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.