Time course, factors related to, and prognostic impact of venoarterial extracorporeal membrane flow in cardiogenic shock

Abstract

Abstract Aims Venoarterial extracorporeal membrane oxygenation (VA‐ECMO) is currently one of the most used devices in refractory cardiogenic shock. However, there is a lack of evidence on how to set the ‘optimal’ flow. We aimed to describe the evolution of VA‐ECMO flows in a cardiogenic shock population and determine the risk factors of ‘high‐ECMO flow’. Methods and results A 7 year database of patients supported with VA‐ECMO was used. Based on the median flow during the first 48 h of the VA‐ECMO run, patients were classified as ‘high‐flow’ or ‘low‐flow’, respectively, when median ECMO flow was ≥3.6 or <3.6 L/min. Outcomes included rates of ventilator‐associated pneumonia, ECMO‐related complications, days on ECMO, days on mechanical ventilation, intensive care unit and hospitalization lengths of stay, and in‐hospital and 60 day mortality. Risk factors of high‐ECMO flow were assessed using univariate and multivariate cox regression. The study population included 209 patients on VA‐ECMO, median age was 51 (40–59) years, and 78% were males. The most frequent aetiology leading to cardiogenic shock was end‐stage dilated cardiomyopathy (57%), followed by acute myocardial infarction (23%) and fulminant myocarditis (17%). Among the 209 patients, 105 (50%) were classified as ‘high‐flow’. This group had a higher rate of ischaemic aetiology (16% vs. 30%, P = 0.023) and was sicker at admission, in terms of worse Simplified Acute Physiology Score II score [40 (26–58) vs. 56 (42–74), P < 0.001], higher lactate [3.6 (2.2–5.8) mmol/L vs. 5.2 (3–9.7) mmol/L, P < 0.001], and higher aspartate aminotransferase [97 (41–375) U/L vs. 309 (85–939) U/L, P < 0.001], among others. The ‘low‐flow’ group had less ventilator‐associated pneumonia (40% vs. 59%, P = 0.007) and less days on mechanical ventilation [4 (1.5–7.5) vs. 6 (3–12) days, P = 0.009]. No differences were found in lengths of stay or survival according to the ECMO flow. The multivariate analysis showed that risk factors independently associated with ‘high‐flow’ were mechanical ventilation at cannulation [odds ratio (OR) 3.9, 95% confidence interval (CI) 2.1–7.1] and pre‐ECMO lactate (OR 1.1, 95% CI 1.0–1.2). Conclusions In patients with refractory cardiogenic shock supported with VA‐ECMO, sicker patients had higher support since early phases, presenting thereafter higher rates of ventilator‐associated pneumonia but similar survival compared with patients with lower flows.

Keywords

• Cardiogenic shock
• Extracorporeal membrane oxygenation
• ECMO flow
• Mechanical ventilation
• Outcome