Comparison of fresh frozen plasma vs. coagulation factor concentrates for reconstitution of blood: An in vitro study.

BACKGROUND: Many trauma centres have adopted the administration of fixed ratios of packed red blood cells (PRBCs), platelet concentrates and fresh frozen plasma (FFP) for bleeding patients. However, the haemostatic efficacy of this concept is not well proven. OBJECTIVE: Our objective was to characterise the haemostatic profile of different ratios (2 : 1 : 1, 1 : 1 : 1 and 1 : 1 : 2) of PRBCs, platelet concentrates and FFP in comparison with coagulation factor concentrates (fibrinogen and/or prothrombin complex concentrate). DESIGN: An in vitro study. SETTING: Research laboratories of the department of transfusion medicine, Linz, Austria. MATERIALS: Whole blood donations from a total of 20 male volunteers. INTERVENTION: Reconstitution of blood at different ratios of PRBCs, platelet concentrates and FFP or coagulation factor concentrates. MAIN OUTCOME MEASURES: Cell count, conventional and thromboelastometric coagulation parameters, single coagulation factor activities as well as endogenous thrombin potential. RESULTS: Fibrinogen levels and haematocrit were lower in the FFP group at any ratio compared with the concentrate-based groups (P < 0.0001). Reconstitution of blood with FFP at different ratios resulted in haematocrit or fibrinogen levels that were borderline with regard to recommended substitution triggers (haematocrit 41 ±â€Š2% and fibrinogen 1.5 ±â€Š0.3 g l at the 2 : 1 : 1 ratio vs. 21 ±â€Š1% and 2.1 ±â€Š0.4 g l respectively at the 1 : 1 : 2 ratio). Compared with FFP at any ratio, maximum clot firmness showed higher values in the groups using fibrinogen concentrate (P < 0.0001), whereas endogenous thrombin potential revealed higher values in the groups using prothrombin complex concentrate (P < 0.0001). CONCLUSION: Use of coagulation factor concentrates for the reconstitution of blood allows for delivery of a higher haematocrit and a higher fibrinogen content compared with FFP. However, prothrombin complex concentrate might result in an unnecessary excess of thrombin generation. Clinical studies are warranted to further investigate these in vitro findings.

Concentrated lyophilized plasma used for reconstitution of whole blood leads to higher coagulation factor activity but unchanged thrombin potential compared with fresh-frozen plasma.

BACKGROUND: During massive hemorrhage, it is recommended to transfuse red blood cells, platelet concentrate, and fresh-frozen plasma in a ratio close to 1:1:1. To avoid the thawing process of fresh frozen plasma, lyophilized plasma (LP) is increasingly used. Evidence is limited on the activity of coagulation factors in reconstituted blood using LP and concentrated LP versions. STUDY DESIGN AND METHODS: Whole blood from ten healthy volunteers was separated into red blood cell, fresh frozen plasma, and platelet concentrate units. Aliquots of red blood cells and plasma concentrate were mixed with either fresh frozen plasma (200 mL) or LP at reconstitution ratios of 2:1:1, 1:1:1, and 1:1:2. LP was used either at the recommended standard volume of 200 mL (LP200) or was more concentrated at volumes of 100 and 50 mL (LP100 and LP50, respectively). The hemostatic capacity of each reconstituted whole blood sample was tested with blood cell counts, standard coagulation tests, factor activity, thrombin generation, and viscoelastic assays. RESULTS: Hematocrit, platelet counts, and fibrinogen levels of the three ratios were similar between FFP200 and LP200 units but were lower compared with the corresponding ratios in LP100 and LP50 units. The activity of procoagulant and anticoagulant factors increased linearly with the increasing plasmatic fraction and, at 1:1:2 ratio, was significantly higher in LP50 units compared with FFP200 and LP200 units. Thrombin generation was similar throughout the four plasma groups at any ratio. CONCLUSIONS: Decreasing the dilution volume of LP facilitates reaching higher hematocrit and coagulation protein levels without a relevant increase in thrombin generation. This is due to preserved balance between procoagulant and anticoagulant factors in the concentrated LP preparations.

Preferential effects of low volume versus high volume replacement with crystalloid fluid in a hemorrhagic shock model in pigs.

