Clinical Characteristics and Outcomes Based on Race of Hospitalized Patients With COVID-19 in a New Orleans Cohort.

BACKGROUND: In Louisiana, deaths related to COVID-19 have disproportionately occurred in Black persons. Granular data are needed to better understand inequities and develop prevention strategies to mitigate further impact on Black communities. METHODS: We conducted a retrospective study of patients admitted to an urban safety net hospital in New Orleans, Louisiana, with reactive SARS-CoV-2 testing from March 9 to 31, 2020. Clinical characteristics of Black and other racial/ethnic group patients were compared using Wilcoxon rank-sum test and Fisher exact tests. The relationship between race and outcome was assessed using day 14 status on an ordinal scale. RESULTS: This study included 249 patients. The median age was 59, 44% were male, and 86% were age ≥65 years or had ≥1 comorbidity. Overall, 87% were Black, relative to 55% Black patients typically hospitalized at our center. Black patients had longer symptom duration at presentation (6.41 vs 5.88 days; P = .05) and were more likely to have asthma (P = .008) but less likely to have dementia (P = .002). There were no racial differences in initial respiratory status or laboratory values except for higher lactate dehydrogenase in Black patients. Patient age and initial oxygen requirement, but not race (adjusted proportional odds ratio, 0.92; 95% CI, 0.70-1.20), were associated with worse day 14 outcomes. CONCLUSIONS: Our results demonstrate minor racial differences in comorbidities or disease severity at presentation, and day 14 outcomes were not different between groups. However, Black patients were disproportionately represented in hospitalizations, suggesting that prevention efforts should include strategies to limit SARS-CoV-2 exposures and transmission in Black communities as one step toward reducing COVID-19-related racial inequities.

Validation of a Low-Cost Paper-Based Screening Test for Sickle Cell Anemia.

BACKGROUND: The high childhood mortality and life-long complications associated with sickle cell anemia (SCA) in developing countries could be significantly reduced with effective prophylaxis and education if SCA is diagnosed early in life. However, conventional laboratory methods used for diagnosing SCA remain prohibitively expensive and impractical in this setting. This study describes the clinical validation of a low-cost paper-based test for SCA that can accurately identify sickle trait carriers (HbAS) and individuals with SCA (HbSS) among adults and children over 1 year of age. METHODS AND FINDINGS: In a population of healthy volunteers and SCA patients in the United States (n = 55) the test identified individuals whose blood contained any HbS (HbAS and HbSS) with 100% sensitivity and 100% specificity for both visual evaluation and automated analysis, and detected SCA (HbSS) with 93% sensitivity and 94% specificity for visual evaluation and 100% sensitivity and 97% specificity for automated analysis. In a population of post-partum women (with a previously unknown SCA status) at a primary obstetric hospital in Cabinda, Angola (n = 226) the test identified sickle cell trait carriers with 94% sensitivity and 97% specificity using visual evaluation (none of the women had SCA). Notably, our test permits instrument- and electricity-free visual diagnostics, requires minimal training to be performed, can be completed within 30 minutes, and costs about $0.07 in test-specific consumable materials. CONCLUSIONS: Our results validate the paper-based SCA test as a useful low-cost tool for screening adults and children for sickle trait and disease and demonstrate its practicality in resource-limited clinical settings.

A Novel, Adaptable Laryngeal Mask to Facilitate a Percutaneous Dilatational Tracheostomy: Proof-of-Concept Prototype Demonstration on a Mannequin Model and Cadaver.

BACKGROUND: Most percutaneous dilatational tracheostomy (PDT) mortalities result from airway-related complications. Improved airway pressure management and gas delivery are targets for innovation. This study describes an adaptable laryngeal mask (ALM) designed to remove the bronchoscope from the endotracheal tube (ETT) and place it in a separate lumen. Airflow and device efficacy were evaluated during PDTs with an ALM on mannequins and cadavers, respectively. METHODS: Procedures were completed by a single physician using an 8.0 mm ETT and the Ciaglia Blue Rhino method on simulation mannequins (TruCorp AirSim Traci) and fresh-frozen cadavers. Mannequin simulation tested the respiratory capabilities of an ALM utilizing a BioPac spirometer and a Maquet Servo ventilator. Qualitative analysis on device efficacy was performed on 2 fresh-frozen cadavers (1 male, 1 female). RESULTS: Preliminary ventilation testing on a PDT-able mannequin using the ALM showed an increase in airflow reaching the lungs compared with a deflated ETT. During mannequin and cadaver testing, the ALM was placed over the in situ ETT effectively, thereby removing the bronchoscope from the ETT while maintaining a continuous visual of the incision site. Both mannequin and cadaveric testing using an ALM enabled a single physician to safely perform the PDT procedure with minimal assistance. CONCLUSIONS: Initial testing using an ALM during PDT on mannequins and cadavers showed an improvement in airflow and the removal of the bronchoscope from the ETT, respectively. Further studies using the ALM in a patient population compared with standard techniques would be useful.

Controlled incremental filtration: a simplified approach to design and fabrication of high-throughput microfluidic devices for selective enrichment of particles.

