Resources for updating resume?

[kccRN, BSN, RN]

I’ve been working as an ICU nurse for 8+ years. I’ve been in the same position since graduating nursing school and have advanced up the clinical ladder on my unit but I have not touched or updated my resume since starting here over 8 years ago. I want to update my resume but I don’t know what to keep on there and what to get rid of at this point. Do I keep volunteer work done in college or work experience prior to college? What kind of detail/skills do I add about my current job? Do I just delete everything prior to college or keep anything that may be relevant experience? Thanks!