Here’s What Happens When the Coronavirus Enters the Lungs
Two new studies shed light on how SARS-CoV-2 infects the lungs.
In the first detailed atomic-level model, researchers from the U.S. Department of Energy’s Brookhaven National Laboratory have shown how a COVID protein joins forces with a protein in the lungs to do its damage.
The combination happens when the SARS-CoV-2 ‘envelope’ protein (E) takes advantage of the structure of a chain of amino acids making up a human lung-cell-junction protein called PALS1. PALS1 folds to form three structural domains, making it possible for the much smaller chain of amino acids that makes up the E protein to fit in a hydrophobic pocket between two of those domains.
When the lung cell junctions are thus disrupted, immune cells attempt to fix the damage. They release cytokines, and this immune response triggers massive inflammation, causing the “cytokine storm” and subsequent acute respiratory distress syndrome. The study appeared in a recent issue of Nature Communications.
Investigators from the University of Technology Sydney looked at how coronavirus aerosols flow through the lower lungs, finding between 32% and 35% are deposited in the first 17 branches of the airways. That means some 65% end up reaching the deepest regions of the lungs, including the alveoli.
The researchers also found more of these particles lodge in the right lung than the left lung. Three different flow rates – 7.5, 15, and 30 liters per minute – were tested, and the model showed greater virus deposition at lower flow rates.
The authors believe their results improve the understanding of SARS-CoV-2 transmission and may also help inform the development of new aerosol delivery devices capable of reaching the deepest areas of the lung. The study was published in Physics of Fluids.
Extubation Protocol Decreases Ventilation Time for Cardiac Surgery Patients
Duke University Hospital implemented an extubation protocol implemented in a cardiac surgery ICU. As a result, the protocol effectively increased the number of patients extubated within six hours of admission to the ICU from 47.5% to 72.5%. Developed with input from members of the interdisciplinary team, the protocol works around barriers to extubation in three areas Duke University Hospital processes, people, and patients.
Process barriers included a lack of clarity on which patients were eligible for early extubation. They also lacked a clear plan to initiate the weaning and extubation process, along with inadequate pain management and mis-use of sedation to lower blood pressure.
Issues involving people ranged from interdisciplinary communication to poor patient progression during shift change and an absence of cross-coverage when RTs were away from the unit transporting patients.
The primary patient barrier was metabolic acidosis, but hemodynamic instability, bleeding, respiratory acidosis, and altered mental status also came into play.
The protocol, implemented in 2017, demonstrated an improvement in extubation times at three months and was sustained at the one-year mark. The study was published in the Critical Care Nurse, June edition.
Diabetes Meds Tackle Asthma Too
Vanderbilt University Medical Center, Brigham and Women’s Hospital, Harvard Medical School, and University Hospital Zurich in Switzerland researchers found that a new class of diabetes medications. This new class, known as GLP-1 receptor agents, controls blood sugar in patients with diabetes and helps to reduce lung and airway inflammation in those with concurrent asthma.
Patients with diabetes and asthma who took the medications over six months had fewer asthma exacerbations and fewer asthma symptoms. The investigators are calling for a prospective study to confirm the results of their retrospective, observational trial, but if the findings bear out, they believe these drugs may offer a new treatment to asthma patients across the board
“For patients who have type 2 diabetes and asthma, it means that some of their medications for type 2 diabetes may actually help their asthma control,” said Katherine Cahill, MD, medical director of clinical asthma research at Vanderbilt. “For patients who have asthma but may not have type 2 diabetes, it means that there could be a new class of medications that could be used for treatment.”
The study appeared in the American Journal of Respiratory and Critical Care Medicine.
New Imaging Test Shows Lung Damage Three or More Months Post-COVID
British investigators believe a newer imaging test called hyperpolarised xenon MRI may more accurately assess lingering lung damage in people who have been hospitalized with COVID-19.
They identified persistent lung damage in patients who were three months post-discharge or longer. Routine CT scans and clinical tests did not detect the damage.
“Our follow-up scans using hyperpolarised xenon MRI have found that abnormalities not normally visible on regular scans are indeed present, and these abnormalities are preventing oxygen getting into the bloodstream as it should in all parts of the lungs,” said study author Professor Fergus Gleeson, from Oxford University Hospitals.
The study was published in Radiology.
They’re Back . . .
The relaxing of COVID-19 precautions such as mask-wearing in Texas led to a rapid increase in the number of non-COVID respiratory infections this spring, find researchers from Houston Methodist who posted their paper on a preprint server in June. The study showed –
- Cases of parainfluenza rose by 424% from March to April. These cases continued increasing 189% from April through May 25.
- Seasonal coronaviruses also increased. Usually appearing in the winter and declining in March, seasonal coronaviruses increased by 211% from March to April and continued to increase in May.
- Rhinovirus and enterovirus cases increased 85% from March to April, and RSV cases increased 166% by May 25 when compared to April.
The figures are based on data on respiratory pathogens in Houston. The authors note that the CDC’s new guidance stating that fully vaccinated people no longer need to wear masks may have also influenced the results of their study.
“For more than a year, COVID-19 was the primary cause of respiratory illness in the U.S., but now as we relax restrictions, it is important for clinicians to consider other respiratory pathogens may be causing spikes in disease outside of their usual seasonal peaks,” said study author S. Wesley Long, MD, PhD.
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