Payment at Medically Supervised Rate
Only three (3) base units per procedure are allowed when the anesthesiologist is involved in
rendering more than four (4) procedures concurrently or is performing other services while
directing the concurrent procedures. An additional time unit can be recognized if the physician
can document he/she was present at induction. Modifier AD is appropriate when services are
medically supervised.
Payment Rules
The fee schedule allowance for anesthesia services is based on a calculation that includes the
anesthesia base units assigned to each anesthesia code, the anesthesia time involved, and
appropriate area conversion factor. The following formulas are used to determine payment:
• Participating Physician not Medically Directing (Modifier AA)
(Base Units + Time Units) x Participating Conversion Factor = Allowance
• Non-Participating Physician not Medically Directing (Modifier AA)
(Base Units + Time Units) x Non-Participating Conversion Factor=Allowance
• Participating Physician Medically Directing (Modifier QY, QK)
(Base Units + Time Units) x Participating Conversion Factor = Allowance x 50%
• Non-Participating Physician Medically Directing (Modifier QY, QK)
(Base Units + Time Units) x Non-Participating Conversion Factor = Allowance x 50%
• Non-Medically Directed CRNA (Modifier QZ)
(Base Units + Time Units) x Participating Conversion Factor = Allowance
• CRNA Medically Directed (Modifier QX)
(Base Units + Time Units) x Participating Conversion Factor = Allowance x 50%
