This weekend, as I drove the five hours to the north Wisconsin woods, I reminded myself of advice I give to my patients: Remember to get out of the car and move around. It's also why, buried deep in the recesses of the in flight magazine, somewhere between the movie grid and the duty-free opportunities, hides a warning that staying still in an airplane seat for a prolonged time can cause blood clots. And while the magazine recommends moving around the cabin and stretching, the flight attendants tend to want to keep you in your seat.
Blood does wonderful things like carrying oxygen, cleaning waste products, and delivering cells and chemicals to fight infection. But mess up its environment and blood can cause all sorts of problems. Blood cells get pushed by the heart to the far recesses of the body, but it returns from the fingers, toes, arms and legs in veins that are milked by the routine contractions of the muscles that surround them. As you walk, blood gets pushed back to the heart; as you type, the muscles of your fingers and hands do the work to get the blood back.
Without that muscle movement, blood stagnates and has a tendency to clot. There are two parallel systems of veins in the legs and arms. The superficial set under the skin drains blood into the deeper set through a set of connectors that have valves in place. So clots in the superficial system are filtered before they enter the deep pipeline. No such luck for the deep vein system. No valve, no filters, and it's a straight shot to the heart and lungs if a clot should form and break off.
Deep venous thrombosis, or DVT, is the medical term for a blood clot in that deeper system. The symptoms of pain, swelling, and redness are similar to those of infection, and sometimes it's hard to tell the two apart, except by using ultrasound to check the flow of blood in the veins. But the DVT is just the harbinger (sign) of potential disaster. If a clot has formed, it can grow and break off and float downstream. Downstream means through the heart and into the lungs, where it can get lodged and make the lungs fail. A clot that breaks free and moves is called an embolus, and a pulmonary (lung) embolus is a big deal and a killer.
Prevention is the key to minimizing the risk of a pulmonary embolism, and knowing the risks allows that prevention to happen. Long car trips, plane travel, being confined to a bed because of injury or illness, having surgery or immobilizing an injured arm or leg are all risks for blood clots. And some unfortunate people were born with an abnormal clotting potential, another risk factor. Doctors and nurses recognize the risk and work hard at getting people moving in the hospital and occasionally give medication to thin or anti-coagulate the blood.
For me and my trip to the wilds of the north woods, the obligation to check out the local diners for pie and coffee was done only for good medical cause and prevention.