Wednesday, November 9, 2016

1860: Salter's Consequences of asthma

Back in the 1850s Dr. Henry Hyde Salter wrote that "Asthma never kills; at least I have never seen a case in which a paroxysm proved fatal."  Rather than death, the disease causes certain consequences, none the greater than suffering that results from not being able to breathe.

When asthma does kills it is usually not pure asthma that kills, but asthma complicated by organic damage, such as asthma complicated with bronchitis, heart failure or kidney failure.  He said:
If death did take place from asthma it would be by slow asphyxia—by the circulation of imperfectly decarbonized blood; and before this occurred I think the spasm would yield. When a case of asthma terminates fatally it does so by the production of certain organic changes in the heart and lungs; and it is on this tendency to the generation of organic disease that the gravity of asthma depends.
So while asthma rarely kills, it does result in some consequences that affect the life of the asthmatic. He said:
If we examine the chest of an asthmatic who has but recently been affected with his disease, or whose attacks have been infrequent, we shall very likely find evidence of perfect anatomical soundness of all its organs: but if we examine him again in ten years we shall to a certainty, if the patient has in the interval suffered constantly from attacks of his malady, find evidence of organic disease of the lungs, and very likely of the heart.
The reason for this is because the organs are united with such "perfect anatomical soundness" that a "functional disorder cannot exist without dragging in it's train organic change."

In other words, when asthma attacks are frequent, a sequence of events occur within the body that impact the asthmatic's life, and make him a recognizable asthmatic, as opposed to a pure asthmatic with no anatomical changes.

So, what are the complications of asthma and why do they occur?  First we'll tack the consequences of asthma.  These consequences of asthma can be divided into four parts:

1.   Bronchiolar changes:  The direct results on the bronchial tubes themselves of the inordinate action of their walls. When the muslces that wrap around the air passages (also called "circular fibres of the branchiae," or "bronchial muscles) are overworked, they become hypertrophied (just like any other muscle of the body). This results in "permanent thickening of their walls and consequent narrowing of their calibre."  Such hypertrophied muscles more easily takes on a state of contraction resulting in "dyspneoea."  In other words, the more frequently the asthma occurs, the more likely exposure to exciting causes are to trigger an attack.  This may also result in some permanent contraction and permanent dyspnea, or what Salter refers to as "long-continued asthma."

2.   Heart changes: All those results of obstructed circulation, first pulmonary, then systemic, which the inadequate supply of air to the lungs induces.  The lungs become so shut down that it's nearly impossible for the heart to pump blood through them.  This results in:
  • Pulmonary arterial congestion (congested heart failure)
  • Distended right heart (hypertrophy)
  • Large, bulging veins trying to carry blood to the lungs, but unable (edema)
  • Scanty supply of oxygenated blood getting to left side of the heart (hypoxemia)
Basically, if all the bronchioles were to contract at the same time death would result.  However, in asthma only some of the bronchioles contract, and this simply results in severe discomfort, and the person (usually) does not die.  Oxygenated blood is diminished, but never stops altogether.

When this occurs over a long period of time, or often enough, it results in permanent organic changes to the heart and the lungs, which may result in continued (chronic) asthma and constant dyspnea.

Generally, organic changes to the lungs result in organic changes to the heart over time, if asthma attacks are not completely resolved (especially if there is a bronchitic component to the asthma).

3.   Emphysema:  That special result of the unequal and partial distribution of air to the lungs—emphysema. This is the most commonest morbid changes asthma produces.

Salter defined emphysema as "compensitory dilation, and the neighborhood of non-expandable lung."

Basically, it's air that is trapped in the lungs due to areas of the lungs that are blocked by bronchiolar contraction and mucus.  Escape of this air and mucus is prevented so long as the asthmatic paroxysm lasts.

"In the meantime," he said, "whatever may have been the length of the attack (and we know that it often lasted for days), the inspirator muscles are making the most violent efforts to fill the chest, and are, in fact, keeping it in a state of extreme distention."

