Are you referring to additional units for physical status modifiers and qualifying circumstances, or using a different unit value altogether (such as 1 unit - 10 minutes)?. Medicare recognizes 1 unit = 15 minutes, and most commercial payers do the same. Now, in anesthesia billing, there are opportunities to capture extra units based on the patient's health (physical status) or other special conditions (qualifying circumstances). Medicare does NOT recognize extra units for these codes/modifiers, but commercial payers sometimes do. If you don't already, I would recommend getting a current Relative Value Guide book. In it anesthesia billing is clarified, and it explains that a P3 physical status would be worth 1 extra unit, P4 = 2 extra units, and P5 = 3 extra units. Some of the qualifying circumstances codes carry an extra base unit value of 2 or 5 that can be added on. But remember: Medicare does not recognize or pay extra for these.
I hope this answers your question...