Beta-blockade for the treatment of refractory hypoxaemia during venovenous extracorporeal membrane oxygenation: An in-silico study.

IntroductionVenovenous extracorporeal membrane oxygenation (VV ECMO) is used for refractory hypoxemia, although despite this, in high cardiac output states, hypoxaemia may persist. The administration of beta-blockers has been suggested as an approach in this scenario, however the physiological consequences of this intervention are not clear.MethodsWe performed an in-silico study using a previously described mathematical model to evaluate the effect of beta-blockade on mixed venous and arterial saturations ($S_{\overline{v}}{O}_2$, S_aO₂), in three different clinical scenarios and considered the potential effects of beta-blockers on, cardiac output, oxygen consumption and recirculation. Additionally we assessed the interaction of beta-blockade with haemoglobin concentration.ResultsIn scenario 1: simulating a patient with high cardiac output and partial lung shunt $S_{\overline{v}}{O}_2$ decreased from increased 53.5% to 44.7% despite S_aO₂ rising from 74.2% to 79.2%. In scenario 2 simulating a patient with high cardiac output and complete lung shunt $S_{\overline{v}}{O}_2$ remained unchanged at 52.2% and S_aO₂ rose from 71.9% to 85%. In scenario 3 a patient with normal cardiac output and high recirculation $S_{\overline{v}}{O}_2$ fell from 50.8% to 25.5% and also fell from 82.4% to to 78.3%. Across the remaining modelling examples the effect on $S_{\overline{v}}{O}_2$ varied but oxygen delivery was consistently reduced across all scenarios.ConclusionThe administration of beta-blockers for refractory hypoxemia during VV ECMO are unpredictable and may reduce oxygen delivery, although this will vary with patient and circuit features. This study does not support the use of beta-blockers for this indication.