Impact of SARS-CoV-2 Pandemic on “Stroke Code” Imaging Utilization and Yield

BACKGROUND AND PURPOSE:Indirect consequences of the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) pandemic include those related to failure of patients to seek or receive timely medical attention for seemingly unrelated disease. We report our experience with stroke code imaging during the early pandemic months of 2020.MATERIALS AND METHODS:Retrospective review of stroke codes during the 2020 pandemic and both 2020 and matched 2019 prepandemic months was performed. Patient variables were age, sex, hospital location, and severity of symptoms based on the NIHSS. We reviewed the results of CT of the head, CTA, CTP, and MR imaging examinations and classified a case as imaging-positive if any of the imaging studies yielded a result that related to the clinical indication for the study. Both year-to-year and sequential comparisons were performed between pandemic and prepandemic months.RESULTS:A statistically significant decrease was observed in monthly stroke code volumes accompanied by a statistically significant increased proportion of positive imaging findings during the pandemic compared with the same months in the prior year (P < .001) and prepandemic months in the same year (P < .001). We also observed statistically significant increases in average NIHSS scores (P = .045 and P = .03) and the proportion of inpatient stroke codes (P = .003 and P = .03).CONCLUSIONS:During our pandemic period, there was a significantly decreased number of stroke codes but simultaneous increases in positivity rates, symptom severity, and inpatient codes. We postulate that this finding reflects the documented reluctance of patients to seek medical care during the pandemic, with the shift toward a greater proportion of inpatient stroke codes potentially reflecting the neurologic complications of the virus itself.

The impact of the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) coronavirus disease 2019 (COVID-19) pandemic has reverberated throughout virtually all facets of daily life, with implications beyond those associated with the viral infection itself. Within radiology, overall imaging use initially dropped sharply, largely due to suspension of elective clinical practice.¹ In addition, shifts in specific technique and subspecialty use have paralleled evolving recommendations regarding diagnosis, understanding of disease manifestations, and increasing recognition of delayed and chronic disease complications. For example, the role of chest CT during the pandemic underwent shifts from initial use for diagnosis, particularly when real-time polymerase chain reaction (RT-PCR) testing availability was limited, to later use primarily for assessment of patients with worsening or chronic respiratory failure.² At the time of this writing, at least partial recovery of imaging volumes has occurred in many centers.³In New York City, one of the early epicenters of COVID-19 in the world, this disease initially overtook all others in health care use, with concerns regarding the availability of hospital beds and supportive technology to accommodate the rapidly growing number of severely ill patients. Nevertheless, it was intuitively expected during the early stages of the pandemic that the frequency of other illnesses in the population would be unchanged by the presence of the virus. If anything, the multisystem strain of the disease seemed likely to exacerbate pre-existing morbidities, so that underlying neurologic, cardiovascular, metabolic, and other chronic conditions might worsen during viral infections, resulting in an increased incidence of acute events. In February, first reports of prothrombotic complications of SARS-CoV-2 were published, further supporting the likelihood of an increase in emergency presentation of vascular-related diseases such as pulmonary embolism, myocardial infarction, and stroke.⁴Paradoxically, however, reports in the cardiovascular literature showed a decrease in the incidence of diagnosed myocardial infarction during the initial weeks of the pandemic.⁵ At about the same time, reports in the media confirmed a growing suspicion that patients were choosing to stay home with cardiac and other acute symptoms that would have otherwise brought them to the emergency department due to fears of contracting the disease at health care facilities.⁶ Statistics compiled from the New York City Fire Department, which manages the city''s 911 emergency response system, showed a striking increase of emergency calls that resulted in “refusals of medical aid” during March (118%) and early April (235%).⁷ Furthermore, emergency departments noted early drops in census followed by progressive increases, the latter composed primarily of patients with COVID-19-related illness.⁸The first confirmed case of COVID-19 infection was diagnosed on RT-PCR testing at our 450-bed New York City hospital in early March 2020, with our peak occurring in early April (Fig 1). As both the emergency department and hospital censuses became dominated by patients positive for COVID-19, we noticed a trend toward a reduced frequency of stroke code–related imaging. This observed trend was later confirmed in a correspondence to the New England Journal of Medicine describing a concurrent 39% decrease in the use of the RApid processing of PerfusIon and Diffusion (RAPID; iSchemaView) software platform used at ours and many other US institutions to identify patients who might benefit from endovascular thrombectomy in the setting of acute stroke.⁹ Simultaneously, we began to note trends toward increased positivity rates of stroke code imaging, as well as shifts in patient demographics, including a greater proportion of stroke codes initiated in the inpatient setting. The purpose of this study was to retrospectively review our institution''s stroke codes during the early COVID-19 pandemic (March 1 to April 30, 2020) to quantify imaging use and further analyze the positive imaging findings.Open in a separate windowFIG 1.Hospital census March 13, 2020, through May 24, 2020, shows the timing of the COVID-19 surge. The turquoise line indicates total hospital census; the orange line, patients positive for COVID-19; and the yellow line, patients under investigation for COVID-19. N indicates the number of patients in each category.     