BACKGROUND: Fluid resuscitation is a core stone of hemorrhagic shock therapy, and crystalloid fluids seem to be associated with lower mortality compared to colloids. However, as redistribution starts within minutes, it has been suggested to replace blood loss with a minimum of a three-fold amount of crystalloids. The hypothesis was that in comparison to high volume (HV), a lower crystalloid volume (LV) achieves a favorable coagulation profile and exerts sufficient haemodynamics in the acute phase of resuscitation. METHODS: In 24 anaesthetized pigs, controlled arterial blood loss of 50 % of the estimated blood volume was either (n = 12) replaced with a LV (one-fold) or a HV (three-fold) volume of a balanced, acetated crystalloid solution at room temperature. Hemodynamic parameters, dilution effects and coagulation profile by standard coagulation tests and thromboelastometry at baseline and after resuscitation were determined in both groups. RESULTS: LV resuscitation increased MAP significantly less compared to the HV, 61 ± 7 vs. 82 ± 14 mmHg (p < 0.001) respectively, with no difference between lactate and base excess between groups. Haematocrit after fluid replacement was 0.20 vs. 0.16 (LV vs. HV, p < 0.001), suggesting a grade of blood dilution of 32 vs. 42 % (p < 0.001) compared to baseline values. Compared to LV, HV resulted in decreased core temperature (37.5 ± 0.2 vs. 36.0 ± 0.6 °C, p < 0.001), lower platelet count (318 ± 77 vs. 231 ± 53 K/µL, p < 0.01) and lower plasma fibrinogen levels (205 ± 19 vs. 168 ± 24 mg/dL, p < 0.001). Thromboelastometric measurements showed a significant impairment on viscoelastic clot properties following HV group. While prothrombin time index decreased significantly more in the HV group, activated partial thromboplastin time did not differ between both groups. HV did not result in hyperchloraemic acidosis. DISCUSSION: Coagulation parameters represented by plasma fibrinogen and ROTEM parameters were also less impaired with LV. With regrad to hematocrit, 60 % of LV remained intracascular , while in HV only 30 % remained in circulation within the first hour of administration. In the acute setting of 50 % controlled blood loss, a one fold LV crystalloid replacement strategy is sufficient to adequately raise blood pressure up to a mean arterial pressure >50 mm Hg. The concept of damage control resuscitation (DCR) with permissive hypotension may be better met by using LV as compared to a three fold HV resuscitation strategy. CONCLUSION: High volume administration of an acetated balanced crystalloid does not lead to hyperchloraemic acidosis, but may negatively influence clinical parameters, such as higher blood pressure, lower body temperature and impaired coagulation parameters, which could potentially increase bleeding after trauma. Replacement of acute blood loss with just an equal amount of an acetated balanced crystalloid appears to be the preferential treatment strategy in the acute phase after controlled bleeding.

Estimation of plasma fibrinogen levels based on hemoglobin, base excess and Injury Severity Score upon emergency room admission.

INTRODUCTION: Fibrinogen plays a key role in hemostasis and is the first coagulation factor to reach critical levels in massively bleeding trauma patients. Consequently, rapid estimation of plasma fibrinogen (FIB) is essential upon emergency room (ER) admission, but is not part of routine coagulation monitoring in many centers. We investigated the predictive ability of the laboratory parameters hemoglobin (Hb) and base excess (BE) upon admission, as well as the Injury Severity Score (ISS), to estimate FIB in major trauma patients. METHODS: In this retrospective study, major trauma patients (ISS ≥16) with documented FIB analysis upon ER admission were eligible for inclusion. FIB was correlated with Hb, BE and ISS, alone and in combination, using regression analysis. RESULTS: A total of 675 patients were enrolled (median ISS 27). FIB upon admission correlated strongly with Hb, BE and ISS. Multiple regression analysis showed that Hb and BE together predicted FIB (adjusted R2 = 0.46; loge(FIB) = 3.567 + 0.223.Hb - 0.007.Hb2 + 0.044.BE), and predictive strength increased when ISS was included (adjusted R2 = 0.51; loge(FIB) = 4.188 + 0.243.Hb - 0.008.Hb2 + 0.036.BE - 0.031.ISS + 0.0003.ISS2). Of all major trauma patients admitted with Hb <12 g/dL, 74% had low (<200 mg/dL) FIB and 54% had critical (<150 mg/dL) FIB. Of patients admitted with Hb <10 g/dL, 89% had low FIB and 73% had critical FIB. These values increased to 93% and 89%, respectively, among patients with an admission Hb <8 g/dL. Sixty-six percent of patients with only a weakly negative BE (<-2 mmol/L) showed low FIB. Of patients with BE <-6 mmol/L upon admission, 81% had low FIB and 63% had critical FIB. The corresponding values for BE <-10 mmol/L were 89% and 78%, respectively. CONCLUSIONS: Upon ER admission, FIB of major trauma patients shows strong correlation with rapidly obtainable, routine laboratory parameters such as Hb and BE. These two parameters might provide an insightful and rapid tool to identify major trauma patients at risk of acquired hypofibrinogenemia. Early calculation of ISS could further increase the ability to predict FIB in these patients. We propose that FIB can be estimated during the initial phase of trauma care based on bedside tests.

