Final answer:
When a CRNA personally performs an anesthesia case without medical direction, the correct modifier to report their services is 'QZ'. This modifier signifies independent service by a CRNA.
Step-by-step explanation:
If a Certified Registered Nurse Anesthetist (CRNA) is personally performing an anesthesia case without medical direction from an anesthesiologist, the appropriate modifier to report the CRNA's services is modifier QZ. This modifier is used to indicate that the CRNA provided anesthesia services independently without an anesthesiologist's direction or supervision. It is important for billing and reimbursement purposes that the CRNA use the correct modifier to reflect the nature of the service provided.