Extracellular RNA Sensing Mediates Inflammation and Organ Injury in a Murine Model of Polytrauma.

Severe traumatic injury leads to marked systemic inflammation and multiorgan injury. Endogenous drivers such as extracellular nucleic acid may play a role in mediating innate immune response and the downstream pathogenesis. Here, we explored the role of plasma extracellular RNA (exRNA) and its sensing mechanism in inflammation and organ injury in a murine model of polytrauma. We found that severe polytrauma-bone fracture, muscle crush injury, and bowel ischemia-induced a marked increase in plasma exRNA, systemic inflammation, and multiorgan injury in mice. Plasma RNA profiling with RNA sequencing in mice and humans revealed a dominant presence of miRNAs and marked differential expression of numerous miRNAs after severe trauma. Plasma exRNA isolated from trauma mice induced a dose-dependent cytokine production in macrophages, which was almost abolished in TLR7-deficient cells but unchanged in TLR3-deficient cells. Moreover, RNase or specific miRNA inhibitors against the selected proinflammatory miRNAs (i.e., miR-7a-5p, miR-142, let-7j, miR-802, and miR-146a-5p) abolished or attenuated trauma plasma exRNA-induced cytokine production, respectively. Bioinformatic analyses of a group of miRNAs based on cytokine readouts revealed that high uridine abundance (>40%) is a reliable predictor in miRNA mimic-induced cytokine and complement production. Finally, compared with the wild-type, TLR7-knockout mice had attenuated plasma cytokine storm and reduced lung and hepatic injury after polytrauma. These data suggest that endogenous plasma exRNA of severely injured mice and ex-miRNAs with high uridine abundance prove to be highly proinflammatory. TLR7 sensing of plasma exRNA and ex-miRNAs activates innate immune responses and plays a role in inflammation and organ injury after trauma.

Extracellular vesicles in sepsis plasma mediate neuronal inflammation in the brain through miRNAs and innate immune signaling.

BACKGROUND: Neuroinflammation reportedly plays a critical role in the pathogenesis of sepsis-associated encephalopathy (SAE). We previously reported that circulating plasma extracellular vesicles (EVs) from septic mice are proinflammatory. In the current study, we tested the role of sepsis plasma EVs in neuroinflammation. METHODS: To track EVs in cells and tissues, HEK293T cell-derived EVs were labeled with the fluorescent dye PKH26. Cecal ligation and puncture (CLP) was conducted to model polymicrobial sepsis in mice. Plasma EVs were isolated by ultracentrifugation and their role in promoting neuronal inflammation was tested following intracerebroventricular (ICV) injection. miRNA inhibitors (anti-miR-146a, -122, -34a, and -145a) were applied to determine the effects of EV cargo miRNAs in the brain. A cytokine array was performed to profile microglia-released protein mediators. TLR7- or MyD88-knockout (KO) mice were utilized to determine the underlying mechanism of EVs-mediated neuroinflammation. RESULTS: We observed the uptake of fluorescent PKH26-EVs inside the cell bodies of both microglia and neurons. Sepsis plasma EVs led to a dose-dependent cytokine release in cultured microglia, which was partially attenuated by miRNA inhibitors against the target miRNAs and in TLR7-KO cells. When administered via the ICV, sepsis plasma EVs resulted in a marked increase in the accumulation of innate immune cells, including monocyte and neutrophil and cytokine gene expression, in the brain. Although sepsis plasma EVs had no direct effect on cytokine production or neuronal injury in vitro, the conditioned media (CM) of microglia treated with sepsis plasma EVs induced neuronal cell death as evidenced by increased caspase-3 cleavage and Annexin-V staining. Cytokine arrays and bioinformatics analysis of the microglial CM revealed multiple cytokines/chemokines and other factors functionally linked to leukocyte chemotaxis and migration, TLR signaling, and neuronal death. Moreover, sepsis plasma EV-induced brain inflammation in vivo was significantly dependent on MyD88. CONCLUSIONS: Circulating plasma EVs in septic mice cause a microglial proinflammatory response in vitro and a brain innate immune response in vivo, some of which are in part mediated by TLR7 in vitro and MyD88 signaling in vivo. These findings highlight the importance of circulating EVs in brain inflammation during sepsis.