Meta-analysis of randomized trials of effect of milrinone on mortality in cardiac surgery: an update.

OBJECTIVE: The long-term use of milrinone is associated with increased mortality in chronic heart failure. A recent meta-analysis suggested that it might increase mortality in patients undergoing cardiac surgery. The authors conducted an updated meta-analysis of randomized trials in patients undergoing cardiac surgery to determine if milrinone impacted survival. DESIGN: A meta-analysis. SETTING: Hospitals. PARTICIPANTS: One thousand thirty-seven patients from 20 randomized trials. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Biomed, Central, PubMed, EMBASE, the Cochrane central register of clinical trials, and conference proceedings were searched for randomized trials that compared milrinone versus placebo or any other control in adult and pediatric patients undergoing cardiac surgery. Authors of trials that did not include mortality data were contacted. Only trials for which mortality data were available were included. Overall analysis showed no difference in mortality between patients receiving milrinone versus control (12/554 [2.2%] in the milrinone group v 10/483 [2.1%] in the control arm; relative risk [RR] = 1.15; 95% confidence interval [CI], 0.55-2.43; p = 0.7) or in analysis restricted to adults (11/364 [3%] in the milrinone group v 9/371 [2.4%] in the control arm; RR = 1.17; 95% CI, 0.54-2.53; p = 0.7). Sensitivity analyses in trials with a low risk of bias showed a trend toward an increase in mortality with milrinone (8/153 [5.2%] in the milrinone arm v 2/152 [1.3%] in the control arm; RR = 2.71; 95% CI, 0.82-9; p for effect = 0.10). CONCLUSIONS: Despite theoretic concerns for increased mortality with intravenous milrinone in patients undergoing cardiac surgery, the authors were unable to confirm an adverse effect on survival. However, sensitivity analysis of high-quality trials showed a trend toward increased mortality with milrinone.

Reducing mortality in acute kidney injury patients: systematic review and international web-based survey.

OBJECTIVE: To identify all interventions that increase or reduce mortality in patients with acute kidney injury (AKI) and to establish the agreement between stated beliefs and actual practice in this setting. DESIGN AND SETTING: Systematic literature review and international web-based survey. PARTICIPANTS: More than 300 physicians from 62 countries. INTERVENTIONS: Several databases, including MEDLINE/PubMed, were searched with no time limits (updated February 14, 2012) to identify all the drugs/techniques/strategies that fulfilled all the following criteria: (a) published in a peer-reviewed journal, (b) dealing with critically ill adult patients with or at risk for acute kidney injury, and (c) reporting a statistically significant reduction or increase in mortality. MEASUREMENTS AND MAIN RESULTS: Of the 18 identified interventions, 15 reduced mortality and 3 increased mortality. Perioperative hemodynamic optimization, albumin in cirrhotic patients, terlipressin for hepatorenal syndrome type 1, human immunoglobulin, peri-angiography hemofiltration, fenoldopam, plasma exchange in multiple-myeloma-associated AKI, increased intensity of renal replacement therapy (RRT), CVVH in severely burned patients, vasopressin in septic shock, furosemide by continuous infusion, citrate in continuous RRT, N-acetylcysteine, continuous and early RRT might reduce mortality in critically ill patients with or at risk for AKI; positive fluid balance, hydroxyethyl starch and loop diuretics might increase mortality in critically ill patients with or at risk for AKI. Web-based opinion differed from consensus opinion for 30% of interventions and self-reported practice for 3 interventions. CONCLUSION: The authors identified all interventions with at least 1 study suggesting a significant effect on mortality in patients with or at risk of AKI and found that there is discordance between participant stated beliefs and actual practice regarding these topics.

Milrinone and mortality in adult cardiac surgery: a meta-analysis.

