1) Thoracometer 
instrument measuring chest expansion during breathing
• (n.) An apparatus for measuring the external movements of a given point of the chest wall, during respiration; -- also called thoracometer.
Ste·thom'e·ter noun [ Greek ... chest + -meter .] (Physiol.) An apparatus for measuring the external movements of a given point of the chest wall, during respiration; -- also called thoracometer . 
an instrument for measuring the expansion of the chest and abdomen during respiration.