introduction of the closed-circuit sys­ tem has to be the occasion of completely new quality standards both in anesthesia and in all related technological sectors, combined with the highest demands in terms of precision and measuring techniques. The conventional and still quite crude clinical anesthetic procedures will have to make way for much more phys­ iological, micromolecular precision techniques, which will compare with our present methods rather in the same way as a microelectrode to a spear and will allow new levels of achievement in anesthesiology. All our tasks will need to be rethought and thoroughly understood from these aspects. Some anesthesists, physiologists and engineers already see the closed-circuit system as a challenge, while for others this system will still mean a great deal of work and creativity be­ fore the problems are finally solved in the future.