OBJECTIVE: The authors conducted a review of randomized studies to show whether there are any increases or decreases in survival when using milrinone in patients undergoing cardiac surgery. DESIGN: A meta-analysis. SETTING: Hospitals. PARTICIPANTS: Five hundred eighteen patients from 13 randomized trials. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: BioMedCentral, PubMed EMBASE, the Cochrane central register of clinical trials, and conference proceedings were searched for randomized trials that compared milrinone versus placebo or any other control in the setting of cardiac surgery that reported data on mortality. Overall analysis showed that milrinone increased perioperative mortality (13/249 [5.2%] in the milrinone group v 6/269 [2.2%] in the control arm, odds ratio [OR] = 2.67 [1.05-6.79], p for effect = 0.04, p for heterogeneity = 0.23, I(2) = 25% with 518 patients and 13 studies included). Subanalyses confirmed increased mortality with milrinone (9/84 deaths [10.7%] v 3/105 deaths [2.9%] with other drugs as control, OR = 4.19 [1.27-13.84], p = 0.02) with 189 patients and 5 studies included) but did not confirm a difference in mortality (4/165 [2.4%] in the milrinone group v 3/164 [1.8%] with placebo or nothing as control, OR = 1.27 [0.28-5.84], p = 0.76 with 329 patients and 8 studies included). CONCLUSIONS: This analysis suggests that milrinone might increase mortality in adult patients undergoing cardiac surgery. The effect was seen only in patients having an active inotropic drug for comparison and not in the placebo subgroup. Therefore, the question remains whether milrinone increased mortality or if the control inotropic drugs were more protective.

Randomized evidence for reduction of perioperative mortality.

OBJECTIVE: With more than 220 million major surgical procedures performed annually, perioperative interventions leading to even minor mortality reductions would save thousands of lives per year. This international consensus conference aimed to identify all nonsurgical interventions that increase or reduce perioperative mortality as suggested by randomized evidence. DESIGN AND SETTING: A web-based international consensus conference. PARTICIPANTS: More than 1,000 physicians from 77 countries participated in this web-based consensus conference. INTERVENTIONS: Systematic literature searches (MEDLINE/PubMed, June 8, 2011) were used to identify the papers with a statistically significant effect on mortality together with contacts with experts. Interventions were considered eligible for evaluation if they (1) were published in peer-reviewed journals, (2) dealt with a nonsurgical intervention (drug/technique/strategy) in adult patients undergoing surgery, and (3) provided a statistically significant mortality increase or reduction as suggested by a randomized trial or meta-analysis of randomized trials. MEASUREMENTS AND MAIN RESULTS: Fourteen interventions that might change perioperative mortality in adult surgery were identified. Interventions that might reduce mortality include chlorhexidine oral rinse, clonidine, insulin, intra-aortic balloon pump, leukodepletion, levosimendan, neuraxial anesthesia, noninvasive respiratory support, hemodynamic optimization, oxygen, selective decontamination of the digestive tract, and volatile anesthetics. In contrast, aprotinin and extended-release metoprolol might increase mortality. CONCLUSIONS: Future research and health care funding should be directed toward studying and evaluating these interventions.

Factor XIII Measurement and Substitution in Trauma Patients after Admission to an Intensive Care Unit.

Trauma patients admitted to an intensive care unit (ICU) may potentially experience a deficiency of coagulation factor thirteen (FXIII). In this retrospective cohort study conducted at a specialized trauma center, ICU patients were studied to determine the dependency of FXIII activity levels on clinical course and substitution with blood and coagulation products. A total of 189 patients with a median injury severity score (ISS) of 25 (16−36, IQR) were included. Abbreviated injury scores for extremities (r = −0.38, p < 0.0001) but not ISS (r = −0.03, p = 0.45) showed a negative correlation with initial FXIII levels. Patients receiving FXIII concentrate presented with a median initial FXIII level of 54 (48−59)% vs. 88 (74−108)%, p < 0.0001 versus controls; they had fewer ICU-free days: 17 (0−22) vs. 22 (16−24), p = 0.0001; and received higher amounts of red blood cell units: 5 (2−9) vs. 4 (1−7), p < 0.03 before, and 4 (2−7) vs. 1 (0−2), p < 0.0001 after FXIII substitution. Matched-pair analyses based on similar initial FXIII levels did not reveal better outcome endpoints in the FXIII-substituted group. The study showed that a low initial FXIII level correlated with the clinical course in this trauma cohort, but a substitution of FXIII did not improve endpoints within the range of the studied FXIII levels. Future prospective studies should investigate the utility of FXIII measurement and lower threshold values of FXIII, which trigger substitution in trauma patients.

Recombinant activated factor VII increases stroke in cardiac surgery: a meta-analysis.

