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Posts Tagged ‘pa systolic pressure’

Pulmonary circulation  is a  low pressure  , low impedance  but  a high capacitance  system  . The job  of  pulmonary circulation  is  not only  to  ferry  the  blood from  right ventricle to  left atrium  ,   it should also ensure smooth gas exchange as it traverses the circuit . (How vital  it’s job is  . . . but we tend to be  obsessed with heart !)

The paradox is ,  for  the  flow of blood to occur you need a pressure head . (Note :  the pressure head is 120mmhg in systemic circulation.) The pulmonary  pressure head  is  only about 5-10mmhg it has to push the entire blood .(Pulmonary   pressure head  = Mean pulmonary artery pressure -mean LA pressure )

In  healthy persons

  • Pulmonary artery pressure (PAP)  is not supposed to increase beyond few mmhg.
  • The diastolic pulmonary artery pressure can not  afford to increase  even  those  few mm.

If it does , it  can cause serious hemodynamic and oxygenation issues. Both these statements are  based on  strong scientific  beliefs But now we realise the margin of these elevation has been revised a little higher  in normal persons .

  • In health ,  athletes can reach a systolic PAP  up to 40mmhg .
  • Diastolic PAP still largely remain a mystery . You can’t measure it when the patient is running you know !

Here is a recent article from chest  (2011) which documents pulmonary artery systolic pressure in trained athletes .

Relationship between exertional dyspnea and PA pressure.

The mechanism of  exertional dyspnea in any  individual is largely attributable  to  exercise induced pulmonary vascular  stretch .(J receptors etc ) . Many still believe  human functional  capacity is limited primarily by  the  lung function and the cross sectional areas of  pulmonary microvascular  bed .( Is this the  reason  two  patients with 25% EF  has vastly different functional capacity ?)

* Note : Exercise induced  pulmonary artery pressure  elevation are well-recognized in pathological states.

  • Mitral valve disease
  • In established COPD
  • In patients  with LV dysfunction

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