Discussion
ventilator-induced lung injury, hypoxemic respiratory failure, hypoxemia, ARDS
ADVERSE EVENTS, RECRUITMENT, ADVERSE EFFECTS, ARDS, ACUTE RESPIRATORY DISTRESS SYNDROME, HYPOXEMIC RESPIRATORY FAILURE
The results of this sequential study on the physiological effects of awake prone positioning in patients with moderate-to-severe hypoxemic respiratory failure undergoing high-flow nasal oxygen can be summarized as follows:Awake prone positioning improves arterial oxygenation without serious periprocedural adverse events. However, the benefit on oxygenation is transient and, after supination, oxygenation may significantly worsen, likely reflecting patient’s deterioration.Awake prone positioning reduces respiratory rate but increases ΔAwake prone positioning increases EELI. This occurs due to recruitment of dorsal lung regions, enhanced expiratory pressure produced by higher resistance to expiratory flow and higher end-expiratory transpulmonary pressure.In prone position, the increase in EELI combined to a shift of the Prone positioning does not affect the magnitude of the pendelluft phenomenon.In intubated patients with moderate-to-severe ARDS, prone position improves oxygenation, limits ventilator-induced lung injury and decreases mortality [Over the past decade, the management of patients with hypoxemic respiratory failure has changed significantly. High-flow nasal oxygen has emerged as a means of avoiding endotracheal intubation and minimizing the adverse effects of sedation and invasive mechanical ventilation [The major SILI determinant is the intensity of ΔSeveral studies showed that awake prone position improves oxygenation, but few studies elucidated the effects of awake prone positioning on ΔOur study confirms that prone position can improve oxygenation without serious adverse events related to the procedure. This is attributable to the observed increase in EELI, caused by the positional change and, likely, to enhanced positive expiratory pressure produced by increased airway resistance to expiratory flow and higher transpulmonary end-expiratory pressure [In our cohort, prone positioning reduced respiratory rate but increased ΔIn our study, we neglected the amount of ΔIn our study, prone position reduced global and regional dynamic strain, which represents the most relevant determinant of ventilator-induced lung injury during controlled ventilation in patients with acute respiratory distress syndrome. This may contribute to the beneficial effects of prone position observed in spontaneously breathing subjects in clinical and observational studies [In our study, prone position did not affect the pendelluft phenomenon, which is one of the mechanisms of SILI [Our results have relevant clinical implications:Prone-induced improvement in oxygenation may help avoid endotracheal intubation, since hypoxemia is a relevant cause of treatment failure during noninvasive support [Prone position homogenizes lung inflation, reduces global and regional dynamic strain and respiratory rate, does not affect the amplitude of the pendelluft phenomenon, Our study has limitations. First, we assessed the effects of prone positioning after 2 h, while it has been shown that the most clinical benefit by prone positioning is observed in patients who remain prone for longer periods [