shock Shock refers to the acute systemic pathological process in which the effective circulating blood volume sharply decreases, tissue blood perfusion is severely inadequate, and cellular ischemia and hypoxia occur due to the strong pathogenic factors such as severe blood or fluid loss, infection, and trauma, leading to functional, metabolic disorders, and structural damage in vital organs. The sharp decrease in microcirculatory perfusion and cellular damage in the body's tissues are the main characteristics of shock.

Shock refers to the acute systemic pathological process in which the effective circulating blood volume sharply decreases, tissue blood perfusion is severely inadequate, and cellular ischemia and hypoxia occur due to the strong pathogenic factors such as severe blood or fluid loss, infection, and trauma, leading to functional, metabolic disorders, and structural damage in vital organs. The sharp decrease in microcirculatory perfusion and cellular damage in the body's tissues are the main characteristics of shock.

Classification by etiology

There are hemorrhagic shock, burn shock, traumatic shock, septic shock, anaphylactic shock, cardiogenic shock, and neurogenic shock, among others.

Classification by initiating factors

It can be divided into hypovolemic shock, vasogenic shock, and cardiogenic shock.

Classification by hemodynamic characteristics

It can be divided into hypovolemic shock, cardiogenic shock, obstructive shock, and distributive shock.

Hemorrhage

Common in traumatic bleeding, gastric ulcer bleeding, esophageal variceal bleeding, ectopic pregnancy, postpartum hemorrhage, and DIC, among others. Whether shock occurs depends on the amount and speed of bleeding. When there is rapid and massive bleeding, exceeding 15% to 25% of the total blood volume, shock can result.

Dehydration

Common in severe vomiting, diarrhea, intestinal obstruction, profuse sweating, and polyuria in diabetes, among others. Shock caused by a sharp decrease in effective circulating blood volume due to dehydration was previously referred to as syncope.

Burns

Extensive burns leading to burn shock are due to the massive loss of plasma and reduced effective circulating blood volume, resulting in inadequate tissue perfusion. In the early stages, it is related to pain and hypovolemia, while in the later stages, it often progresses to septic shock due to secondary infections.

Infection

Severe infections caused by pathogenic microorganisms such as bacteria, viruses, fungi, and rickettsiae can lead to septic shock.

Septic shock is a special subtype of sepsis, characterized by severe circulatory disturbances and cellular functional metabolic abnormalities. It is characterized by the need for vasoconstrictor drugs to maintain mean arterial pressure above 65mmHg, even under adequate fluid resuscitation, and serum lactate levels higher than 2mmol/L (18mg/dl).

Trauma

Severe trauma can lead to severe pain, massive bleeding and fluid loss, tissue necrosis, resulting in traumatic shock.

Cardiac dysfunction

Extensive acute myocardial infarction, acute myocarditis, rupture of ventricular wall aneurysm, severe arrhythmias, and other cardiac conditions, as well as extracardiac obstructive lesions such as cardiac tamponade, pulmonary embolism, and tension pneumothorax, can lead to a sharp decrease in cardiac output and severe reduction in effective circulating blood volume, leading to shock. The former is called cardiogenic shock, and the latter is called obstructive shock.

Allergy

Individuals with certain allergic tendencies may experience anaphylactic shock following the injection of certain drugs (such as penicillin), serum preparations or vaccines, or even after ingesting certain foods or coming into contact with certain substances (such as pollen).

Intense neural stimulation

Severe pain, spinal cord injury or high-level spinal anesthesia, and excessive central sedative drugs can inhibit sympathetic vasoconstriction, leading to dilatation of resistance vessels, increased vascular bed volume, and relative insufficiency of effective circulating blood volume, resulting in neurogenic shock.

This type of shock has normal microcirculatory perfusion and a relatively good prognosis, and generally does not require treatment as it can resolve on its own.

Microcirculatory ischemic phase

Also known as the early stage of shock, the compensatory phase of shock, and the ischemic hypoxic phase.

Patients mainly present with pale complexion, cold and clammy extremities, rapid pulse, decreased pulse pressure, reduced urine output, and restlessness. Generally, the consciousness is clear, blood pressure may drop suddenly (as in the case of major bleeding), or it may drop slightly, or even due to compensatory effects, it may be normal or slightly elevated, but with a significant decrease in pulse pressure. Therefore, blood pressure alone cannot be used as an indicator of early shock.

Microcirculatory stasis phase

Also known as the reversible decompensated phase of shock, the progressive phase of shock, and the microcirculatory stasis hypoxic phase.

Patients mainly present with:

Progressive decrease in blood pressure and pulse pressure, often significantly decreased blood pressure, rapid and weak pulse, collapsed veins;

Central nervous system dysfunction, drowsiness, and even coma;

Severe renal hypoperfusion, oliguria or anuria;

Microcirculatory stasis, leading to increased levels of deoxygenated hemoglobin, resulting in cyanosis of the skin and mucous membranes or the appearance of petechiae.

Microcirculatory failure phase

Also known as the refractory phase, DIC phase, and irreversible phase. Patients in the microcirculatory failure phase mainly exhibit the following:

Circulatory failure

Persistent hypotension, or even unmeasurable, difficult to restore with vasopressors;

Low and weak heart sounds, rapid and weak pulse, or even unpalpable;

Decreased central venous pressure;

Collapsed superficial veins, making intravenous fluid difficult.

Complications of DIC

DIC is often complicated by disseminated intravascular coagulation, leading to anemia, subcutaneous ecchymosis, and petechiae.

Failure of important organ function

Aggravation of dysfunction in important organs such as the heart, brain, lungs, liver, and kidneys, can lead to symptoms such as dyspnea, oliguria, or anuria;

Manifestations of multi-organ dysfunction or multi-organ failure, such as confusion or even coma.

If conditions allow, patients should be encouraged to eat orally as much as possible to minimize fasting time, thereby promoting gastrointestinal motility to maintain intestinal mucosal barrier function.

The prevention of shock mainly involves avoiding various precipitating factors that may exacerbate the primary disease, such as avoiding contact with allergens and actively treating the underlying disease, including:

Patients who have experienced bleeding or fluid loss should promptly recognize signs of bleeding or fluid loss and seek medical attention;

Patients with burns or trauma should avoid wound infections;

Patients with infections require active treatment of the primary infection;

Patients with a history of allergies should avoid contact with allergens;

Patients with heart disease should monitor their blood pressure, adhere to treatment, and avoid cardiogenic shock;

Avoid stimuli such as pain;

Prompt medical attention in case of changes in vomit or stool color.