Carbon dioxide in patients on veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is eliminated via respirator as well as via the oxygenator's membrane of the ECMO machine. Consequently, monitoring of end-tidal carbon dioxide tensions is limited, which can result in marked swings towards non-physiological values. Hyper- and hypocapnia, however, can have detrimental effects on organ perfusion in a great number of patients supported with VA-ECMO. Continuous, rapidly applicable monitoring of reliable carbon dioxide measures would therefore be extremely helpful to prevent harmful deviations from the norm. The investigators therefore try to assess the accuracy and the precision of continuously measured non-invasive transcutaneous carbon dioxide partial pressures when compared with tensions determined by blood gas analysis.

After documenting the characteristics of participants, cannulation site, and the cause for ECMO support, transcutaneous, arterial, venous, as well as end-tidal carbon dioxide partial pressure values are measured simultaneously at steady state conditions and compared with each other at various time points over a four-hour observation period. In addition, oxygen tensions are registered transcutaneously and in arterial and venous blood while respirator settings, sweep gas flow, ECMO flow, body temperature, volume status, and the dosage of vasopressors are also being recorded.

Inclusion Criteria:

• Low cardiac output requiring VA-ECMO support.

Exclusion Criteria:

• Age < 18 years

Patients with low cardiac output after ECMO deployment in tertiary care center.