Therapeutic plasma exchange for persistent encephalopathy associated with Covid-19.

Patients infected with COVID-19 virus, show a highly variable symptomatology which can include central nervous system (CNS) dysfunction. One of the most disabling CNS manifestations is persistent severe encephalopathy seen for weeks after the resolution of the acute viral pneumonia and associated acute systemic illnesses. The precise pathophysiology of this persistent Post COVID Encephalopathy is unknown but may involve direct viral invasion of microvascular endothelium, microvascular thrombosis, toxic neuronal effects of inflammatory products, vasoactive pathology at arteriolar level or leptomeningeal inflammation.

Two ATS recommended protocols for administration of methacholine are not equal.

Background: The 1999 American Thoracic Society methacholine challenge guidelines stated that the 5-breath dosimeter method of methacholine administration is similar to the 2-minute tidal breath method. Recent data has disputed this assertion. We examined the differences in the diagnosis of asthma using these two methods.

Predictive value of sGaw, FEF(25-75), and FEV1 for development of asthma after a negative methacholine challenge test.

Background: A 20% change in forced expiratory volume in 1 second (FEV(1)) during methacholine challenge testing (MCT) is a reliable marker of asthma. When the FEV(1) decrease is < 20%, there is controversy whether other changes in flows and conductance may be useful. We conducted this study to determine whether changes in sGaw, FEF(25 - 75), and FEV(1) in a negative MCT could predict future occurrence of asthma over a 3-year period.