Tube Thoracostomy Management in the Combat Wounded

The intent of this study was to characterize the management and subsequent complications of combat injury tube thoracostomies and to determine risk factors for the development of pneumonia (PNA) and retained hemothorax (RH). One hundred fifteen patients with 173 tube thoracostomies met the inclusion criteria and were analyzed. The mean injury severity score was 30.8 + 11.6, 23.5 per cent had traumatic amputations, 49.7 per cent had a hemothorax, and 50.3 per cent had a pneumothorax as indications for tube thoracostomy (TT) placement. Within 24 hours of injury, 89.6 per cent were intubated, the majority (54%) were injured by improvised explosive devices, 35.6 per cent sustained rib fractures, and 12.2 per cent had a diaphragm injury. A mean of 1.5 + 0.7(range 1-4) tube thoracostomies were placed, 18.3 per cent of patients had bilateral tube thoracostomies, and the average TT duration was 6.7 + 3.9 days. The incidence of PNA was 27 per cent (n = 31), RH was 9.6 per cent (n = 11), and empyema was 1.7 per cent (n = 2). Multivariable analysis identified the duration of ventilation [OR 1.2, 95% confidence interval (CI): 1.097-1.313, P < 0.001] as independently associated with the development of PNA. Bilateral TT placement (OR 3.848, 95% CI: 1.219-12.143, P = 0.0216) and injury severity score (OR 1.050, 95% CI: 1.001-1.102, P = 0.0443) were independently associated with PNA development when a patient was intubated for eight days or less. The number of tube thoracostomies placed (OR 3.08, 95% CI: 1.03-9.18, P = 0.0439) was independently associated with the development of RH. Further research is warranted to identify modifiable risk factors to reduce the incidence of PNA and RH in patients with TT placed for traumatic injuries.

Development of an emergency general surgery process improvement program

BACKGROUND

The Joint Trauma System has demonstrated improved outcomes through coordinated research and process improvement programs. With fewer combat trauma patients, our military American College of Surgeons level 2 trauma center's ability to maintain a strong trauma Process Improvement (PI) program has become difficult. As emergency general surgery (EGS) patients are similar to trauma patients, our Trauma and Acute Care Surgery (TACS) service developed an EGS PI program analogous to what is done in trauma. We describe the implementation of our novel EGS PI program and its effect on institutional PI proficiency.

METHODS

An EGS registry was developed in 2013. Inclusion criteria were based on AAST published literature. In 2015, EGS registrar and PI coordinator positions were developed and filled with existing trauma staff. A formal EGS PI program began January 1, 2016. Pre- and post-program data was compared to determine the effect including EGS PI events had on increasing yield into our trauma PI program.

RESULTS

In 2016, TACS saw 1001 EGS consults. Four hundred forty-four met criteria for registry inclusion. Eighty-two patients had 131 PI events; re-admission within 30 days, unplanned therapeutic intervention, and unplanned ICU admission were the most common events. Capture of EGS PI events yielded a 49% increase compared with 2015.

CONCLUSION

Overall patient volume and PI events post EGS PI program initiation exceeded those prior to implementation. These data suggest that extending trauma PI principles to EGS may be beneficial in maintaining inter-war military and/or lower volume trauma center readiness.

Assessing Risk and Related Complications after Reversal of Combat-Associated Ostomies

BACKGROUND

During the past decade of conflict, numerous patients with combat-associated injuries required the formation of an ostomy. However, outcomes in those patients undergoing ostomy reversal have yet to be analyzed. We review the experience and identify risk factors for complications after ostomy reversal in a series of patients with combat injuries at our military treatment facility.

STUDY DESIGN

A retrospective review of patients with combat-associated injuries managed with a diverting ostomy who underwent ostomy reversal at our military treatment facility during a 13-year period. Demographic and clinical data were collected for all patients and postoperative complications were identified. Multivariate analysis was performed to identify independent risk factors for complications after reversal. Complication rates were calculated for 90-day periods of time after ostomy creation and best-fit curve analysis was conducted.

