A platelet count of 40 and a central line to put in. Transfuse first, or go ahead? Right now the answer depends on which ICU you work in, and nobody actually knows which is right.

In this episode of the eCritCare Podcast, Dr Swapnil Pawar is joined by Professor Peter Watkinson (Professor of Intensive Care Medicine, University of Oxford, and Chief Investigator) and Professor Simon Stanworth (Professor of Haematology and Transfusion Medicine, University of Oxford) to discuss the T4P trial, Threshold for Platelets. T4P is a Bayesian adaptive randomised trial across five platelet transfusion thresholds, from below 10 to below 50, in critically ill patients undergoing low bleeding risk invasive procedures. It is recruiting 2,550 patients across the UK, Australia and Canada and has just passed the halfway mark.

In this conversation:

• Why platelet transfusion practice in critical care was borrowed from blood cancer patients, and why the evidence never caught up
• The UK survey that showed thresholds anywhere from under 10 to under 50 for the same procedure
• The risks side of the ledger: a biological product, transfusion reactions, unknown effects, and around £290 per unit before lab and administration costs
• Why five thresholds instead of two: drawing the threshold-response curve so the optimum does not have to be one of the arms
• Which procedures are specified (central lines, pleural aspiration, paracentesis) and which are at clinician discretion
• The adherence question, and why even the below-10 arm is being followed
• The haematology confusion: why a patient's daily platelet threshold does not stop them being in T4P
• Rotating trainees, cross-specialty equipoise, and asking clinicians to step outside a comfort zone they have practised in for years
• Operator experience, ultrasound-guided lines, and what PACER did and did not show in critical care
• What success looks like: the biggest platelet transfusion study in critical care, and a practice-changing curve

Read this episode on Substack: https://critcareedu.substack.com/p/t4p-trial-platelet-transfusion-thresholds

Trial registration: ISRCTN79371664. Funded by the NIHR Health Technology Assessment Programme (NIHR131822).