A DNR can be a legitimate judgment that the underlying condition cannot be treated, and that further aggressive attempts (e.g. rib-breaking chest compressions) will only be burdensome and futile.
It does not exclude the not-insignificant chance of an unexplained improvement in the patient' condition, either physical or emotional.. A lethal injection is a deliberate murder.It intentionally eliminates ALL chances.
All her chances have been eliminated. You don’t know what you would really do if you faced similar circumstances. Maybe she should wait a bit longer if she can still function, but the end result is not going to change.