RESULTS

Ninety-nine patients were identified who underwent ostomy reversal. Forty patients (40.4%) suffered a post-reversal complication. On multivariate analysis, older age (odds ratio 1.11/y; p = 0.038), severe perineal injury indication for diversion (odds ratio 4.37; p = 0.028), and increased time interval between ostomy creation and reversal (odds ratio 1.005/d; p = 0.037), were independently associated with postoperative complications. A cubic regression best fit quarterly complication rate data (R² 0.526; p < 0.001) and calculates a minimum complication rate for reversal 90 to 180 days after ostomy creation.

CONCLUSIONS

Ostomy reversal in patients wounded in combat is a major undertaking with a high complication rate. The finding of a shorter interval from ostomy creation to reversal independently associated with a reduction in complications provides a modifiable risk factor to guide future practice and potentially reduce complications. Our modeling suggests reversal in the 3- to 6-month time frame can have the lowest rate of complications. Future research to reduce complications is indicated, especially in older patients with perineal wounds.

Primary Pulmonary Thrombus in Combat Casualties: Is Treatment Necessary?

The objective of this study was to describe the natural history of primary pulmonary thrombus (PPT) in combat casualties. This was a retrospective study of casualties treated at a major military treatment facility from 2010 to 2012. Patients with a downrange chest CT were included. CTs were reviewed by two independent, blinded radiologists to confirm PPT on initial imaging. Follow-up CTs, if obtained, were also independently reviewed to determine the extent of clot burden. Two hundred and forty-nine casualties with a downrange, acceptable quality chest CT were included. 9 per cent (23/249) of patients sustained PPT. Thirty nine per cent (9/23) were initially treated with therapeutic anticoagulation (AC). Conversely, 61 per cent (14/23) arrived to our military treatment facility without AC. Seven arriving without AC-developed pulmonary symptoms during their hospitalization and had interval chest CTs. Of those, three had no evidence of pulmonary thrombus. The other four had subsegmental filling defects and three were started AC whereas one had an IVC (Inferior Vena Cava) filter inserted. In total, 11/23 (48%) PPT patients were managed without AC and discharged without complications. This is the first study attempting to look at PPT natural history. There were no adverse sequelae from managing PPT without AC. Further studies are warranted to further characterize PPT.

Primary Pulmonary Thrombus in Combat Casualties: Is Treatment Necessary?

The objective of this study was to describe the natural history of primary pulmonary thrombus (PPT) in combat casualties. This was a retrospective study of casualties treated at a major military treatment facility from 2010 to 2012. Patients with a downrange chest CTwere included. CTs were reviewed by two independent, blinded radiologists to confirm PPTon initial imaging. Follow-up CTs, if obtained, were also independently reviewed to determine the extent of clot burden. Two hundred and forty-nine casualties with a downrange, acceptable quality chest CT were included. 9 per cent (23/249) of patients sustained PPT. Thirty nine per cent (9/23) were initially treated with therapeutic anticoagulation (AC). Conversely, 61 per cent (14/23) arrived to our military treatment facility without AC. Seven arriving without AC-developed pulmonary symptoms during their hospitalization and had interval chest CTs. Of those, three had no evidence of pulmonary thrombus. The other four had subsegmental filling defects and three were started AC whereas one had an IVC (Inferior Vena Cava) filter inserted. In total, 11/23 (48%) PPT patients were managed without AC and discharged without complications. This is the first study attempting to look at PPT natural history. There were no adverse sequelae from managing PPT without AC. Further studies are warranted to further characterize PPT.

The impact of septic stimuli on the systemic inflammatory response and physiologic insult in a preclinical non-human primate model of polytraumatic injury

Background

Established animal trauma models are limited in recapitulating the pathophysiology of human traumatic injury. Herein, we characterize the physiologic insult and inflammatory response in two clinically relevant non-human primate (NHP) trauma models.

Methods

Mauritian Cynomolgus Macaques underwent either a laparoscopic closed abdomen liver injury (laparoscopic 60% left-lobe hepatectomy) in an established uncontrolled severe hemorrhage model (THM), or a polytrauma hemorrhage model (PHM) involving combined liver and bowel injury, uncontrolled severe hemorrhage as well as an open full-thickness cutaneous flank wound. Fixed volume resuscitation strategies were employed in the THM and goal directed resuscitation was used in the PHM. Complete peripheral blood and critical clinical chemistry parameters, serum biomarkers of systemic inflammation, tissue perfusion parameters, as well as survival, were compared between the models throughout the 2-week study period.

