ECMO and mechanical circulatory support

ECMO complications and emergencies

Reviewed Nov 2026·6 references
New· views rounded down, updated weekly

Recognition and first actions for air in the circuit, pump failure, decannulation, bleeding, LV distension, differential hypoxia, haemolysis, thrombosis, limb ischaemia and HIT.

At the bedside

Timed steps
  1. 1

    Call for help and protect the patient

    0 min

    Call the ECMO specialist/perfusionist and consultant. VV: switch the ventilator to the pre-agreed emergency settings (e.g. FiO₂ 1.0, PEEP 10–15, VT ~6 mL/kg PBW, RR 20–30). VA: prepare for CPR and vasopressors if flow stops.

  2. 2

    Air in the circuit

    0–2 min

    Clamp the return line close to the patient (then the drainage line) and stop/minimise the pump; if air may have entered the arterial circulation (VA), head-down left-side position and 100% O₂. De-airing and restart are specialist tasks. Find the source (loose connector, open port, cavitation from very negative drainage pressure).

  3. 3

    Pump or power failure

    0–2 min

    Check power and plug into mains/UPS; if the pump head or console fails, clamp, move the pump head to the hand crank and turn at the previous RPM until a back-up console is connected.

  4. 4

    Accidental decannulation

    0–2 min

    Clamp the circuit, apply firm pressure to the site, emergency ventilator settings (VV) or CPR/vasopressors (VA), activate massive transfusion, call surgeon/ECMO team for recannulation.

  5. 5

    Bleeding

    Minutes

    Find the site (cannula, surgical, airway, GI, intracranial). Check platelets, fibrinogen, anti-Xa/aPTT and TEG/ROTEM if available. Reduce or hold heparin (consultant), give platelets (often to >80–100 × 10⁹/L if bleeding) and fibrinogen (>1.5–2 g/L), consider tranexamic acid. Intracranial haemorrhage: stop anticoagulation, neurosurgical opinion.

  6. 6

    LV distension on VA

    Hours

    Signs: pulse pressure <10 mmHg, aortic valve not opening, LV dilatation/smoke on echo, pulmonary oedema. Act: lowest adequate ECMO flow, add dobutamine, avoid high afterload (MAP ~65), consider IABP or Impella venting, or atrial septostomy.

  7. 7

    Differential (north–south) hypoxia on femoral VA

    Hours

    Right radial SpO₂/ABG low while the lower body is well oxygenated. Act: improve native lung (FiO₂, PEEP, secretion clearance), or convert to V-AV (add a return limb to the IJ) or central cannulation.

  8. 8

    Haemolysis and thrombosis

    Hours

    Haemolysis: rising plasma free Hb/LDH, dark urine — check drainage pressure (too negative), clot in pump head (noise, heat), oxygenator thrombus; change component. Thrombosis: visible clot, rising ΔP, DVT at cannula sites, LV/aortic-root thrombus (VA), limb ischaemia.

Antifibrinolytic for significant bleeding

Tranexamic acid

IV
Dose
1 g over 10 min, may follow with 1 g over 8 h

Reduce dose in renal failure; watch the circuit for clot.

Anticoagulant if HIT is suspected

Bivalirudin

IV infusion
Dose
Start about 0.025–0.05 mg/kg/h; titrate to aPTT 1.5–2.5 × baseline
Range
0.025–0.2 mg/kg/h
Preparation
250 mg in 50 mL NS = 5 mg/mL
Worked example
70 kg at 0.05 mg/kg/h = 3.5 mg/h = 0.7 mL/h
Open infusion calculator

Inotrope to promote LV ejection on VA ECMO

Dobutamine

IV infusion
Dose
2.5–10 mcg/kg/min
Range
2.5–10 mcg/kg/min
Preparation
250 mg in 50 mL = 5,000 mcg/mL
Worked example
70 kg at 5 mcg/kg/min = 4.2 mL/h
Open infusion calculator

