[Platelet transfusion: products, indications, dose, threshold and efficacy]

The quality of platelet concentrates had been greatly improved since the implementation of processing techniques based on the use of the buffy-coat in the years 1980. More recently, in the last 10 years, it is in the domain of safety that the greatest advances have been done, by the introduction of platelet additive solutions, on one hand, and by the progressive availability of pathogen reduction techniques, on the other hand. These developments in quality and safety of platelet components are important, as they lead to the conclusion that nowadays, apheresis platelet concentrates and pooled random donor platelet concentrates can be considered as equivalent, the only specific indication of the former being the care of HLA or HPA allo-immunized patients. This review covers the physiological basis of prophylactic and curative platelet transfusions, and the means to evaluate their efficacy. The main investigations that are necessary to perform in the event of an inefficient prophylactic transfusion are also mentioned. Platelet transfusion is an essential part of the transfusion support in case of central thrombocytopenia, and more indications in other medical and surgical situations are well defined. The vast majority of clinical situations in which platelet transfusions are indicated have been defined in the national guidelines published in 2003 by the AFSSAPS French authority, and are still fully valid today. Therefore, only some specific domains for which recent published data are questioning our present practices are discussed, such as the use of platelet concentrates in massive transfusion. Finally, three critical factors for establishing a coherent platelet transfusion strategy are developed: the transfusion trigger for prophylactic platelet transfusion, the platelet dose, and the impact of ABO compatibility between the product and the recipient.