Pump-controlled retrograde trial off in veno-arterial extracorporeal membrane oxygenation weaning: a scoping review of physiological rationale, protocol heterogeneity, and clinical application

Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is increasingly used for refractory cardiogenic shock; however, strategies to assess readiness for decannulation remain poorly defined. Although pump-controlled retrograde trial off (PCRTO) is a novel weaning assessment, its conceptual basis and clinical role remain unclear. This scoping review aimed to map the existing evidence on PCRTO in V-A ECMO, focusing on its methodological definition, implementation, monitoring strategies, and reported outcomes, and to identify key knowledge gaps. We conducted a scoping review following the established methodological guidelines and Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews checklist. Using the Patient–Concept–Context framework, we included studies involving neonatal, pediatric, and adult patients supported with V-A ECMO who underwent PCRTO. MEDLINE, Embase, CENTRAL, and ClinicalTrials.gov were searched from inception without language or date restrictions. Two reviewers (YI and HM) independently screened studies and extracted data using a standardized charting form, and the findings were descriptively summarized. Twenty-one studies were included, predominantly case reports and case series, with limited observational data. PCRTO protocols substantially varied across studies, including differences in retrograde flow targets (commonly −0.5 to −1.0 L/min or −5 to −10 mL/kg/min), trial duration (minutes to several hours), and circuit management. Monitoring approaches were heterogeneous and frequently incorporated hemodynamic, metabolic, and echocardiographic parameters. Successful weaning was commonly reported; however, definitions of outcome and adverse events were inconsistent. PCRTO is a conceptually distinct weaning assessment in V-A ECMO that may provide additional physiological information beyond conventional flow reduction, particularly in evaluating right ventricular reserve. However, its definition, optimal protocol, and clinical effectiveness remain to be established. Further studies are required to standardize its physiological framework and clarify its role in V-A ECMO weaning.