The Collaborative International Dictionary of English v.0.48:

Gastropneumatic \Gas`tro*pneu*mat"ic\, a. [Gastro- + pneumatic.]
   (Anat.)
   Pertaining to the alimentary canal and air passages, and to
   the cavities connected with them; as, the gastropneumatic
   mucuos membranes.
   [1913 Webster]