In eliciting physical signs, it is perhaps better to record simply what is seen, felt and heard with no thought of the conditions producing them. When it comes to the interpretation of the signs, however, the mechanism of their production is of fundamental importance.
Many years ago bronchoscopic studies demonstrated the mechanism of the physical signs of foreign bodies in the bronchi, and the correlated studies demonstrated that the understanding of this mechanism is essential for the proper interpretation of the physical signs.1 Moreover, it soon developed that a full comprehension of the mechanism of the signs greatly increased their diagnostic value as to the presence of a foreign body and especially as to its exact location. In hundreds of cases, bronchoscopicobservation of the foreign body has proved the accuracy of the localization of the intruder as indicated by the interpretation of the physical signs based on the bronchoscopically
JACKSON C. THE MECHANISM OF PHYSICAL SIGNS IN NEOPLASTIC AND OTHER DISEASES OF THE LUNGWITH ESPECIAL REFERENCE TO ATELECTASIS AND EMPHYSEMA. JAMA. 1930;95(9):639–644. doi:10.1001/jama.1930.02720090001001