relationships in my opinion are give and take, support, sharing, loving.... you're in the hospital unexpectedly, of course it is ok to want your guy there.
but i think it is important not to assume. perhaps your guys thought phone calls were enuff support? has this happened before?
in my humble opinion, its important to communicate and in this case be blunt... say "i need you to be here for me, even if it is just for a short time..." buthe in turn needs to communicate with his SO.
and not just what u need but what do the 3 of you need.
i was a secondary in my last poly relationship and on 3 distinct occasions in 3 yrs i had my guy there for me asap because i communicated to him "i need you here" and his SO was ok with it because we all communicated ahead and during said crisis....
"...Love itself is what is left over when being in love has burned away, and this is both an art and a fortunate accident." ~St Augustine