Final answer:
A suction unit used with a chest tube should be positioned below the patient to assist in proper drainage and maintain negative pressure necessary for lung re-expansion.
Step-by-step explanation:
The suction unit used on a patient with a chest tube should always remain below the patient. This is to ensure that gravity can assist in the drainage process and maintain the necessary negative pressure within the chest cavity to allow the lungs to re-expand properly after surgery or trauma
A chest tube functions by removing air, fluids, or pus from the intrathoracic space, which helps to reestablish the negative pressure needed for lung expansion. Setting up the suction unit correctly is crucial; placement above or level with the patient could entail risks such as backflow or insufficient drainage.