Comparison of Partial Pressure of Carbon Dioxide in Arterial Blood and Transcutaneous Carbon Dioxide Monitorizaiton in Patients with Obstructive Sleep Apnea and Sleep Related Hypoventilation/Hypoxemia Syndromes

Objective There is limited number of studies conducted on the use of capnography for CO2 monitorization in sleep laboratories. In this study, it was aimed to investigate the correlation between the CO2 value measured by transcutaneous carbon dioxide (tcCO2) monitorization and partial pressure of carbon dioxide (PaCO2) levels measured with arterial blood gas analysis in patients diagnosed with obstructive sleep apnea syndrome (OSAS) and Sleep-related hypoventilation/hypoxemic syndromes (SRHHS). Materials and Methods Patients with bilevel positive airway pressure (BiPAP) treatment indication who were diagnosed with OSAS and SRHHS via polysomnography (PSG), were prospectively included in the study. Four arterial blood gas analyses were conducted from all participants (pre-and post-PSG, before and after manual bi-level positive airway pressure titration) in order to find PaCO2 levels against tcCO2 monitorization. Results Totally 30 patients with sleep-related respiratory disease (SRRD), consisting of 18 patients with OSAS and COPD, and 12 patients with OSAS and obesity hypoventilation syndrome (OHS), were included in the study. A correlation was detected between average tcCO2 level and average PaCO2 level in night PSG (r=0.600; p<0.0001). Similarly, we found a correlation between average tcCO2 level and average PaCO2 level in BiPAP titration night measurements as well (r=0.812; p=0.001). Finally, a correlation was detected between the average PaCO2 value obtained from four blood gas samples measured in both nights and the average tcCO2 value taken from two capnographies (r=0.783; p<0.001). Conclusion Comparing tcCO2 and PaCO2 values, it was determined that the average CO2 values measured by capnography correlated with the average of simultaneous arterial CO2 values measured before and after BiPAP titration