A Persistently High End-Tidal Carbon Dioxide Value: Can This Be Spurious?

Abstract End-tidal carbon dioxide (EtCO 2 ) monitoring has now become the standard of care not only during anesthesia but also in intensive care units for patients on mechanical ventilation, emergency department, and pre-hospital settings to confirm and monitor the correct placement of endotracheal tube. It is a non-invasive and continuous method of measuring exhaled carbon dioxide (CO 2 ). Continuous waveform capnography measures EtCO 2 and monitors ventilation. EtCO 2 often correlates with partial pressure of carbon dioxide in arterial blood (PaCO 2 ) and is a reliable indicator of PaCO 2 . A rise in EtCO 2 often implies increased production of CO 2 or decreased excretion (rebreathing, decrease ventilation) of CO 2 . We report an unusual case where the monitor malfunction per se lead to spuriously increased EtCO 2 values without any clinical cause and did not correlate with PaCO 2, thereby re-emphasizing that various monitors must always be interpreted in correlation with clinical observation.