Diagnosis of sepsis from a drop of blood by measurement of spontaneous neutrophil motility in a microfluidic assay.

Current methods for the diagnosis of sepsis have insufficient precision, causing regular misdiagnoses. Microbiological tests can help diagnose sepsis but are usually too slow to have an impact on timely clinical-decision making. Neutrophils have high sensitivity to infections, yet measurements of neutrophil surface markers, genomic changes, and phenotype alterations have had only a marginal effect on sepsis diagnosis. Here, we report a microfluidic assay that measures the spontaneous motility of neutrophils in the context of plasma, in one droplet of blood. We measured the performance of the assay in two independent cohorts of critically ill patients suspected of sepsis. In the first cohort, we developed a machine-learning-based scoring system (sepsis score) that segregated patients with sepsis from those without sepsis. In the second cohort, we validated the sepsis score in a double-blinded, prospective case-control study. For the 42 patients across the two cohorts, the assay identified sepsis patients with 97% sensitivity and 98% specificity. The neutrophil assay could potentially be used to accurately diagnose and monitor sepsis in larger populations of at-risk patients.

Resolvin D2 Limits Secondary Tissue Necrosis After Burn Wounds in Rats.

Secondary burn necrosis is the expansion and deepening of the original burn injury several days after injury. Limiting the extent of secondary burn necrosis may improve outcomes. In this study, we examined the ability of the lipid mediator of inflammation-resolution resolvin D2 (RvD2) and chromatin-lysing enzyme (DNase) to reduce secondary burn necrosis. Male Wistar rats were injured using a brass comb with 4 prongs heated in boiling water. This method created 2 parallel rows of 4 rectangular burned areas separated by 3 unburned interspaces. Starting at 2 hours after the burn injury, rats received either 25 ng/kg RvD2 intravenously daily for 7 days or 200 U/kg DNase every 12 hours for 3 days. We documented the necrosis around the initial wounds by digital photography. We used laser Doppler to assess the total blood flux in the burn area. We evaluated the functionality of the capillary network in the interspaces by optical coherence tomography angiography. We performed histological examination of wound skin tissue samples collected at 14 days postburn. We found that the interspace areas were preserved and had higher blood flow in the RvD2-treated group, while the burn areas expanded into the interspace areas, which were confluent by 7 days postburn, in the control-untreated group. We found a larger monocyte-to-neutrophil ratio in the RvD2-treated group compared with the DNase-treated and control groups (P < .05). Overall, RvD2 suppresses secondary necrosis and starts regeneration, highlighting the role of inflammation resolution as a potential therapeutic target in burn care.

Cervical spine MRI in patients with negative CT: A prospective, multicenter study of the Research Consortium of New England Centers for Trauma (ReCONECT).

BACKGROUND: Although cervical spine CT (CSCT) accurately detects bony injuries, it may not identify all soft tissue injuries. Although some clinicians rely exclusively on a negative CT to remove spine precautions in unevaluable patients or patients with cervicalgia, others use MRI for that purpose. The objective of this study was to determine the rates of abnormal MRI after a negative CSCT. METHODS: Blunt trauma patients who either were unevaluable or had persistent midline cervicalgia and underwent an MRI of the C-spine after a negative CSCT were enrolled prospectively in eight Level I and II New England trauma centers. Demographics, injury patterns, CT and MRI results, and any changes in cervical spine management as a result of MRI imaging were recorded. RESULTS: A total of 767 patients had MRI because of cervicalgia (43.0%), inability to evaluate (44.1%), or both (9.4%). MRI was abnormal in 23.6% of all patients, including ligamentous injury (16.6%), soft tissue swelling (4.3%), vertebral disc injury (1.4%), and dural hematomas (1.3%). Rates of abnormal neurological signs or symptoms were not different among patients with normal versus abnormal MRI. (15.2 vs. 18.8%, p = 0.25). The c-collar was removed in 88.1% of patients with normal MRI and 13.3% of patients with an abnormal MRI. No patient required halo placement, but 11 patients underwent cervical spine surgery after the MRI results. Six of the eleven had neurological signs or symptoms. CONCLUSIONS: In a select population of patients, MRI identified additional injuries in 23.6% of patients despite a normal CSCT. It is uncertain if this is a true limitation of CT technology or represents subtle injuries missed in the interpretation of the scan. The clinical significance of these abnormal MRI findings cannot be determined from this study group. LEVEL OF EVIDENCE: Therapeutic study, level IV.