Sepsis-Induced Coagulopathy: A Comprehensive Narrative Review of Pathophysiology, Clinical Presentation, Diagnosis, and Management Strategies.

Physiological hemostasis is a balance between pro- and anticoagulant pathways, and in sepsis, this equilibrium is disturbed, resulting in systemic thrombin generation, impaired anticoagulant activity, and suppression of fibrinolysis, a condition termed sepsis-induced coagulopathy (SIC). SIC is a common complication, being present in 24% of patients with sepsis and 66% of patients with septic shock, and is often associated with poor clinical outcomes and high mortality. 1 , 2 Recent preclinical and clinical studies have generated new insights into the molecular pathogenesis of SIC. In this article, we analyze the complex pathophysiology of SIC with a focus on the role of procoagulant innate immune signaling in hemostatic activation--tissue factor production, thrombin generation, endotheliopathy, and impaired antithrombotic functions. We also review clinical presentations of SIC, the diagnostic scoring system and laboratory tests, the current standard of care, and clinical trials evaluating the efficacies of anticoagulant therapies.

Disparities in thoracic surgical oncology.

Disparities in access and outcomes of thoracic surgical oncology are long standing. This article examines the patient, population, and systems-level factors that contribute to these disparities and inequities. The need for research and policy to identify and solve these problems is apparent. As leaders in the field of thoracic oncology, surgeons will be instrumental in narrowing these gaps and moving the discipline forward.

Meeting Report: First Cardiovascular Outcomes Research in Perioperative Medicine Conference.

The first Cardiovascular Outcomes Research in Perioperative Medicine (COR-PM) conference took place on May 13, 2022, in Palm Springs, CA, and online. Here, we: (1) summarize the background, objective, and aims of the COR-PM meeting; (2) describe the conduct of the meeting; and (3) outline future directions for scientific meetings aimed at fostering high-quality clinical research in the broader perioperative medicine community.

TLR7 Mediates Acute Respiratory Distress Syndrome in Sepsis by Sensing Extracellular miR-146a.

TLR7 (Toll-like receptor 7), the sensor for single-stranded RNA, contributes to systemic inflammation and mortality in murine polymicrobial sepsis. Recent studies show that extracellular miR-146a-5p serves as a TLR7 ligand and plays an important role in regulating host innate immunity. However, the role of miR-146a-5p and TLR7 signaling in pulmonary inflammation, endothelial activation, and sepsis-associated acute respiratory distress syndrome remains unclear. Here, we show that intratracheal administration of exogenous miR-146a-5p in mice evokes lung inflammation, activates endothelium, and increases endothelial permeability via TLR7-dependent mechanisms. TLR7 deficiency attenuates pulmonary barrier dysfunction and reduces lung inflammatory response in a murine sepsis model. Moreover, the impact of miR-146a-5p-TLR7 signaling on endothelial activation appears to be a secondary effect because TLR7 is undetectable in the human pulmonary artery and microvascular endothelial cells (ECs), which show no response to direct miR-146a-5p treatment in vitro. Both conditioned media of miR-146a-5p-treated macrophages (Mϕ) and septic sera of wild-type mice induce a marked EC barrier disruption in vitro, whereas Mϕ conditioned media or septic sera of TLR7-/- mice do not exhibit such effect. Cytokine array and pathway enrichment analysis of the Mϕ conditioned media and septic sera identify TNFα (tumor necrosis factor α) as the main downstream effector of miR-146a-5p-TLR7 signaling responsible for the EC barrier dysfunction, which is further supported by neutralizing anti-TNFα antibody intervention. Together, these data demonstrate that TLR7 activation elicits pulmonary inflammation and endothelial barrier disruption by sensing extracellular miR-146a-5p and contributes to sepsis-associated acute respiratory distress syndrome.

