What factor characterizes obstructive shock?

Obstructive shock is characterized primarily by impaired venous return to the heart due to a mechanical obstruction. A key feature of this condition is that it often leads to an increased pulmonary capillary wedge pressure. This increase occurs because the obstruction can elevate pressures in the vascular system, particularly in the pulmonary circulation, as it hinders normal blood flow.

As the heart struggles to pump blood effectively due to this obstruction, the pressure builds up in the pulmonary capillaries, reflecting back and causing an elevation in the pulmonary capillary wedge pressure. This is indicative of the heart's inability to adequately manage blood flow, resulting in stagnation and pressure changes upstream while downstream effects can occur depending on the specific nature of the obstruction.

In contrast, decreased systemic vascular resistance, decreased cardiac output, and increased mixed venous oxyhemoglobin saturation are not characteristic of obstructive shock. Often, during obstructive shock events, the systemic vascular resistance may remain normal or even increase as the body tries to compensate for reduced cardiac output due to the obstruction. Similarly, the cardiac output is typically reduced in obstructive shock due to the obstruction. The mixed venous oxyhemoglobin saturation is often decreased because of impaired oxygen delivery and utilization, contrasting with the option indicating an increase.