Cell-Free Hemoglobin in the Pathophysiology of Trauma: A Scoping Review

OBJECTIVES

Cell-free hemoglobin (CFH) is a potent mediator of endothelial dysfunction, organ injury, coagulopathy, and immunomodulation in hemolysis. These mechanisms have been demonstrated in patients with sepsis, hemoglobinopathies, and those receiving transfusions. However, less is known about the role of CFH in the pathophysiology of trauma, despite the release of equivalent levels of free hemoglobin.

DATA SOURCES

Ovid MEDLINE, Embase, Web of Science Core Collection, and BIOSIS Previews were searched up to January 21, 2023, using key terms related to free hemoglobin and trauma.

DATA EXTRACTION

Two independent reviewers selected studies focused on hemolysis in trauma patients, hemoglobin breakdown products, hemoglobin-mediated injury in trauma, transfusion, sepsis, or therapeutics.

DATA SYNTHESIS

Data from the selected studies and their references were synthesized into a narrative review.

CONCLUSIONS

Free hemoglobin likely plays a role in endothelial dysfunction, organ injury, coagulopathy, and immune dysfunction in polytrauma. This is a compelling area of investigation as multiple existing therapeutics effectively block these pathways.

Postinjury platelet aggregation and venous thromboembolism

BACKGROUND

Posttraumatic venous thromboembolism (VTE) remains prevalent in severely injured patients despite chemoprophylaxis. Importantly, although platelets are central to thrombosis, they are not routinely targeted in prevention of posttraumatic VTE. Furthermore, platelets from injured patients show ex vivo evidence of increased activation yet impaired aggregation, consistent with functional exhaustion. However, the relationship of this platelet functional phenotype with development of posttraumatic VTE is unknown. We hypothesized that, following injury, impaired ex vivo platelet aggregation (PA) is associated with the development of posttraumatic VTE.

METHODS

We performed a secondary analysis of 133 severely injured patients from a prospective observational study investigating coagulation and inflammation (2011-2019). Platelet aggregation in response to stimulation with adenosine diphosphate (ADP), collagen, and thrombin was measured at presentation (preresuscitation) and 24 hours (postresuscitation). Viscoelastic clot strength and lysis were measured in parallel by thromboelastography. Multivariable regression examined relationships between PA at presentation, 24 hours, and the change (δ) in PA between presentation and 24 hours with development of VTE.

RESULTS

The 133 patients were severely injured (median Injury Severity Score, 25), and 14% developed VTE (all >48 hours after admission). At presentation, platelet count and PA were not significantly different between those with and without incident VTE. However, at 24 hours, those who subsequently developed VTE had significantly lower platelet counts (126 × 10 9 /L vs. 164 × 10 9 /L, p = 0.01) and lower PA in response to ADP ( p < 0.05), collagen ( p < 0.05), and thrombin ( p = 0.06). Importantly, the magnitude of decrease in PA (δ) from presentation to 24 hours was independently associated with development of VTE (adjusted odds ratios per 10 aggregation unit decrease: δ-ADP, 1.31 [ p = 0.03]; δ-collagen, 1.36 [ p = 0.01]; δ-thrombin, 1.41 [ p < 0.01]).

CONCLUSION

Severely injured patients with decreasing ex vivo measures of PA despite resuscitation have an increased risk of developing VTE. This may have implications for predicting development of VTE and for studying platelet targeted chemoprophylaxis regimens.

LEVEL OF EVIDENCE

Prognostic/Epidemiological; Level III.

Growing the next generation of trauma surgeon-scientists: Reflections on 20 years of research investment

INTRODUCTION

The Eastern Association for the Surgery of Trauma mission includes fostering research and providing career development opportunities. Eastern Association for the Surgery of Trauma has awarded for 20 years a research scholarship to a promising young investigator. The research mentorship efforts were expanded 5 years ago with the INVEST-C Hack-a-thon. INVEST-C provides an intensive, short-term engagement to propel junior faculty toward establishing research independence. This study investigates the impact of these programs on academic productivity.

METHODS

Pubmed records, National Institutes of Health (NIH) Reporter data, and SCOPUS h-index were acquired for all scholarship (SCH) awardees from 2002 to 2021 (n = 20) and all INVEST-C (INV) participants (2017-2020, n = 19). Current type of practice, total number of funding awards, and timing of first award were ascertained. INVEST-C participants were also surveyed on an annual basis to track their progress. Medians (interquartile range [IQR]) are reported and compared (analysis of variance).

RESULTS

Median publications (PUBs) of SCH awardees were 56 (IQR, 33-88), h-index was 16 (IQR, 12-21), and 25% of awardees have ≥1 NIH grant since their SCH. Among the last 10 awardees with a minimum of 2 years from SCH, 40% have received an NIH award compared with a mean NIH funding rate of 18.5% over the same period. For those remaining in academics (90% SCH), PUBs were higher for those >5 years (66 [IQR, 51-115]) versus <5 years from their SCH (33 [22-59]; p = 0.05), but there was no difference in h-index (16 [IQR, 14-25] vs. 15 [9-19], p = NS). Comparing the most recent 5 years of SCH to INV group, there was no difference in academic productivity as measured by total PUBs (SCH, 33 [IQR, 22-59] vs. INV, 34 [IQR, 18-44]; p = 0.7) or h-index (INV, 9 [IQR, 5-14]; p = 0.1). However, no attendee held research funding before INV, but 31.6% (6 of 19 attendees) have subsequently acquired ≥1 funding award (11 non-NIH, 1 NIH) in the short interval since participation.

CONCLUSION

Investments in research activities have translated to significant extramural funding. Those in the last 5 years have been particularly fruitful with INV participants already achieving equal median academic productivity to SCH recipients.

LEVEL OF EVIDENCE

Prognostic and Epidemiologic; Level III.

Importance of catecholamine signaling in the development of platelet exhaustion after traumatic injury

BACKGROUND

Impaired ex vivo platelet aggregation is common in trauma patients. The mechanisms driving these impairments remain incompletely understood, but functional platelet exhaustion due to excessive in vivo activation is implicated. Given platelet adrenoreceptors and known catecholamine surges after injury, impaired ex vivo platelet aggregation in trauma patients may be linked to catecholamine-induced functional platelet exhaustion.

OBJECTIVE

To determine the relationship of catecholamines with platelet-dependent hemostasis after injury and to model catecholamine-induced functional platelet exhaustion in healthy donor platelets.

PATIENTS/METHODS

Whole blood was collected from 67 trauma patients as part of a prospective cohort study. Platelet aggregometry and rotational thromboelastometry were performed, and plasma epinephrine (EPI) and norepinephrine (NE) concentrations were measured. The effect of catecholamines on healthy donor platelets was examined in a microfluidic model, with platelet aggregometry, and by flow cytometry examining surface markers of platelet activation.

RESULTS

In trauma patients, EPI and NE were associated with impaired platelet aggregation (both p < 0.05), and EPI was additionally associated with decreased viscoelastic clot strength, increased fibrinolysis, and mortality (all p < 0.05). In healthy donors, short duration incubation with EPI enhanced platelet aggregation, platelet adhesion under flow, and increased glycoprotein IIb/IIIa activation, while weaker effects were observed with NE. Compared with short incubation, longer incubation with EPI resulted in decreased platelet adhesion, platelet aggregation, and surface expression of glycoprotein IIb/IIIa.

CONCLUSIONS

These findings suggest sympathoadrenal activation in trauma patients contributes to impaired ex vivo platelet aggregation, which mechanistically may be explained by a functionally exhausted platelet phenotype under prolonged exposure to high plasma catecholamine levels.

Development and Validation of a Deep Learning Strategy for Automated View Classification of Pediatric Focused Assessment With Sonography for Trauma

OBJECTIVE

Pediatric focused assessment with sonography for trauma (FAST) is a sequence of ultrasound views rapidly performed by clinicians to diagnose hemorrhage. A technical limitation of FAST is the lack of expertise to consistently acquire all required views. We sought to develop an accurate deep learning view classifier using a large heterogeneous dataset of clinician-performed pediatric FAST.

METHODS

We developed and conducted a retrospective cohort analysis of a deep learning view classifier on real-world FAST studies performed on injured children less than 18 years old in two pediatric emergency departments by 30 different clinicians. FAST was randomly distributed to training, validation, and test datasets, 70:20:10; each child was represented in only one dataset. The primary outcome was view classifier accuracy for video clips and still frames.

RESULTS

There were 699 FAST studies, representing 4925 video clips and 1,062,612 still frames, performed by 30 different clinicians. The overall classification accuracy was 97.8% (95% confidence interval [CI]: 96.0-99.0) for video clips and 93.4% (95% CI: 93.3-93.6) for still frames. Per view still frames were classified with an accuracy: 96.0% (95% CI: 95.9-96.1) cardiac, 99.8% (95% CI: 99.8-99.8) pleural, 95.2% (95% CI: 95.0-95.3) abdominal upper quadrants, and 95.9% (95% CI: 95.8-96.0) suprapubic.

CONCLUSION

A deep learning classifier can accurately predict pediatric FAST views. Accurate view classification is important for quality assurance and feasibility of a multi-stage deep learning FAST model to enhance the evaluation of injured children.

