This is the first of two articles devoted to a discussion on pulmonary embolism (PE). The lungs have a number of functions beyond oxygenating our blood. One function you probably did not know is that the lungs act as a sieve to remove small, sometimes microscopic clots (emboli) from our blood stream.

We are always forming small emboli in our bodies most of which come from the venous system. Here’s a brief anatomy lesion. Tiny blood clots may be generated in our veins. Our veins send blood to the right side of our heart. The right side of the heart pumps the blood to the blood vessels and capillaries of the lungs. It is in those capillaries that the small, microscopic clots (emboli) are trapped and then dissolved by our own body. This trapping of small, microscopic clots does not interfere with the overall function of the lung’s oxygenation of our blood. However, when the clots are large this is not the case. Large clots which are trapped in the circulation of the lungs can cause problems with oxygenation as well as pressures inside the lung’s blood vessels.

Large clots being trapped in the lungs is a serious and often life threatening event. The body’s ability to dissolve a large clot does not occur in a short period of time. Therefore, patients with large clots in their lungs (pulmonary emboli or PE) can have difficulty for days, suffering pain, shortness of breath, cardiac decompensation and possibly sudden death