Do not forget the platelets: The independent impact of red blood cell to platelet ratio on mortality in massively transfused trauma patients

Whole Blood and Blood Component Resuscitation in Trauma: Interaction and Association With Mortality

OBJECTIVE

To evaluate the interaction between whole blood (WB) and blood component resuscitation in relation to mortality after trauma.

BACKGROUND

WB is increasingly available in civilian trauma resuscitation, and it is typically transfused concomitantly with blood components. The interaction between WB and blood component transfusions is unclear.

METHODS

Adult patients with trauma with a shock index >1 who received ≥4 combined units of red blood cells and/or WB within 4 hours across 501 U.S. trauma centers were included using the American College of Surgeons Trauma Quality Improvement Program database. The associations between (1) WB resuscitation and mortality, (2) WB to total transfusion volume ratio (WB:TTV) and mortality, and (3) balanced blood component transfusion in the setting of combined WB and component resuscitation and mortality were evaluated with multivariable analysis.

RESULTS

A total of 12,275 patients were included (WB: 2884 vs component-only: 9391). WB resuscitation was associated with lower odds of 4-hour [adjusted odds ratio: 0.81 (0.68-0.97)], 24-hour, and 30-day mortality compared with component-only. Higher WB:TTV ratios were significantly associated with lower 4-hour, 24-hour, and 30-day mortality, with a 13% decrease in odds of 4-hour mortality for each 10% increase in the WB:TTV ratio [0.87 (95% CI: 0.80-0.94)]. Balanced blood component transfusion was associated with significantly lower odds of 4-hour [adjusted odds ratio: 0.45 (95% CI: 0.29-0.68)], 24-hour, and 30-day mortality in the setting of combined WB and blood component resuscitation.

CONCLUSIONS

WB resuscitation, higher WB:TTV ratios, and balanced blood component transfusion in conjunction with WB were associated with lower mortality in patients with trauma presenting in shock requiring at least 4 units of red blood cells and/or WB transfusion within 4 hours of arrival.

A Contemporary Review of Blood Transfusion in Critically Ill Patients

Blood transfusion is a common therapeutic intervention in hospitalized patients. There are numerous indications for transfusion, including anemia and coagulopathy with deficiency of single or multiple coagulation components such as platelets or coagulation factors. Nevertheless, the practice of transfusion in critically ill patients has been controversial mainly due to a lack of evidence and the need to consider the appropriate clinical context for transfusion. Further, transfusion carries many risk factors that must be balanced with benefits. Therefore, transfusion practice in ICU patients has constantly evolved, and we endeavor to present a contemporary review of transfusion practices in this population guided by clinical trials and expert guidelines.

Transfusion Practices in Severely Injured Patients at a Level 1 Trauma Center

Introduction

Acute trauma resuscitation is challenging and disorganized in low- and middle-income countries as there is lack of evidence-based transfusion practices with respect to ratio, volume, trigger, cutoff points for various triggers. This study aims to study the patterns of blood use in various mechanisms of injury, by interfacility transfer status and define triggers for transfusion of various blood components. Prospective observational study, emergency department of level 1 trauma center (August 2017-August 2018).

Methods

Demographic, injury, clinical, laboratory, transfusion characteristics, and patient outcomes were collected from electronic hospital records and transfusion service records. We used multivariate logistic regression to identify triggers of transfusion of red blood cells, plasma, platelets (PLTs), cryoprecipitate, and mortality predictors.

Results

Among 986 severely injured patients 80% were males, 92% had blunt injuries and commonest trauma was Head. The median length of intensive care unit stay and hospital stay were more in a referred group. Patients brought to center directly received more massive transfusions (56, 13.05% vs. 48, 8.62%). Railway track injuries received the most total median packed red blood cells (PRBCs) units in both groups. The triggers for various blood product transfusions include: Hematocrit < 32.08 for PRBC, PT >16.9 s for plasma, PLT count <130 lakhs for platelets, MAP <89.7 mmHg and PT >18.2 s for cryoprecipitate.

Conclusion

Railway track injuries with inferior extremity injuries required maximum transfusion requirements and were a trigger for PRBC, plasma, PLTs, and cryoprecipitate. Smartphone-based apps and transfusion prediction models can be framed based on the triggers and cut points.

