Effect of high atmospheric carbon dioxide concentrations on the serum total carbon dioxide measurement

• Main Authors: Jirapa Kerdmongkol, Pornpen Srisawasdi, Nalinee Kumproa, Sirirat Promnuch, Somlak Vanavanan, Apirom Vongsakulyanon
• Other Authors: Faculty of Medicine, Ramathibodi Hospital, Mahidol University
• Format: Article
• Published: 2020
• Subjects: Medicine
• Online Access: https://repository.li.mahidol.ac.th/handle/123456789/59199
• Institution: Mahidol University

© JOURNAL OF THE MEDICAL ASSOCIATION OF THAILAND. Background: Serum total carbon dioxide (TCO2) measurements are easily affected by numerous factors. Whether an irregularly high atmospheric CO2 concentration affects the TCO2 measurement remains unclear. Materials and Methods: In Somdech Phra Debaratana Medical Center laboratory (SDMC) and the main building laboratory (Building 1) located within Ramathibodi Hospital, Mahidol University, Bangkok, Thailand, the repeated TCO2 measurements using an enzymatic assay in three levels of human based control material were performed every two hours, over a one-day period. TCO2 in a total of 150 patient sera were measured. Simultaneously, atmospheric CO2 levels were determined. Results: Atmospheric CO2 levels in SDMC and Building 1, ranged from 763 to 1, 560 ppm and 602 to 787 ppm, respectively. Repeated TCO2 measurements for SDMC, the measured TCO2 concentrations of all control materials clearly increased between 10:00 a.m. and 4:00 p.m., with the peak at 2:00 p.m., which was related to an increase in the atmospheric CO2 concentration. By contrast, in Building 1, the measurements were considerably stable. Moreover, considering patient data (n=12, 042), the estimate median TCO2 concentration in SDMC was likely to increase between 10:00 a.m. to 4:00 p.m. as well. The association between the bias (y), difference TCO2 concentration obtained between the SDMC and the Building 1, and the increasing atmospheric CO2 (x) was y = 0.0038x - 0.016, R2=0.6813. Using regression equations, TCO2 level increased by approximately 0.4 mmol/L for every 100 ppm of CO2 increase in atmosphere. Conclusion: High atmospheric CO2 concentrations can result in falsely high TCO2 values, which may lead to markedly wrong interpretations, especially in patients with a tendency to have low TCO2 concentrations.