Embolism: Embolism is movement of some form of particles or air from one part of the blood circulation to another part, causing obstruction to the circulation. Most often it is a blood clot that moves in the circulation (thromboembolism). But rarely it could be fat (fat embolism) or air (air embolism).

What are the important types of embolism according to organs affected?

If blood vessels of the brain are blocked by blood clots traveling from another part of the circulation, it is called cerebral embolism. Cerebral embolism results in loss of function of the region controlled by that part of the brain, usually resulting in a stroke with paralysis of one or more limbs.

Embolism can occur to the blood vessels of the heart. Then it is called coronary embolism, which can result in a heart attack.

If it is to a blood vessel of the limbs, it is called peripheral embolism. If blood supply to a limb is blocked that limb can get severely damaged due to lack of blood supply (gangrene). It is an extremely painful and potentially life threatening condition.

Blockage of blood vessels of the kidney is called renal embolism and that of the intestine mesenteric embolism.

What is air embolism?

If a large quantity of air enters the blood vessels, it can cause an air lock in the right ventricle. This causes almost total stoppage of blood circulation and the heart stops functioning. Unless it is promptly removed, it is immediately fatal. If the heart stops functioning immediate cardiopulmonary resuscitation (CPR) is begun. This may partly break off the air in the right ventricle and occasionally relieve the airlock. Sometimes it may be possible to aspirate the air out. But all these are often not easy because the time available is very limited.

If small quantities enter the circulation and reaches one of the organs, it can cause air lock in small blood vessels of the organ and its function is impaired. If it reaches the brain, brain function will be disturbed. If it reaches the blood vessels of the heart, chest pain and fall in blood pressure can occur. Breathlessness can occur if air reaches the blood vessels of the lung resulting in fall in oxygen saturation of blood. Such cases can be treated by giving high flow oxygen using an oxygen mask. It may be noted that when air reaches the circulation, the oxygen in it gets dissolved in blood, but the nitrogen remains, causing the airlock.

What is fat embolism?

Liquid fat can from the bone marrow can enter the circulation when there is a fracture of large bones. This travels and blocks small blood vessels of the lungs and brain. Blockage of blood vessels of the lung causes breathlessness and fall in oxygen saturation of blood. Blockage of blood vessels of the brain decreases the level of consciousness and alteration in behaviour. Small blood vessels of skin can also be affected, which manifests as multiple reddish spots on the body. These may also be seen inside the eyelids. Immediate treatment is by giving high flow oxygen inhalation. Sometimes artificial ventilation using a mechanical ventilator may be needed if oxygen level in the blood cannot be maintained well by oxygen inhalation.