Fast Five Quiz: Organ Donation and Transplant

Beje Thomas, MD; Soon Youn Yi, MD

Disclosures

December 06, 2018

Hypothermia remains the preferred technique for organ preservation because it is simple, does not require sophisticated expensive equipment, and allows ease of transport. Hypothermia is beneficial because it slows metabolism. Organs exposed to normothermic ischemia remain viable for relatively short periods, usually less than 1 hour.

Various flush solutions are used for organ preservation to prevent cellular edema, delay cell destruction, and maximize organ function after perfusion is reestablished. The most common flush solutions include the University of Wisconsin (UW) solution and Bretschneider histidine-tryptophan-ketoglutarate (HTK) solution. Ross-Marshall citrate solutions were developed as alternatives to Collins solutions. Their electrolytic compositions are similar, except that citrate replaces phosphate and mannitol replaces glucose. The citrate acts as a buffer and chelates with magnesium to form an impermeable molecule that helps stabilize the extracellular environment. It is not commonly used in clinical practice.

Perhaps the most promising approach to the cryopreservation of whole organs lies with the process of vitrification. This is the process of taking an aqueous solution and making it into an amorphous solid. The problem with vitrifying organs is that about half of the water in an organ must be replaced with solute molecules for vitrification to occur at reasonable cooling rates. The difficulties in developing successful vitrification techniques include infusing high concentrations of vitrification solutes into the organ and removing them on thawing, preventing fracturing of the organs during cryogenic storage, and warming the organs fast enough to prevent devitrification, among other problems. Vitrification is not currently being used in clinical transplantation.

For more on the preservation of organs, read here.

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