Monday, February 22, 2016

1819: Laennec uses stethoscope to redefine asthma

After he invented his stethoscope in 1816, Rene Laennec set out to use his newly developed tool to compare breath sounds with what he later found on autopsy. What he learned was that many diseases were incorrectly diagnosed as asthma. He therefore used his stethoscope to redefine the term asthma.

He listed a variety of diseases he suspected as having similar symptoms as asthma, and that other physicians often diagnosed as asthma, or a variety of it.  Some of these include: (1, page 435, 438-439)
  • Heart disease (diagnosed as cardiac asthma)
  • Diseases of the large vessels of the heart (diagnosed as cardiac asthma)
  • Dry catarrh (congestion of blood in the vessels of the lungs, inflammation)
  • Pituitous catarrh (inflammation with mucus, humid asthma)
  • Mucous catarrh (inflammation with increased mucus, humid asthma)
  • Chronic catarrh, either dry, pituitous or mucous (diagnosed as humid asthma)
  • Emphysema of the lungs 
  • Edema of the lungs (sometimes diagnosed as asthma)
  • Effusions of the pleural cavity (sometimes diagnosed as asthma)
  • Breathlessness caused by epilepsy (seizures)
  • Breathlessness caused by apoplexy (stroke)
  • Breathlessness caused by hysteria (psychological, nervous disorder)
  • Breathlessness caused by syncope (passing out) 
  • Hypertrophy or dilation of the heart  (1, page 435, 438-439) 
  • Congestion of blood in the lungs (1, page 442)
None of these, he said, should be diagnosed as asthma, and most of these should be diagnosed correctly by a trained pathologist.  (1, page 435)

He therefore refined the definition of asthma as such:

Nervous Asthma: Dypsnea with no signs of vascular congestion nor organic lesions of the lungs.  It is therefore caused by the nervous pathways, and is rarely fatal.  (1, page 435-436, 443)

There are two forms of nervous asthma:

1.  Asthma with puerile respiration: "The patient constantly feels the want of still more extensive respiration than he enjoys."  In other words, the patient can't catch his breath. The patient can't catch his breath due to "dilation of the pulmonary cells to their full capacity, and over the whole extent of the chest."  This occurs so that the patients "have not capacity enough to satisfy the wants of the system." (1, page 436-437)

The sound of the breathing is quite puerile. It is caused by a nervous response that causes an obstruction in the air passages by a "temporary obstruction of the bronchi by by a little mucus (that) impedes the transmission of the air to even a small portion of the lungs, the patient experiences an extreme oppression." (1, page 437)

This type of asthma is not very common, and usually short lived, because the patient usually easily expectorates the "little mucus" causing the problem.   (1, page 437)

It's common in patients with chronic mucus catarrh, although it can also be present in patients with nervous affections such as hysteria, or in those with poor tolerence to exercise, such as in obese folks.  (1, page 438)

2. Spasmotic Asthma:  Circular fibers, first discovered by Reisseissen, wrap around the air passages wrap around the bronchi (air passages) of the lungs. Spasmotic contraction of these of these fibres may obstruct the air passages "to such a degree as to prevent the transmission of air to a greater portion of the lung." (1, page 440)

He notes to having verified observation of these fibres, and says that it's impossible to deny that they might spasm, considering all muscles are prone to spasm.  (1, page 440)

