Find someone who had a similar injury and is now 60-70. Ask them to tally up how much it cost them over their lifetime so far. Is is roughly what the adjuster is offering? If so, accept it. Otherwise counter with your own lifetime cost estimate. Attorneys (and adjusters!) have tables for these things, to base claims on. Ask yourself how much you'd want as a third party to assume liability (meaning you'd pay all bills incurred the rest of their natural life). Don't settle for less than that or they're just leaving you holding the bag for something you neither caused or are responsible for.

Also: find out if the injury will be considered a pre-existing condition. If so you may find it extremely expensive to buy health insurance on your own. This needs to be factored into the claim.