Since the respiratory airways branch to all parts of the lungs and ready access is provided through the nose or mouth, exploration of these passages for direct visualization or tissue sampling has long been a clinical challenge. This would be particularly helpful in diagnosing those pulmonary diseases that involve the bronchial tree or affect the surrounding lung parenchyma which prove difficult to diagnose or define by indirect methods. The pioneering efforts of Chevalier Jackson in 1918, using bismuth insufflation for radiologic visualization of the bronchial tree, and of Sicard and...