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Introduction
SARS-CoV-2 (COVID-19)-associated pneumonia has generated a global pandemic, causing substantial morbidity and mortality in patients with respiratory failure.1 Ventilatory support, including mechanical ventilation, is essential to improve gas exchange and allow patient recovery. Despite its benefits, mechanical ventilation may induce further lung injury and promote an exacerbated systemic inflammatory response, a phenomenon known as ventilator-induced lung injury (VILI).2 Several strategies such as the limitation of tidal volume and driving pressure (DP) and the use of prone positioning and neuromuscular blockers have been shown to prevent VILI and have significantly improved the prognosis of patients with ARDS.3-7 Respiratory rate is a fundamental ventilatory parameter related to the energy applied to the lung parenchyma (ie, mechanical power) and constitutes a central determinant of minute ventilation and respiratory homeostasis. Even though experimental studies have shown that high frequency may aggravate lung injury,8,9 the effect of reducing frequency while maintaining CO2 and pH within safe limits remains unclear and has not been formally tested in clinical trials.
In the present study, we assessed whether a specific protocol for decreasing respiratory rate is feasible in subjects with COVID-19-associated ARDS and evaluated the impact of reducing frequency on hemodynamics, respiratory mechanics, and mechanical power.
Methods
We performed a randomized crossover trial at the Clinical Hospital of the Pontificia Universidad Católica de Chile. The study was approved by the Research Ethics Committee of the Pontificia Universidad Católica de Chile (protocol ID: 180813016).
We included subjects with COVID-19–related ARDS within the first 48 h of mechanical ventilation, PaO2/FIO2 < 200 mm Hg, and requiring deep sedation and neuromuscular blockade. Main exclusion criteria were previous chronic respiratory disease; hypercapnic respiratory failure; …
Correspondence: Guillermo Bugedo MD, Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, P.O. Box 114D, Diagonal Paraguay 362, 6° piso, Santiago, Chile. E-mail: gbugedo{at}gmail.com
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