OBJECTIVES: Recombinant activated factor VII (rFVIIa) is used in various surgical procedures to reduce the incidence of major blood loss and the need for re-exploration. Few clinical trials have investigated rFVIIa in cardiac surgery. The authors performed a meta-analysis focusing on the rate of stroke and surgical re-exploration. DESIGN: Meta-analysis. SETTING: Hospitals. PARTICIPANTS: A total of 470 patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Four investigators independently searched PubMed and conference proceedings including backward snowballing (ie, scanning of reference of retrieved articles and pertinent reviews) and contacted international experts. A total of 470 patients (254 receiving rFVIIa and 216 controls) from 6 clinical trials (2 randomized, 3 propensity matched, and 1 case matched) were included in the analysis. The use of rFVIIa was associated with an increased rate of stroke (12/254 [4.7%] in the rFVIIa group v 2/216 [0.9%] in the control arm, odds ratio [OR] = 3.69 [1.1-12.38], p = 0.03) with a nonsignificant reduction in rate of surgical re-exploration (13% v 42% [OR = 0.27 (0.04-1.9), p = 0.19]). The authors observed a trend toward an increase of overall perioperative thromboembolic events (19/254 [7.5%] in the rFVIIa group v 10/216 [5.6%] in the control arm [OR = 1.84 (0.82-4.09), p = 0.14]). No difference in the rate of death was observed. CONCLUSIONS: The administration of rFVIIa in cardiac surgery patients could result in a significant increase of stroke with a trend toward a reduction of the need for surgical re-exploration. The authors do not recommend routine use in cardiac surgery patients. rFVIIa may be considered with caution in patients with refractory life-threatening bleeding.

Effect of Coagulation Factor Concentrates on Markers of Endothelial Cell Damage in Experimental Hemorrhagic Shock.

BACKGROUND: Plasma-based resuscitation showed protective effects on the endothelial glycocalyx compared with crystalloid resuscitation. There is paucity of data regarding the effect of coagulation factor concentrates (CFC) on the glycocalyx in hemorrhagic shock (HS). We hypothesized that colloid-based resuscitation supplemented with CFCs offers a therapeutic value to treat endothelial damage following HS. METHODS: Eighty-four rats were subjected to pressure-controlled (mean arterial pressure (MAP) 30-35 mm Hg) and lab-guided (targeted cutoff: lactate >2.2. mmol/L and base deficit > 5.5 mmol/L) HS. Animals were resuscitated with fresh frozen plasma (FFP), human albumin (HA) or Ringer's lactate (RL) and RL or HA supplemented with fibrinogen concentrate (FC) or prothrombin complex concentrate (PCC). Serum epinephrine and the following markers of endothelial damage were assessed at baseline and at the end-of-observation (120 min after shock was terminated): syndecan-1, heparan sulfate, and soluble vascular endothelial growth factor receptor 1 (sVEGFR 1). RESULTS: Resuscitation with FFP had no effect on sVEGFR1 compared with crystalloid-based resuscitation (FFP: 19.3 ng/mL vs. RL: 15.9 ng/mL; RL+FC: 19.7 ng/mL; RL+PCC: 18.9 ng/mL; n.s.). At the end-of-observation, syndecan-1 was similar among all groups. Interestingly, HA+FC treated animals displayed the highest syndecan-1 concentration (12.07 ng/mL). Resuscitation with FFP restored heparan sulfate back to baseline (baseline: 36 ng/mL vs. end-of-observation: 36 ng/mL). CONCLUSION: The current study revealed that plasma-based resuscitation normalized circulating heparan sulfate but not syndecan-1. Co-administration of CFC had no further effect on glycocalyx shedding suggesting a lack of its therapeutic potential. LEVEL OF EVIDENCE: VExperimental in vivo study.

The impact of direct oral anticoagulants in traumatic brain injury patients greater than 60-years-old.

BACKGROUND: Traumatic brain injury (TBI) is the leading cause of death among trauma patients. Patients under antithrombotic therapy (ATT) carry an increased risk for intracranial haematoma (ICH) formation. There is a paucity of data about the role of direct oral anticoagulants (DOACs) among TBI patients. METHODS: In this retrospective study, we investigated all TBI patients ≥60-years-old who were admitted to the intensive care unit (ICU) from January 2014 until May 2017. Patients were grouped into those receiving vitamin K antagonists (VKA), platelet inhibitors (PI), DOACs and no antithrombotic therapy (no-ATT). RESULTS: One-hundred-eighty-six, predominantly male (52.7%) TBI patients with a median age of 79 years (range: 70-85 years) were enrolled in the study. Glasgow Coma Scale and S-100ß were not different among the groups. Patients on VKA and DOACs had a higher Charlson Comorbidity Index compared to the PI group and no-ATT group (p = 0.0021). The VKA group received reversal agents significantly more often than the other groups (p < 0.0001). Haematoma progression in the follow-up cranial computed tomography (CCT) was lowest in the DOAC group. The number of CCT and surgical interventions were low with no differences between the groups. No relevant differences in ICU and hospital length of stay were observed. Mortality in the VKA group was significantly higher compared to DOAC, PI and no-ATT group (p = 0.047). DISCUSSION: Data from huge registry studies displayed higher efficacy and lower fatal bleeding rates for DOACs compared to VKAs. The current study revealed comparable results. Despite the fact that TBI patients on VKAs received reversal agents more often than patients on DOACs (84.4% vs. 24.2%, p < 0.001), mortality rate was significantly higher in the VKA group (p = 0.047). CONCLUSION: In patients ≥60 years suffering from TBI, anticoagulation with DOACs appears to be safer than with VKA. Anti-thrombotic therapy with VKA resulted in a worse outcome compared to DOACs and PI. Further studies are warranted to confirm this finding.