A Delphi consensus statement for digital surgery

The use of digital technology is increasing rapidly across surgical specialities, yet there is no consensus for the term ‘digital surgery’. This is critical as digital health technologies present technical, governance, and legal challenges which are unique to the surgeon and surgical patient. We aim to define the term digital surgery and the ethical issues surrounding its clinical application, and to identify barriers and research goals for future practice. 38 international experts, across the fields of surgery, AI, industry, law, ethics and policy, participated in a four-round Delphi exercise. Issues were generated by an expert panel and public panel through a scoping questionnaire around key themes identified from the literature and voted upon in two subsequent questionnaire rounds. Consensus was defined if >70% of the panel deemed the statement important and <30% unimportant. A final online meeting was held to discuss consensus statements. The definition of digital surgery as the use of technology for the enhancement of preoperative planning, surgical performance, therapeutic support, or training, to improve outcomes and reduce harm achieved 100% consensus agreement. We highlight key ethical issues concerning data, privacy, confidentiality and public trust, consent, law, litigation and liability, and commercial partnerships within digital surgery and identify barriers and research goals for future practice. Developers and users of digital surgery must not only have an awareness of the ethical issues surrounding digital applications in healthcare, but also the ethical considerations unique to digital surgery. Future research into these issues must involve all digital surgery stakeholders including patients.

Prehospital end-tidal carbon dioxide is predictive of death and massive transfusion in injured patients: An Eastern Association for Surgery of Trauma multicenter trial

BACKGROUND

Prehospital identification of the injured patient likely to require emergent care remains a challenge. End-tidal carbon dioxide (ETCO2) has been used in the prehospital setting to monitor respiratory physiology and confirmation of endotracheal tube placement. Low levels of ETCO2 have been demonstrated to correlate with injury severity and mortality in a number of in-hospital studies. We hypothesized that prehospital ETCO2 values would be predictive of mortality and need for massive transfusion (MT) in intubated patients.

METHODS

This was a retrospective multicenter trial with 24 participating centers. Prehospital, emergency department, and hospital values were collected. Receiver operating characteristic curves were created and compared. Massive transfusion defined as >10 U of blood in 6 hours or death in 6 hours with at least 1 U of blood transfused.

RESULTS

A total of 1,324 patients were enrolled. ETCO2 (area under the receiver operating characteristic curve [AUROC], 0.67; confidence interval [CI], 0.63-0.71) was better in predicting mortality than shock index (SI) (AUROC, 0.55; CI, 0.50-0.60) and systolic blood pressure (SBP) (AUROC, 0.58; CI, 0.53-0.62) (p < 0.0005). Prehospital lowest ETCO2 (AUROC, 0.69; CI, 0.64-0.75), SBP (AUROC, 0.75; CI, 0.70-0.81), and SI (AUROC, 0.74; CI, 0.68-0.79) were all predictive of MT. Analysis of patients with normotension demonstrated lowest prehospital ETCO2 (AUROC, 0.66; CI, 0.61-0.71), which was more predictive of mortality than SBP (AUROC, 0.52; CI, 0.47-0.58) or SI (AUROC, 0.56; CI, 0.50-0.62) (p < 0.001). Lowest prehospital ETCO2 (AUROC, 0.75; CI, 0.65-0.84), SBP (AUROC, 0.63; CI, 0.54-0.74), and SI (AUROC, 0.64; CI, 0.54-0.75) were predictive of MT in normotensive patients. ETCO2 cutoff for MT was 26 mm Hg. The positive predictive value was 16.1%, and negative predictive value was high at 98.1%.

CONCLUSION

Prehospital ETCO2 is predictive of mortality and MT. ETCO2 outperformed traditional measures such as SBP and SI in the prediction of mortality. ETCO2 may outperform traditional measures in predicting need for transfusion in occult shock.

LEVEL OF EVIDENCE

Diagnostic test, level III.

A new trauma frontier: Exploratory pilot study of platelet transcriptomics in trauma patients

BACKGROUND

The earliest measurable changes to postinjury platelet biology may be in the platelet transcriptome, as platelets are known to carry messenger ribonucleic acids (RNAs), and there is evidence in other inflammatory and infectious disease states of differential and alternative platelet RNA splicing in response to changing physiology. Thus, the aim of this exploratory pilot study was to examine the platelet transcriptome and platelet RNA splicing signatures in trauma patients compared with healthy donors.

METHODS

Preresuscitation platelets purified from trauma patients (n = 9) and healthy donors (n = 5) were assayed using deep RNA sequencing. Differential gene expression analysis, weighted gene coexpression network analysis, and differential alternative splicing analyses were performed. In parallel samples, platelet function was measured with platelet aggregometry, and clot formation was measured with thromboelastography.

RESULTS

Differential gene expression analysis identified 49 platelet RNAs to have differing abundance between trauma patients and healthy donors. Weighted gene coexpression network analysis identified coexpressed platelet RNAs that correlated with platelet aggregation. Differential alternative splicing analyses revealed 1,188 splicing events across 462 platelet RNAs that were highly statistically significant (false discovery rate <0.001) in trauma patients compared with healthy donors. Unsupervised principal component analysis of these platelet RNA splicing signatures segregated trauma patients in two main clusters separate from healthy controls.

CONCLUSION

Our findings provide evidence of finetuning of the platelet transcriptome through differential alternative splicing of platelet RNA in trauma patients and that this finetuning may have relevance to downstream platelet signaling. Additional investigations of the trauma platelet transcriptome should be pursued to improve our understanding of the platelet functional responses to trauma on a molecular level.

Multi-center validation of the Bowel Injury Predictive Score (BIPS) for the early identification of need to operate in blunt bowel and mesenteric injuries

INTRODUCTION

The Bowel Injury Prediction Score (BIPS) is a tool for identifying patients at risk for blunt bowel and mesenteric injury (BBMI) requiring surgery. BIPS is calculated by assigning one point for each of the following: (1) WBC ≥ 17,000, (2) abdominal tenderness, and (3) injury grade ≥ 4 (mesenteric contusion or hematoma with bowel wall thickening or adjacent interloop fluid collection) on CT scan. A total score ≥ 2 is associated with BBMI requiring surgery. We aimed to validate the BIPS as a predictor for patients with BBMIs requiring operative intervention in a multi-center prospective study.

MATERIALS AND METHODS

Patients were prospectively enrolled at 15 U.S. trauma centers following blunt trauma with suspicion of BBMI on CT scan between July 1, 2018 and July 31, 2019. The BIPS was calculated for each patient enrolled in the study.

RESULTS

Of 313 patients, 38% had BBMI requiring operative intervention. Patients were significantly more likely to require surgery in the presence of abdominal tenderness (OR, 3.6; 95% CI, 1.6-8.0) and CT grade ≥ 4 (OR, 11.7; 95% CI, 5.7-23.7). Patients with a BIPS ≥ 2 were more than ten times more likely to require laparotomy than those with a BIPS < 2 (OR, 10.1; 95% CI, 5.0-20.4). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of a BIPS ≥ 2 for BBMI requiring surgery was 72% (CI 0.6-0.8), 78% (CI 0.7-0.8), 67% (CI 0.6-0.8), and 82% (CI 0.8-0.9), respectively. The AUROC curve for BIPS ≥ 2 was 0.75. The sensitivity, specificity, PPV, and NPV of a BIPS ≥ 2 for BBMI requiring surgery in patients with severe alteration in mental status (GCS 3-8) was 70% (CI 0.5-0.9), 92% (CI 0.8-1.0), 82% (CI 0.6-1.0), and 86% (CI 0.7-1.0), respectively.

CONCLUSION

This prospective multi-center trial validates BIPS as a predictor of BBMI requiring surgery. Calculation of BIPS during the initial evaluation of trauma patients is a useful adjunct to help general surgeons taking trauma call determine operative versus non-operative management of patients with BBMI including those with severe alteration in mental status.

Trauma and COVID-Induced Severe Rhabdomyolysis

The novel coronavirus COVID-19 has been implicated in a number of extra-pulmonary manifestations including rhabdomyolysis. It is hypothesized to be secondary to direct muscle damage from the virus. The usual treatment of rhabdomyolysis is resuscitation with aggressive fluid management to prevent acute renal failure. However, the combination of blunt thoracic trauma and COVID pneumonia has posed additional challenges for critical care management. A 68-year-old male presented to our institution after being found down for an unknown duration of time. He was diagnosed symptomatic COVID pneumonia. His traumatic injuries included 4 rib fractures, a rectus sheath hematoma, and rhabdomyolysis with a creatinine kinase (CK) level of 16,716 U/L. He was initially treated with steroids, prone positioning, and aggressive fluid administration. Despite treatment his CK level peaked at 146,328 U/L. Here we present the case of trauma and COVID-induced rhabdomyolysis with an extremely elevated CK level.

