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Mixed Venous Oxygen Saturation (SvO2)

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  Mixed Venous Oxygen Saturation (SvO2) SvO2 measures the oxygen saturation of blood in the pulmonary artery, providing an average of oxygen levels in blood returning to the heart from the entire body. It is a critical marker of tissue-level oxygen utilization. •  Low SvO2:  Indicates inadequate oxygen delivery to tissues, often due to decreased cardiac output, anemia, hypoxemia, or increased tissue oxygen demand. •  High SvO2:  May result from reduced tissue oxygen extraction (e.g., in sepsis or hyperthyroidism) or increased cardiac output. Key Points: 1 .  Measurement: SvO2 is measured by sampling blood via a pulmonary artery catheter, which collects mixed venous blood from the entire body. 2 .  Clinical Significance: It is used to evaluate tissue oxygenation, particularly in critically ill patients, and is essential for managing conditions such as shock or sepsis where oxygen delivery may be impaired. 3 .  Interpretation: Normal...
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Pulmonary Capillary Wedge Pressure (PCWP)

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  Pulmonary Capillary Wedge Pressure What does it measure? Pulmonary capillary wedge pressure (PCWP) is used to estimate left atrial pressure (LAP) indirectly. While left ventricular pressure can be measured by positioning a catheter directly in the left ventricle, it is impractical to navigate the catheter backward into the left atrium. Although LAP could technically be measured by inserting a specialized catheter into the right atrium and crossing the interatrial septum, this approach is rarely done due to the risk of damaging the septum and causing harm to the patient. Pulmonary Capillary Wedge Pressure (PCWP) Measurement PCWP is obtained using a balloon-tipped, multi-lumen catheter, known as a Swan-Ganz catheter, which is inserted into a peripheral vein (e.g., jugular or femoral vein). The catheter is guided through the right atrium, right ventricle, pulmonary artery, and into a smaller branch of the pulmonary artery. A lumen (port) at the catheter’s tip, located just beyond th...
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Hypotension, ICU, PCWP, MVO2

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  A 53-year-old woman is admitted to the ICU with hypotension. She is not receiving vasoactive medications and is breathing ambient air. Her intra-arterial blood pressure is 72/46 mm Hg, with a pulse rate of 120/min, regular. Invasive hemodynamic monitoring reveals:   Pulmonary capillary wedge pressure:  6 mm Hg  (normal range: 6-12 mm Hg)   Mixed venous oxygen saturation:  78%  (normal range: 65%-75%). What is the most likely cause of her condition? A. Cardiogenic shock B. Pericardial tamponade C. Right ventricular infarction D. Septic shock E. Volume depletion This patient’s presentation of low pulmonary capillary wedge pressure (PCWP) and high mixed venous oxygen saturation (MVO₂) is most consistent with septic shock.  Septic shock , a form of distributive shock, occurs due to a systemic infection that leads to significant peripheral vasodilation and reduced systemic vascular resistance (SVR). The decreased venous return lowers pulmon...
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