New to anesthesia coding and I have a question on billing the units or quantity. CPT is 01992 QZ, QS. Anesthesia time: Start 1412 End 1425 with total time being 13 minutes. Anesthesia is saying to bill 6 units. This procedure code has a base value of 5 units. How are they getting 6 units? Also, for CMS to pay for 01992 does there have to be a pre-operative evaluation, etc. Any help appreciated!