Patterns of virus-immune T-cell responsiveness. Comparison of (H-2(k) x H-2(b)) {arrow} H-2(b) Radiation Chimeras and negatively selected H-2(b) lymphocytes

Negatively selected H-2K(b)D(b) TDL can be induced to respond strongly to vaccinia virus presented in the context of both H-2K(k) and H-2D(b) when stimulated in irradiated H-2K(k)D(b) recipients. Addition of excess (H- 2K(k)D(b) x H-2K(b)D(b))F1 TDL, which are low responders to H-2D(b)-vaccinia virus, does not obviously suppress the reactivity pattern of the H-2K(b)D(b) T cells. However, lymphocytes from chimeras made by reconstituting H- 2K(b)D(b) mice with (H-2K(k)D(k) × H-2K(b)D(b))F(l) bone marrow cells make little, if any, cytotoxic T-cell response to vaccinia virus when sensitized in H-2K(k)D(b) recipients. We have thus documented one instance where the responder phenotype of T ceils from an F(l) {arrow} parent chimera is not equivalent to that associated with the H-2 type of the parental thymus. Lymphocytes from both the chimera and the H-2K(b)D(b) parent (after negative selection) are tolerant to the H-2K(k) and I-A(k) alloantigens encountered in the recipient, but the chimera T cells are also defective in their response to a neoantigen (vaccinia virus) presented in the context of H-2K(k) which the parental T cells invariably recognize. It is thus possible that at least part of the phenomenology associated with the F(l) {arrow} parent radiation chimeras reflects deletion of repertoire in the context of H-2 antigens present during thymocyte ontogeny on other than radiation-resistant thymic epithelium.     

Transjugular intrahepatic portosystemic shunt-placement increases arginine/asymmetric dimethylarginine ratio in cirrhotic patients

AIM：To analyze the change of dimethylarginine plasma levels in cirrhotic patients receiving transjugular intrahepatic portosystemic shunt（TIPS）.METHODS：To determine arginine,asymmetric dimethylarginine（ADMA）,symmetric dimethylarginine（SDMA）,and nitric oxide（NO） plasma levels,blood samples were collected from the superior cava,hepatic,and portal vein just before,directly after,and 3 mo after TIPS-placement.RESULTS：A significant increase in the arginine/ADMA ratio after TIPS placement was shown.Moreover,TIPS placement enhanced renal function and thereby decreased systemic SDMA levels.In patients with renal dysfunction before TIPS placement,both the arginine/ADMA ratio and creatinine clearance rate increased significantly,while this was not the case in patients with normal renal function before TIPS placement.Hepatic function did not change significantly after TIPS placement and no significant decline in ADMA plasma levels was measured.CONCLUSION：The increase of the arginine/ADMA ratio after TIPS placement suggests an increase in intracellular NO bioavailability.In addition,this study suggests that TIPS placement does not alter dimethylarginine dimethylaminohydrolase（DDAH） activity and confirms the major role of the liver as an ADMA clearing organ.     

The localization of a platelet GpIIb-IIIa-related protein in endothelial cell adhesion structures

Previous studies have shown that human endothelial cells (ECs) adhere to fibrinogen (fg) and fibronectin (fn) and organize their cytoskeleton on these substrata. However, the mechanism governing this chain of events is poorly known. In ECs glycoproteins immunologically and biochemically similar to the platelet membrane GpIIb-IIIa complex have been described. The functional role of this complex in ECs remains to be established. In this study we show that the antigens recognized by polyclonal antibodies raised against human platelet GpIIb-IIIa and crossreacting with the EC form have a discrete and well-organized distribution at cell adhesion structures. Indeed these antigens are located at vinculin-rich focal contacts found at the membrane insertion of microfilament bundles of the stress fiber type. They are also found at cell-to-cell contacts and, with a diffuse pattern, at the dorsal surface of ECs. GpIIb-IIIa antibodies, added to EC suspensions prior to plating, inhibit EC spreading on fg and vitronectin (vn) substrata in a concentration-dependent way. In contrast, the antibodies are very poorly active when the cells are seeded on fn-coated glass. The same antibodies, added to adherent cells, disrupt cell-to-cell contacts and cause their rounding and detachment. Overall these results indicate that EC GpIIb-IIIa complex is involved in controlling the adhesion mechanism of these cells to extracellular matrix proteins.