Hypobaria During Aeromedical Evacuation and Systemic Inflammation after Porcine Traumatic Brain Injury

BACKGROUND

Traumatic brain injury (TBI)-related morbidity is caused largely by secondary injury resulting from hypoxia, excessive sympathetic drive, and uncontrolled inflammation. Aeromedical evacuation (AE) is utilized by the military for transport of wounded soldiers to higher levels of care. We hypothesized that the hypobaric, hypoxic conditions of AE may exacerbate uncontrolled inflammation following TBI that could contribute to more severe TBI-related secondary injury.

STUDY DESIGN

Thirty-six female pigs were used to test TBI vs. TBI sham, hypoxia vs. normoxia, and hypobaria vs. ground conditions. TBI was induced by controlled cortical injury, hypobaric conditions of 12,000 feet were established in an altitude chamber, and hypoxic exposure was titrated to 85% SpO2 while at altitude. Serum cytokines, UCH-L1 and TBI biomarkers were analyzed via ELISA. Gross analysis and staining of cortex and hippocampus tissue was completed for glial fibrillary acidic protein (GFAP) and phosphorylated tau (p-tau).

RESULTS

Serum IL-1b, IL-6, and TNFα were significantly elevated following TBI in pigs exposed to altitude-induced hypobaria/hypoxia, as well as hypobaria alone, compared to ground level/normoxia. No difference in TBI biomarkers following TBI or hypobaric, hypoxic exposure was noted. No difference in brain tissue GFAP or p-tau when comparing the most different conditions of sham TBI+ground/normoxia to the TBI+hypobaria/hypoxia group was noted.

CONCLUSION

The hypobaric environment of AE induces systemic inflammation following TBI. Severe inflammation may play a role in exacerbating secondary injury associated with TBI and contribute to worse neurocognitive outcomes. Measures should be taken to minimize barometric and oxygenation changes during AE following TBI.

Direct red blood cell effect on thrombosis is dependent on the interaction of tissue factor and calcium with membrane phosphatidylserine

BACKGROUND

Prior literature has implicated Red Blood Cells (RBCs) in the initiation of thrombosis and suggests that post-transfusion hypercoagulability may occur secondary to the effects of RBCs. Elevated serum tissue factor is a known sequelae of acute trauma. Phosphatidylserine is a pro-thrombotic phospholipid present within the RBC cell membrane. We hypothesized that RBC aggregation is dependent on the interaction between RBC membrane bound (exposed) PS, extracellular calcium, and tissue factor.

METHODS

Human whole blood (WB) was separated into components including red blood cells (RBC) and platelet-rich plasma (PRP). WB, PRP, and RBCs underwent impedance aggregometry utilizing arachidonic acid (AA), ADP, collagen, calcium, and tissue factor (TF)-based agonists. RBCs then underwent impedance aggregometry utilizing combined calcium and TF agonists. RBCs were pre-treated with Annexin V, a known PS blocking agent, and underwent impedance aggregometry with combined calcium and TF agonists to determine if the mechanism of calcium/TF-induced RBC aggregability is dependent on PS. RBCs treated with calcium, TF, calcium+TF, and pre-treated with Annexin V followed by calcium+TF were perfused through an in vitro model of pulmonary microcirculatory flow.

RESULTS

RBC aggregation was significantly higher than that of WB and PRP when utilizing a TF agonist, an effect unique to TF. The combination of calcium and TF demonstrated significantly higher RBC aggregation than either agonist alone. Pre-treatment with Annexin V resulted in a significantly reduced aggregability of RBC following treatment with TF + calcium. RBCs aged to 42 days did not exhibit significant change in aggregation. Exposure to calcium and TF significantly reduced time to thrombosis of RBCs perfused through a pulmonary microcirculatory model.

CONCLUSION

Treatment with both TF and calcium synergistically induces RBC aggregation. PS appears to play an integral role in the TF/calcium-based, age-independent RBC aggregation response. RBCs treated with TF + calcium exhibit more rapid thrombus formation in an in vitro model of pulmonary microcirculatory perfusion.Study Type: human sample-based study.

LEVEL OF EVIDENCE

basic science paper.

Microvesicles from stored red blood cells induce P-selectin and von Willebrand factor release from endothelial cells via a protein kinase C-dependent mechanism

INTRODUCTION

The use of packed red blood cells (pRBCs) for resuscitation is limited by the red blood cell storage lesion, a series of biochemical and physiological changes that occur during the storage and aging of blood. Microvesicles (MVs) shed from pRBCs during this process are one component of the red blood cell storage lesion and lead to acute lung injury and pulmonary vascular microthrombi. We hypothesized that MVs from stored pRBCs lead to the release of P-selectin and von Willebrand factor (vWF) from endothelial cells and that this mechanism is mediated via activation of protein kinase C (PKC) or protein kinase A (PKA).

METHODS

Leukoreduced, platelet-poor murine pRBCs were isolated from C57BL/6 8-12 week-old male mice via cardiac puncture, prepared via centrifugation using a Ficoll gradient, and stored for up to 14 days, the equivalent of 42 days of storage in humans. MVs were isolated from the stored pRBC units via sequential high-speed centrifugation. Murine lung endothelial cells (MLECs) were cultured and grown to confluence, then treated with MVs and either calphostin C, a PKC inhibitor (10 μg/mL), or PKI 14-22 amide, a PKA inhibitor (10 μM). The supernatant was collected after 1 h. P-selectin and vWF A2 concentrations were quantified via ELISA. Immunofluorescent staining for vWF was performed on MLECs. Statistical analysis was performed via unpaired t-test or ANOVA as indicated and reported as mean ± SD. Concentration is reported as pg/mL.

RESULTS

MLECs treated with MVs isolated from stored pRBCs demonstrated increased release of P-selectin and vWF A2 in a dose-dependent fashion. MLECs treated with MVs prepared from stored as compared to fresh pRBCs demonstrated increased release of P-selectin (3751 ± 726 vs 359 ± 64 pg/mL, p < 0.0001) and vWF A2 (3141 ± 355 vs 977 ± 75 pg/mL, p < 0.0001) with increasing duration of storage. The treatment of MVs with calphostin C decreased the amount of P-selectin (1471 ± 444 vs 3751 ± 726 pg/mL, p < 0.0001) and VWF A2 (2401 ± 289 vs 3141 ± 355 pg/mL, p = 0.0017) released into the supernatant by MLECs compared to MVs alone. The treatment of MVs with PKI 14-22 increased the amount of P-selectin released compared to MVs alone (1999 ± 67 vs 1601 ± 135 pg/mL, p = 0.0018).

CONCLUSIONS

MVs from stored pRBCs stimulate the release of P-selectin and VWF A2 from endothelial cells. The effect of MVs increases with both dose of MVs and age of stored pRBCs from which they are formed. This mechanism is dependent on activation of PKC and inhibition of this enzyme represents a potentially significant strategy to modulate the inflammatory response to resuscitation with stored pRBCs.

Murine Traumatic Brain Injury Model Comparison: Closed Head Injury Versus Controlled Cortical Impact

INTRODUCTION

Various murine models have been utilized to study TBI, including closed head injury (CHI) and controlled cortical impact (CCI), without direct comparison. The aim of our study was to evaluate these models to determine differences in neurological and behavioral outcomes postinjury.

METHODS

Male C57B/6 mice (9-10 wk) were separated into six groups including: untouched, sham craniotomy (4 mm), CCI 0.9 mm depth of impact, CCI 1.6 mm, CCI 2.2 mm, and CHI. CCI was performed using a 3 mm impact tip at a velocity of 5 m/s, dwell time of 250 ms, and depth as noted above. CHI was completed with a centered 400 g weight drop from 1 cm height. Mice were survived to 14-d (n = 5 per group) and 30-d (n = 5 per group) respectively for histological analysis of p-tau within the hippocampus. These mice underwent Morris Water Maze memory testing and Rotarod motor testing. Serum was collected from a separate cohort of mice (n = 5 per group) including untouched, isoflurane only, CCI 1.6 mm, CHI at 1, 4, 6, and 24 h for analysis of neuron specific enolase and glial fibrillary acidic protein (GFAP) via ELISA. Laser speckle contrast imaging was analyzed prior to and after impact in the CHI and CCI 1.6 mm groups.

RESULTS

There were no significant differences in Morris Water Maze or Rotarod testing times between groups at 14- or 30-d. P-tau was significantly elevated in all groups except CCI 1.6 mm contralateral and CCI 2.2 mm ipsilateral compared to untouched mice at 30-d. P-tau was also significantly elevated in the CHI group at 30 d compared to CCI 1.6 mm contralateral and CCI 2.2 mm on both sides. GFAP was significantly increased in mice undergoing CHI (9959 ± 91 pg/mL) compared to CCI (2299 ± 1288 pg/mL), isoflurane only (133 ± 75 pg/mL), and sham (86 ± 58 pg/mL) at 1-h post TBI (P < 0.0001). There were no differences in serum neuron specific enolase levels between groups. Laser doppler imaging demonstrated similar decreases in cerebral blood flow between CHI and CCI; however, CCI mice had a reduction in blood flow with craniotomy only that did not significantly decrease further with impact.

CONCLUSIONS

Based on our findings, CHI leads to increased serum GFAP levels and increased p-tau within the hippocampus at 30-d postinjury. While CCI allows the comparison of one cerebral hemisphere to the other, CHI may be a better model of TBI as it requires less technical expertise and has similar neurological outcomes in these murine models.

Desmopressin, Misoprostol, nor Carboprost Affect Platelet Aggregability Following Traumatic Brain Injury and Aspirin

INTRODUCTION

Desmopressin (DDAVP) has been utilized clinically in patients taking aspirin (ASA) to improve drug-induced platelet dysfunction. Misoprostol and carboprost, prostaglandin analogs commonly used for postpartum hemorrhage, may also induce platelet aggregation. The aim of this study was to determine the effects of DDAVP, misoprostol, and carboprost administration on platelet aggregability following traumatic brain injury (TBI) in mice treated with ASA.

METHODS

Male C57BL/6 mice were randomized into seven groups (n = 5 each): untouched, ASA only, Saline/TBI, ASA/TBI, ASA/TBI/DDAVP 0.4 μg/kg, ASA/TBI/misoprostol 1 mg/kg, and ASA/TBI/carboprost 100 μg/kg. TBI was induced via a weight drop model 4-h after ASA (50 mg/kg) gavage. Mice were given an intraperitoneal injection of DDAVP, misoprostol, or carboprost 10 minutes after TBI. In vivo testing was completed utilizing tail vein bleed. Mice were sacrificed 30-min posttreatment and blood was collected via cardiac puncture. Whole blood was analyzed via Multiplate impedance aggregometry, rotational thromboelastometry, and TEG6s.

