Succinate metabolism and membrane reorganization drives the endotheliopathy and coagulopathy of traumatic hemorrhage.

Acute hemorrhage commonly leads to coagulopathy and organ dysfunction or failure. Recent evidence suggests that damage to the endothelial glycocalyx contributes to these adverse outcomes. The physiological events mediating acute glycocalyx shedding are undefined, however. Here, we show that succinate accumulation within endothelial cells drives glycocalyx degradation through a membrane reorganization-mediated mechanism. We investigated this mechanism in a cultured endothelial cell hypoxia-reoxygenation model, in a rat model of hemorrhage, and in trauma patient plasma samples. We found that succinate metabolism by succinate dehydrogenase mediates glycocalyx damage through lipid oxidation and phospholipase A2-mediated membrane reorganization, promoting the interaction of matrix metalloproteinase 24 (MMP24) and MMP25 with glycocalyx constituents. In a rat hemorrhage model, inhibiting succinate metabolism or membrane reorganization prevented glycocalyx damage and coagulopathy. In patients with trauma, succinate levels were associated with glycocalyx damage and the development of coagulopathy, and the interaction of MMP24 and syndecan-1 was elevated compared to healthy controls.

Prehospital Simple Thoracostomy Does Not Improve Patient Outcomes Compared to Needle Thoracostomy in Severely Injured Trauma Patients.

BACKGROUND: ATLS suggests simple thoracostomy (ST) after failure of needle thoracostomy (NT) in thoracic trauma. Some EMS agencies have adopted ST into their practice. We sought to describe our experience implementing ST in the prehospital setting, hypothesizing that prehospital ST would reduce failure rates and improve outcomes compared to NT. METHODS: This was a retrospective review of adult trauma patients who received prehospital ST or NT from 2017 to 2020. RESULTS: There were 48 patients with 64 procedures included. 83.7% were male and 65.8% injured by penetrating mechanism and of median (IQR) age of 31 (25-46) years. 28 (43.8%) procedures were NT and 36 (56.3%) were ST. Rates of improved patient response (P = .15), noted return of blood/air (P = .19), and return of spontaneous circulation (P = .62) did not differ. On-scene times were higher for ST (16.8 vs 11.5 minutes; P < .02). Overall mortality did not differ between ST and NT (68.2% vs 46.4%, respectively; P = .125). For patients that survived beyond the ED, procedure-related complication rates were 2 of 21 patients (9.5%) in ST and 1 of 12 (8.3%) in NT. In penetrating trauma, simple thoracostomy had longer on-scene time and total prehospital time. DISCUSSION: ST did not improve success rates of ROSC and was associated with prolonged prehospital times, especially in penetrating trauma patients. Given the benefit of "scoop and run" in urban penetrating trauma, consideration should be given to direct transport in lieu of ST. Use of ST in blunt trauma should be evaluated prospectively.

Plastic recovery and self-healing in longitudinally twinned SiGe nanowires.

This paper reports on plastic recovery and self-healing behavior in longitudinally-twinned and [112] orientated SiGe nanowire (NW) beams when they are subjected to large bending strains. The NW alloys are comprised of lamellar nanotwin platelet(s) sandwiched between two semi-cylindrical twins. The loading curves, which are acquired from atomic force microscope (AFM) based three-point bending tests, reveal the onset of plastic deformation at a characteristic stress threshold, followed by further straining of the NWs. This ductility is attributed to dislocation activity within the semi-cylindrical crystal portions of the NW, which are hypothesized to undergo a combination of elastic and plastic straining. On the other hand, the lamellar nanoplatelets undergo purely elastic stretching. During the unloading process, the release of internal elastic stresses enables dislocation backflow and escape at the surface. As a result, the dislocations are predominantly annihilated and the NW samples evidenced self-healing via plastic recovery even at ultra-large strains, which are estimated using finite-element models at 16.3% in one of the tested devices. Finite element analysis also establishes the independence of the observed nanomechanical behavior on the relative orientation of the load with respect to the nanoplatelet. This first observation of reversible plasticity in the SiGe material system, which is aided by a concurrent evolution of segmented elastic and plastic deformation within its grains during the loading process, presents an important new pathway for mechanical stabilization of technologically important group-IV semiconductor nanomaterials.

Cost Burden and Mortality in Rural Emergency General Surgery Transfer Patients.

BACKGROUND: Recent articles have suggested regionalization of some emergency general surgery (EGS) problems to tertiary referral centers. We sought to characterize the clinical and cost burden of such transfers to our tertiary referral center. MATERIALS AND METHODS: Data were collected retrospectively for nine EGS diagnoses for patients admitted to the EGS service during calendar years 2015 and 2016. Patients were grouped as inpatient transfers (IPTs), Emergency Department transfers (EDTs), or local admissions (LAs). Demographic data, length of stay at originating site, insurance status, Charlson Comorbidity Index, and all relevant financial data were obtained. RESULTS: Six hundred sixty-three patients were reviewed: 93 IPTs, 343 EDTs, and 227 LAs. IPTs required longer lengths of stay (7.0 d compared to 4.0 d for EDTs and 3.0 d for LAs), higher median direct costs, and higher case mix index, which produced a higher median revenue but averaged a median net loss (-$264 compared to +$2436 for EDTs and +$3125 for LAs). The IPTs had higher median comorbidities (Charlson Comorbidity Index 3.5 versus 2.9 for EDTs and 2.0 for LAs), age (62 y versus 58 for EDTs and 52 for LAs), and mortality rate (7.5% versus 2.3% for EDTs and 0.4% for LAs). CONCLUSIONS: Patients who present to a tertiary care EGS service as an IPT from another hospital have more comorbidities, higher mortality rate, and result in a financial loss. These data suggest the need for adequate risk adjustment in quality assessment of tertiary referral center outcomes and the need for increased financial reimbursement for the care of these patients.

