European Respiratory Monograph 31 April 2005 Editor in Chief E.F.M. Wouters This book is one in a series of European Respiratory Monographs. Each individual issue provides a comprehensive overview of one specific clinical area of respiratory health, communicating infor- mation about the most advanced techniques and systems needed to investigate it. It provides factual and useful scientific detail, drawing on specific case studies and looking into the diagnosis and management of individual patients. Previously published titles in this series are listed at the back of this book with details of how they can be purchased. Mon 31 page ii.qxd 13/04/2005 11:45 Page 1