End-Tidal CO2 Monitoring

What Is End-Tidal CO2 Monitoring?

End-tidal CO2 monitoring (ETCO2 or capnography) is the continuous or periodic measurement of carbon dioxide concentration in exhaled breath, displayed as a numerical value (35–45 mmHg is normal in a healthy breathing person) or as a waveform tracing (capnograph). It is used primarily to confirm and monitor endotracheal tube placement — a tube in the trachea shows a sustained ETCO2 reading (typically >15 mmHg after intubation), while a tube in the esophagus shows a rapid drop or absence of ETCO2. During cardiac arrest and CPR, ETCO2 is monitored continuously to assess chest compression quality (higher ETCO2 suggests better perfusion) and to detect return of spontaneous circulation (ROSC), which appears as an abrupt rise in ETCO2 from the compressed value (often 10–20 mmHg during compressions) back to a normal range.

Why End-Tidal CO2 Monitoring Matters on the Fireground

A misplaced endotracheal tube (in the esophagus instead of the trachea) can result in no ventilation and death, and physical exam alone is unreliable for detection — capnography is the gold standard for confirmation and is the most critical safety check after intubation. During cardiac arrest, ETCO2 trending can reveal whether compressions are effective, and an abrupt ETCO2 rise may signal ROSC before a pulse check confirms it, allowing the team to stop compressions and reassess.

Relevant NFPA Standards

• NFPA 455: Standard for Emergency Medical Services (EMS)
• NREMT Standards: National Registry of Emergency Medical Technicians Practice Standards

Field Procedures & Tactical Steps

1. After intubating a patient, immediately attach a capnometer or waveform capnograph to the endotracheal tube adapter or the tube itself.
2. Observe the ETCO2 reading or waveform for at least 6 breaths — a sustained reading of 15+ mmHg confirms tracheal placement; a reading below 5 mmHg or a rapid drop suggests esophageal placement and the tube should be withdrawn and re-evaluated.
3. During cardiac arrest, monitor ETCO2 continuously during chest compressions — readings below 10 mmHg may indicate inadequate compression depth or rate, prompting reassessment of technique.
4. Watch for an abrupt rise in ETCO2 during CPR (often a sudden jump to 30+ mmHg) — this may indicate return of spontaneous circulation (ROSC), and you should pause compressions briefly to check for a pulse.
5. Communicate ETCO2 readings to the receiving hospital during transport, and note any significant changes (rising, falling, or sudden spikes) in your patient report.

Common Context & Application

ETCO2 monitoring is used on every intubated patient and every cardiac arrest receiving CPR. The monitor is attached to the endotracheal tube (via an inline adapter) immediately after intubation, or held near the mouth/nose of a spontaneously breathing patient, and readings are communicated on scene and during transport to the receiving hospital.

Frequently Asked Questions about End-Tidal CO2 Monitoring