Friday, April 28, 2017

1917: Meltzer's pharyngeal Insufflation Apparatus

Along with being the first to link asthma with allergies, Dr. Samuel James Meltzer (1851-1920) invented a mechanical device that could be used to provide artificial respiration.

He was born in Russia, studied medicine in Germany, received his medical degree there in 1882, and emigrated to New York in 1883 where he set up a medical practice. In 1904 he became head of the Rockefeller Institute's Department of Physiology and Pharmacology, and in 1907 he became a full time physiologist. He became the original president of the American Association of Thoracic Surgery in 1918.

So in his quest to improve knowledge of medicine, and to improve the technology for helping people, he was well prepared.

One of the neat things about the formation of the Humane Society in 1774 was that the organization kept data of all the cases it's members participated in. So this data, along with the data of many other societies, was studied by Dr. Meltzer. He likewise had access to medical studies, many performed by others, some performed by himself.

Upon reviewing the data, he set out to invent a device to provide artificial breaths that was both safe and effective.  He referred to his final product in a 1917 article in Medical Record as the Pharyngeal Insufflation Apparatus.  It was a device that was operated by a foot bellows.  When the foot bellows were depressed by the operator, air flowed through a hard, kink free rubber tubing and into the lungs of the victim.  When the operator took his foot off the bellows the patient exhaled by natural recoil of the chest wall.  

It actually was a rather simple device, but operating it took quite a bit of training and practice, mainly due to the fact that much coordination was needed.  Before I explain how the device was operated, first I must explain the parts.  

Fig 2 -- This shows an enlarged pharyngeal tube (Ph .T.) with its various
particulars,and a stomach tube (S.T.) in it
1.  Foot operated bellows:  As noted previously, when depressed by the foot air flows through the tubing.  

2.  Tubing:  It has to be of a hard rubber that was kink free

3.  Oxygen tank:  Now this part is optional.  Oxygen tanks at this time were large and bulky, and were only available in certain locations, mainly hospitals.  The rubber tubing was connected to metal adapters and the oxygen tank was introduced to the system.  As air flowed over this connection, oxygen would be drawn into this flow.  

4.  Reservoir bag:  Next in line was a large rubber bag.  During exhalation air (or oxygen) accumulated in this bag so that as soon as inspiration was triggered the air was ready to give the victim a "full respiratory blast." 

5.  Respiratory Valve:  After the reservoir bag as a valve. A ring on this valve would be moved left to give a breath and right to cause exhalation.  

6.  T-Tube:  This "carries on its rubber end a clamp screw, which, when not screwed down, permits most of the air to escape through the tube, while, on the other hand, by gradually screwing down the clamp upon the rubber tube the amount of air entering the pharyngeal tube will gradually increase." In other words, this clamp was Meltzer's way of studies that showed that bellows force too much air into the lungs too fast, thus causing trauma to the lungs.  The T-Tube allowed the operator to control this pressure, thus, ideally, preventing pulmonary trauma. 

Fig 3 - Showing an earlier arrangement of the
apparatus. B., bellows: T.T. T-Tube inserted
between the bellows and the respiratory valves:
R.V., respiratory valve: Ph. T., pharyngeal
tube: S.T., stomach tube.
7.  Pharyngeal Tube:  This was a tube, usually connected right to the system, that was inserted into the patient's mouth and into the trachea.  It was Meltzer's version of an endotracheal tube (what Meltzer referred to as an intratracheal tube, although he noted the other term was catching favor).  His tube was described by himself like this: 
This tube has a flat surface at its lower side which rests on the tongue and a curved surface on its upper side. At the pharyngeal end of the tube the upper surface is longer than the lower one. The external end of the tube has a protrusion with a neck for connection with the respiratory valve and an opening through which a stomach tube may be pushed down through the esophagus into the stomach. When no tube is in use this opening is closed with a movable plate. (See Fig. 2.)... furthermore, the prolongation of the curved side of the tube raises the soft palate and thus prevents the escape of air through the nose.
If this tube was not available, a trach tube may be used, or a mask.  However, Meltzer noted that a mask should not be used except for in the case of an emergency because it's use increases the risk of driving "infectious materials usually present in the nose and pharynx directly into the lungs and thus produce fatal inflammation of that organ.  By using a pharyngeal tube that risk is reduced to a minimum."

The problem with the tube was that "the introduction of the tube into the trachea requires some dexterity and practice."

8.  Stomach tube:  This fits into the external opening of the pharyngeal tube and is meant to prevent air from entering the stomach and intestines.

9.  Tongue Forceps:  These are used to move the tongue out of the way prior to insertion of the pharyngeal tube

10.  Tape:  This is used to secure the pharyngeal tube to the tongue.  This serves two purposes:  One, to prevent the tongue from blocking the airway; two, to secure the pharyngeal tube and stomach tube into place.

11.  Paddle Wooden Board:  This is strapped using belts and meant to compress the stomach.  The idea here is to help prevent the entrance of air into the stomach and intestines. 

12.  Handy Small Bag:  All the parts of the apparatus, along with the tongue forceps, scissors and tape, "ought to be kept connected and kept in readiness in a handy small bag."  This will assure that they are readily available when they are needed.  

Once he had put together the device of his liking, he put it to the test on animals and dead human beings.  Of interest is that he admits that when he started testing the device he was not aware that previous studies showed that the use of bellows increased the risk of harm being done to the lungs, and air getting into the stomach, "which does more harm than good."

Fig 4 - Showing the apparatus in position. except the bellows
and the oxygen tank. You can also see in this picture the correct
application of the paddle wooden board.  Here you can see that
it is fastened around the belly by the use belts.
Although by performing his tests he came to this realization on his own, and, based on his findings, made several changes to the design of his apparatus.  One such change was the addition of the t-tube, which allows for pressure to be gradually increased so as not to over distend the lungs.  It was also based on his studies that he came up with the idea of the stomach tube and the paddle wooden board.

Meltzer describes his plan for using his apparatus on a victim in need:  You can decide for yourself if he makes it look easy or complicated: 
When coming to a victim who requires immediate artificial respiration the order of the procedure should be as follows: First the application of the abdominal board—in order to prevent the entrance of the insufflated air into the stomach and the intestines. Second, to pull out the tongue as far as possible by means of the forceps. Third, to insert the pharyngeal tube of the readily connected apparatus as deep into the pharynx as possible with the fiat side of the tube on the tongue. The tongue should now be tied to the tube by means of tape— not too tight... The working of the bellows with one foot, and the moving of the ring of the respiratory valve with the thumb of the right hand should be started immediately on tying The tongue to the pharyngeal tube. At the beginning of the procedure the T-tube should be kept open; it should soon be gradually screwed down until the thorax shows a distinct raising when turning the ring to the right and falling, when turning to the left. The heaving of the chest need not be too strong.The degree of the heaving can be readily controlled by means of the screw, which should be turned down gradually, and which will then be capable of accomplishing all the care which may be obtained from the use of a mercurial valve. Moving of the ring thirteen to fifteen times per minute will give a satisfactory respiration; or the operator may time the moving of the thumb by therhythm of his own respirations. In case of need one individual who had some training may accomplish all three procedures and start the artificial respiration in less than one minute after finding the victim.
He notes that it may take some practice to get the timing to get the rhythm down of moving the ring and pressing the bellows.  He recommends going with the rhythm of your own breathing.

