CRNAs are considered mid-level providers and, for at least services occurring in Nebraska, most carriers are individually credentialing all CRNAs. Some states have "opt out" laws that allow for a CRNA to personally perform anesthesia services, others do not and require they be supervised. As far as for how to bill for them, it depends on in what capacity they are performing services. Are they personally performing (QZ modifier) or being supervised (QX modifier)?