Albumin, COP and Endothelial Damage in Patients With ESLD Undergoing OLT

Patients suffering from end-stage liver disease (ESLD) are critically ill. Still, therapeutic options are limited, no organ replacement procedure is available and orthotopic liver transplantation remains the unique therapy of choice.

ESLD is associated with a myriad of comorbidities, and is characterized by imbalances in the acid-base- status, coagulopathy, metabolic disorders and activation of the pro-inflammatory cascade. ESLD represents a state of generalized systemic inflammation subsequently leading to endothelial dysfunction and capillary leak syndrome, potentially culminating in end-organ dysfunction.

Furthermore, patients with ESLD suffer from reduced regenerative and synthetic capacity/ability, which is reflected by the serum albumin deficiency. Serum albumin is the most important plasma protein, is produced exclusively in the liver, and houses various physiological functions: it owns immunological, immuno-modulating and anti-inflammatory properties, transport capacities, as well as detoxifying qualities. However, the most well known property of human serum albumin is maintaining the colloid osmotic pressure (COP). In the healthy individual, serum albumin is responsible for 75% up to 80% of the COP, whereas in the critically ill, the percentage proportion drops down to 17%. The COP itself accounts for the regulation and distribution of the plasma volume and is therefore essential in maintaining the vascular stability and integrity. Additionally, the endothelial glycocalyx is necessary in the context of safeguarding the endothelial function and regulating the vascular permeability. The glycocalyx covers the endothelium luminally and its core component is the heparan sulfate proteoglycan, syndecan-1. Under various clinical conditions, like ischemia/reperfusion, inflammation, sepsis, shock, major surgery, hypervolemia, degradation to the glycocalyx may happen. These pathophysiological circumstances may lead to loss of the endothelial integrity and consecutively to capillary-leak syndrome causing a loss of albumin and fluid extravasation/shifts. Various clinical and experimental studies could show that global, as well as regional ischemia and the subsequent reperfusion-phase, both lead to glycocalyx-shedding, in terms of increased syndecan-1 plasma levels. Furthermore, a previous study from our study group clearly detected increased syndecan-1 plasma levels in patients with ESLD as surrogate parameter of glycocalyx degradation mirroring the state of chronic inflammation in this patient population.

Nevertheless, a clear correlation between colloid osmotic pressure, albumin and the loss of vascular integrity in state of endothelial dysfunction has not been studied before in patients with ESLD undergoing OLT.