Patients with severe respiratory failure frequently suffer from concomitant haemodynamic compromise. By correcting respiratory acidosis and permitting reduced mechanical ventilation pressures, venovenous extracorporeal membrane oxygenation (V-V ECMO) may indirectly improve haemodynamics. The aim of this study was to assess how vasopressor requirements changed after V-V ECMO cannulation, and which factors were the primary drivers of this change.

This retrospective single-centre study included 107 consecutive adult recipients of V-V ECMO from 2010 to 2024 who required noradrenaline within 24 h before ECMO cannulation. The primary outcome was the change in Vasoactive-Inotropic Score (VIS) from Day 0 (24 h before) to Day 1 (24 h after ECMO initiation). Secondary outcomes included changes in fluid balance, ventilator settings, blood gas and laboratory parameters. A linear mixed-effects model was used to assess the effects of daily net fluid balance, mean airway pressure (P_aw), mean daily pH, arterial partial pressure of oxygen (PaO₂), arterial partial pressure of carbon dioxide (PaCO₂), mean daily propofol dose, and lactate on the VIS over time (“Day −2” to “Day +3”).

From Day 0 to Day 1, the daily mean VIS significantly decreased from a median of 14 (IQR 6, 30) to a median of 12 (5, 22). This was accompanied by significant reductions in P_aw and PaCO₂, and a significant increase in arterial pH (p < 0.001 for all). In the multivariate model, a higher arterial pH was significantly associated with a lower VIS (β = −9.2 per +0.1-unit, p < 0.001). Higher lactate was associated with higher VIS (β = 4.5, p < 0.001). Sensitivity analyses revealed more pronounced effects of pH increase on VIS reduction in patients with high noradrenaline requirements.

After initiation of V-V ECMO, a significant decrease in vasopressor requirements was observed, this benefit being directly attributable to the correction of severe respiratory acidosis.