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Questions and Answers
What condition is characterized by a state of cellular and tissue hypoxia due to various factors?
What condition is characterized by a state of cellular and tissue hypoxia due to various factors?
Which of the following factors directly affects global oxygen delivery (DO2)?
Which of the following factors directly affects global oxygen delivery (DO2)?
Which scenario could potentially indicate high SVO2 levels?
Which scenario could potentially indicate high SVO2 levels?
What phase of shock is characterized by poor perfusion, low blood flow, and metabolic waste accumulation?
What phase of shock is characterized by poor perfusion, low blood flow, and metabolic waste accumulation?
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What is the normal range for Central Venous Oxygen Saturation (SVO2)?
What is the normal range for Central Venous Oxygen Saturation (SVO2)?
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Which factor is NOT a contributor to low SVO2 levels?
Which factor is NOT a contributor to low SVO2 levels?
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Oxygen extraction in tissues refers to the process of:
Oxygen extraction in tissues refers to the process of:
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What would a value greater than 75% for Central Venous Oxygen Saturation indicate?
What would a value greater than 75% for Central Venous Oxygen Saturation indicate?
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Study Notes
Shock Definition and Mechanisms
- Shock is a state of cellular and tissue hypoxia, caused by reduced oxygen delivery, increased oxygen consumption, inadequate oxygen utilization, or a combination.
Oxygen Delivery (DO2)
- Global oxygen delivery (DO2) is the total oxygen delivered to tissues per minute.
- Factors affecting DO2:
- Hemoglobin
- Cardiac Output (CO)
- Arterial oxygen saturation
Oxygen Consumption (VO2)
- Oxygen consumption (VO2) is the total oxygen removed from blood due to aerobic metabolism.
- Factors affecting VO2:
- Fever
- Inflammation
- Hyperthyroidism
- Adrenergic drugs
- Increased muscular activity
- Seizures
- Pain
- Vent weaning
Oxygen Extraction and SVO2
- Oxygen extraction is the amount of oxygen unloaded from hemoglobin to replenish tissues with low oxygen concentration.
- Low SVO2 indicates insufficient oxygen supply to meet tissue demands (increased oxygen consumption).
- High SVO2 indicates inadequate oxygen extraction from tissues.
- SVO2 = Ratio of O2 consumption (VO2)/ (DO2)
Contributors to Low and High SVO2
-
Low SVO2:
- Low hemoglobin
- Low cardiac output
- Heart failure
- Pulmonary emboli
- Increased oxygen demand
-
High SVO2:
- Sepsis
- Acidosis
- Hypothermia
- Excessive vasoactive drugs
Central Venous Oxygen Saturation (ScvO2)
- ScvO2 measures blood returning from the upper body (head and upper extremities) from the jugular or subclavian vein.
- It's minimally invasive.
- Normal range is 65%-75%.
- Values below 65% show concern.
- Values above 75% may indicate issues.
Shock Phases
- Initial: Decreased cardiac output, perfusion, and oxygenation; leading to anaerobic metabolism and lactic acidosis.
- Compensatory: Neuroendocrine mechanisms enhance cardiac output, blood flow, and volume restoration.
- Progressive: Compensatory mechanisms fail, resulting in poor perfusion, low blood flow, metabolic waste, and potential multi-organ dysfunction syndrome (MODS).
- Refractory: Cellular destruction; unresponsive to vasopressors; hypoxemic despite oxygen therapy; severe circulatory failure; impending death.
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Description
This quiz covers the definitions and mechanisms of shock, focusing on cellular and tissue hypoxia due to varying oxygen delivery and consumption factors. You'll explore concepts such as global oxygen delivery (DO2), oxygen consumption (VO2), and their relevance in clinical settings.
