Comparison of PCO2gap, SvO2 and plasmatic lactate in patients on venoarterial extracorporeal circulation support

Clinical assessment and laboratory markers provide valuable information on tissue perfusion and enhance the optimalisation of management in the treatment of patients on extracorporeal membrane oxygenation (ECMO). The PCO2 gap is a reliable marker of cardiac output (CO) and perfusion. The aim of this study was to evaluate the PCO2 gap as a marker of tissue hypoperfusion and to compare it to lactate and SvO2.

A single-center retrospective study on 131 adult cardiac patients who underwent ECMO implantation in the period between 2010 and 2021. Baseline characteristics, laboratory markers and mortality were analyzed.

There was a statistically significant difference in the plasmatic levels of lactate, SvO2 and PCO2 gap between patients that survived and those who died post ECMO implantation (3.6±3.29 vs 7.15±7.38 mmol/l, p<0.001; 69.13±9 vs 67.38±10%, p<0.001; 7.65±2.93 vs 8.34±3.71, p<0.001 respectively). There was a statistically significant difference in PCO2 gap in the first 5 arterial blood gas (ABG) samples post ECMO implantation between patients that survived and those who died (9.08±4.79 vs 10.37±5.35, p<0.003). For SvO2, this difference was not statistically significant (69.82±11.91 vs 68.51±11.72, p<0.104). There was a statistically significant but low negative correlation between SvO2 and PCO2 gap post ECMO implantation (r = ‒0.354, p<0.001).

The PCO2 gap is a valuable biomarker for monitoring tissue perfusion in patients on ECMO. It is associated with increased mortality and should be an integral part of clinical evaluation. (Tab. 1, Fig. 5, Ref. 26). Text in PDF www.elis.sk Keywords: PCO2 gap, VA-ECMO, lactate.