Ryan explains it in his video is that pure dead space doesn't cause hypoxemia because the desaturated Hb thats going to the dead space alveoli never reaches the arterial side of the circulation, since there's a block in the vessel. Yeah, but why does dead space only affect CO2? Since Q goes up, V/Q goes down - that's V/Q mistmach which causes hypoxemia. Areas of lung that are perfused in PE have very high blood flow (Q) since blood cannot go through all normal channels due to clot. Hypoxemia occurs in PE due to V/Q mismatch.
Also there is hypoxemia in PE, but not because of the dead space (because dead space doesn't case low O2). This is because patients hyperventilate to keep Co2 normal despite dead space. There is dead space, but usually not hypercapnia. Leaves more CO2 behind in the blood so CO2 rises. Air goes in and out without picking up CO2. Dead space is ventilated but not perfused. Net result: oxygen fails to improve O2.ĭead space: Has nothing to do with O2, only CO2. So oxygen does not help because it can't get to shunt areas (no ventilation) and it can get to non-shunt areas which are already fully oxygenated. Non-shunted areas are fully oxygenated (100%). Henceforth, physiologic dead space is more clinically helpful than anatomic dead space.In a shunt, blood good from right heart to left heart without passing ventilated areas (i.e., does not pick up oxygen). But people with bad health conditions of the lung are inadequately perfused, the physiologic dead space might be extensively bigger than the anatomic dead space. Note:According to observation, the anatomic and physiologic dead spaces are generally proportional to healthy people as all parts of the lung are very much perfused. So the correct answer will be option A, i.e., Upper respiratory tract. Less effective at exchanging gas with the blood. Yet in addition factors in alveoli which are very much ventilated but ineffectively perfused.
It incorporates all the non-respiratory functional parts of the bronchial tree remembered for anatomic dead space. The volume of anatomic dead space is around 150 ml in people.Īll the air that gets gathered in dead space never takes any part in the gaseous exchange it means oxygen which goes to that bit is not useful for the human body.Īll these functions carry on the Upper respiratory tract of the human body.Īdditional information:The other type of dead space is a physiologic dead space. Majorly there are two types of dead space namely physiologic dead space and anatomical dead space.Īnatomic dead space is the complete volume of the moving airways from the nose or mouth down to the degree of the terminal bronchioles. Hint: It shows the volume of ventilated air (air enters the lungs) that does not take part in gas exchange.
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