A patient on volume-controlled ventilation has a blood gas indicating adequate ventilation but is hypoxic. If PEEP is increased and cardiac index drops significantly, what should the therapist do next?

In the context of a patient experiencing hypoxia while on volume-controlled ventilation, it is crucial to balance the use of PEEP with the patient’s hemodynamics. When increasing PEEP results in a significant drop in cardiac index, it indicates that the elevated intrathoracic pressure may be impairing cardiac output by reducing venous return. In this scenario, if the PEEP level is causing hemodynamic instability, the most appropriate step is to lower the PEEP.

Decreasing PEEP alleviates the pressure on the heart and large vessels, potentially restoring blood flow and improving cardiac output while still allowing for adequate ventilation. The goal is to optimize oxygenation without compromising hemodynamics.

Other options like performing an optimal PEEP study might assess the effectiveness of PEEP but won't immediately address the acute drop in cardiac index. Increasing the FIO2 to either 1.0 or 0.70 could temporarily improve oxygen saturation; however, these measures don't address the underlying hemodynamic issue caused by high PEEP. Therefore, reducing PEEP is the most immediate and effective intervention to restore hemodynamic stability while addressing the hypoxia.