Valve Failure in the Gas Monitor: An Unusual Cause of Falsely Low Capnography Values Under General Anesthesia: A Case Report.

We present a case in which the Dräger Primus (Dräger Medical AG&Co KG, Lüberck, Germany) anesthesia monitor displayed false readings of low end-tidal carbon dioxide (EtCO2) immediately after intubation. The patient's physical examination, vital signs, and arterial blood gases were normal. The ventilator, circuit, gas sample line, and water trap appeared intact and functional.