Wednesday, February 1, 2017

1873: Berkart says asthma is merely a symptom

Dr. J.B. Berkart was Asistant-Physician to the Victoria Park Hospital for Diseases of the Chest.  So he was well acquainted with asthma.  Unlike his predecessor, Dr. Henry Hyde Salter, Berkart opposed the nervous and spasmotic theories of asthma.

Berkart understood that, as Dr. C.B. Williams proved in 1840, that the muscles surrounding the air passages could contract or spasm.  However, he believed that Paul Bert, who published the results of his own studies on the contractility of the lungs in 1870, proved that the lungs do not contract during an asthma attack.

Of Bert, Berkart wrote:
"In many of his experiments he failed to demonstrate the contractility of the lungs, but at last he succeeded in doing so; and he found, as the reason of his failure, that he "insufflated the lungs too much", which circumstance impedes their contraction.  But if Paul Bert has thus proven the contractility of the bronchial muscles, he has at the same time conclusively shown the impossibility that asthma can be due to a spasmodic stricture of the bronchial tubes in those cases in which it forms an integral part of the disease, namely, in emphysema. For that same cause which hinders the success of the physiological experiments fully exists under those pathological conditions. (1, page 537)
Berkart believed that Henry Hyde's theory that asthma is nervous simply because asthma leaves behind no physical signs was poppycock. (2, page 49-50) Of this, Berkart said:
For the absence of physical signs is no safe indicator of the absence also of pathological conditions, and all the positive evidence derived from experimental physiology only goes to show that the "bronchial muscles may contract"; but as to "how" and as to "when" nothing is known. (1, page 537)
Berkart likewise explained:
I  am prepared to show that, were even the entire nervous system bent upon producing a spasmotic contraction of the bronchial muscles, it would fail in its attempts, because they are in cases of asthma in such a state of nutrition as to be utterly incapable of contracting at all." (1, page 537)
Instead, asthma being the result of a neurosis that causes spasms of the air passages, Berkart postulated that asthma was merely a symptom that accompanies other diseases: (1, page 537)(2, page 110)
  1. Emphysema
  2. Bronchitis
  3. Other pulmonary affections 
  4. Cardiac affections (1, page 537)(2, page 110
Furthermore, he said asthma is most often secondary to emphysema and bronchitis, and "the rare cases in which these are supposed to be absent could only constitute an exception to the rule.  The exception, however, does by no means invalidate the rule." (1, page 438)

The proof that the exception "does by no means invalidate the rule," was proved, according to Berkart, by the experiments of Walshe.  Of this, Berkart wrote: 
So well has this fact been recognised by all clinical observers, that they more or less explicitly mention "an acute relaxation" (Walshe*, Diseases of the Lungs, 1871, page 209) of the bronchial walls in cases of acute bronchitis.  Therefore, what holds good in the acute, still more forcibly applies to the chronic affection.  Here indeed, are the bronchial muscles so completely soaked with serum, that, were this the sole change they undergo, it alone would surfice to render contraction of the muscles a matter of impossibility.  But very often the first outbreak  of an asthmatic attack is preceded by pathological changes of greater moment than bronchitis -- namely, by catarrhal pneumonia, the anatomical basis of whooping-cough, measles, etc; and that disease inflicts such injuries upon the bronchial walls, that their contraction is irrevocably lost." (1, page 538)
He therefore argued that there was no point in debating what causes the attack, as such debates were frivolous.  He said:
Gentlemen, we shall never arrive at the true nature of bronchial asthma if we continue to confine our attention to an attack itself, to its immediate causes, and to its peculiar type of respiration. In asthma, as well as in any other disease, the history of the case and its sequele will have to be carefully considered ; and then we shall find that, indeed, asthma is no independent disease, no dynamic affection of a nerve, but that it really forms a link in a chain of diseases, which commence with affections of the bronchi and terminate with emphysema, whilst asthma itself represents the stage intermediate between these two. (1, page 538)
As Salter was ultimately proved correct in his assertion that asthma was indeed a disease of bronchospasm, he was eventually proved wrong that asthma was a neurosis.  To the contrary, Berkart was ultimately proved wrong in his assertion that asthma was not a disease of bronchospasm, and was eventually proved correct that asthma was not a neurosis.