Results

NHPs in both the THM (n = 7) and the PHM (n = 21) demonstrated tissue hypoperfusion (peak lactate 6.3 ± 0.71 mmol/L) with end organ injury (peak creatinine 3.08 ± 0.69 mg/dL) from a similar liver injury (60% left hemi-hepatectomy), though the PHM NHPs had a significantly higher blood loss (68.1% ± 12.7% vs. 34.3% ± 2.3%, p = 0.02), lower platelet counts (59 ± 25 vs. 205 ± 46 K/uL, p = 0.03) and a trend towards higher mortality (90.5% vs. 33.3%, p = 0.09). The inflammatory response was robust in both models with peak cytokine (IL-6 > 6000-fold above baseline) and peak leukocyte values (WBC 27 K/uL) typically occurring around t = 240 min from the time of hepatic injury. A more robust systemic inflammatory response was appreciated in the PHM resulting in marked elevations in peak serum IL-6 (7887 ± 2521 pg/mL vs.1076 ± 4833 pg/mL, p = 0.02), IL-1ra (34,499 ± 5987 pg/mL vs. 2511 ± 1228 pg/mL, p < 0.00), and IL-10 (13,411 pg/mL ± 5598 pg/mL vs. 617 pg/mL ± 252 pg/mL, p = 0.03).

Conclusion

This comparative analysis provides a unique longitudinal perspective on the post-injury inflammatory response in two clinically relevant models, and demonstrates that the addition of septic stimuli to solid organ injury increases both the hemorrhagic insult and inflammatory response.

Trauma induced heterotopic ossification patient serum alters mitogen activated protein kinase signaling in adipose stem cells

Post-traumatic heterotopic ossification (HO) is the formation of ectopic bone in non-osseous structures following injury. The precise mechanism for bone development following trauma is unknown; however, early onset of HO may involve the production of pro-osteogenic serum factors. Here we evaluated serum from a cohort of civilian and military patients post trauma to determine early induction gene signatures in orthopaedic trauma induced HO. To test this, human adipose derived stromal/stem cells (hASCs) were stimulated with human serum from patients who developed HO following trauma and evaluated for a gene panel with qPCR. Pathway gene analysis ontology revealed that hASCs stimulated with serum from patients who developed HO had altered gene expression in the activator protein 1 (AP1) and AP1 transcriptional targets pathways. Notably, there was a significant repression in FOS gene expression in hASCs treated with serum from individuals with HO. Furthermore, the mitogen-activated protein kinase (MAPK) signaling pathway was activated in hASCs following serum exposure from individuals with HO. Serum from both military and civilian patients with trauma induced HO had elevated downstream genes associated with the MAPK pathways. Stimulation of hASCs with known regulators of osteogenesis (BMP2, IL6, Forskolin, and WNT3A) failed to recapitulate the gene signature observed in hASCs following serum stimulation, suggesting non-canonical mechanisms for gene regulation in trauma induced HO. These findings provide new insight for the development of HO and support ongoing work linking the systemic response to injury with wound specific outcomes.

Diagnostic Bacteriology: Raman Spectroscopy

Current clinical methodology for identification of bacterial infections relies predominantly on culturing microbes from patient material and performing biochemical tests. This can often be an inefficient and lengthy process, which has a significant detrimental effect upon patient care. Techniques used in other aspects of molecular research have the potential to revolutionize the way in which diagnostic tests are used and delivered in the clinical setting. The need for rapid, accurate, and cost-effective molecular techniques in the diagnostic laboratory is imperative to improving patient care, preventing the spread of drug resistance and decreasing the overall burden associated with nosocomial infections. Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS) are powerful vibrational spectroscopy techniques that are being developed for highly sensitive pathogen identification in complex clinical samples. Raman spectroscopy is a molecular technique that is capable of probing samples noninvasively and nondestructively. It has been used with high specificity to assess tissue and bacterial samples at the molecular level with diverse clinical and diagnostic applications. SERS has recently developed out of the advances in the Raman spectroscopy arena. This technique is designed to amplify Raman scattering and allows for better differentiation of bacterial isolates. Although the current parameters for the use of SERS require a pure culture and are relatively monoparametric, current breakthroughs and testing are pushing the technology to new levels and thus changing the face of modern bacterial diagnostics.

