An embolism
in a medical context refers to any large moving mass or defect in the
blood stream. An air embolism is an air bubble trapped in a blood
vessel. When an air bubble travels along an artery, it moves through a
system of blood vessels that gradually become narrower. At some point,
the embolus will block a small artery and cut off the blood supply to a
particular area of the body.
For example, when a person scuba dives with compressed air, they take in extra oxygen and nitrogen. The body uses the oxygen, but the nitrogen is dissolved into the blood, where it remains during the dive. As one swims back toward the surface after a deep dive, the water pressure around decreases. If this transition occurs too quickly, the nitrogen does not have time to clear from the blood. Instead, it separates out of the blood and forms bubbles within tissues or blood. It is these nitrogen bubbles that cause decompression sickness.
For venous air embolisms, death may occur if a large bubble of gas becomes lodged in the heart, stopping blood from flowing from the right ventricle to the lungs. However, experiments in animals show that the amount of gas necessary for this to happen is quite variable, and also depends on several other factors, such as body position.
According to Medilexicon's medical dictionary:
The word "embolus" comes from the Greek "embolos" meaning a wedge or plug. "Embolos" was derived from "en" (in) + "ballein" (to throw) so an embolus is something thrown in.
Symptoms of decompression sickness include joint pain, dizziness, extreme fatigue, tingling or numbness, weakness in arms or legs, skin rash and unconsciousness or paralysis in severe cases.
In particular, a large air embolism in the arteries to the brain will cause immediate loss of consciousness and often causes convulsions. It may also cause a stroke.
In the heart, an air embolism in the coronary arteries (which lead to the heart) will cause a heart attack. A heart attack can also be caused by a large air embolism in the arteries to the brain.
Finally, an embolism in a blood vessel to the lungs (pulmonary embolism) causes chest pain and shortness of breath.
Pulmonary barotrauma happens when divers run out of air and, in a panic, hold their breath while rapidly swimming to the surface. As they come up and the pressure around them decreases, the air in their lungs expands. The expanding air causes the lungs to overinflate, which can rupture the alveoli (tiny air sacs in the lungs). Air can escape from the lungs and enter the blood vessels, which can cause an air embolism.
Air embolism can happen in as little as one meter of water, if the diver is breathing compressed air and holds their breath while rapidly surfacing.
Trauma to the lung can also cause an air embolism. This may happen after a patient is placed on a ventilator and air is forced into an injured vein or artery, causing sudden death.
Air embolism can occasionally occur during surgery to the blood vessels or large blood transfusions, if a large quantity of air is mistakenly injected into the vessels (although doctors are trained to remove excess air from a syringe before giving injections).
Monitoring patients during surgery is also very effective to identify potential embolism. First, a transesophageal echocardiography, a tiny scanner on the end of a thin tube is inserted into the body through the mouth and down the airway, monitors the heart with ultrasound and detects relatively small air bubbles that may form.
A second monitoring option Pulmonary artery catheter, which is a tiny tube inserted into the artery connecting the heart to the lungs and blood pressure is monitored. A change in blood pressure shows that an air embolism may be present.
If an air embolism is suspected during surgery, the surgeon will prevent more air from entering the body by sealing the open blood vessels. They may also reduce the amount of air already in the body using a hyperbaric oxygen chamber.
A fall in blood pressure can be prevented by introducing fluids. Drugs, such as adrenaline, will keep the heart functioning. If possible, the site of the operation should be positioned lower than the level of the heart, by repositioning the person or tilting the operating table.
Do not fly within 24 hours after diving. Don't drink alcohol before diving. Avoid hot tubs, saunas or hot baths after diving. Make sure a diver is well hydrated, well rested and prepared before a dive.
Some people should avoid diving altogether, or should consider special risks. If a person has a heart defect, it is not safe to dive. A person who requires insulin to treat diabetes may have wide swings in blood glucose levels during a dive, and caution is advised. One should avoid diving if you have a groin hernia that has not been repaired, since expanding gas in the hernia can cause symptoms.
For example, when a person scuba dives with compressed air, they take in extra oxygen and nitrogen. The body uses the oxygen, but the nitrogen is dissolved into the blood, where it remains during the dive. As one swims back toward the surface after a deep dive, the water pressure around decreases. If this transition occurs too quickly, the nitrogen does not have time to clear from the blood. Instead, it separates out of the blood and forms bubbles within tissues or blood. It is these nitrogen bubbles that cause decompression sickness.
For venous air embolisms, death may occur if a large bubble of gas becomes lodged in the heart, stopping blood from flowing from the right ventricle to the lungs. However, experiments in animals show that the amount of gas necessary for this to happen is quite variable, and also depends on several other factors, such as body position.
