Conventional versus pump-controlled retrograde trial off (PCRTO) weaning in V-A ECMO: exploring feasibility, physiological insights and benefits

Abstract

Weaning from veno-arterial extracorporeal membrane oxygenation (V-A ECMO) and determining the optimal timing for liberation from mechanical circulatory support (MCS) remain critical yet complex. Although multiple weaning protocols exist, focusing on hemodynamic and echocardiographic parameters [1], no direct comparative studies have clarified which approach best reflects true cardiopulmonary reserve. Conventional weaning involves gradually reducing ECMO flow to around 1 L-per-minute (lpm), leaving 1 lpm residual right ventricular (RV) unloading and 1 lpm left ventricular (LV) afterload. In contrast, Pump-Controlled-Retrograde-Trial-Off (PCRTO) introduces controlled retrograde flow through the ECMO-pump, creating a controlled arterio-venous shunt that better mimics native physiology [2,3,4] (Fig. 1).

Fig. 1

Schematic overview indicating the flow during conventional peripheral V-A ECMO-support (left panel) and flow reversal during PCRTO (right panel). RV: right ventricle; LV: left ventricle; V-A ECMO: veno-arterial extracorporeal membrane oxygenation; PCRTO: pump-controlled retrograde trial off; rpm: revolution per minute; MAP: mean arterial pressure; P-return ECMO: return ECMO-cannula pressure

Full size image

We conducted a pilot multicentre evaluation of PCRTO’s feasibility, safety, and physiological insights compared to conventional weaning. The study was registered as service evaluation and conducted across three quaternary high-volume centres. Our cohort included 21 adult patients (mean age 49 ± 16 years; 57% male) supported with V-A ECMO for refractory cardiogenic shock (CS) between March 2023 and September 2024. Our inclusion criteria ensured that only patients demonstrating sufficient cardiopulmonary recovery and stable haemodynamics were considered for weaning. The PCRTO-protocol also incorporated regular echocardiographic assessments and invasive monitoring with a pulmonary artery catheter. Criteria for ‘readiness-to-wean’ required resolution of the underlying cause of CS, evidence of improving end-organ perfusion (renal and hepatic), serum lactate < 2 mmol/L, mean arterial pressure (MAP) > 60 mmHg, arterial pulse pressure > 15 mmHg, improving left ventricular outflow tract velocity-time integral (LVOT VTI), and absence of severe mitral or tricuspid regurgitation [5].

All patients were managed on standardized anticoagulation protocols using intravenous unfractionated heparin (UFH), targeting therapeutic anti-Xa levels. Prior to weaning, circuit integrity was thoroughly assessed to exclude thrombus formation, and distal limb perfusion was confirmed. Conventional weaning was performed first, reducing ECMO revolutions per minute (rpm) in stepwise fashion to achieve flows of 1–1.5 lpm, while closely monitoring haemodynamics and echocardiography.

For the PCRTO-procedure, additional preparatory steps were required: distal leg perfusion cannula (DPC) flow was clamped and flushed with heparinised saline, sweep gas flow was stopped to evaluate native pulmonary function, and ECMO rpm were further reduced until a controlled retrograde flow of 0.5–1 lpm was achieved and maintained for 30 min. Afterwards, if no adverse events occurred, flow was restored to anterograde. The patient was assessed for readiness-to-explant at the end of the conventional weaning phase and subsequently at the end of PCRTO. This decision was based on echo, haemodynamic and PA-catheter trends during the weaning phases (MAP, central venous and arterial oxygen saturation, LV/RV cavity diameters, wedge pressure, serum lactate etc.).

In total, 32 paired weaning trials were performed. Secondary MCS devices were used in 27% of cases (5 Impella CP, 2 intra-aortic balloon pumps). Weaning attempts were performed at a median of 6 (IQR 4.5–10) days after ECMO-initiation, with total ECMO-support duration of 9 (IQR 6–12) days. Explantation was performed within 12–24 h of a successful weaning trial.

Adverse events were rare: one DPC thrombosis during PCRTO was successfully treated without sequelae. No other thromboembolic complications, device re-initiations, or post-explant thrombotic events were observed. One patient died within 24 h of explantation due to a ventricular tachycardia storm, not attributable to the weaning technique. In our study, the PCRTO-technique has shown to be feasible and safe without increased mortality or life-threatening complications. Nevertheless, reversing the flow comes with potential risks, particularly in relation to thrombosis and embolization [2,3,4]. Therefore, a prerequisite in our study was to maintain UFH at a stable level for at least 12 h, with an anti-Xa activity above 0.3 IU/ml. If anticoagulation was deemed suboptimal, an additional bolus of UFH was administered prior to initiation of weaning. Before and after PCRTO, the circuit was checked thoroughly to detect any clots and/or fibrin formation, particularly at the access site. Additional caution was taken in the presence of shunts, e.g. patent foramen ovale, due to the possible risk of paradoxical embolism. In case of significant right-to-left shunt, PCRTO was not performed.

