john mclinden biomedical engineering. a brief introduction liver failure leads to a buildup of...

John McLindenBiomedical Engineering

A Brief IntroductionLiver failure leads to a buildup of toxins in

the bloodstreamArtificial liver support systems attempt to

remove these toxins to increase survival times

Ultimately, liver can repair itself or a transplant is needed

Most early artificial liver support systems insufficient[1]

MARS and PDFMolecular Adsorption and Recycling System

(MARS) was among the first artificial liver support systems to show true promise

Used human albumin as a substrate[1]

Plasma diafiltration (PDF) is a newer, experimental system

Also uses albumin, but exchanges blood plasma and was developed to allow the passage of adiponectin (APN)[2]

MARS OverviewBlood is pumped

through an impermeable hollow fiber dialyzer with albumin containing dialysate

The molecules captured are filtered through a charcoal and anion exchange columns

Dialysate also goes through a single-pass dialyzer[3]

http://onlinelibrary.wiley.com.uri.idm.oclc.org/doi/10.1053/jhep.2002.36130/pdf

PDF OverviewUses an

anticoagulant, dialysate, replacement fluid, and a human plasma/albumin mixture

Also uses a membrane that allows the passage of APN, which is believed to have anti-inflammatory properties[2]

http://onlinelibrary.wiley.com.uri.idm.oclc.org/doi/10.1111/1744-9987.12344/pdf

MARS ResultsSome studies reported increases in 30-day

survivability compared to standard medical procedure[4]

One reported that MARS patients experienced an 8.3% mortality rate versus patients receiving standard medical treatment, who experienced a 50% mortality rate[3]

MARS Results Cont.However, recent reviews of multiple MARS

studies claim that the system does not have a significant effect on 30-day survivability

It is possible that the data were skewed because sepsis may have begun before the treatments were administered, which is a significant complication.[4]

PDF ResultsPDF saw a

significant increase in median APN levels (11.64μg/mL before PDF to 14.52 μg/mL after PDF)

For comparison, plasma exchange (PE) patients experienced a drop in median APN levels (11.53μg/mL before PE to 7.22μg/mL after)[2]

http://onlinelibrary.wiley.com.uri.idm.oclc.org/doi/10.1111/1744-9987.12344/pdf

PDF Results Cont.However, increased pore size of the

membrane could have allowed inflammatory cytokines through as well

These could mitigate the beneficial effects of APN[2]

ConclusionMARS has been tested for many years, with

mixed resultsFurther testing is required to understand the

conditions under which MARS would be most effective[4]

PDF was able to significantly increase APN levels, but requires more research to determine if it will ever become common practice[2]

References[1] Maiwall, R. et. al. Liver dialysis in acute-on-

chronic liver failure: current and future perspectives. Hepatology International, 8(2): 505-13, 2014.

[2] Yamamoto, H. et. al. Plasma adiponectin levels in acute liver failure patients treated with plasma filtration with dialysis and plasma exchange. Therapeutic Apheresis and Dialysis, 19(4): 349-353, 2015.

[3] Hassanein T. et. al. Albumin dialysis in cirrhosis with superimposed acute liver injury: a prospective, controlled study. Hepatology, 36 (4): 949-58 2002.

[4] Wauters, J. & Wilmer, A. Albumin dialysis: current practice and future options. Liver International, 31 (s3): 9-12 2011.

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