Question

An ATU student suffered organ failure due to hypoxia. A cascade of circulatory disturbances led to hypoxia; embolism, thrombosis, endothelial cell injury, infarction, hypoxia.
Arrange these circulatory disturbances as 1 event leading to the other and explain how they happen.

Answer 1

Organ failure is organ dysfunction to such a degree that normal homeostasis cannot be maintained without external clinical intervention. It is not a diagnosis. It can be classified by the cause, but when the cause is not known, it can also be classified by whether the onset is chronic or acute

Hypoxia:- is a condition in which the body or a region of the body is deprived of adequate oxygen supply at the tissue level. Hypoxia may be classified as either generalized, affecting the whole body, or local, affecting a region of the body.

An embolism:- is the lodging of an embolus, a blockage-causing piece of material, inside a blood vessel. The embolus may be a blood clot (thrombus), a fat globule (fat embolism), a bubble of air or other gas (gas embolism), or foreign material.

Thrombosis:- is the formation of a blood clot, known as a thrombus, within a blood vessel. It prevents blood from flowing normally through the circulatory system.

When a blood clot forms in the veins, it is known as venous thromboembolism. This can cause deep vein thrombosis and pulmonary embolisms. When a clot forms in the arteries, it is called atherothrombosis, which can lead to heart attack and stroke

Injury to the vascular endothelium:- is a critical event in acute inflammatory disease processes. In acute inflammation, endothelial cell injury is frequently mediated by activated neutrophils. The process by which activated neutrophils produce endothelial cell damage .

Infarction :- obstruction of the blood supply to an organ or region of tissue, typically by a thrombus or embolus, causing local death of the tissue.

Pathophysiology of Hypoxia

• Endothelial dysfunction can be caused by several conditions, including diabetes or metabolic syndrome, hypertension, smoking, and physical inactivity . The healthy endothelium not only arbitrates endothelium-dependent vasodilation, but also actively suppresses thrombosis, vascular inflammation, and hypertrophy.
• chronic endothelial cell injury contributes to the development of anastomotic narrowing and the progression of atherosclerosis. Atheroscerosis :-Atherosclerosis refers to the buildup of fats, cholesterol and other substances in and on your artery walls (plaque), which can restrict blood flow. The plaque can burst, triggering a blood clot. Although atherosclerosis is often considered a heart problem, it can affect arteries anywhere in your body.
• A thrombus (A thrombus is a blood clot that forms in a vein) reduces the flow of blood through the vessel. An embolus is anything that moves through the blood vessels until it reaches a vessel that is too small to let it pass. When this happens, the blood flow is stopped by the embolus. An embolus is often a small piece of a blood clot that breaks off (thromboembolus).
• Arterial thromboembolism may lead to cerebral or other vital end-organ infarction.
• Venous thromboembolism is Pulmonary embolism, which has the following pathophysiologic effects:

1. Increased pulmonary vascular resistance secondary to vascular obstruction, neurohumoral mediators, cytokines, and reflex vasoconstriction.
2. Impaired gas exchange secondary to increased alveolar dead space, ventilation-perfusion mismatch, and right- to-left shunt
3. Compensatory alveolar hyperventilation
4. Right heart dysfunction and dilatation secondary to increased pulmonary artery pressure, wall tension, oxygen consumption, and ischemia
5. Bronchoconstriction and increased airway resistance
6. Reduced lung compliance secondary to edema, hemorrhage, and surfactant loss.

• A myocardial infarction (MI), also known as a heart attack, occurs when blood flow decreases or stops to a part of the heart, causing damage to the heart muscle. myocardial infarction (MI) usually results from an imbalance in oxygen supply and demand, which is most often caused by plaque rupture with thrombus formation in an epicardial coronary artery, resulting in an acute reduction of blood supply to a portion of the myocardium.
• Myocardial hypoxia is the result of disproportion between oxygen supply and demand. hypoxemia may result from pulmonary congestion, atelectasis, or ventilatory impairment secondary to complications of MI.
• Most tissues of the body respond to hypoxia through vasodilation. By widening the blood vessels, the tissue allows greater perfusion. By contrast, in the lungs, the response to hypoxia is vasoconstriction. This is known as hypoxic pulmonary vasoconstriction.
• In severe hypoxia, or hypoxia of very rapid onset, ataxia, confusion / disorientation / hallucinations / behavioral change, severe headaches / reduced level of consciousness, papilloedema, breathlessness, pallor, tachycardia, and pulmonary hypertension eventually leading to the late signs cyanosis, slow heart rate / cor pulmonale, and low blood pressure followed by heart failure eventually leading to shock and death.