COVID-19 increases extracorporeal coagulation during hemodialysis associated with upregulation of vWF/FBLN5 signaling in patients with severe/critical symptoms

BACKGROUND

COVID-19 has been shown to increase the risk of extracorporeal coagulation during hemodialysis in patients, but the underlying mechanism remains unclear. This study aimed to investigate the effect and mechanism of COVID-19 on the risk of extracorporeal coagulation in patients with chronic kidney disease undergoing hemodialysis.

METHODS

A retrospective analysis of the extracorporeal coagulation status of 339 hemodialysis patients at our center before and after COVID-19 infection was performed, including subgroup analyses. Post-infection blood composition was analyzed by protein spectrometry and ELISA.

RESULTS

Compared to the pre-COVID-19 infection period, COVID-19-induced extracorporeal coagulation predominantly occurred in patients with severe/critical symptoms. Further proteomic analysis demonstrated that in patients with severe/critical symptoms, the coagulation cascade reaction, platelet activation, inflammation, and oxidative stress-related pathways were significantly amplified compared to those in patients with no/mild symptoms. Notably, the vWF/FBLN5 pathway, which is associated with inflammation, vascular injury, and coagulation, was significantly upregulated.

CONCLUSIONS

Patients with severe/critical COVID-19 symptoms are at a higher risk of extracorporeal coagulation during hemodialysis, which is associated with the upregulation of the vWF/FBLN5 signaling pathway. These findings highlight the importance of early anticoagulant therapy initiation in COVID-19 patients with severe/critical symptoms, particularly those undergoing hemodialysis. Additionally, vWF/FBLN5 upregulation may be a novel mechanism for virus-associated thrombosis/coagulation.

The influence of blood composition and loading frequency on the behavior of embolus analogs

In cases of acute ischemic stroke (AIS), mechanical thrombectomy (MT) can be used to directly remove lodged thromboemboli. Despite improvements in patient outcomes, one of the key factors affecting MT success is the mechanical properties of the occlusive thrombus. Therefore, the goal of this study was to investigate the viscoelastic properties of embolus analogs (EAs) and determine the influence of EA hematocrit and loading frequency. Bovine blood EAs were created over a range of physiological hematocrits (0-60%) and cyclic uniaxial compression testing was performed at three loading frequencies to mimic in vivo loading conditions, followed by stress-relaxation testing. It was found that EAs exhibited behaviors typical of hyper-viscoelastic materials and that EA hematocrit played a large role in both EA stiffness and relaxation, with both parameters decreasing as hematocrit increased from 0 to 60%. The viscoelastic behavior of the EAs was also affected by the frequency at which they were loaded, with significant increases in peak stresses between the 0.5 and 2 Hz loaded EAs. Lower hematocrit EAs had very dense fibrin networks while the higher hematocrit EAs consisted of closely packed RBCs with little fibrin present. These results suggest that fibrin contributes to EA stiffness and relaxation behaviors while RBCs play a role in decreasing the overall viscous response and strain-rate dependency. An Ogden hyperelastic model was found to best reproduce the EA loading data while a 3-term Prony series was fit to the stress relaxation data. A hyper-viscoelastic modeling framework was then implemented combining the loading and stress-relaxation fits and the results could match the full cyclic loading data for EAs of varying hematocrit and loading frequency. The results of the experimental mechanical characterization and hyper-viscoelastic curve fitting can be incorporated in future modeling efforts to optimize mechanical thrombectomy for AIS patients.

Incidence of pulmonary embolism in COVID-19 infection in the ED: ancestral, Delta, Omicron variants and vaccines

PURPOSE

This retrospective review examines the incidence of pulmonary embolism (PE) during computed tomography pulmonary angiography (CTPA) exams performed in the emergency room setting of a tertiary care center over dominant periods of the ancestral, Delta, and Omicron variants of COVID-19.

MATERIALS/METHODS

Demographic information, patient comorbidities and risk factors, vaccination status, and COVID-19 infection status were collected from patient's charts. Incidence of PE in COVID positive patients was compared between variant waves. Subgroup analysis of vaccination effect was performed.

RESULTS

CTPA was ordered in 18.3% of COVID-19 positive patients during the ancestral variant period, 18.3% during the Delta period and 17.3% during the Omicron wave. PE was seen in 15.0% of the ancestral COVID-19 variant cohort, 10.6% in the Delta COVID cohort and 9.23% of the Omicron cohort, reflecting a 41% and 60% increased risk of PE with ancestral variants compared to Delta and Omicron periods respectively. The study however was underpowered and the difference in rate of PE did not reach statistically significance (p = 0.43 and p = 0.22). Unvaccinated patients had an 2.75-fold increased risk of COVID-associated PE during the Delta and Omicron periods (p = .02) compared to vaccinated or recovered patients.