Berkart believed that asthma starts as a chronic catarrh, often in childhood, and over time develops into emphysema.  Since emphysema is rarely found in children, it usually gradually develops unnoticed into adulthood.

He said that even as the lungs become increasingly diseased, breathing is generally easy. "But when an obstacle arises," he said, "which for its removal requires a greater force than that of ordinary respiration, then the inability to effect the removal shows the deficient nutrition of the organ. It is this stage of developing emphysema-this stage of deficient elasticity of the lungs-which constitutes the anatomical basis of bronchial asthma." (1, page 538)

He thus explains asthma this way:
In typical bronchial asthma, the lungs are greatly distended, the thorax is in a position of extreme inspiration, and all the respiratory muscles are firmly contracted. Inspiration is short and abrupt, and the effort of the respiratory muscles, although prolonged and greatly increased, remains ineffectual. If an obstacle arise to the entrance and exit of air from the lungs, say the impaction of a tough pellet of mucus in a bronchus, a supplementary force is necessary in order to displace the obstacle and to effectually carry on the respiratory function. Such additional aid to expiration is obtained by deep inspiration; and this is easily effected, because it proceeds from the action of the inspiratory muscles, to which the lungs deficient in elasticity cannot offer any great resistance. Hence the easy and rapid overdistension of the lungs. (1, page 538)
As far as what triggers an asthma attack, Berkart noted both internal and extarnal "exciting causes," all of which "produce an obstacle to the interchange of gases, against which the deficient expiratory forces will for a long time labour in vain." (1, page 538-539)

These exciting causes were: (1, page 538-539)
  1. Tough and fibrinous sputa: The thicker it is, the harder the lungs have to work to expectorate it
  2. Inhalation of foreign bodies: Epecacuanha, pollen, etc. 
  3. Heat from ambient air:  It causes sputum to become crusty, forcing lungs to work extra hard
  4. Excitement, laughter: Sputum is displaced from one part of lung into another, diminishing the surface of respiration
  5. Edema (fluid) in lungs:  Occurs when kidney's become diseased
  6. Thrombosis and embolism (blood clot): Causes asthma symptoms (1, page 538-539)
In conclusion, Berkart wrote:
I may, therefore, in conclusion, state that asthma is a symptom which accompanies diseases of the lungs in which deficient elasticity is the prominent feature, and in consequences in which the existing expiratory forces are only able to overcome an obstacle to respiration after prolonged and increased efforts." (1, page 539)
Berkart, therefore, believed that asthma was not a disease entity of it's own, but rather was a symptom of, in most cases, bronchitis and emphysema. Therefore, despite physicians not being able to find physical signs that asthma exists, these signs do exist.  Berkart said:
A patient may daily expectorate several spittoonfuls of mucus, and yet the most practised and most careful observer may fail to detect, by means of percussion and auscultation, the least trace of disease. The reason is that the mucus forms and stagnates in a bronchus or bronchi, situated at some distance from the surface of the chest, in which position the adventitious sounds are, as the bronchial respiration is normally, obscured by the intervening healthy tissue of the lungs  (2, page 51-52)
Salter originally published his ideas in various articles throughout the 1950s, and later in the 1969 book: "On Asthma: It's Pathology and Treatment."  Berkart also published his ideas in various articles, and in 1978 published the book: "On Asthma: Its Pathology and Treatment."  While both authors used the same title for their respective books, the theories postulated were opposites.

Both Salter and Berkart are important to our asthma history in that they were both responsible for garnishing attention to our disease.  However, while their opinions were well established regarding the cause of asthma, the debate was ongoing.

*Walter Hayle Walshe (1812-1892)

  1. Berkart, J.B., "On the Nature of the so-called bronchial asthma," British Medical Journal, November 8, 1873, 2 (671), pages 537-539
  2. Berkart, J.B., "On Asthma: It's pathology and treatment," 1878, London
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