Effect of Cough Assist Device in COPD Patients Admitted to Respiratory Intensive Care Unit at Assiut University Hospital

Effective cough is a protective mechanism against respiratory tract infections. COPD patients may have impaired cough and a reduction in peak cough flows(PCF) as a result of inspiratory and expiratory muscle weakness, which causes a reduction in the pressure available to drive the cough manoeuver.

Cough augmentation with mechanical Insufflation-Exsufflation (MI-E) has been described as a technique that facilitates airway secretion clearance in COPD patients, thus avoiding hospitalisations and preventing pneumonias and episodes of respiratory failure .

Cough augmentation techniques comprise lung volume recruitment, (also termed air stacking or breaths tacking), mechanically assisted cough using mechanical insufflation-exsufflation (MI-E) device. During lung volume recruitment, the person inhales a volume of gas via the ventilator, or self-inflating resuscitation bag adapted with a one-way valve to facilitate gas holding. The person retains the inhaled volume by closing the glottis, inhales another volume of gas and then again closes the glottis; this process is repeated until maximum insufflation capacity is reached MI-E devices deliver a positive (inflation) and negative pressure (rapid deflation) delivered to the person via an oronasal interface, mouthpiece, or endotracheal or tracheostomy tube. MI-E comprises a pressure -targeted lung insufflation followed by vacuum exsufflation, enabling lung emptying and increasing peak cough flow. Alternation of pressure may be manually or automatically cycled. Pressures of 40 mmHg (insufflation) to 40 mmHg (exsufflation) (54 cmH2O) are usually most effective and best tolerated by the person .

Treatments usually comprise three to five insufflation-exsuflation cycles followed by a short period of rest to avoid hyperventilation. Treatments can be repeated until no further secretions are expectorated. MIE can be performed in isolation or in combination with manually assisted cough .

Few complications associated with MI-E devices as a drop in oxygen levels, barotrauma elevated blood pressure for more than 30 minutes have been reported, most likely due to use of pressures that are much lower than physiological cough pressures and the short duration of application .