Over time this organic change can result in permanently "non-expandable lung" units, resulting in an expanded emphysemitic chest.

From a photograph of an asthmatic, whose disease
dated from whooping-cough at three months old.
Photograph here is from Salter's Asthma Book.
4.   Asthmatic Physique:  The general effect of the disease on the physiognomy (facial features or expression) and build of the patient—the production of what may be called the asthmatic physique (see figure).
  • Exceedingly thin (often emaciated)
  • High shoulders
  • Back rounded
  • Walks in a stooped gate
  • Head burried between elevated shoulders
  • Chest is fixed and rigid, like a box
  • Enlargement of the thoracic cavity, like barrel chest of emphysema
  • While breathing, the reverse movement of the ribs can be seen, called pigeon-breast
  • Arms hang and do not swing
  • Limbs attenuated and bony
  • Every rib can be counted
  • Clothes hang loosely on them
  • Hands are cold, blue, thin and veiny (due to feebleness of circulation and dyspnea (either permanent or due to the present asthmatic attack)
  • Cyanotic hands, feet and face (not if the attack is short, and the length of time between attacks is long, such as what may occur in asthmatic children)
  • Anxious expression on face
  • Face is dusky or pale, and thin
  • Cheeks are hollow
  • Lines on face deeply marked
  • Mouth open
  • Jaw hanging
  • Eyes are turgid, watery and prominent (if you see this, you should check for enlarged heart)
  • Voice is feeble and slightly harsh and rough
  • He speaks as though he's trying to get all his words out in one sentence, as though he were making his last breath. 
  • His sentences and short and frequently interrupted by a dry cough
Most of these are generally present in other diseases that produce chronic dyspnea, and in the healthy asthmatic many may not be present.  Of this, Salter said:
In the purest cases of spasmodic asthma, in which there is no trace of dyspnoea in the intervals, they are the least marked, and are the most conspicuous in those which are complicated with some chronic bronchitis or bronchial congestion, so that I look upon their absence as a good sign, as a sign that the lungs are sound and unscathed; and it is because asthma seldom exists long without producing such changes as permanently embarrass the breathing, that these changes in the physiognomy and configuration come to be signs of asthma; they are just as much a part of its clinical history as those internal changes in the lungs and heart, of which they are the sure sign and accompaniment. I have, however, seen the asthmatic physique very strongly marked in some cases where the lungs were organically sound; but these were always cases where the paroxysms were very long, lasting for days or weeks, so that the efficient cause was in continued operation for a long time; or else they were cases in which the asthma had been very severe in childhood, when the figure was forming, so that it got set in the asthmatic shape, and, although the disease afterward quite disappeared, the figure never recovered itself. Such cases carry a certain highness of shoulders and roundness of back with them to the end of their days, however completely the asthma may be in mature life recovered from. Sometimes, however, on the disappearance of the disease, a wonderful improvement may take place in the figure, especially if the patient is young. (1, page 91)
So this is what we know of Salter's perspective of the consequences of asthma.  In a day when there were few remedies to prevent and treat the disease, such must have been a common picture of your average asthmatic.

Many of the characteristics above may go away as the asthma improves and doesn't reappear for a long time.  However, Salter said:

"I am of opinion that the occurance of asthma once renders the subject of it more liable ever afterword to a recurrance of it. It is very rare to hear of a person having a single attack; so rare that I am not sure that I have ever heard of a case." (1, page 95-6)
So while asthma may not occur until one is older, once it occurs the person will have a predisposition to it, and will probably have an attack at least once a month.  And it is for this reason that a majority of asthmatics will have a tendency to develop the consequences of asthma.

References:
  • Salter, Henry Hyde, "On Asthma: It's Pathology and Treatment," 1882, New York, William Wood and Company, (chapter V) pages 62-69, (chapter VI) 70-81.  (original publication of chapters in magazines during the 1850s. The articles were compiled and published as a book, the first edition of which was in 1860in London), Pages 82-96
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