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    Home> Publications >Breathe Easy
MDA Services brochure cover   Assisted Ventilation

 


Table of Contents

Dear Friends
Introduction
Neuromuscular Diseases and Breathing
Respiratory Evaluations

Prevention
Respiratory Treatments
Assisted Ventilation
Quality of Life
For More Information


Your doctor may have recommended that you consider assisted ventilation for yourself or your child when a neuromuscular disorder, such as muscular dystrophy or spinal muscular atrophy, has weakened respiratory muscles to the point that your own efforts can’t provide adequate air exchange.

A doctor and a patient during a clinical exam.

Positive pressure devices pump air into the lungs under pressure. They’re commonly used in neuromuscular diseases.

Assisting these muscles with mechanical support is in some ways similar to assisting skeletal muscles with a brace or heart muscle with a pacemaker.

A doctor and a patient during a clinical exam.

A belt that rhythmically inflates and deflates can help push air in and out of the lungs.

WHAT KINDS OF VENTILATORY ASSISTANCE ARE THERE?

If you’re old enough to remember the polio epidemics of the 1940s and 1950s, you probably remember the term iron lung. These were in fact the first effective form of long-term ventilatory assistance, and they used a type of ventilation known as negative pressure.

For the inspiratory part of the breathing cycle, the machine created a vacuum around the patient, who was encased in a metal tube (iron lung), pulling air into the lungs. The vacuum was released to allow the patient to exhale.

This type of device still exists, in an updated and much more portable form. A plastic shell that goes around the body, and can be worn while working, studying or sleeping, is a negative pressure type of assisted ventilation.

Another variation on this theme is a belt that rhythmically inflates — pushing against the diaphragm and aiding exhalation — and deflates — allowing chest expansion and aiding inhalation.

A doctor and a patient during a clinical exam.

Iron lungs were used during the polio epidemics of the 1940s and 1950s. Photo courtesty of March of Dimes.

Today, though, devices that use positive pressure are much more common. With these devices, air from your surroundings is pumped into the lungs under pressure to simulate inhalation, with a lower pressure or no pressure during exhalation.

Positive pressure devices can deliver either a set volume, or amount, of air, with variable pressures. Or they can deliver a set pressure of air, with variable volumes. These are generally called volume-cycled and pressure-cycled ventilatory assistance devices.

Volume ventilators typically (but not always) deliver air though a surgical opening in the trachea (windpipe), which provides more direct and controllable access to the lungs. This is called invasive, or tracheostomy-delivered, ventilation.

Volume-cycled ventilators are more powerful than pressure-cycled ventilators. They can be used in people whose respiratory muscles are extremely weak.

A doctor and a patient during a clinical exam.

A tracheostomy is a minor surgical procedure that inserts a tube into the trachea (windpipe) through which air can be delivered under pressure. In some situations, a cuff needs to be kept inflated around the tracheostomy tube.


A doctor and a patient during a clinical exam.

After a tracheostomy, a tube connects the windpipe to a mechanical ventilator.


Pressure ventilators are smaller and less powerful. They typically deliver one pressure of air for inhalation and another for exhalation, so they’re called bilevel positive airway pressure, or BiPAP, devices. (Some people don’t call these ventilators at all, because they were originally used for other purposes.)

BiPAPs usually are used without a tracheostomy, although doctors sometimes prescribe a small, pressure-cycled device with a tracheostomy for a young child with small lungs.

Adolescents and adults generally use a nasal mask, mouthpiece or other noninvasive (nontracheostomy) interface with these less powerful ventilators. People who use a mouthpiece requiring conscious effort will need to switch to a mask or other interface during sleep.

A doctor and a patient during a clinical exam.

Today’s ventilators are highly portable, battery-operated devices.

Ventilatory assistance need not be full time. In fact, many people use it only during sleep at first, progressing to daytime use gradually, if necessary.

Most people whose respiratory muscles are weak enough to require assisted ventilation also require assisted coughing. The CoughAssist or a similar device is often recommended, not only during colds but on a regular basis, to prevent mucus buildup in the airways.

