Predicting factors for extremity fracture among border-fall patients using machine learning computing.

Background: The factors causing the injuries sustained from falls at US-Mexican border include falls from border wall or fence, fleeing from border patrols, ejecting from vehicle, and others. This study aimed to determine the factors leading to anatomical injuries and to identify the importance of factors leading to limb fracture and internal organ injuries. Methods: A total of 178 patients who sustained musculoskeletal injuries or internal organ injuries and were admitted to our hospital were included in this retrospective study. Factors indexed for analysis included demographics, comorbidities, and falling mechanic factors. Correlations between anatomical injuries and mechanical injuries were analyzed. Multilayer perceptron neural network (MPNN) was used to identify predictive factors and to stratify the importance of these factors leading to injuries. The SPSS software was used for statistical analysis and predictive factor analysis. Results: The extremity fracture was associated with border wall/fence fall (p = 0.001) and fleeing (p = 0.002). The spine fracture was correlated with bridge jump/fall (p = 0.007), fence jump/fall (p = 0.026). The vehicle ejecting/MVA was correlated with head injury (P < 0.001), chest injury (P < 0.001), and abdominal injury p < 0.001). MNPP stratify the importance of factor causing injury with multiple factor considered. Conclusion: The various injury factors caused different anatomical injuries. Multifactorial assessment associated with these injuries can improve the accuracy of diagnosis and develop a predictive model for clinical applications.

Outcomes of patients with traumatic brain injury after stress ulcer prophylaxis: a retrospective multicenter study.

Background: Stress ulcers in patients with traumatic brain injury (TBI) and spinal cord injury (SCI) present significant morbidity and mortality risks. Despite the low reported stress ulcer rates, stress ulcer prophylaxis (SUP) is widely administered in neurocritical care. It was hypothesized that universal SUP administration may not be associated with reduced rates of complications across all neurocritical care patients. Methods: This retrospective study encompassed neurocritical care patients aged ≥18 with moderate or severe TBI or SCI, admitted to the intensive care unit (ICU) between October 2020 and September 2021, across six level I trauma centers. Exclusions included patients with an ICU stay <2 days, prior SUP medication use, and pre-existing SUP diagnoses. The primary exposure was SUP, with the primary outcome being clinically significant gastrointestinal bleeds (CSGIBs). Secondary outcomes included pneumonia and in-hospital mortality. Patients were stratified by admission Glasgow Coma Scale (GCS) groups. Results: Among 407 patients, 83% received SUP, primarily H2 receptor antagonists (88%) and proton pump inhibitors (12%). Patients on SUP were significantly younger, had lower admission GCS scores, higher Injury Severity Scores, longer ICU stays, and higher rates of mechanical ventilation than non-SUP patients. Overall, CSGIBs were rare (1%) and not significantly different between the SUP and non-SUP groups (p=0.06). However, CSGIBs exclusively occurred in patients with GCS scores of 3-8, and SUP was associated with a significantly lower rate of CSGIBs in this subgroup (p=0.03). SUP was also linked to significantly higher pneumonia rates in both GCS 3-8 and GCS 9-12 patients. Conclusions: This study highlights the low incidence of CSGIBs in neurocritical trauma patients and suggests potential benefits of SUP, particularly for those with severe neurological impairment. Nevertheless, the increased risk of pneumonia associated with SUP in these patients warrants caution. Further research is crucial to refine SUP guidelines for neurocritical care patients and inform optimal strategies. Level of evidence: Level III, retrospective.

Operative Management Improves Near-term Survival of Patients With Odontoid Type II Fractures: A Propensity-matched National Registry Analysis.

