I just had my 5th lung surgery and for the first time experienced a prolonged air leak which lasted 2 weeks.
Following are some information I found on the subject and would like to share in case anybody else goes through it...
An article about the complications of VATS (Video Assisted Thoracoscopic Surgery):
My chest tube was first attached to a pleur-evac device:
http://clinicalengineering.duhs.duke.edu/wysiwyg/downloads/pvac.pdf
The air leak was identified because of the presence of bubbles in the area labelled airleak meter in figure 1 of the document.
First I was put in suction mode (this is supposed to help the lung expand) but eventually the suction was removed although the bubbles were still there. After a week and a half, my surgeon decided I could go home with a heimlich valve:
http://en.wikipedia.org/wiki/Flutter_valve
http://www.upstate.edu/pated/document/heimlichvalve.pdf
With this valve, I could see the rubber sleeve inflate/deflate while the leak was still there. When the leak stopped though, the rubber sleeve stopped changing shape even when I was coughing...