Instantaneous carboxyhemoglobin level change due to smoking and analysis of baseline SpCO in smokers.

Background: The aim of this study was to investigate baseline carboxyhemoglobin saturation (SpCO) values in smokers and to show the relationship between SpCO and age, years smoking, cigarettes per day, and nicotine dependence. We also analyzed the changes in carboxyhemoglobin in the body during active smoking.

Methods: This prospective cohort study involved 136 outdoor smokers and 60 controls who had never smoked. SpCO, heart rate (HR), and oxyhemoglobin saturation (SpO2) values were recorded with a CO-oximeter device before, during, and two minutes after smoking. Changes during active smoking were analyzed, and all parameters were compared between smoking and non-smoking groups. Age, BMI, years smoking, cigarettes per day, and Fagerström nicotine dependence (FTND) level were correlated with baseline SpCO.

Results: The mean age of smokers was 32.3 years (70.6% male; 22.79% with comorbidities), while the mean age of non-smokers was 36.7 years (38.3% male). The SpCO and HR were significantly higher during (p = 0.006, p < 0.001) and after (p = 0.015, p < 0.001) smoking than the pre-cigarette levels. There was a significant difference between smokers (3.07) and non-smokers (1.77) in terms of baseline SpCO (p < 0.001). Correlation analysis showed that age, years smoking, and nicotine dependence were positively correlated with baseline SpCO. In the ROC analysis, the AUC value for SpCO was 0.705 and the optimal cut-off value was 1.50. In addition, 83% of smokers had a baseline SpCO value below 5%.

Conclusion: In this study, the baseline SpCO values of smokers were found to be approximately 200% higher than those of non-smokers. In addition, SpCO and HR increased during active smoking. However, 83% of smokers had a baseline SpCO below 5% and just 2 (1.47%) smokers had a baseline SpCO value above 9%, suggesting that the intoxication level of 9% in smokers should be reconsidered.

Clinical trial number: Not applicable.