Samuel James Meltzer (1851-1920)
He also recommends that any potential rescuer should be trained in the methods of manual respiration, and of the two most common methods at this time -- the Schaefer and the Sylvester-- he recommends the Schaefer method.  To learn more about the manual methods of respiration, click here.

Meltzer also notes that if the operator is concerned with the circulation of the heart, the Schaefer method may be performed by a second rescuer.  If there is no second rescuer, Schaefer suggests an idea that that once occurred to Schafer:
"If he were now confronted with the task of resuscitation he would kneel astride over the subject and perform the simple motions of horseback riding without employing his hands and arms at all." This simple manner of employing the prone method could be readily combined with the use of the author's pharyngeal insufflation apparatus, and the operator who is performing the Schafer method could at the same time manipulate with one hand the respiratory valve and with the other hand regulate, when necessary, the T-tube. But the operator must learn tomove the ring of the valve to the left (expiration) synchronously with throwing his body downward upon the individual and to move his thumb tothe right (inspiration) simultaneously with the raising of his body from the individual.
The most interesting aspect of this apparatus was that it was not patented, so the "cost is probably less than one-fifth of the patented apparatuses."

  1. Meltzer, S. J., "History and analysis of the methods of resuscitation," Medical Record: A Weekly Journal of Medicine and Surgery, July 7, 1917, Volume 92, Number 1; Thomas L. Stedman, editor, Medical Record, Volume 92, July 17, 1917 - December 29, 1917, New York, William Wood and Compay

Wednesday, April 26, 2017

1912-2001: Dr. Martin Wright

If you were a respiratory therapist during the 1960s, 70, 80s and even the 1990s, you probably heard of the name: Wright. You may not know a first name, or even the person, but you were familiar with his products: the Wright Respirometer and the Wright Peak Flow Meter.

And even while his products have made their way to the dark side of shelves in the back of supply rooms, or simply faded into oblivion, his product line has been refined and re-introduced into the market by other names, or padded into other products, with their users having little knowledge of where they came from, nor who introduced them to the marketplace for us to use.  

His name is Basil Martin Wright.  He was a bio-engineer who had a flare for inventing things that measured inspiratory and expiratory flow.  The need for such devices developed during the 1950s when improved anesthetics and pain relievers allowed physicians to perform routine surgeries, particularly abdominal surgeries.  

Wright Respirometer
The need developed for a machine that would breathe for patients.  This was one of the main reasons for the invention of the positive pressure ventilators as you can see here.  On these old ventilators there needed to be some mechanism for measuring the volumes of inspiration and expiration, or tidal volumes, of patients.  This is where the Wright Spirometer comes into play.  

Although this is not how Wright came to invent his devices.  In 1949 he joined the Medical Research Council's for pneumoconiosis, a lung disease caused by inhaling mineral dust.  He realized the unit "lacked the mechanisms of monitoring and studying lung capacity of patients.  So it was for this council that, in 1959, he invented the Wright Peak Flow Meter, the first device for measuring peak expiratory flow (PEF).  This made studies of lung function possible and lead to a greater understanding of lung disease." (1, page 11)

Case for Wrights Spirometer
Such devices also allow the physician to assess the progress of the patient over time.  As the patient gets better, the PEF will get higher, and if the patient gets sicker the PEF may become lower.  The first peak flow meters were large and cumbersome, but in 1974 Wright invented a simpler, cheaper, portable device that could easily be used by the patient at home as a tool to monitor the progress of his disease.  I wrote about the history of the peak flow meter in this post  (1, page 11)

Today peak flow meters are made by a variety of manufacturers, are for single patient use, and are easy to use.  Most asthma experts recommend all asthmatics have one at home, and they blow into it every day at the same time, and to write down their highest number.  This number is referred to as the patient's personal best.  Then the patient makes some simple calculations, and as the PEF starts to drop to a certain point, a plan can be devises what to do and whether the doctor should be called, or whether to simply get to the emergency room, or call 911.  I wrote about the peak flow meter in this post.  

Basil Martin Wright 
In 1957 he started working for the National Institute for Medical Research in London, focusing on creating a similar device to allow anesthesiologists to monitor the tital volumes of patients under the power of anesthetics and pain relievers.  This was important because such medicine has the power to knock out the respiratory drive, and measuring tidal volumes is a great way to measure loss of drive to breath.  

The devices were used to help the anesthesiologist know if prolonged assistance with breathing was indicated, or if the patient required assistance with breathing by use of a mechanical ventilator.  The device was ultimately used by respiratory therapists to monitor the tidal volumes on patients with neuromuscular disorders, or to monitor the progress or regression of patients on mechanical ventilation.  We used to use the Wrights Respirometer daily as part of our weaning screen.  Today the measurements are made by the microprocessor on the ventilator.  

  1. World Almanac Library, "Cutting Edge Medicine:  Machines in Medicine," 2007, Arcturus Publishing Limited, page 11

Monday, April 24, 2017

1910-1920: The oxygen revolution

Joseph Barcroft (1872-1947)
In 1886 he received his M.D. from Cambridge,
and began his study of hemoglobin.
He exposed himself to different environments
to determine their effects on the human body.
Three significant events occurred at the dawn of the 20th century that resulted in increased interest in supplemental oxygen therapy. The first was the invention of a means of measuring oxygen saturation. The second was an experiment that Dr. Joseph Barcroft performed on himself. The third were experiments by WWI physicians to find a treatment for pulmonary edema caused by gas poisoning.

The ability to draw arterial blood was a significant discovery. It was hurter in 1912 who introduced the method. (2, page 693)

Yet even more significant was the machine blood could be inserted into that would determine the how saturated hemoglobin molecules in the blood were with oxygen molecules. This is referred to as oxygen saturation. Once inserted into the machine, the saturation was reported as a percentage.

John Scott Haldane (1850-1936)
He graduated from Edinburgh University in 1884,
and worked with his uncle at Oxford,
where he became interested in air,
its composition, and effects on humans.
Adolf Fick of Germany and Paul Bert of France described oxygen tensions as units of partial pressure, and it was these units that made it possible to describe the difference between arterial and venous blood. Since the partial pressure of oxygen in arterial blood is higher than the partial pressure of oxygen in venous blood. Or at least this is the case in a healthy individual. (1, page 4) (2) (6)

Donald Dexter Van Slyke (1883-1971) and John Scott Haldane (1892-1964) of Scotland developed effective means of measuring these differences. (1, page 94) (2) (6)

Further studies by various experts determined the normal levels and critical levels of oxygenation. It was determined that a normal arterial saturation of hemoglobin is between 95 and 98 percent, and a normal venous saturation is between 70 and 75 percent. These new values allowed physicians to monitor a patient's oxygenation status, and the effectiveness of oxygenation therapy. (2)(3, page 369)

Among the first to prove the significance of this discovery was Sir Joseph Barcroft, who lived for six days in an atmosphere that had 18 percent oxygen in the air, as opposed to the normal 21 percent that's in roomair. Alvin L. Barach, a pioneer in oxygen therapy, liked to use Barcroft's experiment as an example to prove the significance of oxygenation.

