Plasma Is the Physiologic Buffer of Tissue Plasminogen Activator-Mediated Fibrinolysis: Rationale for Plasma-First Resuscitation after Life-Threatening Hemorrhage

Abstract

Background Pre-hospital resuscitation with crystalloid exacerbates fibrinolysis, which is associated with high mortality. We hypothesize that plasma compared to crystalloid resuscitation prevents hyperfibrinolysis in a tissue plasminogen activator (tPA) rich environment via preservation of proteins essential for regulation of fibrinolysis. Study Design Healthy individuals donated blood, which was assayed using a native (non activated) thrombelastography (TEG). Whole-blood (WB) was mixed with normal saline (NS) or platelet poor plasma (PPP) at progressive dilutions. TPA was added to promote a fibrinolytic environment. In a separate experiment PPP was run through 100 KD filter and liquid remaining on top of the filter (TFP) and below the filter (BFP) was obtained. Whole blood was diluted by 50% with TFP, BPF and NS and assayed with tPA TEG challenge. TFP and BFP were assayed for protein concentration and protein composition. Results NS and PPP dilution of WB with out tPA did not affect clot lysis at 30 minutes (LY30) (NS Spearman’s Rho 0.300 p=0.186 and PPP 0.294 p=0.288). When tPA was added NS dilution of whole blood increased LY30 in a percentage dependent manner (0.844 p<0.001) but did not significantly increase with PPP dilution (0.270 p=0.202). The difference in LY30 from WB to diluted WB with PPP (mean change −1.05 95% CI −9.42 to 7.33) was similar with TFP (1.23 95%CI −5.20 to 7.66 p=0.992). However, both BPF (37.65 95%CI 24.47 to 50.82 p=0.001) and NS (47.36 95%CI 34.3–60.45 p<0.001) showed large increases in fibrinolysis compared to PPP. Conclusions Crystalloid and plasma dilution of whole blood does not increase fibrinolysis. However NS dilution of WB, increases susceptibility to tPA mediated fibrinolysis. Plasma resuscitation, simulated by plasma dilution of whole blood, attenuates increased susceptibility to tPA mediate fibrinolysis. The benefits of plasma resuscitation are mediated through preservation of plasma proteins.

Tissue injury suppresses fibrinolysis after hemorrhagic shock in nonhuman primates (rhesus macaque)

“…13 In the current study, differences in fibrinolysis were detected by FIBTEM, but not EXTEM, suggesting that platelets contribute to fibrinolysis resistance as has been previously reported. 20 Additionally, impaired platelet function has been correlated to increased sensitivity to tPA. 21 Furthermore, there is evidence that FIBTEM, and its thromboelastography (TEG) correlate, namely, functional fibrinogen, detect clot lysis sooner than the EXTEM test 22 and increased sensitivity to hyperfibrinolysis has been shown in the FIBTEM versus EXTEM test in patients undergoing liver transplant.…”

“…20 Additionally, impaired platelet function has been correlated to increased sensitivity to tPA. 21 Furthermore, there is evidence that FIBTEM, and its thromboelastography (TEG) correlate, namely, functional fibrinogen, detect clot lysis sooner than the EXTEM test 22 and increased sensitivity to hyperfibrinolysis has been shown in the FIBTEM versus EXTEM test in patients undergoing liver transplant. 23 Therefore, in the current study, it is plausible that the resistance to fibrinolysis observed was in part mediated by platelet function, and that cytochalasin-D–mediated platelet inhibition in the FIBTEM assay revealed differences in fibrinolytic activity among injury groups.…”

“…6,7,9,10,15,16,21 Previous work in rats has revealed an innate resistance to tPA-mediated fibrinolysis, which is decreased after HS but increased with tissue injury. 16 This is further supported in a swine model of a severe blast injury which produces a hypercoagulable state rather than a bleeding coagulopathy.…”

“…24 In an in vitro study in which blood from healthy donors was used, tPA increased fibrinolysis, tPA with RBC lysate augmented fibrinolysis threefold more than tPA alone, whereas platelet lysate was shown to inhibit tPA-mediated fibrinolysis. 20 Additionally, platelet microparticles, which are abundant in plasma, express surface phosphatidyl serine which has been shown to elicit procoagulant effects in vitro. However, in vivo, phosphatidyl serine only exerts procoagulant effects in the presence of procoagulant enzymes, as would be the case in the circulating blood of patients after major trauma.…”

“…In trauma patients exhibiting a hyperfibrinolytic phenotype, circulating free tPA concentrations are approximately 50 ng/mL, whereas in patients exhibiting a fibrinolysis shutdown phenotype free tPA levels were undetectable due to elevations in PAI-1 and formation of tPA-PAI-1 complex. 21 Another mechanism by which platelets have been shown to inhibit fibrinolysis is through the secretion of inorganic phosphate polymers (polyP). 28 Human platelet dense granules contain substantial amounts of polyP, which are secreted upon platelet activation and regulates blood clotting by activating the contact pathway and promoting the activation of factor V. 29 Additionally, polyP has been shown to directly modify fibrin network architecture and downregulate fibrinolysis by attenuating binding of tPA and plasminogen to fibrin; however, this effect has been shown to be effective only when polyP is incorporated into the fibrin network at the time of formation.…”