22-year-old patient who has severe medical problems is placed under general anesthesia by an anesthetist for a service not usually requiring anesthesia. what modifier would be appended to the service?

The modifier that would be appended to the service is Modifier 23 since Modifier 23 may be reported to describe a procedure not usually requiring anesthesia (either none or local) - but due to unusual circumstances general anesthesia is necessary.

To add, Modifier 23 is appended following the main anesthesia modifier.