AUTHOR=Zhou Xiao-Fen , Yu Rong-Guo , Chen Qian , Xue Yi-Min , Chen Han 

TITLE=Performance of Lactate and CO2-Derived Parameters in Predicting Major Postoperative Complications After Cardiac Surgery With Cardiopulmonary Bypass: Protocol of a Diagnostic Accuracy Study

JOURNAL=Frontiers in Cardiovascular Medicine

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2021.724713

DOI=10.3389/fcvm.2021.724713

ISSN=2297-055X

ABSTRACT=<p><bold>Background:</bold> CO<sub>2</sub>-derived parameters are increasingly used to identify either low-flow status or anaerobic metabolism in shock resuscitation. However, the performance of CO<sub>2</sub>-derived parameters in cardiac surgical patients is poorly understood. This study aims to compare the performance of lactate and CO<sub>2</sub>-derived parameters in predicting major postoperative complications after cardiac surgery with cardiopulmonary bypass.</p><p><bold>Methods:</bold> This is a prospective, single-center, diagnostic accuracy study. All patients who receive elective cardiac surgery involving cardiopulmonary bypass will be screened for study eligibility. Blood samples will be taken for the calculation of CO<sub>2</sub>-derived parameters, including the venous-arterial difference in CO<sub>2</sub> partial pressure (PCO<sub>2</sub> gap), venous-arterial difference in CO<sub>2</sub> content to arterial-venous O<sub>2</sub> content ratio (Cv-aCO<sub>2</sub>/Ca-vO<sub>2</sub>), and venous-arterial difference in CO<sub>2</sub> partial pressure to arterial-venous O<sub>2</sub> content ratio (Pv-aCO<sub>2</sub>/Ca-vO<sub>2</sub>) at ICU admission, and 3, 6, and 12 h later. Baseline, perioperative data will be collected daily for 7 days; patients will be followed up for 28 days to collect outcome data. The primary endpoint is the occurrence of major postoperative complications. Receiver-operating characteristics (ROC) curve analysis will be carried out to assess the predictive performance of lactate and CO<sub>2</sub>-derived parameters. The performance of the ROC curves will be compared.</p><p><bold>Discussion:</bold> The performance of lactate and CO<sub>2</sub>-derived parameters in predicting major postoperative complications will be investigated in the non-sepsis population, which has not been extensively investigated. Our study will compare the two surrogates of respiratory quotient directly, which is an important strength.</p><p><bold>Trial Registration:</bold> ChiCTR, ChiCTR2000029365. Registered January 26th, 2020, <ext-link ext-link-type="uri" xlink:href="http://www.chictr.org.cn/showproj.aspx?proj=48744" xmlns:xlink="http://www.w3.org/1999/xlink">http://www.chictr.org.cn/showproj.aspx?proj=48744</ext-link>.</p>