 Chest drains are an essential part of the treatment for patients with fluid or air around the lung, which usually causes breathlessness. Draining the fluid or air relieves symptoms and allows investigations to be carried out that can identify a cause for why the fluid or air is there. Chest drains are difficult to secure in place, and sometimes fall out despite the best possible care. This study tests a modified drain that has a small balloon near the end which, when inflated inside the chest cavity, should make it much harder for the drain to fall out of the chest. This was tested in a small pilot study, with encouraging results. The current study is comparing a group of patients treated with the new ballooned drain against a group treated with the standard drain, with patients equally but randomly allocated to each group. The chest drain has been through rigorous laboratory testing and has been CE marked for human use. 