Asthma clings to you wherever you go

I found a good quote that pretty much describes the life of the asthmatic:

And even in the intervals of health the asthmatic's sufferings do not cease:  he seems well, he goes about like his fellows and among them, but he knows that he is altogether different from them; he bears about his disease within him wherever he goes; he knows he is struck -- "haeret lateri lethalis arundo;" he is conscious that he is not sound -- he cannot be warranted; he is not certain of a day's, perhaps not of an hour's health; he only knows that a certain percentage of his future life must be dedicated to suffering; he cannot make an engagement except with a proviso, and from many of the occupations of life he is cut off; the recreations, the enjoyments, the indulgences of others are not for him; his usefulness is crippled, his life is marred; and if he knows anything of the nature of his complaint, he knows that his sufferings may terminate in a closing scene worse only than the present."  Henry Hyde Salter.

Source:  Salter, Henry Hyde, "On Asthma: It's Pathology and Treatment," 1882, New York, page 2

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Note:  "haeret lateri lethalis arundo," is Latin.  Translated into English it means "in her side still clings that deadly shaft."  Or, worded another way by eudict.com:  "The deadly arrow sticks in her (his) side."  Asthma is like the deadly arrow that clings to her side wherever she goes.  Asthma clings to you no matter where you go, no matter what you do.  It's always there hovering over you like a dark, ominous cloud.  

According to http://www.proz.com, it comes from Virgil's Aenid (book 4, string 73):

Sick with desire, and seeking him she loves, From street to street the raving Dido roves. So when the watchful shepherd, from the blind, * Wounds with a random shaft the careless hind, * Distracted with her pain she flies the woods, Bounds o'er the lawn, and seeks the silent floods, With fruitless care; for still * the fatal dart Sticks in her side *, and rankles in her heart.

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30,000 B.C.: The birth of allergies

Surely allergies have been around since the beginning of human existance.  Dr. Paul M. Ehrlich explained one theory in which allergies are believed to be "a leftover survival tactic" whereby ancient people living along the Tigris and Euphrates Rivers where repeatedly exposed to harmful germs such as bacteria and parasites.  (1)

Ehrlich said that back then, perhaps as far back as 30,000 years before the birth of Christ, our immune systems needed to be powerful to fight off these germs.  The people with the strongest immune response survived while others died.  "So," he said, "being an allergic person may have been an advantage." (1)

Yet today we have many defenses against such invaders, such as shoes, clothing, clean drinking water, processed food, vegetables that are treated with pesticides, air conditioned buildings, etc.  We receive vaccinations and use hand sanitizers.  People today simply aren't exposed to germs, so the allergic response isn't needed.

For most of us, our immune systems have adapted to the change.  Yet for some of us our immune systems continue to work overtime.  Lacking harmful germs to occupy our immune systems, they become bored and develop a sensitization to things that are supposed to be safe, such as dust mites, pollen, molds, and cockroach urine.

So this is the basis of why about 10 percent of the world's population develop allergies.

The rest of my history of allergies will be published on this blog in April of 2014.

For a complete history of allergies and asthma click here.

References:

1. Ehrlich, Paul M., Elizabeth Shimer Bowers, "Living with Allergies," 2009, page 6

History of the great bronchodilator Ephedrine

A long, long time ago -- three thousand years be exact -- in a land far, far away and isolated from the rest of the world by mountains, water, and a huge wall, sat a shirtless boy leaning forward in a crouched position, arms pressed against the floor supporting his shoulder's high.  With each breath his shoulders were sucked in, skin drawn taught.

A elderly man proffered a cup to the boy.  "Drink this, my son."

The boy frantically grabbed the cup from the elderly man and eagerly drank between gasps for air.  The drink was yellow; the taste bitter.  Yet he drank up knowing it was worth it. Within moments his heart was racing and pounding in his chest. Soon thereafter he could inhale a quarter of a breath, and then a full breath.  It felt so good.

This was life for lucky asthmatics who lived around 1500 B.C. in Ancient China.  A plant called Ma-Huang was used to treat a variety of ailments, especially breathing trouble.  Ancient Chinese asthmatics were lucky because this remedy was the most effective in all the ancient world for treating asthma.

While ephedrine and it's medicinal uses were described as far back as 6,000 B.C, credit for the first use of the herb was reported in ancient China.  Legacy has it that about 2700 B.C Chinese Emperor Shen Nung tasted hundreds of herbs to test their medicinal value, according to U.S. National Library of Medicine. 

One of the herbs he's believed to have tasted was ma huang.  It was listed in a medical book believed to be written by Shen called Shen-nung pen ts'ao ching (Divine Husbandman's Materia Medica).  This book listed 265 medicines, their doses, how to prepare them, and their uses.  Yet while Shen is given credit as the author, the true author (or authors) is unknown, according to U.S. National Library of Medicine.

Ma Huang became a classic remedy in Ancient China as a diaphoretic (it made you pee, which is good if you have fluid in your lungs making it hard to breathe), heart stimulant, antipyretic (it reduced fevers), cough reducer, nasal decongestant useful for colds and other breathing disorders such as asthma (although it wasn't called asthma by the ancient Chinese). 

Ma Huang is a product of a plant we now refer to as Ephedra Seneca, which is a shrub that reaches 60-90 cm high with a green, slender and somewhat flexible stem that is ribbed and channeled.  The stems are removed and beaten to separate them, and then they are dried in the sun.  A bitter tasting yellow powder is produced that is soluble in water, so it was often mixed with tea. 

Over 50 varieties of the species are available around the world, and it's indiginous to subtropical desserts and mountainous regions such as America, Europe and Asia.  Ephedra is also available in other unrelated plants such as sida cordifolia, according to Monchair S. Ebadi in his book "Pharmacodynamic basis of herbal medicine (2007, page 312)

Tea was a common drink of the Ancient Chinese, and rumor had it that Emperor Shen Nung was boiling water one day and a tea leaf landed in the pot.  He drank it and loved the flavor.  So Nung made popular both the asthma remedy and the tea to which it was delivered.  However, Ma Huang could also be eaten or smoked.

The plant Ephedra gerandiana grew in India and Pakistan.  The stems were cut, beaten, dried and used to treat various diseases.  Ephedra edistachya and Ephedra evulgaris were available in Europe, and there are recordings of the Russians using Ephedra for respiratory disorders and rheumatism, according to Steven B. Karch, in his book "Karch's Pathology of Drug Abuse," (Florida, 2009, page 241).

Pliney the Elder, who was Roman author from 23-79 A.D., wrote about Ephedra and it's medical uses.  Pliney wrote a lot about asthma, and it's possible he may have prescribed Ephedra as one of the remedies to help people breathe better.  So Ephedra was available to the Ancient Romans. 

Karch described that in the 1600s Native America Indians and Spaniards in the American Southwest used ephedra derived from the plant Ephedra nevedensis.  Only they used the plant to alleviate urinary incontinence and venereal diseases such as syphilis. 

Settlers in the American West, Karch wrote, brewed ephedra teas that were referred to by a variety of names including yellow tea or chaparrel.  When the Mormon's arrived in Utah they were introduced to Ephedra tea by local Indian tribes, and this is one reason it's often referred to as Mormon tea. 

While ephedra was used by various societies, and continued to be used even up to modern times by the Chinese, it was not introduced into the West until 1885 when Yamanashi isolated the active ingredient.  A few years later in 1887 Nagayoshi Nagai isolated an alkaloid in Ephedra vulgaris, which is a genus of the plant that grows in Europe. 

Nagai gave this alkaloid the name ephedrine and is given credit by history for it's discovery.  A few years later another chemist also isolated it.  Nagia and others did extensive studies on the alkaloid and discovered that it's a stimulant for the central nervous system, and circulatory system.  It was also found to dry secretions, and was effective for runny eyes and runny noses, or as a nasal and chest decongestant.  It was also proven to be a dilator of smooth muscles that wrap around the lungs and gastrointestinal tract.