Surgery Clerkship Evaluations Are Insufficient for Clinical Skills Appraisal: The Value of a Medical Student Surgical Objective Structured Clinical Examination.

OBJECTIVE: Optimal methods for medical student assessment in surgery remain elusive. Faculty- and housestaff-written evaluations constitute the chief means of student assessment in medical education. However, numerous studies show that this approach has poor specificity and a high degree of subjectivity. We hypothesized that an objective structured clinical examination (OSCE) in the surgery clerkship would provide additional data on student performance that would confirm or augment other measures of assessment. DESIGN: We retrospectively reviewed data from OSCEs, National Board of Medical Examiners shelf examinations, oral presentations, and written evaluations for 51 third-year Harvard Medical School students rotating in surgery at Massachusetts General Hospital from 2014 to 2015. We expressed correlations between numeric variables in Pearson coefficients, stratified differences between rater groups by one-way analysis of variance, and compared percentages with 2-sample t-tests. We examined commentary from both OSCE and clinical written evaluations through textual analysis and summarized these results in percentages. RESULTS: OSCE scores and clinical evaluation scores correlated poorly with each other, as well as with shelf examination scores and oral presentation grades. Textual analysis of clinical evaluation comments revealed a heavy emphasis on motivational factors and praise, whereas OSCE written comments focused on cognitive processes, patient management, and methods to improve performance. CONCLUSIONS: In this single-center study, an OSCE provided clinical skills data that were not captured elsewhere in the surgery clerkship. Textual analysis of faculty evaluations reflected an emphasis on interpersonal skills, rather than appraisal of clinical acumen. These findings suggest complementary roles of faculty evaluations and OSCEs in medical student assessment.

Low baseline (pre-injury) blood pressure predicts inpatient mortality in elderly trauma patients: A bi-institutional study.

OBJECTIVE: The relationship between baseline (i.e., pre-injury) blood pressure and trauma outcomes in elderly patients is unknown. We therefore aimed to identify the independent impact of baseline systolic blood pressure (SBP) on inpatient mortality among elderly trauma patients. METHODS: The 2004 to 2014 trauma registries of two Level I Trauma Centers were linked to electronic health records then reviewed to identify patients ≥65 years old with available baseline vital signs. Baseline SBP was defined as mean outpatient SBP within 2 years before injury. Trauma SBP was defined as first SBP reading after presentation for trauma. Baseline and Trauma SBP were classified as Low (<110 mm Hg), Normal (110-139 mm Hg), or High (≥140 mm Hg). Logistic multivariable regression models were constructed to assess the independent impact of Baseline SBP on inpatient mortality, controlling for demographics, comorbidities, injury mechanism/severity, and Trauma SBP. RESULTS: Of 37,494 patient admissions, 4,233 met inclusion criteria. Median age was 81 years; 63.6% were female. Mortality was 5.39%. In unadjusted analyses, mortality rates were 11.01%, 5.28%, and 4.52% in the Low, Normal, and High Baseline SBP groups, respectively (p = 0.001). In multivariable analyses, patients with Low Baseline SBP had significantly increased mortality risk [OR 3.19 (95% CI 1.62-6.26), p = 0.001] compared to patients with Normal Baseline SBP, in particular when they presented with Low Trauma SBP (<110 mm Hg) [OR 6.14 (2.17-17.36), p = 0.001] or Normal Trauma SBP (110-139 mm Hg) [OR 3.87 (1.43-10.45), p = 0.008]. The mortality risk associated with Low Baseline SBP was particularly elevated among patients with a pre-existing diagnosis of hypertension [OR 4.78 (1.97-11.62), p = 0.001]. CONCLUSION: Low baseline pre-injury SBP is independently associated with more than a threefold increase in inpatient mortality among elderly trauma patients and a fivefold increase in mortality risk among patients with pre-existing hypertension. Given that blood pressure control in the elderly offers a long-term survival advantage, the paradoxical finding of decreased survival after trauma warrants further investigation. LEVEL OF EVIDENCE: Prognostic/epidemiologic study, level III.

Diabetes insipidus uncovered during conservative management of complicated acute appendicitis.

Diabetes insipidus (DI) arises from impaired function of antidiuretic hormone, characterized by hypovolemia, hypernatremia, polyuria, and polydipsia. This case is a reminder of the rare but challenging obstacle that undiagnosed DI poses in fasting surgical patients, requiring prompt recognition and vigilant management of marked homeostatic imbalances.

