strange question about chairs for vest users

My adult son uses an airway clearance vest 2 times a day. He is pancreatic sufficient and not on the skinny side. He needs to sit at a desk while he does the vest so he can do nebs (and look at a computer screen to ease boredom) at the same time. Anyway, with the oscillation of the vest, he has so far broken 4-5 different chairs. Some break while he is on the chair, and some break several days or months later. Several of them were Danish modern quality chairs made of teak from a high end furniture store. Several of them were less expensive chairs with caning. It seems that any chair with joints that can come apart from constant shaking will eventually fail. We don't want to put him on a slouchy sofa while he does the vest as that is not great for clearance, but that is the only thing I can think of that won't fall apart. So, what kind of chair do you folks use that does not break from the constant resonance?
Source: Cystic Fibrosis Adults Forum - Category: Respiratory Medicine Authors: Tags: Adults Source Type: forums