Iron lung

The invention: Amechanical respirator that saved the lives of victims
of poliomyelitis.
The people behind the invention:
Philip Drinker (1894-1972), an engineer who made many
contributions to medicine
Louis Shaw (1886-1940), a respiratory physiologist who
assisted Drinker
Charles F. McKhann III (1898-1988), a pediatrician and
founding member of the American Board of Pediatrics
A Terrifying Disease
Poliomyelitis (polio, or infantile paralysis) is an infectious viral
disease that damages the central nervous system, causing paralysis
in many cases. Its effect results from the destruction of neurons
(nerve cells) in the spinal cord. In many cases, the disease produces
crippled limbs and the wasting away of muscles. In others, polio results
in the fatal paralysis of the respiratory muscles. It is fortunate
that use of the Salk and Sabin vaccines beginning in the 1950’s has
virtually eradicated the disease.
In the 1920’s, poliomyelitis was a terrifying disease. Paralysis of
the respiratory muscles caused rapid death by suffocation, often
within only a few hours after the first signs of respiratory distress
had appeared. In 1929, Philip Drinker and Louis Shaw, both of Harvard
University, reported the development of a mechanical respirator
that would keep those afflicted with the disease alive for indefinite
periods of time. This device, soon nicknamed the “iron lung,”
helped thousands of people who suffered from respiratory paralysis
as a result of poliomyelitis or other diseases.
Development of the iron lung arose after Drinker, then an assistant
professor in Harvard’s Department of Industrial Hygiene, was
appointed to a Rockefeller Institute commission formed to improve
methods for resuscitating victims of electric shock. The best-known
use of the iron lung—treatment of poliomyelitis—was a result of
numerous epidemics of the disease that occurred from 1898 until the 1920’s, each leaving thousands of Americans paralyzed.
The concept of the iron lung reportedly arose from Drinker’s observation
of physiological experiments carried out by Shaw and
Drinker’s brother, Cecil. The experiments involved the placement
of a cat inside an airtight box—a body plethysmograph—with the
cat’s head protruding from an airtight collar. Shaw and Cecil Drinker
then measured the volume changes in the plethysmograph to identify
normal breathing patterns. Philip Drinker then placed cats paralyzed
by curare inside plethysmographies and showed that they
could be kept breathing artificially by use of air from a hypodermic
syringe connected to the device.
Next, they proceeded to build a human-sized plethysmographlike
machine, with a five-hundred-dollar grant from the New York
Consolidated Gas Company. This was done by a tinsmith and the
Harvard Medical School machine shop.
Breath for Paralyzed Lungs
The first machine was tested on Drinker and Shaw, and after several
modifications were made, a workable iron lung was made
available for clinical use. This machine consisted of a metal cylinder
large enough to hold a human being. One end of the cylinder, which
contained a rubber collar, slid out on casters along with a stretcher
on which the patient was placed. Once the patient was in position
and the collar was fitted around the patient’s neck, the stretcher was
pushed back into the cylinder and the iron lung was made airtight.
The iron lung then “breathed” for the patient by using an electric
blower to remove and replace air alternatively inside the machine.
In the human chest, inhalation occurs when the diaphragm contracts
and powerful muscles (which are paralyzed in poliomyelitis
sufferers) expand the rib cage. This lowers the air pressure in the
lungs and allows inhalation to occur. In exhalation, the diaphragm
and chest muscles relax, and air is expelled as the chest cavity returns
to its normal size. In cases of respiratory paralysis treated with
an iron lung, the air coming into or leaving the iron lung alternately
compressed the patient’s chest, producing artificial exhalation, and
the allowed it to expand to so that the chest could fill with air. In this
way, iron lungs “breathed” for the patients using them.Careful examination of each patient was required to allow technicians
to adjust the rate of operation of the machine. Acooling system
and ports for drainage lines, intravenous lines, and the other
apparatus needed to maintain a wide variety of patients were included
in the machine.
The first person treated in an iron lung was an eight-year-old girl
afflicted with respiratory paralysis resulting from poliomyelitis. The
iron lung kept her alive for five days. Unfortunately, she died from
heart failure as a result of pneumonia. The next iron lung patient, a
Harvard University student, was confined to the machine for several
weeks and later recovered enough to resume a normal life.