According to Medilexicon's medical dictionary:
An Air Embolism is an embolism caused by air bubbles in the vascular system; venous air embolism can result from the introduction of air through intravenous lines, especially central lines, and generally must be substantial to block pulmonary blood flow and cause symptoms; arterial air embolism is also usually iatrogenic, caused by cardiopulmonary bypass or other intravascular interventions, occurs rarely after penetrating lung injury; small amounts of arterial air can cause death by blockage of coronary and/or cerebral arteries; small bubbles introduced into the venous system may similarly cause symptoms if they reach the arterial side.
The word "embolus" comes from the Greek "embolos" meaning a wedge or plug. "Embolos" was derived from "en" (in) + "ballein" (to throw) so an embolus is something thrown in.
What are the symptoms of An Air Embolism?
A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom while dilated pupils may be a sign.Symptoms of decompression sickness include joint pain, dizziness, extreme fatigue, tingling or numbness, weakness in arms or legs, skin rash and unconsciousness or paralysis in severe cases.
In particular, a large air embolism in the arteries to the brain will cause immediate loss of consciousness and often causes convulsions. It may also cause a stroke.
In the heart, an air embolism in the coronary arteries (which lead to the heart) will cause a heart attack. A heart attack can also be caused by a large air embolism in the arteries to the brain.
Finally, an embolism in a blood vessel to the lungs (pulmonary embolism) causes chest pain and shortness of breath.
What are the causes of An Air Embolism?
Air embolism can occur whenever a blood vessel is open and a pressure gradient exists favoring entry of gas. Because the pressure in most arteries and veins is greater than atmospheric pressure, an air embolus does not always happen when a blood vessel is injured.Pulmonary barotrauma happens when divers run out of air and, in a panic, hold their breath while rapidly swimming to the surface. As they come up and the pressure around them decreases, the air in their lungs expands. The expanding air causes the lungs to overinflate, which can rupture the alveoli (tiny air sacs in the lungs). Air can escape from the lungs and enter the blood vessels, which can cause an air embolism.
Air embolism can happen in as little as one meter of water, if the diver is breathing compressed air and holds their breath while rapidly surfacing.
Trauma to the lung can also cause an air embolism. This may happen after a patient is placed on a ventilator and air is forced into an injured vein or artery, causing sudden death.
Air embolism can occasionally occur during surgery to the blood vessels or large blood transfusions, if a large quantity of air is mistakenly injected into the vessels (although doctors are trained to remove excess air from a syringe before giving injections).
Diagnosing An Air Embolism
Diving history and symptoms are key factors in diagnosing decompression sickness. Divers should always be carefully monitored by their colleagues and supervisors so that if an air embolism occurs, it can be immediately identified and treated. If a scuba diver loses consciousness within 10 minutes of surfacing, they probably have an air embolism and should be treated immediately.Monitoring patients during surgery is also very effective to identify potential embolism. First, a transesophageal echocardiography, a tiny scanner on the end of a thin tube is inserted into the body through the mouth and down the airway, monitors the heart with ultrasound and detects relatively small air bubbles that may form.
A second monitoring option Pulmonary artery catheter, which is a tiny tube inserted into the artery connecting the heart to the lungs and blood pressure is monitored. A change in blood pressure shows that an air embolism may be present.
What are the treatment options for An Air Embolism?
Most diving cases of decompression sickness respond well to a single treatment with hyperbaric oxygen. Additionally, according to Boyle's law, the size of the gas bubble or bubbles decreases in proportion to the increase in atmospheric pressure. In the hyperbaric chamber the patient breathes 100% oxygen. Under hyperbaric conditions, oxygen diffuses into the bubbles, displacing the nitrogen from the bubble and into solution in the blood.If an air embolism is suspected during surgery, the surgeon will prevent more air from entering the body by sealing the open blood vessels. They may also reduce the amount of air already in the body using a hyperbaric oxygen chamber.
A fall in blood pressure can be prevented by introducing fluids. Drugs, such as adrenaline, will keep the heart functioning. If possible, the site of the operation should be positioned lower than the level of the heart, by repositioning the person or tilting the operating table.
Preventing An Air Embolism
Taking special care when diving is the best way to prevent the most common causes of embolism. Dive and rise slowly in the water, and don't stay at the deepest depth longer than recommended. Scuba divers typically use dive tables that show how long one can remain at a given depth.Do not fly within 24 hours after diving. Don't drink alcohol before diving. Avoid hot tubs, saunas or hot baths after diving. Make sure a diver is well hydrated, well rested and prepared before a dive.
Some people should avoid diving altogether, or should consider special risks. If a person has a heart defect, it is not safe to dive. A person who requires insulin to treat diabetes may have wide swings in blood glucose levels during a dive, and caution is advised. One should avoid diving if you have a groin hernia that has not been repaired, since expanding gas in the hernia can cause symptoms.
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