Things to Work On... Flashcards
Discuss the pathophysiology of chronic bronchitis vs emphysema:
Bronchitis: caused by inflammation and mucous production that reduce airway diameter
Emphysema: caused by a reduction in the surface area of the alveolocapillary interface and loss of elastic recoil
Discuss the blood gas differences between chronic bronchitis and emphysema:
Bronchitis: polycythemic due to increased RBC that compensates for a chronically low PaO2. CO2 is retained. “Blue Bloater”
Emphysema: normal (or slightly reduced) PaO2. PaCO2 normal or decreased (due to hyperventilation). “Pink Puffer”
Discuss cor pulmonale in chronic bronchitis vs emphysema:
Usually occurs in bronchitis due to pulmonary hypertension.
Chronic alveolar hypoxia -> pulmonary vasoconstriction -> increased pulmonary vascular resistance -> workload RV increases -> RV hypertrophy (right axis deviation) -> RV failure
Discuss high altitude and resultant A-a gradient:
A-a gradient = normal
O2 helpful = yes
Example = low barometric pressure
Discuss hypoventilation and resultant A-a gradient:
A-a gradient = normal
O2 helpful = yes
Example = low PAO2, opioid overdose
Discuss diffusion defect and resultant A-a gradient:
A-a gradient = increased
O2 helpful = yes
Example = pulmonary fibrosis
Discuss V/Q mismatch and resultant A-a gradient:
A-a gradient = increased
O2 helpful = yes
Example = dead space, shunt
Discuss Right to Left Shunt and resultant A-a gradient:
A-a gradient = increased
O2 helpful = no (if shunt > ~ 30%)
Example = Tetralogy of Fallot, Eisenmenger Syndrome, VSD??
Discuss respiratory reserve using respiratory mechanic function tests:
Tests the ability to move gas in and out of the lungs
FEV1 < 40% is the best measurement
Discuss respiratory reserve using case exchange function tests:
Tests the ability to transfer O2 and CO2 across the alveolocapillary interface
DLCO <40% is the best measurement
PaO2 < 60 mmHg
PaCO2 >45 mmHg
Discuss respiratory reserve using cardiorespiratory interaction function tests:
Tests the ability of the lungs and heart to work together to maintain PaO2 and PaCO2
VO2 max < 15 mL O2/kg/min is best measurement
Unable to climb 1 flight of stairs
SpO2 decreases >4% during exercise
Easy ways to identify A-a gradients:
Normal: A-a gradient < FiO2
Abnormal: A-a gradient > FiO2
Estimated PAO2: FiO2 x 6
PaO2: read on ABG
What is the trigger that activates hypoxic ventilatory vasoconstriction?
low alveolar PO2 aka PAO2
What is the maximum cuff pressure for an ETT? LMA?
25 cm H2O
60 cm H2O (target pressure 40-60 cm H2O)
NCE order for airway fire steps:
Fire is present:
1. Remove ETT
2. Stop flow of airway gases
3. Remove other flammable materials from the airway
4. Pour saline into the airway
5. If fire not extinguished on first attempt, use a CO2 fire extinguisher
Once fire is controlled:
1. Re-establish ventilation by mask; avoid supplemental O2 or N2O
2. Check ETT for damage - fragments may remain in the airway
3. Bronchoscopy to assess the injury and retained ETT fragments
Discuss NMBs and myasthenia gravis:
sensitive to nondepolarizers
resistant to succinylcholine
Discuss NMBs and Eaton-Lambert syndrome:
sensitive to both nondepolarizers and depolarizers
Discuss NMBs and Guillain Barre:
sensitive to nondepolarizers
avoid depolarizers (hyperkalemia due to extra-junctional Ach receptors)
Discuss NMBs and hypo/hyperkalemic periodic paralysis:
nondepolarizers are safe - may be sensitive so use short acting
avoid succinylcholine
Can succinylcholine be used in multiple sclerosis?
No, life threatening hyperkalemia
Discuss NMBs and myotonic dystrophy:
Sux - increase risk of contractures
Use nondepolarizers
reverse with sugammadex
Which volatile anesthetic impairs the hypoxic ventilatory response the LEAST?
Desflurane
(corresponds with hepatic metabolism)
Which volatile anesthetic is most likely to cause bronchospasm?
Desflurane
What are carotid bodies more sensitive to?
changes in PaO2, PaCO2, and H+ ions
(glossopharyngeal innervation)
