American Board of Surgery Qualifying Exam (ABS QE) Practice Test

In cardiogenic shock, the heart's ability to pump blood effectively is compromised, leading to several physiological changes. An important consequence of the heart's impaired function is the increase in pulmonary capillary wedge pressure (PCWP). This is due to the backup of blood flow higher up in the circulation because, when the heart fails to pump sufficiently, the pressure in the left atrium and subsequently in the pulmonary circulation rises.

As the left ventricle struggles to eject blood, this accumulation leads to increased hydrostatic pressure in the pulmonary capillaries, resulting in elevated PCWP. This is a key indicator of fluid overload and heart dysfunction in patients experiencing cardiogenic shock, often manifesting clinically as pulmonary edema.

While decreased central venous pressure (CVP) and decreased cardiac output (CO) are also observed in cardiogenic shock, increased PCWP is particularly significant as it reflects the state of congestion in the pulmonary vasculature. Increased systemic vascular resistance (SVR) can also occur as a compensatory mechanism to maintain blood pressure in the setting of low cardiac output, but the hallmark finding in the context of this condition is the elevated PCWP. Thus, recognizing the increased PCWP is essential for diagnosing and managing cardiogenic shock.