Pulmonary Circulation

Question 1

What are the key features of pulmonary circulation?

Answer 1

Low pressure system
High compliance/distensability
Low resistance
High volume

Question 2

Describe Zone 1

Answer 2

PA>Pa>Pv

Large V/Q mismatch with almost no perfusion, collapse

Question 3

Describe Zone 2

Answer 3

Pa>PA>Pv

Driving force for perfusion

Question 4

Describe Zone 3

Answer 4

Pa>Pv>PA

Over-perfused, majority of exchange

Question 5

What is the function of hypoxic vasoconstriction?

Answer 5

Shutting off perfusion to under-ventilated areas for more efficient transport and V/Q match

Question 6

Under what condition does pulmonary edema develop?

Answer 6

Hydrastic pressure normally exceeds oncotic and fluids flow into the interstitium and is removed by lymphatics before alveolar flooding occurs. Edema is the result of flooding

Question 7

What are the two types of pulmonary edema?

Answer 7

Hydrostatic/Hemodynamic Edema

Permeability Edema

Question 8

What causes hemodynamic edema?

Answer 8

Fluid backup from left heart failure or volume overload from renal failure. Treat with diuretics.

Question 9

What causes permeability edema?

Answer 9

Alveolar epithelial injury (non-cardiogenic), slower onset than hemodynamic. Diuretics do not treat it.

Question 10

What causes pulmonary hypertension?

Answer 10

Increase in pulmonary vascular resistance or cardiac output

Question 11

What are the 5 classifications of pulmonary hypertension?

Answer 11

Class 1- Pulmonary artery hypertension
Class 2- PH from left heart disease
Class 3- PH from lung disease/hypoxia
Class 4- Chronic thromboembolic PH (CTEPH)
Class 5- Other

Question 12

What is the presentation of Idiopathic Pulmonary Arterial Hypertension (IPAH)?

Answer 12

PAH with no other cause, young women, cor pulmonale. Death from low CO or arrhythmia (~2 years)

Question 13

What are the risk factors for CTEPH?

Answer 13

Immobilization, hormonal manipulation, cancer, recent surgery