Treatment outcomes of esophageal cancer in Eastern Africa: protocol of a multi-center, prospective, observational, open cohort study.

BACKGROUND: Esophageal squamous cell carcinoma (ESCC) is a major cause of cancer morbidity and mortality in Eastern Africa. The majority of patients with ESCC in Eastern Africa present with advanced disease at the time of diagnosis. Several palliative interventions for ESCC are currently in use within the region, including chemotherapy, radiation therapy with and without chemotherapy, and esophageal stenting with self-expandable metallic stents; however, the comparative effectiveness of these interventions in a low resource setting has yet to be examined. METHODS: This prospective, observational, multi-center, open cohort study aims to describe the therapeutic landscape of ESCC in Eastern Africa and investigate the outcomes of different treatment strategies within the region. The 4.5-year study will recruit at a total of six sites in Kenya, Malawi and Tanzania (Ocean Road Cancer Institute and Muhimbili National Hospital in Dar es Salaam, Tanzania; Kilimanjaro Christian Medical Center in Moshi, Tanzania; Tenwek Hospital in Bomet, Kenya; Moi Teaching and Referral Hospital in Eldoret, Kenya; and Kamuzu Central Hospital in Lilongwe, Malawi). Treatment outcomes that will be evaluated include overall survival, quality of life (QOL) and safety. All patients (≥18 years old) who present to participating sites with a histopathologically-confirmed or presumptive clinical diagnosis of ESCC based on endoscopy or barium swallow will be recruited to participate. Key clinical and treatment-related data including standardized QOL metrics will be collected at study enrollment, 1 month following treatment, 3 months following treatment, and thereafter at 3-month intervals until death. Vital status and QOL data will be collected through mobile phone outreach. DISCUSSION: This study will be the first study to prospectively compare ESCC treatment strategies in Eastern Africa, and the first to investigate QOL benefits associated with different treatments in sub-Saharan Africa. Findings from this study will help define optimal management strategies for ESCC in Eastern Africa and other resource-limited settings and will serve as a benchmark for future research. TRIAL REGISTRATION: This study was retrospectively registered with the ClinicalTrials.gov database on December 15, 2021,  NCT05177393 .

Selection of parenchymal preserving or total pancreatectomy with/without islet cell autotransplantation surgery for patients with chronic pancreatitis.

BACKGROUND: The selection of surgery between parenchymal preserving (PPS) and total pancreatectomy (TP) with/without islet cell autotransplantation (IAT) for chronic pancreatitis (CP) patients varies based on multiple factors with a scarcity in literature addressing both at the same time. The aim of this manuscript is to present an algorithm for the surgery selection based on dominant area of disease, ductal dilatation, and glycemic control and compare outcomes. METHODS: From 2017 to 2021, CP patients offered surgery at a single institution were retrospectively evaluated. RESULTS: 51 patients underwent surgery (20 [39.2%] TPIAT, 4 [7.8%] TP, and 27 [52.9%] PPS - 9 Whipple procedures, 15 distal pancreatectomies, and 3 duct drainage procedures). No significant difference was observed in baseline characteristics or perioperative outcomes except median length of stay (8 days [IQR 6-10] vs. 13 days [IQR 9-15.5], p < 0.001), attributed to insulin requirement and education for TPIAT group. No differences in postoperative complications, such as clinically significant leak and intrabdominal fluid collection (3 [11.1%] vs 2 [10%], p = 1.0), hemorrhage (0 vs. 2 [10.0%], p = 0.2), delayed feeding (1 [3.7%] vs. 5 [25.0%], p = 0.07), or wound infection (4 [14.8%] vs. 0, p = 0.1) between PPS and TPIAT groups, respectively, were observed nor requirement of long-acting insulin at discharge (2 [15.4%] vs. 7 [43.8%], p = 0.1) for pre-operatively non-diabetic patients. No significant difference in weaning off narcotics and no mortality observed. CONCLUSION: The most appropriate selection of surgery based on the algorithm yields good and comparable outcomes.