Discordant results on haemodynamic and respiratory stability during conventional and PCRTO weaning were seen in 13 weaning trials, impacting our clinical decision making in 61.9% of our patients (Table 1; bold italic). In nine cases (42.9%), patients appeared stable during conventional weaning but developed latent instability during PCRTO (Pass/Fail). Here, PCRTO unmasked RV failure (n = 3), biventricular compromise (n = 3), and respiratory deterioration (n = 3), prompting additional optimization before safe explantation. Indeed, the RV function is pre-load depended and afterload sensitive, and a similar physiology is observed in LV with severely reduced systolic function. PCRTO allows physicians to provide a steady and well controlled retrograde flow, challenging the RV whilst reducing the LV afterload. Moreover, during PCRTO the blood is oxygenated solely by the patient’s native lung enabling true assessment of pulmonary function. In one case, PCRTO revealed a recurrent aortic coarctation that had been underestimated during conventional weaning, enabling pre-explant repair and, again, highlighting the additional value of the PCRTO-technique challenging the cardiopulmonary system.

Table 1 Description of 32 weaning trials in 21 V-A ECMO supported cardiogenic shock patients

Full size table

Conversely, in three cases (14.3%) where conventional weaning suggested failure, PCRTO confirmed stable haemodynamics and pulmonary function (Fail/Pass), supporting safe explantation and avoiding premature escalation to durable MCS such as LVAD implantation. Once more, in scenarios with advanced cardiac disease, the reversal from cardiopulmonary unloading to a loading challenge by PCRTO added relevant information that impacted decision-making on short and long-term strategies. In 18 trials (Pass/Pass), both techniques yielded concordant results.

In conclusion, this study highlights PCRTO as a feasible, safe, and informative complement to conventional V-A ECMO weaning. Indeed, PCRTO’s capacity to restore full preload and reduce LV afterload under controlled retrograde flow provides a physiologically sound assessment of native cardiac and pulmonary function, making it a valuable adjunct in borderline cases.

Study limitations include the relatively small sample size, observational design, and lack of long-term follow-up. Despite these, the impact on clinical decision-making, ease of bedside implementation, and minimal additional risk highlight its potential role in modern V-A ECMO programs, especially for complex or borderline CS weaning scenarios.

No datasets were generated or analysed during the current study.

V-A ECMO:

Veno-arterial extracorporeal membrane oxygenation

MCS:

Mechanical circulatory support

Lpm:

Litre per minute

RV:

Right ventricle

LV:

Left ventricle

PCRTO:

Pump-Controlled-Retrograde-Trial-Off

CS:

Cardiogenic shock

MAP:

Mean arterial pressure

LVOT VTI:

Left ventricle outflow tract velocity-time-integral

UFH:

Unfractionated heparin

Rpm:

Revolutions per minute

DPC:

Distal leg perfusion cannula

LVAD:

Left ventricular assist device

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Author notes

1. Francesca Fiorelli and Christophe Vandenbriele Shared first author.

2. Alexander Rosenberg, Maurizio Passariello and Brijesh V. Patel Shared senior author.

Authors and Affiliations

1. Royal Brompton and Harefield Hospitals, Guy’s and St Thomas’ NHS Foundation Trust, Sydney Street, London, SW3 6NP, UK

   Francesca Fiorelli, Christophe Vandenbriele, Hatem Soliman Aboumarie, Georgios Georgovasilis, Tim Jackson, Ana Sofia da Costa Pinto, Olaf Maunz, Fernando Riesgo Gil, Waqas Akhtar, Vasileios Panoulas, Donna Hall, Alexander Rosenberg, Maurizio Passariello & Brijesh V. Patel

2. Cardiovascular Sciences, National Heart and Lung Institute, Imperial College, London, SW3 6LY, UK

   Vasileios Panoulas

3. St. George’s University Hospitals NHS Foundation Trust, London, SW17 0QT, UK

   Jonathan Aron & Charlie Cox

4. Anaesthetics, Pain Medicine and Intensive Care, Dept. Surgery & Cancer, Faculty of Medicine, Imperial College, London, SW3 6LY, UK

   Christophe Vandenbriele & Brijesh V. Patel

5. Cardiovascular Center, OLV Hospital Aalst, Aalst, B9300, Belgium

   Christophe Vandenbriele

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Contributions

Conceptualization and methodology performed by CV, FF, MP, and BVP. Material preparation, data collection and analysis were performed by FF, CV, MP, AR, JA, and CC. The first draft of the manuscript was written by FF and CV, all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Brijesh V. Patel.

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This study was registered as a service evaluation on each of the sites. As per local agreement, informed consent could be waived.

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Competing interests

The authors declare no competing interests.

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Fiorelli, F., Vandenbriele, C., Aboumarie, H.S. et al. Conventional versus pump-controlled retrograde trial off (PCRTO) weaning in V-A ECMO: exploring feasibility, physiological insights and benefits. Crit Care 29, 415 (2025). https://doi.org/10.1186/s13054-025-05655-6

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• Received: 01 August 2025

• Accepted: 04 September 2025

• Published: 01 October 2025

• DOI: https://doi.org/10.1186/s13054-025-05655-6

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