The words tijera and tijeras can be used interchangeably in Spanish to refer to a single pair of scissors.
Both IV sedation (twilight) and general anesthesia are used commonly for cosmetic or plastic surgery. Regardless of technique, the patient's vital signs must be monitored, which include but not limited to heart rate, blood pressure, and breathing rate.
There are quite a few other drugs that can be used for IV sedation. But in practical terms, most of the time a single benzodiazepine, usually midazolam, is used. This is especially true in the UK, where polydrug use is discouraged (even though it is not illegal). A typical IV session takes up to 1 1/2 hours.