Progressive genetic modifications of porcine cardiac xenografts extend survival to 9 months.

We report orthotopic (life-supporting) survival of genetically engineered porcine cardiac xenografts (with six gene modifications) for almost 9 months in baboon recipients. This work builds on our previously reported heterotopic cardiac xenograft (three gene modifications) survival up to 945 days with an anti-CD40 monoclonal antibody-based immunosuppression. In this current study, life-supporting xenografts containing multiple human complement regulatory, thromboregulatory, and anti-inflammatory proteins, in addition to growth hormone receptor knockout (KO) and carbohydrate antigen KOs, were transplanted in the baboons. Selective "multi-gene" xenografts demonstrate survival greater than 8 months without the requirement of adjunctive medications and without evidence of abnormal xenograft thickness or rejection. These data demonstrate that selective "multi-gene" modifications improve cardiac xenograft survival significantly and may be foundational for paving the way to bridge transplantation in humans.

Innate immune TLR7 signaling mediates platelet activation and platelet-leukocyte aggregate formation in murine bacterial sepsis.

Thrombocytopenia is a common complication in sepsis and is associated with higher mortality. Activated platelets express CD62P, which facilitates platelet-leukocyte aggregate (PLA) formation and contributes to thrombocytopenia in sepsis. We have reported that thrombocytopenia in murine sepsis is partly attributable to TLR7 signaling, but the underlying mechanism is unclear. In the current study, we tested the hypothesis that TLR7 mediates platelet activation and PLA formation during sepsis. In vitro, whole blood from WT mice treated with loxoribine, a TLR7 agonist, exhibited a dose-dependent increase in activated platelets compared to the control (PBS with 0.05% DMSO) or loxoribine-treated TLR7-/- whole blood. In a murine model of sepsis, there was a significant increase in platelet activation and PLA formation 24 hours after cecal ligation and puncture (CLP) as evidenced by double positive expression of CD41+/CD62P+ and CD45+/CD62P+, respectively. The sepsis-induced PLA formation was significantly attenuated in TLR7-/- mice. Finally, in ex-vivo experiments, plasma isolated from septic mice induced WT platelet activation, but such effect was significantly attenuated in platelets deficient of TLR7. These findings demonstrate a pivotal role of TLR7 signaling in platelet activation and PLA formation during bacterial sepsis.

Overt Disseminated Intravascular Coagulation with Severe Hypofibrinogenemia During Veno-Venous Extracorporeal Membrane Oxygenation.

Disseminated intravascular coagulation (DIC) is a life-threatening hematologic derangement characterized by dysregulated thrombin generation and excessive fibrinolysis. However, DIC is poorly characterized in the extracorporeal membrane oxygenation (ECMO) population, and the underlying mechanisms are not well understood. Several mechanisms contribute to DIC in ECMO, including consumption of coagulation factors, acquired von Willebrand's syndrome leading to thrombocytopenia, and hyperfibrinolysis. There are few case reports of DIC in adult ECMO patients. Most are in the context of venoarterial ECMO, which is typically used in the setting of cardiogenic shock and cardiac arrest. These disease states themselves are known to be associated with DIC, liver failure, impaired anticoagulant mechanisms, and increased fibrinolysis. We present an unusual case of a 74-year-old man who developed overt DIC during veno-venous (VV) ECMO. DIC resulted in clinical bleeding and severe hypofibrinogenemia requiring massive cryoprecipitate transfusion of 87 pooled units. When the patient was decannulated from ECMO, his platelet count and fibrinogen concentration improved within 24 hours, suggesting that ECMO was a proximate cause of his DIC.

