Nasal pressure swings as the measure of inspiratory effort in spontaneously breathing patients with de novo acute respiratory failure

Background: Excessive inspiratory effort could translate into self-inflicted lung injury, thus worsening clinical outcomesof spontaneously breathing patients with acute respiratory failure (ARF). Although esophageal manometry isa reliable method to estimate the magnitude of inspiratory effort, procedural issues significantly limit its use in dailyclinical practice. The aim of this study is to describe the correlation between esophageal pressure swings (ΔPes) andnasal (ΔPnos) as a potential measure of inspiratory effort in spontaneously breathing patients with de novo ARF.Methods: From January 1, 2021, to September 1, 2021, 61 consecutive patients with ARF (83.6% related to COVID-19)admitted to the Respiratory Intensive Care Unit (RICU) of the University Hospital of Modena (Italy) and candidate toescalation of non-invasive respiratory support (NRS) were enrolled. Clinical features and tidal changes in esophagealand nasal pressure were recorded on admission and 24 h after starting NRS. Correlation between ΔPes and ΔPnosserved as primary outcome. The effect of ΔPnos measurements on respiratory rate and ΔPes was also assessed.Results: ΔPes and ΔPnos were strongly correlated at admission (R2 = 0.88, p < 0.001) and 24 h apart (R2 = 0.94,p < 0.001). The nasal plug insertion and the mouth closure required for ΔPnos measurement did not result in significantchange of respiratory rate and ΔPes. The correlation between measures at 24 h remained significant even after splittingthe study population according to the type of NRS (high-flow nasal cannulas [R2 = 0.79, p < 0.001] or non-invasiveventilation [R2 = 0.95, p < 0.001]).Conclusions: In a cohort of patients with ARF, nasal pressure swings did not alter respiratory mechanics in the shortterm and were highly correlated with esophageal pressure swings during spontaneous tidal breathing. ΔPnos mightwarrant further investigation as a measure of inspiratory effort in patients with ARF.Trial registration: NCT03 826797. Registered October 2016.