Pulmonary Circulation Flashcards Preview

CVPR: Pulmonary > Pulmonary Circulation > Flashcards

Flashcards in Pulmonary Circulation Deck (22)
Loading flashcards...

Function of broncial circulation

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


Consequences of bronchial circulation

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


General characteristics of blood flow/circulation as circuit

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


Calculating pulmonary vascular resistance

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


Steps in pulmonary circulation

-arteries -capillary network -veins


Systemic vs. Pulm

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


Pulmonary artery catheterization

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


Cardiopulmonary hemodynamics



Impact of gravity on pulmonary pressure

-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


Physiologic zones of pulmonary blood flow

  • Zone 1: PA > Pa > Pv
    • PA = alveolar pressure
    • Pa = arterial pressure 
    • Pv = venous pressure
  • Zone 2: Pa > PA > PV
    • Pa = Pv @ diastole
  • Zone 3: Pa > Pv > PA


PA > Pa (Zone 1) : no blood flows

-mechanical ventilation -Auto-PEEP (COPD)


Other regulatory mechanisms of pulmonary blood flow

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


Pulmonary edema

-originates in capillaries


Major function of pulmonary circulation

  • gas exchange
  • water and solute balance


major determinants of blood flow distribution in lung

  • gravity
  • hypoxic vasoconstriction


Major determinants of water and solute balance in lung

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


Major causes of pulmonary edema + general characteristics

  • 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


Characteristics of ARDS/Acute lung damage

  • "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


Hydrostatic vs. Non-hydrostatic pulmonary edema

  • 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


Pulmonary hypertension definition (+equation for Ppa)

  • 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
  • Ppa - PLA (drop in pressure across pulmonary capillary beds) = CO x PVR ==> 
    • Ppa = CO x PVR + PLA


Common mechanisms/causes of pulmonary hypertension

  1. increased PLA (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


WHO Classification of Pulmonary Hypertension

  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