Barach explained:
"On the last day, the oxygen saturation of his arterial blood was 88 per cent., and after the performance of work 83.8 per cent. He lay in the chamber racked with headache, with occasional vomiting, and at times able to see clearly only as an effort of concentration. He became faint on exertion. His pulse, normally 56, had risen to 86. These effects were apparently due purely to oxygen want. The degree of anoxemia that produced them has frequently been found in pneumonia and heart disease by the investigators mentioned above. In many instances, the saturation of the arterial blood falls to far lower levels. It would, therefore, seem likely that lack of oxygen in the degree often found in disease would produce bodily discomfort, disturbances in function and damage to living structure." (3, page 369)
The effects on Barcroft were similar to the effects of pneumonia and heart failure for some patients. Studies showed that the oxygen saturation could range from 75-95 percent in cases of cardiac insufficiency, and 60-95 percent in cases of pneumonia. (2, page 693)

So it became apparent these diseases, as they progress, decrease the amount of oxygen that gets to the blood and to hemoglobin.  

Various studies, including the Barcroft study, proved that a low level of oxygen stimulates the central nervous system to stimulate various changes within the body in an attempt to return oxygenation back to normal: heart rate increases, respiratory rate increases in rate but decreases in depth, patient may become delirious and may have hallucinations  If not treated, death may result.  (2, page 694)

So these studies proved to the medical community the significance of observing the signs and symptoms of poor oxygenation and speedily treating them with oxygen. (2, page 694)

Oxygen was not meant to cure, but to treat the symptom of low oxygenation long enough to allow the physician to remedy the underlying condition, which may include: (2, page 694)
  • Pneumonia
  • Acute Cardiac Failure
  • Severe Hemorrhage
  • Epidemic Encephalitis
  • Ascent to high altitudes
  • Complications of chronic cardiac insufficiency
  • Pulmonary Edema
  • Acute Bronchitis
  • Carbon Monoxide Poisoning
  • Nitrous Oxide Poisoning
  • Other anesthesia
Further studies also allowed physicians the opportunity to determine that a therapeutic percent of oxygen for most diseases was between 40 and 60 percent, and it's for this reason the oxygen chamber, oxygen catheter, and nasal cannula generally are not effective for oxygenating patients with severe oxygen deprivation. (2, page 696)

Studies likewise showed greater than 70 percent could cause pneumonia, and did so in rabbits. (3, page 373)

It was probably based on these and similar studies that John Haldane, another pioneer of oxygen therapy, would recommend 41% oxygen administration continuously for patients suffering from anoxemia (Haldane would coin a new term to describe this: hypoxemia). (6) (7) (8)

In fact, it is said Haldane once mused:
Intermittent oxygen therapy is like bringing a drowning man to the surface of the water—occasionally. (7) (8)
Yet even while he and other physicians proved the usefulness of continuous oxygen therapy during WWI, it would take a few more years for it to catch on. (6)
Oxygen mask designed by Haldane in 1917

A third significant event was the gas poisonings that occurred during WWI. Phosgene was used by the enemy on the war front because, when it combines with water in the lungs, it creates hydrochloric acid, which damages lung tissue. If inhaled in high enough doses it may cause pulmonary edema within 6-10 hours, leading to acute respiratory distress syndrome (ARDS).  As the illness progresses, the lungs lose their ability to pass oxygen to pulmonary capillaries, therefore causing anoxemia or hypoxemia. (6)

While oxygen was not thought to cure these patients, it was believed that it would treat the symptoms caused by anoxemia, particularly cyanosis and dyspnea.

Sometimes patients who presented with pulmonary edema due to gas poisoning were treated in oxygen chambers, which could be supplied with 40-60 percent oxygen. These chambers were found to be effective in treating cases of chronic gas poisoning. Some patients would spend up to 16 hours a day inside one with good results. (3, page 360)

However, this therapy wasn't practical for common use.

Another means of providing these patients oxygen was to use a tube or funnel to aim the oxygen at their faces, although studies showed this provided no more than a 2 percent increase in oxygenation of inspired air.

So this opened the door for an improved oxygenation apparatus that was easily portable by medics, comfortable to wear, could be used long term for chronic cases, and provided a therapeutic dose of oxygen. John Haldane invented such a device, and it was called the "Haldane Apparatus." (3, page 370)

Alvin Barach said Haldane's apparatus provided oxygen blended into the air the patient inspired, and by doing this the amount of oxygen making it to the alveoli was greatly increased. By this means, the patient was supplied with a therapeutic level of oxygen. (3, page 370)

Barach described the device as consisting of an oxygen tank, a reducing valve, and a face mask. He said:  (3, page 370)
"The mask was connected with a connecting bag which received oxygen from the tank, and with the outside air, from which the patient breathed. Oxygen was added to the inspired air in amounts of from one to four liters per minute. This was largely used in acute cases with generally good results." (3, page 370)
The problem with the Haldane apparatus was the only patients who tolerated it were those who were comatose. It worked great for these patients. Yet for others, for those who were awake and alert, it was not comfortable. Patient's complained that having the mask over their faces created a feeling of claustrophobia, and the mask was also hot and stuffy. This was especially a problem on hot days. Some patients simply didn't tolerate the mask, and some even ripped it off, refusing to wear it. (3, page 370)

Another problem, a pretty severe one actually, was it was impossible for clinicians to see through the opaque rubber masks. Clinicians learned to be vigilant, although this sometimes didn't prevent them from getting busy and not recognizing a patient was vomiting or expectorating foaming pulmonary edema. When not recognized, secretions occluded airways resulting in worsening anoxemia.

This concern opened the door for a more comfortable and safer oxygenation device.

One such device was the nasal cannula or prongs devised by Captain Adrian Stokes, M.D., in 1917. Stokes created the device while triaging patients on the war front who were suffocating due to pulmonary edema, and to which the tight fitting rubber mask of Dr. Haldane was not feasible. The metal cannula provided less oxygen than Haldane's device, although it helped medics keep pulmonary fluid from re-entering and blocking the airway. (1, page 38) (3, page 370)  (5, page 8) (6)

Stoke's cannula was a device similar in design to what we use today, although it was supplied by rubber tubing and the prongs were made of metal, and therefore was not very comfortable. However, patients tolerated it much better than the rubber mask, and of course it was safer. (1, page 38) (3, page 370)  (5, page 8) (6)

A similar device was the rubber nasal catheter, which was initially invented by Arbuthnot Lane in 1907, although re-introduced by Stokes in 1917. The catheter was introduced into the United States in 1931 by Waters and Wineland.  (1, page 17) (5, pages 8-9) (7, page 20)

The soft, rubber catheter (later made of pliable plastic) was a 12 inch long tube that was blindly inserted into one of the nostrils and then secured to the forehead. The patient would then open his mouth, depress his tongue to the bottom of his mouth, and the physician or nurse would check to see that the catheter was in place at the back of the airway. (4)

The end that remained outside the patient had a fitting to which oxygen supply tubing was connected.  On the distal side of the catheter, the side inside the patient's airway, were a series of small holes to allow oxygen to enter the patient's airway.  (4)

Catheters were designed for adults and pediatrics, the flow was set at 1- 5 lpm, and the the delivered oxygen was 22-35%.  The catheters would stay in the nose for a day or two.  If it was needed longer a new catheter had to be inserted. (4)

Most experts recommended changing the catheter every 24 hours to prevent tissue breakdown, and most hospital protocols eventually called for changing it every eight hours.

