Optimising respiratory support for early COVID-19 pneumonia: a computational modelling study. (June 2022)

• Record Type: Journal Article
• Authors: Weaver, Liam; Das, Anup; Saffaran, Sina; Yehya, Nadir; Chikhani, Marc; Scott, Timothy E.; Laffey, John G.; Hardman, Jonathan G.; Camporota, Luigi; Bates, Declan G.
• Is Part Of: British journal of anaesthesia. Volume 128:Number 6(2022)
• Page Start: 1052
• Page End: 1058
• Publication Date: 2022-06
• Subjects: acute respiratory failure -- computational modelling -- COVID-19 -- mechanical ventilation -- noninvasive respiratory support -- patient self-inflicted lung injury; Anesthesiology -- Periodicals; Anesthesia -- Periodicals; 617.9605
• DOI: 10.1016/j.bja.2022.02.037
• Languages: English
• ISSNs: 0007-0912

Abstract

Abstract: Background: Optimal respiratory support in early COVID-19 pneumonia is controversial and remains unclear. Using computational modelling, we examined whether lung injury might be exacerbated in early COVID-19 by assessing the impact of conventional oxygen therapy (COT), high-flow nasal oxygen therapy (HFNOT), continuous positive airway pressure (CPAP), and noninvasive ventilation (NIV). Methods: Using an established multi-compartmental cardiopulmonary simulator, we first modelled COT at a fixed FiO2 (0.6) with elevated respiratory effort for 30 min in 120 spontaneously breathing patients, before initiating HFNOT, CPAP, or NIV. Respiratory effort was then reduced progressively over 30-min intervals. Oxygenation, respiratory effort, and lung stress/strain were quantified. Lung-protective mechanical ventilation was also simulated in the same cohort. Results: HFNOT, CPAP, and NIV improved oxygenation compared with conventional therapy, but also initially increased total lung stress and strain. Improved oxygenation with CPAP reduced respiratory effort but lung stress/strain remained elevated for CPAP >5 cm H2 O. With reduced respiratory effort, HFNOT maintained better oxygenation and reduced total lung stress, with no increase in total lung strain. Compared with 10 cm H2 O PEEP, 4 cm H2 O PEEP in NIV reduced total lung stress, but high total lung strain persisted even with less respiratory effort. Lung-protective mechanical ventilation improved oxygenation while minimising lung injury. Conclusions: The failure of noninvasive ventilatory support to reduce respiratory effort may exacerbate pulmonary injury in patients with early COVID-19 pneumonia. HFNOT reduces lung strain and achieves similar oxygenation to CPAP/NIV. Invasive mechanical ventilation may be less injurious than noninvasive support in patients with high respiratory effort.