Judging readiness and running trials off VV and VA ECMO, echo criteria for VA weaning, decannulation, and care afterwards.
At the bedside
Timed steps- 1
Screen readiness (VV)
DailyImproving CXR and compliance; FiO₂ ≤0.6, PEEP ≤10, PaO₂ ≥70 mmHg on the ventilator; ventilation achievable with VT ≤6 mL/kg PBW, Pplat ≤28, RR ≤28 (ELSO criteria).
- 2
VV wean: FdO₂, then sweep
TrialReduce FdO₂ stepwise from 1.0 to 0.21 (about 20% steps) keeping SpO₂ >92% or PaO₂ ≥70; then reduce sweep by 0.5–1 L/min steps to 1 L/min; then sweep OFF (gas capped) for a trial of several hours, checking ABG, work of breathing and haemodynamics.
- 3
Screen readiness (VA)
DailyCause reversed/recovering, MAP ≥65 with pulsatility on reduced flow, low inotrope/vasopressor needs, normal lactate, adequate oxygenation on the ventilator (FiO₂ ≤0.5).
- 4
VA wean: flow reduction with echo
TrialReduce flow stepwise (e.g. 0.5–1 L/min steps) to ~1–1.5 L/min with adequate anticoagulation. At minimum flow, echo predictors of success in one cohort: LVEF >20–25%, aortic VTI ≥10 cm, lateral mitral annulus peak systolic velocity (TDSa) ≥6 cm/s; plus stable MAP and no RV dilatation.
- 5
Decannulate
DecidePlan with the team: stop heparin per protocol beforehand; VV cannulae are usually removed percutaneously with a purse-string/figure-of-8 suture and pressure; the VA arterial cannula usually needs surgical repair or a closure device. Have blood available.
- 6
Post-decannulation care
AfterDuplex for cannula-associated DVT (common), limb checks after arterial decannulation, restart thromboprophylaxis when safe, watch for re-deterioration, start rehabilitation and family follow-up.
Adjunct to facilitate VA weaning (selected)
Levosimendan
- Dose
- 0.05–0.2 mcg/kg/min for 24 h, no bolus
- Range
- 0.05–0.2 mcg/kg/min
- Preparation
- 12.5 mg in 500 mL D5W = 25 mcg/mL
- Worked example
- 70 kg at 0.1 mcg/kg/min = 16.8 mL/h
Inodilator for RV/LV support during weaning
Milrinone
- Dose
- 0.125–0.5 mcg/kg/min (no load)
- Range
- 0.125–0.5 mcg/kg/min
- Preparation
- 10 mg in 50 mL = 200 mcg/mL
- Worked example
- 70 kg at 0.375 mcg/kg/min = 7.9 mL/h
Conditions for a VV weaning trial (ELSO 2021)
| Domain | Intubated | Non-intubated |
|---|---|---|
| Oxygenation | FiO₂ ≤60%, PEEP ≤10, PaO₂ ≥70 mmHg | PaO₂ ≥70 on ≤6 L/min nasal cannula/face mask, or HFNC ≤40 L/min with FiO₂ ≤0.3 |
| Ventilation | VT ≤6 mL/kg PBW, Pplat ≤28, RR ≤28; acceptable pH/PaCO₂ without excessive work of breathing | Acceptable pH without excessive work of breathing |
| Radiology | Improving chest X-ray | Improving chest X-ray |
Echo predictors of successful VA weaning at minimal flow
| Parameter | Favourable value |
|---|---|
| LVEF | >20–25% |
| Aortic VTI | ≥10 cm |
| Lateral mitral annulus TDSa | ≥6 cm/s |
| RV | Not dilated; function preserved |
| Haemodynamics | MAP ≥65, pulsatile, stable lactate |
From Aissaoui et al. 2011 (single-centre cohort); combine with clinical judgement.
Calculators for this topic
Predicted (ideal) body weight
ARDSNet predicted body weight from height and sex. Use for tidal volume, not for most drug doses.
Tidal volume from predicted body weight
Lung-protective tidal volume (usually 6 mL/kg PBW; range 4-8).
PaO₂/FiO₂ ratio
Oxygenation ratio with ARDS severity bands (Berlin; PEEP ≥ 5 cmH₂O).
Infusion rate from mcg/kg/min
Pump rate in mL/h for drugs dosed in mcg/kg/min (noradrenaline, adrenaline, dobutamine, milrinone, nitroglycerin by weight).
References
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VV ECMO weaning trial
Step 1 of ~3
ELSO-based gas-weaning pathway with preserved blood flow.
Decision: Meets ELSO trial conditions (FiO₂ ≤0.6, PEEP ≤10, PaO₂ ≥70, VT ≤6 mL/kg, Pplat ≤28, RR ≤28, improving CXR)?
Based on Tonna JE, Abrams D, Brodie D, et al. Educational use; follow local protocol.
Pathophysiology
VV weaning tests whether the native lungs can oxygenate and clear CO₂ at safe ventilator settings. VA weaning tests whether the native heart can generate adequate output against normal afterload — reducing flow increases preload and lowers afterload, unmasking true LV/RV function.
Evidence
- ELSO VV 2021 provides explicit weaning-trial conditions and a gas-flow weaning sequence with preserved blood flow.
- VA weaning: Aissaoui et al. (2011) found that at minimal flow, aortic VTI ≥10 cm, LVEF >20–25% and TDSa ≥6 cm/s predicted successful weaning.
- Levosimendan has been associated with better VA weaning success in observational cohorts; randomised data are limited.
Controversies
- Duration of sweep-off trials (2 h vs 24 h).
- Decannulation while intubated vs after extubation on ECMO.
- Pump-controlled retrograde trial off (PCRTO) for VA weaning — limited evidence.
🇮🇳 India notes
- Financial pressure to decannulate early is real for many families; still follow objective criteria — failed early decannulation followed by recannulation is costlier and more dangerous.
- Arrange vascular surgical support for VA arterial decannulation in advance.
References
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