Air Embolism

Blood vessels are free of air bubbles or any other substances that can potentially block an artery. Air embolism is a situation in which an air bubble (embolus) gets trapped inside a vessel, and subsequently blocks an artery. Depending on the size of the embolus, a variety of complications may occur, ranging from heartache to death! The seriousness of the condition depends on which part of the body is related to the blocked artery. Fatalities may occur if the artery carrying blood to brain is blocked, causing stroke, seizures or loss of consciousness.

                Causes: Air embolism usually occurs in scuba divers when they run out of air, or hold breath while coming out of the water. Other causes include surgeries, injury to chest in accidents, injury to lungs due to change in pressure and improper blood transfusions when large amount of air is transferred by mistake via the syringe. These are rare however. Oral sex during pregnancy and fractured catheters may also induce air embolism. For embolism to occur, there must be a direct exposure of vessels to the air source, and a pressure gradient allowing air passage into circulation must be present.

                Symptoms: The symptoms vary depending on site of blockage. Embolism in artery leading to brain is the most severe, as the brain cells die due to lack of oxygen. This causes permanent damage, and at a lesser degree, may lead to strokes, fits and loss of consciousness. Blockage of coronary arteries leads to heart attacks and severe chest pain. Blockage of pulmonary artery caused shortness of breath. Fatigue, blurred vision, reduced blood pressure, irregular heartbeat, cyanosis (development of bluish skin tone), weakness and dizziness are other symptoms characterizing air embolism.

                Diagnosis: Divers must undergo regular tests and physical examination to avoid complications. Patients undergoing surgery must be monitored to avoid risks. Trans esophageal echocardiography is performed to detect small air bubbles. Doppler ultrasound is used to monitor blood flow speed and changes in density of blood, during surgeries related to nervous system. A pulmonary artery catheter is used to monitor the artery connecting heart and lungs to detect blood pressure changes that may indicate embolism. Accurate diagnosis of air embolism is complicated. Laboratory tests, hemodynamic analysis and chest x-ray findings are helpful in prognosis.

                Treatment: The most appropriate treatment of air embolism is recompression in a hyperbaric oxygen chamber, which reduces the size of air bubbles, thereby restoring normal blood flow. Decrease in blood pressure is prevented by increase in fluid intake. Use of mechanical ventilation, volume resuscitation further manages the condition. Air embolism in arteries leading to brain is usually treated with barbiturates.

                Prevention: Divers must take special precaution as most cases of air embolism occur during scuba diving. In case of surgeries, the patient should be carefully monitored to avoid any inadvertent development of embolism. Intravenous syringes should be thoroughly checked for air bubbles before insertion.