Shock is a failure of the circulatory system and is a life-threatening medical emergency. Its key feature is inadequate blood flow to vital organs. It is considered a syndrome (a group of signs and symptoms that occur together) and can arise from any of a number of causes. It is usually associated with low blood pressure and decreased urine production.

Common signs and symptoms of shock include the following:

• Low blood pressure, at times undetectable
• Reduced alertness and awareness, confusion, and sleepiness
• Cold, moist, and often bluish and pale hands and feet
• Weak and/or rapid pulse
• Rapid breathing and hyperventilation
• Decreased urine volume
• In septic shock (from overwhelming blood infection)—shaking chills, rapid temperature increase, warm, flushed skin, and rapid pulse
• In shock related to heart problems—lung congestion, rapid pulse, heart murmur, engorged neck veins

Shock can be caused by problems with the heart itself (cardiogenic shock), conditions that block blood flow to or from the heart (extracardiac obstructive shock), severe loss of fluids (hypovolemic shock), or abnormal flow of fluids into the tissues, despite normal or increased heart function (distributive shock).

Heart problems that can cause shock include the following:

• Heart attack (myocardial infarction)
• Rupture of the wall between the heart's ventricles (main pumping chambers)
• Aneurysm (bulging) in a ventricle wall
• Prolonged open heart surgery involving heart/lung bypass
• Dysfunction or inflammation of the heart muscle (cardiomyopathy or myocarditis, respectively)
• Irregular heartbeat, too rapid or too slow
• Defective heart valves, either real or artificial, including narrowing of the aortic valve, leading to decreased blood flow from the heart
• Increased thickness of the wall of one of the ventricles, blocking blood flow out of the heart

Extracardiac obstructive shock can result from the following:

• Pericardial tamponade (buildup of fluid that puts pressure on the heart, preventing it from filling with enough blood)
• Massive pulmonary embolism (blockage of blood flow to the lungs by a blood clot, gas bubble, bit of tissue, or other object)
• Tension pneumothorax (collapse of the lungs caused by air that collects outside them due to a rupture in the lungs or chest wall)
• Severe high blood pressure in the vessels coursing through the lungs

Hypovolemic shock can result from the following:

• Severe bleeding from an injury or disease process
• Severe loss of fluids, as from prolonged vomiting or diarrhea, or from extensive burns
• Diabetes insipidus (a metabolic disorder that causes extreme thirst and urine output)

Distributive shock can result from the following:

• Bacterial infection in the blood (septic shock)
• Drug overdose
• Anaphylaxis (severe, body-wide allergic reaction)
• Abnormal opening of blood vessels due to neurologic dysfunction (neurogenic shock)
• Addisonian crisis (a severe adrenal gland insufficiency) 

The following conditions and characteristics increase the risk for shock:

• Serious injury and trauma
• Heart conditions such as heart disease or heart attack
• Surgery
• Bacterial infection that has spread to the blood
• Bleeding
• Loss of a large volume of fluids from severe diarrhea or vomiting
• Excess alcohol use
• Severe anemia
• Allergic reaction to a drug, food, or environmental exposure
• Drug overdose
• Pregnancy

Shock is an emergency and requires immediate conventional treatment. The healthcare provider will diagnose shock based on your signs and symptoms and any information readily available about underlying disease or recent injury. He or she will check blood pressure, assess mental status (memory, orientation, and alertness), measure urine output and obtain urine cultures, and order blood tests to check heart, lung, and kidney function and search for evidence of sepsis (blood infection). Imaging and other procedures—such as X ray, electrocardiography (ECG), echocardiography—may be performed to check the status of the heart. A heart catheterization may also be used to determine the cause and severity of the individual case of shock.

To help prevent shock, people should have heart disease and other conditions that may predispose them to shock appropriately treated. Those who have severe allergies should avoid allergens that may trigger anaphylactic shock and carry self-injectable epinephrine to treat anaphylaxis.

The main goals of treatment are to maintain blood pressure and to make sure the person's vital organs get enough blood and oxygen. First aid for shock includes laying the person down, raising the legs to help blood return to the heart, stopping any bleeding, ensuring warmth, and performing cardiopulmonary resuscitation (CPR), if needed. Emergency medical staff will administer oxygen and, in the case of hypovolemic and septic shock, intravenous fluids.

The following medications may be used to treat shock:

• Agents to increase pressure in the arteries and increase cardiac output, such as dopamine, dobutamine, and norepinephrine
• Medications to either dilate or constrict the blood vessels (depending on the cause of shock)
• Corticosteroids for anaphylactic shock, to stabilize the patient and prevent recurrence
• Antibiotics for septic shock, to combat wide-ranging infection
• Morphine to dilate veins and decrease anxiety
• Thrombolytic therapy (drugs that dissolve clots as they form) may be considered in the case of myocardial infarction or pulmonary embolism

Depending on the cause of shock, surgery may be required to repair heart valves or rupture of a ventricle, artificially augment blood flow from the heart, or remove an embolism.

