Causes of Hypoxemia in COVID-19

Abstract

The global pandemic of a new coronavirus disease (COVID-19) has posed challenges to public health specialists around the world associated with diagnosis, intensive study of epidemiological and clinical features of the coronavirus infection, development of preventive approaches, therapeutic strategies and rehabilitation measures. However, despite the successes achieved in the study of COVID-19 pathogenesis, many aspects that aggravate the severity of the disease and cause high mortality of patients remain unclear. The main clinical manifestation of the new variant of SARS-CoV-2 virus infection is pneumonia with massive parenchymal lesions of lung tissue, diffuse alveolar damage, thrombotic manifestations, disruption of ventilation-perfusion relationships, etc. However, symptoms in patients hospitalized with COVID pneumonia show a broad diversity: the majority has minimal manifestations, others develop severe respiratory failure complicated by acute respiratory distress syndrome (ARDS) with rapidly progressing hypoxemia that leads to high mortality. Numerous clinical data publications report that some COVID pneumonia patients without subjective signs of severe respiratory failure (dyspnea, “air hunger”) have an extremely low saturation level. As a result, there arises a paradoxical condition (called “silent hypoxia” or even “happy hypoxia”) contradicting the very basics of physiology, as it essentially represents a severe life-incompatible hypoxemia which lacks respiratory discomfort. All this raises numerous questions among professionals and has already ignited a discussion in scientific publications concerned with the pathogenesis of COVID-19. Respiratory failure is a complex clinical problem, many aspects of which remain controversial. However, according to the majority of authors, one of the first objective indicators of the clinical sign of respiratory failure are hypoxemia-associated changes in external respiration. This review addresses some possible causes of hypoxemia in COVID-19.

Impact of SARS-CoV-2 on the nervous system

“…It is common for patients with COVID-19 pneumonia to develop hypoxemia. Furthermore, many authors present examples of 'silent hypoxia' (also known as 'mysterious hypoxia' or 'asymptomatic hypoxia'), which presents as hypoxia without appropriate signs of respiratory discomfort [57]. Prolonged hypoxia can lead to many neurological complications.…”

Development of an early alert model for pandemic situations in Germany

“…(iv) Some symptoms, like "Hypoxämie" (hypoxemia), "Kopfschmerzen" (headache), "Muskelschmerzen" (muscle pain), "trockener Husten" (dry cough), and "respiratorische Insuffizienz" (respiratory insufficiency) played important roles in predicting surveillance up-trends. Hypoxemia is a symptom typically observed in severe COVID-19 cases, which is a sign of respiratory insufficiency 38 . An increase of Google searches and Tweets about these symptoms could thus indicate a general up-trend of severe cases.…”

Bioinformatic assay reveal the potential mechanism of Guizhi-Shaoyao-Zhimu decoction against rheumatoid arthritis and mild-to-moderate COVID-19

“…Pro-inflammatory cytokines and chemokines produced by host body resulting from SARS-CoV-2 infection will attract more immune cells to the infected lung, further promoting inflammatory respond, leading to the formation of a pro-inflammatory feedback loop [37] . In COVID-19 patients, lung lesions and alveolar damage induced by inflammation led to insufficient ventilation and tissue hypoxia [38] . However, hypoxia induced an increase in oxidative stress-related genes such as FOS, JUN, and HIF1A, thereby promoting CXCL8 expression and exacerbating inflammation [39] , [40] , [41] .…”