Summarize this article in one sentence.
A massive pulmonary embolism (blood clot in the lungs) may be a cause of obstructive shock. It presents with sudden onset chest pain, shortness of breath, and the ensuing signs of shock. A massive PE can be investigated for by getting a TEE (transesophageal echocardiogram) or CT angio of the chest.. This is the fastest way to determine whether one is present and, if so, its exact location. A tension pneumothorax is another possible cause of obstructive shock. It presents with decreased breath sounds on the affected side, a trachea (windpipe) that has deviated from the midline, chest pain and problems breathing. It most commonly occurs in younger individuals following an accident or trauma. However, it can occur in anyone, often after a change in pressure such as an airplane trip. A tension pneumothorax can generally be diagnosed clinically, and treated immediately when it is suspected as the cause of obstructive shock. A cardiac tamponade is when blood pools around the heart, causing a buildup of pressure and a subsequent inability for the heart to effectively pump blood around the body. The more blood that pools, the less effective circulation becomes, which is what leads to the signs and symptoms of shock. A cardiac tamponade often presents with anxiety, sudden chest pain that gets worse with deep breathing or coughing, trouble breathing, lightheadedness and/or fainting, and pale/grey/bluish skin that results from poor circulation. Constrictive pericarditis occurs when the sac around the heart (called the pericardium) becomes inflamed and tightens with scar tissue over time. This, in turn, puts stress on the heart by causing the space in which the heart beats to become more and more enclosed. "Bacterial pericarditis" (an infection of the pericardium - the sac around the heart) may also cause obstructive shock by a similar mechanism. Constrictive pericarditis often presents with trouble breathing, a swollen abdomen as well as swollen legs and ankles (due to the back-up of blood that has trouble getting back into the heart), and chest pain, as well as possible signs of obstructive shock in more severe cases. Aortic stenosis is when the valve that allows blood to exit the heart becomes tightened, blocked, or otherwise compressed, leading to a reduced amount of blood that can effectively leave the heart with each heartbeat. When aortic stenosis becomes very severe, it can lead to obstructive shock by significantly reducing the amount of blood that can exit the heart, and thus reducing blood flow to the body's vital organs. Aortic stenosis often presents with chest pain, lightheadedness and/or fainting, a gradual decrease in exercise tolerance over time, palpitations (the feeling of unusual heartbeats), and a heart murmur that can be heard through a stethoscope. It is a condition that gradually gets worse with time and, in the most severe cases, may lead to the signs and symptoms of obstructive shock.

Summary:
Examine for signs of a massive pulmonary embolism. Evaluate for a possible tension pneumothorax. Watch for symptoms of a cardiac tamponade. Look for "constrictive pericarditis" as a possible cause of obstructive shock. Evaluate for aortic stenosis as a possible cause of obstructive shock.