Maintaining Quality in Lower Volume Cardiac Surgery: A Blueprint From a Military Program

Although there is a clear volume-outcome relationship in the field of cardiac surgery, the existence of high-performing programs with relatively low case volumes is well established. This report describes the programmatic and institutional processes in place at a lower volume cardiac surgery center in a US military hospital, which have been executed to optimally leverage available resources in the delivery of exemplary patient care. By implementing a highly collaborative practice, rigorous outcomes review, evidence-based standardized care pathways, consistent attending surgeon oversight for care delivery, careful case selection, and a mechanism for support from highly experienced outside cardiac surgeons, the cardiac surgery program at the authors' institution delivers care on par with its higher volume counterparts. A review of these practices and available supporting evidence may provide a model for other programs seeking success in this setting.

Host responses to concurrent combined injuries in non-human primates

Background

Multi-organ failure (MOF) following trauma remains a significant cause of morbidity and mortality related to a poorly understood abnormal inflammatory response. We characterized the inflammatory response in a non-human primate soft tissue injury and closed abdomen hemorrhage and sepsis model developed to assess realistic injury patterns and induce MOF.

Methods

Adult male Mauritan Cynomolgus Macaques underwent laparoscopy to create a cecal perforation and non-anatomic liver resection along with a full-thickness flank soft tissue injury. Treatment consisted of a pre-hospital phase followed by a hospital phase after 120 minutes. Blood counts, chemistries, and cytokines/chemokines were measured throughout the study. Lung tissue inflammation/apoptosis was confirmed by mRNA quantitative real-time PCR (qPCR), H&E, myeloperoxidase (MPO) and TUNEL staining was performed comparing age-matched uninjured controls to experimental animals.

Results

Twenty-one animals underwent the protocol. Mean percent hepatectomy was 64.4 ± 5.6; percent blood loss was 69.0 ± 12.1. Clinical evidence of end-organ damage was reflected by a significant elevation in creatinine (1.1 ± 0.03 vs. 1.9 ± 0.4, p=0.026). Significant increases in systemic levels of IL-10, IL-1ra, IL-6, G-CSF, and MCP-1 occurred (11-2986-fold) by 240 minutes. Excessive pulmonary inflammation was evidenced by alveolar edema, congestion, and wall thickening (H&E staining). Concordantly, amplified accumulation of MPO leukocytes and significant pulmonary inflammation and pneumocyte apoptosis (TUNEL) was confirmed using qRT-PCR.

Conclusion

We created a clinically relevant large animal multi-trauma model using laparoscopy that resulted in a significant systemic inflammatory response and MOF. With this model, we anticipate studying systemic inflammation and testing innovative therapeutic options.

Local host level of cytokines and gene expression are associated with successful healing of combat-related extremity wounds with persistent critical colonization

Persistent critical colonization (CC) may lead to wound healing failure (WF) despite antibiotic treatment. We investigated the local host gene expression and cytokine response of critically colonized wounds to identify early signs of WF.

Seventy-three patients with combat-related extremity wounds requiring serial operative debridements were assessed to determine whether there was an association between CC and WF. A total of 116wounds were identified. A subset of 44% (51/116) of these wounds developed CC (considered as growth of 105 bacterial CFU/g of tissue or μL of wound effluent). Samples were collected at each debridement and tested for 32 cytokines and 192 genes associated with wound healing. A two-tailed alpha &lt; 0.05 was considered statistically significant.

Wounds closed with CC had increased odds of failing to heal OR=3.3 (1.225 to 8.9). A. baumannii was the most commonly isolated species. A subset of 12 out of 51 (24%) wounds which developed CC, failed. Of those, 10 had CC present on day of wound closure. However, 10 additional wounds with CC present at time of closure healed successfully after a similar number of debridements. Comparing these wounds, WF was associated with a decrease in the level of EGF (p&lt;0.05) and lower gene expression of IFNB1 (p=0.01), FGF-8 (p=0.01) and HMGB1 (p=0.01). Successful healing was associated with an increase in the level of VEGF (p&lt;0.01).

