They also show that the increase in pCO 2 can be avoided by even modest increases in total alveolar ventilation (although the calculated dead space will remain elevated). This will increase the calculated physiological dead space accordingly (above that normally present due to the volume of air in the conducting airways). Ventilation may exceed perfusion in parts of the lung resulting in increased physiological dead air space.In the previous issue of Critical Care, Niklason and colleagues use computer modeling to point out that blood flowing through unventilated regions of the lung (a shunt) will increase arterial partial pressure of carbon dioxide (pCO 2) if ventilation remains constant. Air may reach the periphery of the lungs but fail to make contact with the capillary blood. The alveoli become permanently damaged (see video above).This is why breathlessness and fatigue are common symptoms of COPD. This extra effort can make the patient feel very tired. However, this does not mean that your oxygen levels are low because the breathing muscles around the chest are working harder to compensate. The respiratory muscles then have to work harder to get air in and out of your lungs.As the lungs become hyper-inflated they elongate and flatten, which means the diaphragm does not work as well as it should. As a result, air gets trapped in the lungs and the lungs get bigger (hyper-inflated). These changes cause the air sacs (alveoli) to close before you have fully exhaled. ![]() In emphysema, exposure to an irritant over many years causes an inflammation in the lungs which causes the following changes: Please note there is no audio for this animation
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