Pulmonary Issues and PH Flashcards
What happens with inspiration in negative pressure ventilation
Inspiration leads to decreased pleural pressure which decreases RA pressure and increases the filling pressure gradient leading to increased RA filling (increased preload) and increased CO
What happens with inspiration in positive pressure ventilation
Inspiration leads to increased pleural pressure which increases RA pressure and decreases filling gradient leading to decreased preload and decreased CO
What causes increased V/Q
Mucus plugging, pulmonary edema
What causes decreased V/Q
Pulmonary emboli, emphysema
What causes of hypoxia lead to increased A-a gradient
Diffusion disorders
V/Q mismatch
Shunting
LPA sling
LPA comes off the RPA and courses between trachea and esophagus –> can lead to R bronchus and tracheal compression
What lung volume is PVR lowest
FRC
Definition of PH and PAH
- PH is mean PA pressure > 25
- PAH is mean PA pressure > 25, PVR > 3 and wedge < 15
WHO classifications of PH
- Pulmonary arterial
- Left heart disease
- Lung disease
- CTEPH
- Other (CHD)
Which genetic mutation is most common in PAH
BMPR2
What other genes are involved in PH
SMAD genes, ACVRL1 (HHT), CAV1, KCNK3, EIF2AK4 (PVOD)
What pathophysiology changes happen early in PH
- Abnormal muscularization of the distal pre-capillary arteries
- Endothelial dysfunction
- Fibroblast proliferation
- Thickening of muscular arteries
What pathophysiology changes happen late in PH
- Smooth muscle cells proliferate
- Neointima formation –> vessel occlusion
What heart sounds do you hear with PH
- Loud P2
- Right sided S3
- Holosystolic murmur (TR)
- Diastolic murmur (PI)
What pre-op PVR is high risk
> 6
What symptoms of PH put people in a higher risk category
- WHO classes 3 and 4
- Syncope
- RV dilation/dysfunction
- PVRi > 20
- CI < 2
- Significantly elevated BNP
- VO2 < 15
What class of med should be started with high risk PH patients with RV failure
Prostacyclins
Mechanism of action of PDE5 inhibitors
- Vasodilates by inhibiting degradation of cGMP by PDE5
Side effects of sildenafil/tadalafil
- Hypotension
- Flushing
- GI upset
- Blurred vision
- Epistaxis
- Priapism
Mechanism of action of ERAs
Block endothelin-1 activity (which is normally a pulmonary vasoconstritor)
Side effects of ERAs
Sinusitis, fluid retention, flushing, abdominal pain, anemia, LFTs (bosentan), teratogenic
3 ERA meds and their selectivity
- Bosentan –> blocks both ET-A and ET-B
- Ambrisentan –> selective for ET-A
- Macintenan –> non selective
How do prostacyclins work
Mimic endogenous prostaglandin I2 –> cAMP mediated vasodilation
Difference between two main prostacyclins
- Epoprostenol has 6 minute half life
- Treprostinil (remodulin) has 4.5 hour half life
Side effects with prostacyclins
Flushing, bone/jaw pain, abdominal pain, thrombocytopenia