External validation of a novel signature of illness in continuous cardiorespiratory monitoring to detect early respiratory deterioration of ICU patients

Objective:

The goal of predictive analytics monitoring is the early detection of patients at high risk of subacute potentially catastrophic illnesses. An excellent example of a targeted illness is respiratory failure leading to urgent unplanned intubation, where early detection might lead to interventions that improve patient outcomes. Previously, we identified signatures of this illness in the continuous cardiorespiratory monitoring data of intensive care unit (ICU) patients and devised algorithms to identify patients at rising risk. Here, we externally validated three logistic regression models to estimate the risk of emergency intubation developed in Medical and Surgical ICUs at the University of Virginia.

Approach:

We calculated the model outputs for more than 8000 patients in the University of California—San Francisco ICUs, 240 of whom underwent emergency intubation as determined by individual chart review.

Main results:

We found that the AUC of the models exceeded 0.75 in this external population, and that the risk rose appreciably over the 12 h before the event.

Significance:

We conclude that there are generalizable physiological signatures of impending respiratory failure in the continuous cardiorespiratory monitoring data.

Outcomes after ultramassive transfusion in the modern era: An Eastern Association for the Surgery of Trauma multicenter study

BACKGROUND

Despite the widespread institution of modern massive transfusion protocols with balanced blood product ratios, survival for patients with traumatic hemorrhage receiving ultramassive transfusion (UMT) (defined as ≥20 U of packed red blood cells [RBCs]) in 24 hours) remains low and resource consumption remains high. Therefore, we aimed to identify factors associated with mortality in trauma patients receiving UMT in the modern resuscitation era.

METHODS

An Eastern Association for the Surgery of Trauma multicenter retrospective study of 461 trauma patients from 17 trauma centers who received ≥20 U of RBCs in 24 hours was performed (2014-2019). Multivariable logistic regression and Classification and Regression Tree analysis were used to identify clinical characteristics associated with mortality.

RESULTS

The 461 patients were young (median age, 35 years), male (82%), severely injured (median Injury Severity Score, 33), in shock (median shock index, 1.2; base excess, -9), and transfused a median of 29 U of RBCs, 22 U of fresh frozen plasma (FFP), and 24 U of platelets (PLT). Mortality was 46% at 24 hours and 65% at discharge. Transfusion of RBC/FFP ≥1.5:1 or RBC/PLT ≥1.5:1 was significantly associated with mortality, most pronounced for the 18% of patients who received both RBC/PLT and RBC/FFP ≥1.5:1 (odds ratios, 3.11 and 2.81 for mortality at 24 hours and discharge; both p < 0.01). Classification and Regression Tree identified that age older than 50 years, low initial Glasgow Coma Scale, thrombocytopenia, and resuscitative thoracotomy were associated with low likelihood of survival (14-26%), while absence of these factors was associated with the highest survival (71%).

CONCLUSION

Despite modern massive transfusion protocols, one half of trauma patients receiving UMT are transfused with either RBC/FFP or RBC/PLT in unbalanced ratios ≥1.5:1, with increased associated mortality. Maintaining focus on balanced ratios during UMT is critical, and consideration of advanced age, poor initial mental status, thrombocytopenia, and resuscitative thoracotomy can aid in prognostication.

LEVEL OF EVIDENCE

Prognostic, level III.

Early abnormal fibrinolysis and mortality in patients with thermal injury: a prospective cohort study

INTRODUCTION

Abnormal fibrinolysis early after injury has been associated with increased mortality in trauma patients, but no studies have addressed patients with burn injury. This prospective cohort study aimed to characterize fibrinolytic phenotypes in burn patients and to see if they were associated with mortality.

METHODS

Patients presenting to a regional burn centre within 4 h of thermal injury were included. Blood was collected for sequential viscoelastic measurements using thromboelastography (RapidTEG™) over 12 h. The percentage decrease in clot strength 30 min after the time of maximal clot strength (LY30) was used to categorize patients into hypofibrinolytic/fibrinolytic shutdown (SD), physiological (PHYS) and hyperfibrinolytic (HF) phenotypes. Injury characteristics, demographics and outcomes were compared.

RESULTS

Of 115 included patients, just over two thirds were male. Overall median age was 40 (i.q.r. 28-57) years and median total body surface area (TBSA) burn was 13 (i.q.r. 6-30) per cent. Some 42 (36.5 per cent) patients had severe burns affecting over 20 per cent TBSA. Overall mortality was 18.3 per cent. At admission 60.0 per cent were PHYS, 30.4 per cent were SD and 9.6 per cent HF. HF was associated with increased risk of mortality on admission (odds ratio 12.61 (95 per cent c.i. 1.12 to 142.57); P = 0.041) but not later during the admission when its incidence also decreased. Admission SD was not associated with mortality, but incidence increased and by 4 h and beyond, SD was associated with increased mortality, compared with PHYS (odds ratio 8.27 (95 per cent c.i. 1.16 to 58.95); P = 0.034).

DISCUSSION

Early abnormal fibrinolytic function is associated with mortality in burn patients.

Emergency Department Length of Stay and Mortality in Critically Injured Patients

OBJECTIVE

Multicenter data from 2 decades ago demonstrated that critically ill and injured patients spending more than 6 hours in the emergency department (ED) before transfer to the intensive care unit (ICU) had higher mortality rates. A contemporary analysis of ED length of stay in critically injured patients at American College of Surgeons' Trauma Quality Improvement Program (ACS-TQIP) centers was performed to test whether prolonged ED length of stay is still associated with mortality.

METHODS

This was an observational cohort study of critically injured patients admitted directly to ICU from the ED in ACS-TQIP centers from 2010-2015. Spending more than 6 hours in the ED was defined as prolonged ED length of stay. Patients with prolonged ED length of stay were matched to those with non-prolonged ED length of stay and mortality was compared.

MAIN RESULTS

A total of 113,097 patients were directly admitted from the ED to the ICU following injury. The median ED length of stay was 167 minutes. Prolonged ED length of stay occurred in 15,279 (13.5%) of patients. Women accounted for 29.4% of patients with prolonged ED length of stay but only 25.8% of patients with non-prolonged ED length of stay, P < 0.0001. Mortality rates were similar after matching-4.5% among patients with prolonged ED length of stay versus 4.2% among matched controls. Multivariable logistic regression of the matched cohorts demonstrated prolonged ED length of stay was not associated with mortality. However, women had higher adjusted mortality compared to men Odds Ratio = 1.41, 95% Confidence Interval 1.28 -1.61, P < 0.0001.

CONCLUSION

Prolonged ED length of stay is no longer associated with mortality among critically injured patients. Women are more likely to have prolonged ED length of stay and mortality.

Good Platelets Gone Bad: The Effects of Trauma Patient Plasma on Healthy Platelet Aggregation

BACKGROUND

Altered postinjury platelet behavior is recognized in the pathophysiology of trauma-induced coagulopathy (TIC), but the mechanisms remain largely undefined. Studies suggest that soluble factors released by injury may inhibit signaling pathways and induce structural changes in circulating platelets. Given this, we sought to examine the impact of treating healthy platelets with plasma from injured patients. We hypothesized that healthy platelets treated ex-vivo with plasma from injured patients with shock would impair platelet aggregation, while treatment with plasma from injured patients with significant injury burden, but without shock, would enhance platelet aggregation.

METHODS

Plasma samples were isolated from injured patients (pretransfusion) and healthy donors at a Level I trauma center and stored at -80°C. Plasma samples from four separate patients in each of the following stratified clinical groups were used: mild injury/no shock (injury severity score [ISS] 2-15, base excess [BE]>-6), mild injury/with shock (ISS 2-15, BE≤-6), severe injury/no shock (ISS>25, BE>-6), severe injury/with shock (ISS>25, BE≤-6), minimal injury (ISS 0/1, BE>-6), and healthy. Platelets were isolated from three healthy adult males and were treated with plasma for 30 min. Aggregation was stimulated with a thrombin receptor agonist and measured via multiple-electrode platelet aggregometry. Data were normalized to HEPES Tyrode's (HT) buffer-only treated platelets. Associations of plasma treatment groups with platelet aggregation measures were tested with Mann-Whitney U tests.

RESULTS

Platelets treated with plasma from patients with shock (regardless of degree of injury) had significantly impaired thrombin-stimulated aggregation compared with platelets treated with plasma from patients without shock (P = 0.002). Conversely, platelets treated with plasma from patients with severe injury, but without shock, had amplified thrombin-stimulated aggregation (P = 0.030).

CONCLUSION

Shock-mediated soluble factors impair platelet aggregation, and tissue injury-mediated soluble factors amplify platelet aggregation. Future characterization of these soluble factors will support development of novel treatments of TIC.

Insights into the association between coagulopathy and inflammation: abnormal clot mechanics are a warning of immunologic dysregulation following major injury

Background

Severe injury initiates a complex physiologic response encompassing multiple systems and varies phenotypically between patients. Trauma-induced coagulopathy may be an early warning of a poorly coordinated response at the molecular level, including a deleterious immunologic response and worsening of shock states. The onset of trauma-induced coagulopathy (TIC) may be subtle however. In previous work, we identified an early warning sign of coagulopathy from the admission thromboelastogram, called the MAR ratio. We hypothesized that a low MAR ratio would be associated with specific derangements in the inflammatory response.

