Cryopreserved versus liquid platelets for surgical bleeding in cardiac surgery

Cryopreserved versus liquid platelets for surgical bleeding in cardiac surgery


CLIP-II: The cryopreserved vs liquid platelets trial for surgical bleeding

This is a definitive trial to determine if cryopreserved platelets are as safe and effective as liquid-stored platelets in high-risk adult cardiac surgery patients.

Principal investigator

Professor Michael Reade FANZCA


The protocol has ethics approval and all study procedures are in place. Engagement with 12 selected study sites has progressed with platelet manufacture which allowed for the first patient to be recruited in August 2021. Currently nine sites are actively recruiting: the Royal Prince Alfred Hospital, Prince Charles Hospital, Townsville University Hospital, the Austin Hospital, Gold Coast University Hospital, St. Vincent’s Hospital Melbourne, Westmead Hospital, the Alfred Hospital and the Royal Melbourne Hospital. To date, 124 participants have been randomised with 75 participants receiving study platelets.

In New Zealand, an investigative team led by Dr Shay McGuinness and Associate Professor Rachael Parke, has received funding from the NZ Health Research Council (HRC) to run a parallel protocol using cryopreserved platelets manufactured by a slightly different technique.


Platelets are stored at 22°C to prolong circulating time after transfusion. This risks bacterial growth, limiting shelf-life to five days. Freezing, using dimethylsuphoxide (DMSO) as a cryoprotectant, extends shelf-life to two years. However, despite development by the US Navy in the 1970s, only one clinical trial, in which only 24 patients received cryopreserved platelets, has been published. This small study found cryopreserved platelets were safe and more effective than liquid-stored platelets. Funded by an ANZCA Academic Enhancement Grant, the CLIP investigators (a collaboration of the Australian Defence Force, the Australian Red Cross Blood Service led by Dr Denese Marks, and civilian hospital clinicians around Australia) have completed the CLIP-I pilot trial, demonstrating the feasibility and safety of a protocol comparing frozen and liquid platelets in cardiac surgery patients. The CLIP investigators secured a $A1.85 million NHMRC grant to run a definitive trial in 10 to 12 Australian hospitals. If cryopreserved platelets are as safe and effective as hypothesised, the study will change the way platelets are stored worldwide, and make platelet transfusions possible in the many small hospitals that currently have no platelet blood bank. Study design: Randomised, double-blind non-inferiority phase III clinical trial in high-risk adult cardiac surgery patients.

Study size
808 patients randomised to achieve 202 patients transfused platelets (101 in each group). Primary outcome: Volume of post-surgical bleeding in the first 24 hours from the time of ICU admission.

Secondary outcomes
Transfusion and fluid resuscitation requirement; Bleeding Academic Research Consortium composite bleeding outcome; adverse effects (specifically: DMSO toxicity; infection; venous thromboembolism; arterial occlusion; need for surgical intervention; and acute respiratory distress syndrome); total estimated healthcare cost.

Study duration 
Four years.


The Australian National Health and Medical Research Council


The CLIP-II study is endorsed by the Australian and New Zealand Intensive Care Society Clinical Trials Group (ANZICS-CTG), the ANZCA Clinical Trials Network, and the Australian and New Zealand Society of Cardiac and Thoracic Surgeons.

Trial registration Identifier: NCT03991481

Per patient payment

$A100 per consented participant and $A900 per transfused participant

Participating hospitals

Australian Hospitals
Alfred Hospital
Austin Health
Gold Coast University Hospital
Royal Prince Alfred 
St Vincents Hospital, Melbourne
The Prince Charles Hospital 
Townsville University Hospital 
Westmead Hospital
New Zealand Hospitals
Auckland City Hospital CVICU
Christchurch Hospital
Dunedin Hospital
Waikato Hospital
Wellington Hospital

How to get involved

For further information about this study, please contact the ANZIC-RC CLIP-II Project Manager, Belinda Howe by email.

Last updated 15:51 6.03.2023