Cardiac tamponade may occur following cardiac surgery as a result of blood or fluid collecting in the pericardial space compressing the heart and reducing cardiac output. Mediastinal chest drains (including pericardial drains) are inserted as standard postoperative practice following cardiac surgery to assist the clearance of blood from the pericardial space. To prevent chest tubes from blocking and causing tamponade nurses manipulate them to prevent clots. Manipulation methods including milking, stripping, fanfolding and tapping may be applied to the tubes. Evidence is needed regarding the safest and most effective means of preventing chest tube blockage and cardiac tamponade.