By Peggy O'Farrell
The Cincinnati Enquirer

Experts say NBC newsman David Bloom's death Sunday from a pulmonary embolism demonstrates how widespread and deadly blood clots can be.

Bloom, 39, was traveling with the U.S. Army's 3rd Infantry Division in Iraq. He was about 25 miles south of Baghdad and packing gear when he collapsed. He never regained consciousness.

Bloom rode in a specially equipped vehicle, and that travel, coupled with dry desert conditions, might have contributed to his death, experts speculate. Pulmonary embolism kills about 650,000 Americans a year. It is the third leading cause of death in the United States.

Dr. Amy Reed, a vascular surgeon at University Hospital, discussed blood clots and pulmonary embolism:

Question: How do blood clots form?

Answer: A clot forms in the veins, and it most often occurs when people have been sedentary or after surgery or a transatlantic flight, when there can be poor return of circulation to the heart, and blood can pool in the legs.

When the blood pools, there's more opportunity for a clot to form. When it forms in the legs, that's called a venous thrombosis.

Q: What's a pulmonary embolism?

A: If untreated, a blood clot can, one, get bigger so it spans a farther distance, from the knee into the thigh, for instance, or, two, a piece of it can break off or the whole thing can travel through the vein up into the heart.

When it travels up to the right side of the heart where the venous blood goes, that clot can plug up the vein that goes from the heart to the lung. That's called a pulmonary embolism.

If that happens, blood can't get into the lung and the heart fails, because there's no blood going to the lung and no blood coming back into the heart.

Q: What are the warning signs of blood clots?

A: There's a risk of blood clots after surgery because patients are immobilized, so (hospitals) take precautions. A long car ride or airplane flight, or anything where they're sedentary, is also a risk. Dehydration can add to that.

Symptoms are swelling in the leg that develops suddenly and pain along with the swelling. Those would be the main signs for a clot that's isolated to the leg. If there's a risk that (a clot) has traveled to the heart, the person might feel difficulty breathing.

They might feel pain when they take a breath, or occasionally, a person feels an impending sense of doom.

Q: Are there risk factors other than being sedentary for blood clots?

A: Certain congenital or hereditary abnormalities that affect clotting can predispose a person to develop a clot. Someone might have a history of blood clots. Birth control pills and smoking also contribute to blood clots.

Q: How do you diagnose and treat a blood clot?

A: If it's in a vein in the leg, we usually use an Ultrasound. A technologist can look at the veins and compress the blood vessels to detect the presence of a clot.

We treat it with anticoagulants, starting with a shot and then switching to pills.

If it's in the lung, that's much more of an acute situation. Most of those people we're seeing in the emergency room. We diagnose it using a CT scan.

Once we find an embolism, if the patient is stable, we treat it with blood thinners, usually in IV form, and then switch to pills. If they're (more serious), having problems with blood pressure and breathing, there are other clot-busting agents that can be given to break up the clot and help blood get to the lung. Very rarely the person will have surgery to have the clot removed.

E-mail pofarrell@enquirer.com