Ventilated Patients With COVID-19 Show Airflow Obstruction

Development and evaluation of a mechanical ventilator-sharing system

Background

During the COVID-19 pandemic surge in the hospitalization of critically ill patients and the global demand for mechanical ventilators, alternative strategies for device sharing were explored. We developed and assessed the performance of a system for shared ventilation that uses clinically available components to individualize tidal volumes under a variety of clinically relevant conditions. The feasibility of remote monitoring of ventilators was also assessed.

Methods

By using existing resources and off-the-shelf components, a ventilator-sharing system (VSS) that ventilates 2 patients simultaneously with a single device, and a ventilator monitoring system (VMS) that remotely monitors pulmonary mechanics were developed. The feasibility and effectiveness of VSS and VMS were evaluated in benchtop testing using 2 test lungs on a single ventilator, and then performance was assessed in translational swine models of normal and impaired lung function.

Results

In benchtop testing, VSS and VMS delivered the set individualized parameters with minimal % errors in test lungs under pressure- and volume-regulated ventilation modes, suggesting the highest precision and accuracy. In animal studies, the VSS and VMS successfully delivered the individualized mechanical ventilation parameters within clinically acceptable limits. Further, we found no statistically significant difference between the target and measured values.

Conclusion

The VSS adequately ventilated 2 test lungs or animals with variable lung conditions. The VMS accurately displayed mechanical ventilation settings, parameters, and alarms. Both of these systems could be rapidly assembled for scaling up to ventilate several critically ill patients in a pandemic or mass casualty disaster situations by leveraging off-the-shelf and custom 3D printed components.

Animal Models for the Study of SARS-CoV-2-Induced Respiratory Disease and Pathology

Emergence of the betacoronavirus SARS-CoV-2 has resulted in a historic pandemic, with millions of deaths worldwide. An unprecedented effort has been made by the medical, scientific, and public health communities to rapidly develop and implement vaccines and therapeutics to prevent and reduce hospitalizations and deaths. Although SARS-CoV-2 infection can lead to disease in many organ systems, the respiratory system is its main target, with pneumonia and acute respiratory distress syndrome as the hallmark features of severe disease. The large number of patients who have contracted COVID-19 infections since 2019 has permitted a detailed characterization of the clinical and pathologic features of the disease in humans. However, continued progress in the development of effective preventatives and therapies requires a deeper understanding of the pathogenesis of infection. Studies using animal models are necessary to complement in vitro findings and human clinical data. Multiple animal species have been evaluated as potential models for studying the respiratory disease caused by SARSCoV-2 infection. Knowing the similarities and differences between animal and human responses to infection is critical for effective translation of animal data into human medicine. This review provides a detailed summary of the respiratory disease and associated pathology induced by SARS-CoV-2 infection in humans and compares them with the disease that develops in 3 commonly used models: NHP, hamsters, and mice. The effective use of animals to study SARS-CoV-2-induced respiratory disease will enhance our understanding of SARS-CoV-2 pathogenesis, allow the development of novel preventatives and therapeutics, and aid in the preparation for the next emerging virus with pandemic potential.

Inspiratory Airway Resistance in Respiratory Failure Due to COVID-19

To measure inspiratory airflow resistance in patients with acute respiratory distress syndrome (ARDS) due to COVID-19.

Pulmonary Aspects of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a respiratory virus that gains entry via angiotensin-converting enzyme 2 (ACE2) within airway epithelium. Patients exhibit a spectrum of respiratory symptoms from asymptomatic to respiratory failure. Patient factors including obesity, tobacco use, and black race are all associated with increased ACE2 expression and may contribute to increased complications. Consolidation and ground-glass opacities on chest imaging are typical but not specific for coronavirus disease 2019 (COVID-19). Venous thromboembolism occurs infrequently when prophylactic anticoagulation is provided. However, capillary microthrombosis is nearly ubiquitous, suggesting that it contributes to hypoxemia. Remdesivir and glucocorticoids may benefit some hospitalized patients. Many of those afflicted remain symptomatic two weeks following diagnosis and continue to require health care. Total lung capacity, diffusion capacity, and maximal oxygen consumption may be reduced for months in some survivors. Lung transplant offers chronically critically ill patients new hope, and this option may have increasing potential for outpatients with COVID-19-associated fibrosis.