While not commonly known, ephedra was actually the best asthma treatment until 1901 when adrenaline was discovered. If communication was what it is today thousands of years ago, asthmatics wouldn't have had to suffer for so many years.  In fact, even while ephedrine was being used in the West to treat asthma in 1901, it didn't hit the market until 1926.

Karch describes how representatives for the pharmaceutical company Merck followed Nagia's research closely hoping to add this new medicine to the market and profit from it, and it did so.  But the product they produced didn't sell well and the products were all but abandoned until 1926 when Chen and Schmidt read a report they wrote about the alkaloid and it's uses to the Section on Pharmacology and Therapeutics.

Chen and Scmidt described ephedrine as a top line asthma medicine. They actually believed ephedrine was as effective as epinephrine, yet it was later learned this was not true. 

After Chen and Scmidt's report sales of ephedrine skyrocketed so fast that there was concern demand would top supply.  So the march was on to find if a synthetic ephedrine (this means it can now be produced in a factory and is called racemic ephedrine) could be produced.

While ephedrine was synthesized that same year, the ephedrine shortage never occured.  The medicine was then approved by the American Medical Association as a bronchodilator that was safer to use than epinephrine, and was later available as an over the counter option.  Racemic ephedrine was marketed under the name Ephetonin.

By the 1930s ephedrine -- like epinephrine -- was available by either injection or hand held nebulizer, according to Greg Mitman in his book, "Breathing Space" (London, 2007, page 232).  By 1954 it was available as an over the counter medicine and marketed as an asthma remedy and nasal decongestant.

The ephedrine solution was called ephedrine sulfate. 

Pseudonephrine is another alkaloid derived from ephedra plants, only it's cardiac effect was much less than ephedrine.  For this reason pseudinephrine was marketed as an over the counter nasal decongestant.  A common brand is sudafed.

Popular ephedrine product available as an over the counter remedy in the 1960s were Franol and Franol Plus (which also contained theophylline, a bronchodilator, to ease breathing), according to Mark Jackson in his book "Allergy:  The History of a Modern Malady" (London, 2007, pages 126 and 127).

Jackson wrote that Franol was a combination of ephedrine, theophylline and a barbituate and was marketed as an asthma, bronchitis and hay fever remedy.  Franol plus was the same with the addition of an antihystamine for those also suffering from allergies. 

Other alkaloids discovered from ephedra plant and similar in structure to ephedrine and pseudonephrine are amphetamines and methamphetamines.  The affects of these alkaloids are similar to cocaine, in that they stimulate the central nervous system, boost metabolism, decreases appetite, and enhance performance.  They can create euphoria if used in high doses, can be addicting, tolerance can build up over time, and overdosing can result in cardiac side effects including death. Long term use can result in heart muscle damage and death. 

In the rush to create a synthetic ephedrine in 1927 it was discovered how to turn ephedrine into ampthetimines and methamphetamines.  Sales of ephedra products skyrocketed in the 1990s as the medicine was used as a weight loss product and as a performance enhancer by athletes.  Abuse of the medicine resulted in several reported deaths (although some experts doubted ephedrine was the cause).

Another reason sales spiked in the 1990s is people learned how to make amphetamines and methamphetamines out of over the counter pseudonephrine and ephedrine products.  This abuse encouraged the Food and Drug Administration to ban over the counter sales of the ephedra in 2004, and pseudonephrine products are still available but are monitored closely by pharmacists.

Ephedrine is really no longer needed as a nasal decongestant nor as an asthma remedy as far better and safer treatments are now available.  In fact, it's usefulness waned years before it was banned as an over the counter medicine. 

Yet if your physician believes you'll benefit from this medicine it's still available as a prescription, and it's not illegal if you posses it.  It's rarely prescribed, however.

Theophylline no longer top line asthma medicine

In 1976 my pediatrician started prescribing Sustair, a liquid theophylline to control my asthma.  I remember my mom feeding me that stuff with a teaspoon, and it tasted nasty.  For the next 30 years I was chronically dependent on theophylline, although ultimately I was able to take the pill version called Theo-Dur or some generic version.

In his 1807 book, "A practical inquiry into disordered respiration: distinguishing the species of convulsive asthma, their causes and indications of cure," Dr. Robert Bree recommended coffee as one of the best remedies for asthma, and listed various physicians who likewise recommended it. 


For example, he wrote that "Sir J(ohn) Floyer used it with great benefit in the later part of his life, as appears from the account of Dr. Musgrave."  (1)

In the 1860s Dr. Henry Hyde Salter wrote a book, "On Asthma," and he recommended strong coffee and tea to help control hardluck asthma.  He believed sleep favored asthma and coffee helped keep you awake.  (2) With Salter as his doctor, this was a remedy occasionally tried by a young asthmatic Teddy Roosevelt.  (3)

Salter may have known coffee was a member of the xanthine family, but he probably didn't know xanthines are mild bronchodilators (they dilate the air passages in your lungs).  This wasn't proven until 1921, and by 1922 theophylline suppositories were used to treat asthma. The name is derived from the Greek root theo meaning tea and phyllon meaning plant.

Theophylline is an alkaloid -- a white, crystalline powder -- that was first derived from tea leaves (Camellia sinensis) in 1888.  It was first recommended as an asthma remedy by the Ancient Chinese in about 1000 B.C.  It's similar to caffeine and theobromine in its effect.

Caffeine was first isolated in 1812 and theobromine in 1841.  Caffeine is an alkaloid most commonly found in coffee beans and tea leaves, and theobromine an alkaloid from the cacao plant which is used to make cocoa and chocolate. 

All Xanthines have an effect on the central nervous system in that they, improve mental acuity, and act as mild bronchodilators and diuretics (makes you pee).  Caffeine has a stronger effect than theobromine and theophylline has a stronger effect than caffeine.

When theophylline was first discovered it was used as a diuretic for patients with heart failure to help remove excess fluid buildup (edema) in the lungs and ankles, according to Tora Navarra in her book "The Encyclopedia of Asthma and Respiratory Disorders" (New York, 2003, page 188).  In 1900 theophylline was synthesized (meaning it could now be made in a factory).

It wasn't until 1922 the bronchodilating effects of theophylline were discovered. How it causes bronchodilation is relatively a mystery, although it's believed to block the release of adenosine which causes bronchoconstriction.  It's also believed to strengthen contractility of the diaphragm to reduce fatigue, according to Navarra.  It's a respiratory stimulant.

Amimophylline was another methylxanthine discovered in 1922.  It has similar bronchodilating effects as theophylline, only it's more soluble in water and more suitable as an intravenous medication.  Aminophylline was first used in 1937.

Theophylline and aminophylline were available for use on asthmatics in the 1930s, and were basically the only effective alternative to epinephrine.  Yet use of these medicines didn't take off until the 1950s when they were approved for use on asthmatics, and by the 1970s theophylline was a top line asthma medicine.  (Again, it generally takes about 10-20 years for new ideas in medicine to catch on).

By this time theophylline was usually prescribed as a bronchodilator to control and prevent asthma at home, and aminophylline was prescribed in hospitals to be administered intravenously. If you were admitted to a hospital with asthma between 1950 and 1990, chances are you had aminophylline running in your IV at some point. 

Aminophylline was originally recommended for asthma not responsive to epinephrine, yet once Alupent and later Albuterol were discovered to be as effective as epinephrine for most asthmatics -- and safer too, aminophylline was reserved for asthmatics in the hospital who were not responding to other therapies.

Antihistamines hit the market in 1946.  This is a type of medicine that blocks the effects of histamine, which is a mediator of inflammation released during the allergic response that causes swelling and redness (inflammation) that results in the allergic response of itchy eyes and throat, stuffy and runny nose, and sneezing.

