Donina ZA. Causes of Hypoxemia in COVID-19.
J EVOL BIOCHEM PHYS+ 2022;
58:73-80. [PMID:
35283538 PMCID:
PMC8897613 DOI:
10.1134/s0022093022010070]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 10/13/2021] [Accepted: 10/18/2021] [Indexed: 11/23/2022]
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.
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