Cerebrovascular reactivity measurements using simultaneous 15O-water PET and ASL MRI: Impacts of arterial transit time, labeling efficiency, and hematocrit.

Cerebrovascular reactivity (CVR) reflects the capacity of the brain to meet changing physiological demands and can predict the risk of cerebrovascular diseases. CVR can be obtained by measuring the change in cerebral blood flow (CBF) during a brain stress test where CBF is altered by a vasodilator such as acetazolamide. Although the gold standard to quantify CBF is PET imaging, the procedure is invasive and inaccessible to most patients. Arterial spin labeling (ASL) is a non-invasive and quantitative MRI method to measure CBF, and a consensus guideline has been published for the clinical application of ASL. Despite single post labeling delay (PLD) pseudo-continuous ASL (PCASL) being the recommended ASL technique for CBF quantification, it is sensitive to variations to the arterial transit time (ATT) and labeling efficiency induced by the vasodilator in CVR studies. Multi-PLD ASL controls for the changes in ATT, and velocity selective ASL is in theory insensitive to both ATT and labeling efficiency. Here we investigate CVR using simultaneous 15O-water PET and ASL MRI data from 19 healthy subjects. CVR and CBF measured by the ASL techniques were compared using PET as the reference technique. The impacts of blood T1 and labeling efficiency on ASL were assessed using individual measurements of hematocrit and flow velocity data of the carotid and vertebral arteries measured using phase-contrast MRI. We found that multi-PLD PCASL is the ASL technique most consistent with PET for CVR quantification (group mean CVR of the whole brain = 42±19% and 40±18% respectively). Single-PLD ASL underestimated the CVR of the whole brain significantly by 15±10% compared with PET (p<0.01, paired t-test). Changes in ATT pre- and post-acetazolamide was the principal factor affecting ASL-based CVR quantification. Variations in labeling efficiency and blood T1 had negligible effects.

Characterization of extracellular vesicle miRNA identified in peripheral blood of chronic pancreatitis patients.

Plasma-derived extracellular vesicles (EV) can serve as markers of cell damage/disease but can also have therapeutic utility depending on the nature of their cargo, such as miRNA. Currently, there are challenges and lack of innovations regarding early diagnosis and therapeutic options within different aspects of management of patients suffering from chronic pancreatitis (CP). Use of EV as biomarkers for pancreatic health and/or as adjuvant therapy would make a difference in management of these patients. The aim of this study was to characterize the miRNA cargo of EV purified from the plasma of CP patients and compared to those of healthy participants. EVs were isolated from plasma of 15 CP patients and 10 healthy controls. Nanoparticle tracking analysis was used to determine frequency and size, while NanoString technology was used to characterize the miRNA cargo. Relevant clinical parameters were correlated with EV miRNA cargo. ~ 30 miRNA species were identified to have significantly (p < 0.05) different expression in EV from individuals with CP compared to healthy individuals; ~ 40 miRNA were differentially expressed in EV from pre-diabetic versus non-diabetic CP patients. miR-579-3p, while exhibiting significantly lower (~ 16-fold) expression in CP compared to healthy and lower (~ 24-fold) in CP narcotic users compared to the non-users, is actually enriched (~ 32-fold) within EV in pre-diabetic CP patients compared to non-diabetic CP patients. A unique pattern was identified in female CP patients. These data support the prospect of using a plasma-derived EV cargo to assess pancreatic health and its therapeutic potential in CP patients.

Bridging the postpartum gap: best practices for training of obstetrical patient navigators.

