Reading the details:
OK, brief pharmacology info
midazolam is a benzo, same as valium or xanax
hydromorphone is obviously and opiate
So, basically, the same death as someone who shoots up Valium and heroin and ODs.
You are given essentially the same mixture when you get procedures like colonoscopy - obviously lower doses
You get midazolam (Verced) and instead of hydromoprhone you usually get Fentanyl.
He was gasping for air because benzo+opiate suppresses respiratory drive, by the time this happens, you would have passed out long ago. So, while it may have looked freaky to onlookers, I can guarantee you 99.999999% that he died completely and utterly pain free.
This is just uneducated public + lawyers trying to score some cash.