So you can see that while it was more convenient for the patient, there was some risk to the patient too.  It also provided some inconvenience for those taking care of patients requiring it.

While nasal catheters were simple to insert and manage, and while they were generally well accepted by patients, they did not provide enough oxygen in patients presenting with acute pulmonary edema or worsening pneumonia to eliminate cyanosis.  (3, page 370)

The nasal catheter was the most commonly used device for supplying supplemental oxygen prior to the invention of the modern nasal cannula in the 1960s.

Figure 2 --Apparatus for giving oxygen.(3, page 374)
Another option was a device similar to the one in figure 2.  The apparatus works this way: 
"The patient breathes through the rubber mouthpiece M (or a mask could be used) through the can of soda-lime C into a rebreathing bag B. The carbon dioxide exhaled is removed by the soda-lime, and oxygen is admitted from the tank O at a sufficient rate to keep B inflated.In this way the patient rebreathes pure oxygenfrom the apparatus,but since his nose is left open he dilutes this with a certain proportion of atmospheric air. In practice this results in the inhalation of from 40 to 60 per cent, oxygen." (3, page 374)
Yet another option was the oxygen tent. These were clear canopies that were made to cover the entire bed. A machine at the bedside provided an environment inside the tent of about 30 percent oxygen. These were effective as far as oxygenating some patients, although the original oxygen tents were hot and stuffy, and this particularly posed a problem on hot days.

Patients would generally go inside one long enough to catch their breath, and then they'd return to breathing room air. (1, page 94)

Barach recommended to physicians that the best means of measuring oxygenation status was by monitoring the heart rate, respiratory rate, and especially the level of cyanosis (bluish skin color). This was much more logical than an invasive blood draw. (3, page 370)

Caregivers would ultimately learn to monitor these signs, along with level of consciousness, before, during and after therapy.  This, they found, was the best means of monitoring the effectiveness of oxygenation therapy, and whether or not it was still needed.  (2)

What equipment to use to supply oxygen depended on what equipment was available, the physician taking care of the patient, and the independent oxygenation requirements of patient.

How long oxygen therapy was used primarily depended on the patient and how quickly, or slowly, the underlying condition resolved. (2)

Still, by 1922, when Barach wrote many of his papers, he explained that...
"the use of oxygen in medical therapy occupies at present an uncertain role." 
Despite Barach's doubts, the 1920s was an oxygen revolution of sorts.

Barach would go on to study the effects of oxygen therapy on a variety of respiratory diseases, including pneumonia and cor pulmonale. He would also study the effects of oxygen therapy on respiratory failure. For his work, he is often considered the father of modern oxygen therapy.

  1. Glover, Dennis, "History of Respiratory therapy," 2010, Indiana, page 94.
  2. Barach, Alvin L., "The Therapeutic Use of Oxygen," The Journal of the American Medical Association, Vol 79, No. 9, Chicago, October 26, 1922, page 693-699
  3. Barach, Alvin L, Margaret Woodwell, "Studies in oxygen therapy with determinations of blood gases," Archives of Internal Medicine, Vol. 28, 1921, Chicago, American Medical Association, pages 367-393
  4. Hess, Dean,  Neil MacIntyre, Shelley Misha,"Respiratory Care:  Principles and Practice," page 281
  5. Wyka, Kenneth A.,  Paul Joseph Mathews, William F. Clark, editors, "Fundamentals of Respiratory Care," 2002
  6. Grainge, CP, "Breath of Life: the evolution of oxygen therapy," Journal of the Royal Society of Medicine, October, 2004, 97 (10), pages 489-493
  7. Heffner, JE, "The story of oxygen," Respiratory Care, January, 2013, volume 58, number 1, pages 18-30
  8. Sekhar, KC., "John Haldane: The Father of Oxygen Therapy," Indian Journal of Anesthesia, May-June, 2014, 58 (3), pages 350-352

Friday, April 21, 2017

1910: Early PEP and Insentive Spirometers

Cohen's Resistance Valve (Figure 38)
Physicians near the middle  of the 19th century were aware of the importance of exercising your respiratory muscles to prevent and treat lung disease.  By 1910 the concept of taking deep breaths was used as a means of preventing and treating consumption.

From the 1850s onward various devices were created to exercise the lungs by inhaling and or exhaling against resistance. Some of the more common methods were described by Tissier in his 1903 book "Pneumotherapy: Including Aertherapy and Inhalation methods."

According to Tissier, all of these devices or techniques provide similar results, and none has an advantage over the others.  The ultimate goal being to exercise the lungs on a daily basis with the goal of, over time, increasing respiratory capacity.  

Some examples are:

1  Valsalva Meneuver:  This is a technique we still recommend today when a patient's heart goes into certain funky rhythms to try to get it back to normal. Back then it was used as a therapy to exercise the lungs.

Basically, the patient takes a full inspiration, and then exhales through a closed glottis with all your respiratory muscles, making a full, and forceful expiratory effort. When I explain this to my patients, I basically say to the patient to exhale as though you were trying to take a crap. It's a funky way of explaining it, but it works.

The effect of this technique (and all the devices described here) is to exercise all the respiratory muscles, and it also increased intra-thoracic pressure. By increasing intrathoracic pressure, the circulation is also slowed because the vessels are squeezed and this slows circulation.

Figure 40 -- Howe's Breathing Tube
The increased pressure also recruits alveoli and portions of the lung not used regularly, and this works to improve breathing.  This creates more room for air exchange in the lungs.  We now know this causes a form of PEEP that increases oxygenation.  A similar effect is created when a newborn is grunting or crying.  Thus, Tissier suggests crying exercises respiratory muscles, and parents who don't let their children cry risk having their child's lung muscles not developing properly, and this predisposes them, so he believed, to tuberculosis of the lungs.

Figure 41-- Resistance Spirometer
2.  Ramadge Tube:  The tube was recommended for patients suffering from tuberculosis. Due to his invention he is often described as the Father of Aerotherapy.

