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."

References:
  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

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