A recent study, published in the online American Journal of Respiratory and Critical Care Medicine, has found possible explanations for Covid-19 patients who present with extremely low, otherwise life-threatening levels of oxygen, but no signs of difficulty in breathing.
According to researchers, how the brain responds to the low oxygen level could be one of the factors behind the condition, known as silent hypoxemia or “happy hypoxia.”
This new understanding of the condition could prevent unnecessary intubation and ventilation in patients during the current and expected second wave of coronavirus.
“While a pulse oximeter is remarkably accurate when oxygen readings are high, it markedly exaggerates the severity of low levels of oxygen when readings are low,” said lead author of the study Martin Tobin, Professor, Loyola University Chicago Stritch School of Medicine in the US.
“Another factor is how the brain responds to low levels of oxygen. As oxygen levels drop in patients with Covid-19, the brain does not respond until oxygen falls to very low levels — at which point a patient typically becomes short of breath,” he said.
It is also possible that the coronavirus is exerting a peculiar action on how the body senses low levels of oxygen which could be linked to the lack of smell, experienced by two-thirds of COVID-19 patients, according to Tobin.
While acknowledging that further research is needed, the study concludes that “features about Covid-19 that physicians find baffling become less strange when viewed in the light of long-established principles of respiratory physiology.”
“This new information may help to avoid unnecessary endotracheal intubation and mechanical ventilation, which presents risks, when the ongoing and much anticipated second wave of COVID-19 emerges,” said Tobin.
The study included a small group of coronavirus patients with very low levels of oxygen without shortness of breath or dyspnea. The term hypoxia generally refers to insufficient oxygen supply for use by the tissues.
