Résumé
BACKGROUND: The RAD-57 pulse CO-oximeter is a lightweight device allowing noninvasive measurement of blood carboxyhemoglobin (S-pCO). We assessed the diagnostic value of pulse CO-oximetry, comparing S-pCO values from the RAD-57 to standard laboratory blood carboxyhemoglobin (COHb) measurement in emergency department patients with suspected carbon monoxide (CO) poisoning. METHODS: This was a prospective, diagnostic accuracy study according to the Standards for the Reporting of Diagnostic Accuracy Studies criteria in consecutive adult emergency department patients with suspected CO poisoning. S-pCO was measured with the RAD-57 simultaneously with blood sampling for laboratory blood gas analysis. We made no changes to our standard management of CO poisoning. Blood COHb > 5% for non-smokers, and > 10% for smokers were applied as the reference standard. RESULTS: We included 93 subjects: 37 smokers and 56 non-smokers. CO poisoning was diagnosed in 26 subjects (28%). The S-pCO values ranged from 1% to 30%, with a median of 4% (IQR 2.7-7.3%). The COHb values ranged from 0% to 34%, with a median of 5% (IQR 2-9%). The mean differences between the COHb and S-pCO, values were -0.2% +/- 3.3% (95% limits of agreement of -6.7% and 6.3%) for the whole cohort, -0.7% (limits of agreement -7.7% and 6.2%) for the non-smokers, and 0.6% (limits of agreement -5.0% and 6.2%) for the smokers. The optimal thresholds for detecting CO poisoning were S-pCO of 9% and 6% for smokers and non-smokers, respectively. CONCLUSIONS: S-pCO measured with the RAD-57 was not a substitute for standard blood COHb measurement. However, noninvasive pulse CO-oximetry could be useful as a first-line screening test, enabling rapid detection and management of CO-poisoned patients in the emergency department.