Types of Shock in Medicine

Shock

• Shock is a life-threatening condition of cardiovascular collapse, characterized by reduced circulating blood volume (hypotension) and inadequate perfusion of cells and tissues (hypoperfusion).
• Uncompensated shock can lead to impaired cellular metabolism and death.
• "True" or "secondary" shock is a circulatory imbalance between oxygen supply and demand at the cellular level.
• Clinically, primary shock presents with brief unconsciousness, weakness, sinking sensation, pale and clammy limbs, rapid pulse, and low blood pressure, lasting a few seconds or minutes.

Types of Shock

• Hypovolemic shock: This type of shock results from inadequate circulatory blood volume due to factors such as hemorrhage or loss of plasma volume.
• Major effects include increased heart rate (tachycardia), low blood pressure (hypotension), reduced urine output (oliguria to anuria), and altered mental state (ranging from agitation to confusion to lethargy).
• Cardiogenic shock: Acute circulatory failure resulting from a sudden drop in cardiac output due to heart disease without a reduction in blood volume. A common cause is severe left ventricular dysfunction, often from acute myocardial infarction.
• Septic (Toxemic) shock: Severe bacterial infections (or septicemia) induce septic shock. Gram-negative bacteria are a common cause (endotoxic shock); less often, Gram-positive bacteria (exotoxic shock) might cause septic shock. It originates in the genitourinary tract, alimentary tract, respiratory tract, or skin.

Stages of Shock

• Shock progresses through three stages:
  • Initial (compensated) stage: Reversible
  • Progressive stage: Decompensated
  • Irreversible stage: Decompensated

Morphologic Changes in Shock

• Shock induces changes in various organs such as:
  • The brain (hypoxic encephalopathy)
  • The heart (hemorrhage and necrosis)
  • The lungs (acute respiratory distress syndrome (ARDS))
  • The kidneys (tubular necrosis)
  • Adrenals (hemorrhage and necrosis)
  • The liver (focal necrosis)
  • The gut (hemorrhagic gastroenteropathy)

Clinical Presentation of Shock

• Low blood pressure
• Low body temperature
• Weak pulse
• Shallow breathing
• Pale and cold clammy skin

Thrombosis

• Thrombosis is the formation of a solid mass (thrombus) within the circulatory system from components of flowing blood.
• Hematoma is the extravascular accumulation of blood into tissues.
• A critical point in thrombosis is the formation of hemostatic plugs at the site of bleeding.
• Thrombosis can be life-threatening due to ischemic injury (reduced blood flow to tissues/organs) and potentially thromboembolism (a dislodged thrombus traveling to distant sites, causing blockages).

Fate of Thrombi

• Resolution: The thrombus can dissolve completely via the fibrinolytic system.
• Organization: If unresolved, it can organize.
• Propagation: Thrombi can grow through deposition from circulating blood components.
• Thromboembolism: Thrombi may detach and travel as emboli, causing problems at their new location. The detached thrombi can be quite fragile