BackgroundPlatelets (PLTs) are usually stored for up to 5 days prior to transfusion, although in some blood services the storage period is extended to 7 days. During storage, changes occur in both PLT and storage medium, which may lead to PLT activation and dysfunction. The clinical significance of these changes remains uncertain.MethodsWe performed a systematic review to assess the association between PLT storage time and clinical or transfusion outcomes in patients receiving allogeneic PLT transfusion. We searched studies published in English between January 2000 and July 2017 identified from MEDLINE, Embase, PubMed and the Cochrane Libraries.ResultsOf the 18 studies identified, five included 4719 critically ill patients (trauma, post-cardiac surgery and a heterogeneous population of critically ill patients) and 13 included 8569 haematology patients. The five studies in critically ill patients were retrospective and did not find any association between PLT storage time when PLTs were stored for up to 5 days and mortality. There was also no association between older PLTs and sepsis in the two largest studies (n = 4008 patients). Of the 13 studies in haematology patients, seven analysed prolonged storage time up to 6.5 or 7 days. Administration of fresh PLTs (less than 2 or 3 days) was associated with a significant increase in corrected count increment (CCI) compared to older PLTs in seven of the eight studies analysing this outcome. One single centre retrospective study found an increase in bleeding events in patients receiving older PLTs.ConclusionsPLT storage time does not appear to be associated with clinical outcomes, including bleeding, sepsis or mortality, in critically ill patients or haematology patients. The freshest PLTs (less than 3 days) were associated with a better CCI, although there was no impact on bleeding events, questioning the clinical significance of this association. However, there is an absence of evidence to draw definitive conclusions, especially in critically ill patients.Electronic supplementary materialThe online version of this article (10.1186/s13054-018-2114-x) contains supplementary material, which is available to authorized users.

BackgroundPlatelets are commonly transfused to critically ill patients. Reports suggest an association between platelet transfusion and infection. However, there is no large study to have determined whether platelet transfusion in critically ill patients is associated with hospital-acquired infection.MethodsWe conducted a multi-centre study using prospectively maintained databases of two large academic intensive care units (ICUs) in Australia. Characteristics of patients who received platelets in ICUs between 2008 and 2014 were compared to those of patients who did not receive platelets. Association between platelet administration and infection (bacteraemia and/or bacteriuria) was modelled using multiple logistic regression and Cox regression, with blood components as time-varying covariates. A propensity covariate adjustment was also performed to verify results.ResultsOf the 18,965 patients included, 2250 (11.9%) received platelets in ICU with a median number of 1 platelet unit (IQR 1–3) administered. Patients who received platelets were more severely ill at ICU admission (mean Acute Physiology and Chronic Health Evaluation III score 65 (SD 29) vs 52 (SD 25), p < 0.01) and had more comorbidities (31% vs 19%, p < 0.01) than patients without platelet transfusion. Invasive mechanical ventilation (87% vs 57%, p < 0.01) and renal replacement therapy (20% vs 4%, p < 0.01) were more frequently administered in patients receiving platelets than in patients without platelets. On univariate analysis, platelet transfusion was associated with hospital-acquired infection in the ICU (7.7% vs 1.4%, p < 0.01). After adjusting for confounders, including other blood components administered, patient severity, centre, year, and diagnosis category, platelet transfusions were independently associated with infection (adjusted OR 2.56 95% CI 1.98–3.31, p < 0.001). This association was also found in survival analysis with blood components as time-varying covariates (adjusted HR 1.85, 95% CI 1.41–2.41, p < 0.001) and when only bacteraemia was considered (adjusted OR 3.30, 95% CI 2.30–4.74, p <0.001). Platelet transfusions remained associated with infection after propensity covariate adjustment.ConclusionsAfter adjustment for confounders, including patient severity and other blood components, platelet transfusion was independently associated with ICU-acquired infection. Further research aiming to better understand this association and to prevent this complication is warranted.

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Massive transfusion or major haemorrhage protocols have been widely adopted in the treatment of critically bleeding patients. Following evidence that higher ratios of transfused plasma and platelets to red blood cells may offer survival benefits in military trauma patients, these ratios are now commonly incorporated into massive transfusion protocols. They more closely resemble the effects of whole blood transfusion, which in the second half of last century was largely replaced by individual blood component transfusion based on laboratory-guided indicators. However, high-quality evidence to guide transfusion support for critically bleeding patients across the range of bleeding contexts is lacking, including for both trauma and non-trauma patients. More data on major haemorrhage support and clinical outcomes are needed to inform guidelines and practice.