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Updated: May 29, 2025

Expired CO2 Measurement in Intubated or Spontaneously Breathing Patients from the Emergency Department
Published on: January 29, 2011
Diagnosis of carbon monoxide exposure in clinical research and practice: A scoping review
Phil Moss1, Natasha Matthews1, Rosalie McDonald1
1St Georges' Emergency Department Clinical Research Group, Emergency Department, St Georges' Hospital, London, United Kingdom.
Objective:
To undertake a scoping review to identify methods and diagnostic levels used in determining unintentional, non-fire related carbon monoxide exposure.
Design:
Online databases and grey literature were searched from 1946 to 2023 identifying 80 papers where carbon monoxide levels were reported.
Results:
80 papers were included; 71 research studies and 9 clinical guidelines. Four methods were described: blood carboxyhaemoglobin (arterial or venous blood analysis), carbon monoxide oximetry (SpO2), expired carbon monoxide, and ambient carbon monoxide sampling. Blood analysis methods predominated (60.0% of the papers). Multiple methods of measurement were used in 26 (32.5%) of the papers. Diagnostic levels for carboxyhaemoglobin were described in 54 (67.5%) papers, ranging between 2% and 15%. 26 (32.5%) papers reported diagnostic levels that were adjusted for the smoking status of the patient.
Conclusions:
Four methods were found for use in different settings. Variability in diagnostic thresholds impairs diagnostic accuracy. Agreement on standardised diagnostic levels is required to enable consistent diagnosis of unintentional, non-fire related carbon monoxide exposure.
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