RESULTS

Mice receiving misoprostol after ASA/TBI demonstrated decreased tail vein bleeding times compared to ASA only treated mice. However, mice treated with misoprostol following ASA and TBI demonstrated decreased platelet aggregability compared to untouched mice and TBI only mice within the arachidonic acid agonist pathway. By contrast, DDAVP and carboprost did not significantly change platelet aggregability via adenosine diphosphate or arachidonic acid following ASA and TBI. However, DDAVP did decrease the platelet contribution to clot via rotational thromboelastometry.

CONCLUSIONS

Reversal of medication-induced platelet inhibition has become increasingly controversial after TBI. Based on these results, DDAVP, misoprostol, nor carboprost consistently improve platelet aggregability following TBI in those also treated with ASA.

Syndecan-1 as the Effect or Effector of the Endothelial Inflammatory Response?

INTRODUCTION

Syndecan-1 is a heparan sulfate proteoglycan found in the glycocalyx of vascular endothelial cells. Serum levels of syndecan-1 have repeatedly been demonstrated to increase following traumatic injury and shock, but it is unclear whether syndecan-1 plays an active role in the inflammatory response or is simply a biomarker of a state of hypoperfusion. The aim of this study was to identify the role of syndecan-1 role in the inflammatory process in the absence of trauma.

METHODS

Male mice were randomized into five groups (n = 3). Four groups received increasing concentrations of syndecan-1 (1, 10, 100, and 1000pg/mL per blood volume) and a fifth group was given normal saline as a control via intravenous injection. These concentrations were selected based on previous syndecan-1 enzyme-linked immunosorbent assay data acquired following induced hemorrhagic shock in mice resulting in serum levels of 10-6000 pg/mL. Mice from each group were sacrificed at 1-, 4-, and 24-h time points for serum biomarker evaluation. A multiplex enzyme-linked immunosorbent assay was performed to analyze proinflammatory cytokines and chemokines including interleukin (IL)-1a, IL-1b, IL-2, IL-3, IL-4, IL-6, IL-10, IL-12, IL-17, monocyte chemoattractant protein-1, TNF-α, macrophage inflammatory protein-1α, granulocyte-macrophage colony-stimulating factor, and normal T cell expressed and presumably secreted levels. Whole blood was analyzed via rotational thromboelastometry in a separate group of mice dosed with syndecan-1 at 1000 pg/mL and compared to sham mice at 1 h.

RESULTS

Tumor necrosis factor-α was significantly elevated in the 1000 pg/mL group compared to sham animals. There were no significant changes in IL-1a, IL-1b, IL-2, IL-3, IL-4, IL-6, IL-10, IL-12, monocyte chemoattractant protein--1, macrophage inflammatory protein-1α, granulocyte-macrophage colony-stimulating factor, or normal T cell expressed and presumably secretedat 1, 4, and 24 h for any group when compared to mice receiving saline alone. No significant differences were noted in coagulability between the 1000 pg/mL syndecan-1 group and shams at 1 h CONCLUSIONS: Inflammatory cytokine concentrations did not change with increasing dosage of syndecan-1 within mice at any timepoint, except for an acute change in tumor necrosis factor-α which was transient. Based on our results, syndecan-1 appears to be a biomarker for inflammation rather than an active participant in eliciting an inflammatory response. Further research will focus on the role of syndecan-1 following hemorrhagic shock.

Quality of Integration of Air Force Trauma Surgeons Within the Center for Sustainment of Trauma and Readiness Skills, Cincinnati: A Pilot Study

INTRODUCTION

While previous studies have analyzed military surgeon experience within military-civilian partnerships (MCPs), there has never been an assessment of how well military providers are integrated within an MCP. The Center for Sustainment of Trauma and Readiness Skills, Cincinnati supports the Critical Care Air Transport Advanced Course and maintains the clinical skills of its staff by embedding them within the University of Cincinnati Medical Center. We hypothesized that military trauma surgeons are well integrated within University of Cincinnati Medical Center and that they are exposed to a similar range of complex surgical pathophysiology as their civilian partners.

MATERIALS AND METHODS

After Institutional Review Board approval, Current Procedural Terminology (CPT) codes were abstracted from billing data for trauma surgeons covering University of Cincinnati Hospitals in 2019. The number of trauma resuscitations and patient acuity metrics were abstracted from the Trauma Registry and surgeon Knowledge, Skills, and Abilities clinical activity (KSA-CA) scores were calculated using their CPT codes. Finally, surgeon case distributions were studied by sorting their CPT codes into 23 categories based on procedure type and anatomic location. Appropriate, chi-squared or Mann-Whitney U-tests were used to compare these metrics between the military and civilian surgeon groups and the metrics were normalized by the group's full-time equivalent (FTE) to adjust for varying weeks on service between groups.

RESULTS

Data were available for two active duty military and nine civilian staff. The FTEs were significantly lower in the military group: military 0.583-0.583 (median 0.583) vs. civilian 0.625-1.165 (median 1.0), P = 0.04. Per median FTE and surgeon number, both groups performed a similar number of trauma resuscitations (civilian 214 ± 54 vs. military 280 ± 13, P = 0.146) and KSA-CA points (civilian 55,629 ± 25,104 vs. military 36,286 ± 11,267; P = 0.582). Although the civilian surgeons had a higher proportion of hernia repairs (P < 0.001) and laparoscopic procedures (P = 0.006), the CPT code categories most relevant to combat surgery (those relating to solid organ, hollow viscus, cardiac, thoracic, abdominal, and tissue debridement procedures) were similar between the surgeon groups. Finally, patient acuity metrics were similar between groups.

CONCLUSION

This is the first assessment of U.S. Air Force trauma surgeon integration relative to their civilian partners within an MCP. Normalized by FTE, there was no difference between the two groups' trauma experience to include patient acuity metrics and KSA-CA scores. The proportion of CPT codes that was most relevant to expeditionary surgery was similar between the military and civilian partners, thus optimizing the surgical experience for the military trauma surgeons within University of Cincinnati Medical Center. The methods used within this pilot study can be generalized to any American College of Surgeons verified Trauma Center MCP, as standard databases were used.

Effectiveness of Negative Pressure Wound Therapy During Aeromedical Evacuation Following Soft Tissue Injury and Infection

INTRODUCTION

Negative pressure wound therapy (NPWT) is utilized early after soft tissue injury to promote tissue granulation and wound contraction. Early post-injury transfers via aeromedical evacuation (AE) to definitive care centers may actually induce wound bacterial proliferation. However, the effectiveness of NPWT or instillation NPWT in limiting bacterial proliferation during post-injury AE has not been studied. We hypothesized that instillation NPWT during simulated AE would decrease bacterial colonization within simple and complex soft tissue wounds.

METHODS

The porcine models were anesthetized before any experiments. For the simple tissue wound model, two 4-cm dorsal wounds were created in 34.9 ± 0.6 kg pigs and were inoculated with Acinetobacter baumannii (AB) or Staphylococcus aureus 24 hours before a 4-hour simulated AE or ground control. During AE, animals were randomized to one of the five groups: wet-to-dry (WTD) dressing, NPWT, instillation NPWT with normal saline (NS-NPWT), instillation NPWT with Normosol-R® (NM-NPWT), and RX-4-NPWT with the RX-4 system. For the complex musculoskeletal wound, hind-limb wounds in the skin, subcutaneous tissue, peroneus tertius muscle, and tibia were created and inoculated with AB 24 hours before simulated AE with WTD or RX-4-NPWT dressings. Blood samples were collected at baseline, pre-flight, and 72 hours post-flight for inflammatory cytokines interleukin (IL)-1β, IL-6, IL-8 and tumor necrosis factor alpha. Wound biopsies were obtained at 24 hours and 72 hours post-flight, and the bacteria were quantified. Vital signs were measured continuously during simulated AE and at each wound reassessment.

RESULTS

No significant differences in hemodynamics or serum cytokines were noted between ground or simulated flight groups or over time in either wound model. Simulated AE alone did not affect bacterial proliferation compared to ground controls. The simple tissue wound arm demonstrated a significant decrease in Staphylococcus aureus and AB colony-forming units at 72 hours after simulated AE using RX-4-NPWT. NS-NPWT during AE more effectively prevented bacterial proliferation than the WTD dressing. There was no difference in colony-forming units among the various treatment groups at the ground level.

CONCLUSION

The hypoxic, hypobaric environment of AE did not independently affect the bacterial growth after simple tissue wound or complex musculoskeletal wound. RX-4-NPWT provided the most effective bacterial reduction following simulated AE, followed by NS-NPWT. Future research will be necessary to determine ideal instillation fluids, negative pressure settings, and dressing change frequency before and during AE.

Predictive Value of Early Inflammatory Markers in Trauma Patients Based on Transfusion Status

INTRODUCTION

Seven key inflammatory biomarkers were recently found to be associated with the risk of mortality in a multicenter study of massively transfused patients. The aim of this prospective single-center study was to determine which of these early inflammatory markers could predict 30-d mortality among all critically injured trauma patients.

METHODS

Serum samples were collected at 6, 24, and 72 h from 238 consecutive patients admitted to the intensive care unit following traumatic injury. Inflammatory markers syndecan-1, eotaxin, IL-1ra, IL-6, IL-8, IL-10, IP-10, and MCP-1 were analyzed via multiplex enzyme-linked immunosorbent assay. Subgroup analysis was performed for patients undergoing massive transfusion (≥5 red blood cells), submassive transfusion (1-4 red blood cells), or no transfusion during the first 4 h postinjury. The primary outcome of 30-d survival was modeled as a function of each biomarker and confounders using repeat measures logistic regression.

RESULTS

Patients had a median age of 51.3 y [33.7, 70.2], 70.6% were male, 17.4% experienced penetrating trauma, and had a median injury severity score of 22 [14, 33]. IL-1ra, IL-8, IL-10, and MCP-1 were significantly increased during the first 72 h in nonsurvivors (n = 31). Elevated IL-1ra, IL-8, IL-10, and MCP-1 at 6 h postinjury were associated with 30-d mortality. By contrast, serum syndecan-1 and eotaxin levels were not associated with mortality at any time point. IL-8 and lactate were increased at 6 h in 30-d nonsurvivors for patients receiving submassive transfusion (n = 78).

CONCLUSIONS

Early evaluations of IL-1ra, IL-8, IL-10, and IP-10 within 6 h of injury are useful predictors of 30-d mortality. Subgroup analysis suggests that transfusion status does not significantly affect early inflammatory markers.

