Transfusion medicine

Evidence building for use of frozen platelets

There is new evidence on the safety of frozen versus fresh platelets – opening up the potential opportunity to use the extended shelf life product in routine clinical care.

Professor Michael Reade, Defence Professor of Military Medicine and Surgery at the University of Queensland, told the ISTH Congress that fresh platelets were typically not available in smaller and regional hospitals because they only lasted for 5-7 days.

Cryopreservation of platelets extends their shelf life to about four years.

He said frozen platelets had already been used in military field hospitals but not in civilian settings outside clinical trials.

However a pilot randomised controlled trial, just published in Transfusion, had shown use of the frozen platelets to be feasible and without any adverse outcomes compared to conventional liquid-stored platelets.

The 121 adult cardiac surgery patients in the trial met TRUST criteria indicating they were at high risk for red blood cell transfusion.

Patients were randomised to received up to three units of either fresh or frozen platelets, if clinically required, either during their procedure or during their post operative stay in ICU.

Of the 41 patients who required platelets, most received their first transfusion during their surgery.

The study found no differences in intra- or postoperative blood loss between the two groups. Postoperative aspirin and heparin were introduced on day 2 in both groups.

However there were some differences in transfusion requirements with patients receiving the frozen platelets using significantly more fresh frozen plasma (18 v 5 units FFP) and more platelets than the other patients (2 v 1 units).

The study authors suggested a number of explanations for the excess use of fresh frozen plasma including the reconstitution of frozen platelets in FFP leading to charting errors.

Safety outcomes including maximum temperature, PaO2/FiO2 ratio, hospital length of stay, infections, DVT, AMI and mortality were similar in both groups.

Professor Reade said the data was not yet enough for regulatory approval of frozen platelets in civilian use, although they were used in the military when there was no alternative.

A second Cryopreserved vs Liquid Platelet (CLIP) study is underway. It will include a cost-effectiveness analysis to determine which types of hospitals might benefit from having access to frozen platelets.

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