Severe thermal injury significantly impacts upon hemostasis and is associated with classical changes to the circulating platelet count with a nadir followed by a rebound thrombocytosis at days ~3 and ~15 post-injury, respectively. To date, few studies have assessed platelet function following thermal injury as platelet tests often require large quantities of blood, are not representative of normal platelet pathophysiology, and are usually dependent on a normal platelet count. The purpose of this study was to measure platelet thrombus formation in vitro using a whole blood flow chip-based system following thermal injury and to study how platelet counts may impact upon the measurement. Adult (≥16 years) patients (N = 10) with ≥ 20% total burn surface area (TBSA) burn were recruited within 24 h of injury. Healthy controls (N = 25) were also recruited. Whole blood counts were measured using a hematology analyzer (Sysmex XN-1000). Platelet function was measured using the Total Thrombus-formation Analyzer System (T-TAS) within chips coated with tissue factor and collagen at shear rates of either 600 sec-1 (AR chips) or 1200 sec-1 (HD chips), the latter test being independent of platelet count. We confirmed the classical nadir in platelet counts following severe thermal injury at days 2, 3, 4 (p < 0.0001) and day 5 (p < 0.01) post-injury compared to healthy controls. Physiological platelet thrombus formation was significantly (p < 0.01) abnormal at day 3 post-injury using the AR chips but was related to the platelet count. However, although platelet dysfunction was not significant using HD chips, some of the results were independent of platelet count. A small number of samples, however, still gave abnormal results suggesting that there can be an underlying acquired platelet functional abnormality. Furthermore, the AR chip Area Under the Curve (AUC) was significantly lower on day 1 post-injury and negatively associated with severity of injury (TBSA, p < 0.05) and higher platelet function (AUC) positively associated with survival (p < 0.05). This study suggests that measuring platelet dysfunction within a more physiological in vitro test may have potential clinical utility. Larger studies are required to fully understand the impact of platelet dysfunction following severe thermal injury.
Keywords: Platelet count; T-TAS; platelet function; thermal injury.
What is the context? Severe Burn Injury is known to impact upon blood clotting by affecting platelet number and function.Lower numbers of platelets post-injury are associated with increased risk of poor outcomes including infection, sepsis and death.This study used a whole blood system (T-TAS) using two types of chips to measure platelet function and thrombus formation in samples from severely injured burns patientsMost platelet function tests are dependent on normal platelet counts.What is new? We confirmed the previously described fall in platelet counts from days 3–5 post-injury followed by an increase from days 10–14.Platelet function within T-TAS AR chips was shown to be abnormal at day 3 post-injury but was related to the fall in platelet count.Platelet function within T-TAS HD chips was shown to be normal but not as dependent on the platelet count. A small number of samples were still abnormal suggesting an acquired platelet abnormality.What is the impact? Platelet function can be measured independently of platelet counts using the T-TAS HD chip.Measuring platelet function using T-TAS may have clinical utility in severe burns and trauma.