A cough assist device is a medical machine designed to help individuals clear secretions from their lungs and airways when their natural coughing ability is compromised. This equipment, also known as a mechanical insufflator-exsufflator, provides non-invasive support for patients experiencing impaired respiratory function. Its primary purpose is to simulate a natural cough, thereby helping to remove mucus and improve breathing.
How Cough Assist Devices Work
A cough assist device operates by delivering controlled air pulses and pressure shifts to help mobilize and expel mucus from the lungs. The process begins with a positive pressure phase, where the machine gradually inflates the lungs, similar to taking a deep breath. This positive pressure helps to expand the lungs and deliver air behind any accumulated secretions.
Following this inhalation phase, the device rapidly switches to a negative pressure phase, creating a vacuum-like suction that quickly pulls air out of the lungs. This swift reversal of airflow mimics the forceful exhalation of a natural cough, generating a high expiratory flow rate. The pressure change helps to dislodge mucus from the bronchial walls and propel it towards the mouth, making it easier for the patient to clear.
Who Needs Cough Assistance
Cough assist devices are typically used by individuals who cannot effectively cough and clear secretions due to muscle weakness or other conditions affecting lung mechanics. Neuromuscular disorders are a primary reason for needing such assistance, as these conditions can impair the body’s natural cough reflex. Examples include muscular dystrophy, amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), myasthenia gravis, and spinal cord injuries.
These conditions compromise the cough reflex because they weaken the muscles involved in breathing and coughing, such as the diaphragm and the muscles between the ribs. Inspiratory muscle weakness can prevent the lungs from taking in enough air for a strong cough, while expiratory muscle weakness reduces the force needed to expel secretions. Additionally, some neuromuscular diseases can affect the bulbar muscles, which are involved in glottic closure, further hindering cough effectiveness. When peak cough flow falls below certain thresholds, mechanical assistance is often indicated.
Why Airway Clearance Matters
Effective airway clearance is important for maintaining lung health and preventing respiratory complications. The respiratory tract continuously produces mucus, which traps inhaled particles, including bacteria. A strong cough is the body’s natural mechanism for expelling this mucus, ensuring clear airways.
When mucus and secretions are retained in the lungs due to an ineffective cough, they can become a breeding ground for bacteria and viruses. This accumulation increases the likelihood of respiratory infections, such as pneumonia and bronchitis. Furthermore, retained secretions can lead to blocked airways, reduced gas exchange, and conditions like atelectasis, which is the collapse of lung tissue. Over time, repeated infections and mucus buildup can cause lung damage and lead to respiratory distress.
Using a Cough Assist Device
A cough assist device can be applied using a face mask, a mouthpiece, or an adapter for a tracheostomy tube. Before beginning a session, individuals should be positioned comfortably, often sitting upright with their head supported.
A typical session involves multiple cough cycles, usually between four to six consecutive cycles for adults, followed by a brief rest period of about 20 to 30 seconds. This sequence may be repeated several times, often four to six repetitions, to ensure adequate secretion removal. The specific pressure settings and cycle duration are tailored to individual needs by a healthcare provider, such as a respiratory therapist, who provides guidance on proper use. Regular use helps to keep the lungs clear.