Methods

In this prospective, observational study, 88 blunt trauma patients admitted to the intensive care unit (ICU) were identified. Concentrations of inflammatory mediators were recorded serially over the course of a week and the MAR ratio was calculated from the admission thromboelastogram. Correlation analysis was used to assess the relationship between MAR and inflammatory mediators. Dynamic network analysis was used to assess coordination of immunologic response.

Results

Seventy-nine percent of patients were male and mean age was 37 years (SD 12). The mean ISS was 30.2 (SD 12) and mortality was 7.2%. CRITICAL patients (MAR ratio ≤14.2) had statistically higher shock volumes at three time points in the first day compared to NORMAL patients (MAR ratio >14.2). CRITICAL patients had significant differences in IL-6 (P=0.0065), IL-8 (P=0.0115), IL-10 (P=0.0316) and MCP-1 (P=0.0039) concentrations compared to NORMAL. Differences in degree of expression and discoordination of immune response continued in CRITICAL patients throughout the first day.

Conclusions

The admission MAR ratio may be the earliest warning signal of a pathologic inflammatory response associated with hypoperfusion and TIC. A low MAR ratio is an early indication of complicated dysfunction of multiple molecular processes following trauma.

Cost-effectiveness evaluation of the PROPPR trial transfusion protocols

BACKGROUND

There have been no prior investigations of the cost effectiveness of transfusion strategies for trauma resuscitation. The Pragmatic, Randomized, Optimal Platelet and Plasma Ratios (PROPPR) study was a Phase III multisite, randomized trial in 680 subjects comparing the efficacy of 1:1:1 transfusion ratios of plasma and platelets to red blood cells with the 1:1:2 ratio. We hypothesized that 1:1:1 transfusion results in an acceptable incremental cost-effectiveness ratio, when estimated using patients' age-specific life expectancy and cost of care during the 30-day PROPPR trial period.

STUDY DESIGN AND METHODS

International Classification of Diseases, Ninth Revision codes were prospectively collected, and subjects were matched 1:2 to subjects in the Healthcare Utilization Program State Inpatient Data to estimate cost weights. We used a decision tree analysis, combined with standard costs and estimated years of expected survival to determine the cost effectiveness of the two treatments.

RESULTS

The 1:1:1 group had higher overall costs for the blood products but were more likely to achieve hemostasis and decreased hemorrhagic death by 24 hours (p = 0.006). For every 100 patients treated in the 1:1:1 group, eight more achieved hemostasis than in the 1:1:2 group. At 30 days, the total hospital cost per 100 patients was $5.6 million in the 1:1:1 group compared with $5.0 million in the 1:1:2 group. For each 100 patients, the 1:1:1 group had 218.5 more years of life expectancy. This was at a cost of $2994 per year gained.

CONCLUSION

The 1:1:1 transfusion ratio in severely injured hemorrhaging trauma patients is a very cost-effective strategy for increasing hemostasis and decreasing trauma deaths.

Gender distribution and leadership trends in trauma surgery societies

Introduction

Women are under-represented in the surgical disciplines and gender bias is believed to play a factor. We aimed to understand the gender distribution of membership, leadership opportunities, and scientific contributions to annual trauma professional meetings as a case study of gender issues in trauma surgery.

Methods

Retrospective collection of membership, leadership, presentation and publication data from 2016 to 2018 Trauma/Acute Care Surgery/Surgical Critical Care (TACSCC) Annual Meetings. Gender was assigned based on self-identification in demographic information, established relationships, or public sources.

Results

Women remain under-represented with only 28.1% of those ascertaining American Board of Surgery certification in critical care self-identifying as female. The proportion of female members in Eastern Association for the Surgery of Trauma (EAST) was comparable (29.4%), slightly lower for Western Trauma Association (WTA) (19.0%), and lowest for American Association for the Surgery of Trauma (AAST) (12.8%, p<0.05). In contrast, AAST had the highest proportion of female participants in executive leadership (AAST 32.5%, WTA 19.0%, EAST 18.8%) and WTA the highest for committee chairs (WTA 33.3%, AAST 27.8%, EAST 20.5%). AAST had the most significant increase in executive leadership during the last 3 years (AAST 28.6% to 41.6%). Invited lectureships, masters, panelists and senior author scientific contributions demonstrated the largest gap of academic representation of female TACSCC surgeons.

Conclusion

Fewer women than men pursue careers in the trauma field. Continuing to provide mentorship, leadership, and scientific recognition will increase gender diversity in TACSCC. We must continue to promote, sponsor, recognize, invite, and elect ‘her’.

Level of evidence

III, Epidemiology.

Artificial neural networks can predict trauma volume and acuity regardless of center size and geography: A multicenter study

BACKGROUND

Trauma has long been considered unpredictable. Artificial neural networks (ANN) have recently shown the ability to predict admission volume, acuity, and operative needs at a single trauma center with very high reliability. This model has not been tested in a multicenter model with differing climate and geography. We hypothesize that an ANN can accurately predict trauma admission volume, penetrating trauma admissions, and mean Injury Severity Score (ISS) with a high degree of reliability across multiple trauma centers.

METHODS

Three years of admission data were collected from five geographically distinct US Level I trauma centers. Patients with incomplete data, pediatric patients, and primary thermal injuries were excluded. Daily number of traumas, number of penetrating cases, and mean ISS were tabulated from each center along with National Oceanic and Atmospheric Administration data from local airports. We trained a single two-layer feed-forward ANN on a random majority (70%) partitioning of data from all centers using Bayesian Regularization and minimizing mean squared error. Pearson's product-moment correlation coefficient was calculated for each partition, each trauma center, and for high- and low-volume days (>1 standard deviation above or below mean total number of traumas).

RESULTS

There were 5,410 days included. There were 43,380 traumas, including 4,982 penetrating traumas. The mean ISS was 11.78 (SD = 6.12). On the training partition, we achieved R = 0.8733. On the testing partition (new data to the model), we achieved R = 0.8732, with a combined R = 0.8732. For high- and low-volume days, we achieved R = 0.8934 and R = 0.7963, respectively.

CONCLUSION

An ANN successfully predicted trauma volumes and acuity across multiple trauma centers with very high levels of reliability. The correlation was highest during periods of peak volume. This can potentially provide a framework for determining resource allocation at both the trauma system level and the individual hospital level.

LEVEL OF EVIDENCE

Care Management, level IV.

Predictors of postinjury acute respiratory distress syndrome: Lung injury persists in the era of hemostatic resuscitation

BACKGROUND

Acute respiratory distress syndrome (ARDS) following trauma is historically associated with crystalloid and blood product exposure. Advances in resuscitation have occurred over the last decade, but their impact on ARDS is unknown. We sought to investigate predictors of postinjury ARDS in the era of hemostatic resuscitation.

METHODS

Data were prospectively collected from arrival to 28 days for 914 highest-level trauma activations who required intubation and survived more than 6 hours from 2005 to 2016 at a Level I trauma center. Patients with ratio of partial pressure of oxygen to fraction of inspired oxygen of 300 mmHg or less during the first 8 days were identified. Two blinded expert clinicians adjudicated all chest radiographs for bilateral infiltrates in the first 8 days. Those with left-sided heart failure detected were excluded. Multivariate logistic regression was used to define predictors of ARDS.

RESULTS

Of the 914 intubated patients, 63% had a ratio of partial pressure of oxygen to fraction of inspired oxygen of 300 or less, and 22% developed ARDS; among the ARDS cases, 57% were diagnosed early (in the first 24 hours), and 43% later. Patients with ARDS diagnosed later were more severely injured (ISS 32 vs. 20, p = 0.001), with higher rates of blunt injury (84% vs. 72%, p = 0.008), chest injury (58% vs. 36%, p < 0.001), and traumatic brain injury (72% vs. 48%, p < 0.001) compared with the no ARDS group. In multivariate analysis, head/chest Abbreviated Injury Score scores, crystalloid from 0 to 6 hours, and platelet transfusion from 0 to 6 hours and 7 to 24 hours were independent predictors of ARDS developing after 24 hours.

CONCLUSIONS

Blood and plasma transfusion were not independently associated with ARDS. However, platelet transfusion was a significant independent risk factor. The role of platelets warrants further investigation but may be mechanistically explained by lung injury models of pulmonary platelet sequestration with peripheral thrombocytopenia.

LEVEL OF EVIDENCE

Prognostic study, level IV.

Dynamic multi-outcome prediction after injury: Applying adaptive machine learning for precision medicine in trauma

OBJECTIVE

Machine learning techniques have demonstrated superior discrimination compared to conventional statistical approaches in predicting trauma death. The objective of this study is to evaluate whether machine learning algorithms can be used to assess risk and dynamically identify patient-specific modifiable factors critical to patient trajectory for multiple key outcomes after severe injury.

METHODS

SuperLearner, an ensemble machine-learning algorithm, was applied to prospective observational cohort data from 1494 critically-injured patients. Over 1000 agnostic predictors were used to generate prediction models from multiple candidate learners for outcomes of interest at serial time points post-injury. Model accuracy was estimated using cross-validation and area under the curve was compared to select among predictors. Clinical variables responsible for driving outcomes were estimated at each time point.

