Abstract
Background: Currently, whole blood is rarely used in trauma resuscitation due, in part, to the widely held belief that refrigeration will reduce the hemostatic efficacy of stored platelets. Recently, however, Pidcoke et al. (Transfusion 2013, 53:137s) showed that hemostatic function of human whole blood was well preserved when stored at 4°C for up to 21 days. The hemostatic and resuscitative efficacy of cold-stored whole blood has not been tested in a coagulopathic animal polytrauma model.
Hypothesis: We hypothesized that blood stored for 7 days at 4°C is equivalent to fresh whole blood with regard to hemostatic and coagulation function in resuscitation of severe trauma.
Method: Sprague-Dawley rats (300-400g) were anesthetized with Isoflurane. Polytrauma was induced by damaging the small intestines, the left and medial liver lobes, the right leg skeletal muscle, and by fracturing the right femur. The rats were then bled to a mean arterial pressure of 40mmHg and held there until 40% of the blood volume was removed. Hemorrhage was usually completed between 30-60 min. Resuscitation was started at 1hr and included the following groups: Lactated Ringer’s (LR), fresh whole blood (FWB) or FWB stored at 4°C for 7 days (sFWB). The resuscitation volume was 20% of blood volume and represents the approximate volume used in prehospital care of trauma patients in both civilian and military settings. The experiment was terminated at 2hrs. Blood samples were taken before (time 0) and 2hrs after trauma (1hr after resuscitation) to assess hemostatic function. Prothombin time (PT), activated partial thromboplastin time (aPTT) and fibrinogen were measured on ST-4 (Stago). Platelet aggregation was measured with Multiplate (Diapharma) after stimulation with ADP, collagen or thrombin (PAR4) and expressed as area under the curve per 1000 platelets. Clotting function was assessed using ROTEM (Tem International).
Results: Resuscitation with FWB and sFWB led to recovery of mean arterial blood pressure to levels similar to baseline (FWB 92±2.4 to 86±3, sFWB 93±3 to 91±4). Resuscitation with LR led to a significantly lower arterial pressure (96±3 to 61±3.8mmHg, p<0.05). Plasma lactate levels were significantly elevated in all groups. However, plasma lactate was lower after resuscitation with FWB and sFWB (0.52±0.06 to 1.22±0.08, and 0.5±0.05 to 1.28±0.12mM, respectively), as compared to LR (0.47±0.05 to 2.36±0.24mM). Several coagulation parameters changed significantly after resuscitation (PT, aPTT, fibrinogen, mean clotting firmness, clotting time and alpha angle). However, there was no difference in the change of any of these parameters between animals treated with FWB or sFWB. Because platelets make up most of the clot strength, we assessed the ability of agonists (ADP, thrombin agonist, collagen) to stimulate platelet aggregation. The degree of aggregation after resuscitation with all fluids was significantly decreased to stimulation with collagen (15 to 26%). However there was no significant difference in the aggregation changes between the FWB or sFWB groups. Resuscitation with any of the fluids had no effect on ADP or PAR4 stimulation of aggregation.
Conclusion: These data strongly suggest that FWB and FWB stored for 7days at 4° are equivalent for treating severe polytrauma and hemorrhage when considering recovery of arterial pressure and plasma lactate, changes in clotting function and changes in platelet aggregation as endpoints necessary for recovery of the patient. This project was funded by the US Army Medical Research and Materiel Command.
Disclosures
No relevant conflicts of interest to declare.
Reduction of Oxygen-Carrying Capacity Weakens the Effects of Increased Plasma Viscosity on Cardiac Performance in Anesthetized Hemodilution Model