The postpartum period represents a critical window of opportunity to improve maternal short- and long-term health, including optimizing postpartum recovery, providing effective contraception, caring for mood disorders, managing weight, supporting lactation, initiating preventive care, and promoting cardiometabolic health. However, inadequate postpartum care, especially for individuals facing social and structural barriers, is common in the United States and contributes to suboptimal health outcomes with lasting consequences. Patient navigation is a patient-centered intervention that uses trained personnel to identify financial, cultural, logistical, and educational obstacles to effective healthcare and to mitigate these barriers to facilitate comprehensive and timely access to needed health services. Given the emerging evidence suggesting that patient navigation may be a promising method to improve health among postpartum individuals, our team developed a postpartum patient navigator training guide to be used in the Navigating New Motherhood 2 and other obstetrical navigation programs. Navigating New Motherhood 2 is a randomized trial exploring whether patient navigation by a trained, lay postpartum navigator for individuals with a low income can improve health and patient-reported outcomes during and after the postpartum period. Hiring and training patient navigators without health professional degrees are integral components of initiating a navigation program. However, patient navigator training is highly variable, and no guideline regarding key elements in such a training program exists for obstetrics specifically. Thus, this paper aimed to describe the core principles, content, and rationale for each element in a comprehensive postpartum patient navigator training program. Training should be centered around the following 6 core elements: (1) principles of patient navigation; (2) knowledge of pregnancy and postpartum care; (3) health education and health promotion principles; (4) cultural sensitivity and health equity; (5) care coordination and community resources; and (6) electronic medical record systems. These core elements can serve as a basis for the development of adaptable curricula for several institutions and contexts. In addition, we offer recommendations for the implementation of a navigator training program. A curriculum with built-in flexibility to meet community and institutional needs may promote the effective and sustainable use of patient navigation in the postpartum context.

Appendicitis Mortality in a Resource-Limited Setting: Issues of Access and Failure to Rescue.

BACKGROUND: Appendicitis is one of the most common emergency surgery conditions worldwide, and the incidence is increasing in low- and middle-income countries. Disparities in access to care can lead to disproportionate morbidity and mortality in resource-limited settings; however, outcomes following an appendectomy in low- and middle-income countries remain poorly described. Therefore, we aimed to describe the characteristics and outcomes of patients with appendicitis presenting to a tertiary care center in Malawi. METHODS: We conducted a retrospective analysis of the Kamuzu Central Hospital (KCH) Acute Care Surgery database from 2013 to 2020. We included all patients ≥13 years with a postoperative diagnosis of acute appendicitis. We performed bivariate analysis by mortality, followed by a modified Poisson regression analysis to determine predictors of mortality. RESULTS: We treated 214 adults at KCH for acute appendicitis. The majority experienced prehospital delays to care, presenting at least 1 week from symptom onset (n = 99, 46.3%). Twenty (9.4%) patients had appendiceal perforation. Mortality was 5.6%. The presence of a postoperative complication the only statistically significant predictor of mortality (RR 5.1 [CI 1.13-23.03], P = 0.04) when adjusting for age, shock, transferring, and time to presentation. CONCLUSIONS: Delay to intervention due to inadequate access to care predisposes our population for worse postoperative outcomes. The increased risk of mortality associated with resultant surgical complications suggests that failure to rescue is a significant contributor to appendicitis-related deaths at KCH. Improvement in barriers to diagnosis and management of complications is necessary to reduce further preventable deaths from this disease.

The Prevalence of Benign Pathology Following Major Pulmonary Resection for Suspected Malignancy.

