Thursday, April 24, 2014

1717: Floyer establishes spasmotic theory of asthma

In 1698 Sir John Floyer, an asthmatic himself, published his book A Treatise of the Asthma.  In this book he became the first asthma expert to make the case for asthma as a separate disease from other lung disorders. This is significant because prior to this division all that was short of breath was asthma.

He also lived during a time when supernatural remedies were slowly going out of favor, yet some physicians, such as Floyer, didn't like the change.  Floyer preferred to treat asthma as a disease caused by an imbalance of the four humours (black bile, yellow bile, blood and phlegm) as opposed to some physiologic condition of the body.

Despite this, Floyer was wise enough to see that there was more to asthma than his predecessors assumed, and therefore Floyer became a significant figure in the evolution of the asthma definition.  Now surely he slowed progress some by rejecting fellow asthma experts with more scientifically linked ideas (such as Jean Baptiste van Helmont and Thomas Wilson), yet in other ways he did well.

However, to his credit, while he treated asthma by older methods, he was a supporter of the notion of asthma as a disease of contraction of the air passages.  Yet he also believed the diaphragm was a cause of the ailment, "which seemed to him rigid, and spasmotically drawn up by some contractile force within the thorax; and this force he considered to be the air tubes and lungs, contracted by an inflation of the membrane lining the chest and covering the lungs," according to John Charles Thorowgood in his 1894 book about asthma and chronic bronchitis. (2. page 10)

Thorowgood provides some intriguing quotes fromk the second edition of Floyers book A Treaties on Asthma that was published in 1717.  Thorowgood quotes Floyer as writing:
"I have assigned the immediate cause of the asthma to the straitness, compression, or constriction of the bronchia; and in the continued asthma (it's always there, or it's chronic) the causes must be constant, as dropsy, tuberculum, etc. The return of periodic asthma (it comes on only occasionally) depends on the defluxion (discharge, such as from a runny nose due to catahrr or inflammation) of humours on the primae viae (the bowels). Thus, the old notion of the asthma being a defluxion of serous humours is certainly true, because evident to our senses in the evacuation of serosities....  Some,' continues Floyer (p. 43), 'express their feeling, during a fit of asthma, as if the lungs rose, and were drawn upwards to choke them. Contraction of the vesicuise is very probable, because the bronchia are contracted, and the vesiculse have the same muscular fibres to help expiration, by which they may be drawn so up as not to admit the air.' (2, page 11)
Thorowgood also provides a passage from Floyer's book comparing the chest with bellows:
 'We can,' says he, 'move the bellows easily; but suppose a bladder tied within the bellows over the nozzle, so as to receive the air and suffer none to get into the cavity of the bellows, it will follow that in a perfect stoppage of all the entrances of air the bellows could not be opened; and if no more entered than may be contained in the bladder, the bellows would be opened but a little way, and would inspire difficultly. So it appears in the business of the asthma, the inspiration is difficult and laborious, because but little air can be admitted into the contracted bronchia, and the vesicular drawn up. This puts the scapular and intercostal muscles and diaphragm upon a violent endeavour to press in the air and open the lungs, which nisus (physicians trying to understand asthma) authors have mistaken, and supposed the pneumonic (lung) muscles, especially the diaphragm, to be convulsively affected; but it may easily be apprehended that the diaphragm cannot press the viscera (internal organs) downwards to enlarge the breast if the air cannot be admitted into the lungs to follow its depression and fill the cavity of the breast; and this is the true reason why the diaphragm cannot move in the asthmatic fit. The contraction and stiffness of the lungs during asthma causes a catalepsis (stiffness) or rigidity of the diaphragm—the part most unjustly accused of this tyrannic oppression.' (1, page 11-12)
Thorowgood notes that other physicians before Floyer noted the rigidity of the diaphragm and credit it as the "essential cause of asthma."  Floyer, on the other hand, while he notes this rigidity, contributes it to contraction of the air passages of the lungs.  The wheezing heard on expiration, therefore, is caused by the narrowed air passages, which is caused by contraction of the muscular fibres that wrap around them. (1, page 12)

Two other things of interest that Thorowgood mentions about Floyer:

1.  Floyer also refers to asthma that is associated with no other observable signs as hysterical asthma, and he refers to the "hysteric" who wheezes but produces no phlegm is proof that asthma is not caused by phlegm but by contraction of the air passages.  (1, page 12)

2.  Floyer clearly rejects the nervous theory of asthma postulated by Willis and van Helmont.  Thorowgood writes: "(floyer) regarded the contraction as brought about by mechanical pressure rather than by nervous influence seems clear, from his saying that certain writers of his day, Van Helmont and Dr. Willis, were wrong in regarding asthma as a convulsion, to be treated by anti-spasmodics, hot tinctures, gums, volatile salts, and sulphur medicines. The proper method is by evacuants, and remedies calculated to promote secretion and effect the discharge of humours —anti-congestive rather than anti-spasmodic treatment.

It is clear, though, by the writings of Floyer that he was probably the physician who established the spasmotic theory of asthma, which is also called the convulsive theory of asthma, or the bronchospasm theory of asthma.  He believed asthma was caused by contraction of the bronchi as opposed by a nervous disorder.   

References:
  1. Thorowgood, John C., "Asthma and Chronic Bronchitis: A New Edition of Notes on Asthma and Bronchial Asthma," 1894, London, Bailliere, Tyndall, & Cox.  The quotes from Floyer were referenced by Thorowgood from Floyers book "A Treaties on Asthma," which was published in 1717.  Pages referred to are in the quotes above. 

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