The number of microfluidic strategies aimed at separating particles or cells of a specific size within a continuous flow system continues to grow. The wide array of biomedical and other applications that would benefit from successful development of such technology has motivated the extensive research in this area over the past 15 years. However, despite promising advancements in microfabrication capabilities, a versatile approach that is suitable for a large range of particle sizes and high levels of enrichment, with a volumetric throughput sufficient for large-scale applications, has yet to emerge. Here we describe a straightforward method that enables the rapid design of microfluidic devices that are capable of enriching/removing particles within a complex aqueous mixture, with an unprecedented range of potential cutoff diameter (below 1 µm to above 100 µm) and an easily scalable degree of enrichment/filtration (up to 10-fold and well beyond). A simplified model of a new approach to crossflow filtration - controlled incremental filtration - was developed and validated for its ability to generate microfluidic devices that efficiently separate particles on the order of 1-10 µm, with throughputs of tens of µL min(-1), without the use of a pump. Precise control of the amount of fluid incrementally diverted at each filtration "gap" of the device allows for the gap size (~20 µm) to be much larger than the particles of interest, while the simplicity of the model allows for many thousands of these filtration points to be readily incorporated into a desired device design. This new approach should enable truly high-throughput microfluidic particle-separation devices to be generated, even by users only minimally experienced in fluid mechanics and microfabrication techniques.

The relationship between red blood cell deformability metrics and perfusion of an artificial microvascular network.

The ability of red blood cells (RBC) to undergo a wide range of deformations while traversing the microvasculature is crucial for adequate perfusion. Interpretation of RBC deformability measurements performed in vitro in the context of microvascular perfusion has been notoriously difficult. This study compares the measurements of RBC deformability performed using micropore filtration and ektacytometry with the RBC ability to perfuse an artificial microvascular network (AMVN). Human RBCs were collected from healthy consenting volunteers, leukoreduced, washed and exposed to graded concentrations (0-0.08%) of glutaraldehyde (a non-specific protein cross-linker) and diamide (a spectrin-specific protein cross-linker) to impair the deformability of RBCs. Samples comprising cells with two different levels of deformability were created by adding non-deformable RBCs (hardened by exposure to 0.08% glutaraldehyde) to the sample of normal healthy RBCs. Ektacytometry indicated a nearly linear decline in RBC deformability with increasing glutaraldehyde concentration. Micropore filtration showed a significant reduction only for concentrations of glutaraldehyde higher than 0.04%. Neither micropore filtration nor ektacytometry measurements could accurately predict the AMVN perfusion. Treatment with diamide reduced RBC deformability as indicated by ektacytometry, but had no significant effect on either micropore filtration or the AMVN perfusion. Both micropore filtration and ektacytometry showed a linear decline in effective RBC deformability with increasing fraction of non-deformable RBCs in the sample. The corresponding decline in the AMVN perfusion plateaued above 50%, reflecting the innate ability of blood flow in the microvasculature to bypass occluded capillaries. Our results suggest that in vitro measurements of RBC deformability performed using either micropore filtration or ektacytometry may not represent the ability of same RBCs to perfuse microvascular networks. Further development of biomimetic tools for measuring RBC deformability (e.g. the AMVN) could enable a more functionally relevant testing of RBC mechanical properties.

Simple paper-based test for measuring blood hemoglobin concentration in resource-limited settings.

BACKGROUND: The measurement of hemoglobin concentration ([Hb]) is performed routinely as a part of a complete blood cell count to evaluate the oxygen-carrying capacity of blood. Devices currently available to physicians and clinical laboratories for measuring [Hb] are accurate, operate on small samples, and provide results rapidly, but may be prohibitively expensive for resource-limited settings. The unavailability of accurate but inexpensive diagnostic tools often precludes proper diagnosis of anemia in low-income developing countries. Therefore, we developed a simple paper-based assay for measuring [Hb]. METHODS: A 20-µL droplet of a mixture of blood and Drabkin reagent was deposited onto patterned chromatography paper. The resulting blood stain was digitized with a portable scanner and analyzed. The mean color intensity of the blood stain was used to quantify [Hb]. We compared the performance of the paper-based Hb assay with a hematology analyzer (comparison method) using blood samples from 54 subjects. RESULTS: The values of [Hb] measured by the paper-based assay and the comparison method were highly correlated (R(2) = 0.9598); the standard deviation of the difference between the two measurements was 0.62 g/dL. The assay was accurate within 1 g/dL 90.7% of the time, overestimating [Hb] by ≥1 g/dL in 1.9% and underestimating [Hb] by ≥1 g/dL in 7.4% of the subjects. CONCLUSIONS: This study demonstrates the feasibility of the paper-based Hb assay. This simple, low-cost test should be useful for diagnosing anemia in resource-limited settings, particularly in the context of care for malaria, HIV, and sickle cell disease patients in sub-Saharan Africa.

A simple, rapid, low-cost diagnostic test for sickle cell disease.

This communication describes a very simple, rapid and inexpensive point-of-care diagnostic test for sickle cell disease (SCD) that can conclusively differentiate between blood samples from normal healthy individuals, sickle cell trait carriers and SCD patients using the characteristic blood stain patterns produced by each sample on paper.