[Anaesthesia tube constriction. Small defect--serious effect].

After a problem-free induction of anaesthesia for an elective aortocoronary bypass operation in a 64-year-old female patient, recurrent ventilation problems occurred. An externally intact but internally damaged anaesthesia tube caused an expiratory stenosis of varying extent. Based on this case, the safety of the algorithms for difficult ventilation, the knowledge necessary for a possible differential diagnosis, the necessity for knowledge on the alarm procedure of the anaesthesia apparatus, as well as strategies for risk reduction will be discussed.