Gas embolism

Generality

Air embolism is a pathological state in which an air bubble obstructs the normal flow of blood within a vessel.

Graphic representation of a series of air bubbles inside a vessel. Note how the larger embolus completely obstructs the passage of blood.

From the site: safeinfusiontherapy.com

A gas bubble can enter the bloodstream from a "poorly performed venous injection," risky scuba diving, surgery, a blow to the chest, etc.
The symptoms are very diverse and strongly depend on which blood vessels are blocked by the gas bubble. The most serious complications occur when the air embolism causes a stroke, heart attack, or respiratory failure.
For a correct diagnosis, the doctor first of all resorts to a physical examination and an analysis of the patient's medical history.
Therapy depends on the severity and causes of the embolism.

What is gas embolism?

Air embolism is a pathological condition that arises when one or more air bubbles block the flow of blood within a blood vessel.
If the affected vessel is an "artery, we speak of an arterial gas embolism; if a vein is involved, we speak of a venous gas embolism.

MEANING OF EMBOLIA AND AIR BUBBLES

The term embolism identifies any presence, inside the blood vessels, of a mobile body unable to dissolve in the blood. This body, generically called an embolus, can be a blood clot, a lump of fat, an air bubble, etc.

Emboli are carried by the blood to a certain point, where they stop, partially or totally blocking blood circulation.
Air bubbles therefore have all the typical characteristics of emboli; consequently, moving within the vascular system, they can reach any part of the body and obstruct blood circulation.

HOW DANGEROUS IS A GASEOUS EMBOLIA?

The presence of air bubbles circulating in the vascular system can be very dangerous, as the emboli could also reach the arteries of the brain, the coronary arteries that supply the heart muscle and the blood vessels that carry deoxygenated blood from the heart to the lungs.

If the air bubbles end up in the arterial vessels of the brain, they could cause a stroke (embolic ischemic type).
If the bubbles reach the coronary arteries, it could lead to a heart attack.
If the bubbles enter the pulmonary artery or one of its branches (pulmonary embolism), they could cause respiratory failure.

EPIDEMIOLOGY

The exact incidence of gas embolism is unknown; however it is a very rare pathological condition.
Air embolism is a leading cause of death among divers (divers).

Causes

Gas bubbles form inside the vascular system when the pressure conditions around a blood vessel exposed to a gas favor the latter's entry into the vessel. In other words, if an artery or vein they are in contact with the air and the surrounding pressure conditions allow it, atmospheric gases can penetrate the vessel involved and form bubbles.
The formation of one or more air bubbles inside a blood vessel can occur when:

Injections. If misused, syringes used for venous injections can lead to the introduction of air into the vascular system.
Air embolism due to injections is very rare.
Surgical procedures. During some surgical operations, we resort to the use of central venous catheters in the subclavian or jugular vein. Since in these regions the pressure conditions favor the entry of air into the vascular system (NB: venous pressure is lower than atmospheric pressure) , the introduction of a catheter could represent a gateway for atmospheric gases. To try to prevent this inconvenience, doctors insert the catheter by positioning the patient supine and with the head sloping down with respect to the bed (Trendelenburg position).
The surgeries most at risk of air embolism are brain surgery; according to an accredited scientific journal, the Journal of Minimal Access Surgery, 80% of brain procedures cause the formation of a gas embolism, which, however, is then eliminated by doctors before finishing the operation.
Trauma to the lungs. After a chest injury that damages the lungs, artificial ventilation may be required. If the trauma involved a vascular injury, the air introduced with artificial ventilation could seep into the injured vessel and form bubbles.
Scuba diving. If a diver remains underwater for too long, he accumulates a lot of nitrogen in his blood and tissues, as nitrogen is contained in the air of the breathing cylinders.
The presence of large doses of nitrogen and the failure to eliminate nitrogen can lead to the formation of gas bubbles in the blood or tissues. This process is also known as decompression sickness.
N.B: decompression sickness can also arise as a result of "exposure to high pressures, for example when diving into the depths of the sea."
Pulmonary barotrauma. Barotrauma is any injury caused by a pressure difference between the air contained in a body cavity and the environment surrounding that cavity. If a barotrauma occurs in the lungs (pulmonary overdistension or pulmonary barotrauma), it could happen that the pulmonary alveoli are injured and the air breathed thereafter enters the arterial vessels, giving rise to an arterial gas embolism.
The main cause of pulmonary barotrauma is surfacing too fast during a scuba dive.
Bomb explosion. A person located near where a bomb explodes is subjected to a sudden surge in pressure, which can lead to the injury of certain organs and tissues in contact with the air, such as the ears, alveoli or the first part of the digestive system. . Under such conditions, it is possible to develop a "gas embolism."
Sexual intercourse (in women). If the vagina, uterus or placenta has a small lesion, it is possible for air to enter the damaged vessels during sexual intercourse (especially oral sex).
Air embolism following sexual intercourse is more common among pregnant women, as they may have small sores on the placenta.

