Role of Cough Assist Device in Mechanically Ventilated Patients in Respiratory Intensive Care Unit : Assiut University Experience

Critically ill patients under invasive ventilation are at risk for sputum retention . Aspiration of respiratory secretions is a frequently needed procedure in intubated patients .

Cough is an important defence mechanism to clear mucus from the upper and lower airways . The presence of an endotracheal tube impairs the ability to cough. This prevents the enhancement of cough velocity . Furthermore, critically ill patients frequently have an impaired or no cough reflex due to depressed levels of consciousness, sedation, muscle weakness or muscle paralysis. Sputum retention, resulting from an inability to cough effectively, is one cause of extubation failure which in turn is associated with increased mortality.

There are a number of techniques to mobilise sputum and optimise airway clearance for invasively ventilated patients. Endotracheal suctioning is the most common intervention used to remove retained airway secretions from within the endotracheal tube, trachea and upper airways . Endotracheal suctioning though is not effective for clearing secretions from the lower airways .

New technologies and advanced methods have been developed to increase the effectiveness of mucus clearance in patients with acute respiratory failure, including mechanical insufflation-exsufflation devices. This technique has been described as an effective aid for mucus clearance in patients with chronic muscle weakness or neuromuscular disease.

Mechanical insufflation-exsufflation (MI-E) aids sputum clearance from upper and lower airways. This technique augments inspiratory and expiratory flows to improve sputum mobilisation, through the application of rapidly alternating positive and negative pressure, which approximates a normal cough .