Tuesday, June 24, 2014

Early respiratory therapy research

The 19th century gave birth to science based medicine, and this greatly effected respiratory therapy.  The following are some of the early debates the resulted in experiments, the results of which effect some of the methods still used to this day.  

1.  Pressure Therapy:  The Minnesota State Medical Society, in 1886, noted that it was known by the mid 19th century that exhaling against resistance will help dilate the air cells and rectify lung collapse. (4, page 45)  Tissier explains that theories existed by the turn of the 18th century that pressure therapy may be used therapeutically, and this resulted in the first devices to test this early in the 19th century. (1) Samuel Fitch may have been the first to utilize this information in creating what may have been the first type of pressure therapy in his Ramadge Inhaling Pipe in 1810. (5)  It provided resistance (pressure) against both inspiration and expiration.  You can read about the Ramadge Inhaling Pipe in this post

2.  Aerosolized Deposition into Lungs:  In 1856 Sales-Giron introduced the first nebulizer "and contended that the spray penetrated deeply into the respiratory tract, retaining all the elements of the mineral water."  The various experiments performed proved that Sales-Giron was accurate by his claims, and his product was accepted by the medical community.  Many various nebulizers were invented and trialed by patients during the 19th century, although no truly effective nebulizer hit the market until the electric nebulizer was invented in the 1930s.  (1, page 184-186)

3.  Simple mask versus tracheotomy:  About 1900 the debate was raging as to what was the best type of airway to use during surgery or life saving situations:  simple mask, intubation or tracheotomy.  It was determined that a mask keeps the passage to the stomach open, which could pose some problems.  One physician recommended a tracheotomy was unnecessary, and intubation through the nose was the best approach, plus it could be done by anyone.  Other physicians recommended tracheotomy for prolonged operations. One physician recommended tracheotomy to patients poisoned because it allows access to the mouth for medications.  (1, page 285)

4.  Large versus small aerosolized particles:  During the 1930s glass bulb nebulizers were operated by a rubber bulb syringe.  These nebulizers produced a mist for inhalation, although it was proved that most of the particles were large and impacted mainly in the upper respiratory tract.  This was good for perfume sprays, or even sprays meant to penetrate the throat, but not for sprays meant to reach the air passages.  Experiments performed by Huckel and published in 1925 demonstrated that aerosol particles had to be 5 microns or less, and be dense enough, to make it to the bronchi and alveoli to be effective. (3, page 10-11)  This lead to the invention of a baffle in the late 1930s to filter out large particles.  (2)  Studies were subsequently done that proved the smaller aerosol particles penetrated the air passages.  The baffle was added to a few glass nebulizers with bulb syringes in the late 1930s, although the Collision Nebulizer created a distinction between the atomizer and nebulizer.  The Atomizer created large aerolized particles to penetrate any surface (perfume sprays, paint sprays, antiseptic sprays) and the nebulizer produced a fine mist capable of penetrating the respiratory passages in the lungs.

References:
  1. Tissler, Paul Louis Alexandre, "Pneumotherapy: Including Aerotherapy and inhalation...," 1903, Philadelphia, Blakiston's sons and Company
  2. Rau, Joseph L, "Conference Proceedings:  Design Principles of Liquid Nebulization Devices Currently In Use," November 2002, Volume 47, Number 11, Page 1257
  3. Collision, W.E., "Inhalation therapy technique," 1935, London, William Heinemann
  4. Minnesota State Medical Society, "Transaction of the Minnesota State Medical Society," 1886, St. Paul, H. M. Smyth Printing Co.
  5. Fitch, Samuel Sheldon, "Six lectures on the uses of the lungs," 1847, New York, H. Carlisle, pages 91-93, 

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