CONCLUSION

Vaccination reduces the risk of COVID-19 associated PE. Patients infected with the Delta and Omicron COVID-19 variants may have a lower incidence of pulmonary embolism, though a larger or multi-institution study is needed to prove definitively.

Information regarding acute stroke associated with COVID-19 in online news

Patients with COVID-19 may present with neurological manifestations, lack of oxygenation, or clotting disorders such as ischemic or hemorrhagic strokes. This has been observed in even young patients with mild symptoms. The aim of this study was to explore current online news coverage of acute stroke associated with COVID-19 in the four-month period from April 2020 to July 2020, a time during which the US found itself in the center of the pandemic. The relevant Google News stories were reviewed for content. The analysis indicated that 118 online news reports covered the topic to varying degrees, including data from reputable sources, references to the neurological symptoms, and to the incidence of stroke in young patients. It is important that health professionals be aware of this risk and convey to the public the possibility of stroke due to COVID-19 so as to increase the probability of early diagnosis and optimal outcomes.

In Vitro Clot Trapping Efficiency of the FDA Generic Inferior Vena Cava Filter in an Anatomical Model: An Experimental Fluid-Structure Interaction Benchmark

PURPOSE

Robust experimental data for performing validation of fluid-structure interaction (FSI) simulations of the transport of deformable solid bodies in internal flow are currently lacking. This in vitro experimental study characterizes the clot trapping efficiency of a new generic conical-type inferior vena cava (IVC) filter in a rigid anatomical model of the IVC with carefully characterized test conditions, fluid rheological properties, and clot mechanical properties.

METHODS

Various sizes of spherical and cylindrical clots made of synthetic materials (nylon and polyacrylamide gel) and bovine blood are serially injected into the anatomical IVC model under worst-case exercise flow conditions. Clot trapping efficiencies and their uncertainties are then quantified for each combination of clot shape, size, and material.

RESULTS

Experiments reveal the clot trapping efficiency increases with increasing clot diameter and length, with trapping efficiencies ranging from as low as approximately 42% for small 3.2 mm diameter spherical clots up to 100% for larger clot sizes. Because of the asymmetry of the anatomical IVC model, the data also reveal the iliac vein of clot origin influences the clot trapping efficiency, with the trapping efficiency for clots injected into the left iliac vein up to a factor of 7.5 times greater than that for clots injected into the right iliac (trapping efficiencies of approximately 10% versus 75%, respectively).

CONCLUSION

Overall, this data set provides a benchmark for validating simulations predicting IVC filter clot trapping efficiency and, more generally, low-Reynolds number FSI modeling.

Neuroendoscopic Aspiration of Blood Clots in the Cerebral Aqueduct and Third Ventricle During Posterior Fossa Surgery in the Prone Position

BACKGROUND

During surgery in the posterior fossa in the prone position, blood can sometimes fill the surgical field, due both to the less efficient venous drainage compared to the sitting position and the horizontally positioned surgical field itself. In some cases, blood clots can wedge into the cerebral aqueduct and the third ventricle, and potentially cause acute hydrocephalus during the postoperative course.

OBJECTIVE

To illustrate a technique that can be used in these cases: the use of a flexible scope introduced through the opened roof of the fourth ventricle with a freehand technique allows the navigation of the fourth ventricle, the cerebral aqueduct, and the third ventricle in order to explore the cerebrospinal fluid pathways and eventually aspirate blood clots and surgical debris.

METHODS

We report on one patient affected by an ependymoma of the fourth ventricle, for whom we used a flexible neuroendoscope to explore and clear blood clots from the cerebral aqueduct and the third ventricle after the resection of the tumor in the prone position. Blood is aspirated with a syringe using the working channel of the scope as a sucker.

RESULTS

A large blood clot that was lying on the roof of the third ventricle was aspirated, setting the ventricle completely free. Other clots were aspirated from the right foramen of Monro and from the optic recess.

CONCLUSION

We describe this novel technique, which represents a safe and efficient way to clear the surgical field at the end of posterior fossa surgery in the prone position. The unusual endoscopic visual perspective and instrument maneuvers are easily handled with proper neuroendoscopic training.