Friday, February 15, 2013

1920-1980: The evolution of oxygen delivery devices x

By the mid 1920s many of the challenges of oxygen therapy had been tackled.  Oxygen could be easily produced, stored in tanks, and delivered to the patient.  There also existed the means of confirming oxygenation status of patients, and the effects of oxygen therapy.  So the stage was set for oxygen to be introduced to hospitals.

In 1922 John Haldane wrote about his research in "The Therapeutic Administration of Oxygen."
Soon thereafter oxygen tanks became more and more common at the patient bedside.  The tanks were stored in closets, and when needed were strapped by the patient bedside. 

There were various devices available for providing oxygen, which included a metal nasal cannula, a nasal catheter, the oxygen chamber, the Haldane Apparatus, and the oxygen rebreather mask or mouthpiece and an oxygen tent.  .  For patients that were comatose, any device needed to provide therapeutic oxygenation could be used.  For awake and alert patients, the mask posed a claustrophobic feeling, and it was also hot.  The same was true with the oxygen tent.  So the physician would basically have to base what oxygen device he used on the patient.

According to one of my readers over at Respiratorycave.blogspot.com "The first practical oxygen tent was invented by Doctor Benjamin Eliasoph in 1921, at The Mount Sinai Hospital,New York, with rubberized fabric from the Goodyear Rubber Company, Aeronautical Division used for balloons such as the widely known Goodyear Blimp.  This information is confirmed in a New York Times obituary for Dr. Benjamin Eliasoph, which notes: "Dr. Benjamin Eliasoph, a physician at Mount Sinai Hospital who was a pioneer in the design of the oxygen tent, died Sunday at the hospital. He was 70 years old."

The first mass producible oxygen tent was invented by Doctor Leonard Hill.  It consisted of a canopy with slots so the patient could see out that was placed over the bed and patient, and a machine was set at the bedside that blew oxygen into the tent and over the patient.  Glover explains that there was no means of cooling the atmosphere inside these tents, and being inside was almost unbearably hot and uncomfortable for many patients.

Dennis Glover, in his 2010 book "History of Respiratory Therapy: Discovery and Evolution," said that the most common use for the oxygen tent was for patients presenting with cyanosis due to heart failure or pneumonia.  Some patients would beg to get out of the tents, Glover explains, yet once out they would became short of breath and they'd beg to get back in.  So it was sort of a double edged sword for the patient until the patient got better, if they got better.  Some critics complained such tents basically provided a tortuous method of ending a person's life, and petitioned for their demise.

Yet these tents were ultimately refined in 1926 by Alvin Barach so that the air would blow over ice, and this would cool the air inside the tent.  They were refined again in 1931 by John Emerson. 

In 1926 Alvin Barach invented an oxygen tent that blew air over ice chips to cool the temperature inside the tent.  This made it so being inside the tents were much more bareable.   Usually these tents were reserved to patients with pneumonia and heart failure. (2) In 1931 John Emerson invented an oxygen tent that had a cooling system.  Previous devices were prone to rust and failure.  (7)

The metal cannula was another device that was used.  It was a narrow metal pipe that was secured to the forehead by a strap that wrapped around the head, and at the lower end of the pipe were two prongs that were inserted into the nares.  I can imagine this may have felt awkward for the patient, but it may have been much nicer than having to lie inside an oxygen tent or having a rubber mask on your face.

The nasal catheter was introduced to the world by Lane in 1907, and introduced to the United States in 1931 by Waters and Wineland. (3)  Between 1920 and 1960 it was the most widely used method of delivering oxygen to patients was the nasal catheter. (8)

Glover explains that by the 1960s vinyl was invented and this technology spread to the medical profession.  Masks, catheters, nasal cannulas and tubing was now made of this new material, and were much more comfortable for patients.  (2)  Another benefit was the material was see through, and this allowed the caregivers to see right away if the mask was filling with secretions, vomit or pulmonary edema. 

Vinyl nasal cannulas also became the preferred basic oxygenation device, and this slowly caused the demise of the nasal catheter, which is no longer manufactured.

The nonrebreather was also introduced during the 1920s.  The only basic difference from the rebreather was a one way valve which opened on exhalation and allowed the patient to exhale into the room.  The one way valve closed on inspiratoin and caused the patietn to breathe approximately 80 percent oxygen that was stored in the reservoir. 

This was a good device for oxygenating patients suffering from acute anoxia, although oxygen tanks weren't trustworthy, rubber masks stuck to faces, and physicians, nurses, nurses aides and orderlies got busy.  So if the tank all of a sudden was empty, the patient might suffocate.  So to extinguish this risk, one of the valves was removed and the masks ultimately became more of a partial rebreather, providing around 50-60 percent oxygen. 

By the 1950s physicians observed that some patients with chronic bronchitis and emphysema became lethargic when exposed to high levels of oxygen.  So this brought about the introduction of the venturi mask.  This new mask was based on the venturi principle, and the degree of the opening on the venturi determines the amount of air entrained.  This allowed the physicians to provide an accurate and specified amount of oxygen to the patient.

So for patients you don't want to give too much oxygen to, the venturi mask was recommended.  Generally, for patients with bronchitis and emphysema, you would either use a low flow device like a nasal catheter or cannula, or you'd use the venturi mask.  These masks were (are) also nice for when you have a patient with an irregular respiratory rate because regardles of the patients minute ventilation, the patietn will still receive the preset level of oxygen. 

By the 1980s plastic had been invented, and during this decade most respiratory therapy devices were slowly replaced by plastic.  Plastic nasal cannulas, masks, and nebulizers were introduced in the early 1980s and slowly phased into various hospitals through assimilation. 

The earliest oxygen humidifiers were either made of metal or glass.  Until plastic was invented, none of the equipment here was disposable, and needed to be washed, sterilized, dried, and restocked on the shelves before being set up on the patient. 

References:
  1. Hess, Dean,  Neil MacIntyre, Shelley Misha,"Respiratory Care:  Principles and Practice," page 281
  2. Glover, Dennis, "History of Respiratory therapy: discovery and evolution, ," 2010, Indiana, page 94
  3. Wyka, Kenneth A., Paul J. Mathews, John Rutkowski, editors, "Foundations of Respiratory Care," 2012, U.S., Delmar, page 9
  4. Hess, Dean,  Neil MacIntyre, Shelley Misha,"Respiratory Care:  Principles and Practice," page 281
  5. 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
  6. 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
  7. 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
Further Reading:
  1. Use of oxygen in pneumonia in an oxygen chamber, page 466

No comments:

Post a Comment