Experience with uncrossmatched blood refrigerator in emergency department.

BACKGROUND: Uncrossmatched packed red blood cell (PRBC) transfusion is fundamental in resuscitation of hemorrhagic shock. Ready availability of uncrossmatched blood can be achieved by storing uncrossmatched blood in a blood bank refrigerator in the emergency department (ED), but could theoretically lead to inappropriate uncrossmatched use. METHODS: This retrospective study was performed at a level I trauma center from January 2013 to March 2014. Possibly inappropriate transfusion was defined as patients who received at least one unit of blood from the ED refrigerator and no more than two units of PRBC in the first 24 hours. Deaths within the first 24 hours were excluded. Patients who received blood from the ED refrigerator who received ≤2 units total in 24 hours were compared with those who received >2 units. RESULTS: 158 adults received blood from the ED refrigerator. 140 (88.6%) were trauma patients. 37 (23.4%) received massive transfusion (MT). 42 (26.6%) deaths were excluded. 29 patients received ≤2 units and 87 received >2 units in the first 24 hours. The ≤2 units group had a higher systolic blood pressure (116 mm Hg vs. 102 mm Hg, p=0.042), lower base deficit (6.4 mEq/L vs. 9.4 mEq/L, p=0.032), higher hematocrit (34% vs. 30%, p=0.024), lower rate of MT protocol activation (27.6% vs. 58.6%, p=0.005), and lower rates of transfusion of fresh frozen plasma (17.2% vs. 54.0%, p=0.001) and platelets (13.8% vs. 39.1%, p=0.012). Appropriately transfused patients were more likely to have evidence of shock with active, non-compressible hemorrhage. Potentially inappropriate uses were more likely in patients either without evidence of hemorrhage or without signs of shock. DISCUSSION: Storing uncrossmatched blood in the ED is an effective way to get PRBCs transfused quickly in hemorrhaging patients and is associated with a low rate of unnecessary uncrossmatched transfusion. Provider education and good clinical judgment are imperative to prevent unnecessary use. LEVEL OF EVIDENCE: Level III, therapeutic.

Use of Plasma-Based Trauma Transfusion Protocols at Level IV Trauma Centers.

Early initiation of a high ratio massive transfusion can lower trauma patient mortality by 80%. Long transport times from rural Level IV trauma centers therefore require that damage control resuscitation begin before patient transfer. This study evaluates the current use of fresh frozen plasma (FFP) at Level IV trauma centers and the feasibility of implementing trauma transfusion protocols at these centers. Demographic and clinical data were collected for trauma patients at all state Level IV trauma centers who would have met criteria for massive transfusion protocol (MTP) activation based on the Assessment of Blood Consumption (ABC) score. All state Level IV trauma centers were also surveyed to determine availability of blood bank plasma resources. A total of 760 adult trauma patients presented to a Level IV trauma center during the study period. Three hundred sixty-eight patients (48.4%) were transferred to a higher level of care. Because FAST (Focused Assessment with Sonography for Trauma) results were not available in the state registry data, we included all blunt trauma patients with an ABC score of 1 as "potential ABC-positive patients." Forty-two (5.5%) patients were potentially ABC positive. Fifteen of 22 Level IV centers responded to our survey. Seventy-three percent of respondents have FFP available. Mean time to FFP availability was 63.1 min. Median total length of stay from registration to emergency department discharge for potentially ABC-positive patients was 2 hr. Because most Level IV trauma centers have FFP and thaw times are such that administration would not delay transport to a higher level of care, we recommend implementation of MTPs at Level IV trauma centers to reduce hemorrhage-associated mortality.

Phase Boundary Propagation in Li-Alloying Battery Electrodes Revealed by Liquid-Cell Transmission Electron Microscopy.

Battery cycle life is directly influenced by the microstructural changes occurring in the electrodes during charge and discharge cycles. Here, we image in situ the nanoscale phase evolution in negative electrode materials for Li-ion batteries using a fully enclosed liquid cell in a transmission electron microscope (TEM) to reveal early degradation that is not evident in the charge-discharge curves. To compare the electrochemical phase transformation behavior between three model materials, thin films of amorphous Si, crystalline Al, and crystalline Au were lithiated and delithiated at controlled rates while immersed in a commercial liquid electrolyte. This method allowed for the direct observation of lithiation mechanisms in nanoscale negative electrodes, revealing that a simplistic model of a surface-to-interior lithiation front is insufficient. For the crystalline films, a lithiation front spread laterally from a few initial nucleation points, with continued grain nucleation along the growing interface. The intermediate lithiated phases were identified using electron diffraction, and high-resolution postmortem imaging revealed the details of the final microstructure. Our results show that electrochemically induced solid-solid phase transformations can lead to highly concentrated stresses at the laterally propagating phase boundary which should be considered for future designs of nanostructured electrodes for Li-ion batteries.