Oxygen Therapy: Liberal Versus Conservative in Older Patients with COVID Disease

Abstract

The management of acute respiratory failure is more complicated in elderly patients. The reasons behind this difficulty are mainly related to the frailty and the comorbidities. In particular, the frailty is characterised by a decline in physiological capacity across several organ systems, with a resultant increased susceptibility to stressors. In a few words, frailty means diminished organ reserve, including that of the lung. The first step in the management of acute respiratory failure remains to treat hypoxemia with oxygen therapy. The primary rationale of oxygen (O₂) therapy is to prevent and correct arterial hypoxaemia (reduction of O₂ in the blood) and any resulting hypoxia (the decrease of the O₂ in the tissues) in patients with or at risk for impaired pulmonary gas exchange. The hypoxaemia is characterised by the partial pressure of O₂ less than 60 mmHg in blood gas analysis or a SaO₂ of <90% while breathing in room air [1]. Besides, over the last years, most acute treatment algorithms recommended the liberal use of a high fraction of inspired oxygen, even without first confirming the presence of a hypoxic insult. For example, for more than a century, supplemental oxygen has been used routinely in the treatment of patients with suspected acute myocardial infarction. The use of additional oxygen therapy in acute coronary syndromes (ACS) and cardiac emergencies has demonstrated to be controversial. In 2010, the American Heart Association (AHA) stated that oxygen should be delivered to patients with breathlessness, signs of heart failure, shock, or an arterial oxyhaemoglobin saturation <94% (Class I, LOE C) and not to all patients with ACS. Non-invasive monitoring of blood oxygen saturation can be useful to decide on the need for oxygen administration [2]. In 2015, some data questioned the consolidated clinical use of supplemental oxygen therapy. The Australian Air Versus Oxygen in Myocardial Infarction (AVOID) trial supported an adverse effect of oxygen. The trial reported larger infarct sizes in patients with ST-segment elevation myocardial infarction (STEMI) who received oxygen than in those who did not receive oxygen [3]. The history of oxygen supplementation in ACS is an example of the binary therapeutic option (liberal versus conservative use of oxygen). A Cochrane report from 2016 did not show any evidence supporting the routine use of oxygen in the treatment of patients with myocardial infarction [4]. In the same way for the treatment of stroke, the guidelines have affirmed that oxygen therapy may be harmful if used for non-hypoxemic patients with mild-moderate strokes [5]. Starting from these examples in this chapter, the authors analysed the evidence of oxygen therapy in the treatment of acute critical patients and acute respiratory distress syndrome (ARDS). The authors will investigate the use of oxygen therapy in light of the available physiopathological patterns of acute respiratory failure of COVID-19 disease.