by ACE-I or C1 esterase deficiency?
FFP
icatibant
ecallintide
C1 esterase concentrate
5 risk factors for difficult invasive airway placement include
laryngeal trauma
altered neck anatomy (tumor, goiter)
obesity (can’t ID cricothyroid membrane)
Short, thick neck (can’t ID cricothyroid membrane)
Limited access to cricothyroid membrane (Halo, neck flexion deformity)
How many centimeters is a normal inter-incisor gap?
4 cm
(2-3 fingerbreaths)
What is the treatment for carbon monoxide poisoning?
100% FiO2 until CoHgb is <5% for 6 HOURS
hyperbaric O2 if CoHgb is >25% or pt. is symptomatic
What measures carbon monoxide and what is a s/sx?
Co-oximeter
cherry red appearance
If soda lime is desiccated, then volatile anesthetics can produce CO in the following order:
des>iso»» sevo
Pulmonary hypertension is defined as
a PAP >25 mmHg
What drugs increase pulmonary vascular resistance?
nitrous oxide
desflurane
ketamine
List the 5 drug classes that can be used for prevention of aspiration pneumonitis.
H2 blockers: famotidine, cimetidine
antiemetics: ondansetron
antacid: sodium bicitrate
GI stimulants: metoclopramide
PPI: protonix, omeprazole
What are four examples of extrinsic lung disease that affect the chest wall/mediastinum?
kyphoscoliosis
flail chest
mediastinal tumor
neuromuscular disorders
What is alpha 1 antitrypsin deficiency?
alveolar elastase is a natural enzyme that breaks down pulmonary connective tissue
this enzyme is kept in check by alpha 1 antitrypsin
will see pan lobar emphysema
What is the definitive treatment for alpha 1 antitrypsin deficiency?
liver transplant
An extrathoracic tumor is abnormal during
inspiration and normal during expiration
An intrathoracic tumor is abnormal during
expiration and normal during inspiration
Why can’t spirometry measure FRC?
because it includes RV
What are the five causes of hypoxemia?
low FiO2
hypoventilation
diffusion limitation
shunt
V/Q mismatch
What causes of hypoxemia have a normal A-a gradient?
low FiO2
hypoventilation
What causes of hypoxemia can be fixed with supplemental O2?
low FiO2
hypoventilation
diffusion limitation
V/Q mismatch
What tests can measure FRC?
Nitrogen wash out
helium wash in
body plethysmyography
What is the normal value for oxygen carrying capacity?
20 mL O2/dL
What is the normal value for oxygen delivery
1,000 mL O2 /min.
What increases closing volume?
CLOSE-P
COPD, left ventricular failure, obesity, surgery, extreme age, pregnancy
3 causes of primary hypercapnia include:
hypoventilation (decreased elimination)
increased CO2 production
rebreathing
What are the four areas of the respiratory center?
dorsal respiratory group
ventral respiratory group
apneustic center
pneumotaxic center
What is the role of the pneumotaxic center?
inhibitory of the dorsal respiratory group
What is the role of the apneustic center?
stimulatory of the dorsal respiratory group
What do peripheral chemoreceptors respond to?
decreased O2, increased CO2, increased H+
Where are peripheral chemoreceptors located?
Carotid body–> glossopharyngeal nerve
aortic arch–> vagus nerve
What things impair HPV?
vasodilators
dobutamine
Halogenated agents >1-1.5 MAC
Phosphodiesterase inhibitors
IV anesthetics DO NOT inhibit HPV
What is normal DLCO?
17-25 mmHg
What factors decrease DLCO?
decreased surface area
increased alveolar thickness
How is smoking harmful?
increased SNS tone
increased risk of infection
Increased sputum production
increased carboxyhemoglobin concentration
Short term benefits of smoking cessation include
SNS stimulating effects return to normal
P50 returns to near normal