STUDY DESIGN: National Trauma Data Bank (NTDB) review and propensity-matched analysis. OBJECTIVE: To evaluate differences in clinical outcomes by operative management. SUMMARY OF BACKGROUND DATA: Odontoid type II fractures are the most prevalent cervical fracture. Operative intervention on these fractures is frequently debated; surgical risks are compounded by clinical severity, patient age, and comorbidities. METHODS: This registry review included index admissions for odontoid type II fractures [International Classification of Diseases (ICD)-10 codes beginning with S12.11] from 1/1/2017 to 1/1/2020; patients who died in the emergency department (ED) were excluded. Propensity score techniques were used to match patients 1:1 by surgical management, using a caliper distance of 0.05, after matching on the following covariates that differed significantly between surgical and nonsurgical patients: age, sex, race, cause of injury, transfer status, injury severity score, ED Glasgow coma score, ED systolic blood pressure, presence of transverse ligamentous injury, cervical dislocation, and 8 comorbidities. The following outcomes were analyzed with McNemar tests and Wilcoxon signed-rank tests: near-term survival (discharged from the hospital to locations other than morgue or hospice), intensive care unit (ICU) admission, hospital complications, median hospital length of stay (LOS), and median ICU LOS. RESULTS: There were 16,607 patients, 2916 (17.6%) were operatively managed and 13,691 were nonoperatively managed. Before matching, survival was greater for patients managed operatively compared with nonoperatively (95.0% vs. 88.2%). The matched population consisted of 5334 patients: 2667 patients in the operative group (91.5% of this population) and 2667 well-matched patients in the nonoperative group. After matching, there was a survival benefit for patients who were operatively managed compared with nonoperative management (94.8% vs. 91.4% P <0.001). However, operative management was associated with greater development of complications, ICU admission, and longer hospital and ICU LOS. CONCLUSION: Compared with nonoperative management, operative management demonstrated a significant near-term survival benefit for patients with odontoid type II fractures in select patients. LEVEL OF EVIDENCE: III.

The relapsed acute lymphoblastic leukemia network (ReALLNet): a multidisciplinary project from the spanish society of pediatric hematology and oncology (SEHOP).

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer, with survival rates exceeding 85%. However, 15% of patients will relapse; consequently, their survival rates decrease to below 50%. Therefore, several research and innovation studies are focusing on pediatric relapsed or refractory ALL (R/R ALL). Driven by this context and following the European strategic plan to implement precision medicine equitably, the Relapsed ALL Network (ReALLNet) was launched under the umbrella of SEHOP in 2021, aiming to connect bedside patient care with expert groups in R/R ALL in an interdisciplinary and multicentric network. To achieve this objective, a board consisting of experts in diagnosis, management, preclinical research, and clinical trials has been established. The requirements of treatment centers have been evaluated, and the available oncogenomic and functional study resources have been assessed and organized. A shipping platform has been developed to process samples requiring study derivation, and an integrated diagnostic committee has been established to report results. These biological data, as well as patient outcomes, are collected in a national registry. Additionally, samples from all patients are stored in a biobank. This comprehensive repository of data and samples is expected to foster an environment where preclinical researchers and data scientists can seek to meet the complex needs of this challenging population. This proof of concept aims to demonstrate that a network-based organization, such as that embodied by ReALLNet, provides the ideal niche for the equitable and efficient implementation of "what's next" in the management of children with R/R ALL.

How do we PI? Results of an EAST quality, patient safety, and outcomes survey.

