Pulmonary vasodilation will reduce the resistance of the pulmonary vascular bed.Inhaled pulmonary vasodilators yield three physiological advantages: #1) reduced pulmonary vascular resistance CO is diffusion limited because, CO is high in alveoli and diffuses easily but CO has a high affinity for Hb, so ul have very little CO that's free in the blood so it never equilibrates with CO from the alveoli, the only way to increase diffusion would be to increase the area of alveoli or to decrease thickness.Physiologic effects of inhaled pulmonary vasodilators.Perfusion limited, means that the only way to get more gas exchange Is to increase blood flow, O2 and CO2, at beginning of pulmonary capillaries low 02 high Co2 which is opposite of the alveoli so gasses equilibrate real quick even before they reach the end of capillary.So for example, in obstruction (Ards/Pulmonary Edema/ atelectasias/ foreign body obstruction) blood will shunt to left side of heart without hitting the lungs, and won't be alleviated by oxygen therapy contrasted to V/q mismatch due to a perfusion defect.Pathologic shunting is due to any condition where there the blood from the right side of heart bypasses the lungs and goes straight to left heart w/o oxygen, now that can be due to Right lo left shunts from a cardiac condition like tetralogy of fallot or Obstruction.Physiologic shunting u have some bronchial blood flow that doesn't go to alveoli to get oxygenated and joins the left side circulation of the heart, and also small coronary blood vessels that go from right side of the heart straight to the left ventricle and never get oxygenated, but its very small.So v/q mismatches can be due to A region that's ventilated but not perfused (dead space) like in PE like u said, or it can be due to Perfused areas and no ventilation (Shunt).
U have physiologic shunting and pathologic shunting.
0 kommentar(er)
