Shock (circulatory)
Shock is the state of insufficient blood flow to the tissues of the body as a result of problems with the circulatory system. Initial symptoms of shock may include weakness, fast heart rate, fast breathing, sweating, anxiety, and increased thirst. This may be followed by confusion, unconsciousness, or cardiac arrest, as complications worsen.
| Shock | |
|---|---|
| US Navy EMT trainees and firemen using IV fluid replacement in treating a trauma training mannequin to prevent hypovolemic shock. | |
| Specialty | Critical care medicine |
| Symptoms | Initial: Weakness, fast heart rate, fast breathing, sweating, anxiety, increased thirst Later: Confusion, unconsciousness, cardiac arrest |
| Types | Low volume, cardiogenic, obstructive, distributive |
| Causes | Low volume: Severe bleeding, vomiting, diarrhea, dehydration, or pancreatitis Cardiogenic: severe heart attack (especially of the left or right ventricles), severe heart failure, cardiac contusion Obstructive: Cardiac tamponade, tension pneumothorax Distributive: Sepsis, spinal cord injury, certain overdoses |
| Diagnostic method | Based on symptoms, physical exam, laboratory tests |
| Treatment | Based on the underlying cause |
| Medication | Intravenous fluid, vasopressors |
| Prognosis | Risk of death 20 to 50% |
| Frequency | 1.2 million per year (US) |
Shock is divided into four main types based on the underlying cause: hypovolemic, cardiogenic, obstructive, and distributive shock. Hypovolemic shock, also known as low volume shock, may be from bleeding, diarrhea, or vomiting. Cardiogenic shock may be due to a heart attack or cardiac contusion. Obstructive shock may be due to cardiac tamponade or a tension pneumothorax. Distributive shock may be due to sepsis, anaphylaxis, injury to the upper spinal cord, or certain overdoses.
The diagnosis is generally based on a combination of symptoms, physical examination, and laboratory tests. A decreased pulse pressure (systolic blood pressure minus diastolic blood pressure) or a fast heart rate raises concerns. The heart rate divided by systolic blood pressure, known as the shock index (SI), of greater than 0.8 supports the diagnosis more than low blood pressure or a fast heart rate in isolation.
Treatment of shock is based on the likely underlying cause. An open airway and sufficient breathing should be established. Any ongoing bleeding should be stopped, which may require surgery or embolization. Intravenous fluid, such as Ringer's lactate or packed red blood cells, is often given. Efforts to maintain a normal body temperature are also important. Vasopressors may be useful in certain cases. Shock is both common and has a high risk of death. In the United States about 1.2 million people present to the emergency room each year with shock and their risk of death is between 20 and 50%.