The usual anesthesia screen is almost without exception straight, that is, it consists of three sides of a rectangle. This is certainly the simplest and the most stable design; the result is the erection, some 20 in. above the operating table, of a rigid bar having the appearance of a straight line. The surgeon, who almost invariably places an assistant between himself and the anesthetist, desires that this bar be moved as far cephalad as possible. The anesthetist, who is at a loss to understand why even the patient's head must disappear from his view and reach during abdominal surgery, hopes to locate the screen as far caudad as possible. The result is that the screen generally is placed directly over the patient's eyes; it is often pushed back after the operation has been started.
It is the surgeon's arm and elbow and those of his assistant that require room
Cole F. IMPROVED ANESTHESIA SCREEN. JAMA. 1951;147(4):318. doi:10.1001/jama.1951.73670210011007d