Respiratory quotient estimations as additional prognostic tools in early septic shock

• Published in: Journal of clinical monitoring and computing 2018-12, Vol.32 (6), p.1065-1072
• Main Authors: Mesquida, J., Saludes, P., Pérez-Madrigal, A., Proença, L., Cortes, E., Enseñat, L., Espinal, C., Gruartmoner, G.
• Format: Article
• Language: English
• Subjects: Anesthesiology; Carbon dioxide; Correlation analysis; Critical Care Medicine; Health Sciences; Hemoglobin; Hypoxia; Intensive; Medicine; Medicine & Public Health; Mortality; Original Research; Oxygen content; Patients; Regression analysis; Restoration; Sepsis; Statistics for Life Sciences
• ISSN: 1387-1307; 1573-2614
• DOI: 10.1007/s10877-018-0113-8

Central venous-to-arterial carbon dioxide difference (P cva CO 2 ), and its correction by the arterial-to-venous oxygen content difference (P cva CO 2 /C av O 2 ) have been proposed as additional tools to evaluate tissue hypoxia. Since the relationship between pressure and content of CO 2 (CCO 2 ) might be affected by several factors, some authors advocate for the use of C cva CO 2 /C av O 2 . The aim of the present study was to explore the factors that might intervene in the difference between P cva CO 2 /C av O 2 and C cva CO 2 /C av O 2 , and to analyze their association with mortality. Observational study in a 30-bed mixed ICU. Fifty-two septic shock patients within the first 24 h of ICU admission were studied. After restoration of mean arterial pressure, hemodynamic and metabolic parameters were evaluated. A total of 110 sets of measurements were performed. Simultaneous P cva CO 2 /C av O 2 and C cva CO 2 /C av O 2 values were correlated, but agreement analysis showed a significant proportional bias. The difference between P cva CO 2 /C av O 2 and C cva CO 2 /C av O 2 was independently associated with pH, S cv O 2 , baseline C cva CO 2 /C av O 2 and hemoglobin. A stepwise regression analysis showed that pH was the single best predictor for the magnitude of such difference, with very limited effect of other variables. At inclusion, variables associated with ICU-mortality were lactate, pH, P cva CO 2 /C av O 2 , and the difference between P cva CO 2 /C av O 2 and C cva CO 2 /C av O 2 . Initial S cv O 2 , P cva CO 2 , C cva CO 2 /C av O 2 , and cardiac index were not different in survivors and non-survivors. In a population of early septic shock patients, simultaneous values of P cva CO 2 /C av O 2 and C cva CO 2 /C av O 2 were not equivalent, and the main determinant of the magnitude of the difference between these two parameters was pH. The P cva CO 2 /C av O 2 ratio was associated with ICU mortality, whereas C cva CO 2 /C av O 2 was not.