Ventilatory Assistance Devices Health Article

Definition

Ventilatory assistance devices are mechanical devices that help a person breathe by replacing some or all of the muscular effort required to inflate the lungs.

Description

Ventilation is the process of inflating and deflating the lungs in order to breathe. Normally, a person uses several sets of muscles to accomplish this—the diaphragm at the base of the lungs, the muscles between the ribs (intercostals), and, to a small extent, the muscles of the lower neck and shoulder area. When these muscles are weakened through disease or injury, the ability to ventilate is impaired. As a result, a person cannot get sufficient oxygen into, and carbon dioxide out of, the lungs in order to maintain appropriate levels in the blood. In addition, weakened ventilation muscles also impair the ability to cough, which is an essential part of clearing lung secretions and preventing infection.

Ventilatory assistance devices may be needed due to:

• muscular dystrophies (progressive muscle weakening disorders)
• amyotrophic lateral sclerosis (ALS), a progressive disease causing muscle weakness
• polio
• high spinal cord injury (injury to the spinal cord in the neck)
• Guillain-Barré syndrome (a rapidly progressive but reversible loss of muscle control)
• myasthenia gravis, acute crisis (MG is a muscle-weakening disease, in which patients may experience a "crisis" of rapid and dangerous loss of muscle strength)
• head trauma
• botulism (poisoning by botulinum toxin, usually from improperly preserved food)
• tetanus (poisoning by tetanus bacteria, usually by a deep puncture wound)

Nighttime ventilators are also used for people with obstructive sleep apnea. This is a condition in which breathing is impaired during sleep by obstructions in the airway, most often extra tissue at the rear of the throat.

Ventilatory assistance is not the same as supplying extra oxygen, as is done for people whose lungs are damaged. The person who needs ventilatory assistance generally has normal gas exchange capacity, and simply needs help moving air in and out. Supplemental oxygen can worsen the situation in such cases, as it may depress the normal signals from the brain to stimulate breathing.