Virtual Airway Skills Trainer (VAST) Simulator.

This paper presents a simulation of Virtual Airway Skill Trainer (VAST) tasks. The simulated tasks are a part of two main airway management techniques; Endotracheal Intubation (ETI) and Cricothyroidotomy (CCT). ETI is a simple nonsurgical airway management technique, while CCT is the extreme surgical alternative to secure the airway of a patient. We developed identification of Mallampati class, finding the optimal angle for positioning pharyngeal/mouth axes tasks for ETI and identification of anatomical landmarks and incision tasks for CCT. Both ETI and CCT simulators were used to get physicians' feedback at Society for Education in Anesthesiology and Association for Surgical Education spring meetings. In this preliminary validation study, total 38 participants for ETI and 48 for CCT performed each simulation task and completed pre and post questionnaires. In this work, we present the details of the simulation for the tasks and also the analysis of the collected data from the validation study.

A hierarchical task analysis of cricothyroidotomy procedure for a virtual airway skills trainer simulator.

BACKGROUND: Despite the critical importance of cricothyroidotomy (CCT) for patient in extremis, clinical experience with CCT is infrequent, and current training tools are inadequate. The long-term goal is to develop a virtual airway skills trainer that requires a thorough task analysis to determine the critical procedural steps, learning metrics, and parameters for assessment. METHODS: Hierarchical task analysis is performed to describe major tasks and subtasks for CCT. A rubric for performance scoring for each task was derived, and possible operative errors were identified. RESULTS: Time series analyses for 7 CCT videos were performed with 3 different observers. According to Pearson's correlation tests, 3 of the 7 major tasks had a strong correlation between their task times and performance scores. CONCLUSIONS: The task analysis forms the core of a proposed virtual CCT simulator, and highlights links between performance time and accuracy when teaching individual surgical steps of the procedure.

3D force/torque characterization of emergency cricothyroidotomy procedure using an instrumented scalpel.

Emergency Cricothyroidotomy (CCT) is a surgical procedure performed to secure a patient's airway. This high-stakes, but seldom-performed procedure is an ideal candidate for a virtual reality simulator to enhance physician training. For the first time, this study characterizes the force/torque characteristics of the cricothyroidotomy procedure, to guide development of a virtual reality CCT simulator for use in medical training. We analyze the upper force and torque thresholds experienced at the human-scalpel interface. We then group individual surgical cuts based on style of cut and cut medium and perform a regression analysis to create two models that allow us to predict the style of cut performed and the cut medium.

Needs assessment for a focused radiology curriculum in surgical residency: a multicenter study.

BACKGROUND: Patient instability and limited radiology staffing may compel surgeons to make clinical decisions based on their independent interpretations of imaging studies. Despite potential implications for patients, no research to date has assessed the need for a diagnostic radiology curriculum in general surgery residency. METHODS: We performed a cross-sectional study of surgery faculty and residents at 13 teaching hospitals across the United States. Survey responses were summarized using frequency and percentage, and analyzed by chi-square, Mantel-Haenszel chi-square, and McNemar tests. RESULTS: Surveys were distributed to 465 faculty and 520 residents, with response rates of 26% and 30%, respectively. Most respondents reported making decisions based on their independent imaging interpretation at least sometimes, with higher frequency in acute scenarios. The majority voiced a need for a dedicated radiology curriculum, with teaching in chest x-rays, abdominal x-rays, abdominal computed tomography, chest computed tomography, and focused assessment with sonography in trauma examinations. CONCLUSIONS: Surgeons and surgical residents enact treatment plans based on their independent interpretation of imaging studies, especially during acute patient scenarios. Further curricular development efforts are warranted to ensure trainee accuracy in radiologic interpretation.

Gene Expression of Proresolving Lipid Mediator Pathways Is Associated With Clinical Outcomes in Trauma Patients.

