Were patients’ bodies or sheets moved around any to forestall bedsores? Or was that considered a possible complication that couldn’t be prevented?
Prevention of bedsores is a basic skill in nursing, and has been so for a long time. In fact, but somewhat unfairly, the development of a bedsore is often taken as a clear indication of inadequate, or even negligent nursing care*.
Although I can’t give you a cite, I can guarantee that patients in iron lungs were routinely re-positioned in attempt to prevent bedsores. That would have especially been the case for a patient in whom there was little else to offer in terms of physical therapy.
If you use the more modern (and less inflammatory) term “decubitus ulcer” or even “pressure ulcer”, you may come up with some hits on a web search. I actually searched the medical literature for iron lung + decubitus ulcer and came up with only a single hit. Still, it stated pretty clearly that pressure ulcers did occur in users of iron lungs.
*“bedsores” are not only due to inappropriate or inadequate positioning of the patient. Hence, the term preferred and used more often nowadays is “decubitus ulcer”. Often, there is an element of malnutrition contributing, as well as an ulcer-promoting effect on tissues as a result of absent nerve supply.
ETA: Much of the research considered in the second linked article comes from the work of John Olerud, father of the baseball player of the same name 