The primary objective is to evaluate the mechanical power as a predictor of weaning of mechanical ventilation in COPD patients hospitalized in the respiratory intensive care unit of Assiut University Hospital The secondary objective is to compare between mechanical power and diaphragmatic excursion (DE) assessed by ultrasound as a predictor of weaning in these patients. Also, to investigate the association between MP and DE and mortality in these patients

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD), a public health problem that is characterized by persistent airflow limitation ,it develops when there is a significant exposure of irritants causing an inflammatory response in the lungs, it is a common cause of respiratory failure which require hospital admission that is associated with increased medical costs.

The World Health Organization reported that COPD was the fifth most common disease globally in 2020, with a prevalence of 7.8-19.7% in adults. Approximately, 60% of patients with COPD admitted with hypercapnic respiratory failure.

Acute exacerbations of chronic obstructive pulmonary disease (COPD) is characterized by acute worsening of respiratory symptoms associated with the development of severe airflow limitation, gas trapping, dynamic hyperinflation and intrinsic positive end-expiratory pressure (PEEPi). In the most severe cases, these exacerbations may cause acute respiratory failure, which may require mechanical ventilation.

The process of weaning from mechanical ventilation remains one of the most critical challenges in patients underwent mechanical ventilation in the intensive care unit (ICU). The multidisciplinary team must study the optimal time for weaning from the mechanical ventilator as premature weaning may lead to weaning failure and thus increase the risk of hospital acquired infections, costs of care, length of ICU stay, Morbidity and Mortality.

Current guidelines recommend several indices applied at the bedside to predict successful weaning from mechanical ventilation. A spontaneous breathing trial (SBT) is an appropriate way to prepare the patient for extubation; however, even after successful SBT, failure rates and subsequent reintubation can exceed 20% in the highest-risk patient.

Mechanical power (MP) is the energy delivered by the ventilator to the entire respiratory system per time unit and combines all factors affecting the energy load of the respiratory system, including pressure, tidal volume, flow rate and respiratory rate.

MP is primarily calculated as the product of the applied airway pressure and minute ventilation and can be used as an estimate of the workload exerted on the respiratory muscles during spontaneous breathing.

MP is a major determinant to ensure adequate gas exchange in the body and a key factor in assessing the ability of a patient to successfully wean from mechanical ventilation.

Therefore, a larger scale clinical study is needed to further verify the relationship between MP and weaning outcomes in all critically ill mechanically ventilated patients.

Inclusion Criteria:

• All COPD mechanically ventilated patients admitted to respiratory intensive care unit and eligible for weaning according to European respiratory society 2016 (5).

Exclusion Criteria:

- 1. Patients with associated lung pathology that may alter lung mechanics (Bronchiectasis, interstitial lung diseases, lung scarring) will be excluded from the study.

2. Tracheostomized patients.

COPD patients who are mechanically ventilated in Respiratory ICU in Assiut University Hospital.