Symptoms

The gas embolism does not always present itself with the same symptoms: some patients, in fact, suffer from minor complaints or do not suffer at all; while others show serious problems.
Depending on where the air bubbles are located, the symptoms and signs of air embolism could be:

Dyspnea on exertion and dyspnea at rest. The so-called "air starvation" is typical of cases in which the air bubbles are found in the pulmonary artery or in one of its branches (pulmonary embolism).
Palpitations, chest pain, cough and coughing up blood (hemoptysis). They are typical disorders of pulmonary embolism.
Cyanosis. It is a characteristic sign of pulmonary embolism.
Lightheadedness and dizziness
Fainting
Nausea and vomit
Excessive sweating
Hypotension
Generalized feeling of tiredness
Irregular heartbeat and tachycardia. It can arise either from a pulmonary embolism or from air bubbles in the heart.
Mental confusion, cognitive impairment and personality changes. They are typical of when the air bubbles have reached the brain (embolic ischemic stroke)
Paralysis, a sense of weakness, loss of coordination and numbness. These are all signs of an embolic ischemic stroke.
Visual difficulties. Typical of embolic ischemic stroke.
Loss of consciousness
Convulsions
Tremors
Acoustic problems
Altered tactile perception
Dizziness

TYPICAL SYMPTOMS OF GASEOUS EMBOLIA ASSOCIATED WITH DISEASE DECOMPRESSION

Some factors favoring decompression sickness in divers:

Patent foramen ovale (heart defect)
Cold water
Dehydration
Obesity
Fly a few hours after diving
Old age
Push yourself too deep
Being too underwater
Perform multiple dives in the same day

Typical symptoms of air embolism associated with decompression sickness are as follows: dizziness, blurred vision, bleeding from the mouth, paralysis, feeling of weakness, convulsions, unconsciousness and shortness of breath.

WHEN TO SEE THE DOCTOR?

If a person complains of a symptomatological picture similar to the one reported above, it is better to go to a hospital immediately. In fact, if it is severe, the gas embolism requires prompt medical intervention, because otherwise it could lead to death.

COMPLICATIONS

Among the possible complications, there are the most serious consequences of stroke (total paralysis of the motor muscles, severe difficulty in speaking and swallowing, memory loss, etc.), heart attack (ventricular fibrillation, severe heart failure, etc.) and pulmonary embolism (severe respiratory failure and pulmonary hypertension).

Diagnosis

To diagnose a "gas embolism, the following are of fundamental importance:

The physical examination, during which the doctor analyzes and evaluates the symptoms accused by the patient.
The examination of the medical history, which is used by the physician to establish what may have triggered the onset of the current disorders. For example, the fact that, before the onset of symptoms, the patient suffered a blow to the chest could be a "important information; as well as frequent diving or having performed autonomously (incorrectly) a" venous injection of some drug.
The Doppler. The Doppler allows to analyze in real time the anatomical and functional situation of the blood vessels. It then clarifies what is the exact dynamics of the vascular blood flow and if, inside the vessels, there are occlusions or obstacles (including air bubbles). This is a completely bloodless procedure.
CT scan (or computerized axial tomography). The CT scan is able to detect abnormalities and occlusions that could affect blood vessels. It is considered an invasive examination, as it exposes the patient to a minimal dose of ionizing radiation.

HOW TO NOTICE THE PRESENCE OF AIR BUBBLES DURING SURGICAL INTERVENTIONS?

To understand if air bubbles have formed during surgery, doctors constantly monitor the patient's following parameters: frequency and characteristics of breathing (particular noises, etc.), blood pressure, heart rate and particular noises emitted by the patient. heart.
Diagnosing a "post-surgical gas embolism in time" is crucial to avoiding unpleasant consequences.

Treatment

Usually, small air bubbles dissolve in the bloodstream completely spontaneously. However, it is very important to immediately remedy the causes that caused them to form, in order to prevent others from forming.
If the gas bubbles are large, or the causes of gas embolism are particularly severe, things are more complicated. In these situations, in fact, it may be necessary to resort to surgery to remove the bubbles or to hyperbaric oxygen therapy.

WHAT TO DO IF THE GASEOUS EMBOLIA HAS TAKEN PLACE AFTER A DIVE? NOTES OF UNDERWATER MEDICINE

If the air embolism occurs following a scuba dive, it is necessary to:

Have the patient lie down with the head lower than the feet (Trendelenburg position) and the body turned to the left side
Give him oxygen
Take him to a hospital with a hyperbaric chamber as soon as possible (hyperbaric oxygen therapy).

IPERBARIC ROOM

The hyperbaric chamber (or hyperbaric therapy chamber) is a room inside which it is possible to breathe 100% pure oxygen at a pressure higher than normal.

Trendelenburg position. Putting the patient in this position is useful not only in case of post-dive gas embolism, but also before inserting a central venous catheter in the subclavian or jugular. From the site: wikipedia.org

The session usually lasts a couple of hours: this time is used to restore normal blood pressure (which after a dive could be altered) and to eliminate any air bubbles present in the body.
At the end of the treatment, it is important that the pressure inside the chamber is gradually restored to normal. If, in fact, the return to normal pressure levels is sudden, it is likely that the patient is affected (N.B: it is the same situation in which a diver finds himself rising to the surface too quickly).

Prevention

To prevent a dive from becoming life-threatening, it is a good idea to:

Limit the time spent underwater, so as not to accumulate too much nitrogen in the blood and tissues.
Avoid going too deep, because the deeper you go into the sea, the higher the pressure and the greater the risk of gas embolism.
Avoid diving if you suffer from cold, cough or some chest affection at that time.
In the 12-24 hours after surfacing, do not travel by plane and do not travel to high altitudes.
Come up to the surface slowly.