Ventilator
Mechanical ventilation is required when a patient's spontaneous efforts are unable to sustain adequate ventilation of the lungs.
Invasive methods may be needed for patients who are unable to use noninvasive methods.
Ventilators perform one of the most complex functions of the body-ventilation, a process in which the lungs take in and disperse oxygen the body needs and gather up and expel the carbon dioxide created as a result of body functions. In healthy people, this gas exchange takes place in the small air sacs of the lungs, called alveoli, and, in the course of one day, normally involves 8,000 to 9,000 liters of air breathed in through the nose or mouth and 8,000 to 10,000 liters of blood pumped through the lungs by the heart.
The idea of mechanical ventilation is not new: Earnest efforts date to the mid-1800s, when devices resembling steam cabinets and phone booths were used to maintain breathing by decreasing the air pressure inside the machine. A well-known device that applied this "negative-pressure" principle was the iron lung, which was widely used in the United States from the late 1920s into the 1950s, particularly for polio patients. However, these devices were large, and they greatly restricted patient movement.
In the late 1950s, "positive pressure" ventilators, which force air into the lungs, were introduced.
Like their predecessors, modern ventilators function to deliver breaths of oxygen-enriched air to the body and remove carbon dioxide. But unlike in the past, most ventilators today are computer-controlled, functioning in complex ways to produce positive-pressure ventilation that more closely matches patients' breathing needs.
Until about the early 1990s, modern ventilators required an artificial airway, usually a tube placed through a hole surgically created into the patient's throat or a tube passed through the patient's nose or mouth.
More recently, noninvasive positive-pressure ventilators that allow for gas exchange through a face or nose mask have become popular.
Dan Van Hise, marketing manager for Siemens Medical Systems Inc. and a registered respiratory therapist who worked in patient care for a number of years, says that already in the span of his career, he's seen vast improvements in ventilators.
"The older vents-like the ones of the early 1980s-required a lot of respiratory work on the patient's part," he says, referring to the increased workload of the muscles that assist with breathing. "Today, it's not nearly the same. [Using a ventilator] is almost effortless.
"One of the biggest misconceptions from the general public is that it looks uncomfortable for the patient," he adds. But, he says, because of advancements in technology-such as computerization of ventilators, improved communication devices for patients whose speech is hampered by some medical equipment, and improved medicines for alleviating the discomfort of tubes inserted into the body-that's not always true anymore. "[Ventilator] patients are much more comfortable."
Edward Anthony Oppenheimer, MD, FCCP, Pulmonary Medicine, Los Angeles, CA
The purpose of the ventilator is to assist breathing when the respiratory muscles are weak due to amyotrophic lateral sclerosis (ALS). This should relieve respiratory symptoms and allow improved nighttime sleep; it also provides life-support. People with ALS in the past have often died due to respiratory muscle weakness and inability to breathe.
Good care today, including assistive technologies (such as a ventilator, a PEG, mobility devices, communication equipment, etc. – as needed) can allow people with ALS to continue their lives as long as they wish. As informed adults, they also have the legal and ethical right, in the United States, to stop any treatment when it is no longer desired. Most people using long-term ventilation at home, with good caregiver support, report that they are satisfied and wish to continue; they find ways to stay engaged in living without continually focusing on those things they cannot do anymore.
ALS does not directly affect the heart or circulation. Thus, if nutrition and breathing are maintained, the heart function should not be affected. Everyone is at risk of coronary heart disease eventually. So some people with ALS on long-term ventilation will eventually have a heart attack, but this is not related to ALS.
Our experience with antibiotics is that frequent use may result in infections more and more resistant to antibiotics. Therefore emphasis on good nutrition and good clearance of airway secretions usually allows people with ALS to avoid frequent antibiotic-requiring infections. Sometimes people do not give enough attention to assistive cough techniques to clear airway secretions (physicians and respiratory therapists often have neglected this as well). With good care, people with ALS who stay socially active and engaged in life can survive using mechanical ventilation for many, many years. Survival for over 10-15 years is possible.
Also remember that informed choice allows PALS to decide how much treatment, or how little, they wish – and if they want to stop any or all treatment at some point. It is very important that family members find ways to maintain balance in their lives too. This usually means that personal assistants need to be carefully selected, hired and trained to help with care, allowing family members to continue their work and other goals as well.
Ideally a person with ALS maintains social involvement and many interests, living at home and also getting out to do activities of interest in the community. Some people with ALS have written about the details that have made living with ALS successful; you will find these accounts in biographies they have published as well as comments on various e-mail discussion groups and Web sites. Not everyone can do this successfully, but it is certainly a path I encourage my patients to seriously consider.
Edward Anthony Oppenheimer, MD, FCCP,
Pulmonary Medicine, Los Angeles,
CA