Human Perception: The Way We See Things

Abstract

At the end of an uneventful operation maintained by a total intravenous anesthesia (TIVA), a patient starts to buck unconsciously trying to expel the endotracheal tube. Patient movement prompts the anesthesiologist to switch the anesthesia machine from a mandatory to a spontaneous breathing mode. She does this by first selecting the new ventilation mode from the software menu and then pressing a button to activate it. While doing so, the anesthesiologist turns her attention briefly to an unrelated concurrent problem. Shortly after, the anesthesiologist returns her attention to the patient and gets the impression that he is breathing spontaneously: Chest excursions are regular; the capnography curve (expired CO₂) displays a regular pattern; the expiratory minute volume is adequate; and the oxygen-blood saturation remains stable at 100 %. Again, the patient starts to buck and the anesthesiologist decides to extubate the patient. Shortly after extubation, the oxygen-blood saturation begins to drop, and the patient turns cyanotic. It is then that the anesthesiologist realizes that the ventilator is still working in the volume-controlled mode and had not been successfully switched to the spontaneous breathing mode as she intended. She begins to mask ventilate the patient until the patient starts breathing spontaneously a few minutes later.