In 1947 Hydrallin hit the market.  This was a white tablet that contained both an antihistamine (25mgm of Benadryl) to treat allergies and a bronchodilator (aminophyllin 100 mcg) to relax the air passages*.  This became a popular prescription medicine for asthmatics, and later an over the counter medicine.  It was removed from the shelves in 1981.

I know from my medical records I was given aminophylline during many of my admissions for asthma. As I wrote above, theophylline was prescribed for me at an early age to help control my asthma long term.  Along with asthma, theophylline is a top line drug for chronic bronchitis and emphysema patients too.

The problem with theophylline was that it had a very narrow therapeutic level.  Too low and it didn't do anything, yet too high there were toxic effects.  Back then 20 was considered toxic, meaning the medicine might cause vomiting, ceizures and even death.  There were a few times when I became extremely nauseated and had to miss school, and in retrospect wonder if I overdosed on theophylline. 

Most side effects, though, are generally mild.  Some are similar to when you drink coffee, such as irritability, insomnia, nervousness and jitters.  Since Xanthines are also mild diuretics, it might cause you to pee more.  It can also irritate the lining of your stomach, much like drinking too much coffee could do this.

Another thing ingestion of too much xanthines can do is cause your esophageal sphincter to relax, and this may result in gastrointestinal reflux (GERD).  As we now know, GERD in itself can trigger and even cause asthma.  It's for this reason coffee is on the antireflux diet prescribed for anyone with heartburn or acid indigestion. 

Still, while there were side effects to theophylline, it was deemed to be much safer than being on systemic steroids to control asthma. It was also better than suffering from asthma.  So as with any medicine, the risks had to be weighed against the potential benefits.  For me, the benefits far outweighed the risks. 

Another problem with this drug is it only lasted in your system 4 hours, so I had to take it every 8 hours or my levels dipped in the middle of the day causing asthma symptoms.  When I was at the asthma hospital in 1985 I had a 24 hour theophylline study done, and had to have my blood drawn every few hours.  It wasn't so bad, though, because they put a line in my hand to draw from.

Greg Minton, in his book "Breathing Space: How Allergies Shape Our Lives and Landscapes," (2007, London, page 237) wrote that in the early 1980s sustained-released theophylline was introduced to the market.  By 1985 sales of this product, according to Minton, reached up to 25 percent of all prescription medicines prescribed for asthma.  Immediate and sustained release theophylline made up "50 percent of all prescriptions written for asthma drugs."


Before I was at the asthma hospital I was introduced to Slo-Dur, which is a long acting theophylline and allowed me to only take one pill a day. Yet my doctors at the asthma hospital frowned on me taking this.  Their thinking was that my levels would dip between doses, exacerbating my asthma.  So the first thing they did when I was admitted was take me off Slo-Dur and put me back on Theo-Dur.

In this way, sustained released theophylline was ahead of it's time (kind of like the Pacer).  Many established doctors refused to accept it as a top line asthma medicine.  Yet by the late 1990s sustained released asthma medicine became ideal asthma medicine because it reduced the need to remember to take your medicine at various times during the day, and this greatly improved compliance taking asthma medicines, which ultimately improved asthma control in itself.

Yet that wisdom would come later on down the history line.  At this time -- in 1985 at the asthma hospital -- I was taking 300mg of theophylline in the morning and before bed.  The results of the study showed my level dipped in the middle of the day, so my new regime had me adding a 300mg dose around 2 p.m.  This sucked because I now had to think about taking pills all day.

This medicine was one of the first bronchodilators to be released long term in the bloodstream, and this meant it only needed to be taken once or twice a day.

As you can see I had become chronically dependent on this medicine.  If I skipped a dose my lungs would itch and sputum production would increase.  I'd ultimately go into an asthma exacerbation that was not reversible with bronchodilators.  The only remedy was to get my theophylline level back up to therapeutic levels, which back then was considered to be between 15 and 20.

In 2002 my doctor at that time told me the normal dose he prescribes is 300mg twice a day.  Yet the dose I was on at that time was 600mg twice a day, and somehow that still kept me under the toxic level.  (I wonder how many cups of coffee that's equivalent to.)

In the early 1980s theophylline was determined to be "less efficacious" than anticholinergic medicines like Atropine when it comes to dilating bronchioles, yet it wasn't until the 21st century that theophylline faded away as a top line asthma drug. 

Many doctors were staunch defenders of this medicine because it worked so well for them for so many years.  I was a staunch defender of it because my body became dependent on it to the point that when I forgot to take a pill I would have the worse asthma attacks ever.

Perhaps some of my fellow asthmatics will empathise with me.  A good example of this was when I forgot to take my theophylline for three days when I was busy in college in 1988.  Absent this bronchodilator my lungs freaked out.  My chin became itchy, my chest burned, and my mucus production increased almost to the point I felt I might choke.

 My room mate Frank walked in on me and I must have been a sorry sight all frogged up on the edge of my chair, grunting with each expiration, tears in my eyes, misting nebulizer clipped between my teeth.

 "You look like you're gonna die."

"Give me ten more minutes," I grunted, "If I still look like I'm going to die, drag me to the ER."  Feeling helpless I'm sure, he stood by and watched as I suffered.

I was so familiar with these pills I could pick them out in the dark by feel

Then, right on cue, I felt the mucus letting up; the chest tickling feeling letting go, and my breath coming back.  First came a quarter breath, then a half a breath five minutes later, and finally... "Ahhhhh, man it feels good to breathe." 

All in all, it took about 30 minutes from popping that little white pill for my breathing to be back to normal.

When I was really little and this happened I'd go to the ER, but at some point in my asthmatic life I learned the difference between a regular asthma attack and one induced by a low theophyllin level.The Albuterol treatment was useless during one of these attacks, however I always took one.  "NO!" I insisted.  I had just popped a Theo-Dur pill dry.  I knew from past experience it would take about 20 minutes before my breath started coming back."NO!  I'll be fine," I grunted."Do I need to take you to the ER," he said.

That's why I was such a staunch defendant of this medicine, and was upset when Theodur was no longer made, and I had to swallow generic theophylline horse pills instead. I feared the medicine would no longer be available, and I'd die as a result. 

In December of 2007 I approached my doctor about getting off theophylin, and he said, "It's neat you bring this up, because when I started as a doctor nearly every one of my asthma patients was on theophylin, and now your one of only two."

In the past Theophylin was a top line bronchodilator usually used in conjunction with inhaled corticosteroids.  New long term bronchodilators with fewer side effects have replaced theophylin, two are called Advair and Symbicort. 

In 2005 my doctor recommended I try Advair.  In the summer of 2006 when I traveled to Detroit to visit my brother and forgot my theophylline pills I was panicked.  I thought I'd have a bad asthma attack.  Yet it didn't happen.  I think the reason is because the medicine in Advair (serevent and flovent) kept my lungs from spasming.  I did have some spasming in my lungs, but not enough to make me uncomfortable.  In fact, this may have been more psychological than actual.  Still, this made me think that it might just be possible to get off this medicine I once figured I'd be on for life. 

At my next appointment my doctor said, "You've been on theophylin so long, and it seems to work so well for you, I'd hate to tinker with it."

"One attempt, doc" I said.  "I just want to make one last attempt at getting off it.  If it doesn't work, it doesn't work."

We decided on a very, very, very, very, very slow wean.  In fact, the wean took a full year to complete.  And it worked.  On January 31, 2007, I took that last pill.  And, just in case (as if in tribute to an old friend), I left an unopened prescription bottle of theophylin in the medicine cabinet just in case. 

Once upon a time I thought I would never get off that dreaded theophyline.  Now every time I open the medicine cabinet and see that bottle of theophylin pills, I'm reminded of the importance of continued asthma research.

Today what to do with theophylline is still being debated. New evidence shows it's also an antiinflammatory and works better than leukotriene inhibitors like Singulair.  So the future of theophylline is still up in the air. Although at present it's rarely used.  I also used one of those old theophylline pills to end an asthma attack recently, so having some on hand might be a good idea too.