LEVEL OF EVIDENCE

Level III, prognostic/epidemiological.

Descriptive Analysis of Intratheater Critical Care Air Transport Team Patient Movements During Troop Drawdown: Afghanistan (2017-2019)

BACKGROUND

The majority of critical care air transport (CCAT) flights are regulated, meaning that a theater-validating flight surgeon has confirmed that the patient is medically cleared for flight and that evacuation is appropriate. If the conditions on the ground do not allow for this process, the flight is unregulated. Published data are limited regarding CCAT unregulated missions to include the period of troop drawdown at the end of the Afghanistan conflict. The objective of our study was to characterize the unregulated missions within Afghanistan during troop drawdown and compare them to regulated missions during the same timeframe.

STUDY DESIGN

We performed a retrospective review of all CCAT medical records of patients transported via CCAT within Afghanistan between January 2017 and December 2019. We abstracted data from the records, including mission characteristics, patient demographics, injury descriptors, preflight military treatment facility procedures, CCAT procedures, in-flight CCAT treatments, in-flight events, and equipment issues. Following descriptive and comparative analysis, a Cochran-Armitage test was performed to evaluate the statistical significance of the trend in categorical data over time. Multivariable regression was used to assess the association between vasopressors and preflight massive transfusions, preflight surgical procedures, injury patterns, and age.

RESULTS

We reviewed 147 records of patients transported via CCAT: 68 patients were transported in a regulated fashion and 79 on an unregulated flight. The number of patients evacuated increased year-over-year (n = 22 in 2017, n = 57 in 2018, and n = 68 in 2019, P < .001), and the percentage of missions that were unregulated grew geometrically (14%, n = 3 in 2017; 37%, n = 21 in 2018; and 81%, n = 55 in 2019, P < .001). During the time studied, CCAT teams were being used more to decompress forward surgical teams (FST) and, therefore, they were transporting patients just hours following initial damage control surgery in an unregulated fashion. In 2 instances, CCAT decompressed an FST following a mass casualty, during which aeromedical evacuation (AE) crews assisted with patient care. For the regulated missions, the treatments that were statistically more common were intravenous fluids, propofol, norepinephrine, any vasopressors, and bicarbonate. During unregulated missions, the statistically more common treatments were ketamine, fentanyl, and 3% saline. Additional analysis of the mechanically ventilated patient subgroup revealed that vasopressors were used twice as often on regulated (38%) vs. unregulated (13%) flights. Multivariable regression analysis demonstrated that traumatic brain injury (TBI) was the only significant predictor of in-flight vasopressor use (odds ratio = 3.53, confidence interval [1.22, 10.22], P = .02).

CONCLUSION

During the troop drawdown in Afghanistan, the number of unregulated missions increased geometrically because the medical footprint was decreasing. During unregulated missions, CCAT providers used ketamine more frequently, consistent with Tactical Combat Casualty Care guidelines. In addition, TBI was the only predictor of vasopressor use and may reflect an attempt to adhere to unmonitored TBI clinical guidelines. Interoperability between CCAT and AE teams is critical to meet mass casualty needs in unregulated mission environments and highlights a need for joint training. It remains imperative to evaluate changes in mission requirements to inform en route combat casualty care training.

Blood component resuscitative strategies to mitigate endotheliopathy in a murine hemorrhagic shock model

BACKGROUND

Resuscitation with plasma components has been shown to improve endotheliopathy induced by hemorrhagic shock, but the optimal resuscitation strategy to preserve the endothelial glycocalyx has yet to be defined. The aim of this study was to determine if resuscitation with lactated ringers (LR), whole blood (WB), packed red blood cells (RBC), platelet rich plasma (PRP), platelet poor plasma (PPP), balanced RBC:PRP (1:1), or day 14 RBC (d14) would best minimize endothelial damage following shock.

METHODS

Male C57BL/6 mice were hemorrhaged to a goal mean arterial pressure (MAP) of 25 mm Hg for one hour. Unshocked sham mice served as controls. Mice were then resuscitated with equal volumes of LR, WB, RBC, PRP, PPP, 1:1, or d14 RBC and then sacrificed at 1-, 4-, or 24-hours (n = 5). Serum was analyzed for syndecan-1, ubiquitin C-terminal hydrolase L1 (UCHL-1), and cytokine concentrations. Lungs underwent syndecan-1 immunostaining and lung injury scores were calculated after H&E stains. Proteolytic cleavage of the endothelial glycocalyx was assessed by serum matrix metalloprotease 9 (MMP-9) levels.

RESULTS

Serum syndecan-1 and UCHL-1 levels were significantly increased following resuscitation with d14 RBC compared to other groups. Early elevation in lung syndecan-1 staining was noted in LR treated mice while d14 mice showed decreased staining compared to sham mice following shock. Lung injury scores were significantly elevated 4 hours after resuscitation with LR and d14 RBC compared to WB. Serum MMP-9 levels were significantly increased at 1 and 4-hours in d14 mice compared to sham mice. Systemic inflammation was increased in animals receiving LR, 1:1, or d14 RBC.

CONCLUSION

Resuscitation with WB following hemorrhagic shock reduces endothelial syndecan-1 shedding and mitigates lung injury. Aged RBC and LR fail to attenuate endothelial injury following hemorrhagic shock. Further research will be necessary to determine the effect of each of these resuscitative fluids in a hemorrhagic shock model with the addition of tissue injury.

Storage with ethanol attenuates the red blood cell storage lesion

BACKGROUND

Current management of hemorrhagic shock relies on control of surgical bleeding along with resuscitation with packed red blood cells and plasma in a 1-to-1 ratio. Transfusion, however, is not without consequence as red blood cells develop a series of biochemical and physical changes during storage termed "the red blood cell storage lesion." Previous data has suggested that ethanol may stabilize the red blood cell membrane, resulting in improved deformability. We hypothesized that storage of packed red blood cells with ethanol would alter the red blood cell storage lesion.

METHODS

Mice underwent donation and storage of red blood cells with standard storage conditions in AS-3 alone or ethanol at concentrations of 0.07%, 0.14%, and 0.28%. The red blood cell storage lesion parameters of microvesicles, Band-3, free hemoglobin, annexin V, and erythrocyte osmotic fragility were measured and compared. In additional experiments, the mice underwent hemorrhage and resuscitation with stored packed red blood cells to further evaluate the in vivo inflammatory impact.

RESULTS

Red blood cells stored with ethanol demonstrated decreased microvesicle accumulation and Band-3 levels. There were no differences in phosphatidylserine or cell-free hemoglobin levels. After hemorrhage and resuscitation with packed red blood cells stored with 0.07% ethanol, mice demonstrated decreased serum levels of interleukin-6, macrophage inflammatory protein-1α, keratinocyte chemokine, and tumor necrosis factor α compared to those mice receiving packed red blood cells stored with additive solution-3.

CONCLUSION

Storage of murine red blood cells with low-dose ethanol results in decreased red blood cell storage lesion severity. Resuscitation with packed red blood cells stored with 0.07% ethanol also resulted in a decreased systemic inflammatory response in a murine model of hemorrhage.

MULTIMODAL TREATMENT APPROACHES TO COMBINED TRAUMATIC BRAIN INJURY AND HEMORRHAGIC SHOCK ALTER POSTINJURY INFLAMMATORY RESPONSE

ABSTRACT

Introduction: The optimal management strategies for patients with polytraumatic injuries that include traumatic brain injury (TBI) are not well defined. Specific interventions including tranexamic acid (TXA), propranolol, and hypertonic saline (HTS) have each demonstrated benefits in patient mortality after TBI, but have not been applied to TBI patients with concomitant hemorrhage. The goals of our study were to determine the inflammatory effects of resuscitation strategy using HTS or shed whole blood (WB) and evaluate the cerebral and systemic inflammatory effects of adjunct treatment with TXA and propranolol after combined TBI + hemorrhagic shock. Methods: Mice underwent TBI via weight drop and were subsequently randomized into six experimental groups: three with HTS resuscitation and three with WB resuscitation. Mice were then subjected to controlled hemorrhagic shock for 1 h to a goal MAP of 25 mmHg. Mice were then treated with an i.p. dose of 4 mg/kg propranolol, 100 mg/kg TXA, or normal saline (NS) as a control. Mice were killed at 1, 6, or 24 h for serum and cerebral biomarker evaluation by multiplex ELISA and serum neuron-specific enolase, a biomarker of cerebral cellular injury. Results: Mice resuscitated with HTS had elevated serum proinflammatory cytokines compared with WB resuscitated groups at 6 and 24 h after injury, with no significant difference in cerebral cytokine levels. Within the TBI/shock + HTS groups, the addition of propranolol or TXA did not significantly alter serum cytokine concentration, but cerebral IL-2, IL-12, and macrophage inflammatory protein-1α (MIP-1α) decreased after propranolol administration. In the TBI/shock + WB cohorts, the addition of both propranolol and TXA increased systemic proinflammatory cytokine levels at 6 and 24 h after injury as demonstrated by serum IL-2, IL-12, MIP-1α, and IL-1β compared with NS control. By contrast, TBI/shock + WB mice demonstrated a significant reduction in cerebral IL-2, IL-12, and MIP-1α in propranolol treated mice 6 h after injury compared with NS group. While serum neuron-specific enolase was significantly increased 1 and 24 h after injury in TBI/shock + HTS + TXA cohorts compared with NS control, it was significantly reduced in the TBI/shock + WB + propranolol mice compared with NS control 24 h after injury. Conclusions: Whole blood resuscitation can reduce the acute postinjury neuroinflammatory response after combined TBI/shock compared with HTS. The addition of either propranolol or TXA may modulate the postinjury systemic and cerebral inflammatory response with more improvements noted after propranolol administration. Multimodal treatment with resuscitation and pharmacologic therapy after TBI and hemorrhagic shock may mitigate the inflammatory response to these injuries to improve recovery.

Aspirin Administration Mitigates Platelet Hyperaggregability After Splenectomy in a Murine Model

INTRODUCTION

Patients who undergo splenectomy (SPLN) have an estimated 10%-35% risk of venous thromboembolic events; however, the underlying mechanism and strategy for prevention have yet to be identified. The goals of this study were to 1) investigate platelet aggregation after SPLN, 2) examine if aspirin administration could mitigate this effect, and 3) determine if concomitant hemorrhage would affect post-SPLN platelet function and response to aspirin.