 
Comparison: Noninvasive & Invasive Assisted Ventilation
Factor Noninvasive System Invasive System
Mechanism air delivered through mouth or nose or by device around body air delivered to lungs below mouth and nose through opening in windpipe (trachea)
Air exchange effective for most until respiratory muscles are extremely weak effective even when respiratory muscles are nonfunctional
Protection of airway effective unless swallowing muscles are too weakto prevent inhalation of liquids or solids or when upper airway is obstructed effective for all if tracheostomy tube has a cuff that protects airway from liquids or solids
Cost generally covered by Medicare Part B or comparable insurance; some dispossable supplies may require out-of-pocket payment generally covered by Medicare Part B or comparable insurance; out-of-pocket cost for disposable supplies about $300 to $500 a month; additional long-term costs for professional caregivers
Surgery no yes (minor)
Control by user adult user controls when to use system, switch to invasive system or use no system user may lose ability to switch to noninvasive system
Infection risk no increased risk of infection if device cleaned and maintained increased risk
Inconvenience minimal; can easily be used part time need for suctioning of mucus, professional assistance, equipment sterility
Coughing user can cough, with or without mechanical or manual assistance will require coughing assistance or suction device to remove secretions from respiratory tract
Speaking minimal interference, depending on interface may interfere, especially when speaking valve can't be used
Swallowing doesn't interfere may interfere
Appearance masks and other interfaces highly visible face isn't affected; trach tube can be camouflaged
 
WHY DO THESE DEVICES USE AIR INSTEAD OF OXYGEN?

There are some diseases — mainly diseases of the lungs themselves, such as cystic fibrosis and chronic obstructive pulmonary disease — in which a low and continuous flow of oxygen is beneficial. In these diseases, the air sacs of the lungs themselves are damaged, so that oxygen has a hard time flowing across them into the bloodstream, even though the person is moving air in and out of the lungs in a normal breathing cycle. Giving more oxygen with each inhalation can help in this situation.

But in neuromuscular disease, the primary problem (unless you have a pulmonary condition in addition to a neuromuscular one) is mechanical, making breathing too shallow. What’s needed is help moving air in and out.

So, except during pneumonia or other acute illnesses, doctors usually prescribe nothing but room air — which is about 21 percent oxygen — for people with neuromuscular diseases who need ventilation.

INVASIVE OR NONINVASIVE VENTILATION?

Compared to invasive ventilation, noninvasive systems preserve natural swallowing, clearance of mucus and speaking. They don’t have any surgical openings, so they don’t lead to infections.

With a tracheostomy tube (trach) in place, mucus usually has to be suctioned out of the trach tube several times a day. The patient is vulnerable to infection because of the surgically created opening into the respiratory tract. Speaking can usually be maintained (if the person was able to speak before the trach), but it may not be completely normal. Swallowing can also be affected.

One way in which invasive systems may be superior to noninvasive is that they leave the face free of a visible device. Noninvasive systems require a visible mask, mouthpiece or other interface that some people find unacceptable.

A doctor and a patient during a clinical exam.A doctor and a patient during a clinical exam.

Some people with mild respiratory impairment find singing or playing a wind instrument helps their air exchange.


HOW DO YOU SPEAK WITH A TRACHEOSTOMY TUBE IN PLACE?

During natural speech or singing, it’s impossible to inhale. To produce sound, air has to move from the lungs up the trachea and over the vocal cords in the larynx (see illustration)

For a trach user to talk, he or she has to be able to tolerate this temporary diversion of air away from the lungs. If you can tolerate this, a speaking valve (sometimes called a Passy-Muir valve, which is a brand name) can be attached to the trach tube. When you speak, this valve diverts air up over the vocal cords instead of in and out through the trach tube.

For air to move up to the vocal cords, there also has to be an opening in or around the trach tube. A hole in the upper surface of the tube or a deflatable cuff around the tube are two ways to allow this air movement.

CAN YOU SWITCH BETWEEN NONINVASIVE AND INVASIVE SYSTEMS?

It’s a simple matter to switch from noninvasive to invasive ventilation. Switching from an invasive system to a noninvasive one is much more difficult, but it too can sometimes be accomplished. Read the “Dear Friends” message.
 
   Respiratory Care in Duchenne Muscular Dystrophy

By the time a boy with Duchenne muscular dystrophy (DMD) is in his teens — and sometimes earlier — he’ll likely experience some respiratory distress, although this may not be recognized for what it is. Interrupted nighttime sleep, excessive daytime fatigue, headaches, and trouble concentrating and thinking may be due to poor air exchange. See "Symptoms of Chronic Underventilation."