RESULTS

SuperLearner fits demonstrated excellent cross-validated prediction of death (overall AUC 0.94-0.97), multi-organ failure (overall AUC 0.84-0.90), and transfusion (overall AUC 0.87-0.9) across multiple post-injury time points, and good prediction of Acute Respiratory Distress Syndrome (overall AUC 0.84-0.89) and venous thromboembolism (overall AUC 0.73-0.83). Outcomes with inferior data quality included coagulopathic trajectory (AUC 0.48-0.88). Key clinical predictors evolved over the post-injury timecourse and included both anticipated and unexpected variables. Non-random missingness of data was identified as a predictor of multiple outcomes over time.

CONCLUSIONS

Machine learning algorithms can be used to generate dynamic prediction after injury while avoiding the risk of over- and under-fitting inherent in ad hoc statistical approaches. SuperLearner prediction after injury demonstrates promise as an adaptable means of helping clinicians integrate voluminous, evolving data on severely-injured patients into real-time, dynamic decision-making support.

Discrepancies between conventional and viscoelastic assays in identifying trauma-induced coagulopathy

BACKGROUND

Trauma-induced coagulopathy can present as abnormalities in a conventional or viscoelastic coagulation assay or both. We hypothesized that patients with discordant coagulopathies reflect different clinical phenotypes.

METHODS

Blood samples were collected prospectively from critically injured patients upon arrival at two urban Level I trauma centers. International normalized ratio (INR), partial thromboplastin time (PTT), thromboelastography (TEG), and coagulation factors were assayed.

RESULTS

278 patients (median ISS 17, mortality 26%) were coagulopathic: 20% with isolated abnormal INR and/or PTT (CONVENTIONAL), 49% with isolated abnormal TEG (VISCOELASTIC), and 31% with abnormal INR/PTT and TEG (BOTH). Compared with VISCOELASTIC, CONVENTIONAL and BOTH had higher ISS, lower GCS, larger base deficit, and decreased factor activities (all p < 0.017). They received more blood products and had more ICU/ventilation days (all p < 0.017). Mortality was higher in CONVENTIONAL (40%) and BOTH (49%) than VISCOELASTIC (6%, p < 0.017).

CONCLUSIONS

Although TEG-guided resuscitation improves survival after injury, INR and PTT identify coagulopathic patients with highest mortality regardless of TEG and likely represent distinct mechanisms independent of biochemical clot strength.

Identifying temporal patterns in trauma admissions: Informing resource allocation

BACKGROUND

Increased knowledge of the temporal patterns in the distribution of trauma admissions could be beneficial to staffing and resource allocation efforts. However, little work has been done to understand how this distribution varies based on patient acuity, trauma mechanism or need for intervention. We hypothesize that temporal patterns exist in the distribution of trauma admissions, and that deep patterns exist when traumas are analyzed by their type and severity.

STUDY DESIGN

We conducted a cross-sectional observational study of adult patient flow at a level one trauma center over three years, 7/1/2013-6/30/2016. Primary thermal injuries were excluded. Frequency analysis was performed for patients grouped by ED disposition and mechanism against timing of admission; in subgroup analysis additional exclusion criteria were imposed.

RESULTS

10,684 trauma contacts were analyzed. Trauma contacts were more frequent on Saturdays and Sundays than on weekdays (p<0.001). Peak arrival time was centered around evening shift change (6-7pm), but differed based on ED disposition: OR and ICU or Step-Down admissions (p = 0.0007), OR and floor admissions (p<0.0001), and ICU or Step-Down and floor admissions (p<0.0001). Step-Down and ICU arrival times (p = 0.42) were not different. Penetrating injuries peaked later than blunt (p<0.0001). Trauma varies throughout the year; we establish a high incidence trauma season (April to late October). Different mechanisms have varying dependence upon season; Motorcycle crashes (MCCs) have the greatest dependence.

CONCLUSION

We identify new patterns in the temporal and seasonal variation of trauma and of specific mechanisms of injury, including the novel findings that 1) penetrating trauma tends to present at later times than blunt, and 2) critically ill patients requiring an OR tend to present later than those who are less acute and require an ICU or Step-Down unit. These patients present later than those who are admitted to the floor. Penetrating trauma patients arriving later than blunt may be the underlying reason why operative patients arrive later than other patients.

Banning open carry of unloaded handguns decreases firearm-related fatalities and hospital utilization

Background

Since 1967, in California it has been illegal to openly carry a loaded firearm in public except when engaged in hunting or law enforcement. However, beginning January 1, 2012, public open carry of unloaded handguns also became illegal. Fatal and non-fatal (NF) firearm injuries were examined before and after adoption of the 2012 ban to quantify the effect of the new law on public health.

Methods

State-level data were obtained directly from California and nine other US state inpatient and emergency department (ED) discharge databases, and the Centers for Disease Control Web-Based Injury Statistics Query and Reporting System. Case numbers of firearm fatalities, NF hospitalizations, NF ED visits, and state-level population estimates were extracted. Each incident was classified as unintentional, self-inflicted, or assault. Crude incidence rates were calculated. The strength of gun laws was quantified using the Brady grade. There were no changes to open carry in these nine states during the study. Using a difference-in-difference technique, the rate trends 3 years preban and postban were compared.

Results

The 2012 open carry ban resulted in a significantly lower incident rate of both firearm-related fatalities and NF hospitalizations (p<0.001). The effect of the law remained significant when controlling for baseline state gun laws (p<0.001). Firearm incident rate drops in California were significant for male homicide (p=0.023), hospitalization for NF assault (p=0.021 male; p=0.025 female), and ED NF assault visits (p=0.04). No significant decreases were observed by sex for suicides or unintentional injury. Changing the law saved an estimated 337 lives (3.6% fewer deaths) and 1285 NF visits in California during the postban period.

Discussion

Open carry ban decreases fatalities and healthcare utilization even in a state with baseline strict gun laws. The most significant impact is from decreasing firearm-related fatal and NF assaults.

Level of evidence

III, epidemiology.

Risk Factors for the Development of Acute Respiratory Distress Syndrome Following Hemorrhage

BACKGROUND

The Pragmatic Randomized Optimal Platelet and Plasma Ratios (PROPPR) study evaluated the effects of plasma and platelets on hemostasis and mortality after hemorrhage. The pulmonary consequences of resuscitation strategies that mimic whole blood, remain unknown.

METHODS

A secondary analysis of the PROPPR study was performed. Injured patients predicted to receive a massive transfusion were randomized to 1:1:1 versus 1:1:2 plasma-platelet-red blood cell ratios at 12 Level I North American trauma centers. Patients with survival >24 h, an intensive care unit (ICU) stay, and a recorded PaO2/FiO2 (P/F) ratio were included. Acute respiratory distress syndrome (ARDS) was defined as a P/F ratio < 200, with bilateral pulmonary infiltrates, and adjudicated by investigators.

RESULTS

Four hundred fifty-four patients were reviewed (230 received 1:1:1, 224 1:1:2). Age, sex, injury mechanism, and regional abbreviated injury scale (AIS) scores did not differ between cohorts. Tidal volume, positive end-expiratory pressure, and lowest P/F ratio did not differ. No significant differences in ARDS rates (14.8% vs. 18.4%), ventilator-free (24 vs. 24) or ICU-free days (17.5 vs. 18), hospital length of stay (22 days vs. 18 days), or 30-day mortality were found (28% vs. 28%). ARDS was associated with blunt injury (OR 3.61 [1.53-8.81] P < 0.01) and increasing chest AIS (OR 1.40 [1.15-1.71] P < 0.01). Each 500 mL of crystalloid infused during hours 0 to 6 was associated with a 9% increase in the rate of ARDS (OR 1.09 [1.04-1.14] P < 0.01). Blood given at 0 to 6 or 7 to 24 h were not risk factors for lung injury.

CONCLUSION

Acute crystalloid exposure, but not blood products, is a potentially modifiable risk factor for the prevention of ARDS following hemorrhage.

Health care utilization and the cost of posttraumatic acute respiratory distress syndrome care

BACKGROUND

Posttraumatic acute respiratory distress syndrome (ARDS) is associated with prolonged mechanical ventilation and longer hospitalizations. The relationship between posttraumatic ARDS severity and financial burden has not been previously studied. We hypothesized that increasing ARDS severity is associated with incrementally higher health care costs.

METHODS

Adults arriving as the highest level of trauma activation were enrolled in an ongoing prospective cohort study. Patients who survived 6 hours or longer are included in the analysis. Blinded review of chest radiographs was performed by two independent physicians for any intubated patient with PaO2:FIO2 ratio of 300 mmHg or lower during the first 8 days of admission. The severity of ARDS was classified by the Berlin criteria. Hospital charge data were used to perform standard costing analysis.

