Background

The optimal strategy of weaning veno-arterial (V-A) extracorporeal membrane oxygenation (ECMO) remains poorly described. Pump-controlled retrograde trial off (PCRTO) involves serial decremental pump revolutions until a retrograde flow from the arterial to venous ECMO cannula is achieved. It has been reported as a feasible weaning strategy in the pediatric population, but its application in adults has not been widely reported.

Methods

This was a retrospective observational study including all adult patients who underwent PCRTO during weaning from V-A ECMO at a tertiary ECMO center between January 2019 and July 2021. Hemodynamic characteristics during PCRTO and clinical outcomes were reported. The clinical and echocardiographic parameters of successful and unsuccessful PCRTO runs were compared.

Results

 A total of 57 runs of PCRTO in 36 patients were analyzed – 45 (78.9%) of the trials were successful. The median blood flow rate during PCRTO was 0.6 L/min, and the median duration of PCRTO was 240 minutes in the successful group compared with 35 minutes in the unsuccessful group. Patients who tolerated the trial had higher systolic blood pressure (105 vs 96 mmHg, p=0.042) and mean arterial pressure (78 vs 63 mmHg, p=0.008) at the end of PCRTO. The left ventricular outflow tract velocity-time integral measured during PCRTO was greater in the successful group (17.5 vs 12.9 cm, p=0.021).

Of the 35 patients who had at least one session of successful PCRTO, 31 (88.6%) ultimately underwent ECMO decannulation. In adjusted analysis, baseline alanine aminotransferase (OR 8.16, 95% CI 1.31-50.9, p=0.025) and serum creatinine (OR 7.15, 95% CI 1.04-49.2, p=0.046) were significantly associated with increased probability of successful PCRTO.

Conclusions

PCRTO is a feasible strategy for trialing off V-A ECMO with a low risk of adverse events and high rate of predicting eventual successful ECMO decannulation. Laboratory parameters that reflect the degree and recovery of end-organ ischemic injury were useful for predicting a successful PCRTO. The application of PCRTO should be studied in multi-centered studies.