Things that might trigger asthma are things that might "disturb the nervous influence:"
  • Odors (such as stored apples, tuberose, and heliotrope)
  • Changes of atmospheric electricity
  • Enclosed apartment
  • A vast plain
  • Want of light and free circulation of air
  • Emotions
The following are the treatment for asthma:
  • To treat catarrh: (1, page 449)
    • Emetics
    • Soap
    • Alkaline salts
    • Kermes
    • Squills
    • Ipecacauanha (1, page 449)
  • To treat nervousness: All of the following should be trialed "one after another" until the medicine that works best is found. The best general rule for their administration is, to begin with a small dose, to increase this gradually, and to employ the plants in substance, well preserved and recently powdered.  If we employ extracts, they must have been recently prepared and preserved with great care."  The medicines are:
    • Narcotics (decreases respiration, dyspnea, and spasms in lungs) (1, pages 449-450)
      • Opium
      • Belladonna
      • Stramonium
      • Phelladrium
      • Aquaticum
      • Aconitum
      • Napellus
      • Colchicum
      • Tobacco (smoked or taken internally)
      • Cicuta
      • Dulcamara
      • Hyoscyamus (1, page 450
    • Vegetable substances "that act powerfully on the nervous system."
      • Laurocerasus
      • Nux vomica
      • Boletus
      • Suaveolens
      • Meadow Saffron
    • Substances equally irritating to stomach and nervous system. They work to ease respiration, but not as well as narcotics. (1, page 450)
      • Tincture of cantharides
      • The arsenical solution 
      • Arsenic in vapor
      • The sulphate of zink
      • The muriate of barytes
      • Distilled water of cherry laurel (Laennec trialed)
      • Diluted prussic acit (Laennec trialed
      • Nitric aether
      • Sulphric aether (1, page 450)
      • Acetic aether (1, page 450-451)
    • Resins of fetid gums: No other class of medicine has a better effect on nervous dyspnea.  They "frequently relieve dyspnea, and moreover favor expectoration when there exists any catahrral complication. Even the mere smell of these substances in general, frequently produces a temporary alleviation; sometimes, however, it is injurious " (1, page 451)
      • Musk (give speedy relief)
      • Castor (give speedy relief)
      • Gum ammoniac
      • Assafaetida
      • Camphor (singly or dissolved in the oil of petroleum)
      • Myrrh (1, page 451)
    • Cinchona: Good for asthma paroxysms of a "strongly marked periodical character... (It) diminishes their severity, and sometimes stops them altogether."
    • Iron:  Dr. Bree say it "may dissipate an asthmatic paroxysm when present, but to prevent its return."  Dr. Laennec says that "subcarbonate of iron, given in graduated doses, from a scruple to a dram, was beneficial in retarding the accessions and in lessening their violence, in persons of a pallid and lymphatic constitution, and in habits relaxed by a long course of indolent enjoyment."  Works for asthma associated with dry catarrh and asthma that is purely nervous. (1, page 451)
    • Coffee: Also noted by Bree to stop and prevent an attack.  Several other physicians have also noted the usefulness of coffee.
    • Eat little (1, page 450
    • Sleep much (1, page 450
    • Breathing oxygen (1, page 450)
    • Electricity:  Recently done in the form of galvanism, has sometimes lessened dyspnea, although sometimes made it worse (1, page 451)
    • Emetics:  They work as "evacuants (helps you move bowels, purge), derivitives, and expectorants (helps you spit up phlegm), but also by directly influencing the nervous system; as their employment is often followed by an intermediate alleviation of the paroxysm." 
    • Blood letting (venesection): Must never omit it as an option "wherever the lividity of the countenance, the strength of the patient's constitution, or the over-action of the heart, indicate pulmonary congestion (inflammation); but we must be careful not to abuse this practice, which in general produces only a temporary advantage. Venesection is rarely useful after the first days; and its too frequent repetition, by weakening the patient, induces a risk if not of life, at least of greatly prolonging the duration of the attack." (1, page 451)
Overall, by using his stethoscope, Laennec separated asthma from other diseases that cause dyspnea.  In the process, he redefined pure asthma as mainly a nervous disorder associated with spasms of the air passages.   

  1. Laennec, Rene Theophile Hyacinthe, "A treaties on the diseases of the chest, and on mediate auscultation," tranlated by John Forbes, 1838, New York, Philadelphia, Samuel S. and William Wood, Thomas Cowperthwaite and Company
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1 comment:

  1. My family has a history of asthma that is why we have asthma meds that we can use when the condition attacks.