Pulmonary Circulation

Question 1

Function of broncial circulation

Answer 1

• protects lung from infarction
• can “grow into” areas of diseased lung (intercostal arteries

Question 2

Consequences of bronchial circulation

Answer 2

• usual source of hemopytosis
• much of arterial flow drains into left atrium = shunt

Question 3

General characteristics of blood flow/circulation as circuit

Answer 3

-R/L sides of heart pump to pulmonary and systemic -capillary beds = source of resistance -driving force ==> voltage = pressure -

Question 4

Calculating pulmonary vascular resistance

Answer 4

PAP (pulm. artery pressure) - LAP (left atrial pressure) = CO * PVR (pulmonary vascular resistance)

Question 5

Steps in pulmonary circulation

Answer 5

-arteries -capillary network -veins

Question 6

Systemic vs. Pulm

Answer 6

-systemic: high resistance vessels, high elastance/low compliance, high pressure system -pulmonary: low resistance, low eslastance/high complaice, low pressure system

Question 7

Pulmonary artery catheterization

Answer 7

-swan-ganz catheter -flow-directed pulmonary catheter -obstruct small pulmonary artery -make static water colum -measure distal pressures

Question 8

Cardiopulmonary hemodynamics

Answer 8

[picture/table]

Question 9

Impact of gravity on pulmonary pressure

Answer 9

-much higher pressure @ base vs. apex -gravity impacts blood pressure but not air pressure -blood flow is intermittent near apex b/c there are points @ which the arterial pressure is lower than alveolar

Question 10

Physiologic zones of pulmonary blood flow

Answer 10

• Zone 1: P_A > P_a > P_v
  
  • P_A = alveolar pressure
  • P_a = arterial pressure
  • P_v = venous pressure
• Zone 2: P_a > P_A > P_V
  
  • P_a = P_v @ diastole
• Zone 3: P_a > P_v > P_A

Question 11

PA > Pa (Zone 1) : no blood flows

Answer 11

-mechanical ventilation -Auto-PEEP (COPD)

Question 12

Other regulatory mechanisms of pulmonary blood flow

Answer 12

-hypoxic pulmonary vasoconstriction -vasoconstriction @ areas w/alveolar hypoxia -serves to preserve V/Q matching

Question 13

Pulmonary edema

Answer 13

-originates in capillaries

Question 14

Major function of pulmonary circulation

Answer 14

• gas exchange
• water and solute balance

Question 15

major determinants of blood flow distribution in lung

Answer 15

• gravity
• hypoxic vasoconstriction

Question 16

Major determinants of water and solute balance in lung

Answer 16

• Starling’s Law ==> fluid filtration is determined by difference in hyrostatic pressures inside and outside capillary in balance w/oncotic pressures

Question 17

Major causes of pulmonary edema + general characteristics

Answer 17

• increased hyrdostatic pressure (i.e. in LHF)
  
  • often occurs rapidly, can respond rapidly to tx
  • sign: Kerley B lines = enlarged lymphatic channels along interlobular septa engorged w/edematous fluid
• increased permeability of the capillary membrane (i.e. endothelial damage)
  
  • occurs slowly, slow or no response to tx
  • ARDS/acute lung injury = possible cause

Question 18

Characteristics of ARDS/Acute lung damage

Answer 18

• “Adult respiratory distress syndrome”
• alveolar/endothelial damage ==> fluid leak into aveoli
  
  • ==> shunt past fluid-filled alveoli or V/Q mismatch w/poorly ventilated alveoli
• occurs 6-24 hours after tissue injury
• possible causes: trauma, inhalation of toxic gas, aspiration, embolism

Question 19

Hydrostatic vs. Non-hydrostatic pulmonary edema

Answer 19

• Hydrostatic
  
  • Hx of recent/fast onset
  • Sx of HF
  • high LA pressure (pulm. cap wedge pressure)
  • responds to diuretic tx
• Nonhyrdostatic
  
  • Hx of slower onset + exposure to traumatic stimulus
  • No Sx of HF
  • normal LA pressure
  • does not respond to diuretics

Question 20

Pulmonary hypertension definition (+equation for P_pa)

Answer 20

• Pulmonary hypertension = pathologic state characterized by an increase in mean pulmonary arterial pressure
• Normal pulmonary pressure=25/10 with a mean of 15 mmHg
  
  • mean pressure > 25 mmHg = pulmonary hypertension
• P_pa- P_LA(drop in pressure across pulmonary capillary beds) = CO x PVR ==>
  
  • P_pa = CO x PVR + P_LA

Question 21

Common mechanisms/causes of pulmonary hypertension

Answer 21

1. increased P_LA (such as in heart failure or mitral stenosis
2. increased PVR​​
3. increased cardiac output
   
   • ​​not normally a major cause of pulmonary HTN due to increased vessel recruitment and dilation

Question 22

WHO Classification of Pulmonary Hypertension

Answer 22

1. Pulmonary Arterial Hypertension
2. PH due to Left Heart Disease
3. PH due to Lung diseases
4. Chronic thromboembolic pulmonary hypertension
5. PH w/unclear/multifactorial mechanism