Evaluation of a Portable Blood Gas Analyzer for Prehospital Triage in Carbon Monoxide Poisoning: Instrument Validation Study (Preprint)

Abstract

BACKGROUND Carbon monoxide poisoning is an important cause of morbidity and mortality worldwide. Symptoms are mostly aspecific, making it harder to identify, and its diagnosis is usually made through blood gas analysis. However, the bulkiness of gas analyzers prevents them from being used at the scene of the incident, thereby leading to the unnecessary transport and admission of several patients. While multiple wavelengths pulse oximeters have been developed to discriminate carboxyhemoglobin from oxyhemoglobin, their reliability is debatable, particularly in the hostile prehospital environment. OBJECTIVE The main objective of this pilot study was to assess whether the Avoximeter 4000, a transportable blood gas analyzer, could be considered for prehospital triage. METHODS Blood samples from an emergency department cohort of 68 patients and 12 forensic specimens were tested using the Avoximeter 4000. A standard intra-hospital blood gas analyzer (ABL827 FLEX) was used as gold standard. RESULTS The Avoximeter overestimated carboxyhemoglobin levels by a mean difference of 1.8% (95% CI 1.5-2.1) and yielded a diagnostic specificity of 95.6% (95%CI 87.0-98.6) according to commonly accepted diagnostic thresholds. CONCLUSIONS The limited difference, which erred on the side of safety, and the relatively low overtriage rate warrant further exploration of this device as a prehospital triage tool.