Background: Quality improvement is a cornerstone for any verified trauma center. Conducting effective quality and performance improvement, however, remains a challenge. In this study, we sought to better explore the landscape and challenges facing the members of the Eastern Association for the Surgery of Trauma (EAST) through a survey. Methods: A survey was designed by the EAST Quality Patient Safety and Outcomes Committee. It was reviewed by the EAST Research and Scholarship Committee and then distributed to 2511 EAST members. The questions were designed to understand the frequency, content, and perceptions surrounding quality improvement processes. Results: There were 151 respondents of the 2511 surveys sent (6.0%). The majority were trauma faculty (55%) or trauma medical directors (TMDs) (37%) at American College of Surgeons level I (62%) or II (17%) trauma centers. We found a wide variety of resources being used across hospitals with the majority of cases being identified by a TMD or attending (81%) for a multidisciplinary peer review (70.2%). There was a statistically significant difference in the perception of the effectiveness of the quality improvement process with TMDs being more likely to describe their process as moderately or very effective compared with their peers (77.5% vs. 57.7%, p=0.026). The 'Just Culture' model appeared to have a positive effect on the process improvement environment, with providers less likely to report a non-conducive environment (10.9% vs. 27.6%, p=0.012) and less feelings of assigning blame (3.1% vs. 13.8%, p=0.026). Conclusion: Case review remains an essential but challenging process. Our survey reveals a need to continue to advocate for appropriate time and resources to conduct strong quality improvement processes. Level of evidence: Epidemiological study, level III.

Epidemiology of C2 fractures and determinants of surgical management: analysis of a national registry.

Objective: Operative management of axis fractures (C2) usually depend on the stability and location of the break and individual patient characteristics. We sought to describe the epidemiology of C2 fractures and hypothesized that determinants for surgery would differ by fracture diagnosis. Methods: Patients with C2 fractures were identified from the US National Trauma Data Bank from January 1, 2017, to January 1, 2020. Patients were classified by C2 fracture diagnosis: odontoid type II, odontoid types I and III, and non-odontoid fracture (hangman's fracture or fractures through base of the axis). The primary comparison was C2 fracture surgery versus non-operative management. Multivariate logistic regression was used to identify independent associations with surgery. Decision tree-based models were developed to identify determinants for surgery. Results: There were 38 080 patients; 42.7% had an odontoid type II fracture; 16.5% had an odontoid type I/III fracture; and 40.8% had a non-odontoid fracture. All examined patient demographics, clinical characteristics, outcomes, and interventions differed by C2 fracture diagnosis. Overall, 5292 (13.9%) were surgically managed (17.5% odontoid type II, 11.0% odontoid type I/III, and 11.2% non-odontoid; p<0.001). The following covariates increased odds of surgery for all three fracture diagnoses: younger age, treatment at a level I trauma center, fracture displacement, cervical ligament sprain, and cervical subluxation. Determinants of surgery differed by fracture diagnosis: for odontoid type II, age ≤80 years, a displaced fracture, and cervical ligament sprain were determinants; for odontoid type I/III, age ≤85 years, a displaced fracture, and cervical subluxation were determinants; for non-odontoid fractures, cervical subluxation and cervical ligament sprain were the strongest determinants for surgery, by hierarchy. Conclusions: This is the largest published study of C2 fractures and current surgical management in the USA. Odontoid fractures, regardless of type, had age and fracture displacement as the strongest determinants for surgical management, whereas associated injuries were determinants of surgery for non-odontoid fractures. Level of evidence: III.

Long COVID: Is there a kidney link?

Metabolic causes such as altered bioenergetics and amino acid metabolism may play a major role in Long COVID. Renal-metabolic regulation is an integral part of these pathways but has not been systematically or routinely investigated in Long COVID. Here we discuss the biochemistry of renal tubular injury as it may contribute to Long COVID symptoms. We propose three potential mechanisms that could be involved in Long COVID namely creatine phosphate metabolism, un-reclaimed glomerular filtrate and COVID specific proximal tubule cells (PTC) injury-a tryptophan paradigm. This approach is intended to allow for improved diagnostics and therapy for the long-haul sufferers.

Border-fence falls versus domestic falls at a South Texas trauma center.

