RESUMO
We present a case of an anesthetic gas leak through the valve of the Selectatec back bar during a surgical procedure. The Selectatec Vaporizing System is a quick-change system consisting of anesthetic vaporizers of the 'Tec models' of the Ohmeda machine that are seated on a compatibility manifold block located on the back bar of the anesthetic machine. In order to prevent a leak and a failure of vapor delivery, the "Tec models series" can only be turned 'on' when the locking lever is turned to the 'lock' position. However in this case, the control knob was rotated despite the back bar locking mechanism not being engaged, and a gas leak developed through the unlocked valves in Selectatec back bar. The Penlon Sigma Delta Anesthetic Vaporizer (sevoflurane) in a Datex-Ohmeda Aestiva/5 anesthesia machine can be turned 'on' when the locking lever is maintained at the 'unlock' position.