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| Caption:When the painted turtle hibernates it essentially sedates its brain to survive in its low-oxygen environment. Authors of a new paper in PNAS hypothesize that the same dynamic may be occurring in severe Covid-19 patients who underwent sedation and ventilation. Photo Credit: Wayne |
Many Covid-19 patients who have been treated for weeks or months with mechanical ventilation have been slow to regain consciousness even after being taken off sedation. A new article in the Proceedings of the National Academy of Sciences offers the hypothesis that this peculiar response could be the effect of a hibernation-like state invoked by the brain to protect cells from injury when oxygen is scarce.
A very similar kind of state, characterized by the same signature change of brain rhythms, is not only observed in cardiac arrest patients treated by chilling their body temperature, a method called “hypothermia,” but also by the painted turtle, which has evolved a form of self-sedation to contend with long periods of oxygen deprivation, or “anoxia,” when it overwinters underwater.
“We propose that hypoxia combined with certain therapeutic maneuvers may initiate an as-yet-unrecognized protective down-regulated state (PDS) in humans that results in prolonged recovery of consciousness in severe Covid-19 patients following cessation of mechanical ventilation and in post-cardiac arrest patients treated with hypothermia,” wrote authors Nicholas D. Schiff and Emery N. Brown. “In severe Covid-19 patients we postulate that the specific combination of intermittent hypoxia, severe metabolic stress and GABA-mediated sedation may provide a trigger for the PDS.”


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