Safety of the injectable expanding biopolymer foam for non-compressible truncal bleeding in swine

BACKGROUND

A novel hydrophobically modified chitosan (hm-chitosan) polymer has been previously shown to improve survival in a non-compressible intra-abdominal bleeding model in swine. We performed a 28-day survival study to evaluate the safety of the hm-chitosan polymer in swine.

METHODS

Female Yorkshire swine (40-50 kg) were used. A mild, non-compressible, closed-cavity bleeding model was created with splenic transection. The hm-chitosan polymer was applied intra-abdominally through an umbilical nozzle in the same composition and dose previously shown to improve survival. Animals were monitored intraoperatively and followed 28 days postoperatively for survival, signs of pain, and end-organ function. Gross pathological and microscopic evaluations were performed at the conclusion of the experiment.

RESULTS

A total of 10 animals were included (hm-chitosan = 8; control = 2). The 2 control animals survived through 28 days, and 7 of the 8 animals from the hm-chitosan group survived without any adverse events. One animal from the hm-chitosan group required early termination of the study for signs of pain, and superficial colonic ulcers were found on autopsy. Laboratory tests showed no signs of end-organ dysfunction after exposure to hm-chitosan after 28 days. On gross pathological examination, small (<0.5 cm) peritoneal nodules were noticed in the hm-chitosan group, which were consistent with giant-cell foreign body reaction in microscopy, presumably related to polymer remnants. Microscopically, no signs of systemic polymer embolization or thrombosis were noticed.

CONCLUSION

Prolonged intraperitoneal exposure to the hm-chitosan polymer was tolerated without any adverse event in the majority of animals. In the single animal that required early termination, the material did not appear to be associated with end-organ dysfunction in swine. Superficial colonic ulcers that would require surgical repair were identified in 1 out of 8 animals exposed to hm-chitosan.

Optimal dose of cryoprecipitate in massive transfusion following trauma

BACKGROUND

While cryoprecipitate (Cryo) is commonly included in massive transfusion protocols for hemorrhagic shock, the optimal dose of Cryo transfusion remains unknown. We evaluated the optimal red blood cell (RBC) to RBC to Cryo ratio during resuscitation in massively transfused trauma patients.

METHODS

Adult patients in the American College of Surgeon Trauma Quality Improvement Program (2013-2019) receiving massive transfusion (≥4 U of RBCs, ≥1 U of fresh frozen plasma, and ≥1 U of platelets within 4 hours) were included. A unit of Cryo was defined as a pooled unit of 100 mL. The RBC:Cryo ratio was calculated for blood products transfused within 4 hours of presentation. The association between RBC:Cryo and 24-hour mortality was analyzed with multivariable logistic regression adjusting for the volume of RBC, plasma and platelet transfusions, global and regional injury severity, and other relevant variables.

RESULTS

The study cohort included 12,916 patients. Among those who received Cryo (n = 5,511 [42.7%]), the median RBC and Cryo transfusion volume within 4 hours was 11 U (interquartile range, 7-19 U) and 2 U (interquartile range, 1-3 U), respectively. Compared with no Cryo administration, only RBC:Cryo ratios ≤8:1 were associated with a significant survival benefit, while lower doses of Cryo (RBC:Cryo >8:1) were not associated with decreased 24-hour mortality. Compared with the maximum dose of Cryo administration (RBC:Cryo, 1:1-2:1), there was no difference in 24-hour mortality up to RBC:Cryo of 7:1 to 8:1, whereas lower doses of Cryo (RBC:Cryo, >8:1) were associated with significantly increased 24-hour mortality.

CONCLUSION

One pooled unit of Cryo (100 mL) per 7 to 8 U of RBCs could be the optimal dose of Cryo in trauma resuscitation that provides a significant survival benefit while avoiding unnecessary blood product transfusions.

LEVEL OF EVIDENCE

Prognostic and Epidemiologic; Level IV.

