And no... You have an air leak. (Give myself the Captain Obvious award for that statement alone). Causes for such are many, compounded with the fact your patient has an open chest (retracted open, or just not sutured?). Is this leak related to a communication through the dressing placed in the OR, secondary to lung injury (trauma, surgical, cancer, COPD bleb......)
Chest tubes placed into the mediastinum are done to drain blood postoperatively and to prevent cardiac tamponade.
Any time you have an air leak that was not noted in the OR at time of placement, you essentially start from the patient and work back. Make sure your dressings are secure, tube connections valid, no possibility of this communication of air is occuring outside the patient.
To be honest, it doesn't suprise me that a patient with an open chest has an air leak from the adjacent mediastinum being open. Everything that keeps their chest enclosed has been interrupted (either surgically and / or due to and now "patched" closed. It may not be "air tight". You may have a communication from the pleural cavity, I don't know given the level of information given with this post.
A good link to review / research: Go with the flow of chest tube therapy
I apologize that this reply is not as linear as I'd like it to be, please post / PM if more information requested.