METHODS

Murine models of operative SPLN and submandibular bleed (SMB) were utilized. Mice were randomized to eight groups as follows: untouched, SPLN, sham (laparotomy only), SMB, SPLN + SMB, SPLN + aspirin (ASA), SMB + ASA, and SPLN + SMB + ASA. Aspirin (50 mg/kg) was administered on postoperative days (PODs) one and two via oral gavage. Mice were euthanized on POD 3, platelet counts were obtained, and blood samples were analyzed via rotational thromboelastometry and impedance aggregometry with adenosine diphosphate (ADP) and arachidonic acid (AA) as agonists.

RESULTS

By POD 3, SPLN mice displayed a significant thrombocytosis compared to untouched, SMB, and sham SPLN mice. Clotting time and clot formation time were significantly decreased in SPLN and SPLN + SMB cohorts compared to untouched and sham controls with elevated mean clot firmness. SPLN mice also displayed a significant increase in ADP- and AA-mediated platelet aggregability compared to untouched controls, SMB, and SPLN + SMB. ASA significantly decreased platelet aggregation via both ADP and AA signaling in SPLN and SPLN + SMB cohorts without affecting viscoelastic coagulation testing.

CONCLUSIONS

Platelet hyperaggregability after SPLN is mediated by both ADP and AA signaling. Early aspirin administration may prevent increased platelet aggregation exacerbated after polytrauma.

The Association of Norepinephrine Utilization With Mortality Risk in Trauma Patients

INTRODUCTION

While the pillars of trauma resuscitation are surgical hemostasis and blood product administration, norepinephrine (NE) can be used as an adjunct. The goal of this study was to evaluate the relationship between the maximum dose of NE, timing of NE administration, and mortality in trauma patients.

METHODS

Patients admitted between January 2013 and January 2021 treated with NE were reviewed. Univariate and multivariate logistic regression were used to assess whether maximum NE dose was independently associated with mortality. Optimal dosage rates for NE were determined via Youden Index. Subgroup analyses comparing those who received NE within versus after the first 24 h of admission were conducted.

RESULTS

Three hundred fifty-first trauma patients were included, with 217 (62%) surviving. Patients who died received an average maximum dose of 16.7 mcg/min compared to 9.1 mcg/min in survivors (P = 0.0003). Mortality rate increased with dosage (P < 0.0001), with doses greater than 20 mcg/min having 79% mortality. Those who received NE within the first 24 h had an inflection point in mortality at 16 mcg/min (Youden = 0.45) (OR 1.06; 95% CI 1.03-1.10). For patients who received NE after the first 24 h, an inflection point in mortality was at 10 mcg/min (Youden = 0.34) (OR 1.09; 95% CI 1.04-1.14).

CONCLUSIONS

Higher maximum doses of NE were associated with increased mortality. Patients initiated on NE more than 24 h into their admission displayed an inflection point at a lower dose than those initiated later. This suggests that trauma patients initiated on NE after 24 h from injury may have a dire prognosis.

Effects of antifibrinolytics on systemic and cerebral inflammation after traumatic brain injury

BACKGROUND

Administration of antifibrinolytic medications, including tranexamic acid (TXA), may reduce head injury-related mortality. The effect of these medications on post-traumatic brain injury (TBI) inflammatory response is unknown. The goal of this study was to investigate the role of available antifibrinolytic medications on both systemic and cerebral inflammation after TBI.

METHODS

An established murine weight drop model was used to induce a moderate TBI. Mice were administered 1, 10, or 100 mg/kg of TXA, 400 mg/kg of aminocaproic acid (Amicar, Hospira, Lake Forest, IL), 100 kIU/kg of aprotonin, or equivalent volume of normal saline (NS) 10 minutes after recovery. Mice were euthanized at 1, 6, or 24 hours. Serum and cerebral tissue were analyzed for neuron-specific enolase and inflammatory cytokines. Hippocampal histology was evaluated at 30 days for phosphorylated tau accumulation.

RESULTS

One hour after TBI, mice given TXA displayed decreased cerebral cytokine concentrations of tumor necrosis factor α (TNF-α) and, by 24 hours, displayed decreased concentrations of cerebral TNF-α, interleukin (IL)-6, and monocyte chemoattractant protein 1 compared with TBI-NS. However, serum concentrations of TNF-α and macrophage inflammatory protein 1α (MIP-1α) were significantly elevated from 1 to 24 hours in TBI-TXA groups compared with TBI-NS. The concentration of phosphorylated tau was significantly decreased in a dose-dependent manner in TBI-TXA groups compared with TBI-NS. By contrast, Amicar administration increased cerebral cytokine levels of IL-6 1 hour after TBI, with serum elevations noted in TNF-α, MIP-1α, and monocyte chemoattractant protein 1 at 24 hours compared with TBI-NS. Aprotonin administration increased serum TNF-α, IL-6, and MIP-1α from 1 to 24 hours without differences in cerebral cytokines compared with TBI-NS.

CONCLUSION

Tranexamic acid administration may provide acute neuroinflammatory protection in a dose-dependent manner. Amicar administration may be detrimental after TBI with increased cerebral and systemic inflammatory effects. Aprotonin administration may increase systemic inflammation without significant contributions to neuroinflammation. While no antifibrinolytic medication improved systemic inflammation, these data suggest that TXA may provide the most beneficial inflammatory modulation after TBI.

Defining Endotheliopathy in Murine Polytrauma Models

INTRODUCTION

"Endotheliopathy of trauma" is recognized as endothelial dysfunction following traumatic injury leading to poor patient outcomes. Acute post-traumatic disruptions in endothelial cell function have been associated with profound physiologic, hemodynamic, and coagulation derangements. The goal of this study was to define the generation and extent of endotheliopathy in murine polytrauma models by evaluating the post-traumatic release of serum biomarkers of ongoing cellular injury.

METHODS

Mice were randomized to undergo moderately severe concussive TBI by weight drop, 60-min hemorrhagic shock to MAP 25 mmHg with subsequent resuscitation with Lactated Ringer's, submandibular bleed (SMB), and/or midline laparotomy with rectus muscle crush. Mice were sacrificed at 1, 4, or 24 h for serum biomarker evaluation.

RESULTS

Serum biomarkers revealed differential timing of elevation and injury-dependent release.At 24 h, soluble thrombomodulin was significantly elevated in combined TBI + shock + lap crush compared to untouched, and shock alone. Syndecan-1 levels were significantly elevated after shock 1 to 24 h compared to untouched cohorts with a significant elevation in TBI + shock + lap crush 24 h after injury compared to shock alone. UCHL-1 was significantly elevated in shock mice at 1 to 24 h post-injury compared to untouched mice. UCHL-1 was also significantly elevated in the TBI + shock cohort 24 h after injury compared to shock alone. Hyaluronic acid release at 4 h was significantly elevated in shock alone compared to the untouched cohort with further elevations in TBI + shock + lap crush and TBI + shock compared to shock alone at 24 h. Hyaluronic acid was also increased in lap crush and laparotomy only cohort compared to untouched mice 24 h after injury.

CONCLUSIONS

A murine model of polytrauma including TBI, hemorrhagic shock, and laparotomy abdominal crush is a reliable method for evaluation of endotheliopathy secondary to trauma as indicated by differential changes in serum biomarkers.

Improving packed red blood cell storage with a high-viscosity buffered storage solution

BACKGROUND

Massive transfusion with older packed red blood cells is associated with increased morbidity and mortality. As packed red blood cells age, they undergo biochemical and structural changes known as the storage lesion. We developed a novel solution to increase viscosity in stored packed red blood cells. We hypothesized that packed red blood cell storage in this solution would blunt storage lesion formation and mitigate the inflammatory response after resuscitation.

METHODS

Blood was obtained from 8- to 10-week-old C57BL/6 male donor mice or human volunteers and stored as packed red blood cell units for 14 days for mice or 42 days for humans in either standard AS-3 storage solution or EAS-1587, the novel packed red blood cell storage solution. Packed red blood cells were analyzed for microvesicles, cell-free hemoglobin, phosphatidylserine, band-3 protein, glucose utilization, and osmotic fragility. Additional mice underwent hemorrhage and resuscitation with packed red blood cells stored in either AS-3 or EAS-1587. Serum was analyzed for inflammatory markers.

RESULTS

Murine packed red blood cells stored in EAS-1587 demonstrated reductions in microvesicle and cell-free hemoglobin accumulation as well as preserved band-3 expression, increase glucose utilization, reductions in phosphatidylserine expression, and susceptibility to osmotic stress. Serum from mice resuscitated with packed red blood cells stored in EAS-1587 demonstrated reduced proinflammatory cytokines. Human packed red blood cells demonstrated a reduction in microvesicle and cell-free hemoglobin as well as an increase in glucose utilization.

CONCLUSION

Storage of packed red blood cells in a novel storage solution mitigated many aspects of the red blood cell storage lesion as well as the inflammatory response to resuscitation after hemorrhage. This modified storage solution may lead to improvement of packed red blood cell storage and reduce harm after massive transfusion.

Blood product resuscitation mitigates the effects of aeromedical evacuation after polytrauma

BACKGROUND

The combined injury of traumatic brain injury and hemorrhagic shock has been shown to worsen coagulopathy and systemic inflammation, thereby increasing posttraumatic morbidity and mortality. Aeromedical evacuation to definitive care may exacerbate postinjury morbidity because of the inherent hypobaric hypoxic environment. We hypothesized that blood product resuscitation may mitigate the adverse physiologic effects of postinjury flight.

METHODS

An established porcine model of controlled cortical injury was used to induce traumatic brain injury. Intracerebral monitors were placed to record intracranial pressure, brain tissue oxygenation, and cerebral perfusion. Each of the 42 pigs was hemorrhaged to a goal mean arterial pressure of 40 ± 5 mm Hg for 1 hour. Pigs were grouped according to resuscitation strategy used-Lactated Ringer's (LR) or shed whole blood (WB)-then placed in an altitude chamber for 2 hours at ground, 8,000 ft, or 22,000 ft, and then observed for 4 hours. Hourly blood samples were analyzed for proinflammatory cytokines and lactate. Internal jugular vein blood flow was monitored continuously for microbubble formation with altitude changes.

RESULTS

Cerebral perfusion, tissue oxygenation, and intracranial pressure were unchanged among the six study groups. Venous microbubbles were not observed even with differing altitude or resuscitation strategy. Serum lactate levels from hour 2 of flight to the end of observation were significantly elevated in 22,000 + LR compared with 8,000 + LR and 22,000 + WB. Serum IL-6 levels were significantly elevated in 22,000 + LR compared with 22,000 + WB, 8,000 + LR and ground+LR at hour 1 of observation. Serum tumor necrosis factor-α was significantly elevated at hour 2 of flight in 8,000 + LR versus ground+LR, and in 22,000 + LR vs. 22,000 + WB at hour 1 of observation. Serum IL-1β was significantly elevated hour 1 of flight between 8,000 + LR and ground+LR.