Platelet-inspired synthetic nanoparticles improve hemostasis and hemodynamics in a rabbit model of abdominal hemorrhage

BACKGROUND

Early platelet transfusion is associated with reduced mortality in traumatic hemorrhage. However, platelet usage is severely limited because of the challenges of donor availability, platelet portability, and storage. Here, we report on a bioinspired synthetic platelet (SP) nanoconstruct that utilizes liposome surface-decoration with peptides that mimic injury site-specific platelet adhesion to von Willebrand Factor and collagen, and fibrinogen-mediated platelet aggregation. Synthetic platelet has previously shown promising hemostatic outcomes in vitro and in vivo. Here, we evaluated hemostasis and hemodynamic effects of SP in a rabbit model of abdominal hemorrhage.

METHODS

Twenty-three adult male New Zealand white rabbits (2.5-3.5 kg) were treated with either buffer, control particles (CPs), or SP. Under general anesthesia with invasive monitoring, rabbits underwent laparotomy with combined splenic and hepatic injury. Hemodynamics were monitored for 30 minutes and blood loss was quantified. Blood counts, aggregometry, catecholamine and platelet factor 4 (PF4) assays were performed at multiple timepoints. Analysis used analysis of variance and post hoc Tukey testing with α = 0.05.

RESULTS

Rabbits in the SP (n = 7) group had significantly lower weight-normalized blood loss compared with both buffer (n = 8) and CP (n = 8) animals (21.1 vs. 33.2 vs. 40.4 g/kg, p < 0.001). Synthetic platelet-treated animals had higher systolic blood pressure area under curve compared with buffer- and CP-treated animals (1567 vs. 1281 vs. 1109 mm Hg*min, p = 0.006), although post hoc differences were only significant for the SP/CP comparison ( p = 0.005). Platelet counts, catecholamine levels, PF4, and aggregometry were similar between groups.

CONCLUSION

Synthetic platelet treatment significantly reduced blood loss and improved hemodynamics in a rabbit abdominal hemorrhage model. Synthetic platelet has potential as an intravenous hemostatic platelet surrogate with donor-independent availability and scalable manufacture.

Achieving balanced transfusion early in critically bleeding trauma patients: an observational study exploring the effect of attending trauma surgical presence during resuscitation

Background

After 15 years of damage control resuscitation (DCR), studies still report high mortality rates for critically bleeding trauma patients. Adherence to massive hemorrhage protocols (MHPs) based on a 1:1:1 ratio of plasma, platelets, and red blood cells (RBCs) as part of DCR has been shown to improve outcomes. We wanted to assess MHP use in the early (6 hours from admission), critical phase of DCR and its impact on mortality. We hypothesized that the presence of an attending trauma surgeon during all MHP activations from 2013 would contribute to improving institutional resuscitation strategies and patient outcomes.

Methods

We conducted a retrospective analysis of all trauma patients receiving ≥10 RBCs within 6 hours of admission and included in the institutional trauma registry between 2009 and 2019. The cohort was divided in period 1 (P1): January 2009-August 2013, and period 2 (P2): September 2013-December 2019 for comparison of outcomes.

Results

A total of 141 patients were included, 81 in P1 and 60 in P2. Baseline characteristics were similar between the groups for Injury Severity Score, lactate, Glasgow Coma Scale, and base deficit. Patients in P2 received more plasma (16 units vs. 12 units; p<0.01), resulting in a more balanced plasma:RBC ratio (1.00 vs. 0.74; p<0.01), and platelets:RBC ratio (1.11 vs. 0.92; p<0.01). All-cause mortality rates decreased from P1 to P2, at 6 hours (22% to 8%; p=0.03), at 24 hours (36% vs 13%; p<0.01), and at 30 days (48% vs 30%, p=0.03), respectively. A stepwise logistic regression model predicted an OR of 0.27 (95% CI 0.08 to 0.93) for dying when admitted in P2.

Conclusions

Achieving balanced transfusion rates at 6 hours, facilitated by the presence of an attending trauma surgeon at all MHP activations, coincided with a reduction in all-cause mortality and hemorrhage-related deaths in massively transfused trauma patients at 6 hours, 24 hours, and 30 days.

Level of evidence

IV.

