The respiratory (breathing) muscles are affected in many types of muscular dystrophy (MD), increasing risk of lung complications.
Good medical management requires an individualised respiratory care plan with regular monitoring and treatment changes to suit the patient’s specific needs.
Regular evaluations of lung function help the pulmonary doctor decide when to begin particular treatments.
Respiratory muscle function should be evaluated soon after diagnosis of MD so that doctors can establish a baseline status. Lung function should be assessed from then on, one to four times annually, depending on the type of MD.
Tests to evaluate lung function require the patient to put on a mouthpiece and nose clips, and breathe into a measuring device. Lung function is compared over time; a decline shows when to start ventilatory assistance.
A healthy lifestyle can prolong stable lung function and avoid the need for hospitalisations, as follows:
• Maintaining healthy weight. Excess body weight further restricts breathing.
• Avoiding temperature extremes, humidity and crowded areas to reduce exposure to respiratory tract germs.
• Encouraging deep breathing and coughing, the body’s natural mechanisms for clearing the lungs of mucus. Avoid cough suppressants and sedatives as these interfere with mucus clearing.
• Addressing upper respiratory tract infections promptly.
• Keeping immunisations up to date.
• Encouraging reasonable physical activity, but avoiding excessive fatigue.
Respiratory infections can lead to severe illness such as pneumonia. Because of decreased activity levels and weakened cough response, mucus tends to accumulate and thicken. It can block airways, which can cause parts of the lung to collapse (atelectasis). Early treatment of respiratory illness and regular pulmonary function monitoring helps prevent pneumonia and atelectasis. Before severe complications arise, respiratory therapy can help maintain breathing stability.
Aerosol therapy delivers drugs directly into the lungs, using a nebuliser to turn liquid medication into a fine mist that you inhale for short spells several times a day. Medications include mucolytics to thin mucus; decongestants to reduce tissue swelling; antibiotics against infections; and bronchodilators to relax the airways.
Chest physical therapy
Chest percussion (clapping on the chest) and gravity drainage (inclining the body to encourage drainage), together with deep breathing and coughing, help remove accumulated mucus.
Vital capacity is how much air you can exhale with a maximum effort: it indicates the breathing reserve in your lungs. As MD progressively weakens the respiratory muscles, vital capacity decreases.
In the early stages of MD, incentive breathing exercises can improve respiratory muscle function. An incentive spirometer is used: this provides a goal volume for a deep breath and you’re encouraged to hold that volume a few seconds several times a day. Occasional deep breaths help maintain normal amounts of gases in the blood, prevent lung collapse and allow effective coughing.
“Frog” or glossopharyngeal breathing is a substitute voluntary breathing method that uses the muscles of the tongue and throat as a pumping mechanism to force air into the lungs.
Frog breathing is used effectively by many respiratory-impaired individuals for emergencies, chest expansion, coughing and time off the ventilator.
Mechanical ventilatory aids
• Intermittent positive pressure breathing (IPPB) is used several times daily for hyperinflation therapy: it helps expand collapsed parts of the lungs and increases volume. This small portable machine connects via a mouthpiece or facemask to the airway.
• A volume ventilator is used to counteract underventilating (hypoventilating) during sleep. It is larger than the IPPB machine and initially requires a nasal or face mask. It may be used also during the day as more assistance becomes necessary. A mouthpiece can be used for daytime.
• Tracheostomy is a permanent hole made in the neck below the vocal cords so a small plastic tube can be placed directly into the airway. This frees the face of attachments and allows easy connection to the ventilator, removal of secretions and direct delivery of aerosol medications. A tracheostomy doesn’t impede speaking when special valves are in place.
Muscular Dystrophy Australia. Information: respiratory. Official website www.mda.org.au