A patient presents with hypotension after being placed on high PEEP. What is this a sign of?

Hypotension following the application of high Positive End-Expiratory Pressure (PEEP) can indicate decreased cardiac output. High PEEP levels can reduce preload by decreasing venous return to the heart, as the increased intrathoracic pressure can compress the great vessels and limit the amount of blood filling the heart during diastole. This reduction in blood volume returning to the heart can lead to lower stroke volume and, consequently, a decrease in cardiac output, which directly impacts blood pressure, leading to hypotension.

Additionally, it is important to consider that while high PEEP can influence afterload by causing increased intrathoracic pressure, the most immediate and significant impact in this scenario is typically a decrease in cardiac output and preload due to venous compression. Therefore, understanding the hemodynamic effects of PEEP is critical in managing patients, particularly those with compromised cardiovascular status, where maintaining optimal blood pressure is essential.