ECMO complications: recognise and respond

ComplicationHow it presentsFirst actions
Cannula-site bleedingOoze/haematoma, falling HbPressure, local haemostatics, suture review, correct coagulopathy, reduce heparin
Intracranial haemorrhagePupil change, seizures, GCS fallCT; stop anticoagulation; neurosurgery; BP control
Circuit thrombosisDark deposits, rising ΔP, falling post-oxy PO₂, rising D-dimerPlan oxygenator/circuit change; review anticoagulation, antithrombin, HIT
HaemolysispfHb >50 mg/dL, LDH ↑, red/brown urine, AKICheck drainage pressure, pump head, oxygenator; adjust flow/cannula; change component
Recirculation (VV)Pre-oxy sat ↑, patient SaO₂ ↓Reposition cannulae (tip distance), adjust flow
LV distension (VA)Pulse pressure <10, aortic valve closed, pulmonary oedemaReduce flow, inotrope, vent (IABP/Impella/septostomy)
Differential hypoxia (VA)Low right radial SaO₂Improve native lung; V-AV conversion
Limb ischaemia (femoral VA)Cold pale leg, NIRS ↓, CK ↑Distal perfusion cannula; vascular surgery; fasciotomy if compartment syndrome
InfectionNew organ dysfunction, rising inflammatory markers (fever masked)Cultures from the patient, source control, PK-guided antibiotics
HITPlatelet fall >50%, new thrombosisStop all heparin (including flushes), start DTI, send PF4 antibodies
Acquired von Willebrand syndromeMucosal bleeding despite acceptable routine testsConsider vWF assays; resolves after decannulation
AKIOliguria, rising creatinineCRRT via the circuit or separately; avoid overload
Red flag · call your senior now
Air in the return line: CLAMP NOW — arterial air on VA can cause massive stroke and coronary embolism.
Red flag
Sudden loss of flow with no power: hand crank immediately — know where it is stored.
Red flag
New neurological deficit or pupil change: CT head; intracranial haemorrhage is among the most lethal ECMO complications.
Red flag
Pink frothy ETT secretions on VA ECMO: LV distension with pulmonary oedema — urgent unloading.
Red flag
Platelets falling >50% from day 5–10 of heparin: think HIT; switch to a direct thrombin inhibitor while testing.
Pitfall
Turning up RPM to fix low flow: worsens negative pressure, haemolysis and cavitation without treating the cause.
Pitfall
Taking ABGs from the left radial or a femoral line on femoral VA: these mostly reflect circuit blood; the right radial best represents coronary/cerebral oxygenation.
Pitfall
Continuing heparin flushes after HIT is suspected: stop every heparin source.
Pearl
Everyone on the unit should know three things: where the clamps are, where the hand crank is, and each ECMO patient's emergency ventilator settings.
Pearl
A distal perfusion cannula placed at femoral VA cannulation reduces limb ischaemia; check its flow every shift.

Calculators for this topic

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).

Infusion rate from per-kg-per-hour dose

Pump rate for drugs dosed per kg per hour (insulin U/kg/h, midazolam mg/kg/h, propofol mg/kg/h, fentanyl mcg/kg/h, dexmedetomidine mcg/kg/h).

Predicted (ideal) body weight

ARDSNet predicted body weight from height and sex. Use for tidal volume, not for most drug doses.

References

  1. 1

    Tonna JE, Abrams D, Brodie D, et al. Management of Adult Patients Supported with Venovenous Extracorporeal Membrane Oxygenation (VV ECMO): Guideline from the Extracorporeal Life Support Organization (ELSO). ASAIO J. 2021;67(6):601-610.

  2. 2

    Lorusso R, Shekar K, MacLaren G, et al. ELSO Interim Guidelines for Venoarterial Extracorporeal Membrane Oxygenation in Adult Cardiac Patients. ASAIO J. 2021;67(8):827-844.

  3. 3

    McMichael ABV, Ryerson LM, Ratano D, et al. 2021 ELSO Adult and Pediatric Anticoagulation Guidelines. ASAIO J. 2022;68(3):303-310.

  4. 4

    Farkas J. ECMO. Internet Book of Critical Care (EMCrit).

  5. 5

    Thiele H, Zeymer U, Akin I, et al. Extracorporeal Life Support in Infarct-Related Cardiogenic Shock (ECLS-SHOCK). N Engl J Med. 2023;389(14):1286-1297.

  6. 6

    Møller JE, Engstrøm T, Jensen LO, et al. Microaxial Flow Pump or Standard Care in Infarct-Related Cardiogenic Shock (DanGer Shock). N Engl J Med. 2024;390(15):1382-1393.

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Weaning and decannulation

Educational reference for trained clinicians. Check doses against your hospital protocol and the patient in front of you.