CONCLUSION

Crystalloid resuscitation during aeromedical transport may cause a prolonged lactic acidosis and proinflammatory response that can predispose multiple-injury patients to secondary cellular injury. This physiologic insult may be prevented by using blood product resuscitation strategies.

"Early results after initiation of a rib fixation programme: A propensity score matched analysis"

INTRODUCTION

Chest wall injuries are very common in blunt trauma and development of treatment protocols can significantly improve outcomes. Surgical stabilisation of rib fractures (SSRF) is an adjunct for the most severe chest injuries and can be used as a part of a comprehensive approach to chest injuries care. We hypothesized that implementation of a SSRF programme program would result in improved short-term outcomes.

MATERIALS AND METHODS

The characteristics of the initial group of SSRF patients (Early-SSRF) were used to identify matching factors. Patients prior to SSRF protocol underwent a propensity score match, followed by screening for operative indications and contraindications. After exclusions, a non-operative (Non-Op) cohort was defined (n=36) resulting in an approximately 1:1 match. An overall operative cohort, inclusive of Early-SSRF and all subsequent operative patients, was defined (All- SSRF). A before-and-after analysis using chi-squared, Students T-tests, and Mann-Whitney U-tests were used to assess significance at the level of 0.05.

RESULTS

Early-SSRF (n=22) and All-SSRF (n=45) were compared to Non-Op (n=36). The selection process resulted in well matched groups, and equally well-balanced operative indications between the groups. The Early-SSRF group demonstrated shortened duration of mechanical ventilation and a decreased frequency of being discharged a long-term acute care hospital. The All-SSRF group again demonstrated markedly shorter duration of mechanical ventilation compared to Non-Op (median 6 days vs 16 days, p < 0.01), more decrease discharge to a long-term acute care hospital (9% vs. 36%, p=0.01), and reduced risk for tracheostomy (8.9% vs. 33.3% respectively, p<0.01) CONCLUSION: The introduction of an operative rib fixation to a comprehensive chest wall injury protocol can produce improvements in clinical outcomes that decrease time on the ventilator and tracheostomy rates, and result in more patients being discharged to home. Creation and implementation of a chest wall injury protocol to include SSRF requires a multidisciplinary approach and thoughtful patient selection.

Survival analysis by inflammatory biomarkers in severely injured patients undergoing damage control resuscitation

BACKGROUND

Although early balanced blood product resuscitation has improved mortality after traumatic injury, many patients still suffer from inflammatory complications. The goal of this study was to identify inflammatory mediators associated with death and multiorgan system failure following severe injury after patients undergo blood product resuscitation.

METHODS

A retrospective secondary analysis of inflammatory markers from the Pragmatic Randomized Optimal Platelet and Plasma Ratios study was performed. Twenty-seven serum biomarkers were measured at 8 time points in the first 72 hours of care and were compared between survivors and nonsurvivors. Biomarkers with significant differences were further analyzed by adjudicated cause of 30-day mortality.

RESULTS

Biomarkers from 680 patients were analyzed. Seven key inflammatory markers (IL-1ra, IL-6, IL-8, IL-10, eotaxin, IP-10, and MCP-1) were further analyzed. These cytokines were also noted to have the highest hazard ratios of death. Stepwise selection was used for multivariate analysis of survival by time point. MCP-1 at 2 hours, eotaxin and IP-10 at 12 hours, eotaxin at 24 hours, and IP-10 at 72 hours were associated with all-cause mortality.

CONCLUSION

Early systemic inflammatory markers are associated with increased risk of mortality after traumatic injury. Future studies should use these biomarkers to prospectively calculate risks of morbidity and causes of mortality for all trauma patients.

The Association Between Pulmonary Contusion Severity and Respiratory Failure

BACKGROUND

Pulmonary contusions (PCs) have historically been viewed as a serious complicating factor in thoracic injury. Recently, there has been conflicting evidence regarding the influence of PCs on outcomes; however, many studies do not stratify contusions by severity and may miss clinical associations. We sought to identify if contusion severity is associated with worse outcomes.

METHODS

A previously published chest wall injury database at an urban Level I trauma center was retrospectively reviewed. All severely injured subjects (defined as Injury Severity Score [ISS] ≥ 15) with moderate to severe thoracic injury (defined as a chest wall Abbreviated Injury Scale [AIS] ≥ 3) who required mechanical ventilation for > 24 h were stratified by contusion severity. Moderate to severe contusions were defined as AIS contusion ≥ 3 and Blunt Pulmonary Contusion 18 (BPC18) score ≥ 3.

RESULTS

Over 5 y, 3,836 patients presented with chest wall injuries, of which 1,176 (30.6%) had concomitant contusions. When screened for inclusion criteria, 339 subjects with contusions and 211 subjects without contusions (no-PC) were identified. Of these, 234 had moderate to severe contusions defined by AIS contusion ≥ 3 (PC-A) and 230 had moderate to severe contusions by BPC18 ≥ 3 (PC-B). Compared to no-PC, both PC-A and PC-B groups had significantly lower mortality (17.9% and 17.4%, respectively, vs 28.9%); however, PC-A and PC-B groups had longer durations of mechanical ventilation (6 and 7 d, respectively, vs 5 d), longer ICU length of stay (10 and 10 vs 8 d), and longer overall hospital length of stay (15 and 15 vs 13 d).

CONCLUSIONS

In severely injured polytrauma patients, PCs are seen with more severe chest injuries. Furthermore, moderate to severe contusions are associated with longer durations of mechanical ventilation, ICU length of stay, and hospital length of stay. Despite practice pattern changes, contusions appear to contribute significantly to the clinical course of the blunt chest wall injured patients.

Acute and chronic hematologic implications of emergency and elective splenectomy

INTRODUCTION

Thrombocytosis and leukocytosis are common after splenectomy. The potential effect of emergency surgery on these postoperative findings is unknown. We hypothesized that emergency splenectomy leads to a more profound and persistent hematologic change as compared to elective splenectomy.

METHODS

A retrospective review was conducted of patients who underwent elective or trauma splenectomy. Records were queried for platelet (PLT) and white blood cell (WBC) count prior to splenectomy, on postoperative days 1-5, and at day 14, 1 month, 3 months, 6 months, and 1 year. Complications, including thromboembolic events, infection, need for repeat operation, and readmission within 30 days of discharge, were recorded.

RESULTS

463 patients were identified as being eligible for the study, with 173 patients in the elective cohort and 145 patients in each of the isolated trauma splenectomy and polytrauma cohorts. Both cohorts had peak thrombocytosis at week 2 postoperatively. However, polytrauma patients had a significantly higher peak platelet count (P < 0.01). The PLT:WBC ratio was lower in both trauma cohorts pre-operatively and postoperative day 1. Trauma splenectomy had a higher PLT:WBC ratio on days 2 and 3 whereas polytrauma had a lower ratio on days 4 and 5. Emergency cases had greater reoperation and infection rates, whereas elective cases were more likely to require readmission. Postoperative thromboembolic events were only higher in the polytrauma cohort.

CONCLUSIONS

While trauma splenectomy resulted in more profound postoperative leukocytosis and thrombocytosis, there was no correlation with timing of infection or risk of thromboembolic events. These findings suggest that thrombocytosis and leukocytosis may be associated with thrombotic and infectious events but their presence alone does not indicate direct risks of concomitant infection or thrombosis.

Rhizopus microsporus typhlitis in a patient with acute myelogenous leukemia

While patients undergoing treatment for hematologic malignancies are at risk for a variety of infections, gastrointestinal mucormycosis is a rare and feared complication. Diagnosis requires a high index of suspicion and timely evaluation. Prompt treatment improves patient outcomes.

Hitting the Vasopressor Ceiling: Finding Norepinephrine Associated Mortality in the Critically Ill

BACKGROUND

There is no consensus on what dose of norepinephrine corresponds with futility. The purpose of this study was to investigate the maximum infusion and cumulative doses of norepinephrine associated with survival for patients in medical and surgical intensive care units (MICU and SICU).

MATERIALS AND METHODS

A retrospective review was conducted of 661 critically ill patients admitted to a large academic medical center who received norepinephrine. Univariate, multivariate, and area under the curve analyses with optimal cut offs for maximum infusion rate and cumulative dosage were determined by Youden Index.

RESULTS

The population was 54.9% male, 75.8% white, and 58.7 ± 16.1 y old with 384 (69.8%) admitted to the MICU and 166 (30.2%) admitted to the SICU, including 38 trauma patients. Inflection points in mortality were seen at 18 mcg/min and 17.6 mg. The inflection point was higher in MICU patients at 21 mcg/min and lower in SICU patients at 11 mcg/min. MICU patients also had a higher maximum cumulative dosage of 30.7 mg, compared to 2.7 mg in SICU patients. In trauma patients, norepinephrine infusions up to 5 mcg/min were associated with a 41.7% mortality rate.

CONCLUSION

A maximum rate of 18 mcg/min and cumulative dose of 17.6 mg were the inflection points for mortality risk in ICU patients, with SICU patients tolerating lower doses. In trauma patients, even low doses of norepinephrine were associated with higher mortality. These data suggest that MICU, SICU, and trauma patients differ in need for, response to, and outcome from escalating norepinephrine doses.

Expired But Not Yet Dead: Examining the Red Blood Cell Storage Lesion in Extended-Storage Whole Blood

ABSTRACT

Whole blood is a powerful resuscitation strategy for trauma patients but has a shorter shelf life than other blood products. The red blood cell storage lesion in whole blood has not previously been investigated beyond the standard storage period. In the present study, we hypothesized that erythrocytes in stored whole blood exhibit similar aspects of the red blood cell storage lesion and that transfusion of extended storage whole blood would not result in a more severe inflammatory response after hemorrhage in a murine model. To test this hypothesis, we stored low-titer, O-positive, whole blood units, and packed red blood cells (pRBCs) for up to 42 days, then determined aspects of the red blood cell storage lesion. Compared with standard storage pRBCs, whole blood demonstrated decreased microvesicle and free hemoglobin at 21 days of storage and no differences in osmotic fragility. At 42 days of storage, rotational thromboelastometry demonstrated that clotting time was decreased, alpha angle was increased, and clot formation time and maximum clot firmness similar in whole blood as compared with pRBCs with the addition of fresh frozen plasma. In a murine model, extended storage whole blood demonstrated decreased microvesicle formation, phosphatidylserine, and cell-free hemoglobin. After hemorrhage and resuscitation, TNF-a, IL-6, and IL-10 were decreased in mice resuscitated with whole blood. Red blood cell survival was similar at 24 h after transfusion. Taken together, these data suggest that red blood cells within whole blood stored for an extended period of time demonstrate similar or reduced accumulation of the red blood cell storage lesion as compared with pRBCs. Further examination of extended-storage whole blood is warranted.