Objectives: Falling from height may lead to significant injuries and time hospitalized; however, there are few studies comparing the specific mechanism of fall. The purpose of this study was to compare injuries from falls after attempting to cross the USA-Mexico border fence (intentional) with injuries from domestic falls (unintentional) of comparable height. Methods: This retrospective cohort study included all patients admitted after a fall from a height of 15-30 ft to a level II trauma center between April 2014 and November 2019. Patient characteristics were compared by falls from the border fence with those who fell domestically. Fisher's exact test, χ2 test and Wilcoxon Mann-Whitney U test were used as appropriate. A significance level of α<0.05 was used. Results: Of the 124 patients included, 64 (52%) were falls from the border fence while 60 (48%) were domestic falls. Patients sustaining injuries from border falls were on average younger than patients who had domestic falls (32.6 (10) vs 40.0 (16), p=0.002), more likely males (58% vs 41%, p<0.001), fell from a significantly higher distance (20 (20-25) vs 16.5 (15-25), p<0.001), and had a significantly lower median injury severity score (ISS) (5 (4-10) vs 9 (5-16.5), p=0.001). Additionally, compared with domestic falls, border falls had fewer injuries to the head (3% vs 25%, p=0.004) and chest (5% vs 27%, p=0.007), yet more extremity injuries (73% vs 42%, p=0.003), and less had an intensive care unit (ICU) stay (30% vs 63%, p=0.002). No significant differences in mortality were found. Conclusion: Patients sustaining injuries from border crossing falls were slightly younger, and although fell from higher, had a lower ISS, more extremity injuries, and fewer were admitted to the ICU compared with patients sustaining falls domestically. There was no difference in mortality between groups. Level of evidence: Level III, retrospective study.

Hypoxia Dysregulates the Transcription of Myoendothelial Junction Proteins Involved with Nitric Oxide Production in Brain Endothelial Cells.

Myoendothelial junctions (MEJs) are structures that allow chemical signals to be transmitted between endothelial cells (ECs) and vascular smooth muscle cells, which control vascular tone. MEJs contain hemoglobin alpha (Hbα) and endothelial nitric oxide synthase (eNOS) complexes that appear to control the production and scavenging of nitric oxide (NO) along with the activity of cytochrome b5 reductase 3 (CYB5R3). The aim of this study was to examine how hypoxia affected the regulation of proteins involved in the production of NO in brain ECs. In brief, human brain microvascular endothelial cells (HBMEC) were exposed to cobalt chloride (CoCl2), a hypoxia mimetic, and a transcriptional analysis was performed using primers for eNOS, CYB5R3, and Hbα2 with ΔΔCt relative gene expression normalized to GAPDH. NO production was also measured after treatment using 4,5-diaminofluorescein diacetate (DAF-DA), a fluorescent NO indicator. When HBMEC were exposed to CoCl2 for 48 h, eNOS and CYB5R3 messenger RNA significantly decreased (up to -17.8 ± 4.30-fold and -10.4 ± 2.8, respectively) while Hbα2 increased to detectable levels. Furthermore, CoCl2 treatment caused a redistribution of peripheral membrane-generated NO production to a perinuclear region. To the best of our knowledge, this is the first time this axis has been studied in brain ECs and these findings imply that hypoxia may cause dysregulation of proteins that regulate NO production in brain MEJs.

Correlation between intracranial pressure monitoring for severe traumatic brain injury with hospital length of stay and discharge disposition: a retrospective observational cohort study.

OBJECTIVES: Intracranial pressure (ICP) monitoring is recommended for severe traumatic brain injuries (TBI) but some data suggests it may not improve outcomes. The objective was to investigate the effect of ICP monitoring among TBI. METHODS: This retrospective observational cohort study (1/1/2015-6/1/2020) included severe TBI patients. Outcomes [discharge destination, length of stay (LOS)] were compared by ICP monitoring and were stratified by GCS (3 vs. 4-8), α < 0.05. RESULTS: Of the123 patients who met inclusion criteria, 47% received ICP monitoring. There were baseline differences in the two groups characteristics, ICP monitored patients were younger (p = 0.02), had a subarachnoid hemorrhage less often (p = 0.04), and a subdural hematoma more often (p = 0.04) than those without ICP monitors. ICP monitored patients had a significantly longer median LOS (12 vs. 3, p < 0.01) than patients without monitoring. There was a trend towards more ICP monitored patients discharged home (40% vs. 23%, p = 0.06). Among patients with GCS = 3, ICP monitored patients had a longer LOS (p < 0.01) with no significant differences in discharge destinations. For those with a GCS of 4-8, ICP monitoring was associated with a longer LOS (p = 0.01), but fewer were discharged to a skilled nursing facility or long-term care (p = 0.01). CONCLUSIONS: For TBI patients, ICP monitoring was associated with an increased LOS, with no significant differences in discharge destinations when compared to those without ICP monitoring. However, among only those with a GCS of 4-8, ICP monitoring was associated with a decreased proportion of patients discharged to a skilled nursing facility or long-term acute care .