Resolution of persistent CC before closure may prevent failure. Local host gene expression and cytokine response may provide additional insight for successful closure. Further studies investigating microbiology data and possible antibiotic resistant genes are needed.

Nucleic acid scavenging microfiber mesh inhibits trauma-induced inflammation and thrombosis

Trauma patients produce a host of danger signals and high levels of damage-associated molecular patterns (DAMPs) after cellular injury and tissue damage. These DAMPs are directly and indirectly involved in the pathogenesis of various inflammatory and thrombotic complications in patients with severe injuries. No effective therapeutic agents for the removal of DAMPs from blood or tissue fluid have been developed. Herein, we demonstrated that nucleic acid binding polymers, e.g., polyethylenimine (PEI) and polyamidoamine dendrimers, immobilized onto electrospun microfiber mesh can effectively capture various DAMPs, such as extracellular DNAs and high mobility group box 1 (HMGB1). Furthermore, treatment with PEI-immobilized microfiber mesh abrogated the ability of DAMPs, released from dead and dying cells in culture or found in patients following traumatic injury, to activate innate immune responses and coagulation in vitro and in vivo. Nucleic acid scavenging microfiber meshes represent an effective strategy to combat inflammation and thrombosis in trauma.

Nonsteroidal anti-inflammatory drugs may affect cytokine response and benefit healing of combat-related extremity wounds

BACKGROUND

After adequate operative debridement and antimicrobial therapies, combat-related extremity wounds that either heal or fail are both associated with a distinct inflammatory response. Short-term use of nonsteroidal anti-inflammatory drugs in postoperative pain management may affect this response and, by consequence, the healing potential of these wounds. We investigated whether patients treated with nonsteroidal anti-inflammatory drugs had a distinct inflammatory response; different rates of critical colonization, defined as >10⁵ colony forming units on quantitative bacteriology; and healing potential.

METHODS

We retrospectively reviewed the records of 73 patients with combat-related extremity wounds. Patients were separated into 2 groups: those who received nonsteroidal anti-inflammatory drugs during the debridement period (nonsteroidal anti-inflammatory drugs group, N = 17) and those who did not (control group; N = 56). Serum and wound tissue samples collected during each operative debridement were measured for 32 known cytokines and tested for quantitative bacteriology, respectively. We compared cytokine concentrations between groups and then designed a logistic regression model to identify variables associated with successful wound healing, while controlling for known confounders.

RESULTS

Despite similar demographics and wound characteristics, the nonsteroidal anti-inflammatory drugs group had significant lesser concentrations of inflammatory cytokines, interleukin-2, interleukin-6, interleukin-8, and monocyte chemoattractant protein-1. On multivariate analysis, nonsteroidal anti-inflammatory drug treatment emerged as a predictor of successful wound healing after controlling for known confounders such as wound size, tobacco use, Acute Physiology and Chronic Health Evaluation II score, and critical colonization.

CONCLUSION

Treatment with nonsteroidal anti-inflammatory drugs for postoperative pain management after major combat-related extremity trauma is associated with lesser concentrations of inflammatory cytokines and may contribute to a more favorable inflammatory response leading to successful wound healing.

Burned to the bone

Heterotopic ossification--a complication of severe burns, head or blast injuries, and orthopaedic trauma--can result from altered adenosine metabolism in mesenchymal stem cells in response to elevated extracellular ATP (Peterson et al., this issue).

Preventing Heterotopic Ossification in Combat Casualties-Which Models Are Best Suited for Clinical Use?

BACKGROUND

To prevent symptomatic heterotopic ossification (HO) and guide primary prophylaxis in patients with combat wounds, physicians require risk stratification methods that can be used early in the postinjury period. There are no validated models to help guide clinicians in the treatment for this common and potentially disabling condition.

