Pulmonary Circulation

Question 1

How does compliance of pulmonary vasculature compare to systemic vasculature?

Answer 1

Pulmonary vascular is way more (7x) compliant.

Question 2

Normal mean arterial pressure (MAP) of the pulmonary circulation?

Answer 2

9-15 mmHg.
(vs. 85-100 mmHg in the systemic)
The resistance is also much lower

Question 3

How does blood flow vary in bases of lungs vs. apices?

Answer 3

More blood flow in bases, due to gravity.

Question 4

Cardio review: formula for pulmonary vascular resistance (PVR)?

Answer 4

(Mean PA pressure - Mean LA pressure) / Pulmonary Blood Flow

Question 5

What effects do increases pulmonary arterial and/or venous pressure have on PVR?

Answer 5

Increased pressures -> decreased resistance.

not sure how this fits in with the stated formula, though

Question 6

What effects do the extremes of changes in lung volume have on PVR?

Answer 6

Lungs to small or lungs too big both increase PVR.

Question 7

3 chemical stimuli that can increase PVR?

Answer 7

Acidemia.
Alveolar hypoxia. (hypoxic vasoconstriction to mitigate V/Q mismatch)
Hypercarbia.

Question 8

3 hormones that increase PVR?

Answer 8

Catecholamines, angiotensin, endothelins

Question 9

3 “hormones” that decrease PVR?

Answer 9

Acetylcholine, prostacyclin, NO.

Question 10

Defintion of pulmonary HTN?

Answer 10

Increased PA pressure, usually due to increased PVR.

Question 11

How can acute pulmonary embolism cause shunting?

Answer 11

Increased RA pressure can cause a patent foramen ovale (PFO) to open.
Additionally, shunt-like effects can be caused by blood flow being redirected to areas of low ventilation.

Question 12

What’s cor pulmonale?

Answer 12

Right heart failure..

Question 13

What was the point about sometimes the patient with the higher PA pressure is healthier?

Answer 13

The PA pressure can only be high if your heart is working. PA pressures will often decline with heart failure.

Question 14

Endothelial thickening, intimal proliferation, smooth muscle hypertrophy etc. etc. can contribute to pulmonary HTN.

Answer 14

Okay. We’re not really what the main driver of this process is.

Question 15

What’s a really good therapy for pulmonary arterial hypertension (PAH)… if you can be on a continuous drip?

Answer 15

Epoprostenol (Flolan) - a prostainoid.

There are other versions that can be given subcutaneously, or inhaled.

Question 16

Are endothelin antagonists helpful in PAH?

Answer 16

Yes.

Question 17

Why’s a bilateral lung transplant better than a single for PAH?

Answer 17

If a disease lung is left in, all the blood flow will be shunted to the healthy lung -> edema.