Tissier describes the Ramadge Tubes this way: "Ramadge had his patients breathe the emanations from heated tar through long narrow tubes, the diameters varying with the ages of the patients, and attributed all the benefits derived from the inhalation to this respiratory exercise of the lungs. The length of the tube serves the double purpose of protecting the patient's face from the heat of the inhaling apparatus, and of retarding the free egress of air from the lungs, which is an essential feature of a perfect inhaler." I describe the Ramadge Tube in more detail in this post.

Figure 42-- Spirometer used for resistance Exercises
3.  Dobell's Residual Air Pump:  I described this device in my last post. A patient placed the mask on his face and exhaled against pressure. The results are similar to the effects of the valsalva maneuver. However, I think the next device more resembles our modern devices, and appears to be much simpler.

4.  Cohen's Resistance Valves:  Pressure results from "Little cylinders containing ebonite valves controlled by spiral springs (Fig. 38). The tension of the spring is regulated by turning the cap of the cylinder, and a scale on the outside indicates indicates the pressure used. This device allows for resistance against both inspiration and expiration.

5.  Cohen's Simplified Resistance Valve:  It's similar to Cohen's Resistance Valve. It's less expensive, but it's also less accurate. Along with causing resistance, the "inhalant chamber (A) contains a sponge or tuft of absorbent cotton, which may be saturated with some medicinal substance." (See figure 39)

6.  Howe's Breathing Tube It's similar to a Ramadge Tube, which is why the tubes are sometimes referred to as either Howe's or Ramadge's Tube. Since it provided pressure and also allowed for the inhalation of medicine, both the Ramadge and Howe tubes are sometimes referred to as inhalers. (see figure 40)

7.  Resistance Spirometer:  They are used the same way as the Ramadge and Howe Tubes, or any of the above devices and, again, offer no advantage over any of the above. However, the device can be used day to day and allows the patient to monitor his progress by writing down daily the values indicated on the spirometer. There were many similar devices, two of which are indicated in figures 41 and 42.

Further Reading
  1. The first PEP Therapy, Incentive Spirometer
  1. Tissier,Paul Lewis Alexandre, edited by Solomon Solis Cohen, "Pneumotherapy: Including Aerotherapy and inhalation methods," volume X, 1903, Philadelphia, P. Blakiston's Sons and Co., pages 227-230.  If the profession of respiratory therapy existed in their era, we would be reading their books.  However, as it was, their books were written for the medical profession.  For a more detailed description of any of the devices mentioned on this blog click on the links provided. Unless otherwise indicated, all material from this post was from Tissier's book. 
  2. Minnesota State Medical Society, "Transaction of the Minnesota State Medical Society," 1886, St. Paul, H. M. Smyth Printing Co.

1908: The Bratt's Resuscitator

The Bratt's Resuscitator was among the equipment available during the first 20 or so years of the 20th century to assist with artificial resuscitation.  The device would have been purchased by various gas, mining and electric companies to be used when a person was exposed to gases or was electrocuted.  The devices were also found useful for other purposes, such as attempts to revive victims of drowning. 

The pictures below were provided in a 1908 edition of the The Canadian Mining Journal.  The top two pictures show a rescue station at a mining company.  The following is the description of the mining station:
Among the equipment of the station is a "Dr. Bratt" resusitator. This is a device for inducing artificial respiration and administering oxygen. It consists of a flash of oxygen connected by the tube with a mask for the mouth and nostrils. By moving a handle to and fro the lungs of an unconscious person may be inflated and deflated as in natural breathing. The deviceis of special value for reviving men who have been "gassed," particularly those suffering from the carbon monoxide poisoning" 
The photo in the lower left shows the apparatus by itself.  The photo in the lower right shows it in use.  A Draeger apparatus (the pulmotor) was noted as among the equipment available at the station. Another part of this rescue station was set up as an emergency station, replete with beds, blankets, etc. (1 page 594-596)  

  1. Gray, F. W., "The mining operations of the Dominion Coal Company," The Canadian Mining Journal, November 15, 1908, Volume XXIX, Number 22, Toronto; Published in the "Index: Canadian Mining Journal, volume 29, January 1, 1908, to December 31, 1908, The Mines Publishing Company Limited, Toronto, Ontario. Click the links for a better view of pictures. 

Wednesday, April 19, 2017

1907: The first mechanical ventilator: The Pulmotor

Medics using Pulmotor to save a lifeIn 1907
Concerned for the people who were becoming asphyxiated and dying due to gas exposure in mines, Heinrich Drager of Germany (1898-1986) set out to invent a machine that would help keep these people alive until the gas wore off.  In 1907 he finished his work, and received a patent for what he referred to as the Pulmonator.  (1, page 8, 12)

The device was connected to an oxygen tank and was then powered by oxygen pressure and alternated positive and negative pressure to provide breaths.  It was the first time cycled ventilator*, in that it gave a breath for a designated amount of time, guaranteeing the patient would get an equal breath with each inspiration.  (1, pages 12,14)

This is the title and pictures of an article about how the Pulmotor
"pulled back through the doors of death" 400 persons in Baltimore
"during the past six years."  Left:  A police officer in a "special vehicle,"
ready "for a dash to save a life."  Right: "Showing how the Pulmotor is
used to save a life."  The article notes: "In a large number of cases,
 a small machine, one that could be lugged around by a grown man,
 was responsible for this almost miraculous feat in life-saving. 
It was a pulmotor, the property of the Consolidated Gas, Electric Light 
and Power Company." Published in Gas Age, circa 1922. (7, page 258)
A later model was designed by Bernard Drager (son of Heinrich) and Hans Schroder that was pressure cycled, in that it gave a breath until a designated pressure was met, guaranteeing the patient's lungs would not be over-inflated. This later model turned out to be much more efficient for clinical use because it (at least in principle) was supposed to prevent over-inflation of the lungs, and was easier to use by clinicians. (1, page 18)

The operator would also have to have knowledge of pressure controls and of pressurized oxygen. He would set up the machine, turn on the tank, and place a rubber mask over the mouth and nose of the victim.  In order to provide adequate ventilation, he would have to hold the mask tightly over the patient's face.  As you might expect, this would have been daunting work.

"No one can foretell the need of a Pulmotor. To put too much dependence
 on being able to borrow a 
Pulmotor is dangerous. The owner may be using it,
or someone else may have it. To depend entirely on manual methods,
or on devices of questionable merit is leaving yourself open
 to your own reproaches  and to those of others. Pulmotors are the standard
 resuscitation apparatus throughout the world. In their ten years of service to humanity
 not one case can be found where injury resulted from their use.
 On the contrary, they have saved countless lives, many after all other means,
 both mechanical and manual, had failed." (10, page 156)
He'd also have to have an assistant watch the oxygen tank to make sure it was full and change it when it was close to becoming empty.  Yet since there were no efficient regulators at this time, the operators would have to use a formula to determine how long a tank would work, or they would simply guess.  

The machine worked similar to fireside bellows  in that it forced oxygen into the lungs, and then it sucked air back out.  (2)  It was mass produced by Draegerwerks, a company in Ludwig, Germany, and advertised heavily in various magazines marketed to gas companies, such as Gas Age.  