Direct Peritoneal Resuscitation Improves Survival in a Murine Model of Combined Hemorrhage and Burn Injury

INTRODUCTION

Combined burn injury and hemorrhagic shock are a common cause of injury in wounded warfighters. Current protocols for resuscitation for isolated burn injury and isolated hemorrhagic shock are well defined, but the optimal strategy for combined injury is not fully established. Direct peritoneal resuscitation (DPR) has been shown to improve survival in rats after hemorrhagic shock, but its role in a combined burn/hemorrhage injury is unknown. We hypothesized that DPR would improve survival in mice subjected to combined burn injury and hemorrhage.

MATERIALS AND METHODS

Male C57/BL6J mice aged 8 weeks were subjected to a 7-second 30% total body surface area scald in a 90°C water bath. Following the scald, mice received DPR with 1.5 mL normal saline or 1.5 mL peritoneal dialysis solution (Delflex). Control mice received no peritoneal solution. Mice underwent a controlled hemorrhage shock via femoral artery cannulation to a systolic blood pressure of 25 mm Hg for 30 minutes. Mice were then resuscitated to a target blood pressure with either lactated Ringer's (LR) or a 1:1 ratio of packed red blood cells (pRBCs) and fresh frozen plasma (FFP). Mice were observed for 24 hours following injury.

RESULTS

Median survival time for mice with no DPR was 1.47 hours in combination with intravascular LR resuscitation and 2.08 hours with 1:1 pRBC:FFP. Median survival time significantly improved with the addition of intraperitoneal normal saline or Delflex. Mice that received DPR followed by 1:1 pRBC:FFP required less intravascular volume than mice that received DPR with LR, pRBC:FFP alone, and LR alone. Intraperitoneal Delflex was associated with higher levels of tumor necrosis factor alpha and macrophage inflammatory protein 1 alpha and lower levels of interleukin 10 and intestinal fatty acid binding protein. Intraperitoneal normal saline resulted in less lung injury 1 hour postresuscitation, but increased to similar severity of Delflex at 4 hours.

CONCLUSIONS

After a combined burn injury and hemorrhage, DPR leads to increased survival in mice. Survival was similar with the use of normal saline or Delflex. DPR with normal saline reduced the inflammatory response seen with Delflex and delayed the progression of acute lung injury. DPR may be a valuable strategy in the treatment of patients with combined burn injury and hemorrhage.

Attending and Resident Surgeon Perspectives and Prescribing Practices of Pain Medication During the Opioid Epidemic

OBJECTIVE

Over 67,000 individuals died in the United States due to drug overdose in 2018; the majority of these deaths were secondary to opioid ingestion. Our aim was to determine surgeon perceptions on opioid abuse, the adequacy of perioperative and graduate medical education, and the role surgeons may play. We also aimed to investigate any differences in attending and resident surgeon attitudes.

DESIGN

Anonymous online survey assessing surgeons' opioid counseling practices, prescribing patterns, and perceptions on opioid abuse, adequacy of education about opioid abuse, and the role physicians play.

SETTING

Two Accreditation Council for Graduate Medical Education accredited general surgery programs at a university-based tertiary hospital and a community hospital in the Midwest.

PARTICIPANTS

Attending and resident physicians within the Departments of Surgery participated anonymously.

RESULTS

Attending surgeons were more likely than residents to discuss posoperative opioids with patients (62% vs. 33%; p < 0.05), discuss the potential of opioid abuse (31% vs. 6%; p < 0.05), and check state-specific prescription monitoring programs (15% vs. 0%; p < 0.05). Surgeons and trainees feel that surgeons have contributed to the opioid epidemic (76% attending vs. 88% resident). Overall, attending and resident surgeons disagree that there is adequate formal education (66% vs. 66%) but adequate informal education (48% vs. 61%) on opioid prescribing. However, when attending physicians were broken down into those who have practiced ≤5 years vs. those with >5 years experience, those with ≤5 years experience were more confident in recognizing opioid abuse (61% vs. 34%) and fewer young faculty disagreed that there is adequate formalized education on opioid prescribing (45% vs. 84%).

CONCLUSION AND RELEVANCE

Patient education should be improved upon in the preoperative setting and should be treated as an important component of preoperative discussions. Formalized opioid education should also be undertaken in graduate surgical education to help guide appropriate opioid use by resident and attending physicians.

Washing packed red blood cells decreases red blood cell storage lesion formation

BACKGROUND

Transfusion of blood products is the ideal resuscitative strategy after hemorrhage. Unfortunately, older packed red blood cells have been associated with increased morbidity and mortality after massive transfusion. These packed red blood cells accumulate biochemical and structural changes known as the red blood cell storage lesions. The effect of washing on the formation of red blood cell storage lesions is unknown. We hypothesized that washing packed red blood cells during storage would decrease the development of the red blood cell storage lesions.

METHODS

Blood from 8- to 10-week-old male mice donors was stored as packed red blood cells for 14 days. A subset of packed red blood cells were washed with phosphate-buffered saline on storage day 7 and resuspended in AS-1 solution for an additional 7 days as washed packed red blood cells. Subsequently, the packed red blood cells were analyzed for microvesicle release, band-3 erythrocyte membrane integrity protein (Band-3), expression of phosphatidylserine, cell viability (calcein), accumulation of cell-free hemoglobin, and osmotic fragility.

RESULTS

In the washed packed red blood cells group, there was less microvesicle accumulation, greater Band-3 expression, less phosphatidylserine expression, a decrease in cell-free hemoglobin accumulation, and a decrease in osmotic fragility, but no differences in red blood cells viability.

CONCLUSION

Washing packed red blood cells during storage decreases the accumulation of red blood cell storage lesions. This strategy may lessen the sequelae associated with transfusion of older packed red blood cells.

Hepatic Pseudoaneurysm Incidence After Liver Trauma

BACKGROUND

Posttraumatic hepatic artery pseudoaneurysm is a potentially devastating complication after complex liver injury. Increasing computed tomography (CT) use may lead to more frequent identification of posttraumatic hepatic complications. This study was designed to determine the rate of hepatic pseudoaneurysm after traumatic liver injury.

METHODS

We conducted a retrospective review of patients at an urban level 1 trauma center over 5 y (2012-2016). Injury characteristics, patient management, and complications were extracted from trauma registry data and chart review.

RESULTS

Six hundred thirty-four hepatic injuries (11 no grade/no CT, 159 grade I, 154 grade II, 165 grade III, 93 grade IV, and 52 grade V) were identified from our trauma registry. No patient with a grade I or II injury had a subsequent bleeding complication. Eighteen patients had a documented hepatic pseudoaneurysm: grade III n = 3 (1.8%), grade IV n = 6 (6.5%), grade V n = 9 (17.3%). The median time to pseudoaneurysm identification was 6.5 d. Seven pseudoaneurysms were found on asymptomatic surveillance CT-angiography on average 5 d after injury. Eleven patients were symptomatic at the time of CT-angiography performed at a median of 9 d after admission. Of the 11 symptomatic patients, four were in hemorrhagic shock, and two died from hepatic-related complications.

CONCLUSIONS

The incidence of hepatic artery pseudoaneurysm increases with higher grade liver injury. Aggressive surveillance for hepatic pseudoaneurysm with interval CT-angiography 5-7 d postinjury may be warranted, especially for grade IV and V injuries.

Effects of Early Altitude Exposure on the Open Abdomen After Laparotomy in Trauma

INTRODUCTION

While damage control surgery and resuscitation techniques have revolutionized the care of injured service members who sustain severe traumatic hemorrhage, the physiologic and inflammatory consequences of hemostatic resuscitation and staged abdominal surgery in the face of early aeromedical evacuation (AE) have not been investigated. We hypothesized that post-injury AE with an open abdomen would have significant physiologic and inflammatory consequences compared to AE with a closed abdomen.

MATERIALS AND METHODS

Evaluation of resuscitation and staged abdominal closure was performed using a murine model of hemorrhagic shock with laparotomy. Mice underwent controlled hemorrhage to a systolic blood pressure of 25 mmHg and received either no resuscitation, blood product resuscitation, or Hextend resuscitation to a systolic blood pressure of either 50 mmHg (partial resuscitation) or 80 mmHg (complete resuscitation). Laparotomies were either closed prior to AE (closed abdomens) or left open during AE (open abdomens) and subsequently closed. AE was simulated with a 1-hour exposure to a hypobaric hypoxic environment at 8,000 feet altitude. Mice were euthanized at 0, 4, or 24 hours following AE. Serum was collected and analyzed for physiologic variables and inflammatory cytokine levels. Samples of lung and small intestine were collected for tissue cytokine and myeloperoxidase analysis as indicators of intestinal inflammation. Survival curves were also performed.

RESULTS

Unresuscitated mice sustained an 85% mortality rate from hemorrhage and laparotomy, limiting the assessment of the effect of simulated AE in these subgroups. Overall survival was similar among all resuscitated groups regardless of the presence of hypobaric hypoxia, type of resuscitation, or abdominal closure status. Simulated AE had no observed effects on acid/base imbalance or the inflammatory response as compared to ground level controls. All mice experienced both metabolic acidosis and an acute inflammatory response after hemorrhage and injury, represented by an initial increase in serum interleukin (IL)-6 levels. Furthermore, mice with open abdomens had an elevated inflammatory response with increased levels of serum IL-10, serum tumor necrosis factor alpha, intestinal IL-6, intestinal IL-10, and pulmonary myeloperoxidase.

CONCLUSION

These results demonstrate the complex interaction of AE and temporary or definitive abdominal closure after post-injury laparotomy. Contrary to our hypothesis, we found that AE in those animals with open abdomens is relatively safe with no difference in mortality compared to those with closed abdomens. However, given the physiologic and inflammatory changes observed in animals with open abdomens, further evaluation is necessary prior to definitive recommendations regarding the safety or downstream effects of exposure to AE prior to definitive abdominal closure.

Innate coagulability changes with age in stored packed red blood cells

BACKGROUND

Packed red blood cell (pRBC) units administered during resuscitation from hemorrhagic shock are of varied storage ages. We have previously shown that RBC-derived microparticles' impact on thrombogenesis. However, the impact of storage age on pRBC coagulability is unknown. Therefore, we sought to investigate the effect of storage age on innate coagulability and aggregability of stored pRBCs.

