YA Fantasy series. Someone is in a coma, kept alive by machines. Friend/ relative travels to the ghost world to find this person's spirit and help return it to their body. Read in 1990s.

[Edward]

Read in the 90s. I believe is part of a series.

A person is in a coma kept alive by machines. Doctors plan to switch off the machines as they believe the person's spirit is gone.

A friend/relative has the ability to travel to the ghost plane/world (possibly in their sleep?) and searches for the person's spirit to help return to their body before the machines are switched off.

In the ghost world there was an encounter with a dinosaur as well as with Elvis.

[Kris]

Just to confirm, is this book for teens (= YA, in this group) or adults?