For people who have had lung surgery, it is important to understand the impact of measuring air leaks accurately in both the short term and the long term. An electronic medical device called Thopaz measures air leak electronically. Another medical device called Pleur-evac measures air leak numerically. The purpose of this study is to understand the accuracy of the method used by doctors and nurses to determine if a chest tube has an air leak. It is also important to determine the size or severity of an air leak.