Venepuncture practice.

This is an audio commentary probably for a film which describes the ease of administering intravenous anaesthesia. The patients are named as A, B etc. There are obvious periods of silence when the recording has been stopped (perhaps to synchronise with the footage). Judging by the very slight antipodean accent of the narrator, he is likely to be Sir Robert Reynolds MacIntosh who was one of the founder members of SAAD