A syringe (1) in the form of a ready-to-use system, the syringe (1) being packaged inside a bag (20) and comprising a syringe body (2) having - an internal chamber (3) that takes the form of a gas container and - a tip (4) connected to the internal chamber (3), - with a plunger (5a) guided in a longitudinally movable manner by the internal chamber (3), preferably with a piston rod (5 ), and - with a sealing plug (7), - a filter being attached to the syringe (6) fixed to the tip (4), and - the sealing plug (7) being fixed to the filter attached to the syringe (6) , which seals the internal chamber (3) tightly to the gases, and - in which the syringe body (12) does not have a maximum stroke mark (18) and / or one or more marks (15, 16 or 17) mixing ratio for different heavy gases； - characterized in that the internal chamber (3) is filled with a mixture of air and heavy gas in a predetermined mixing ratio, the piston rod (5) or the piston (5a), respectively, being positioned such that the mixture of air and heavy gas present in the predetermined mixing ratio can be administered immediately； and - in which the bag (20) containing the syringe (1) is empty.Una jeringa (1) en forma de un sistema listo para usar, estando la jeringa (1) envasada dentro de una bolsa (20) y comprendiendo un cuerpo de jeringa (2) que tiene - una cámara interna (3) que adopta la forma de un recipiente de gas y - una punta (4) conectada a la cámara interna (3), - con un émbolo (5a) guiado de una manera longitudinalmente desplazable por la cámara interna (3), preferentemente con una varilla de émbolo (5), y - con un tapón sellante (7), - estando un filtro unido a la jeringa (6) fijado a la punta (4), y - estando el tapón sellante (7) fijado al filtro unido a la jeringa (6), que sella la cámara interna (3) herméticamente a los gases, y - en la que el cuerpo de jeringa (12) no lleva una marca (18) de carrera máxima de émbolo y/o una o más marcas (15, 16 o 17) de proporción de mezcla para diferentes
