Extracorporeal membrane oxygenation or ECMO (also known as Extracorporeal Life Support or ECLS) supports patients during life-threatening situations, such as heart or lung failure due to illness, after cardiac surgery, or as a bridge for patients awaiting a lung transplant or heart assist device.
Despite ECLS being used for decades, perfusion problems continue to exist and are associated with significant morbidity and mortality.
Complications of ECMO
Some of the most serious perfusion problems include vascular, neurological, renal, hemorrhagic complications, and infection. Vascular complications (both bleeding and thrombosis) remain the leading causes of morbidity and mortality in patients treated with ECMO. Survival rates for patients following ECMO therapy in the treatment of cardiogenic shock and cardiac arrest have been reported between 20% and 65%.
During peripheral veno-arterial ECMO, large bore femoral arterial cannulation and hemodynamic instability expose limbs to significant risk for thromboembolic complications. Limb ischemia risk factors include:
- Larger cannulas (>20 Fr)
- Women and younger patients
- Presence of peripheral arterial disease
Ways to mitigate ischemic risk include vascular evaluation with Doppler ultrasound and near infra-red spectroscopy (NIRS). Some experts recommend a baseline NIRS (SpO2) of greater than 40 and a distal perfusion pressure of 50 mmHg to prevent limb ischemia. Distal perfusion catheter (DPC) placement has been shown to improve limb perfusion and reduce the incidence of limb ischemia.
Vascular injury is another serious perfusion problem that can lead to dissection, pseudoaneurysm, and retroperitoneal bleeding. These complications typically occur during the placement or removal of arterial cannulas. Vascular complications occur in 7–14% of patients and are compounded by coagulative abnormalities.
Narrow pseudoaneurysms can be managed with ultrasound-guided thrombin injection. Larger pseudoaneurysms may require surgical intervention. Meanwhile, arterial dissections are frequently asymptomatic. Dissection with arterial occlusion requires prompt differentiation from thromboembolic occlusion.
Infection rates at groin cannulation sites range from 7% to 20%. Malnourishment and obesity increase the risk of local infection. Strict aseptic technique during cannula placement, handling, and removal are critical to prevent infection.
Additional Perfusion Problems
Other problems associated with ECMO therapy include:
- Protamine reaction
- Oxygenator failure
- Blood clotting within the extracorporeal circuit
- Line separation
- Gross contamination
- Transfusion errors
- Drug errors
- Gas embolism
- Electrical or other equipment failures
It’s imperative that clinicians develop awareness of these perfusion problems and seek to establish preventive and treatment protocols.
The Oakland University Perfusion Technology Program and the University of Colorado Health Sciences Center published guidelines (found here) about perfusion problems. This resource could be used as a baseline for perfusion programs to build upon and modify to fit their clinical environment.
Management of vascular complications of extra-corporeal membrane oxygenation
Complications of extracorporeal membrane oxygenation for treatment of cardiogenic shock and cardiac arrest: a meta-analysis of 1,866 adult patients
Ten Common Perfusion Problems: Prevention and Treatment Protocols https://amsect.smithbucklin.com/JECT/PDFs/1987_volume19/issue3/ject_1987_v19_n3_schabel.pdf