RESULTS

Acute respiratory distress syndrome occurred in 13% (203 of 1,586). The distribution of disease severity was 33% mild, 42% moderate, and 25% severe. Patients with ARDS were older (41 years vs. 35 years, p < 0.01), had higher median Injury Severity Score (30 vs. 10, p < 0.01), more chest injury (Abbreviated Injury Scale score, ≥ 3: 51% vs. 21%, p < 0.01), and blunt mechanisms (85% vs. 53%, p < 0.01). By ARDS severity, there was no significant difference in age, mechanism, or rate of traumatic brain injury. Increasing ARDS severity was associated with higher Injury Severity Score and higher mortality rates. Standardized total hospital charges were fourfold higher for patients who developed ARDS compared with those who did not develop ARDS (US $434,000 vs. US $96,000; p < 0.01). Furthermore, the daily hospital charges significantly increased across categories of worsening ARDS severity (mild, US $20,451; moderate, US $23,994; severe, US $33,316; p < 0.01).

CONCLUSION

The development of posttraumatic ARDS is associated with higher health care costs. Among trauma patients who develop ARDS, total hospital charges per day increase with worsening severity of disease. Prevention, early recognition, and treatment of ARDS after trauma are potentially important objectives for efforts to control health care costs in this population.

LEVEL OF EVIDENCE

Economic and value-based evaluations, level IV.

Circulation first - the time has come to question the sequencing of care in the ABCs of trauma; an American Association for the Surgery of Trauma multicenter trial

Background

The traditional sequence of trauma care: Airway, Breathing, Circulation (ABC) has been practiced for many years. It became the standard of care despite the lack of scientific evidence. We hypothesized that patients in hypovolemic shock would have comparable outcomes with initiation of bleeding treatment (transfusion) prior to intubation (CAB), compared to those patients treated with the traditional ABC sequence.

Methods

This study was sponsored by the American Association for the Surgery of Trauma multicenter trials committee. We performed a retrospective analysis of all patients that presented to trauma centers with presumptive hypovolemic shock indicated by pre-hospital or emergency department hypotension and need for intubation from January 1, 2014 to July 1, 2016. Data collected included demographics, timing of intubation, vital signs before and after intubation, timing of the blood transfusion initiation related to intubation, and outcomes.

Results

From 440 patients that met inclusion criteria, 245 (55.7%) received intravenous blood product resuscitation first (CAB), and 195 (44.3%) were intubated before any resuscitation was started (ABC). There was no difference in ISS, mechanism, or comorbidities. Those intubated prior to receiving transfusion had a lower GCS than those with transfusion initiation prior to intubation (ABC: 4, CAB:9, p = 0.005). Although mortality was high in both groups, there was no statistically significant difference (CAB 47% and ABC 50%). In multivariate analysis, initial SBP and initial GCS were the only independent predictors of death.

Conclusion

The current study highlights that many trauma centers are already initiating circulation first prior to intubation when treating hypovolemic shock (CAB), even in patients with a low GCS. This practice was not associated with an increased mortality. Further prospective investigation is warranted.

Trial registration

IRB approval number: HM20006627. Retrospective trial not registered.

Trauma Early Mortality Prediction Tool (TEMPT) for assessing 28-day mortality

Background

Prior mortality prediction models have incorporated severity of anatomic injury quantified by Abbreviated Injury Severity Score (AIS). Using a prospective cohort, a new score independent of AIS was developed using clinical and laboratory markers present on emergency department presentation to predict 28-day mortality.

Methods

All patients (n=1427) enrolled in an ongoing prospective cohort study were included. Demographic, laboratory, and clinical data were recorded on admission. True random number generator technique divided the cohort into derivation (n=707) and validation groups (n=720). Using Youden indices, threshold values were selected for each potential predictor in the derivation cohort. Logistic regression was used to identify independent predictors. Significant variables were equally weighted to create a new mortality prediction score, the Trauma Early Mortality Prediction Tool (TEMPT) score. Area under the curve (AUC) was tested in the validation group. Pairwise comparison of Trauma Injury Severity Score (TRISS), Revised Trauma Score, Glasgow Coma Scale, and Injury Severity Score were tested against the TEMPT score.

Results

There was no difference between baseline characteristics between derivation and validation groups. In multiple logistic regression, a model with presence of traumatic brain injury, increased age, elevated systolic blood pressure, decreased base excess, prolonged partial thromboplastin time, increased international normalized ratio (INR), and decreased temperature accurately predicted mortality at 28 days (AUC 0.93, 95% CI 0.90 to 0.96, P<0.001). In the validation cohort, this score, termed TEMPT, predicted 28-day mortality with an AUC 0.94 (95% CI 0.92 to 0.97). The TEMPT score preformed similarly to the revised TRISS score for severely injured patients and was highly predictive in those having mild to moderate injury.

Discussion

TEMPT is a simple AIS-independent mortality prediction tool applicable very early following injury. TEMPT provides an AIS-independent score that could be used for early identification of those at risk of doing poorly following even minor injury.

Level of evidence

Level II.

Characterizing the gut microbiome in trauma: significant changes in microbial diversity occur early after severe injury

Background

Recent studies have demonstrated the vital influence of commensal microbial communities on human health. The central role of the gut in the response to injury is well described; however, no prior studies have used culture-independent profiling techniques to characterize the gut microbiome after severe trauma. We hypothesized that in critically injured patients, the gut microbiome would undergo significant compositional changes in the first 72 hours after injury.

Methods

Trauma stool samples were prospectively collected via digital rectal examination at the time of presentation (0 hour). Patients admitted to the intensive care unit (n=12) had additional stool samples collected at 24 hours and/or 72 hours. Uninjured patients served as controls (n=10). DNA was extracted from stool samples and 16S rRNA-targeted PCR amplification was performed; amplicons were sequenced and binned into operational taxonomic units (OTUs; 97% sequence similarity). Diversity was analyzed using principle coordinates analyses, and negative binomial regression was used to determine significantly enriched OTUs.

Results

Critically injured patients had a median Injury Severity Score of 27 and suffered polytrauma. At baseline (0 hour), there were no detectable differences in gut microbial community diversity between injured and uninjured patients. Injured patients developed changes in gut microbiome composition within 72 hours, characterized by significant alterations in phylogenetic composition and taxon relative abundance. Members of the bacterial orders Bacteroidales, Fusobacteriales and Verrucomicrobiales were depleted during 72 hours, whereas Clostridiales and Enterococcus members enriched significantly.

Discussion

In this initial study of the gut microbiome after trauma, we demonstrate that significant changes in phylogenetic composition and relative abundance occur in the first 72 hours after injury. This rapid change in intestinal microbiota represents a critical phenomenon that may influence outcomes after severe trauma. A better understanding of the nature of these postinjury changes may lead to the ability to intervene in otherwise pathological clinical trajectories.

Level of evidence

III

Study type

Prognostic/epidemiological

Finding the signal in the noise: Could social media be utilized for early hospital notification of multiple casualty events?

Introduction

Delayed notification and lack of early information hinder timely hospital based activations in large scale multiple casualty events. We hypothesized that Twitter real-time data would produce a unique and reproducible signal within minutes of multiple casualty events and we investigated the timing of the signal compared with other hospital disaster notification mechanisms.

Methods

Using disaster specific search terms, all relevant tweets from the event to 7 days post-event were analyzed for 5 recent US based multiple casualty events (Boston Bombing [BB], SF Plane Crash [SF], Napa Earthquake [NE], Sandy Hook [SH], and Marysville Shooting [MV]). Quantitative and qualitative analysis of tweet utilization were compared across events.

Results

Over 3.8 million tweets were analyzed (SH 1.8 m, BB 1.1m, SF 430k, MV 250k, NE 205k). Peak tweets per min ranged from 209–3326. The mean followers per tweeter ranged from 3382–9992 across events. Retweets were tweeted a mean of 82–564 times per event. Tweets occurred very rapidly for all events (<2 mins) and represented 1% of the total event specific tweets in a median of 13 minutes of the first 911 calls. A 200 tweets/min threshold was reached fastest with NE (2 min), BB (7 min), and SF (18 mins). If this threshold was utilized as a signaling mechanism to place local hospitals on standby for possible large scale events, in all case studies, this signal would have preceded patient arrival. Importantly, this threshold for signaling would also have preceded traditional disaster notification mechanisms in SF, NE, and simultaneous with BB and MV.

Conclusions

Social media data has demonstrated that this mechanism is a powerful, predictable, and potentially important resource for optimizing disaster response. Further investigated is warranted to assess the utility of prospective signally thresholds for hospital based activation.

Reconsidering the Resources Needed for Multiple Casualty Events: Lessons Learned From the Crash of Asiana Airlines Flight 214

IMPORTANCE

To date, a substantial portion of multiple casualty incident literature has focused exclusively on prehospital and emergency department resources needed for optimal disaster response. Thus, inpatient resources required to care for individuals injured in multiple casualty events are not well described.

OBJECTIVE

To highlight the resources beyond initial emergency department triage needed for multiple casualty events, using one of the largest commercial aviation disasters in modern US history as a case study.

DESIGN, SETTING, AND PARTICIPANTS

Prospective case series of injured individuals treated at an urban level I trauma center following the crash of Asiana Airlines flight 214 on July 6, 2013. This analysis was conducted between June 1, 2014, and December 1, 2015.

EXPOSURE

Commercial jetliner crash.

MAIN OUTCOMES AND MEASURES

Medical records, imaging data, nursing overtime, blood bank records, and trauma registry data were analyzed. Disaster logs, patient injuries, and blood product data were prospectively collected during the incident.

