chronic post -op hiccoughs, anybody had this?

Howdy all,
So, my buddy had unexpected hip surgery after crashing his bicycle last week (that’ll teach him to try and pass me) and although he’s doing well it seems he has some chronic hiccoughs. He tells me they are pretty annoying at times and seem to be relieved by his percocet so I’m thinking that it’s related to being intubated and some irritation to the airway. His surgeon just kind of shrugged his shoulders so I’m wondering if anyone on the dope has had a similar experience and how long it took it to pass. Thanks in advance,