Paid by units, not by visits
Anesthesia is paid differently from almost every other service. Each case is valued as base units for the type of surgery plus time units for the minutes of anesthesia, multiplied by a payer-specific conversion factor. Who provided the care — an anesthesiologist alone, a CRNA alone, or a physician directing several CRNAs — changes the modifiers and the payment split. Accurate anesthesia time and the right modifiers are therefore worth as much as the code itself.
How a case is valued
| Element | Where it comes from |
|---|---|
| Anesthesia code (00100–01999) | Crosswalked from the surgical procedure performed, by body area and type of surgery |
| Base units | Assigned to each anesthesia code |
| Time units | Minutes from the start of anesthesia preparation with the patient to when the anesthesia provider is no longer in personal attendance, usually 15 minutes per unit |
| Physical status and qualifying circumstances | Modifiers P1–P6 and add-on codes 99100–99140; paid by some commercial payers, not by Medicare |
| Conversion factor | Set by the payer or contract, often varying by locality |
Start and stop times must be documented exactly, and gaps in continuous attendance are excluded. When several procedures are done in one session, only the anesthesia code with the highest base units is billed, with total time.
Who provided the care
- AA: anesthesiologist personally performed the case.
- QK: anesthesiologist medically directed two to four concurrent cases; the CRNA bills each case with QX.
- QY: anesthesiologist medically directed one CRNA.
- QZ: CRNA performed the case without medical direction.
- AD: supervision of more than four concurrent cases, paid at a reduced rate.
Medical direction requires the anesthesiologist to meet specific requirements for each case — including the pre-anesthetic evaluation, the plan, presence at the most demanding parts and availability for emergencies — and to document them. Monitored anesthesia care is reported with modifier QS, and some payers require G8 or G9 for certain patients.
Separately billable services
Arterial lines, central lines and transesophageal echocardiography may be billed separately when performed and documented. Nerve blocks for post-operative pain can be billed separately when requested by the surgeon and not used as the main anesthetic. Labor epidurals are billed by time or by the payer’s method. Groups working in several facilities need charge capture from each one, and contract rates checked by payer — see A/R management.