Profile of neurological manifestations in patients with COVID-19: Review of the literature published during the first six months of the pandemic

Introduction: Several studies describing different neurological manifestations in patients with COVID-19 were published during the first six months of the pandemic. Objective: To collect and synthesize the scientific evidence published within the first six months after COVID-19 was declared a pandemic on neurological manifestations in patients infected with SARS-CoV-2, as well as their prevalence and variations in specific populations. Materials and methods: A literature search was conducted in PubMed/MEDLINE using the following search strategy: types of study: any study describing neurological manifestations in COVID-19 patients; publication period: March 11-August 31, 2020; publication language: English; search terms and search equation: (("COVID-19") AND "Neurologic Manifestations"). Results: The initial search yielded 388 records, of which 79 met the eligibility criteria and were included for full analysis. Most studies were case reports (50.63% individual case reports and 18.99% case series), while only 30.38% were analytical studies, with cross-sectional studies being the most common (n=25). The most frequently described neurological manifestation was smell and/or taste disorder (43.04%), followed by peripheral neuropathy (20.25%), seizures (8.86%), encephalitis (7.59%), and delirium (5.06%). Other manifestations reported to a lesser extent included headache, myositis, stroke, and transverse myelitis. Conclusion: Most neurological manifestations reported have a favorable progress, occur in young patients without any comorbidity, and are unrelated to the severity of the disease. Other manifestations such as delirium and epileptic seizures occur more frequently in people with a history of dementia or epilepsy, respectively. Finally, some manifestations such as Guillain-Barré syndrome and stroke may cause several sequelae.

Introducción. Durante los primeros seis meses de la pandemia por COVID-19 se publicaron varios estudios que describen diferentes manifestaciones neurológicas en pacientes con esta enfermedad. Objetivo. Recopilar y sintetizar evidencia científica publicada en los seis meses posteriores a la declaración de la pandemia por COVID-19 sobre manifestaciones neurológicas en pacientes infectados con SARS-CoV-2, así como sus variaciones y frecuencia en poblaciones específicas. Materiales y métodos. Se realizó una búsqueda de la literatura en PubMed/Medline mediante la siguiente estrategia de búsqueda: tipos de estudio: cualquier estudio que describiera manifestaciones neurológicas en pacientes con COVID-19; periodo de publicación: marzo 11 a agosto 31, 2020; idioma de publicación: inglés; términos y ecuación de búsqueda: (("COVID-19") AND "Neurologic Manifestations"). Resultados. La búsqueda inicial arrojó 388 registros, de los cuales 79 cumplieron los criterios de elegibilidad. La mayoría de los estudios fueron reportes de caso (50.63% fueron reportes individuales de caso y 18.99%, series de casos), mientras que solo 30.38% fueron estudios analíticos, siendo los estudios transversales los más frecuentes (n=20). La manifestación neurológica descrita más frecuentemente fue la alteración de olfato y/o gusto (43.04%), seguida de neuropatía periférica (20.25%), convulsiones (8.86%), encefalitis (7.59%) y delirium (5.06%). Otras manifestaciones reportadas en menor proporción fueron cefalea, miositis, accidente cerebrovascular (ACV) y mielitis transversa. Conclusión. La mayoría de las manifestaciones neurológicas de la COVID-19 reportadas tienen una evolución favorable, ocurren en pacientes jóvenes sin comorbilidades y no tienen relación con la severidad de la enfermedad. Otras manifestaciones, como delirium y crisis epilépticas, se presentan con mayor frecuencia en población con antecedente de demencia o epilepsia, respectivamente. Por último, algunas manifestaciones como el síndrome de Guillain-Barré y los ACV pueden causar secuelas.

