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
References:  
  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.

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