Final answer:
The correct position for a patient with a suspected air embolism after disconnecting TPN tubing is on the left side with the head lower than the feet to prevent the air from reaching crucial areas such as the lungs and heart.
Step-by-step explanation:
When a patient with Total Parenteral Nutrition (TPN) infusing has disconnected the tubing from the central line catheter and an air embolism is suspected, the nurse should immediately place the patient in the position known as the "left lateral decubitus" position, which is option A: On the left side, with the head lower than the feet. This position helps prevent the air bubble from moving to the lungs and heart by trapping it in the right side of the heart, which is anatomically lower when the patient is on their left side.