You cannot spike and/or flush IV lines if you are not a licensed nurse. Doing this requires that you are a licensed person and in doing so, you may be charged for practicing without a license. However, if you are qualified, you can perform the process but not as a daily routine.
You can assemble and spike them "IF" properly trained (anesthesia technologists do this). Under some circumstances, IV meds can be given by non-RNs (MRI technologists can give IV contrast in a peripheral IV-- (not a central line).