ECMO Troubleshooting

OVERVIEW

Approach to problems specific to patients requiring ECMO therapy

• high free hemoglobin level (normal is <0.1g/dL)
• access insufficiency
• bleeding from ECMO cannula site
• pump failure
• unintended ECMO decannulation

HIGH FREE HAEMOGLOBIN LEVEL

• Look for intravascular haemolysis
  — dark/red urine or CRRT effluent with high K+
•  Circuit should be assessed for signs of malfunction:
  — “noisy” pump head (pump head thrombosis), visible access insufficiency, or high transmembrane pressure gradient (oxygenator thrombosis)
•  If clinical evidence of haemolysis or circuit malfunction
  -> rapid response contact ICU Consultant immediately
•  If neither present -> repeat free Hb level
• if >0.10 g/dL -> likely low level haemolysis
  — access insufficiency without visible kicking (may require echocardiography to detect venous “suck-down” with a multistage cannulae)
  — vessel- cannula impingement due to pericardial collection or retroperitoneal haematoma
  — excessive speed settings with small cannulae (greater than 4000 RPM)

 ACCESS INSUFFICIENCY

Identify:

• visible access insufficiency = shaking of access line (‘kicking’)
• access insufficiency without visible kicking may cause haemolysis (high free Hb) and may require echocardiography to detect venous “suck-down” with a multistage cannulae

Seek and treat for causes:

• Hypovolaemia/Bleeding
• Poorly sited access cannula (too low)
• Cardiac tamponade (common post sternotomy)
• Excessive RPM setting (pump speed)
• Patient coughing or straining
• Positional (e.g. after turning the patient)
• Acute vasodilatation (e.g. sedation bolus)
• Increased intra-abdominal pressure
• Severe aortic regurgitation or severe pulmonary haemorrhage (VA ECMO)

BLEEDING FROM CANNULA SITE

Management:

• Fully insert the cannula to the taper
• Thrombotic (Kaltostat) dressings
• Pressure (sand bag)
• Cessation of heparin
• Vascular surgical review
• Repair and re-cannulation

Correct bleeding diathesis:

• platelets >80
• cryoprecipitate 5-10 ml/kg (1 bag ~ 20mL) -> fibrinogen >1.5
• FFP -> INR <1.5
• protamine 1mg/ 100 units of heparin in past 2 hours (max dose 50 mg)

PUMP FAILURE

Causes

• Pump head/centrifugal pump disengagement
• Electrical motor failure – either console or pump head
• Battery failure (no AC power connected)
• Rotaflow Power Isolation Switch “OFF”

Management

• Clamp circuit
• Call for help. Contact ICU Consultant and ECLS Coordinator
• Examine for cause:
  — Console (front): Power (On/Off Switch)
  — Console (front): AC Power Supply Indicator lights
  — Console (rear): Power Isolation Switch
  — External Drive: Pump head position
• Address Cause and re-establish pump function or obtain new console
• Engage Emergency Drive Unit (“Hand-crank”)
  — Transfer Pump Head to Emergency Drive Unit
  — Rotate hand crank to 1000 rpm and remove circuit clamp
  — Gradually increase revs to previous speed
• Transfer to new console
  — Ensure power to new console
  — Clamp circuit
  — Transfer Pump Head to new console
  — Establish pump speed to 1000 rpm and remove circuit clamp over 3-5 seconds while increasing pump speed to obtain full flow

UNINTENDED EMCO DECANNULATION

Effects:

• bleeding from the cannula insertion site.
• ECMO support will stop -> same as pump failure
• Access cannula decannulation: air will rapidly enter and extensively de-prime the ECMO circuit and may reach the patient (see air embolism)
• Return cannula decannulation: Patient’s blood volume will rapidly be lost from the circuit until the circuit is clamped.

AIR EMBOLISM

• watch this space!

CARDIAC ARREST

• watch this space!

References and Links

LITFL

• CCC – Everything ECMO
• CCC – ECMO troubleshooting
• CCC – Pharmacokinetics and ECMO
• CCC – Own the ECMO (presentation by Hergen Buescher, 2011)

Journal articles

• Sidebotham D. Troubleshooting adult ECMO. J Extra Corpor Technol. 2011 Mar;43(1):P27-32. PMID: 21449237