Shock (synonyms: Acute circulatory failure; Acute peripheral circulatory failure; Aseptic shock; Hemorrhage shock; Endotoxin shock; Hypovolemic shock; Hematologic shock; Hemorrhagic shock; Cardiac shock; Cardiogenic shock; Cardiorespiratory collapse; Cardiovascular collapse; Cardiovascular shock; Circulatory collapse; Circulatory failure; Peripheral vascular collapse; Peripheral circulatory failure; Shock due to hemorrhage; Vasomotor seizure; Volume deficiency shock; ICD-10 R57: Shock, not elsewhere classified) refers to circulatory failure due to inadequate perfusion (hypoxia/lack of oxygen supply) to organs.
There is a mismatch between the required and actual blood supply to the organism. This can be caused, for example, by a massive loss of blood in a traffic accident. The body then tries to concentrate on supplying blood to the most important organs, which, if prolonged, can have harmful effects on the other organs.
Hemodynamically (“fluid mechanics of blood”), shock is defined as sustained systolic blood pressure < 80 mmHg or arterial mean < 60 mmHg.
Shock is classified into four categories:
- Hypovolemic shock (= inadequate perfusion of organs due to mostly acute intravascular volume loss/acute volume deficiency); this is divided into four subgroups
- Hemorrhagic shock – due to acute bleeding without significant tissue damage.
- Traumatic-hemorrhagic shock – as a result of acute bleeding with tissue damage (→ release of activators of the immune system).
- Hypovolemic shock in the narrower sense: critical decrease in circulating plasma volume without acute hemorrhage
- Traumatic hypovolemic shock: critical decrease in circulating plasma volume without acute hemorrhage with tissue damage (→ release of mediators).
- Distributive shock – relative hypovolemia due to pathologic (pathological) redistribution of absolute intravascular volume (most common form of shock); this is divided into three subgroups:
- Anaphylactic shock (anaphylaxis) and anaphylactoid shock – shock resulting from a severe allergic reaction (usually as a mast cell-dependent allergic immediate reaction (type I, IgE-mediated; mainly due to insect venoms, food, and drugs) that results in a disturbance of peripheral circulatory regulation with relative volume deficiency due to increased capillary permeability, ie. i.e., shift from intravascular volume to extravascular (see below anaphylactic shock).
- Septic shock – shock due to severe generalized infection (blood poisoning), which results in a disturbance of peripheral circulatory regulation with relative volume deficiency due to vascular dilatation (vasodilatation) (see below sepsis)
- Neurogenic shock – shock due to irritation of the autonomic nervous system as a result of painful injury.
- Cardiogenic shock – shock due to acute pump failure (acute right heart failure (RHV), acute left heart failure (LHV): e.g., myocardial infarction (heart attack) (infarct-related cardiogenic shock (ICS)) (see below cardiogenic shock).
- Obstructive shock – flow obstruction in front of or behind the heart, i.e., condition caused by obstruction (constriction) of large vessels or the heart; similar in symptomatology to cardiogenic shock, but must be distinguished from it because of the fundamentally different therapeutic measures required
Shock can be a symptom of many diseases (see under “Differential diagnoses”).
Course and prognosis: Shock represents a life-threatening condition. The course and prognosis depend on the present form of shock. If left untreated, shock is usually fatal.The prognosis is largely dependent on early recognition and adequate treatment of shock.