RESULTS

Among 307 people aboard the flight, 192 were injured; 63 of the injured patients were initially evaluated at San Francisco General Hospital and Trauma Center (the highest number at any of the receiving medical facilities; age range, 4-74 years [23 were aged <17 years and 3 were aged >60 years]; median injury severity score of 19 admitted patients, 9 [range, 9-45]), including the highest number of critically injured patients (10 of 12). Despite the high impact of the crash, only 3 persons (<1%) died, including 1 in-hospital death. Among the 63 patients, 32 (50.8%) underwent a computed tomographic imaging study, with imaging of the abdomen and pelvis being the most common. Sixteen of the 32 patients undergoing computed tomography (50.0%) had a positive finding on at least 1 scan. Nineteen patients had major injuries and required admission, with 5 taken directly from the emergency department to the operating room. The most frequent injury was spinal fracture (13 patients). In the first 48 hours, 15 operations were performed and 117 total units of blood products were transfused. A total of 370 nursing overtime hours were required to treat the injured patients on the day of the event.

CONCLUSIONS AND RELEVANCE

Proper disaster preparedness requires attention to hospital-level needs beyond initial emergency department triage. The Asiana Airlines flight 214 crash highlights the need to plan for high use of advanced imaging, blood products, operating room availability, nursing resources, and management of inpatient hospital beds.

Discovering the truth about life after discharge: Long-term trauma-related mortality

BACKGROUND

Outcome after traumatic injury has typically been limited to the determination at time of discharge or brief follow-up. This study investigates the natural history of long-term survival after trauma.

METHODS

All highest-level activation patients prospectively enrolled in an ongoing cohort study from 2005 to 2012 were selected. To allow for long-term follow-up, patients had to be enrolled at least 1 year before the latest available data from the National Death Index (NDI, 2013). Time and cause of mortality was determined based on death certificates. Survival status was determined by the latest date of either care in our institution or NDI query. Kaplan-Meier curves were created stratified for Injury Severity Score (ISS). Survival was compared with estimated actuarial survival based on age, sex, and race.

RESULTS

A total of 908 highest-level activation patients (median ISS, 18) were followed up for a median 1.7 years (interquartile range 1.0-2.9; maximum, 9.8 years). Survival data were available on 99.8%. Overall survival was 73% (663 of 908). For those with at least 2-year follow-up, survival was only 62% (317 of 509). Severity of injury predicted long-term survival (p < 0.0001) with those having ISS of 25 or greater with the poorest outcome (57% survival at 5 years). For all ISS groups, survival was worse than predicted actuarial survival (p < 0.001). When excluding early deaths (≤30 days), observed survival was still significantly lower than estimated actuarial survival (p < 0.002). Eighteen percent (44 of 245 deaths) of all deaths occurred after 30 days. Among late deaths, 53% occurred between 31 days and 1 year after trauma. Trauma-related mortality was the leading cause of postdischarge death, accounting for 43% of the late deaths.

CONCLUSION

Postdischarge deaths represent a significant percentage of total trauma-related mortality. Despite having "survived" to leave the hospital, long-term survival was worse than predicted actuarial survival, suggesting that the mortality from injury does not end at "successful" hospital discharge.

LEVEL OF EVIDENCE

Prognostic study, level III.

Statistical Machines for Trauma Hospital Outcomes Research: Application to the PRospective, Observational, Multi-Center Major Trauma Transfusion (PROMMTT) Study

Improving the treatment of trauma, a leading cause of death worldwide, is of great clinical and public health interest. This analysis introduces flexible statistical methods for estimating center-level effects on individual outcomes in the context of highly variable patient populations, such as those of the PRospective, Observational, Multi-center Major Trauma Transfusion study. Ten US level I trauma centers enrolled a total of 1,245 trauma patients who survived at least 30 minutes after admission and received at least one unit of red blood cells. Outcomes included death, multiple organ failure, substantial bleeding, and transfusion of blood products. The centers involved were classified as either large or small-volume based on the number of massive transfusion patients enrolled during the study period. We focused on estimation of parameters inspired by causal inference, specifically estimated impacts on patient outcomes related to the volume of the trauma hospital that treated them. We defined this association as the change in mean outcomes of interest that would be observed if, contrary to fact, subjects from large-volume sites were treated at small-volume sites (the effect of treatment among the treated). We estimated this parameter using three different methods, some of which use data-adaptive machine learning tools to derive the outcome models, minimizing residual confounding by reducing model misspecification. Differences between unadjusted and adjusted estimators sometimes differed dramatically, demonstrating the need to account for differences in patient characteristics in clinic comparisons. In addition, the estimators based on robust adjustment methods showed potential impacts of hospital volume. For instance, we estimated a survival benefit for patients who were treated at large-volume sites, which was not apparent in simpler, unadjusted comparisons. By removing arbitrary modeling decisions from the estimation process and concentrating on parameters that have more direct policy implications, these potentially automated approaches allow methodological standardization across similar comparativeness effectiveness studies.

Transfusion of plasma, platelets, and red blood cells in a 1:1:1 vs a 1:1:2 ratio and mortality in patients with severe trauma: the PROPPR randomized clinical trial

IMPORTANCE

Severely injured patients experiencing hemorrhagic shock often require massive transfusion. Earlier transfusion with higher blood product ratios (plasma, platelets, and red blood cells), defined as damage control resuscitation, has been associated with improved outcomes; however, there have been no large multicenter clinical trials.

OBJECTIVE

To determine the effectiveness and safety of transfusing patients with severe trauma and major bleeding using plasma, platelets, and red blood cells in a 1:1:1 ratio compared with a 1:1:2 ratio.

DESIGN, SETTING, AND PARTICIPANTS

Pragmatic, phase 3, multisite, randomized clinical trial of 680 severely injured patients who arrived at 1 of 12 level I trauma centers in North America directly from the scene and were predicted to require massive transfusion between August 2012 and December 2013.

INTERVENTIONS

Blood product ratios of 1:1:1 (338 patients) vs 1:1:2 (342 patients) during active resuscitation in addition to all local standard-of-care interventions (uncontrolled).

MAIN OUTCOMES AND MEASURES

Primary outcomes were 24-hour and 30-day all-cause mortality. Prespecified ancillary outcomes included time to hemostasis, blood product volumes transfused, complications, incidence of surgical procedures, and functional status.

RESULTS

No significant differences were detected in mortality at 24 hours (12.7% in 1:1:1 group vs 17.0% in 1:1:2 group; difference, -4.2% [95% CI, -9.6% to 1.1%]; P = .12) or at 30 days (22.4% vs 26.1%, respectively; difference, -3.7% [95% CI, -10.2% to 2.7%]; P = .26). Exsanguination, which was the predominant cause of death within the first 24 hours, was significantly decreased in the 1:1:1 group (9.2% vs 14.6% in 1:1:2 group; difference, -5.4% [95% CI, -10.4% to -0.5%]; P = .03). More patients in the 1:1:1 group achieved hemostasis than in the 1:1:2 group (86% vs 78%, respectively; P = .006). Despite the 1:1:1 group receiving more plasma (median of 7 U vs 5 U, P < .001) and platelets (12 U vs 6 U, P < .001) and similar amounts of red blood cells (9 U) over the first 24 hours, no differences between the 2 groups were found for the 23 prespecified complications, including acute respiratory distress syndrome, multiple organ failure, venous thromboembolism, sepsis, and transfusion-related complications.

CONCLUSIONS AND RELEVANCE

Among patients with severe trauma and major bleeding, early administration of plasma, platelets, and red blood cells in a 1:1:1 ratio compared with a 1:1:2 ratio did not result in significant differences in mortality at 24 hours or at 30 days. However, more patients in the 1:1:1 group achieved hemostasis and fewer experienced death due to exsanguination by 24 hours. Even though there was an increased use of plasma and platelets transfused in the 1:1:1 group, no other safety differences were identified between the 2 groups.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01545232.

Beyond emergency surgery: redefining acute care surgery

BACKGROUND

Considerable debate exists regarding the definition, skill set, and training requirements for the new specialty of acute care surgery (ACS). We hypothesized that a patient subset could be identified that requires a level of care beyond general surgical training and justifies creation of this new specialty.

MATERIALS AND METHODS

Reviewed patient admissions over 1-y to the only general surgical service at a level I trauma center-staffed by trauma and/or critical care trained physicians. Patients classified as follows: trauma, ACS, emergency general (EGS), or elective surgery. ACS patients are nonelective, nontrauma patients with significantly altered physiology requiring intensive care unit admission and/or specific complex operative interventions. Differences in demographics, hospital course, and outcomes were analyzed.

RESULTS

In-patient service evaluated approximately 5500 patients, including 3300 trauma patients. A total of 2152 admissions include 37% trauma, 30% elective, 28% EGS, and 4% ACS. ACS and trauma patients were more likely to require multiple operations (ACS relative risk [RR] = 11.5; trauma RR = 5.7, P < 0.0001), have longer hospital and intensive care unit length of stay, and higher mortality (P < 0.0001). They were less likely to be discharged home (ACS RR = 0.75; trauma RR = 0.67, P < 0.0001) compared with that of the EGS group. EGS and elective patients were most similar to each other in multiple areas.