BACKGROUND: In the era of lung cancer screening with low-dose computed tomography, there is concern that high false-positive rates may lead to an increase in nontherapeutic lung resection. The aim of this study is to determine the current rate of major pulmonary resection for ultimately benign pathology. MATERIALS AND METHODS: A single-institution, retrospective analysis of all patients > 18 y who underwent major pulmonary resection between 2013 and 2018 for suspected malignancy and had benign final pathology was performed. RESULTS: Of 394 major pulmonary resections performed for known or presumed malignancy, 10 (2.5%) were benign. Of these 10, the mean age was 61.1 y (SD 14.6). Most were current or former smokers (60%). Ninety percent underwent a fluorodeoxyglucose positron emission tomography scan. Median nodule size was 27 mm (IQR 21-35) and most were in the right middle lobe (50%). Preoperative biopsy was performed in four (40%) but were nondiagnostic. Video-assisted thoracoscopic lobectomy (70%) was the most common surgical approach. Final pathology revealed three (30%) infectious, three (30%) inflammatory, two (20%) fibrotic, and two (20%) benign neoplastic nodules. Two (20%) patients had perioperative complications, both of which were prolonged air leaks, one (10%) patient was readmitted within 30 d, and there was no mortality. CONCLUSIONS: A small percentage of patients (2.5% in our series) may undergo major pulmonary resection for unexpectedly benign pathology. Knowledge of this rate is useful to inform shared decision-making models between surgeons and patients and evaluation of thoracic surgery program performance.

Use of Continuous Glucose Monitoring for evaluation of hypoglycemia pre- and post-operatively for patients undergoing Total Pancreatectomy with Autologous Islet Cell Transplant.

INTRODUCTION: Total pancreatectomy with autologous islet transplant (TPAIT) is indicated for patients with chronic pancreatitis to improve quality of life while reducing complications from hypoglycemia. Continuous glucose monitoring (CGM) was used to assess overall islet function and the incidence of hypoglycemia pre- and post-operatively. METHODS: Nineteen patients who underwent TPAIT at a single center from 2018 to 2020 were included. Pre-operatively, patients were defined by diabetic status. HbA1c, stimulated C-peptide, and CGM were used to characterize glycemic function. RESULTS: Pre-operatively, three patients had diabetes, and 16 patients did not have diabetes. Eight out of 16 non-diabetic patients were insulin independent (50%). Of six non-diabetic patients with > 10% hypoglycemia on pre-operative CGM, 33% were insulin-independent post-operatively (P = .3). Of non-diabetic patients with ≥ 80% time in the euglycemic range, 62% were insulin-independent post-operatively (P = .2). For patients without diabetes, the median percent time in hypoglycemic range was reduced from 8% to 1% (P = .001). Delta C-peptide had a positive correlation with islet yield (P = .03). DISCUSSION: Conventional evaluation of TPAIT patients assesses primarily beta cell function. As pancreatogenic diabetes is concerning principally for the risk of hypoglycemia, assessment of alpha cell function can improve the quality of care. CGM better captures islet function and increases the identification of hypoglycemia.

Heyde Syndrome-Pathophysiology and Perioperative Implications.

Gastrointestinal (GI) bleeding in patients with calcific aortic valve stenosis (AVS), termed Heyde syndrome, was first described by Edward C. Heyde. The strong association between valvular replacement and the eradication of clinically significant GI bleeding confirmed an underlying pathophysiologic relationship. The rheologic stress created by AVS increases proteolysis of von Willebrand factor (VWF), resulting in loss of predominantly high-molecular-weight VWF (Hmw VWF). Angiodysplastic vessels present in patients with AVS, coupled with the lack of functioning Hmw VWF, increase the risk for GI bleeds. Aortic valve replacement, both surgical and transcatheter-based, is often a definitive treatment for GI bleeding, leading to recovery of Hmw VWF multimers. Perioperative management of patients involves monitoring their coagulation profiles with relevant laboratory tests and instituting appropriate management. Management can be directed in the following two ways: by improving internal release of VWF or by administration of external therapeutics containing VWF. It is important for perioperative physicians to obtain an understanding of the pathophysiology of this disease process and closely monitor the bleeding pattern so that targeted therapies can be initiated.

A Pharmacokinetic and Pharmacodynamic Investigation of an ε-Aminocaproic Acid Regimen Designed for Cardiac Surgery With Cardiopulmonary Bypass.