Cryopreserved Platelets in a Non-Toxic DMSO-Free Solution Maintain Hemostatic Function In Vitro

Dimethyl sulfoxide (DMSO) is regularly used as a cryoprotectant agent for the cryopreservation of platelets. However, DMSO is considered toxic. We therefore hypothesized that saline could be used as a non-toxic medium for the cryopreservation of platelets. Double-dose buffy coat platelets (n = 10) were divided and cryopreserved at -80 °C using 5-6% dimethyl sulfoxide (DMSO) or in NaCl (9 mg/mL). Paired testing was conducted pre-freeze, post-thaw (PT 1 h). Upon analysis, each bag was thawed and reconstituted in fresh plasma. Analyses included cell counts and the metabolic, phenotypic, and functional properties of the platelets together with thromboelastometry. The cryopreserved platelets showed several biochemical and ultrastructural changes compared to pre-freezing. Platelet recovery was approximately 17% higher in DMSO-free units (p < 0.001), but the platelet viability was reduced (p < 0.001). However, using controlled freezing (n = 6), the platelet viability was improved. The clot formation time (CFT) was comparable, but DMSO-free platelets showed slightly decreased maximum clot firmness (MCF) (p = 0.034). By reducing the reconstituted plasma volume, a reduced CFT and increased MCF were obtained (p < 0.001). This study demonstrates that platelets can be cryopreserved in saline without the addition of DMSO, with high recovery and maintained hemostatic function. However, controlled freezing is required to optimize platelet quality.

The European guideline on management of major bleeding and coagulopathy following trauma: sixth edition

BACKGROUND

Severe trauma represents a major global public health burden and the management of post-traumatic bleeding continues to challenge healthcare systems around the world. Post-traumatic bleeding and associated traumatic coagulopathy remain leading causes of potentially preventable multiorgan failure and death if not diagnosed and managed in an appropriate and timely manner. This sixth edition of the European guideline on the management of major bleeding and coagulopathy following traumatic injury aims to advise clinicians who care for the bleeding trauma patient during the initial diagnostic and therapeutic phases of patient management.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma included representatives from six European professional societies and convened to assess and update the previous version of this guideline using a structured, evidence-based consensus approach. Structured literature searches covered the period since the last edition of the guideline, but considered evidence cited previously. The format of this edition has been adjusted to reflect the trend towards concise guideline documents that cite only the highest-quality studies and most relevant literature rather than attempting to provide a comprehensive literature review to accompany each recommendation.

RESULTS

This guideline comprises 39 clinical practice recommendations that follow an approximate temporal path for management of the bleeding trauma patient, with recommendations grouped behind key decision points. While approximately one-third of patients who have experienced severe trauma arrive in hospital in a coagulopathic state, a systematic diagnostic and therapeutic approach has been shown to reduce the number of preventable deaths attributable to traumatic injury.

CONCLUSION

A multidisciplinary approach and adherence to evidence-based guidelines are pillars of best practice in the management of severely injured trauma patients. Further improvement in outcomes will be achieved by optimising and standardising trauma care in line with the available evidence across Europe and beyond.

Cryopreserved platelets in bleeding management in remote hospitals: A clinical feasibility study in Sweden

Background

Balanced transfusions, including platelets, are critical for bleeding patients to maintain hemostasis. Many rural hospitals have no or limited platelet inventory, with several hours of transport time from larger hospitals. This study aimed to evaluate the feasibility of using cryopreserved platelets that can be stored for years, in remote hospitals with no or limited platelet inventory.

Material and methods

Three remote hospitals participated in a prospective study including adult bleeding patients where platelet transfusions were indicated. Cryopreserved platelets were prepared in a university hospital, concentrated in 10 ml, transported on dry ice, and stored at -80°C at the receiving hospital. At request, the concentrated platelet units were thawed and diluted in fresh frozen plasma. The indications, blood transfusion needs, and laboratory parameters pre- and post-transfusion, as well as logistics, such as time from request to transfusion and work efforts in preparing cryopreserved platelets, were evaluated.

Results

Twenty-three bleeding patients were included. Nine patients (39%) were treated for gastrointestinal bleeding, five (22%) for perioperative bleeding, and four (17%) for trauma bleeding. The transfusion needs were 4.9 ± 3.3 red blood cell units, 3.2 ± 2.3 plasma units, and 1.9 ± 2.2 platelet units, whereof cryopreserved were 1.5 ± 1.1 (mean ± SD). One patient had a mild allergic reaction. We could not show the difference in laboratory results between pre- and post-transfusion of the cryopreserved units in the bleeding patients. The mean time from the order of cryopreserved platelets to transfusion was 64 min, with a range from 25 to 180 min.