OBJECTIVES: Specialized proresolving lipid mediators have emerged as powerful modulators of inflammation and activators of resolution. Animal models show significant benefits of specialized proresolving lipid mediators on survival and wound healing after major burn trauma. To date, no studies have investigated specialized proresolving lipid mediators and their relation to other lipid mediator pathways in humans after trauma. Here we determine if patients with poor outcomes after trauma have dysregulated lipid mediator pathways. DESIGN: We studied blood leukocyte expression of 18 genes critical to the synthesis, signaling, and metabolism of specialized proresolving lipid mediators and proinflammatory lipid mediators, and we correlated these expression patterns with clinical outcomes in trauma patients from the Inflammation and the Host Response to Injury study. SETTING: Seven U.S. medical trauma centers. SUBJECTS: Ninety-six patients enrolled in the Inflammation and Host Response to Injury study, after blunt trauma and unambiguously classified as having uncomplicated or complicated recoveries. Twenty-eight healthy volunteers were enrolled as controls. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Within each patient, the 18 genes of interest were used to calculate scores for distinct families of lipid mediators, including resolvins, lipoxins, prostaglandins, and leukotrienes, as well as leukotriene to resolvin score ratios. Scores were built using a simple weighting scheme, taking into consideration both dependent and independent activities of enzymes and receptors responsible for lipid mediator biosynthesis and function. Individually, ALOX12, PTGS2, PTGES, PTGDS, ALOX5AP, LTA4H, FPR2, PTGER2, LTB4R, HPGD, PTGR1, and CYP4F3 were expressed differentially over 28 days posttrauma between patients with uncomplicated and complicated recoveries (p < 0.05). When all genes were combined into scores, patients with uncomplicated recoveries had differential and higher resolvin scores (p < 0.001) and lower leukotriene scores (p < 0.001). A final combined ratio was calculated for each patient, and posttrauma leukotriene score to resolvin score ratios were significantly lower in patients with uncomplicated clinical courses (p < 0.001). CONCLUSIONS: proresolving lipid mediator lipidomics and/or protein expression, and identifying associated therapeutic targets, may influence the clinical management of trauma patients.

Stem cells and burns: review and therapeutic implications.

Despite significant advances in burn resuscitation and wound care over the past 30 years, morbidity and mortality from thermal injury remain high. Limited donor skin in severely burned patients hinders effective wound excision and closure, leading to infectious complications and prolonged hospitalizations. Even with large-volume fluid resuscitation, the systemic inflammatory response syndrome compromises end-organ perfusion in burn patients, with resultant multiorgan failure. Stem cells, which enhance wound healing and counteract systemic inflammation, now offer potential therapies for these challenges. Through a review of the literature, this article seeks to illustrate applications of stem cell therapy to burn care and to highlight promising areas of research.

Burn injury reduces neutrophil directional migration speed in microfluidic devices.

Thermal injury triggers a fulminant inflammatory cascade that heralds shock, end-organ failure, and ultimately sepsis and death. Emerging evidence points to a critical role for the innate immune system, and several studies had documented concurrent impairment in neutrophil chemotaxis with these post-burn inflammatory changes. While a few studies suggest that a link between neutrophil motility and patient mortality might exist, so far, cumbersome assays have prohibited exploration of the prognostic and diagnostic significance of chemotaxis after burn injury. To address this need, we developed a microfluidic device that is simple to operate and allows for precise and robust measurements of chemotaxis speed and persistence characteristics at single-cell resolution. Using this assay, we established a reference set of migration speed values for neutrophils from healthy subjects. Comparisons with samples from burn patients revealed impaired directional migration speed starting as early as 24 hours after burn injury, reaching a minimum at 72-120 hours, correlated to the size of the burn injury and potentially serving as an early indicator for concurrent infections. Further characterization of neutrophil chemotaxis using this new assay may have important diagnostic implications not only for burn patients but also for patients afflicted by other diseases that compromise neutrophil functions.

Cathelicidin family of antimicrobial peptides: proteolytic processing and protease resistance.

Cathelicidins are a gene family of antimicrobial peptides produced as inactive precursors. Signal peptidase removes the N-terminal signal sequence, while peptidylglycine alpha-amidating monooxygenase often amidates and cleaves the C-terminal region. Removal of the cathelin domain liberates the active antimicrobial peptide. For mammalian sequences, this cleavage usually occurs through the action of elastase, but other tissue-specific processing enzymes may also operate. Once released, these bioactive peptides are susceptible to proteolytic degradation. We propose that some mature cathelicidins are naturally resistant to proteases due to their unusual primary structures. Among mammalian cathelicidins, proline-rich sequences should resist attack by serine proteases because proline prevents cleavage of the scissile bond. In hagfish cathelicidins, the unusual amino acid bromotryptophan may make the active peptides less susceptible to proteolysis for steric reasons. Such protease resistance could extend the pharmacokinetic lifetimes of cathelicidins in vivo, sustaining antimicrobial activity.