QUESTIONS/PURPOSES

We developed three prognostic models designed to estimate the likelihood of wound-specific HO formation and compared them using receiver operating characteristic (ROC) curve analysis and decision curve analysis (DCA) to determine (1) which model is most accurate; and (2) which technique is best suited for clinical use.

METHODS

We obtained muscle biopsies from 87 combat wounds during the first débridement in the United States, all of which were evaluated radiographically for development of HO at a minimum of 2 months postinjury. The criterion for determining the presence of HO was the ability to see radiographic evidence of ectopic bone formation within the zone of injury. We then quantified relative gene expression from 190 wound healing, osteogenic, and vascular genes. Using these data, we developed an Artificial Neural Network, Random Forest, and a Least Absolute Shrinkage and Selection Operator (LASSO) Logistic Regression model designed to estimate the likelihood of eventual wound-specific HO formation. HO was defined as any HO visible on the plain film within the zone of injury. We compared the models accuracy using area under the ROC curve (area under the curve [AUC]) as well as DCA to determine which model, if any, was better suited for clinical use. In general, the AUC compares models based solely on accuracy, whereas DCA compares their clinical utility after weighing the consequences of under- or overtreatment of a particular disorder.

RESULTS

Both the Artificial Neural Network and the LASSO logistic regression models were relatively accurate with AUCs of 0.78 (95% confidence interval [CI], 0.72-0.83) and 0.75 (95% CI, 0.71-0.78), respectively. The Random Forest model returned an AUC of only 0.53 (95% CI, 0.48-0.59), marginally better than chance alone. Using DCA, the Artificial Neural Network model demonstrated the highest net benefit over the broadest range of threshold probabilities, indicating that it is perhaps better suited for clinical use than the LASSO logistic regression model. Specifically, if only patients with greater than 25% risk of developing HO received prophylaxis, for every 100 patients, use of the Artificial Network Model would result in six fewer patients who unnecessarily receive prophylaxis compared with using the LASSO regression model while not missing any patients who might benefit from it.

CONCLUSIONS

Our findings suggest that it is possible to risk-stratify combat wounds with regard to eventual HO formation early in the débridement process. Using these data, the Artificial Neural Network model may lead to better patient selection when compared with the LASSO logistic regression approach. Future prospective studies are necessary to validate these findings while focusing on symptomatic HO as the endpoint of interest.

LEVEL OF EVIDENCE

Level III, prognostic study.

Lessons of War: Turning Data Into Decisions

Background

Recent conflicts in Afghanistan and Iraq produced a substantial number of critically wounded service-members. We collected biomarker and clinical information from 73 patients who sustained 116 life-threatening combat wounds, and sought to determine if the data could be used to predict the likelihood of wound failure.

Methods

From each patient, we collected clinical information, serum, wound effluent, and tissue prior to and at each surgical débridement. Inflammatory cytokines were quantified in both the serum and effluent, as were gene expression targets. The primary outcome was successful wound healing. Computer intensive methods were used to derive prognostic models that were internally validated using target shuffling and cross-validation methods. A second cohort of eighteen critically injured civilian patients was evaluated to determine if similar inflammatory responses were observed.

Findings

The best-performing models enhanced clinical observation with biomarker data from the serum and wound effluent, an indicator that systemic inflammatory conditions contribute to local wound failure. A Random Forest model containing ten variables demonstrated the highest accuracy (AUC 0.79). Decision Curve Analysis indicated that the use of this model would improve clinical outcomes and reduce unnecessary surgical procedures. Civilian trauma patients demonstrated similar inflammatory responses and an equivalent wound failure rate, indicating that the model may be generalizable to civilian settings.

Interpretation

Using advanced analytics, we successfully codified clinical and biomarker data from combat patients into a potentially generalizable decision support tool. Analysis of inflammatory data from critically ill patients with acute injury may inform decision-making to improve clinical outcomes and reduce healthcare costs.

Funding

United States Department of Defense Health Programs.

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We analyzed biomarker and clinical data to predict the likelihood of wound failure.

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We found that systematic inflammatory conditions contribute to local wound failure.

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This response is comparable between combat wounded and civilian patients.

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This response can be measured and translated into clinical decision support tools.

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These predictive models will benefit both military and civilian health systems.