In the early days of anaesthesia, before the advent of dedicated anaesthetists, it was common practice for a patient's anaesthetic to be administered by the surgeon's houseman. The houseman acted as a technician, the surgeon telling him how to give the anaesthetic, while at the same time operating. There are still a few old diehard surgeons who still try to do this, even with career anaesthetists.
In dentistry it was common practice until the seventies for a single handed dentist to administer an anaesthetic and then perform the dental work.
This concept of a single handed anaesthetist/operator has now long been consigned to the bin marked "unacceptable practices". However the practice has not been abandoned in the DIY sector.