End-tidal Carbon Dioxide Measurements in Unintentional Non-fire-related Carbon Monoxide Poisoning

Poisoning with carbon monoxide occurs occasionally worldwide, and the gold diagnostic standard is to measure carboxyhemoglobin level in the blood. This study investigated the correlation between carboxyhemoglobin and the end-tidal carbon dioxide levels in 50 patients with carbon monoxide poisoning.

We recruited 50 volunteer patients who had been admitted to the Emergency Services of Istanbul Medipol University Hospital between January 2017 and January 2018. They had been diagnosed with carbon monoxide poisoning unrelated to fire accidents. The arterial and venous blood gases, and other blood and clinical parameters were also measured. The patients’ end-tidal carbon dioxide levels were measured from the nose and mouth air, using a Capnostream 20p bedside monitor. Pearson’s correlation analyses were performed and the results were compared with the end-tidal carbon dioxide, carboxyhemoglobin and oxygen saturation in the arterial and venous blood samples.

The Mean±SD age was 33.98±10.89 years. The Mean±SD arterial and venous carboxyhemoglobin values were 18.05±7.10 and 12.11±9.67, respectively. There were no statistically significant differences between the oxygen saturation, and the arterial and venous blood levels of carboxyhemoglobin (P=0.870, P=0.950), respectively. Also, no statistically significant correlations were found between the end-tidal carbon dioxide, and the arterial and venous carboxyhemoglobin levels (P=0.529, P=0.601), respectively.

The results from the blood analyses demonstrated that there was no statistically significant difference between the end-tidal carbon dioxide and the carboxyhemoglobin levels in these patients who had been earlier diagnosed with carbon monoxide poisoning, unrelated to fire accidents.