Foreign body. Atelectasis is common in children who have inhaled an object, such as a peanut or small toy part, into their lungs. Narrowing of major airways from disease. Chronic infections, including fungal infections, tuberculosis and other diseases, can scar and constrict major airways. Tumor in a major airway.
He'll be placed on blood thinners to break up the clots...which can take from days to weeks. This is also a very dangerous time for him, as a clot could travel and lodge in a coronary artery on his heart, causing a heart attack, or it could travel and lodge in an artery in his brain causing a stroke.
Typically, your body breaks down the clot. However, sometimes blood clots form too easily or do not dissolve properly. This excessive clotting -- hypercoagulation -- also causes thick blood. This can be dangerous since clots can form inside your blood vessels and block blood flow to tissues or organs.