OBJECTIVE: To investigate the pharmacokinetics and pharmacodynamics of an ε-aminocaproic acid (EACA) regimen designed for cardiac surgery with cardiopulmonary bypass (CPB). DESIGN: Prospective observational study requiring blood sampling to measure EACA concentrations and fibrinolysis markers (fibrinogen, D-dimer, α2-antiplasmin, and tissue plasminogen activator-plasminogen activator inhibitor [tPA-PAI-1] complex). SETTING: Single-center, tertiary medical center. PARTICIPANTS: Patients who underwent cardiac surgery with CPB between 2018 and 2019 for aortic or mitral valve replacement/repair or coronary artery bypass grafting. Previous sternotomy patients were included. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: The pharmacokinetics of EACA, during CPB, were described by a 3-compartment disposition model. EACA concentrations were greater than 130 mg/L in all patients after CPB and in most patients during CPB. The D-dimer level trended up and reached a peak median level of 1.35 mg/L of fibrinogen equivalence units (FEU) at 15 minutes after protamine administration. The median change in D-dimer (ΔD-dimer) from baseline to 15 minutes after protamine was 0.34 (-0.48 to 3.81) mg/L FEU. ΔD-dimer did not correlate with EACA concentration intraoperatively, urine output, body weight, glomerular filtration rate, cell salvage volume, and ultrafiltration volume. The median 24-hour chest tube output was 445 (180-1,011) mL. CONCLUSION: This regimen provided maximum EACA concentrations near the time of protamine administration, with a total perioperative dose of 15 g. Most patients had EACA concentrations greater than the target during CPB. ΔD-dimer did not correlate with EACA concentration. The median 24-hour chest tube output compared well to similar studies that used higher doses of EACA.

The Effect of Surgical Intervention on Pediatric Burn Injury Survival in a Resource-Poor Setting.

INTRODUCTION: Burns are one of the most common injuries sustained globally. Low- and middle-income countries (LMICs) are disproportionately affected by burn injury morbidity and mortality; African children have the highest burn mortality globally. In high-income countries, early surgical intervention has shown to improve survival. However, when applied to burn victims in LMICs, improved survival in the early excision cohort (≤5 d) was not seen. Therefore, we aimed to determine the magnitude of the effect of surgical intervention on burn injury survival. METHODS: A retrospective analysis of a prospectively collected data, utilizing the Kamuzu Central Hospital Burn Database from May 2011 to July 2019, was performed. Pediatric patients (≤12 y) were included. Patients were excluded if they underwent surgical intervention for nonacute burn care management. Bivariate analyses stratifying by type of surgical intervention was performed, comparing demographics, burn characteristics, surgical intervention, and patient mortality. Standardized estimates were adjusted using the inverse-probability of treatment weights to account for confounding. Weighted logistic regression modeling was performed to determine the odds of mortality based on if a patient underwent surgical intervention. RESULTS: During the study, 2364 patients were seen at the Kamuzu Central Hospital, 1785 (75.5%) were children ≤12 y who met inclusion criteria. In the overall cohort, 342 (19.2%) underwent operations, including split-thickness skin graft (n = 196, 57.3%), debridement (n = 116, 33.9%), escharotomy (n = 19, 5.6%), and amputation (n = 1, 0.3%). The surgery cohort was older (4.2 ± 3.1 versus 3.1 ± 2.6 y, P < 0.001) with larger percent total body surface area burns (16%, interquartile range: 10-24 versus 13%, interquartile range: 8-20, P < 0.001) than those who did not have surgery. In the propensity score-weighted logistic regression predicting survival, patients undergoing surgery after burn injury had an increased odds of survival (odds ratio: 5.24, 95% confidence interval: 2.40-11.44, P = 0.003) when compared with patients not undergoing surgery. CONCLUSIONS: In this propensity-weighted analysis, surgical intervention following burn injury increases the odds of survival by a factor of 5.24 when compared with patients not undergoing surgical intervention. Efforts to enhance burn infrastructure to deliver surgical care is imperative to attenuate burn mortality in resource-poor settings.