Shock is always life-threatening and requires emergency conventional care. Some CAM therapies, however, may be helpful as an adjunct to conventional treatment. For instance, certain nutrients may help protect against the harmful effects of shock and improve the outcome.

Oxidative stress (damage to cells caused by the body's normal use of oxygen) may play a role in shock. Several studies have suggested that treatment with antioxidants that help rid the body of free radicals (harmful by-products of the oxidative process) may protect against some types of shock. Other nutrients may also be protective.

• Carnitine may be helpful in treating cardiogenic, septic, and hypovolemic shock. A study of 115 patients with septic, cardiac, or traumatic shock showed that acetyl-L-carnitine helped improve the conditions of patients with all three types of shock. Improvements included returning heart rate and blood pressure to normal and boosting oxygen delivery throughout the body. L-carnitine has also been reported to prevent cardiogenic shock in people suffering from a heart attack.
• Coenzyme Q10 (CoQ10), an antioxidant, may be beneficial in treating hypovolemic and septic shock. One study of hemorrhagic (bleeding-related) shock in animals showed that CoQ10 helped protect lung function and improve blood flow. A study on animals with septic shock showed that CoQ10 improved heart function, blood flow, and blood pressure; another suggested that pretreatment with CoQ10 improved lung function of the animals who later developed septic shock.
• Glutamine added to parenteral nutrition (nutrients given through the veins when someone cannot take oral nutrition) may protect the intestines and prevent complications from septic shock. This addition of glutamine has been reported to decrease deaths among critically ill patients and is thought to be safe when used along with standard treatment.
• N-acetylcysteine (NAC) improved the immune system response in mice that had septic shock caused by endotoxins (toxins released from bacterial cells). It is not clear what this means for preventing or treating shock in humans.
• Omega-3 Fatty Acids -- Animal studies investigating the role of essential fatty acids in the outcomes from shock show positive effects from omega-3 essential fatty acids and negative effects from omega-6 essential fatty acids. Omega-3 fatty acids appear to fight inflammation, while omega-6 fatty acids appear to promote it. Studies of rats and guinea pigs suggest a diet rich in polyunsaturated omega-3 fatty acids compared with omega-6 fatty acids may protect against the harmful effects of septic shock. Diets of people in the United States and other industrialized countries tend to be high in omega-6 and low in omega-3 fatty acids.
• Vitamins B₃ -- At least two animal studies have suggested that nicotinamide (a form of vitamin B₃) may help protect against bacterial endotoxin that causes septic shock. In one study, mice that were given nicotinamide after being injected with endotoxin were more likely to survive than were mice that did not receive nicotinamide. In another study of rats that had endotoxic shock, blood pressure improved in those that received nicotinamide compared to those that did not receive this supplement.
• Vitamin B₁₂ -- Studies in animals with endotoxic shock suggest that blood pressure may be improved in that clinical situation by taking hydroxocobalamin (a form of vitamin B₁₂).

Plant-based medicines that support the immune system may be beneficial in treating septic shock. For instance, an Ayurvedic formula containing the following ingredients helped reduce the blood levels of bacteria in rats infected with Escherichia coli (an infection that can spread to the bloodstream, potentially causing septic shock) compared to rats that received a placebo:

• Ashwagandha (Withania somnifera)
• Indian gooseberry (Phyllanthus emblica)
• Sweet basil (Ocimum sanctum)
• Tamarisk (Tinospora cordifolia)

A series of newly developed herbal remedies based on traditional Chinese medicine were evaluated for use in 183 people with septic shock. Injections of the following herbs thought to regulate the flow of qi (life energy), appeared to promote blood circulation and help prevent failure of the circulatory system as well as lower the death rate significantly in the treatment group compared to the control group:

• Kangjue tongmai
• Yiqi huiyang
• Yiqi jiuyin 

Scientific studies of homeopathic remedies for the treatment of shock specifically have not been conducted. The remedy Aconite, however, is often used by homeopathic doctors for emergency conditions.

In animals with hypovolemic shock from bleeding, electroacupuncture (small electrical currents applied to acupuncture needles) raised blood pressure, protected cardiac function, and normalized the levels of various protective substances in blood. On the other hand, there have been four case reports of death from shock secondary to acupuncture – one from infection leading to septic shock and the other three caused by bleeding from the heart leading to hypovolemic shock.

In most cases, the outcome of shock depends on receiving immediate and proper treatment. If attended to early, shock is reversible in many cases depending on its cause. Immediate treatment for anaphylactic shock, for example, usually results in complete recovery. But any case of shock is life threatening, regardless of its cause, particularly in the elderly. Shock often causes organ damage (including the kidneys, brain, and liver), cardiac arrest, and respiratory failure.

Those who have suffered from shock will most likely be admitted to intensive care. Following treatment, the healthcare provider will carefully monitor the person's condition, including temperature, blood pressure, cardiac function, urine flow, blood chemistry, and blood cells.

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