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Pathophysiology · Chapter 20. Extreme and Terminal States

Vascular collapse

Collapsus

Collapse is an acute circulatory failure caused by a sharp mismatch between the circulating blood volume and the vascular capacity. This leads to a critical drop in blood pressure and tissue oxygen deprivation (primarily affecting the brain), while consciousness is usually preserved in the patient.

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Key featureCritical drop in blood pressure.
Cerebral blood flowPrimary circulatory hypoxia with preserved consciousness.
Core pathogenesisMismatch between circulating blood volume and vascular bed capacity.
Forms of acute vascular failureSyncope, collapse, shock.
2 min readFor medical studentsUpdated 10.10.2026
Material prepared by WhiteCoat Pro editorial team based on platform study guidesPending instructor review

Pathogenetic mechanisms (classification)

Based on the leading pathogenetic mechanism, collapse is divided into three main types:

  1. Cardiogenic. It develops due to a sharp drop in cardiac output. This occurs in acute heart failure (valvular defects, pronounced arrhythmias) or obstacles to blood flow to the heart (embolism, stenosis).
  2. Hypovolemic. Associated with rapid loss of circulating blood volume. Causes include massive blood loss, plasma loss (extensive burns), or severe dehydration (intractable vomiting, profuse diarrhea, heavy sweating). This also includes blood redistribution, where blood pools in the venous bed and capillaries.
  3. Vasodilatory (vascular). Occurs with a sharp decrease in the tone of arterioles and venules. It may be caused by endocrine pathology (adrenal insufficiency, hypothyroidism), medication overdose (sympatholytics, ganglionic blockers), or accumulation of biologically active substances (histamine, kinins).

The place of collapse among other forms of acute vascular failure

In the pathophysiology course, collapse is considered alongside other manifestations of acute vascular failure. It is important to differentiate them:

  • Syncope (fainting) — brief loss of consciousness due to transient cerebral ischemia.
  • Collapse — vascular failure due to rapid pooling of blood in organs; in typical cases, it is not accompanied by loss of consciousness (which may only be clouded).
  • Shock — a severe condition with generalized perfusion disorders and multiorgan failure.
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Special case: collapse in hypothyroid coma

Collapse can act as a formidable complication in hypothyroidism. Coma is triggered by hypothermia, infections, bleeding, stress, or the intake of certain medications (anesthetics, barbiturates).

The pathogenesis of vascular disorders is based on:

  • Pronounced bradycardia due to thyroid hormone deficiency and reduced sensitivity to catecholamines.
  • Severe hypotension caused by a drop in circulating blood volume, cardiac output, and total peripheral vascular resistance.

These factors, combined with respiratory failure, lead to progressive hypoxia, acidosis, depression of consciousness, and hypothermia.

Class and exam questions

What is the main difference between collapse and syncope?

Syncope involves a rapid and brief loss of consciousness. In collapse, consciousness is preserved, although it may be clouded.

What is primary circulatory hypoxia?

This is a shortage of oxygen in tissues that occurs primarily due to insufficient blood flow (decreased pressure and impaired perfusion), rather than problems with the lungs or blood.

Why does respiratory failure develop in hypothyroid coma?

It is caused by alveolar hypoventilation: the excitability of the respiratory center decreases, the respiratory tract and air-blood barrier swell, and pulmonary blood flow drops.

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What else to study on this topic

  • Pathogenesis of multiorgan disorders in shock
  • Compensation mechanisms in acute blood loss
  • The role of kinins and histamine in vascular tone
  • Etiology of infectious and toxic collapse
  • Acidosis: mechanisms of development in hypoxia

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Other topics in "Chapter 20. Extreme and Terminal States"

Terminal StatesExtreme StatesStages of Extreme StatesTherapy of Extreme StatesCollapseShockCompensated shock stageDecompensated shock stageTraumatic and burn shockConsciousness disordersComaPathogenesis of comaTherapy of comatose statesSudden infant death syndromeEffects of electric current on the body
The entire section "Chapter 20. Extreme and Terminal States"

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