Concept Map: AKI in ECMO

 

Concept Map of pathophysiology related to AKI in a patient on ECMO- created by Dr. Purva Sharma using biorender.com 

Topic Discussion: ECMO and the Kidney

Extracorporeal membrane oxygenation (ECMO) is an effective therapy for patients with reversible cardiac and/or respiratory failure. AKI  often occurs in patients supported with ECMO; it frequently evolves into chronic kidney damage or end-stage renal disease and is associated with a reported 4-fold increase in mortality rate. What are the mechanisms of injury of AKI with ECMO?

This table below summarizes what might be the potential causes.

Here is a nice reference

Patient-related variables
Pretreatment factors	Hypoperfusion, loss of autoregulation Hypoxia
	Nephrotoxic drugs Systemic inflammation
ECMO-related variables
Hemodynamic factors	Blood flow alterations
Hormonal factors	Renin-angiotensin-aldosterone dysregulation ANP downregulation
ECMO-related	Blood shear stress
Systemic inflammation	Exposure to a non-self membrane Blood/air interface
Organ crosstalk	Cardio-renal syndrome
Circuit-related factors	Hypermyoglobinemia
	Embolism
	Hemolysis

Hemolysis is an interesting cause. This is an image of a patient getting CRRT on ECMO.  CRRT was on a zero K bath and high clearance rates. Within hours of starting CRRT, effluent bags of the CRRT turn red. Despite being on max CRRT,  patient’s potassium rose to 9mmol/L. This is hemolysis and can be reported in 18% of cases with ECMO.  Rhabdomyolysis can also be noted in some cases. Checking a free Hgb and effluent myoglobin can aid diagnosis for both entities. In addition, classic markers for hemolysis such as LDH, haptoglobin, anemia and so forth should be checked regularly. 

 https://www.ncbi.nlm.nih.gov/pubmed/26606144

 https://www.ncbi.nlm.nih.gov/pubmed/28470926