So while Teddy Roosevelt guzzled cups of coffee praying it would help him catch his breath, scientists gave asthmatics theophylin in the 1950s.  Now, with even greater advancements in asthma medicine, theophylin is no longer a top line asthma medicine.

(For a doctor's perspective on theophylin click here).

*Menace, Bernard A, "A Clinical Evaluation of Hydrallin and Trimeton (Tripoton) in Allergic Manifestations," Canad. M.A.J., August 1949, vol. 61, page 156. 

References:

1. Bree, Robert, "A practical inquiry into disordered respiration: distinguishing the species of convulsive asthma, their causes and indications of cure," 1810, London, page 293
2. Salter, Henry Hyde, "On Asthma: It's Pathology and Treatment," 1860, 
3. McCullough, David, "Mornings on Horseback," 2001, New York, pages 93-111

x 1955-1985: The IPPB Revolution x

"This 1960s Monaghan Ventalung ad is a part 

of our IPPB Virtual Museum.http://museum.aarc.org/gallery/ippb/,"

said an AARC Facebook post on 3/25/16

If you were a respiratory therapist anytime between 1955 and 1985 you're familiar with Intermittent Positive Pressure Breathing.  While the machines were initially introduced to be used as respirators, physicians soon decided they were useful for delivering respiratory medicine and preventing and treating post operative atelectasis and pneumonia.   The IPPB revolution was born.

The first machine capable of providing positive pressure breaths over an extended period of time without the assistance of a person was introduced in 1948 as the Monaghan Ventalung Respirator.  These machines were used during WWII as ventilators.  They were nice because the alternative was to use an Ambu-bag to keep people breathing, in which case the provider of breaths would have to rotate through two hour shifts around the clock.

It was likewise during WWII that Dr. Forrest Bird became interested  in creating a device to allow pilots to fly higher.  It was believed if a pilot could fly higher he could avoid the enemy, and stay out of range of their ammunition.  (1)

This quest lead to the first  pneumatic respirator, meaning it was completely driven by compressed air and no electricity was required.   It was a small, portable green box, and all you had to do to start it up was plug it into a 50 PSA oxygen source, such as an oxygen tank or piped in oxygen system, and turn up the flow.   It was portable and provided a nice, easy means of providing mechanical breaths. For this reason the Mark 7 became the most popular such machine, although the  Mark 1,  Bennet TV-2P Vivian, Monaghan Ventalung Respirator, and the Manley Ventilator provided viable alternatives.

It was quickly learned that when used as a ventilator there were four problems:

1. No manometers or devices to indicate how much of a tidal volume you were delivering



Bird Mark 4 (1955)

2. No alarms to indicate you were giving too much pressure or the patient was disconnected

In order to accommodate these disadvantages, respiratory therapists had to continuously check on the machines.  They would also have to be placed close to nurses stations so they could be closely monitored.  I believe this was the main reason hospitals started creating intensive or critical care units.  

It didn't take long for physicians to come up with another use for these machines.  It was believed that by providing positive pressure breaths with medicine for 5-15 minutes three to four times per day that certain condition could be treated and even prevented.  This gave birth to the use of the machines as Intermittent Positive Pressure Breathing machines, and the IPPB treatment.

The devices came with a nebulizer cup on the inspiratory circuit, and initially the medicine used was ethyl alcohol to treat patients with foaming pulmonary edema that results from heart failure.  The alcohol was nice because it soothed the bubbles, and it worked quite fast.  The IPPB was believed force the medicine deeper into the lung parychema, and thus make the medicine work better.

Soon such treatments were believed to be useful to prevent and treat postoperative atelectasis and pneumonia.  When a patient is so sore due to chest or abdominal surgery (back then it was probably usually an abdominal surgery) they tend to not want to take deep breaths due to pain.  This results in air sacks not being filled with air, and thus they collapse.  This is called atelectasis.

A non-disposable IPPB circuit with neb cup

Such hypoventilation often results in increased secretion buildup, and this causes inhaled bacteria becoming trapped in the lungs, and this results in your postoperative pneumonia.  This condition ultimately worsens the patients condition, makes treating them more complicated, and sometimes even results in respiratory failure and even death.  IPPB treatments were believed to prevent and treat this.

It was also believed IPPB treatments with Isuprel, the bronchodilator available at that time, would be useful to treat chronnic bronchitis and asthma patients.  Mucus thinners such as Alevaire and Mucomyst were also used to help patients expectorate thick secretions.  Soon these machines were used on all preoperative, postoperative and all patients with just about any respiratory disorder.  The IPPB revolution was in full stride. 

By the 1960s IPPB therapy became popular for giving aerosols to patients admitted with just about any lung ailment.  (2)  This was done despite proof it did any good. According to a 1957 article in the The American Journal of Nursing, "Nebulization Under Intermittent Positive Pressure," the following were marked as conditions treatable with this therapy: 

1.  Pulnonary edema
2. Atelectasis
3. Bronchial asthma
4. Bronchiectatsis
5. Emphysema
6. Pulmonary fibrosis
7. Silicosis
8. Impairment of respiratory function resulting from barbituate pooisoning and poliomyelitis  (3)  

Indications for such thearapy were:

1. To overcome breathing resistence
2. Provide more uniform alveolar aeration
3. Distribute aerosols to terminal bronchioles where absorption takes place
4. Relieve bronchospasm
5. Improve bronchial drainage
6. Provide exercise for respiratory muscles
7. Improve pulmonary funciton (4) 

It was difficult to get some patients to coordinate breaths with the machine breaths.  And with no way of measuring tidal volumes, it was difficult to know if you were delivering the recommended 25% greater tidal volumes than the patient's normal tidal volume.  So while the machines were simple, you had to have a good teaching technique by the RT, good coordination by the patient, and good settings dialed in by the RT.

Another thing of importance to note is that at this time respiratory therapy procedures were reimbursed by insurance companies and Medicare.  There was no incentive for administrators to question the need for such therapy considering it was profitable for the hospital.  Yet this all changed in the 1970s when such therapy came "under scrutiny" when insurance and government agents questioned that the treatments did any good, especially considering they were expensive.  (5)

It was also at this time that researchers were proving by scientific evidence IPPB treatments were no more effective than using a nebulizer to deliver medicine and an insentive spirometer to encourage the patient to take in deep breaths.  Studies also showed that IPPB therapy deposit 32% less of aerosolized medicine to the lungs than a simple aerosol treatment.  Any benefits provided from the therapy were also proven to be short lived, lasting less than an hour.   (6)

Bird Mark 7

The RT textbook, "Foundations of Respiratory Care," sums up IPPB therapy for us:  "The Overuse of IPPB was eventually to become an embarassment to the profession, but in the 1950s and 1960s, IPPB devices could be seen throughout most hospitals in the United States."  By the 1990s such devices were collecting dust in the backs of respiratory therapy closets.

Yet many smaller hospitals, including the ones I've worked for, continued to abuse this therapy throughout the 1980s and 1990.  I remember doing quite a few of them in the 1990s.  Despite evidence such therapy isn't useful, one of our physicians ordered such a treatment a few weeks ago.  I actually had to have a coworker refresh my memory on the device since it had been so long since I used one.   (7)

References:

1. Glover, 
2. Hess, Dean R., et al, "Respiratory Care:  Principles and Practice," 2012, "Intermittent Positive Pressure Breathing," chapter 18, page 370 
3. Stephen, Phyllis Jean, "Nebulization Under Intermittent Positive Pressure," The American Journal of Nursing," 1957, Sept., vol. 57, No. 9, pages 1158-1160
4. Stephen, ibid
5. Hess, Dean R., et al, "Respiratory Care:  Principles and Practice," 2012, "Intermittent Positive Pressure Breathing," chapter 18, page 370
6. Hess, ibid, page 370
7. Wyka, op cit

1950- 1980: The evolution of the artificial respiration

The technique of inserting a hollow tube through the oral cavity to the lungs was first attempted as far back as 1788, and by 1858 the equipment and procedure was improved enough for intubation to be recommended to the medical community.  The idea, however, was rejected as preposterous by all but a few physicians who dreamed that the method might some day provide a viable airway, if not given up on.

