Air embolism and veins is greater than atmospheric pressure, an air embolus does not often happen when a blood vessel is injured. In the veins above the heart, such as in the head and neck, the venous pressure may be less than atmospheric and an injury may let air in. This is one reason why surgeons must be particularly careful when operating on the brain, and why the head of the bed is tilted down when inserting or removing a central venous catheter from the jugular or subclavian veins. When air enters the veins, it travels to the right side of the
Varicose veins is returned by the deep veins, the superficial veins, which return only about 10% of the total blood of the legs, can usually be removed or ablated without serious harm. Secondary varicose veins are those developing as collateral pathways, typically after stenosis or occlusion of the deep veins, a common sequel of extensive deep venous thrombosis (DVT). Treatment options are usually support stockings, occasionally sclerotherapy and, rarely, limited surgery. Varicose veins are distinguished from reticular veins (blue veins) and spider veins, which also involve valvular insufficiency, by the size and location of the veins. Many patients who suffer with varicose