Abstract

Monitoring the respiratory status of emergency department (ED) patients is a critical step to understanding their condition and monitoring their response to interventions. Endtidal carbon dioxide (ETCO2) can be determined with colorimetric capnometers or monitored quantitatively in real-time with continuous capnometry. ETCO2 monitoring is used for verifying endotracheal tube (ETT) placement, monitoring during procedural sedation, monitoring after traumatic brain injury (TBI), estimating prognosis of continued cardiopulmonary resuscitation (CPR), and detecting return of spontaneous circulation (ROSC) during cardiac arrest. Pulse oximetry, widespread in most EDs, noninvasively monitors oxygenated hemoglobin. Though it is not a good indicator of endotracheal intubation, the widespread use of pulse oximetry in the ED has reduced arterial blood gas (ABG) sampling and provided a noninvasive method of quickly titrating down fraction of inspired oxygen (FiO2) in mechanically ventilated patients. In caring for critically ill patients, the emergency clinician should be familiar with and comfortable using both pulse oximetry and capnometry, with special attention paid to the limitations of each method.

In this issue of EMCC, we discuss the use of pulse oximetry and ETCO₂ in the assessment and management of the critically ill patient in the ED.

Keywords: end-tidal carbon dioxide, ETCO2,endotracheal tube, ETT, continuous capnometry, return of spontaneous circulation, ROSC, fraction of inspired oxygen, FIO2, pulse oximetry, mechanically ventilated patients,