Abstract: The pressurized liquid dissection apparatus has means for pressurization of working liquids and treatment liquids, controlled discharge means for a pressurized jet, and means for switching or mixing a treatment product with the working liquid or multiplexing means during pulsed mode operation of pressurized pulsed jets. The procedure consists in pressurized spraying of at least one treatment product with the pressurized surgical working jet or separately therefrom but with the same apparatus and during the same intervention so as to realize a surgical act and a therapeutic act during one and the same intervention. This invention is applicable in the surgical and medical fields.