What can be a consequence of elevated levels of PEEP during mechanical ventilation?

Elevated levels of Positive End-Expiratory Pressure (PEEP) during mechanical ventilation can significantly decrease venous return to the heart. PEEP prevents the complete expiration of air from the lungs, which helps keep the alveoli open and recruit collapsed lung units, improving oxygenation. However, when PEEP levels are high, the positive pressure in the chest can compress the great vessels (like the vena cava), thereby reducing the return of blood to the heart.

This reduction in venous return can lead to decreased cardiac output, as the heart receives less blood to pump with each heartbeat. It's essential to monitor hemodynamics closely when using high levels of PEEP to ensure adequate circulation and cardiac function are maintained.

In contrast to the other options, which do not generally result from elevated levels of PEEP in the described manner, a decrease in venous return is a recognized and critical concern in mechanical ventilation management, making it the correct answer.