Utilization of low-flow ECMO in extracorporeal cardiopulmonary resuscitation: efficacy and safety

ELSO guidelines recommend an ECMO flow of at least 60 ml/kg/min in extracorporeal cardiopulmonary resuscitation (E-CPR), but there is little evidence to support this claim. Retrograde flow into the cardiac chambers during peripheral veno-arterial ECMO support leads to an increase in afterload that can worsen left ventricular functioning. For this reason, mantaining low flow during ECMO could be beneficial, and this kind of support requires smaller cannulas which leads to less vascular complications.

Our objective was to analyze the results of low-flow ECMO in a tertiary hospital.

We conducted an observational and retrospective study of the patients treated with E-CPR from 2020 to 2025 in a tertiary hospital. 45 cases were collected, from which 15 patients were excluded because of premature death (less than 48 hours). We collected demographic, clinical and analytical data, as well as vasoactive drugs use in the first 72 hours.

30 patients were included, with an average age of 59 years. The demographic characteristics and E-CPR parameters are shown in table 1.

We observed a ECMO flow median of 30 ml/kg/min [interquartile range (IQR) 28.4-37.4]. The median of arterial pressure in the first 48h was 80mmHg (IQR 86-74). The median of norepinephrine dose decreased from 0.11 ml/kg/min (IQR 0-0.22) to 0.01 (IQR 0-0.09) in the first 8h and was 0 from the first 12h onwards. The median of lactic acid at arrival was 13.3 mmol/l (IQR 7.9-16.5), the median of lactic acid clearance (<2.5 mmol/l) was 24h and 90% of patients had normal lactic acid levels at 72h. Percutaneous decannulation was possible in 78% of patients, with a percentage of vascular complications of 13%. Survival until discharge was 56.7%, in the majority of cases with a Cerebral Performance Category (CPC) of 1.

In our experience, the use of low-flow ECMO allows restoration of circulation and, afterwards, hemodynamic stability with adequate peripheral perfusion. A reduction of lactate levels and norepinephrine dose was observed within the first hours of ECMO support; with a low time until withdrawal from ECMO support and a low rate of vascular complications. Also, the survival with good neurological outcomes is similar to other publications.