Case report: Tree branch penetrating injury into zone III of the neck.

INTRODUCTION: Penetrating trauma to the neck can result in severe morbidity and mortality. Location of the injury dictates the appropriate clinical management. Challenging traumatic injuries require resourceful treatment options. CASE PRESENTATION: A complex traumatic case of a foreign body penetrating the neck, the parotid gland, disrupting the internal jugular vein, with the tip resting at the anterior aspect of the C1 ring is reported. In this case, the authors seek to describe the clinical management of a vascular injury that resulted from penetrating zone III of the neck. DISCUSSION: Due to the complex and dense presence of various structures in the neck, injuries can be difficult to manage. Thus, an algorithm identifies management strategies that are based on the location of the injury, signs of vascular injury, identified injured structures and the hemodynamic stability of the patient. Balloon tamponade has been described in other organs of the body and might be a therapeutic option in patients were venous injuries are difficult to access. CONCLUSION: Penetrating neck injuries continue to result in significant morbidity and mortality. However, with appropriate and efficient evaluation and management, better outcomes are expected as demonstrated in this case.

Evaluation of therapy in traumatic elderly falls to return autonomy and functional status.

Background: Traumatic falls among the elderly (≥ 65 years old) are the leading cause of injury, morbidity and mortality are increasing with rising medical costs. Methods: This is a retrospective medical record review of elderly mechanical fall patients (288 patients) admitted to an American College of Surgeons level II trauma center from January 2016 to January 2021. Demographics and comorbidities were determined, and physical/occupational therapy used to predict subsequent fall readmissions. Results: Out of 288 patients, 243 received therapy with 45 readmissions for subsequent falls. Age (P = .016), body mass index (P = .035), previous falls (P = .003), walker/cane use (P = .039), and dementia (P = .038) were predictive of readmission. Therapy was shown to benefit patients, but deferred therapy sessions were shown to be associated with prolonged hospitalization. Conclusion: Directed therapy may improve functionality and return autonomy to elderly mechanical fall patients admitted to trauma services.

Tokyo Guidelines (TG18) for Acute Cholangitis Provide Improved Specificity and Accuracy Compared to Fellow Assessment.

Background Acute cholangitis results in significant mortality unless treated promptly. The diagnostic grading criteria of the 2018 Tokyo Guidelines (TG18) are used worldwide as the standard for acute cholangitis (AC) management but validation in clinical practice is required. Aim Use of the Tokyo 2018 (TG18) guidelines in improving the diagnostic accuracy and early detection of AC compared to fellow clinical assessment. Methods A retrospective review of patient records from 1/2010-9/2019 seen at Augusta University - Medical College of Georgia with the International Classification of Diseases, Ninth Revision (ICD-9) code "cholangitis" and/or ICD-10 codes "acute cholangitis, other cholangitis, and calculus of bile duct with cholangitis" was performed. Inclusion criteria were gastroenterology inpatient consult fellow evaluation and clinical diagnosis of AC. A definitive diagnosis of AC was determined following endoscopic retrograde cholangiopancreatography (ERCP). TG18 scoring for AC was then performed, categorized as either diagnostic/non-diagnostic, and compared to fellow clinical assessments following definitive diagnosis post-ERCP. Data were analyzed with chi-square testing. Results Two hundred six patients were identified using ICD codes. Ninety-one met inclusion criteria and were analyzed. The mean patient age of the overall group was 67 years old (standard deviation of 13.3 years) with males comprising 69% and non-Hispanic white 56% of the study group. TG18 criteria assessment had a sensitivity of 86% and specificity of 63% for patients with AC post ERCP (p <0.05). TG18 accuracy was 81%. In comparison, fellow clinical suspicion had a sensitivity of 90.3% and specificity of 0% (NS). Fellow accuracy was 71%. No difference in fellows' diagnosis of suspected AC was noted based on the training year. Conclusion Application of the TG18 criteria for AC reduces the false positive rate and improves diagnostic accuracy, thus decreasing costs along with avoiding unnecessary ERCPs with associated complications.

