Publication Date:
2014-12-06
Description:
Up to 50% of preventable trauma deaths are due to truncal hemorrhage resulting in cardiovascular collapse. Lower body negative pressure (LBNP) causes central hypovolemia in humans, resulting in coagulation changes, platelet activation, and fibrinolysis. The model allows investigators to study impending hemorrhagic shock in a minimally invasive human model, but correlations to changes in clotting and lysis due to hemorrhage are not fully described. Published human data to date has not discriminated between altered coagulation due to the LBNP method versus changes attributable to incipient hemorrhagic shock. We measured multiple coagulation parameters in 16 baboons undergoing hemorrhage followed by LBNP and hypothesized that this model elicits early changes associated with acute coagulopathy due to hemorrhage. Baboons underwent incremental hemorrhage (HEM) under an ACURO-approved protocol, followed by LBNP 2-4 weeks later. Blood was sampled at baseline (T0) and after approximately 18.75% (T1), and 25% (T2) blood loss (or until presyncope), and at recovery (T3). LBNP levels were determined by matching the pulse and central venous pressures elicited by hemorrhage. Measurements included: complete blood count; blood chemistries; and coagulations tests. Parameters measured by thromboelastography (TEG) included: R-time, K-time, angle, maximum amplitude (MA), and lysis at 30 and 60 minutes (LY30, LY60). Coagulation factors were quantified over time during both experiments (STA-R Evolution, STAGO).Platelet count was measured and response to agonists (ADP, collagen, TRAP) assessed with impedance aggregometry (Multiplate, Roche Diagnostics). Markers of platelet activation were evaluated under flow cytometry (P-selectin, PAC-1, and leukocyte-platelet aggregates (CD45:CD41)). LBNP and hemorrhage caused activation of the coagulation system over time as measured by TEG R-time (HEM: T0=5.8±0.3 s; T2=4.7±0.3 s; LBNP: T0=6.5±0.3 s; T2=5.1±0.3 s; p
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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