A few random physicians attempted the procedure in order to save a life, or to perform some difficult operation, yet successes were far and few between.  Yet thanks to those who dreamed of helping their fellow human beings, and who never gave up despite past failures, the procedure was slowly



By the turn of the 20th century the medical community was becoming increasingly confident in recommending and performing the procedure of intubation.  We have to realize that initially the medical community rejected the procedure altogether



1940:  Miller 

1942:  Anesthesia during intubation:  Endotracheal tubes were refined during the 19th century so by the turn of the century a variety of tubes were used, including metal and rubber tubes. Occasionally anesthetics were used to paralyze the patient prior to inserting such a tube, yet this wasn't common practice until 1942 when Harold Griffith, a Canadian anesthesiologis, used curare (succicholine).  This was a major breakthrough because it allowed surgeons the opportunity to sedate and ventilate patients during operations.  (1, page 227)



 It was also during this decade that Robert Miller refined the laryngoscope so it was straight, and it's referred to as either the Miller or straight blade.  Roger MacIntosh refined the laryngoscope so it was curved, and it's reverred to as either the MacIntosh or curved blade.  Variations of both are still used to this day, and both come with a handle with a battery that the blades attach to.  At the end of the blades are a small lightbulb so the person intubating can visualize the vocal cords.  During WWI Sir Ivan Whiteside Magill was the first to use rubber endotracheal tubes which he inserted through the nose and assisted their transfer into the airway with forceps we now refer to as Magill forceps.  In this way he also dubbed the term "blind intubation." (2)  Magill was said to have "mastered the technique of

References:  

1. Szmuk, et al, "A brief history of tracheostomy and tracheal intubation, from the Bronze Age to the Space Age," Intensive Care Medicine, 2008, 34, pages 222-228, reference to page 227
2. Subramaniam, Rajeshwari, "A primer of anesthesia," 2008, MO, Jaypee Brothers Medical Publishers

1947:  Morch's Piston Ventilator:  Dr. Ernst Tier Morch designed one of the first ventilators that provided positive pressure breaths to a patient.  It became one of the first such ventilators available in the United States and Europe.  It allowed for inhaled air to both be humidified and oxygenated, and provided an alternative respirator to the iron lung in ventilating polio victims.  It was also used during abdominal surgeries.  A second and third model would be introduced during the 1950s. (3)  It was the first modern type volume ventilator on the market. (4)  One major disadvantage is that it only allowed for controlled ventilation, which made it very difficult to ventilate patients who were awake and alert and orientated because it would be very uncomfortable.  Bucking of the vent would be quite common.  Another problem is alarms were limited. 

1948:  Continuous Positive Airway Pressure:  During WWII Alvin Barach supervised experiments whereby Continuous Positive Airway Pressure (CPAP) was used on a variety of pilots who traveled to high altitudes.  After the war he studied the use of CPAP on a variety of patients, although his work was relatively ignored until the 1980s when studies would confirm CPAP was beneficial for COPF and sleep apnea patients.  CPAP would also be studied in the 1980s as a means of preventing a patient from requiring intubation.  (v5)

1948:  Monaghan Ventalung Respirator:  It was the first machine that could be used as a ventilator and provide intermittent positive pressure breathing (IPPB).  According to Dennis W. Glover in his book, "The History of Respiratory Therapy:  Discovery and Evolution," these machines were used during WWII as ventilators.  It was also during this time IPPB therapy was first used.  The machines were introduced to hospitals in 1948.  At this time positive pressure breathing either by Ambubag or machine were provided by inserting a cuffed tracheotomy tube into the patient's airway.  A rubber mask could also be used.  Cuffed rubber ETTs were also available if necessary.

1950s-1970s:  Rubber masks:  Positive pressure breaths were often provided by using a rubber mask over the patient's mouth and nose.  One of the major complications of the rubber masks used at this time was that they were opaque and concealed aspiration or foaming pulmonary edema, and this was noted as a major disadvantage of such masks.  Another disadvantage was prolonged use caused facial skin breakdown.   Another disadvantage is air would often leak around the masks.   And yet another complication was the masks required a person to hold the mask securely on the patient's face.    When done over a prolonged period of time this could become very tiresome.  When used on polio patients nursing assistants or respiratory therapists would often work in two hour shifts.  The disadvantages of these masks could be compensated for by tracheotomies and inserting a catheter, and later  by intubation.  (v6)

1952: The Bird Mark I:  Roger Manley was an anesthesiologist who was initially concerned with ventilating patients given anesthetics.  It could be used as a ventilator and to provide IPPB.  It was often referred referred to as the Manley Ventilator.  He later refined it and re-branded it as the Mark II.

1952:  Bennett Pressure Breathing Unit:  It was studied successfuly in 1948 and marketed as the main alternative to the Bird Mark 1 by creator V. Ray Bennett.  Like the Mark I and Mark II it was a  pressure cycled ventilator.  It had a nebulizer cut for the nebulizatiion of Isuprel (a bronchodilator) and Alevaire (mucus thinner), Mucomyst (mucolytic) and ethyl alcohol (to cut allay the bubbles in foaming pulmonary edema).  The machines was commonly used as a ventilator instead of iron lungs when suctioning of the airway was required.  Iron Lungs and IPPBs being used as ventilators were pretty much phased out when volume ventilators were proven to be more effective and safer ventilators.  Bennet later refined this machine and re-branded it as the Bennett PR 1 and Bennet PR 2, both of which were still mentioned in respiratory therapy texts through the 1990 as you can see here.  (t7)

1951:  Engstrom ventilator:  Carl-Gunnar Engstrom invented a respirator that would allow "efficient control of gas volume delivered to the patient and also allows for active exhalation.  It can also be used for both adults and children, and it is the first apparatus suitable for long-term ventilation as well as for use during anesthesia."  Engstrom wrote a paper suggesting how inadequate iron lungs were and how much better volume ventilators were for long term ventilation of patients. (8)  Like the Morch Ventilator, it was among the first volume ventilators.  However, also like the Morch Ventilator, alarms were limited and the only mode was was controlled ventilation. 

1953:  AMBU Bags

While not a machine, per se, the bag valve mask (BVM) is a significant development in providing artificial breaths to patients in need. The AMBUbag invented in this year provided another less expensive option to expensive iron lungs and the recently invented and very complicated pressure respirators.  This became an important option for ventilating polio victims who presented with excessive and/or thick secretions.  BMVs were could be connected to a rubber mask for temporary ventilation, or to a tracheostomy for long-term ventilation.  Therapists worked in two hour shifts giving breaths.  You can read more about the history and significance of BVMs by clicking here. 
1955: Bird Universal Medical Respirator ( Bird Mark 7 Universal Respirator , the Bird)

Dr. Forrest Bird became interested in creating a device during WWII that would allow pilots to fly higher.  This quest lead to the first  pneumatic respirator, meaning it was completely driven by compressed air and no electricity was required.  It was a small, portable green box, and all you had to do to start it up was plug it into a 50 PSA oxygen source, such as an oxygen tank or piped in oxygen system, and turn up the flow.  Like the Mark I and Bennett respirators it was pressure cycled.  It was portable and provided a nice, easy means of providing mechanical breaths. For this reason the Mark 7 became the most popular such IPPB machine, although the  Mark 1,  Bennet TV-2P Vivian, Monaghan Ventalung Respirator, and the Manley Ventilator provided viable alternatives.

These machines had another use that ultimately became the embarrassment to the profession.  You can read more about that by clicking here.

