Appropriate timing of veno-arterial extracorporeal membrane oxygenation initiation after cardiac surgery

Abstract
Background
Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) can be initiated during cardiac surgery or later in ICU according to the hemodynamic profile and organ perfusion. Our aim was to study the appropriate timing of post-cardiotomy ECMO (PC-ECMO) initiation. We retrospectively analyzed 152 adult patients supported with PC-ECMO in our cardiac center between 2016 and 2022. The patients were divided into two groups: the intra-operative ECMO and the postoperative ECMO groups. The primary outcome was all-and-on-ECMO hospital mortality. The secondary outcomes included ECMO duration, new need for dialysis, cerebrovascular stroke, and length of ICU stay.

Results
Our cohort analysis revealed that 81(53.3%) patients were intra-operatively supported with VA-ECMO while 71(46.7%) patients were postoperatively supported in ICU. The postoperative ECMO group had significantly lesser SAVE score (p = 0.001), higher SAVE risk classes (p < 0.001), and higher SOFA score (p = 0.008) compared to the intra-operative ECMO group. The postoperative ECMO group had significantly more frequent hospital mortality (p = 0.003), on-ECMO mortality (p = 0.006), cerebrovascular stroke (p = 0.034), acute renal failure requiring dialysis (p < 0.001), and lesser lactate clearance at 12 h (p = 0.016) and at 24 h (p = 0.023) compared to the intra-operative group. There were statistically insignificant differences between the two groups regarding post-ECMO hospital mortality, cerebral bleeding, limb ischemia, ECMO, and ICU duration. Postponed postoperative ECMO insertion was associated with an increased risk of death (HR 1.628, 95%CI 1.102–2.403, p =0.014) with cox-proportional hazard regression. Logistic multivariable regression showed that atrial fibrillation (OR 6.2, 95% CI 2.71–61.84, p = 0.002), initial SOFA score (OR 1.46, 95% CI 1.041–3.83, p = 0.001), and postoperative ECMO insertion (OR 1.93, 95% CI 1.04–8.73, p = 0.031) were the predictors of hospital mortality.

Conclusions
Postponed ECMO insertion in critically sick patients was associated with increased mortality after cardiac surgery. Early intra-operative initiation of PC-ECMO may have the potential to improve outcomes after cardiac surgeries.