Experimental Models of Endotheliopathy: Impact of Shock Severity.

BACKGROUND: Hemorrhagic shock (HS) followed by resuscitation is often associated with sympathoadrenal activation (SAA) and endothelial damage (ED). OBJECTIVE: We aimed to evaluate the impact of HS alone on the magnitude of SAA and consecutive ED, and to characterize potential targets for a standardized and reproducible model of HS-induced endotheliopathy in rats. METHODS: Rats were subjected either to a volume-controlled HS (40% of total blood volume: v-HS group) or to a laboratory-guided HS (l-HS) targeting base deficit (BD) more than 5.5 mmol/L and/or lactate more than 2.2 mmol/L using a pressure-controlled volume loss. RESULTS: At the end of shock, mean arterial pressure was significantly higher in the v-HS than the l-HS group (36 ±â€Š5.6 vs. 30 ±â€Š3.0 mmHg; P < 0.01). Base deficit and lactate were higher in l-HS than the v-HS group (BD: 9.5 ±â€Š2.5 vs. 3.0 ±â€Š1.0 mmol/L; P < 0.001; lactate: 4.1 ±â€Š1.3 vs. 1.6 ±â€Š0.6 mmol/L; P < 0.001). sVEGFR-1 and syndecan-1 were approximately 50% higher in the l-HS than the v-HS group (% changes vs. baseline: 160 ±â€Š10 vs. 116 ±â€Š36; P < 0.01; 170 ±â€Š37 vs. 113 ±â€Š27; P < 0.001). Adrenaline was 2-fold higher in l-HS than the v-HS group (1964 ±â€Š961% vs. 855 ±â€Š451%; P < 0.02, respectively). Moreover, linear regression analysis revealed an independent association of shock severity BD with syndecan-1 (rho = 0.55, P = 0.0005), sVEGFR1 (rho = 0.25, P < 0.05), and adrenaline (rho = 0.31, P = 0.021). CONCLUSIONS: Our findings indicate that ED has already occurred during HS without reperfusion; intensity is strongly related to the severity of HS and consecutive SAA; and severity may appropriately be targeted and standardized in a HS model controlled by biological endpoints such as BD and/or lactate.

Potential role of platelet-leukocyte aggregation in trauma-induced coagulopathy: Ex vivo findings.

BACKGROUND: Platelet dysfunction has been identified as an important contributor of trauma-induced coagulopathy, but the underlying mechanism still remains to be elucidated. Trauma-associated proinflammatory stimuli strongly activate leukocytes, which in turn bind activated platelets. Therefore, we investigated the role of platelet-leukocyte aggregation (PLA) as a potential feature of trauma-induced platelet dysfunction. METHODS: Whole blood from 10 healthy donors was exposed to selective and collective platelet and leukocyte agonists in order to simulate differential states of activation. PLA formation and CD11b expression as a measure of leukocyte activation were determined by flow cytometry. Platelet-mediated hemostatic function was measured by thromboelastometry (ROTEM) and impedance aggregometry (Multiplate). RESULTS: Activation of platelets and leukocytes was associated with diminished platelet-mediated hemostatic potential. Aggregation of platelets with monocytes rather than granulocytes resulted in a reduction of hemostatic function, as indicated by an impaired responsiveness in platelet aggregometry and a reduction of thromboelastometric maximum clot firmness. This finding was irrespective of CD11b expression and was not paralleled by a reduction of measurable platelet counts. CONCLUSION: PLA formation occurs primarily between monocytes and activated platelets and is associated with impaired platelet-mediated hemostatic function. PLA formation was not paralleled by a reduction in platelet complete blood counts.

Fibrinogen levels in trauma patients during the first seven days after fibrinogen concentrate therapy: a retrospective study.

