Prospective randomized evaluation of transcutaneous carbon dioxide monitoring during complex electrophysiological procedures under deep sedation: the TRACES trial

The field of interventional electrophysiology is rapidly growing. For safe and efficient procedures sedation is needed for patient comfort and immobility. However, sedative and analgesic agents can induce respiratory depression, risking hypercapnia, hypoxia, and hypotension. This study evaluates the impact of adding transcutaneous carbon-dioxide (CO ) monitoring to standard monitoring practices in electrophysiological procedures under deep sedation. This prospective, randomized study at Ulm University Heart Center included 726 patients undergoing treatment under deep sedation between August 2019 and October 2023. Patients were randomly assigned to standard monitoring or standard monitoring with continuous transcutaneous CO monitoring (TCM-group). Standard monitoring involved non-invasive blood pressure, oxygen saturation (SpO ), and frequent peripheral venous blood gas analysis. The primary composite endpoint was SpO dips below 90% and pathological changes in venous blood gas analysis. The TCM-group included 357 patients, and the standard group had 348. The primary composite endpoint was reached by 195 patients (54.8%) in the TCM-group and 195 patients (56.5%) in the standard group (p = 0.642). However, peripheral venous CO partial pressure increased by more than 30% from baseline more often in the standard group than in the TCM-group (p = 0.005). Additionally, a venous pH below 7.25 was more common in the standard group (p = 0.047). While transcutaneous CO monitoring offers no significant benefit for the primary combined endpoint over standard monitoring during electrophysiological procedures, it helps mitigate significant CO elevations and respiratory acidosis. ClinicalTrials.gov, NCT04038476, 29 July 2019.