CONCLUSIONS

ACS and EGS patients represent distinct patient cohorts, as reflected by significant differences in critical care needs, likelihood of multiple operations, and need for postdischarge rehabilitation. The skills required to care for ACS patients, including ability to rescue from complications and provide critical care, differ from those required for EGS patients and supports development of ACS training and regionalization of care.

Defining when to initiate massive transfusion: a validation study of individual massive transfusion triggers in PROMMTT patients

BACKGROUND

Early predictors of massive transfusion (MT) would prevent undertriage of patients likely to require MT. This study validates triggers using the Prospective Observational Multicenter Major Trauma Transfusion (PROMMTT) study.

METHODS

All enrolled patients in PROMMTT were analyzed. The initial emergency department value for each trigger (international normalized ratio [INR], systolic blood pressure, hemoglobin, base deficit, positive result for Focused Assessment for the Sonography of Trauma examination, heart rate, temperature, and penetrating injury mechanism) was compared for patients receiving MT (≥ 10 U of packed red blood cells in 24 hours) versus no MT. Adjusted odds ratios (ORs) for MT are reported using multiple logistic regression. If all triggers were known, a Massive Transfusion Score (MTS) was created, with 1 point assigned for each met trigger.

RESULTS

A total of 1,245 patients were prospectively enrolled with 297 receiving an MT. Data were available for all triggers in 66% of the patients including 67% of the MTs (199 of 297). INR was known in 87% (1,081 of 1,245). All triggers except penetrating injury mechanism and heart rate were valid individual predictors of MT, with INR as the most predictive (adjusted OR, 2.5; 95% confidence interval, 1.7-3.7). For those with all triggers known, a positive INR trigger was seen in 49% receiving MT. Patients with an MTS of less than 2 were unlikely to receive MT (negative predictive value, 89%). If any two triggers were present (MTS ≥ 2), sensitivity for predicting MT was 85%. MT was present in 33% with an MTS of 2 greater compared with 11% of those with MTS of less than 2 (OR, 3.9; 95% confidence interval, 2.6-5.8; p < 0.0005).

CONCLUSION

Parameters that can be obtained early in the initial emergency department evaluation are valid predictors for determining the likelihood of MT.

LEVEL OF EVIDENCE

Diagnostic, level II.

Payer status is associated with the use of prophylactic inferior vena cava filter in high-risk trauma patients

BACKGROUND

It is controversial whether patients at high risk for pulmonary embolism (PE) should receive prophylactic inferior vena cava filters (IVC) filters. This lack of clarity creates the potential for variability and disparities in care. We hypothesized there would be differential use of prophylactic IVC filters for patients at high risk for PE on the basis of insurance status.

METHODS

We performed a retrospective analysis using the National Trauma Databank (2002-2007). We included adult patients at high risk for PE (traumatic brain injury or spinal cord injury) and excluded patients with a diagnosis of deep venous thrombosis (DVT) or PE. Logistic regression was performed to control for confounders and a hierarchical mixed effects model was used to control for center.

RESULTS

A prophylactic filter was placed in 3,331 (4.3%) patients in the study cohort. Patients without insurance had an IVC filter placed less often compared with those with any form of insurance (2.7% vs 4.9%, respectively). After adjusting for confounders, we found that patients without insurance were less likely to receive a prophylactic IVC filter, even when we controlled for center (OR 5.3, P < .001).

CONCLUSION

When guidelines lack clarity, unconscious bias has the potential to create a system with different levels of care based on socioeconomic disparities.

How to read a review paper

Review papers commonly summarize the current knowledge on a selected topic. These types of papers are considered narrative reviews. Narrative reviews rarely detail the methods used to select the literature included, nor do the authors typically report the purpose of the review. Narrative reviews may be biased due to inadequate literature reviews or individual beliefs. A systematic review limits bias by disclosing the purpose of the paper, the assembly of the literature, and the appraisal of study quality. A meta-analysis, a specific style of systematic review, quantitatively pools data from individual studies for re-analysis. Pooling data increases the sample size and improves statistical power. The common representation of a meta-analysis is the forest plot. The forest plot demonstrates the odds ratio of individual studies, the weight each trial contributes to the analysis, and the 95% confidence intervals. Systematic reviews and meta-analyses are not without shortcomings, including issues related to study heterogeneity. Because of their transparency, systematic evaluations of the literature are superior to narrative reviews.

Clinical experience with Alloderm: A one-staged composite dermal/epidermal replacement utilizing processed cadaver dermis and thin autografts

Alloderm has been advocated for the management of acute burns. However, few studies have demonstrated the feasibility of this technique.

METHODS

We reviewed the medical records of all patients treated in our burn center who received Alloderm since 1999.

RESULTS

Alloderm was used in 21 burn patients and 6 patients with traumatic skin loss. The average size of Alloderm used in the burn patients was 517+/-144 cm(2) (range 24-3000 cm(2)). The average Alloderm thickness used was 0.008 in. and autografts were harvested at an average of 0.007 in. Overall, Alloderm was used in a variety of locations including the face in 3 patients (2 burns, 1 traumatic skin loss) and hands in 7 patients (6 burns, 1 traumatic skin loss). Successful take was observed in 26/27 patients.

CONCLUSIONS

Alloderm can be used successfully in patients with acute burns requiring grafting.

Shaping the future of surgery: the role of private regulation in determining quality standards

OBJECTIVE

To educate surgeons about the growth of the private regulatory movement and its potential implications for the practice of surgery.

METHODS

An in-depth analysis and literature review of one of the largest private regulatory groups, the Leapfrog Group, provides a model for understanding the impact of these groups on the practice of surgery. A detailed discussion of the history, mission, structure, and quality initiatives of Leapfrog is included.

RESULTS

Private regulatory groups are using quality standards as a method for controlling the rising cost of health care. Traditionally, little financial support, manpower, or incentives have existed for individual surgeons and hospitals to report and maintain their own outcomes data. However, as surgical outcomes have increasingly become the target of quality improvement initiatives, the need to measure performance is gaining importance. Surgical quality has been both a direct target of private regulation, as illustrated by the evidence-based hospital referral guidelines of Leapfrog, and an indirect target with initiatives like computerized physician order entry and ICU staffing guidelines.

CONCLUSIONS

Private regulation is rapidly reshaping the way we practice and teach surgery. It is almost a certainty that their power, popularity, financial support, and missions will all continue to expand. As surgeons, we must decide soon if we wish to be an active participant in shaping the movement or, rather, if we are going to let it shape us by remaining largely uninvolved.

Does academic advancement impact teaching performance of surgical faculty?

BACKGROUND

An important reason for young surgeons entering academic practice is to educate trainees. As clinical and administrative responsibility increases, teaching time is decreased. We attempted to determine if the teaching performance of surgeons declines with career advancement.

METHODS

Between July 1998 and June 2002, all faculty at our institution were evaluated by medical students on the surgical clerkship. Surgeons were scored on clinical teaching (CLINIC), operating room teaching (OR), and overall teaching (ALL) with the use of a 4-point scale. Surgeons were grouped by years in practice; group scores were compared with ANOVA.

RESULTS

A total of 6345 evaluations were completed on 74 academic surgeons. Junior surgeons (< or = 5 years) performed better in operating room teaching (P < .001), clinical teaching (P<.001), and overall teaching (P < .001) compared with those in practice more than 5 years. When junior surgeons were compared with the most senior faculty (> or = 15 years), the difference in all categories was even greater (P < .001). Tenure status had no relationship to teaching ability.

CONCLUSIONS

Junior faculty surgeons were perceived to be more effective teachers when compared to senior faculty. With career advancement, faculty may devote less energy to teaching and become less effective. Therefore, continued emphasis should be placed on strengthening education skills throughout the surgical career.

The utility of frozen section evaluation for follicular thyroid lesions

BACKGROUND

Because fine-needle aspiration cannot reliably discriminate between benign and malignant follicular thyroid lesions, some surgeons use intraoperative frozen section (FS) to guide operative management. To determine the utility of FS for these lesions, we reviewed our institutional experience.

METHODS

Between 1994 and 2001, 152 patients underwent surgical resection for follicular neoplasms.

RESULTS

The mean age of the patients was 47 years, and 76% were female. Forty-one (32%) FSs were reported as benign, 5 (4%) as malignant, and 3 (2%) as indeterminate, and in 80 (62%), the diagnosis was "follicular lesion, deferred to permanent histology." On paraffin section, all patients with malignant FSs had thyroid cancer, and all 41 patients with benign FSs had benign lesions. Thus, FS for diagnosis of follicular thyroid cancer had a sensitivity, specificity, positive predictive value, and accuracy of 67%, 100%, 100%, and 96%, respectively. In most cases (64%), FS rendered no additional information at the time of operation. Therefore, the cost per useful FS was $7800, which is higher than the charge of a completion thyroidectomy (approximately $6000).

CONCLUSIONS

FS analysis for follicular lesions seems to be highly specific and accurate. However, because of the low sensitivity, routine use of FS is not cost-effective in patients with follicular thyroid lesions.