METHODS

pRBCs prepared from male C57BL/6J mice were stored in Additive Solution-3 according to our standardized murine blood banking protocols for 14 days. Rotational thromboelastometry (ROTEM) was used to assess the innate coagulation status of fresh and 14-day old pRBCs. Viscoelastic coagulation parameters of clotting time (CT), clot formation time (CFT), alpha angle, and maximum clot firmness (MCF) were analyzed to determine coagulability. Plasma was added to the fresh pRBCs and 15-day old pRBCs to determine if the storage-associated coagulopathy was reversible with plasma. Statistical analyses were conducted with a Student's t-test.

RESULTS

Fifteen-day old pRBCs demonstrated a significant reduction in MCF (10.3 vs. 24.4 mm, P-value <0.001) and alpha angle (6.0 vs. 27.2 degrees, P-value <0.001) as well as significant prolongation of CFT and CT (1126.5 vs. 571.4 s, P-value <0.001) compared to fresh pRBCs. FFP addition to 15-day old and fresh pRBCs, demonstrated a significant reduction in MCF and persistent prolongation of CFT. This suggests that pRBCs lost coagulability as they aged and this deficit was not completely corrected by plasma administration.

CONCLUSIONS

Storage duration may be an important factor in coagulation potential of pRBCs. Transfusion with older pRBCs may contribute to coagulopathy in massively transfused patients.

Characterizing Early Inpatient Death After Trauma

BACKGROUND

There is a paucity of data to predict early death or futility after trauma. The objective of this study was to characterize the laboratory values, blood product administration, and hospital disposition for patients with trauma who died within 72 h of admission.

METHODS

All deaths within 72 h of admission over a 5-y period at a level I trauma center were reviewed. Blood transfusion within the first 4 h of arrival and patient disposition from the emergency department to the operating room (OR), surgical intensive care unit, or the neuroscience intensive care unit (NSICU) were analyzed. Kaplan-Meier curves were generated to determine time to death.

RESULTS

A total of 622 subjects were identified; 39.5% died in the emergency department, 10.6% went directly to the OR, 13.6% were admitted to the surgical intensive care unit, and 29.7% admitted to the NSICU. Of these subjects, 201 (32.2%) patients received blood within the first 4 h. By 24 h, early blood transfusion was associated with more rapid death for patients who were admitted to the NSICU (80% versus 60% mortality, P = 0.01) but not for patients taken directly to the OR (80% versus 70% mortality, P = 0.2). Admission coagulopathy by international normalized ratio (P < 0.01), but not anemia (P = 0.64) or acidosis (P = 0.45), correlated with a shorter time to death. In contrast, laboratory values obtained at 4 h after admission did not correlate with time to death.

CONCLUSIONS

Our data demonstrate that admission coagulation derangement and need for early blood product transfusion are the two factors most associated with early death after injury, particularly in those patients with traumatic brain injury. These data will help construct future models for futility of continued care in patients with trauma.

Development of Optimized Tissue-Factor-Targeted Peptide Amphiphile Nanofibers to Slow Noncompressible Torso Hemorrhage

Noncompressible torso hemorrhage accounts for a significant portion of preventable trauma deaths. We report here on the development of injectable, targeted supramolecular nanotherapeutics based on peptide amphiphile (PA) molecules that are designed to target tissue factor (TF) and, therefore, selectively localize to sites of injury to slow hemorrhage. Eight TF-targeting sequences were identified, synthesized into PA molecules, coassembled with nontargeted backbone PA at various weight percentages, and characterized via circular dichroism spectroscopy, transmission electron microscopy, and X-ray scattering. Following intravenous injection in a rat liver hemorrhage model, two of these PA nanofiber coassemblies exhibited the most specific localization to the site of injury compared to controls (p < 0.05), as quantified using immunofluorescence imaging of injured liver and uninjured organs. To determine if the nanofibers were targeting TF in vivo, a mouse saphenous vein laser injury model was performed and showed that TF-targeted nanofibers colocalized with fibrin, demonstrating increased levels of nanofiber at TF-rich sites. Thromboelastograms obtained using samples of heparinized rat whole blood containing TF demonstrated that no clots were formed in the absence of TF-targeted nanofibers. Lastly, both PA nanofiber coassemblies decreased blood loss in comparison to sham and backbone nanofiber controls by 35-59% (p < 0.05). These data demonstrate an optimal TF-targeted nanofiber that localizes selectively to sites of injury and TF exposure, and, interestingly, reduces blood loss. This research represents a promising initial phase in the development of a TF-targeted injectable therapeutic to reduce preventable deaths from hemorrhage.

Death by Decade: Establishing a Transfusion Ceiling for Futility in Massive Transfusion

BACKGROUND

Age and massive transfusion are predictors of mortality after trauma. We hypothesized that increasing age and high-volume transfusion would result in progressively elevated mortality rates and that a transfusion "ceiling" would define futility.

METHODS

The Trauma Quality Improvement Program (TQIP) database was queried for 2013-2016 records and our level I trauma registry was reviewed from 2013 to 2018. Demographic, mortality, and blood transfusion data were collected. Patients were grouped by decade of life and by packed red blood cell (pRBC) transfusion requirement (zero units, 1-3 units, or ≥4 units) within 4 h of admission.

RESULTS

TQIP analysis demonstrated an in-hospital mortality risk that increased linearly with age, to an odds ratio of 10.1 in ≥80 y old (P < 0.01). Mortality rates were significantly higher in older adults (P < 0.01) and those with more pRBCs transfused. In massively transfused patients, the transfusion "ceiling" was dependent on age. Owing to the lack granularity in the TQIP database, 230 patients from our institution who received ≥4 units of pRBCs within 4 h of admission were reviewed. On arrival, younger patients had significantly higher heart rates and more severe derangements in lactate levels, base deficits, and pH compared with older patients. There were no differences among age groups in injury severity score, systolic blood pressure, or mortality.

CONCLUSIONS

In massively transfused patients, mortality increased with age. However, a significant proportion of older adults were successfully resuscitated. Therefore, age alone should not be considered a contraindication to high-volume transfusion. Traditional physiologic and laboratory criteria indicative of hemorrhagic shock may have reduced reliability with increasing age, and thus providers must have a heightened suspicion for hemorrhage in the elderly. Early transfusion requirements can be combined with age to establish prognosis to define futility to help counsel families regarding mortality after traumatic injury.

Emerging Therapies for Prehospital Control of Hemorrhage

BACKGROUND

The aim of this review was to describe emerging therapies that could serve as a prehospital intervention to slow or stop noncompressible torso hemorrhage in the civilian and military settings. Hemorrhage accounts for 90% of potentially survivable military deaths and 30%-40% of trauma deaths. There is a great need to develop novel therapies to slow or stop noncompressible torso hemorrhage at the scene of the injury.

METHODS

A comprehensive literature search was performed using PubMed (1966 to present) for therapies not approved by the Food and Drug Administration for noncompressible torso hemorrhage in the prehospital setting. Therapies were divided into compressive versus intravascular injectable therapies. Ease of administration, skill required to use the therapy, safety profile, stability, shelf-life, mortality benefit, and efficacy were reviewed.

RESULTS

Multiple potential therapies for noncompressible torso hemorrhage are currently under active investigation. These include (1) tamponade therapies, such as gas insufflation and polyurethane foam injection; (2) freeze-dried blood products and alternatives such as lyophilized platelets; (3) nanoscale injectable therapies such as polyethylene glycol nanospheres, polyethylenimine nanoparticles, SynthoPlate, and tissue factor-targeted nanofibers; and (4) other injectable therapies such as polySTAT and adenosine, lidocaine, and magnesium. Although each of these therapies shows great promise at slowing or stopping hemorrhage in animal models of noncompressible hemorrhage, further research is needed to ensure safety and efficacy in humans.

CONCLUSIONS

Multiple novel therapies are currently under active investigation to slow or stop noncompressible torso hemorrhage in the prehospital setting and show promising results.

IFNγ and TNFα mediate CCL22/MDC production in alveolar macrophages after hemorrhage and resuscitation

Acute lung injury is a major complication of hemorrhagic shock and the required resuscitation with large volumes of crystalloid fluids and blood products. We previously identified a role of macrophage-derived chemokine (CCL22/MDC) pulmonary inflammation following hemorrhage and resuscitation. However, further details regarding the induction of CCL22/MDC and its precise role in pulmonary inflammation after trauma remain unknown. In the current study we used in vitro experiments with a murine alveolar macrophage cell line, as well as an in vivo mouse model of hemorrhage and resuscitation, to identify key regulators in CCL22/MDC production. We show that trauma induces expression of IFNγ, which leads to production of CCL22/MDC through a signaling mechanism involving p38 MAPK, NF-κB, JAK, and STAT-1. IFNγ also activates TNFα production by alveolar macrophages, potentiating CCL22/MDC production via an autocrine mechanism. Neutralization of IFNγ or TNFα with specific antibodies reduced histological signs of pulmonary injury after hemorrhage and reduced inflammatory cell infiltration into the lungs.

Evaluation of a Novel Fibrin Sealant Patch in Hemorrhage Control After Vascular or Hepatic Injury

INTRODUCTION

Acute hemorrhage remains the leading cause of death in potentially survivable injuries. The use of topical hemostatic agents has increased over the last two decades with the evolution of damage control surgery. By 2008, the military widely adopted Combat Gauze as the hemostatic dressing of choice for compressible hemorrhage. The goal of this study was to compare the performance of a novel fibrin sealant patch to Combat Gauze in two clinically relevant models of hemorrhage.

MATERIALS AND METHODS

Yorkshire swine underwent unilateral femoral artery puncture or a grade V liver laceration with timed free bleeding then received either the fibrin patch or Combat Gauze packing with 3 minutes of standardized pressure. Animals were then resuscitated to maintain a mean arterial pressure of 60 mmHg for 4 hours. Hemostasis, blood loss, resuscitation volume, survival, vessel patency, and hematologic parameters were evaluated.

RESULTS

Hemostasis was equivalent in both groups after hepatic and vascular injury. Survival was 80% in the fibrin patch vascular injury group and 100% in all other groups. Hematologic parameters were not significantly different between treatment groups. Femoral artery patency was 80% in both groups after vascular injury. With simulated ambulation after vessel injury, 60% of the Combat Gauze group and 80% of the fibrin patch group remained hemostatic (p > 0.05). In simulated re-exploration with packing removal, all animals rebled after hemostatic product removal.

CONCLUSION

There was no significant difference in hemostasis between a novel fibrin patch and Combat Gauze after extremity arterial or hepatic injury. This novel fibrin patch may have a clinical advantage over the Combat Gauze, as it can be left in the body, thereby limiting the potential need for reoperation.

