Background <p>Although noninvasive ventilation (NIV) is regarded as a first-line treatment for patients experiencing respiratory failure brought on by an acute exacerbation of chronic obstructive pulmonary disease, its failure rate ranges from 5 to 40%. Compared to a physical examination and chest radiography, combined lung ultrasound (LU) which performed swiftly and conveniently at bedside in critically has a greater diagnosis accuracy. In patients with hypoxemic respiratory failure admitted to a respiratory intensive care unit, the HACOR score is used to predict NIV failure. The study's goal was to use the US diaphragm thickness (Tdi) to predict NIV failure in patients with AECOPD by comparing it to the HACOR score.</p> Methods <p>In our study, we recruited 60 COPD patients who were divided into group A: patients with noninvasive ventilation (NIV) failure and group B: patients with successful noninvasive ventilation (NIV). All patients were subjected to the following baseline assessment including full clinical examination and routine laboratory workup including ABG on admission. The APACHE II scores were calculated on admission, and HACOR score was used in 1, 6, 12, 24, and 48 h after starting NIV. US assessment of the diaphragm was performed on admission and before starting NIV. Patients were followed until ICU discharge or death.</p> Results <p>The cut-off value of Tdi (%) was 29% to predict noninvasive MV failure with sensitivity 91.7% and specificity 69.4%. The cut-off value of HACOR 6&#xa0;h was 15 to predict noninvasive MV failure with sensitivity 91.7% and specificity 72.2%.</p> Conclusion <p>Tdi and HACOR score are good predictors for noninvasive MV failure in patients with AECOPD.</p>