Conclusion

Cryopreserved platelets in remote hospitals are logistically feasible in the treatment of bleeding. The ability to have platelets in stock reduces the time to platelet transfusion in bleeding patients where the alternative often is many hours delay. Clinical effectiveness and safety previously shown in other studies are supported in this small feasibility study.

Balanced blood component resuscitation in trauma: Does it matter equally at different transfusion volumes?

BACKGROUND

It remains unclear whether the association between balanced blood component transfusion and lower mortality is generalizable to trauma patients receiving varying transfusion volumes. We sought to study the role red blood cell transfusion volume plays in the relationships between red blood cell:platelet and red blood cell:fresh frozen plasma ratios and 4-hour mortality.

METHODS

Adult patients in the 2013 to 2018 American College of Surgeons Trauma Quality Improvement Program database receiving ≥6 red blood cell, ≥1 platelet, and ≥1 fresh frozen plasma within 4 hours were included. The following 4 cohorts were defined based on 4-hour red blood cell transfusion volume: (1) 6 to 10 units, (2) 11 to 15 units, (3) 16 to 20 units, and (4) >20 units. The association between red blood cell:fresh frozen plasma, red blood cell:platelet, and 4-hour mortality was evaluated discretely for each red blood cell transfusion volume category, statistically adjusting for confounders.

RESULTS

A total of 14,549 patients were included. In patients receiving 6 to 10 units of red blood cells, red blood cell:platelet ratios were not associated with 4-hour mortality, and only red blood cell:fresh frozen plasma ≥4:1 were associated with significantly higher odds of 4-hour mortality compared to 1:1. For patients receiving >10 red blood cell units, increasing red blood cell:platelet and red blood cell:fresh frozen plasma ratios were consistently associated with increased odds of 4-hour mortality. For example, in red blood cell volumes of 11 to 15, 16 to 20, and >20 units, risk-adjusted 4-hour mortality odds ratios for red blood cell:platelet ≥4:1 were 2.27 (1.47-3.51), 3.32 (2.26-4.90), and 3.01 (2.33-3.88), respectively.

CONCLUSION

The association between balanced blood component transfusion and 4-hour mortality is not homogenous in trauma patients requiring different transfusion volumes and is specifically less evident in patients receiving lower volumes. Such findings should be considered in the current and future blood shortage crises across the nation.

Platelet Transfusion for Trauma Resuscitation

Purpose of Review

To review the role of platelet transfusion in resuscitation for trauma, including normal platelet function and alterations in behavior following trauma, blood product transfusion ratios and the impact of platelet transfusion on platelet function, platelet function assays, risks of platelet transfusion and considerations for platelet storage, and potential adjunct therapies and synthetic platelets.

Recent Findings

Platelets are a critical component of clot formation and breakdown following injury, and in addition to these hemostatic properties, have a complex role in vascular homeostasis, inflammation, and immune function. Evidence supports that platelets are activated following trauma with several upregulated functions, but under conditions of severe injury and shock are found to be impaired in their hemostatic behaviors. Platelets should be transfused in balanced ratios with red blood cells and plasma during initial trauma resuscitation as this portends improved outcomes including survival. Multiple coagulation assays can be used for goal-directed resuscitation for traumatic hemorrhage; however, these assays each have drawbacks in terms of their ability to measure platelet function. While resuscitation with balanced transfusion ratios is supported by the literature, platelet transfusion carries its own risks such as bacterial infection and lung injury. Platelet supply is also limited, with resource-intensive storage requirements, making exploration of longer-term storage options and novel platelet-based therapeutics attractive. Future focus on a deeper understanding of the biology of platelets following trauma, and on optimization of novel platelet-based therapeutics to maintain hemostatic effects while improving availability should be pursued.

Summary

While platelet function is altered following trauma, platelets should be transfused in balanced ratios during initial resuscitation. Severe injury and shock can impair platelet function, which can persist for several days following the initial trauma. Assays to guide resuscitation following the initial period as well as storage techniques to extend platelet shelf life are important areas of investigation.