1960:  Amsterdam Infant Ventilator Mark I:  It was one of the first ventilators available to provide IPPB to infants with respiratory distress.  In 1974 the benefits of CPAP were noted, and a screw clamp was inserted on the expiratory limb of the circuit so the device could provide both IPPB and CPAP.  It was used both in neonatal intensive care units (NICU) and operating rooms.  Calculators were used to determine tidal volume, minute ventilation, and total flow.  (QQ14)  It's generally referred to as a constant flow ventilator with a pneumatic time cycler.  The ventilator was updated as the Mark II.

1964:  Emerson Volume Ventilator:  According to Richard Branson in his 1998 article in Respiratory Care celebrating the life of John Emerson, Emerson was the second to produce a volume ventilator.  Bronson described it like this:

"This simple devise resembled a green washing machine and used a piston to deliver precise volumes. Oxygen was added into a ‘trombone-shaped’ accumulator connected to the intakeof the piston for delivery of elevated FIO2. The tidal volume was changed by a crank on the front of the machine, which controlled the stroke of the piston. Respiratory rate and inspiratory-to-expiratory-time ratio (I:E) were adjustable. The humidifier was a modified pressure cooker and was known as the Emerson Hot Pot. A belt, connected to a DC motor and pulley wheel, served to move the piston. In case of failure of the existing belt, a spare was hung inside each cabinet. The belts were similar to those used to circulate air in forced air gas furnaces in homes. On numerous occasions I have heard the story of the belt becoming loose or breaking and the spare found to be missing. Under these circumstances, the resourceful respiratory therapist would run to the parking lot and obtain the belt from a Volkswagen Beetle (the old one) and place it in the Emerson to restore it to working order. I’ve never looked to see whether the two belt sizes are compatible because it’s such a good story. In any event, the Emerson Postop VolumeVentilator was reliable and would allow ventilation of patients when other devices failed. Emerson’s device was not the first of the piston ventilators (M¨orch and Engstrom preceded him), but it was the first device to allow independent control of I:E." (15z)

1964:  Bourn's Piston Driven Infant Ventilator (LS104-150)

This was the first ventilator specifically made for infants.  It was a volume ventilator, which meant that while it may have save lives, it also may have been responsible for forcing too much air into little lungs and causing collapsed lungs which further hampered physician's attempts to save sick neonates.  IMV ventilators and CPAP were later proven to be more effective and safer for use on neonates.

1967:  The Puritan Bennett MA1

In 1940 Ray Bennet produced a gas delivery system that involved a "jewled pneumatic valve - the 'valve that breathes with the patient."  It was this concept that allowed the Puritan Bennett company to create the the MA1. (a16) (b17)

The ventilator gave care practitioners much more control over the patient's breathing.  One reason is  the machine offered more than one mode instead of just control.  Along with control modes it offered assist control (AC), which allowed the patient to trigger spontaneous mechanical breaths between scheduled machine breaths.  Later on Intermittent Mandatory Ventilation (IMV) was added via an external line,  and later Synchronized Intermittent Mandatory Ventilations (SIMV).  IMV and SIMV allowed the patient to take spontaneous breaths between machine breaths and made it much more comfortable for the patient.

It was a compact and durable unit that could easily be carted to the patient's bedside, and provided the patient with positive pressure breaths once connected to an endotracheal tube (ETT) that had to be inserted into the patient's airway.  This device and others like it (volume ventilators) took over for the above mentioned IPPB machines as the main sources for mechanical breathing.  Because the patient was intubated, gaining access to the patient was much easier for nurses and doctors, and airway maintenance was much more efficient.  For it's time, the MA1 was a very good and durable ventilator.

The basic settings were simply dialed into the machine: rate, tidal volume, sigh depth, sigh rate, etc.
While it was a bit complicated, the ventilator could be connected with many different alarms and manomoters, such as high rate, low rate, high pressure, low pressure, and tidal volume and rate.  However, these could be quite complex to set up and operate.

Many hospitals had one.  In fact, when I started as an in 1995 the hospital I worked for had one as the "emergency back up" ventilator.  All the knobs were on the front and it was pretty easy to set up, it was just a challenge to operate all the alarms.  Thankfully the device was shipped to somewhere in Asia prior to the turn of the century.  Ultimately there was an MA2, yet it wasn't anything as popular as the old faithful MA1.

1967:  PEEP:  Ashbaugh and Petty were the fist to describe a condition called Acute Respiratory Distress Syndrome (ARDS), and they described it as a severe respiratory distress associated with refractory hypoxemia, or hypoxemia (low oxygen in the blood) that does not get better with increased oxygen, and decreased lung compliance and diffuse lung infiltrates.  The disease condition causing the syndrome may vary from patient to patient, including sepsis, pneumonia, trauma, etc.  In 1971 the condition was renamed adult respiratory distress syndrome to differentiate it with the neonatal form.  It's often referred to as noncardiogenic pulmonary edema.  There was a high rate of morbidity (as high as 100 percent) with the syndrome, and the initial treatment they found effective and eventually recommended was increasing Positive End Inspiratory Pressure (PEEP).  A valve was inserted at the end of the expiratory circuit.  Since this time various treatments have been recommended, such as low tital volumes (6-10cc/kg/ideal body weight) with positive results. (yyyyyyy)

1970:  Respirator name change

I'm probably no alone in wondering why sometimes these machines are referred to as respirators and now they seem to be more commonly called ventilators.  The actual reason may continue to elude us. However, Glover describes in his great book on the history of respiratory therapy that sometime around 1970 the term respirator was changed to ventilator.  As a rule of thumb, I think we can safely conclude that most breathing machines made prior to 1970 were referred to as respirators, and most breathing machines made after 1970 are referred to as ventilators.  Perhaps only the Lord knows why the change in name was made, or even if it was an official name change.

1969:  Baby Bird

By the 1960s there were a series of ventilators that provided breaths for adults, yet few that would do the same for infants.  A major concern was that providing pressure into an infant's lungs would cause a pneumothorax.  Up to this point the main method of ventilating newborns was with neonatal Ambu-bags, although there were occurrences where a gentle squeeze of the bag may turn to a harsh squeeze and a collapsed lung.  So the market was open for a baby ventilator to deliver consistent breaths.  Forrest Bird tapped into this market with the first ventilator specifically designed for ventilating infants.  It was time cycled and pressure limited, and provided constant breaths at a desired frequency.  It was crude by today's standards, and required some math to set up and maintain, yet it was a good ventilator for its day.  This and other similar ventilators helped to significantly reduce infant mortality rates by up to 70 percent by the end of the decade

1971:  Servo 900 Ventilator

It was small, slightly larger than two shoe boxes, and all the knobs were on the front.  It became known as a minute ventilation ventilator because the respiratory therapist would set the minute ventilation and the tidal volume and respiratory rate would be secondary.  In this way, in volume control mode the tidal volume could be set.  This machine had a sensor to make sure the tidal volume was adjusted with changes in patient compliance so the patient was guaranteed to get the set tidal volume.  This was the first ventilator to have this function.

In order to set tidal volume, though, you had to do a little math.  I know because when I did my clinical rotation in 1996 at Blodgett Hospital in Grand Rapids Michigan they still used this ventilator on a regular basis.  It was also commonly used on cardiac patients at Mott's Children's Hospital at the University of Michigan when I did a rotation there.  Many students were afraid to use it, yet once you were used to it it was a very nice ventilator.  However, students were thankful when it was ultimately replaced by the Servo 300 Ventilator.

