The loss of pipeline pressure in a central gas supply system is a rare but potentially hazardous complication in anaesthesia and critical care. In an anaesthesia simulator study, reactions of 20 anaesthetists to this simulated critical incident were monitored and evaluated. A comparison between novice (n = 10) and experienced anaesthesia residents/consultants (n = 10) determined a significantly quicker and more on-target reaction by the experienced anaesthetists. Unlike older cycle system anaesthesia machines, update anaesthesia ventilators (CICERO EM, Dräger, Lübeck) do not permit manual ventilation of a patient in a "closed-system" once pipeline pressure drops to zero. In this highly hazardous event, the patient has to be ventilated by reservoir bag until a sufficient back-up system delivering high inspiratory oxygen concentrations can be installed, because he is otherwise prone to diffusion hypoxia. Installation of mandatory (anaesthesia-machine integrated) back-up systems for respirators without cycle systems would therefore increase patient safety. A general algorithm for loss of pipeline pressure can be described only after a back-up system has been installed.