What are the potential complications of prolonged mechanical ventilation?

Prolonged mechanical ventilation can lead to ventilator-associated pneumonia (VAP), which is a serious complication that arises due to the presence of the endotracheal tube, which can serve as a conduit for bacteria to enter the lower respiratory tract. The inability to clear secretions effectively and the altered respiratory flora associated with mechanical ventilation further contribute to this risk. VAP is characterized by the development of a new lung infiltrate occurring 48 hours or more after intubation, accompanied by clinical signs of infection, such as fever and purulent sputum.

The other options highlight conditions that do not directly stem from mechanical ventilation. While hyperkalemia can occur due to various factors such as renal failure or metabolic disturbances, it is not a direct result of prolonged mechanical ventilation. Fluid overload may occur in critically ill patients but is not inherently caused by mechanical ventilation; rather, it can result from fluid management issues or underlying conditions. Thrombocytopenia may arise in the ICU due to multiple reasons such as sepsis or medication effects, but again, it is unrelated to the act of providing mechanical ventilation itself. Thus, ventilator-associated pneumonia is the complication most specifically associated with prolonged mechanical ventilation.