DEAR DR. DONOHUE: A young newsman died from one. A former governor is hospitalized for one. What is the prescribed treatment for a pulmonary embolus, and how many people have one? – C.D.

ANSWER: In one year, more than 600,000 Americans and Canadians will have a pulmonary embolus, and of that number, 60,000 will die. It is a common cause of sudden death.

A pulmonary embolus is a blood clot that has traveled to a lung and cut off its blood supply.

The source of pulmonary emboli is usually the deep veins of the legs or the veins of the pelvis. When blood flow through a vein slows to a trickle, the blood clots. That’s a thrombus. A piece of the thrombus breaks off and is carried in the blood to the lungs. That piece is a pulmonary embolus, and, if it is large enough, it can cause death.

Clots in veins form when a person is incapacitated or motionless for a long time. A bedridden patient, for instance, is liable to suffer clot formation in leg veins. So are travelers who have to sit in a seat for four or more hours. Dehydration is another reason why clots form in veins. It was dehydration that most likely caused the pulmonary embolus suffered by the newsman you mentioned.

Prevention of a pulmonary embolus consists in moving the legs at every opportunity. On a long plane ride, walk down the aisle from time to time. On a long car trip, get out of the car and walk about as frequently as possible.

Treatment of a pulmonary embolus consists of administering heparin, a drug that prevents further growth of a clot and development of more emboli. Depending on the situation and the degree of danger that a pulmonary embolus causes, clot-dissolving drugs, similar to those used for a heart attack, can be used.

The best treatment is prevention.

DEAR DR. DONOHUE: Can you shed some light on a Baker’s cyst? It’s a lump on the back of my right knee. There is no severe pain, but it produces a constant ache. What can be done about it? – E.S.

A Baker’s cyst is a behind-the-knee bursa filled with fluid. Bursae are thin, flat discs strategically positioned between tendons and bones to prevent friction when tendons move over the bones. Bursitis is an inflamed bursa that swells with fluid. A Baker’s cyst is, therefore, a kind of bursitis.

In adults, Baker’s cysts form most often when there is trouble with the knee joint. The joint and the bursa are connected by a tunnel that has a one-way valve. Fluid from the knee joint can pass into the bursa but cannot return to the joint because the one-way valve closes.

Resting the knee and taking anti-inflammatory medicines such as Aleve can sometimes bring down the swelling.

A doctor can drain the cyst with a syringe and needle and then inject cortisone to prevent repeat fluid accumulation. Frequently the doctor will inject the knee, since that is the ultimate source of swelling.

Finding what’s wrong with the knee and treating that is the long-term answer to a Baker’s cyst.

DEAR DR. DONOHUE: My 6-year-old son has Perthes disease. He has started physical therapy and wears a brace. Can you tell me what the future holds for him due to Perthes disease? – B.H.

Why Perthes disease happens is up in the air. What happens, however, is known. There is an interruption to blood supply to the top of the thigh bone, the femur. That bloodless part of bone fissures and crumbles.

It happens to children mostly between the ages of 2 and 12. Your son is fortunate in one respect. The earlier in life that Perthes occurs, the better are the child’s chances for complete healing without any consequences – such as arthritis – later in life. The future for your child looks good.

This illness is often called Legg-Calvé-Perthes disease, to credit all three physicians who were the first to describe it.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475.

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