Artur Haddad Herdy et al. Amberson Vieira Assis
Oxygen is undoubtedly one of the main elements for the life of an aerobic organism. Animals with more complex structures, including humans, developed oxidative metabolism in the evolutionary process as the main source of energy production. Therefore, our ability to consume and use oxygen represents our main power plant and is closely associated with our vitality. Its measurement should undoubtedly be considered as another vital sign. When assessing athletes or people with severe pathologies, oxygen consumption (VO2) is an important marker of performance or survival. VO2 also defines essential therapies in critically-ill patients with CHF. In a series of 715 patients referred for heart transplantation, the event-free survival, such as death and transplantation in one year, was 87% with VO2 > 14, 77% between 10.1 and 14, and 65% when VO2 ≤ 10 mL/kg.min., On the other hand, values above 20 mL/kg.min are considered to have a better prognosis and may continue with the pharmacological therapy.
Recently, in the current coronavirus-19 pandemic (Sars-CoV-2), the value of arterial oxygen levels showed to be an important tool in the assessment of the severity of these patients. In the initial cases of lung injury, patients were relatively well, despite oxygen desaturation, which is not very responsive to oxygen therapy, in a clear gap between the severity of hypoxemia and symptoms, which has been described as “Happy hypoxemia”. The early monitoring of oxygen saturation since the home phase allowed the anticipation of the dyspnea onset, which already represents an indication of the advanced stage of pulmonary impairment and the imminent need for oxygen supplementation and/or invasive ventilation.
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