A 1922 article in Gas Age shows a special police automobile specially prepared with a Pulmotor owned by the Consolidated Gas, Electric Light and Power Company.  The product was originally purchased   in 1913 for "employees of the gas company overcome by gas in trenches or underground passages. Then some one outside the company was overcome by gas and the pulmotor crew was asked to lend its aid.  That was the beginning, and... requests for use of the life saving apparatus 'just grew' until now the private calls run up into the hundreds each year." (7, page 257)

sent rushing in a special automobile through the streets of the city day or night at any minute to try and add another name to the list of those whose lives it has saved."  (7, page 257)
"Your Fire Department Needs it... Our Health Department Needs it:
Do you know... that the pulmotor has saved lives of those
who have been pronounced dead by reputable physicians?"
chimes an advertisement in The American City (circa 1915)
for The Draeger Oygen Apparatus, a.k.a. the pulmotor.
This and similar ads could be seen in various magazines marketed
to cities around the U.S. and Europe.  (11)
So, as you can see, the product, or apparatus, was put to good use, and was soon donated to the Baltimore Police Department.  Volunteers, in their "special automobile" could be "

There was but one pulmotor for all the three-quarter of a million inhabitants of Baltimore, (7, page 257) and this was pretty much how it was in most cities with the privilege of having such an apparatus.  Since there were few of the products available, it often took a while getting to the scene.  In such cases, as noted in the Gas Age article, "time, and not the machine, may have been responsible for the death... in the 187 deaths recorded by the company, nearly all were what are called hopeless cases.  In other words, the pulmotor was called after death and probably ensued for hours, principally in cases of suicide by inhaling gas, and drownings."  (7, page 257)
Typical mask used for pulmotor and similar devices.  It was designed
by Dr. John Haldane to be worn by people exposed to gas during WWI.
The Haldane Mask in this picture was was a redesigned model so that
it could be used "in either foul or fresh air."  Oxygen came from the tank
through the oxygen inlet (A).  A one way valve in the jount box (B)
opened on inspiration allowing air (or oxygen) to come from the tank,
and closed on expiration to allow expiration into the atmosphere.
 (13, part III, page 25)

The article describes the typical rescue attempt for the crew:  (7, pages 257-258) 
There is little reward for the small band of 20 men who go out with the pulmotor on calls.  A telephone message is received from the police that "John Jones"  at a street in the farthest end of the town has been "found in a gas filled room." The lifesaving machine rushes out and John is revived. In a newspaper account of the affair it may be casually mentioned that "the pulmotor was called," but that is all. Nothing is said of how long the crew worked to resuscitate John. Perhaps it took four hours. Four or five tanks of oxygen may have been used. But it is all in a day's work for the pulmotor crew. To report another person as "saved" is all the reward they ask... Most calls the pulmotor answers are to revive persons who attempt suicide by inhaling gas. Answering these is not a necessary part of the work of the gas company, as its responsibility ends at the gas meter, but it responds just the same. Others are overcome by an accidentally turned on gas cock, and again sometimes the pulmotor is called out to revive whole families overcome by coal gas or some one overcome while tinkering with his automobile engine... Then there are the calls from hospitals when some one has failed to revive after an operation. The machine is also wanted at times for cases of heart trouble, at child birth, in attacks of pneumonia and other ills, and one case is on record where a few years back the pulmotor kept a baby with diphtheria alive for several days... Most reports of the operating of the pulmotor, telling of suicides or unsuccessful attempts to end one's life, are gruesome. But every now and then there is a report that brings a smile.(7, page 257)
The top two pictures show a rescue station at a mining company.
"Among the equipment of the station is a "Dr. Bratt" resusitator.
 This is a device for inducing artificial respiration and administering 

It consists of a flash of oxygen connected by the tube with a mask
 for the mouth and nostrils. By moving a handle to and fro th
e lungs
of an unconscious person may be inflated and deflated as in natural breathing.
 The device
is of special value for reviving men who have been "gassed,"
 particularly those suffering from the carbon monoxide poisoning"
The lower left shows the apparatus, and the lower right shows it in use.
A Draeger apparatus (the pulmotor) was also among the equipment.

Part of the rescue station is set up as an emergency hospital.
(14, page 594-596)  Click link for better view of pictures.
I find it interesting that this mechanical ventilator was at times rushed to the hospital.  Little did they know that the machine they were using was just the beginning, and that within the next 50 years mechanical ventilators would be common in hospitals, although used to save lives just the same.

So most pulmotors were advertised and purchased by places where people were at high risk, such gas companies, mining companies, and electric companies.  As success stories were shared by the media, such companies donated the use of their pulmotor to the community.  As calls came, the team rushed to treat victims of electrocutions, near drownings, medicine overdoses, smoke inhalations, gas inhalations, drug overdoses, poliomyelitis, etc.

Each city had their own system set up, as some gas, electric and mining companies created their own teams to rush the pulmotor to the victim, while other cities stored the pulmotor in emergency vehicles, such as police cruisers, or stored them in the hospital setting.

Another example of the pulmotor team helping the community can be seen in a 1912 editorial in the South Carolina Practitioner:
The Los Angeles Police Commission has accepted the offer of the Los Angeles Gas and Electric Corporation for the free use of the Pulmonator.  The machine will be kept at the receiving hospital.  A pulmonator was recently successfully used in San Diego on a case of morphine poisoning that had remained unconscious overnight.  (4, page 412)
Yet another example can be seen in a 1913 issue of Electric Review:  (9, page 69)
"In order to make available over the largest possible territory the use of its free pulmotor service, The Toronto Electric Light Company, Limited, has secured the co-operation of Captain Ward, in command of the Government Life-saving Station at Ward's Island, and Mait Aykroyd, the well-known lifesaver at the foot of York Street... "Many persons apparently drowned have been revived by the pulmotor when all other means of resuscitation have failed. A large number of the company's men has been trained in the use of the pulmotor by The Toronto Electric Light Company, Limited and two or more are always on duty at the company's station at the foot of Scott Street. The telephone call for Scott Street is Adelaide 404...  "The police and the public are urged to call for the pulmotor immediately and not try to do without it. The pulmotor is perfectly capable of resuscitating drowned persons if life is not extinct, but it cannot restore life. The quicker it is put to work, the better is the chance of saving life... "The rapidity with which the pulmotor may be obtained was illustrated only the other day. A drowning accident occurred at Centre Island and some one telephoned to Captain Ward. He at once started for the Scott Street Station of The Toronto Electric Light Company Limited, in his fast motorboat, while one of his crew at the life-saving station telephoned to Scott Street that he was on the way and to have the pulmotor with its crew ready to meet him. In three minutes Captain Ward was at the Scott Street dock, had picked up the pulmotor and the company's men, and was on his way to Center Island, which was reached in nine minutes... "It has also "been arranged to send the pulmotor in a automobile to meet Captain Ward where time can be saved in so doing... "The public and police are urged to report drownings immediately to Captain Ward or Mait Aykroyd. They will give the requisite orders to the pulmotor crew at Scott Street and assume command of the situation in person". (9, page 69)
In the event that a person truly stopped breathing yet was still technically alive, the machines must have been a Godsend, as they would have provided an opportunity for bystanders to help keep someone alive. This resulted in an evident media hype, where rescue attempts with the Pulmotor were reported by the Press. One such example was provided by the January 13, 1913, issue of the Pipeline and Gas Journal:
"The first (Consolidated Gas Company) now has four of these devices in use, and the first practical trial of its was made November 7, 1912, when a call for the crew with the apparatus came in from the Flower Hospital, to which institution a woman had been carried.  She was suffering from gas asphyxiation... The emergency crew... responded to the call.  The patient was seemingly not breathing and the pulse could not even be detected.  (The foreman) attempted to show the doctors how to operate the apparatus, but they were slow to comprehend the actual method, wherupon (the foreman) assumed the task himself.  In about 10 mintues the patient was restored to consciousness." (6, page 34)
A report published in 1922 by the United States Bureau of Mines, "Report of the Committee on Resuscitation from Mine Gases," suggested that despite various success stories using the machine, the benefits of using it may have been over-hyped by Draeger and the various gas, mining and electric companies who owned one as public relations stunts. The media just sort of naively played along.  (8 page?)