Microparticles from aged packed red blood cell units stimulate pulmonary microthrombus formation via P-selectin

INTRODUCTION

During storage, packed red blood cells undergo a series of physical, metabolic, and chemical changes collectively known as the red blood cell storage lesion. One key component of the red blood cell storage lesion is the accumulation of microparticles, which are submicron vesicles shed from erythrocytes as part of the aging process. Previous studies from our laboratory indicate that transfusion of these microparticles leads to lung injury, but the mechanism underlying this process is unknown. In the present study, we hypothesized that microparticles from aged packed red blood cell units induce pulmonary thrombosis.

MATERIALS AND METHODS

Leukoreduced, platelet-depleted, murine packed red blood cells (pRBCS) were prepared then stored for up to 14 days. Microparticles were isolated from stored units via high-speed centrifugation. Mice were transfused with microparticles. The presence of pulmonary microthrombi was determined with light microscopy, Martius Scarlet Blue, and thrombocyte stains. In additional studies microparticles were labelled with CFSE prior to injection. Murine lung endothelial cells were cultured and P-selectin concentrations determined by ELISA. In subsequent studies, P-selectin was inhibited by PSI-697 injection prior to transfusion.

RESULTS

We observed an increase in microthrombi formation in lung vasculature in mice receiving microparticles from stored packed red blood cell units as compared with controls. These microthrombi contained platelets, fibrin, and microparticles. Treatment of cultured lung endothelial cells with microparticles led to increased P-selectin in the media. Treatment of mice with a P-selectin inhibitor prior to microparticle infusion decreased microthrombi formation.

CONCLUSIONS

These data suggest that microparticles isolated from aged packed red blood cell units promote the development of pulmonary microthrombi in a murine model of transfusion. This pro-thrombotic event appears to be mediated by P-selectin.

Early Identification of Acute Lung Injury in a Porcine Model of Hemorrhagic Shock

BACKGROUND

Acute lung injury (ALI) is a frequent complication after severe trauma. Lung-protective ventilation strategies and damage control resuscitation have been proposed for the prevention of ALI; however, there are no clinical or laboratory parameters to predict who is at risk of developing ALI after trauma. In the present study, we explored pulmonary inflammatory markers as a potential predictor of ALI using a porcine model of hemorrhagic shock.

MATERIALS AND METHODS

Female swine were randomized to mechanical ventilation with low tidal volume (V_T) (6 mL/kg) or high V_T (12 mL/kg). After equilibration, animals underwent pressure-controlled hemorrhage (mean arterial pressure [MAP] 35 ± 5 mmHg) for 1 h, followed by resuscitation with fresh whole blood or Hextend. They were maintained at MAP of 50 ± 5 mmHg for 3 h in the postresuscitation phase. Bronchoalveolar lavage fluids were collected hourly and analyzed for inflammatory markers. Lung samples were taken, and porcine neutrophil antibody staining was used to evaluate the presence of neutrophils. ELISA evaluated serum porcine surfactant protein D levels. Sham animals were used as negative controls.

RESULTS

Pigs that underwent hemorrhagic shock had higher heart rates, lower cardiac output, lower MAPs, and worse acidosis compared with sham at the early time points (P < 0.05 each). There were no significant differences in central venous pressure or pulmonary capillary wedge pressure between groups. Pulmonary neutrophil infiltration, as defined by neutrophil antibody staining on lung samples, was greater in the shock groups regardless of resuscitation fluid (P < 0.05 each). Bronchoalveolar lavage fluid neutrophil levels were not different between groups. There were no differences in levels of porcine surfactant protein D between groups at any time points, and the levels did not change over time in each respective group.

CONCLUSIONS

Our study demonstrates the reproducibility of a porcine model of hemorrhagic shock that is consistent with physiologic changes in humans in hemorrhagic shock. Pulmonary neutrophil infiltration may serve as an early marker for ALI; however, the practicality of this finding has yet to be determined.

Relationship of Coagulopathy and Platelet Dysfunction to Transfusion Needs After Traumatic Brain Injury

BACKGROUND

Coagulopathy and platelet dysfunction commonly develop after traumatic brain injury (TBI). Thromboelastography (TEG) and platelet function assays (PFAs) are often performed at the time of admission; however, their roles in assessing post-TBI coagulopathy have not been investigated. We hypothesized that compared to blunt TBI, penetrating TBI would (1) demonstrate greater coagulopathy by TEG, (2) be associated with abnormal PFA results, and (3) require more blood product transfusions.

METHODS

We performed a retrospective study of patients admitted to the neuroscience intensive care unit of a level 1 trauma center from 2013 to 2015 with head Abbreviated Injury Scale ≥3. Patients were compared by mechanism of injury (blunt vs. penetrating). Admission demographics, injury characteristics, and laboratory parameters were evaluated. VerifyNow^® Aspirin and P2Y12 tests were used for platelet function analysis.

RESULTS

Five hundred and thirty-four patients were included in the analysis. There were no differences between groups in platelet count or international normalized ratio; however, patients with penetrating TBI were more coagulopathic by TEG, with all of the TEG parameters being significantly different except for R time. Patients with penetrating head trauma were not more likely than their blunt counterparts to have abnormal PFA results, and PFA results did not correlate with any TEG parameter in either group. The penetrating cohort received more units of blood products in the first 4 and 24 h than the blunt cohort.

CONCLUSIONS

Patients presenting with penetrating TBI demonstrated increased coagulopathy compared to those with blunt TBI as measured by TEG and need for transfusion. PFA results did not correlate with TEG findings in this population.

Non-Invasive Ventilatory Support In the Elderly

PURPOSE OF REVIEW

The first description of non-invasive ventilation use began in the 1920s. Since then, its role in patient care has evolved through increased clinical knowledge and scientific advancements. The utilization of non-invasive ventilation has broadened from initial application in acute in-hospital ICU settings to now include the outpatient settings. This review discusses the history of non-invasive ventilation and its role in acute in-hospital chronic obstructive pulmonary disease (COPD) exacerbations, cardiogenic pulmonary edema, and weaning from mechanical ventilation in the elderly. The elderly population represents a significant portion of patients hospitalized for the aforementioned conditions. These groups often have more limitations related to the use of invasive mechanical ventilation (IMV), therefore, it is essential to understand the impact of non-invasive ventilation on hospital outcomes.

RECENT FINDINGS

There is strong clinical evidence supporting the use of non-invasive ventilation in patients with respiratory failure secondary to acute COPD exacerbations and cardiogenic pulmonary edema. When compared to standard medical management of these conditions, there is a consistent and significant reduction in the rate of endotracheal intubation and in-hospital mortality.

SUMMARY

The basis of noninvasive ventilation applicability has been determined by significant reduction in mortality and intubation rates. Although survival benefits have been observed, there still remain limitations to the clinical applicability of non-invasive ventilation in certain patient populations and conditions that require further investigation.

Effects of whole blood leukoreduction on platelet function and hemostatic parameters

AIMS/OBJECTIVES

The aim of this study was to evaluate the hemostatic consequences of whole blood leukoreduction (LR).

BACKGROUND

Whole blood is being used for trauma resuscitation in the military, and an increasing number of civilian trauma centres across the nation. The benefits of LR, such as decreased infectious and transfusion-related complications, are well established, but the effects on hemostatic parameters remain a concern.

METHODS

Twenty-four units of whole blood were assigned to one of the four groups: non-leukoreduced (NLR), leukoreduced at 1 h and a height of 33 in. (LR-1), leukoreduced at 4 h and a height of 33 in. (LR-4(33)), or leukoreduced at 4 h and a height of 28 in. (LR-4(28)). Viscoelastic parameters, platelet aggregation, cell counts, physiological parameters and thrombin potential were evaluated immediately before and after LR, and on days 1, 7, 14 and 21 following LR.

RESULTS

The viscoelastic parameters and thrombin generation potential were unchanged between the groups. Platelet aggregation was reduced in the LR-1 group compared with NLR after 7 days. The LR-4(28) group also showed a trend of reduced platelet aggregation compared with NLR. Aggregation in LR-4(33) was similar to NLR throughout the storage time. Physiological and electrolyte changes over the whole blood storage period were not affected by LR.

CONCLUSION

Our study shows that whole blood can be LR at 4 h after collection and a height of 33 in. while maintaining platelet count and without altering platelet function and hemostatic performance.

UCH-L1 is a Poor Serum Biomarker of Murine Traumatic Brain Injury After Polytrauma

BACKGROUND

Several serum biomarkers have been studied to diagnose incidence and severity of traumatic brain injury (TBI), but a reliable biomarker in TBI has yet to be identified. Ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) has been proposed as a biomarker in clinical and preclinical studies, largely in the setting of isolated TBI or concussion. The aim of this study was to evaluate the performance of UCH-L1 as a serum biomarker in the setting of polytrauma and TBI.

METHODS

Multiple variations of murine TBI and polytrauma models were used to evaluate serum biomarkers. The different models included TBI with and without hemorrhagic shock and resuscitation, isolated extremity vascular ligation, extremity ischemia/reperfusion, and blunt tail injury. Blood was drawn at intervals after injury, and serum levels of neuron-specific enolase, UCH-L1, creatine kinase, and syndecan-1 were evaluated by enzyme-linked immunosorbent assay.

RESULTS

UCH-L1 levels were not significantly different between TBI, tail injury, and sham TBI. By contrast, neuron-specific enolase levels were increased in TBI mice compared with tail injury and sham TBI mice. UCH-L1 levels increased regardless of TBI status at 30 min and 4 h after hemorrhagic shock and resuscitation. In mice that underwent femoral artery cannulation followed by hemorrhagic shock/resuscitation, UCH-L1 levels were significantly elevated compared with shock sham mice at 4 h (3158 ± 2168 pg/mL, 4 h shock versus 0 ± 0 pg/mL, 4 h shock sham; P < 0.01) and at 24 h (3253 ± 2954 pg/mL, 24 h shock versus 324 ± 482 pg/mL, 24 h shock sham; P = 0.03). No differences were observed in UCH-L1 levels between the sham shock and the arterial ligation, vein ligation, or extremity ischemia/reperfusion groups at any time point. Similar to UCH-L1, creatine kinase was elevated only after shock compared with sham mice at 4, 24, and 72 h after injury.

CONCLUSIONS

Our study demonstrates that UCH-L1 is not a specific marker for TBI but is elevated in models that induce central and peripheral nerve ischemia. Given the increase in UCH-L1 levels observed after hemorrhagic shock, we propose that UCH-L1 may be a useful adjunct in quantifying severity of shock or global ischemia rather than as a specific marker of TBI.