In 1919, Mrs. Ray Werner patented a military overcoat with an inflatable lining:

The primary object of my invention is to provide a garment, the back of which may be inflated to provide a resilient support for the body of the wearer without removing the garment, thus providing a greater comfort while reclining in a recumbent position.

A separate compartment can be inflated into a pillow. The application was granted that September; I don’t know whether it was ever manufactured.