It was the first ventilator to have all the alarms you needed right on the machine, and it was also the first ventilator to allow for the addition of a device so you could see pressure and flow curves.  This was nice because you could see what you were doing and make changes based on the needs of the patient. (d18)

 It was also the first ventilator to provide both volume control and intermittent positive ventilation (IMV), which was later improved to synchronized intermittent positive ventilation.  These new modes improved the physician's ability to wean a patient from the ventilator. (e19)

The ability to measure exhaled CO2 was a feature added in 1978, which provided clinicians a noninvasive means of measuring CO2 other than by obtaining an invasive arterial blood gas (ABG). The inline CO2 monitoring was nice because it allowed clinicians to quickly adjust to changes in the patient's condition rather than wait up to 30 minutes for the results of an ABG to be returned.  (e20)

In 1981 Positive End Airway Pressure was introduced to the Servo 900 series.  There were other methods of adding PEEP prior to electronic PEEP, yet they were much more complicated and provided non-measurable and unstable levels with increased expiratory resistance.

Eventually pressure support (PS) added, making the Servo 900 C the first ventilator that interacted with the patient and supported his breaths. Before PS was an option all modes of ventilation provided mandatory breaths.  Pressure control was also added to the Sero 900 C.  (e21)

1973:  Intermittent Mandatory Ventilation:  (22xxxxx)  The concept that a patient be able to take a spontaneous breath between mechanical breaths only made sense.  It was believed if this was possible it would prevent the patient from bucking the ventilator, giving the patient more control.  Other initial claims were that it would reduce the need for sedation, improve kidney and heart function by lowering intrathoracic pressure, facilitate weaning from the ventilator.  Initially the IMV set up was complex and required intensive effort by the patient.  With this new mode, engineers concentrated on finding better methods of allowing the patient trigger breaths.

1976:  Bourne BP 200 respirator

It was another in a line of neonatal ventilators.  Like the Baby Bird, it was set up using crude mathematical formulas.  Steven Sittig, RRT, described it best in his article, "Neonatal Mechanical Ventilation Support:"

"Few clinicians today would remember an early model Bourne BP 200.  To set the To set a respiratory rate on this model, the clinician had to set the inspiratory time and then calculate the inspiratory-to-expiratory-time ratio (I-E) for the desired rate.Then the RT had to move theI-E ratio knob to the approximate ratio, watching to avoid a red light on the display that signaled an inverse I-E ratio. Finally, the clinician had to check the ventilator rate using a watch.   (23)

I personally don't remember this ventilator, but my first job as an RT had a Baby Bird as the back up ventilator, and even after I was instructed on how, I prayed I never had to use it:  it was very intimidating.  Just the idea of using a calculator and watch to set up a ventilator seemed so old fashioned.  After looking at that vent I was happy for new technology.

Sechrist Infant Ventilator

Early 1970s:  Sechrist infant IV 100B:  A pneumatically powered, single circuit, O2 blender, continuous gas flow,

1976:  Bourns Electric Adult Respirator (a.k.a. the Bear 1)

It was a hugely vertical rectangular blue ventilator with simple control knobs on the front interface.  The ventilator was updated twice during the 1980s as the Bear 2 and Bear 3.  A Bear Cub was also marketed for the infant market to replace the previous Bourn infant respirators on the market and compete with newer IMV infant electric ventilators.  Several other Bear products have since been introduced to the market, including the Bear 33 in the 1990s, the Bear 1000 Adult/ Pediatric Ventilator in 1992, and the Bear Cub 750 VS Ventilator in 1996.

1978:  Stylets:  The idea of using a stylet inside an ETT to assist with intubation was first used in 1978.  The first stylets were central venous catheters, yet later stylets were manufactured specifically for modern disposable PVC plastic ETTs, of which come in a variety of sizes.

1980:  Synchronized Intermittent Mandatory Ventilation:  This was basically an improved version of IMV that allowed the ventilator to better "synchronize" the spontaneous and the mechanical breaths to make being on a ventilator more comfortable for an awake patient, and to prevent the patient from "bucking" or "fighting" the ventilator.  The lower the respiratory rate the more spontaneous breaths the patient was allowed.  The mode also required ventilators to be more sensitive to recognizing the patients desire to take spontaneous breaths.  (24xxxx)

References:  (under construction)

1. Szmuk, et al, "A brief history of tracheostomy and tracheal intubation, from the Bronze Age to the Space Age," Intensive Care Medicine, 2008, 34, pages 222-228, reference to page 227
2. Szmuk, ibid
3. The Wood Library Museum, "Mueller-Morch Piston Respirator," woodlibrarymuseum.org, http://woodlibrarymuseum.org/museum/item/64/mueller-morch-piston-respirator-, accessed March 2, 2012. 
4. Kishen, Roop, chapter 2, "Perceptions, Perspectives and Progress:  Intensive Care 50 years on," of the text, "Critical Care Update 2010," 2011,  page 7, edited by Roop and Vineet Nayyar
5. Wyka, Kenneth A., Paul J. Mathews, William F. Clark, ed., "Fundamentals of Respiratory Care," 2002, . page 630, Section IV, Essential Therapeutics
6. Wyka, ibid
7. Sills, J.R.,  "Modifying IPPB Therapy," Respiratory Care Certification Guide, 1994, second edition, St. Lois, Mosby.
8. Gedeon, Andras, "Science and Technology in Medicine," 2006, page 450-51, Carl-Gunner Engstrom
9. ippbHess, Dean R., et al, "Respiratory Care:  Principles and Practice," 2012, "Intermittent Positive Pressure Breathing," chapter 18, page 370
10. ippbStephen, Phyllis Jean, "Nebulization Under Intermittent Positive Pressure," The American Journal of Nursing," 1957, Sept., vol. 57, No. 9, pages 1158-1160
11. ippbStephen, ibid
12. ippbHess, Dean R., et al, "Respiratory Care:  Principles and Practice," 2012, "Intermittent Positive Pressure Breathing," chapter 18, page 370
13. ippbWyka, op cit
14. QQ  Holand, J. et al, "Historical Note:  Keuskamp and Amsterdam Infant Ventilator," Anesthesia, 2006, 1, pages 65-71
15. Branson, Richard,  Branson, Richard D, "Jack Emerson:  Notes on his life and contributions to Respiratory Care," Respiratory Care, July 1998, vol. 43, no. 7, pages 567-71
16. "Company History," Puritan Bennett Corporation,  http://www.fundinguniverse.com/company-histories/PuritanBennett-Corporation-Company-History.html, accessed February 27, 2012
17. "About us:  Respiratory Products for nearly a century," PuritanBennet.com,  http://www.puritanbennett.com/about/index.aspx, accessed February 27, 2012
18. "About us:  History of Ventilation," maquet.com,  http://www.maquet.com/sectionPage.aspx?m1=112599762812&m2=112599885558&m3=112600545105&m4=112806653448&wsectionID=112806653448&languageID=4, accessed February 27, 2012
19. "The Servo Story:  Thirty Years of Thechnological Innovation Evolving with Clinical Development of Ventilatory Treatment Strategies," www.maquet.com,  http://www.maquet.com/content/Documents/Site_Specific/MAQUETcom/GENERAL_The_Servo_Story.pdf, accessed February 27, 2012
20. "The Servo Story...," ibid
21. Sittig, Steven E, "Neonatal Mechanical Ventilation Support," AARC Times, April, 1999, page 51
22. xxxxxxSmith, B.E., C.D. Hanning, "Advances in Respiratory Support," British Journal of Anesthesia, 1986, 58, pages 1380150 

xxxxxx Smith, B.E., C.D. Hanning, "Advances in Respiratory Support," British Journal of Anesthesia, 1986, 58, pages 1380150

yyyyyyyyy Klein, J.J., et al, "Pulmonary function after recovery from the adult respiratory distress syndrome," Chest, 1976, 69, pages 350-55

1854: M. Priory fine tunes stethoscope and percussion

Pierre Adolph Priory (1794-1879)

Joseph Auenbrugger, Jean Corvisart, and Rene Laennec introduced the medical community to the technique of chest percussion, and the invention of the stethoscope to improve the technique of auscultation.  Both techniques became valuable for helping physicians diagnose diseases of the chest, although both needed to be perfected.  

