Question

Capillary Wedge pressure is decreased in what type of shock?

• A. Cardiogenic
• B. Early Septic
• C. Late Septic
• D. Obstructive

Hint:

Summary of Shock Hemodynamics:
$\bullet$ Hypovolemic: PCWP $\downarrow$, CO $\downarrow$, SVR $\uparrow$
$\bullet$ Cardiogenic: PCWP $\uparrow$, CO $\downarrow$, SVR $\uparrow$
$\bullet$ Early Septic (Distributive): PCWP $\downarrow$ (or normal), CO $\uparrow$, SVR $\downarrow$
$\bullet$ Obstructive: PCWP $\uparrow$ (or equalized), CO $\downarrow$, SVR $\uparrow$

Answer 1

The Correct Option is B

Concept:
Pulmonary Capillary Wedge Pressure (PCWP) provides an accurate indirect estimate of left ventricular end-diastolic pressure (LVEDP) and left atrial filling pressure (preload).
Hemodynamic profiling using PCWP, Cardiac Output/Index, and Systemic Vascular Resistance (SVR) allows precise classification of the underlying type of circulatory shock.
Explanation:
• Distributive Shock (e.g., Early/Warm Septic Shock):
- Widespread arterial and venous vasodilation due to inflammatory mediators leads to pooling of blood in capacitance vessels and increased capillary permeability.
- This causes a substantial reduction in effective circulating volume and venous return, leading to a decreased PCWP ($<8\text{--}12\text{ mmHg}$) and decreased SVR, typically with a compensatory elevated cardiac output.

• Cardiogenic Shock:
- Primary pump failure causes blood to back up into the pulmonary circulation, leading to an elevated PCWP ($>15\text{--}18\text{ mmHg}$) and decreased cardiac output with elevated SVR.

• Obstructive Shock (e.g., Cardiac Tamponade, Tension Pneumothorax):
- Extrinsic compression impairs diastolic filling; intracardiac/wedge pressures are characteristically elevated or equalized.

• Late/Cold Septic Shock:
- Secondary myocardial depression and profound hypovolemia occur; if fluid resuscitation has taken place, PCWP may normalize or elevate due to myocardial dysfunction.
Final Answer:
Capillary wedge pressure is decreased in distributive shock states, such as Early Septic Shock, due to systemic vasodilation and reduced venous return.