BACKGROUND: Fibrinogen concentrate (FC) is increasingly used as first line therapy in bleeding trauma patients. It remains unproven whether FC application increases post-traumatic plasma fibrinogen concentration (FIB) in injured patients, possibly constituting a prothrombotic risk. Thus, we investigated the evolution of FIB following trauma in patients with or without FC therapy. METHODS: At the AUVA Trauma Centre, Salzburg, we performed a retrospective study of patients admitted to the emergency room and whose FIB levels were documented thereafter up to day 7 post-trauma. Patients were categorized into those with (treatment group) or without (control group) FC therapy during the first 24 h after hospital admission. A subgroup analysis was carried out to investigate the influence of the amount of FC given. RESULTS: The study enrolled 435 patients: treatment group, n = 242 (56 %); control group, n = 193 (44%), with median Injury Severity Score of 34 vs. 22 (P < 0.001) and massive transfusion rate of 18.4% vs. 0.2% (P < 0.001). In the treatment group (median FC dose 6 g), FIB was lower on admission and up to day 2 compared with the control group. In patients receiving high (≥10 g) doses of FC, FIB was lower up to day 5 as compared to controls. At other timepoints, FIB did not differ significantly between the groups. In the treatment vs. the control group, other coagulation parameters such as prothrombin time index and platelet count were consistently lower, while activated partial thromboplastin time was consistently prolonged at most timepoints. Inflammatory parameters such as C-reactive protein, interleukin-6 and procalcitonin were generally lower in controls. DISCUSSION: The rise of FIB levels from day 2 onwards in our study can be attributed to an upregulated fibrinogen synthesis in the liver, occurring in both study groups as part of the acute phase response after tissue injury. CONCLUSIONS: The treatment of severe trauma patients with FC during bleeding management in the first 24 h after hospital admission does not lead to higher FIB levels post-trauma beyond that occurring naturally due to the acute phase response.

Platelet function in baboons and humans - A comparative study of whole blood using impedance platelet aggregometry (Multiplate®).

BACKGROUND: Platelets play a pivotal role in coagulation, inflammation and wound healing. Suitable animal models that have the potential to mimic human platelet function are limited. The objective of the current study was to compare platelet aggregation response in the whole blood of baboons and humans using impedance aggregometry. METHODS: Blood was drawn from 24 anesthetised male baboons and 25 healthy volunteers. The platelet aggregation response was determined by impedance aggregometry (Multiplate®). Platelets in the hirudinised whole blood samples were stimulated with four different activators: adenosine diphosphate (ADP), collagen (COL), thrombin receptor activating peptide-6 (TR1AP), and activation of PAR-4 thrombin receptor subtype (TR4AP) at standard concentrations. Higher than standard concentrations were tested in a subgroup of the animals. RESULTS: The cell counts showed no differences between baboons and humans. The platelet aggregation response was significantly lower in baboons compared to humans when stimulated with the platelet agonists ADP (p<0.0001), COL (p=0.021) and TR4AP (p<0.0001). TR1AP did not stimulate platelet aggregation in the baboon blood. Doubling the concentration of ADP and of TR4AP significantly increased the AUC compared to the standard concentration. In contrast, increased COL levels did not further increase the AUC. CONCLUSION: The current study revealed that testing the platelet function in baboon blood by impedance aggregometry is feasible with ADP, COL and TR4AP, but not with TR1AP. Compared to humans, the aggregation response is lower in baboons. Considering the limitations in accordance to these results, baboons might represent a potential species for further platelet research.

Effect of coagulation factor concentrate administration on ROTEM® parameters in major trauma.

BACKGROUND: Purified coagulation factor concentrates, such as fibrinogen concentrate (FC) and prothrombin complex concentrate (PCC) are increasingly used as haemostatic therapy for trauma-induced coagulopathy (TIC). The impact of FC and PCC administration on ROTEM parameters among patients with TIC has not been adequately investigated. METHODS: In this retrospective observational study, changes to ROTEM parameters, induced by three different therapeutic interventions, were investigated: patients receiving FC only (FC-group); patients treated with FC and PCC (FC + PCC-group) and patients treated with PCC only (PCC-group). RESULTS: The study population comprised 96 patients who were predominately male (69 [71.9 %]), median age was 45.0 (26.3-60.0) years, and the median injury severity score was 34.0 (25.0-44.5). Administration of FC resulted in a significant reduction of the clotting time (CT) in both the EXTEM and FIBTEM assays but had no effect on INTEM CT. Clot amplitude (CA) increased significantly in the FIBTEM assay but remained unchanged in the EXTEM and INTEM assays. The combined administration of FC and PCC increased FIBTEM maximum clot firmness (MCF) and normalized EXTEM CT but did not change either INTEM or FIBTEM CT. Following PCC therapy, EXTEM and FIBTEM CT normalized; CA at 10 min after CT measurements decreased significantly in EXTEM, INTEM and FIBTEM. CONCLUSIONS: Administration of FC alone or in combination with PCC resulted in a significant improvement of fibrin polymerisation as measured by an increase in FIBTEM MCF. CT is dependent not only on thrombin generation but also on the availability of substrate (fibrinogen). Accelerated fibrin polymerisation rate results in earlier clot formation and consequently shorter CT. PCC administration normalised EXTEM CT below the upper threshold of 80 s. This study was performed at the AUVA Trauma Centre Salzburg, Salzburg, Austria.