By the time of his death in 1826, Rene Laennec saw his invention of the stethoscope become accepted by his peers.  However, he would readily admit that his new tool was not yet perfected. He would spend many hours himself improving upon it, and when he died this task was left to his peers.

Pierre Adolph Piorry (or M. Priory, with the M. coming from his French name) was born in 1794, served in the Napoleanic wars in Spain, and served at the Atarazanas Hospital in Spain where he was able to witness military surgery." In 1814 he returned to his medical practice in France, and, like Laennec, served as a student of Corvisart. He qualified as a physician in 1816, the same year Laennec invented his stethoscope.  (1, page 675)

This is a picture of the Priory binaural stethoscope complete with
the pleximeter(round, solid ivory disks on bottom second from left)
and fingerthimble ivory percussor (on botton right).  Picture from 1828.
Photo from http://www.antiquemed.com/binaural_stethoscope.htm

He had a gift as a teacher, and between 1817 and 1826 he delivered lectures on physiology and pathology.  In 1826 he was appointed physician to the Paris Hospital.  In 1837, after many years of attempting to do so, he became professor of medicine at Paris School of Medicine (l'Hospital de la Pitie, Paris).  He was 43.  (1, page 676)

He then took off where Laennec left off, working hard to fine tune the binaural stethoscope.  The product he ended up with would be the general design of most stethoscopes used for the rest of the 19th century.  He also worked to improve the technique of percussion.  His work in this area created excitement for the remainder of the century, it would ultimately be for naught. (1, page 675)

A Classic Reprint Series of Priory's book
is proof his ideas are still sought after.
The first edition was published in 1826.

His stethoscope was trumpet shaped and made of wood, although it was shorter and thinner than Laennec's.  It came with a removable wood plug, ivory earpiece and chest piece, with the chest piece also serving as a pleximeter (described below).  This design was also much more pleasing to physicians, and was much easier to carry in their bags. (5)

In a 1979 Biography of Priory, Alex Sakula said of Priory

Priory, enthused by Laennec's invention, developed an ambition to emulate the great master and to achieve fame in some similar fashion. Priory describes in his poem Dieu L'ame et Nature how he came to study percussion.  He prayed to God asking to be able to make some discovery like that of Laennec.  A few months later, he had slight pruritus and while scratching the skin over his chest he heard a sound.  He interposed a coin and scraped it and obtained a stronger sound, which varied according to the density and elasticity of the underlying organ." (1, page 577)

This is a picture of Priory's Pleximeter. (5, page 311)

Sakula said that the next day he began his work on percussion, and hoped that what Laennec had done for auscultation he could do for percussion.  On February 28, 1826, he read "read a prize winning paper on his new method of percussion to the Academie Royale de Medecine.  Laennec (then very near his death) was one of those present." (1, page 577)

Scott Alison, in his 1861 book, "The physical examination of the

 chest," described the procedure of percussion as follows: 

 The pleximeter is to be placed in or over an intercostal space,

 or upon a flat surface, and fitted well with gentle pressure upon

 the body,and held by the thumb and forefinger of the left hand. 

It may be employed together with a hammer or with the fingers." 

A percussion hammer is sown here.  (5, page 311

In the paper, Sakula said, he described his new technique of doing percussion, which involved placing a small plate between the patient's skin and the percussing finger.  He called the plate a pleximeter from the Greek w``ords to strike and to measure. (1, page 577)

As Laennec experimented with various materials while trying to perfect his stethoscope, Priory experimented with various materials while trying to perfect his pleximeter, said Priory, "but finally settled on a small ivory plate, 5 cm in diameter.  He also devised a combined stethoscope and pleximeter made of ivory and cedar wood." (1, page 577)

This little gadget shows the extent that some physicians went to 

create the perfect pleximeter.  Scott Alison described it as:

"An instrument combining both a pleximeter and a hammer 

was contrived by Dr. Aldis some years ago. It consistsof a

 hammer moving on a fulcrum, and of a disc of cork which 

receives the blow of the hammer. The cork disc is placed 

upon the chest, and the hammer is raised by the finger to the

 required height. The higher the hammer is raised, the more force

 is obtained. The hammer falls by the operation of a spring.

 Great uniformity of blow is obtained by this instrument. 

This ingenious contrivance has obtained the name of 

echometer." (5, page 312)

After all the publicity that that stethoscope had garnished since Laennec introduced it in 1819, percussion had lost some of its luster.  Some probably believed the stethoscope would replace it completely.  (1, pages 576-577)

However, Sakula said:

"Piorry did not regard percussion as competing with auscultation, and taught that the two techniques were supplementary one to another." (1, page 577)

These are a few of the varieties of wooden binaural stethoscopes
in use by physicians as of 1861. (5, page 316)

There were still many physicians who did not adapt his stethoscope and pleximeter.  Many who finally accepted his research on percussion came up with their own techniques for performing the procedure.  For instance, the preferred method became the use of the finger of one hand used as the pleximeter, and the finger of the other hand as the percussor.  Yet the principle is the same.  (1, page 577)

This is a flexible stethoscope.  In his 1861 book, Scott Alison said,
"In employing the flexible stethoscope, it is even more necessary
than in the case of the wooden instrument to observe that the object
end is well applied so as to close the tube.  If left partially open,
scarcely any sound is perceived. (5, page 321)

The Cyclopaedia of Practical medicine, edited in part by John Forbes, best concludes the accomplishments of Priory regarding percussion: (3, page 7)

M. Priory, a young Parisian physician, has the honor of having, if not invented, at least brought into a formal and matured shape, this new application of the discovery of Auenbrugger, and with practical results greater precision and importance than could have been anticipated. (3, page 7)

Dr. Sibson's pleximeter 

consists of a plate of 

ivory which receives

the blow, and of a brass

hammer or weight

working in a metal frame.

. The weight or hammer

is raised by the fingers;

these being removed, 

the weight or hammer 

falls upon the ivory plate

by the elasticity of an

indiarubber band connecting 

the weight or hammer 

with the ivory plate.

The hammer works

perpendicularly

to the plate. (5, page 313

Like many new tools invented or discovered to assist physicians do their jobs better, the Priory stethoscope and pleximeter were not accepted by all physicians.

Piorry remained a famous physician until his retirement at the age of 72 in 1866.  He died at age 85 in 1879.

Most stethoscopes used for the remainder of the 19th century after Piorry's death were based on his design, designed by various physicians, produced by various manufacturers, made of various materials, and scattered throughout various publications. Some of these other binaural stethoscopes were made by Quain, Stokes, Arnold, Barclay, Elliotson, Dobell, Loomis, Burrow, Clark, Camman, and Furguson. (4, page 626)

Yet long before he passed from this world his hard work paid off.  By 1854 percussion had been fine tuned so that it was often performed not just over the chest, but over various organs of the body to help doctors diagnose any pathological disorders.

And his stethoscope remained the most popular one used for the remainder of the 19th century.  There were many similar versions by various manufacturers, although most of them are simply adaptations of the binaural stethoscope that M. Priory fine tuned.

References:  

1. Sakula, Alex., "Pierre Adolphe Piorry (1794-1879): pioneer of percussion and pleximetry," October, 1979, Thorax ( 34(5): 575–581).  
2. "The Binaural Stethoscope," antiquemed.com, http://www.antiquemed.com/binaural_stethoscope.htm, information reviewed March 8, 2012
3. Forbes, John, Alexander Weedie, Conolly, editors, "The cyclopaedia of practical medicine," volume 1, London, 1833
4. Camman, Donald M, "Historical Sketch: Stethoscopes," A Reference Handbook for Medical Sciences, edited by Albert Henry Buck, by various writers, volume VI, 1888, New York, William Wood and Company, 626-628
5. Alison, Somerville Scott, "The physical examination of the chest in pulmonary consumption and its intercurrent diseases," 1861, London, John Churchill