A doctor and a patient during a clinical exam.

A child with Duchenne muscular dystrophy should begin having respiratory evaluations between ages 4 and 6.

In Duchenne MD and some other muscular dystrophies, it’s important to realize that cardiacfunction is closely tied to respiratory function. A deteriorating heart muscle, also common in DMD and other MDs, can have a negative effect on breathing.

The relationship between heart function and breathing also works the other way: Respiratory abnormalities can contribute to cardiovascular problems. Doctors who study cardiomyopathy in muscular dystrophy say that using noninvasive assisted ventilation, particularly at night, helps heart function in boys with DMD.

Needless to say, poorly functioning cardiac and respiratory systems can be life-threatening. Early diagnosis, regular follow-up and early therapy for the heart or breathing problems can extend a young man’s quality of life and length of life.

In 2004, the American Thoracic Society published a set of guidelines for respiratory care in DMD. The development of these guidelines was supported in part by MDA, through a grant to Jonathan Finder in the Department of Pulmonology at Children’s Hospital of Pittsburgh.

The guidelines were written for physicians, but it’s wise for parents and young men with DMD to be aware of them, and be able to discuss them with their physicians. One of the most important recommendations is to learn about assisted ventilation options before an emergency occurs.

The guidelines also recommend that a person with DMD:

  • Undergo an evaluation of respiratory status early (between ages 4 and 6) and tests of respiratory function at every clinic visit thereafter.
  • Undergo regular cardiac evaluations starting at school age.
  • See a pulmonologist twice a year starting about age 12 or when FVC deteriorates to 80 percent of normal or less.
  • See a pulmonologist every three to six months after starting to use assisted ventilation or an airway clearance device.
  • Have cough effectiveness evaluated regularly, and learn how to use a manual cough assist maneuver or an assisted coughing device.
  • Learn how to use an oximeter at home to measure blood oxygen levels.
  • Maintain good nutrition, with a feeding (gastrostomy) tube if necessary.
The experts strongly suggest that boys with DMD begin using noninvasive ventilatory support at night when breathing becomes insufficient during sleep or overnight blood oxygen measurements are below normal. When daytime breathing becomes inadequate, they should add noninvasive ventilation during the day.

When these methods begin to lose effectiveness, the young man and the family should consider the option of a tracheostomy.

The guidelines warn that supplemental oxygen shouldn’t be used to treat inadequate breathing during sleep unless ventilatory assistance is also being used. And they caution against starting mechanical ventilation before it’s required. Doing so can interfere with adequate respiratory monitoring and lead to a false sense of respiratory security.

 
 

 Respiratory Care in ALS

In most people with amyotrophic lateral sclerosis (ALS), respiratory muscles deteriorate as the disease progresses, because the nerve cells that control these muscles are lost. This deterioration leads to decreased air exchange. The results usually include shortness of breath when the person is lying down or with exertion, and interference with sleep – all signs of respiratory distress.

A doctor and a patient during a clinical exam.

Regular measurements of respiratory function are crucial for people with ALS.

Another effect of weak intercostal muscles in ALS is a decrease in the person’s ability to cough; infections can result. Manual or mechanical assisted coughing is usually recommended.

In addition, the nerves and muscles that control swallowing, as well as routing of food and liquids into the stomach and air into the lungs, are often affected. This can lead to inhaling of food or liquids, with resulting airway obstruction or infection. This type of problem may be solved by inserting a feeding (gastrostomy) tube so that the person isn’t eating and drinking by mouth.

In 1999, the American Academy of Neurology published guidelines for physicians providing respiratory care in ALS. People with ALS can follow these recommendations and discuss them with their doctors.

  • Watch for and report signs of respiratory muscle loss and decreased air exchange (see "Symptoms of Chronic Underventilation")
  • Undergo frequent measurements of respiratory function.
  • Begin noninvasive ventilation to relieve symptoms and to some extent prolong survival.
  • Begin invasive (tracheostomy-delivered) ventilation if long-term survival is the goal, taking into account the burdens and benefits of this decision (see "Invasive or Noninvasive Ventilation")
The guidelines also advise doctors that the ALS patient maintains the right to refuse or withdraw treatment, including mechanical ventilation. While ventilation is being withdrawn, doctors should provide access to adequate pain medications (including morphine) and anti-anxiety drugs.

 
 
 
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