Blood biochemical changes in pigs after infusion with acetate-buffered or lactate-buffered crystalloid solutions.

Perioperative fluid therapy is an important component of many medical procedures with animals. Buffered crystalloid solutions avoid inducing metabolic acidosis, but lactated solutions can elevate blood lactate concentrations and acetated solutions have not been thoroughly investigated using large animals. Here, the authors compare blood biochemical parameters in 20 juvenile pigs after perioperative fluid administration of an acetate-buffered solution (Elo-Mel isoton, EMI) or a lactate-buffered solution (lactated Ringer's solution, LRS). The authors measured blood lactate, glucose and electrolyte concentrations before and after administering the test fluid during surgery. Blood lactate concentration after administration was significantly higher in pigs that received LRS than in pigs that received EMI, but glucose and electrolyte concentrations did not differ significantly between treatment groups before or after administration. These findings suggest that EMI might be a preferable option for perioperative fluid therapy in pigs.

Platelet function in reconstituted whole blood variants: An observational study over 5 days of storage time.

BACKGROUND: Platelet concentrates (PCs) are usually stored at room temperature under constant gentle agitation. Risk of bacterial contamination limits maximum storage time to 5 days. The objective of the study was to investigate platelet function with regard to storage time in different reconstituted whole blood (RWB) variants. METHODS: Donated apheresis PCs were stored at 22°C over 5 days. To obtain RWB, apheresis PCs were mixed with plasma-free packed red blood cells (RBCs) and either prethawed fresh frozen plasma (PT) or solvent-detergent plasma (SD) [1:1:1 ratio], or with leukocyte- and platelet-depleted whole blood (LD-WB) as control. Platelet function in RWB variants was assessed by impedance aggregometry (Multiplate) on Days 0, 1, 3, and 5 following platelet donation. RESULTS: Platelet aggregometry did not reach the lower limits determined from healthy volunteers in any of the RWB variants. Platelet aggregability measured by ASPI test, ADP test, and COL test declined over storage time in all RWB variants. No differences were observed in the TRAP test. At most measurement time points, LD-RWB provided significantly higher platelet aggregability compared with SD-RWB and PT-RWB (p < 0.01). SD-RWB demonstrated higher platelet aggregability on Day 0 in the ASPI test, ADP test, and TRAP test compared with PT-RWB. CONCLUSION: Apheresis PCs stored for 5 days at 22°C demonstrated reduced platelet aggregability, as measured by multiple electrode aggregometry when mixed with RBCs and plasma. As platelet aggregation in LD-RWB was superior compared with SD-RWB and PT-RWB variants, it might be possible that additives in RBCs or plasma are responsible for the observed depressed platelet function. Critical evaluation of current massive transfusion recommendations proposing early platelet transfusion is indicated.

Rapid measurement of fibrinogen concentration in whole blood using a steel ball coagulometer.

BACKGROUND: Fibrinogen plays a key role in hemostasis and is the first coagulation factor to reach critical levels in bleeding patients. Current European guidelines on the management of traumatic or perioperative bleeding recommend fibrinogen supplementation at specific threshold levels. Whole blood viscoelastic tests provide fast evaluation of fibrin deficits. Fast measurement of plasma fibrinogen concentration is not yet available. We investigated a method to rapidly determine whole blood fibrinogen concentration using standard Clauss assays and a steel ball coagulometer and provide an estimate of the "plasma-equivalent" fibrinogen concentration within minutes by adjustment of the measured whole blood fibrinogen concentration with a quickly measureable hemoglobin-derived hematocrit. METHODS: The feasibility of this approach was tested with a Clauss assay using multiple porcine fresh blood samples obtained during in vivo bleeding, hemodilution, and after treatment with hemostatic therapy. Two different Clauss assays were then tested using multiple human volunteers' blood samples diluted in vitro and supplemented with fibrinogen concentrate. Comparative measurements with fibrin-based thromboelastometry tests were performed. RESULTS: Regression and Bland-Altman analyses of derived "plasma-equivalent" fibrinogen and measured plasma fibrinogen concentration was excellent in porcine and human blood samples, especially in the ranges relevant to traumatic or perioperative bleeding. CONCLUSION: Fast whole blood fibrinogen measurements could be considered as an alternative to plasma fibrinogen measurement for acute bleeding management in trauma and perioperative care settings. Further studies are needed to prove this concept and determine the turnaround times for its clinical application in emergency departments and operating theaters.