Suicide versus homicide firearm injury patterns on trauma systems in a study of the National Trauma Data Bank (NTDB).

Firearm related mortality in the USA surpassed all other developed countries. This study hypothesizes that injury patterns, weapon type, and mortality differ between suicide groups as opposed to homicide. The American College of Surgeons National Trauma Database was queried from January 2017 to December 2019. All firearm related injuries were included, and weapon type was abstracted. Differences between homicide and suicide groups by sex, age, race, and injury severity were compared using a Mann-Whitney test for numerical data and Fisher's exact test for categorical data. The association between weapon type and mortality relative to suicide as opposed to homicide was assessed in Fisher's exact tests. Significance was defined as p < 0.05. There were 100,031 homicide and 11,714 suicide subjects that met inclusion criteria. Homicides were mostly assault victims (97.6%), male (88%), African-American (62%), had less severe injury (mean (ISS) 12.07) and a median age of 20 years old (IQR: 14, 30, p < 0.01). Suicides were mostly male (83%), white (79%), had more severe injury (mean ISS 20.73), and a median age of 36 years old (IQR: 19, 54, p < 0.01). Suicide group had higher odds of head/neck (OR = 13.6) or face (OR = 5.7) injuries, with lower odds of injury to chest (OR = 0.55), abdominal or pelvic contents (OR = 0.25), extremities or pelvic girdle (OR = 0.15), or superficial soft tissue (OR = 0.32). Mortality rate was higher for suicide group (44.8%; 95% confidence interval (CI) 43.9%, 45.7%) compared to the homicide group (11.5%; 95% CI 11.3%, 11.7%). Suicide had higher mortality, more severe injuries, and more head/neck/facial injuries than homicide. Majority of suicides were with handguns.

Enhancing Part-to-Part Repeatability of Force-Sensing Resistors Using a Lean Six Sigma Approach.

Polymer nanocomposites have found wide acceptance in research applications as pressure sensors under the designation of force-sensing resistors (FSRs). However, given the random dispersion of conductive nanoparticles in the polymer matrix, the sensitivity of FSRs notably differs from one specimen to another; this condition has precluded the use of FSRs in industrial applications that require large part-to-part repeatability. Six Sigma methodology provides a standard framework to reduce the process variability regarding a critical variable. The Six Sigma core is the DMAIC cycle (Define, Measure, Analyze, Improve, and Control). In this study, we have deployed the DMAIC cycle to reduce the process variability of sensor sensitivity, where sensitivity was defined by the rate of change in the output voltage in response to the applied force. It was found that sensor sensitivity could be trimmed by changing their input (driving) voltage. The whole process comprised: characterization of FSR sensitivity, followed by physical modeling that let us identify the underlying physics of FSR variability, and ultimately, a mechanism to reduce it; this process let us enhance the sensors' part-to-part repeatability from an industrial standpoint. Two mechanisms were explored to reduce the variability in FSR sensitivity. (i) It was found that the output voltage at null force can be used to discard noncompliant sensors that exhibit either too high or too low sensitivity; this observation is a novel contribution from this research. (ii) An alternative method was also proposed and validated that let us trim the sensitivity of FSRs by means of changing the input voltage. This study was carried out from 64 specimens of Interlink FSR402 sensors.