For a client suspected of having an air embolism, which action should the nurse take first?

The priority action for a client suspected of having an air embolism is to clamp the central line catheter. This is crucial because air embolisms occur when air enters the vascular system, potentially leading to severe complications such as cardiac arrest or stroke. By clamping the central line, the nurse prevents further air from entering the system, which is essential for stabilizing the patient's condition.

After ensuring that the central line is clamped to prevent additional air entry, other actions can be taken to support the client’s recovery, such as administering oxygen to help manage hypoxia, positioning the patient properly, or monitoring vital signs for any changes. However, immediate action focused on stopping the source of the embolism takes precedence to minimize the risk of further harm to the patient.