Airway Clearance in Neuromuscular Disorders
Respiratory health is crucial for children and adults with neuromuscular disorders. These disorders progressively weaken muscles, often including the respiratory muscles. Severely weakened respiratory muscles most commonly occurs in patients with amyotrophic lateral sclerosis (ALS), spinal muscle atrophy (SMA) type 1, muscular dystrophy (MS) and other rare neuromuscular disorders.
Neuromuscular disorders can cause breathing problems in one or more of the following ways. These problems may appear at different ages and progress over time.
- Reduced lung function and hypoventilation can develop with muscle weakness problems. With hypoventilation, the amount of air going in and out of the lungs is reduced. This can lead to lower oxygen levels and higher carbon dioxide levels in the body. Hypoventilation can occur in several ways with neuromuscular disease. Weakness of the diaphragms and other breathing muscles leads to restricted lung function. If these muscles don’t work well patients with these conditions cannot take as deep a breath as usual.
- Muscle weakness and a weak cough can make it difficult to get mucus out of the lungs leading to airway mucus plugging and chest congestion. Coughing is a natural way that our body helps keep the airways clear of mucus. A strong effective cough requires the diaphragms, chest and throat muscles to work together. Mucus that stays in the lungs can block the airways and cause atelectasis (collapse of air sacs in parts of the lungs) and make it hard to get enough oxygen. It is also easier to get a lung infection when there is extra mucus for bacteria to grow in. The reduced ability to cough leads to a buildup of mucus, recurring infections and respiratory failure.
Among people with neuromuscular disorders that lead to muscle weakness, respiratory failure is the primary cause of death. Normally, the human body uses a variety of reflexes and voluntary actions to keep the airway clear, primarily through coughing. When the muscles get too weak to perform effective coughing, mucus produced by the cells lining the various parts of the respiratory system can accumulate in the airways, partially blocking it and impairing breathing. The reduced ability to cough leads to a buildup of mucus, recurring infections and potential respiratory failure.
Pulmonary Function Testing
The respiratory function of people with neuromuscular disorders can be evaluated with routine measurements. The effectiveness of coughing can be measured by evaluating the Peak Cough Flow (PCF) as described below. The strength of the respiratory muscles can be evaluated using spirometry to determine the total lung capacity, the vital capacity (VC) , the forced expiratory lung volume (FEV), and other common measurements, along with regular monitoring of blood gases. Individuals with neuromuscular disorders should have their coughing and respiratory muscles checked regularly. It is important to monitor these patients because many of these conditions are progressive and the patient’s care will almost certainly need to be regularly altered to account for their changing condition.
Airway clearance techniques
Secretion clearance techniques include suctioning, manually-assisted cough (MAC), and mechanical insufflation-exsufflation devices. Invasive suctioning has been the long time standard for removing secretions that cannot be coughed out. Suctioning is effective in removing secretions from the upper tracheo-bronchial tree. Tracheotomies and endotracheal tubes allow for quick and easy access. Another secretion clearing technique is the manually assisted cough (MAC). MAC is safe and easy to learn and to teach. It consists of coordinating either abdominal or chest thrusts with the cooperative patient’s cough effort to increase peak cough flow. Mechanical Insufflation- Exsufflation or MI-E also know as CoughAssist.
This therapy works noninvasively to removed retained secretions. A gradual hyperinflation is provided with positive pressure followed by a rapid shift to a negative pressure which simulates a cough. This therapy can be administered by mask, mouthpiece or invasively through a tracheostomy tube.
Secretion mobilization techniques are intended to mobilize the mucus in the peripheral airways so they can be removed more easily. An advantage of secretion mobilization methods is that they don’t require the patient’s cooperation and thus can be used on infants, young children, and patients who are incapable of participating in the therapy. One basic secretion mobilization technique is chest physical therapy, which consists of a secondary individual applying external mechanical maneuvers, such as chest percussion, postural drainage, and vibration, to augment mobilization and clearance of airway secretions. HFCWO therapy vests are also available that apply vibratory forces that oscillate through the chest wall into the lungs to loosen and mobilize secretions.
The frequency of application and the preferred techniques for this type of airway clearance needs to be customized to each patient and will need to be re-evaluated regularly throughout the patient’s disease course. In general, though, patients will need assistance in clearing their airways daily.
Benefits of AffloVest HFCWO
Mobile High Frequency Chest Wall Oscillation (HFCWO) airway clearance can be an effective modality for individuals with neuromuscular disorders. HFCWO airway clearance therapy is a cornerstone technique in managing respiratory disorders associated with neuromuscular diseases such as MD, ALS, MS and Quadriplegia.
If desired, a variety of airway clearance therapies may be combined during use with the AffloVest to help optimize airway clearance. With its unique design and the ability to take full, deep breaths during treatment, nebulizer treatments and postural drainage techniques can be combined with AffloVest therapy with the goal of improving lung function and helping improve a person’s quality of life.
AffloVest was designed with ease-of-use in mind for patients, families and caregivers, to deliver airway clearance therapy that can be managed at home or in the hospital. With no bulky hoses and generators as found in other therapies, the AffloVest can be utilized in any postural position (I.e. laying down, standing, sitting, inclined, reclined etc). All to help improve the quality of life for patients with MS, MD, ALS, and other neuromuscular and respiratory diseases.