For instance, the Bureau report listed some of the few actual success and failure stories written about in the various medical literature (such as the Journal of the American Medical Association), and said  that "in none of these instances is there a careful account of the action of the instrument. And only when an observer publishes his experience in detail, gathered in a number of cases, can we judge whether his observations are unbiased, his statements truthful, and his conclusions justifiable." (emphasis added)

The report continued:  
By the kindness of the head physician to the Edison Co., of New York, opportunity was obtained to examine 21 records of gas poisoning in which the pulmotor was reported as having been used with success. Most of the reports were written by chauffeurs and only a few by physicians. In most of the reports no distinction was made between unconsciousness and absence of respiration; and, as already explained, the sensitiveness of the higher centers of the brain to lack of oxygen may result in unconsciousness, while the centers governing respiration still continue active. Indeed, breathing may persist for some time after the degree of asphyxia is such that death is almost certain to ensue. Only in a few of these 21 cases was there reason to assume that breathing might have been suspended. Letters sent to the various physicians mentioned brought either an unsatisfactory answer or none at all. Of two additional cases that were reported, in one no machine was used, and in the other, a case of opium poisoning, intratracheal insufflation was employed and erroneously regarded as identical with the action of the pulmotor." (8page 20)
The report notes that in many of the reported success stories, there was more evidence that something other than the pulmotor revived the victum, such as:  (8, page 21)
  • Oxygen provided by the device (8, page 21, 23)
  • Hypodermic injection (of some unknown medicine) 
  • Manual respiration (such as prone position or the Sylvester method 
  • Manual respiration coupled with oxygen 
  • Unknown what was done because nothing was written, other than that the pulmotor was at the scene  
  • Breathing not absent, and pulmotor not even indicated (8, page 21-23))
There were cases where the victim was pulled from the scene, and nothing was written about what happened  in the interim prior to the pulmotor arriving on the scene: 
In the eighth case (Burgess) the pulmotor was first applied 30 minutes after the victim had been removed from the gas atmosphere. No statement is made as to what was done for him in the interim. In the ninth case (Enzian) Dr. McGuire, of Wilkes-Barre, " endeavored for two hours to revive her by artificial respiration. Failing in this, a pulmotor was brought a distance of 8 miles, and under the manipulation of Mr. G. T. Holdaman the patient was revived in two or three hours.'' .Cases 8 and 9, in which the victims lived a long time before the application of the pulmotor (half an hour and two hours), do not present convincing evidence. In case 7 the pulmotor did at least as much as the Silvester method, but that does not show that it did more. These reports are in no manner satisfactory documents for demonstrating the superiority of the pulmotor as a device for artificial respiration.  (8, page 22)
In one case described by the bureau, "manual artificial respiration combined with oxygen continued the respiratory function for much longer than the critical period, and the pulmotor was not necessary." (8, page 21)

In other words, according the the Bureau, in most cases there was no evidence the pulmotor provided any benefit whatsoever to the patient.  The only people who benefited were those who profited from sales of the machine, and those who profited by the positive public relations from the service provided. (8, page 23)

Or, as stated in the report: 
"In regard to such reports it is scarcely necessary to point out that, because of the financial interests involved, a considerable degree of caution should be exercised in estimating their valueA high official of one of the important electric companies in the country testified to a member of the committee, "We have to buy these machines, even if they are no good, as an evidence of our good faith and our desire to do everything possible to safeguard the public and employees."
  " (8, page 23)
This suspicion may have been hinted at in an editor's note attached to the above mentioned article from Gas age(7, page 257)
Hint to gas men.  Have you a pulmotor at the plant?  Offer it to the police department and by and by some newspaper reporter will write it up. (7, page 257)
It was also hinted at in the article noted above from Electric Review, which began with this:
In line with its policy of establishing friendly relations with the public, as well as to perform a worthy public service, the Toronto Electric Light Company has announced through local papers that it desires citizens of Toronto to call for the company's pulmotor in drowning accidents. (9, page 69)
We must note here, however, that there were obvious success stories, and even the Bureau noted this: (8, page 23)
Although the cases reported above do not furnish convincing proof of the necessity or the exceptional value of the mechanism of the pulmotor, that mechanism is probably capable of creditable performances, and in some instances may have favored the restoration of normal breathing. (8, page 23)
The medical profession is historically known to regard new products with suspicion.  It is not uncommon for something new, like the pulmotor, to be criticised, and in some cases criticised heavily.  Yet in the case of the pulmotor, I might have to presume the criticism was probably justified. 

Surely some criticism was simply slathered about by stubborn old professors and physicians who were stuck in their ways and resistant to any change.  In other cases the evidence might have been used to prop up another product, such as the Dinker Respirator (the first marketable iron lung, or negative pressure ventilator)

In 1929, Drinker, along with Charles F. McKhann, published in the Journal of the American Medical Association, "The Use of a New Apparatus for the Prolonged Administration of Artificial Respiration: A Fatal Case of Poliomyelitis," evidence that manual resuscitators did not provide the necessary oxygen needed to benefit patients, and mechanical resuscitators like the pulmotor** forced too much air into the lungs too fast, increasing the risk  of doing more harm than good.  (5)(12)

Dinker and McKhann were, however, right.

There were three basic concerns regarding the pulmotor, all of which were the subject of various reports.

