Taleah English, 3, of Orem, Utah, has SMA type 1. She's "suctioning" her bunny, who shares her BiPAP noninvasive ventilation device. Preface Muscular Dystrophy Affects Breathing Respiratory Therapy: Treatments, Techniques, Equipment For More Information Pulmonary Monitoring and Treatment Plan

RESPIRATORY THERAPY: TREATMENTS, TECHNIQUES, EQUIPMENT

The result of weakening respiratory muscles is that the "vital capacity" of the lungs (the amount of air that a person can exhale after taking in a deep breath) decreases over time. The "forced vital capacity" — a measurement of how much air one can exhale with a maximum effort after taking in a deep breath — is based on your child's weight, height and age (see Pulmonary Function Testing). A normal capacity is 75 percent or greater of the "predicted," or normal, number for a person of a specific height, weight and age. The forced vital capacity is important because it indicates how much breathing reserve exists in the lungs.

Occasional deep breaths are vital in maintaining normal amounts of oxygen in the blood. Deep breaths prevent the smallest parts of the lungs from collapsing. Deep breaths are also necessary for effective coughing, which is the body's natural mechanism for removing mucus from the lungs. The cough reflex is an explosive expulsion of a volume of air from the lungs. The high pressure and speed of this air propel irritants, such as mucus, up and out of the lungs. Neuromuscular disorders can weaken the cough effort, which is vital in removing mucus during an acute respiratory infection.

Exercises for Breathing Muscles: Incentive Spirometry

The primary focus of respiratory therapy applied to children with neuromuscular disorders is to assist in reducing the speed at which the vital capacity decreases. This is accomplished in stages over the progression of the disease with different methods of mechanical ventilatory assistance. Your doctor may or may not recommend one or more of the following treatments.

In our clinic, we've found that in the early stages of MD incentive breathing exercises are helpful. These exercises motivate the child to take "sigh breaths" — breaths two to four times larger than a regular breath. The amount of air in a regular breath is called a "tidal volume" breath. Tidal breathing without sighing doesn't allow total inflation of all the air sacs ("alveoli") in the lungs and can lead to the closing off of these sacs ("atelectasis").

An "incentive spirometer" is used to help open alveoli. The device provides a goal volume for a deep breath and the child is encouraged to hold that volume for 10 to 15 seconds. Fifteen to 20 deep breaths are suggested four to six times per day. Practicing this deep breathing exercise without the spirometer every hour or two would be ideal. Children are encouraged to begin this form of respiratory therapy when their vital capacity measurement falls below 75 percent of the normal, or predicted, value.

The use of incentive breathing exercises is something that we individualize very carefully with each patient. The goal is simply to try to provide a substitute for the loss of "sigh breaths." We do not believe that we are making muscles "stronger." As we see muscles weaken by objective pulmonary function tests, incentive breathing exercises are discontinued in favor of other breathing assistance techniques.

Aerosol Therapy: Nebulizers, Metered-Dose Inhalers

Aerosol therapy is a method of delivering medications directly into the lungs. Specific medications that your doctor may prescribe include:

A nebulizer turns the liquid medication into a fine mist that can be inhaled. A small air compressor is attached to the nebulizer to generate a flow of air. Your child simply breathes slowly and deeply through the nebulizer for 15 to 20 minutes three to four times a day.

Another method of delivering medication directly into the lungs is the metered-dose inhaler (MDI). An MDI is a small, hand-held, plastic container of medication frequently attached to a "spacer" (a 6-inch cylindrical chamber and mouthpiece).

An aerosol treatment program is designed to meet the particular needs of your child during an acute respiratory illness. The pulmonary medicine team will assist parents in learning how to administer aerosol therapy and how to obtain the proper equipment.

Cough Therapy: Intrapulmonary Percussionator, Emerson In-Exsufflator

The "intrapulmonary percussionator" can be employed to assist in mucus clearance during an acute respiratory tract infection. This equipment is used when the vital capacity has declined, the child uses a wheelchair full time, and therapy must be performed in one body position.

