Arterial emboli are usually a complication of heart disease where blood clots form in the heart's chambers. Gas emboli are caused by rapid changes in environmental pressure that could happen when flying or scuba diving. A pulmonary embolism is caused by blood clots that travel through the blood stream to the lungs and block a pulmonary artery. More than 90% of the cases of pulmonary embolism are a complication of deep vein thrombosis, which typically occurs in patients who have had orthopedic surgery and patients with cancer or other chronic illnesses like congestive heart failure.

Risk factors for arterial and pulmonary emboli include: prolonged bed rest, surgery, childbirth, heart attack, stroke, congestive heart failure, cancer, obesity, a broken hip or leg, oral contraceptives, sickle cell anemia, chest trauma, certain congenital heart defects, and old age. Risk factors for gas emboli include: scuba diving, amateur plane flight, exercise, injury, obesity, dehydration, excessive alcohol, colds, and medications such as narcotics and antihistamines.

Symptoms of an arterial embolism include:

• severe pain in the area of the embolism
• pale, bluish cool skin
• numbness
• tingling
• muscular weakness or paralysis

Common symptoms of a pulmonary embolism include:

• labored breathing, sometimes accompanied by chest pain
• a rapid pulse
• a cough that may produce sputum
• a low-grade fever
• fluid build-up in the lungs

Less common symptoms include:

• coughing up blood
• pain caused by movement or breathing
• leg swelling
• bluish skin
• fainting
• swollen neck veins