GENERAL MEDICINE

GENERAL MEDICINE

Postby Dr_Sharada » Sat Jul 30, 2011 7:05 pm

general medicine....


PULSUS PARADOXUS- In a normal person the systolic blood pressure fall a little when the person inspires air..... this fall in the systolic BP is normal as long as it does not exceed 10mmHg...

The reason for this fall in the BP during inspiration is ... Every time a person inspires his INTRATHORACIC PRESSURE falls below the ATMOSPHERIC PRESSURE.. This is how the air rushes into the lungs.. THIS fall in INTRATHORACIC PRESSURE also affects the HEART.... inside
the HEART the RIGHT SIDE is affected differently than the LEFT SIDE
..

RIGHT SIDE OF THE HEART - This fall in pressure causes the blood from the systemic circulation to rush into the right side of the heart...Hence
INSPIRATION CAUSES INCREASE IN THE BLOOD SUPPLY TO THE RIGHT HEART..


LEFT SIDE OF THE HEART - The fall in the pressure has a different effect on the left heart.. the reason being the pressure in the lungs is much lower than the pressure in the left heart hence OVERALL effect will be -
LESS BLOOD SUPPLY TO THE LEFT HEART DURING INSPIRATION.
. To COMPENSATE for this fall in BLOOD SUPPLY the heart INCREASES ITS RATE OF CONTRACTION.. thus PULSE RATE IS INCREASED IN INSPIRATION..

Hence , normally the systolic BP falls a little and the pulse rate increases during INSPIRATION due to the effect on the LEFT HEART...


In PULSUS PARADOXUS , which is seen in cardiac tamponade,and lung disorders the PRESSURE in the LEFT VENTRICLE FALLS FURTHER either due to increased pressure in the pericardial region ( in cardiac tamponade) or due to extra increase in the INTRATHORACIC PRESSURE due to various lung disorders ( COPD, croup) .... Hence systolic BP falls below > 10mmHg during inspiration....
Dr_Sharada
 
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