Assessing diaphragm dysfunction in ICU patients with COVID-19 pneumonia: A prospective observational cohort study

Objective: Ultrasonography has been commonly employed during the Coronavirus Disease 2019 (COVID-19) pandemic to assess lung and heart conditions; however, diaphragm ultrasonography (DU) has not been as widely acknowledged. This study aimed to assess the prevalence of diaphragm dysfunction (DD) in non-intubated critically ill patients with COVID-19 pneumonia on intensive care unit (ICU) admission and to examine the correlation between DD and various prognostic factors during their ICU stay. Methods: This prospective observational cohort study included 79 consecutive patients admitted to the intensive care unit (ICU) over an eight-month period. DU was performed within 24 h of admission by the same ultrasonographer. Diaphragm excursion was measured, and the diaphragmatic thickening fraction (DTF) was calculated. Results: A total of 79 patients were included in the study. Receiver operating characteristic (ROC) curve analysis identified a diaphragmatic thickening fraction (DTF) threshold of ≤25% for predicting ICU mortality (area under the curve [AUC] 0.87, sensitivity 85.1%, specificity 71.9%). Based on this cutoff, diaphragmatic dysfunction (DD) was present in 50.6% of patients on ICU admission and was associated with higher mortality (65.0% vs. 15.4%, p<0.001), fewer ICU-free days, and higher intubation rates. Survivors had significantly higher DTF values than non-survivors (30.7% vs. 18.8%, p<0.001). Multivariate analyses showed that DD on ICU admission was an independent predictor of mortality (HR 3.6, 95% CI 1.2–10.5, p=0.02), along with ferritin levels and the presence of septic shock. Conclusions: DD was common at ICU admission and was associated with higher intubation rates, fewer ICU-free days, and increased mortality. Early assessment of diaphragm function May help guide clinical management in non-intubated critically ill COVID-19 patients with acute respiratory failure, and a lower diaphragmatic thickening fraction May serve as a potential predictor of poor outcomes in these patients.