The Iron Lung and Polio, by Dr. Mark Rockoff.
Poliomyelitis, commonly referred to as polio, is a frightening, contagious viral disease
that can have devastating effects on the central nervous system.
Children are most often affected, but adults can also be vulnerable as scene when future
president, Franklin Delano Roosevelt, became infected in 1921 at the age of 39.
Though this illness has likely been around for millennia, it became more prevalent in
the early to mid 1900s, as large epidemics occurred around the world.
Ironically, these often happened in developed nations, including the United States, as improved
sanitation led to reduced naturally acquired immunity.
Many children who were infected developed a fever and soon were unable to move their
limbs.
Some had such extensive involvement of their spinal chord that they also could not breathe
effectively.
When this occurred, death often resulted from respiratory failure.
For many, little other than comfort measures were available for treatment.
However, Philip Drinker, an engineer at the Harvard School of Public Health, developed
a simple, mechanical ventilator that could be used to provide effective respirations
for individuals who were too weak to breathe on their own.
This large device, which because of its construction became known as an iron lung, was first used
to treat an eight-year-old girl with polio in 1928 at Boston Children's Hospital adjacent
to the Harvard School of Public Health.
Soon thereafter, iron lungs were being mass produced and used to treat polio patients
around the world.
In the early 1950s, during the last large polio epidemics that occurred, much of Boston
Children's Hospital was devoted to treating polio victims.
However, due to the pioneering research work of John Enders, a microbiologist at Boston
Children's Hospital, and his colleagues at the hospital, techniques were developed to
culture the polio virus in the laboratory.
This enabled Dr. Salk and Sabin to develop vaccines that rapidly led to the eradication
of this deadly disease.
And in 1954, Drs.
Enders, Weller, and Robbins received the Nobel Prize in medicine for their work.
By the 1980s, iron lungs were virtually obsolete, having been replaced by much smaller and less
cumbersome mechanical ventilators that are now used to treat patients with respiratory
failure from other causes.
In order to appreciate how an iron lung functions, the archives program at Boston Children's
Hospital has restored an old lung and created this short video.
This is a restored Emerson model iron lung, originally manufactured in Cambridge, Massachusetts.
An iron lung is, I think, aptly named, because it is quite a heavy and somewhat unwieldy
device.
It is made out of iron parts.
And it is very bulky and large, and it's very difficult to move around.
It often takes two or sometimes three people to push these big devices.
A patient with respiratory failure was placed inside the device by opening the front end
and sliding out a small bed.
The bed was reinserted into the machine, and the device closed and sealed.
A collar was then secured around the patient's neck to establish an airtight seal.
Depending upon the strength of their respiratory muscles, some of them had to be in there 24
hours.
Some were in at night only.
Some were in for two or three hours at a stretch, and then they would be out for half an hour.
Boston Children's Hospital even developed a room size iron lung that could accommodate
several patients at one time, as seen here with nurses inside and outside the room.
The iron lung worked by generating negative pressure within the device when a large diaphragm
at the far end of the machine pulled back.
And this would draw air into the patient's lungs via the mouth and nose, which were extended
outside the machine.
By rhythmically moving the diaphragm of the iron lung, negative pressure could be generated,
simulating natural respirations.
The rate of ventilation and the extent of negative pressure generated by the machine
were controlled with adjustable knobs.
The device was powered by electricity but could be operated manually during a power
failure.
Smart engineers back then thought there should be a mechanism to have these iron lungs operate.
So there's actually a very large lever that you can pull back and forth so that you can
physically move the bellows in and out of the iron long to create the negative pressure.
It also has a place for your foot because again, to really generate the pressure that
the patient might need, you would have to use a fair amount of force.
So you had your foot and your upper body strength to do that.
Operating the diaphragm by hand took much work and was tiring.
Hospital staff were trained to relieve each other every few minutes in order for the patient
to effectively ventilate.
It could be many hours to facilitate unimpeded ventilation.
When you got into the rhythm, you sort of counted the rhythm.
It was counted and you just picked it up and you continued to pump.
During this time, limited access to the patient's body was possible through portals in the side
of the iron lung.
The portals maintained an airtight seal after a caregiver's hands were inserted.
This enabled nurses to keep the patient clean and comfortable.
Physical therapists prevented patients from developing muscle contractions in weak limbs.
To see how negative pressure mechanical ventilation works, one merely needs to observe a patient
in an iron lung trying to speak.
When the machine's diaphragm extends to create negative pressure within the iron lung, air
is sucked into the patient's lungs and the patient is unable to speak.
Then, as a patient exhales, sound can be produced.
Here you can hear a healthy volunteer inside an iron lung counting while the iron lung
is operational.
OK, let's hear you count to 20.
Two, three, five, six, eight, nine.
Note localization is only effective during that part of the ventilator's cycle when exhalation
occurs.
Iron lungs did their work back when technology wasn't available, or more sophisticated--
we certainly didn't have the microchip back then.
And this was really the best way to support patients' respiratory function.
Fortunately, the widespread utilization of polio vaccine since 1955 has resulted in the
disappearance of polio in all but a few, remote, underdeveloped regions of the world.
Families no longer have to fear their children will suddenly be affected by this dreadful
disease.
And the few remaining iron lungs are now medical artifacts.
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