In-Exsufflator (Photo courtesy of Respironics, Pittsburgh, PA)

An in-exsufflator, also called the CoughAssist, is a small electrical machine that can assist a weak cough effort and make it effective in expelling mucus. The device can push a volume of air into the lungs and quickly pull that same volume of air out of the lungs, imitating a strong cough effort. As with any respiratory therapy equipment, the pulmonary medicine team will assist parents in learning equipment operation.

We have found that the CoughAssist is a very valuable device and initiate its use at some point with all of our patients when the clinical picture and pulmonary function tests dictate.

Mechanical Ventilatory Assistance: Volume Ventilators

Modern "volume ventilators," which deliver a preset volume (amount) of air to the child with each breath, are valuable in the treatment of children with MD-related respiratory problems.

When the vital capacity has dropped below 40 percent of normal, a volume ventilator may be used during sleeping hours, a time when the child is most likely to be underventilating ("hypoventilating"). Hypoventilation during sleep is determined by a thorough history of sleep disorder with an oximetry study and a capillary blood gas (See Pulmonary Function Testing). The ventilator requires a nasal or face mask for connection to the airway. The masks are constructed of comfortable plastic with Velcro straps to hold them in place during sleep.

Nasal mask ventilation

As the vital capacity declines to less than 30 percent of normal, a volume ventilator may also be needed during the day for more assistance. The child gradually will increase the amount of time using the ventilator during the day as needed. A mouthpiece can be used in the daytime and a nasal or face mask can be used during sleep. The machine can easily fit on a ventilator tray on the bottom of a power wheelchair.

There may be times — such as during a respiratory infection — when a child needs to rest his/her respiratory muscles during the day even when not yet using full-time ventilation. The versatility of the volume ventilator can meet this need, allowing tired breathing muscles to rest and also allowing aerosol medications to be delivered.

Mechanical Ventilatory Assistance: Pressure Ventilators

Some physicians and therapists recommend a different type of ventilation device — one that delivers air at a preset pressure instead of a preset volume. The type of device most often used is called a "BiPAP," which is short for "bilevel positive airway pressure." This machine delivers a set level of positive-pressure air during inspiration and can deliver a lower level of pressure during expiration. The volume delivered per breath is unknown, or variable. Furthermore, the volume changes dramatically with changes in lung stiffness and when airways are clogged with secretions from an infection. A nasal or face mask can be used for connection to the airway.

While mechanical ventilatory assistance must be individualized to the needs of each patient, we have found the vital capacity to be a useful guide, along with the clinical picture. Furthermore, we have found volume ventilators to be much more effective than pressure ventilators in neuromuscular disease.

Alternative Airway Connection: Tracheostomy Tube

Tracheostomy ventilation

When a volume ventilator is needed during the day as well as at night, alternate approaches to airway connection can be considered. However, many patients who require both day and nighttime ventilation continue to utilize nasal, oral and face mask attachments successfully.

Wearing the plastic nasal or face mask during the day may interfere with attending school and social contact with family and friends, and may cause skin irritation due to constant skin pressure. A mouthpiece may not be tolerated because of weakened facial muscles or air leakage. Sometimes an alternative must be considered.

The most commonly considered alternative approach to airway connection is a tracheostomy. A tracheostomy is a small, permanent incision in the neck just below the vocal cords which allows a small plastic tube (tracheostomy tube) to be placed directly into the airway. This keeps the face free of encumbrances and permits an easy connection to the ventilator.

A "trach" may interfere with speaking. Many children can vocalize using the air that can leak around the tracheostomy tube. A special valve (Passy-Muir valve) can be used to allow exhaled air to go around the tracheostomy tube and pass through the vocal cords to improve voicing as much as possible. Advantages of a trach include:

A tracheostomy tube requires careful attention to hygiene in order to prevent infection. Excessive secretions can be removed with a tiny tube ("catheter") attached to a suction machine. Caregivers must be instructed in sterile techniques for suctioning. Because the nose, through which air from the outside world is normally moisturized, has been bypassed, most people will need humidification, at least on a part-time basis. The sensation of taste may be diminished.