J Extra Corpor Technol 2025, 57, 147--152 Ó The Author( s), published by EDP Sciences, 2025 https:// doi. org / 10.1051 / ject / 2025018
Available online at: ject. edpsciences. org
TECHNIQUE OR APPLICATION
Using an intermittent flow(“ clamp and flash”) method to assess the readiness to wean from VA ECMO in adult and pediatric patients
James R Neal( CCP, FPP) 1,*, Pavel V. Mishin( MS, CCP) 1, Caitlin L. Blau( MHA, CCP) 1 Devon O. Aganga( MD) 2, and Troy G. Seelhammer( MD) 3
1 Cardiovascular Surgery, Mayo Clinic, 200 1st ST SW, Rochester, MN 55905, USA 2 Pediatric Critical Care and Pediatric Anesthesia, Mayo Clinic, 200 1st ST SW, Rochester, MN 55905, USA 3 Critical Care and Anesthesia, Mayo Clinic, 200 1st ST SW, Rochester, MN 55905, USA
Received 25 October 2024, Accepted 27 April 2025
Abstract – Background: The use of VA extracorporeal membrane oxygenation( ECMO) for cardiac recovery is widely adopted, with extensive publications on assessing readiness to wean from VA ECMO. Techniques to reduce ECMO support vary, including reducing flows to a low continuous cardiac index, adding bridges, temporary flow cessation, or decreasing ECMO RPMs. Method: We propose an alternative method involving repeated cycles of 3--4 min of ECMO flow cessation(“ clamp”) followed by a 30-second return(“ flash”) of flow. This method requires additional anticoagulation to achieve an elevated ACT, targeting 220 s for adults and 210 s for pediatrics with heparin drip and bolus, or 240 s for adults and 225 s for pediatrics with bivalirudin drip and heparin bolus. During the clamp period, flow is stopped in adult ECMO circuits with a single venous line clamp, while in pediatric circuits, flow continues via the manifold shunt but is stopped in the arterial and venous lines with a single venous line clamp. Flashing the circuit resumes patient flow for 30 s to circulate stagnant blood. Results: This method significantly reduces support during the trial, which lasts one hour for adults and up to two hours for pediatric patients. The heart is unsupported 85--90 % of the time, with an 85 % decrease in cardiac support compared to low-flow trials. Conclusion: Since 2011, our center has used this technique without thrombotic complications when the protocol is followed. Most patients removed from ECMO did not require reinstitution, with rare cases needing VV support or VA support due to sepsis onset.
Key words: VA ECMO, ECMO Weaning, Heparin, Bivalirudin. Overview
Utilization of veno-arterial( VA) extracorporeal membrane oxygenation( ECMO) for support of a patient until heart function improves has long been reported in the literature [ 1, 2 ]. The timing and necessary recovery required to wean off ECMO have also been well described. Prior studies report the conditions needed for inotropes, heart function, and blood pressure, but often leave the act of reducing ECMO support short of a full explanation [ 1--3 ]. There have been studies reporting a temporary cessation of ECMO flow that appears to be in the range of minutes, followed by low flow with cardiac indexes ranging from 0.5 to 1 cardiac index( CI) or blood flow of 1--1.5 Liters per minute( LPM) in adult patients [ 2, 3 ]. Other studies have reported allowing the revolutions per minute( RPMs) of the centrifugal pump to be down-titrated to levels low enough to
* Corresponding author: neal. james @ mayo. edu facilitate retrograde flow through the ECMO circuit, thereby generating a left-to-right shunt and subsequent diminishment of cardiac output by about 0.5--1 LPM [ 4--6 ]. While the operationalization may differ in each of these approaches, the ultimate goal of performing the turn down must be placed central to the discussion. In this context, the physiologic rationale is to diminish ECMO support to a threshold whereby ascertainment of tolerance of separation may be assessed. In some cases, such as a patient who has fully recovered cardiac function, prediction of successful separation may be straightforward. However, in many circumstances, a multitude of physiological perturbations challenge this assessment, which creates a clinical conundrum as to the potential tolerance of ECMO separation.
Staying on ECMO is not without risks, as previously published [ 7, 8 ]. The use of anticoagulants poses additional patient risk of bleeding while tempering the risk of thrombosis. Turning down the ECMO flow increases the risk of thrombosis due
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