1.  Too much air forced into the lungs too fast may cause over-inflation.  Concerns regarding over-inflation of the lungs began in 1829 when Leroy d'Etiolles used fireside bellows to breathe for dogs, and he later noted that such efforts were harmful to dogs, sometimes killing them.   Studies by S.J. Meltzer and others confirmed the concerns of d'Etiolles by showing the lungs of animals inflated with the pulmotor for extended periods of time "presented an uneven appearance -- small collapsed areas alternating with emphysematous ones."  (15, page 2, 5)  Such studies showed that the Pulmotor had no way of sensing if it was giving too much or too little air.  In other words, it did not compensate for airway obstruction that may occur in lungs with diseases such as asthma, bronchitis, etc. Likewise, if the patient was awake this would result in uncomfortable breathing.  Adjustments were made to the machine over time to accommodate for this problem, such as a switch that allowed the operator to end inspiration. The switch from time-cycled to pressure cycled was also an effort to remedy this problem.  Modern clinicians continue to be concerned about over-inflation.  (5)(1, page 24)(12)(13)

2.  Negative pressure may cause atelectasis.  The negative pressure (suction) intended to suck air out of the lungs was thought to cause collapsed lungs, or atelectasis.  This was assumed to be a problem due to the results of an autopsy that found atelectasis in the lungs of a patient the Pulmotor was used on.  ()  This concern is no longer considered relevant. (1, page 24)(13)

3.  Delay in set-up time may harm cause harm to patient.  In many of the stories reported by the media, there were delays as long as an hour, or even more.  This may have been due to delays in realizing there was a problem, and also due to delays in rushing to get the machine and to set it up.  One can only imagine the stress of the situation that may have resulted in those unfamiliar with the equipment fumbling to set it up, and then to keep it running.  Delayed efforts to set up the device may result in patient asphyxia. (5)

4.  Clinician exhaustion may cause harm to patient. The mask had to be held on to the patient's face, and it often had to be held firmly in order to provide adequate breaths.  This in itself would have been exhausting.  Yet the clinicians would also have suffered from mental fatigue and stress in order to make sure their equipment was running correctly, and that there was still oxygen in the tank.  (5)

5.  Air is "liable to be driven into the stomach, but this can be prevented by pressure on the trachea." (8, page)  This was just one more thing operators of the device had to be aware of.

6.  Not enough oxygen was delivered to the patient:  According to studies performed by John Haldane and Yandell Henderson, the Pulmotor delivered only 26.75% oxygen to the patient, as compared with the 21% oxygen contained in room air. This would not be sufficient supplemental oxygen to provide much benefit to the patient. (16, page 5)

A report originally published in 1920 by the Great Britain Department of Scientific and Industrial Advisory council noted the following:
We have tried all these devices (mechanical respirators*); in addition to the drawbacks of complexity, bulk and weight, those producing forced breathing are physiologically unsound, and their use is not free from serious danger. Forcibly to blow oxygen into lungs which are already distended to the full, or to apply strong suction to lungs already deflated, is to risk permanent injury to those organs. Again, though one tries to reduce the possibility by drawing the tongue well forward, there is a chance of these apparatus functioning upon the stomach instead of on the lungs. We therefore consider that all forms of forced-breathing revivers should be abandoned, and that the simple form, in conjunction with artificial respiration, should be employed solely.  (13, part III, page 25)
Regardless of the concerns, by 1908 there were 3,000 Pulmotors in use at various locations around the United States and Europe.  By 1918 that number doubled to 6,000, and by 1956 there were 12,000 Pulmotors in use. (1, page 24)  By this time, however, the machine had been improved upon many times to make up for past flaws.

While the Pulmotor may not have been the ideal ventilator, it was a great idea that was put to good use.  The product was ultimately phased out with the invention of the bag mask valve (AMBU-bag) and better mechanical ventilators in the 1950s.

*  Time cycled means that inspiration ends when flow from the mechanical ventilator ends and expiration begins.

**Note:  There are other devices that were similar to the pulmotor and were used as "revivers at mine rescue stations, such as the Bratt's Apparatus and the Lungmotor.  However, these devices were hand operated as opposed to mechanically operated.  There were also simpler methods, mostly which consisted of "an oxygen cylinder, a reducing valve, a throttle, a distensible bag and a face mask connected to the bag by a length of flexible tubing.  (13, part III, page 25) The notable criticism listed above was also aimed at these products, of which, when used to provide positive pressure breaths, probably forced in too much air too fast.  Because they were hand operated, they probably resulted in worker fatigue more rapidly than the pulmotor.

  1. Bahns, Ernest, "It began with the Pulmotor:  100 years of Artificial Ventilation," 2007, Germany, Drager Medical AG and CO. KG
  2. "Medical Discoveries,",, accessed, 7/29/13
  3. "Draeger Pulmotor," The Wood Library Museum,, accessed February 26, 2012
  4. "Medical Discoveries,",, accessed, 7/29/13
  5. "Iron Lung: 1929 Dinker Respirator," University of Virginia Historical Collections at the Claude Moore Health Sciences Library,", accessed February 26, 2012
  6. "Items of interest from various localities," Pipeline and gas journal, Jan. 13, 1913, page 34  
  7. "Pulmotor advertises gas company," Gas Age, volume 29, 1922, New York, Robbins Publishing Company Inc. 
  8. Cannon, Walter Bradford, George Washington Crile, Joseph Erlanger, Yandell Henderson, "Report of the Committee on Resuscitation from Mine Gases," Technical paper number 77, Department of Interior, Bureau of Mines, Joseph A. Holmes, Director, 1914, Washington, Government Printing Office
  9. Worthington, George, editor "Commercial Practice: Management, Rates, New Business," Electric Review, Volume 63, July 5 to December 7,1913, Chicago, Electric Review Publishing Company
  10. Parsons, Floyd W, editor, "The Pulmotor," Advertisement, Coal Age, Volume 11, number 2, January 13, 1917, New York, Hill Publishing Company, page 156
  11. Pulmotor advertisement appeared in The American City, Volume 12, January to June, 1915, New York, The Civic Press.  Similar ads by Draeger appeared in various other similar magazines.  
  12. Drinker, Phillip, Charles F. McKhann, "The use of a new apparatus for the prolonged administration of artificial respiration," 1986, Journal of the American Medical Association, issue 255, number 11, pages 1473-1475
  13. "Report: Great Britain Department of Scientific and Industrial Advisory Council: Second Report of the Mine Rescue Apparatus Research Committee," 1920 (reprinted 1921), London, His Majesty's Stationary Office, part II, Miscellaneous, page 25
  14. Gray, F. W., "The mining operations of the Dominion Coal Company," The Canadian Mining Journal, November 15, 1908, Volume XXIX, Number 22, Toronto; Published in the "Index: Canadian Mining Journal, volume 29, January 1, 1908, to December 31, 1908, The Mines Publishing Company Limited, Toronto, Ontario. Click the links for a better view of pictures. 
  15. Meltzer, S. J., "History and analysis of the methods of resuscitation," Medical Record: A Weekly Journal of Medicine and Surgery, July 7, 1917, Volume 92, Number 1, New York; Meltser
  16. Meltzer, S. J., "History and analysis of the methods of resuscitation," Medical Record: A Weekly Journal of Medicine and Surgery, July 7, 1917, Volume 92, Number 1, New York; Meltser references the following: Yandell Henderson: Technical Paper 77, Bureau of Mines, Washington, D.C., Government Printing Office, 1914, page 12